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Shi X, Zhang R, Liu Z, Zhao G, Guo J, Mao X, Fan B. Alternative Splicing Reveals Acute Stress Response of Litopenaeus vannamei at High Alkalinity. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2024; 26:103-115. [PMID: 38206418 DOI: 10.1007/s10126-023-10281-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024]
Abstract
Alkalinity is regarded as one of the primary stressors for aquatic animals in saline-alkaline water. Alternative splicing (AS) can significantly increase the diversity of transcripts and play key roles in stress response; however, the studies on AS under alkalinity stress of crustaceans are still limited. In the present study, we devoted ourselves to the study of AS under acute alkalinity stress at control (50 mg/L) and treatment groups (350 mg/L) by RNA-seq in pacific white shrimp (Litopenaeus vannamei). We identified a total of 10,556 AS events from 4865 genes and 619 differential AS (DAS) events from 519 DAS genes in pacific white shrimp. Functional annotation showed that the DAS genes primarily involved in spliceosome. Five splicing factors (SFs), U2AF1, PUF60, CHERP, SR140 and SRSF2 were significantly up-regulated and promoted AS. Furthermore, alkalinity activated the Leukocyte transendothelial migration, mTOR signaling pathway and AMPK signaling pathway, which regulated MAPK1, EIF3B and IGFP-RP1 associated with these pathways. We also studied three SFs (HSFP1, SRSF2 and NHE-RF1), which underwent AS to form different transcript isoforms. The above results demonstrated that AS was a regulatory mechanism in pacific white shrimp in response to acute alkalinity stress. SFs played vital roles in AS of pacific white shrimp, such as HSFP1, SRSF2 and NHE-RF1. DAS genes were significantly modified in immunity of pacific white shrimp to cope with alkalinity stress. This is the first study on the response of AS to acute alkalinity stress, which provided scientific basis for AS mechanism of crustaceans response to alkalinity stress.
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Affiliation(s)
- Xiang Shi
- College of Animal Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Gansu Province, Lanzhou, 730070, China
| | - Ruiqi Zhang
- College of Animal Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Gansu Province, Lanzhou, 730070, China.
| | - Zhe Liu
- College of Animal Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Gansu Province, Lanzhou, 730070, China
| | - Guiyan Zhao
- College of Animal Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Gansu Province, Lanzhou, 730070, China
| | - Jintao Guo
- College of Animal Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Gansu Province, Lanzhou, 730070, China
| | - Xue Mao
- College of Animal Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Gansu Province, Lanzhou, 730070, China
| | - Baoyi Fan
- College of Animal Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Gansu Province, Lanzhou, 730070, China
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Itou T, Ishibashi Y, Oguri Y, Hashimura M, Yokoi A, Harada Y, Fukagawa N, Hayashi M, Ono M, Kusano C, Saegusa M. EBP50 Depletion and Nuclear β-Catenin Accumulation Engender Aggressive Behavior of Colorectal Carcinoma through Induction of Tumor Budding. Cancers (Basel) 2023; 16:183. [PMID: 38201610 PMCID: PMC10778391 DOI: 10.3390/cancers16010183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/19/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024] Open
Abstract
Ezin-radixin-moesin-binding phosphoprotein 50 (EBP50) is a scaffold protein that interacts with several partner molecules including β-catenin. Here, we examined the crosstalk between EBP50 and nuclear catenin during colorectal carcinoma (CRC) progression. In clinical samples, there were no correlations between the subcellular location of EBP50 and any clinicopathological factors. However, EBP50 expression was significantly lower specifically in the outer areas of tumor lesions, in regions where tumor budding (BD) was observed. Low EBP50 expression was also significantly associated with several unfavorable prognostic factors, suggesting that EBP50 depletion rather than its overexpression or subcellular distribution plays an important role in CRC progression. In CRC cell lines, knockout of EBP50 induced epithelial-mesenchymal transition (EMT)-like features, decreased proliferation, accelerated migration capability, and stabilized nuclear β-catenin due to disruption of the interaction between EBP50 and β-catenin at the plasma membrane. In addition, Slug expression was significantly higher in outer lesions, particularly in BD areas, and was positively correlated with nuclear β-catenin status, consistent with β-catenin-driven transactivation of the Slug promoter. Together, our data suggest that EBP50 depletion releases β-catenin from the plasma membrane in outer tumor lesions, allowing β-catenin to accumulate and translocate to the nucleus, where it transactivates the Slug gene to promote EMT. This in turn triggers tumor budding and contributes to the progression of CRC to a more aggressive phase.
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Affiliation(s)
- Takashi Itou
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
- Department of Gastroenterology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan;
| | - Yu Ishibashi
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
- Department of Gastroenterology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan;
| | - Yasuko Oguri
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
| | - Miki Hashimura
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
| | - Ako Yokoi
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
| | - Yohei Harada
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
- Department of Gastroenterology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan;
| | - Naomi Fukagawa
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
- Department of Gastroenterology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan;
| | - Misato Hayashi
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
| | - Mototsugu Ono
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
| | - Chika Kusano
- Department of Gastroenterology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan;
| | - Makoto Saegusa
- Department of Pathology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (T.I.); (Y.I.); (Y.O.); (M.H.); (A.Y.); (Y.H.); (N.F.); (M.H.); (M.O.)
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Lin C, Lin P, Lin H, Yao H, Liu S, He R, Chen H, Teng Z, Hoffman RM, Ye J, Zhu G. SLC26A3/NHERF2-IκB/NFκB/p65 feedback loop suppresses tumorigenesis and metastasis in colorectal cancer. Oncogenesis 2023; 12:41. [PMID: 37573425 PMCID: PMC10423209 DOI: 10.1038/s41389-023-00488-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 07/25/2023] [Accepted: 07/28/2023] [Indexed: 08/14/2023] Open
Abstract
Colorectal cancer (CRC) is a formidable disease due to the intricate mechanisms that drive its proliferation and metastasis. Despite significant progress in cancer research, the integration of these mechanisms that influence cancer cell behavior remains elusive. Therefore, it is imperative to comprehensively elucidate the underlying mechanisms driving CRC proliferation and metastasis. In this study, we reported a novel role of SLC26A3 in suppressing CRC progression. We found that SLC26A3 expression was downregulated in CRC, which was proportionally correlated with survival. Our in vivo and in vitro experiments demonstrated that up-regulation of SLC26A3 inhibited CRC proliferation and metastasis, while down-regulation of SLC26A3 promoted CRC progression by modulating the expression level of IκB. Furthermore, we identified NHERF2 as a novel interacting protein of SLC26A3 responsible for stabilizing the IκB protein and removing ubiquitination modification. Mechanistically, SLC26A3 augmented the interaction between NHERF2 and IκB, subsequently reducing its degradation. This process inhibited the dissociation of p65 from the IκB/p65/p50 complex and reduced the translocation of p65 from the cytoplasm to the nucleus. Moreover, our investigation revealed that NF-κB/p65 directly bound to the promoter of SLC26A3, leading to a decline in its mRNA expression. Thus, SLC26A3 impeded the nuclear translocation of NF-κB/p65, enhancing the transcription of SLC26A3 and establishing a positive regulatory feedback loop in CRC cells. Collectively, these results suggest that a SLC26A3/NHERF2-IκB/NF-κB/p65 signaling loop suppresses proliferation and metastasis in CRC cells. These findings propose a novel SLC26A3-driven signaling loop that regulates proliferation and metastasis in CRC, providing promising therapeutic interventions and prognostic targets for the management of CRC.
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Affiliation(s)
- Chunlin Lin
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, 350000, China
- National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Penghang Lin
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, 350000, China
| | - Huayan Lin
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China
- National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Hengxin Yao
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, 350000, China
| | - Songyi Liu
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, 350000, China
| | - Ruofan He
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, 350000, China
| | - Hui Chen
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, 350000, China
| | - Zuhong Teng
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, 350000, China
| | - Robert M Hoffman
- AntiCancer, Inc, San Diego, CA, USA
- Department of Surgery, University of California, San Diego, CA, USA
| | - Jianxin Ye
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China.
- National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, China.
| | - Guangwei Zhu
- Department of Gastrointestinal Surgery 2 Section, Institute of Abdominal Surgery, Key Laboratory of accurate diagnosis and treatment of cancer, The First Hospital Affiliated to Fujian Medical University, Fuzhou, 350005, China.
- National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, China.
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Donowitz M, Sarker R, Lin R, McNamara G, Tse CM, Singh V. Identification of Intestinal NaCl Absorptive-Anion Secretory Cells: Potential Functional Significance. Front Physiol 2022; 13:892112. [PMID: 35928564 PMCID: PMC9343792 DOI: 10.3389/fphys.2022.892112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Use of human enteroids studied in the undifferentiated and differentiated state that mimic the intestinal crypt and villus, respectively, has allowed studies of multiple enterocyte populations, including a large population of enterocytes that are transitioning from the crypt to the villus. This population expresses NHE3, DRA, and CFTR, representing a combination of Na absorptive and anion secretory functions. In this cell population, these three transporters physically interact, which affects their baseline and regulated activities. A study of this cell population and differentiated Caco-2 cells transduced with NHE3 and endogenously expressing DRA and CFTR has allowed an understanding of previous studies in which cAMP seemed to stimulate and inhibit DRA at the same time. Understanding the contributions of these cells to overall intestinal transport function as part of the fasting and post-prandial state and their contribution to the pathophysiology of diarrheal diseases and some conditions with constipation will allow new approaches to drug development.
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Affiliation(s)
- Mark Donowitz
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
- *Correspondence: Mark Donowitz,
| | - Rafiquel Sarker
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Ruxian Lin
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - George McNamara
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Chung Ming Tse
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Varsha Singh
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Nikolovska K, Seidler UE, Stock C. The Role of Plasma Membrane Sodium/Hydrogen Exchangers in Gastrointestinal Functions: Proliferation and Differentiation, Fluid/Electrolyte Transport and Barrier Integrity. Front Physiol 2022; 13:899286. [PMID: 35665228 PMCID: PMC9159811 DOI: 10.3389/fphys.2022.899286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/19/2022] [Indexed: 12/11/2022] Open
Abstract
The five plasma membrane Na+/H+ exchanger (NHE) isoforms in the gastrointestinal tract are characterized by distinct cellular localization, tissue distribution, inhibitor sensitivities, and physiological regulation. NHE1 (Slc9a1) is ubiquitously expressed along the gastrointestinal tract in the basolateral membrane of enterocytes, but so far, an exclusive role for NHE1 in enterocyte physiology has remained elusive. NHE2 (Slc9a2) and NHE8 (Slc9a8) are apically expressed isoforms with ubiquitous distribution along the colonic crypt axis. They are involved in pHi regulation of intestinal epithelial cells. Combined use of a knockout mouse model, intestinal organoid technology, and specific inhibitors revealed previously unrecognized actions of NHE2 and NHE8 in enterocyte proliferation and differentiation. NHE3 (Slc9a3), expressed in the apical membrane of differentiated intestinal epithelial cells, functions as the predominant nutrient-independent Na+ absorptive mechanism in the gut. The new selective NHE3 inhibitor (Tenapanor) allowed discovery of novel pathophysiological and drug-targetable NHE3 functions in cystic-fibrosis associated intestinal obstructions. NHE4, expressed in the basolateral membrane of parietal cells, is essential for parietal cell integrity and acid secretory function, through its role in cell volume regulation. This review focuses on the expression, regulation and activity of the five plasma membrane Na+/H+ exchangers in the gastrointestinal tract, emphasizing their role in maintaining intestinal homeostasis, or their impact on disease pathogenesis. We point to major open questions in identifying NHE interacting partners in central cellular pathways and processes and the necessity of determining their physiological role in a system where their endogenous expression/activity is maintained, such as organoids derived from different parts of the gastrointestinal tract.
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Ran L, Yan T, Zhang Y, Niu Z, Kan Z, Song Z. The recycling regulation of sodium-hydrogen exchanger isoform 3(NHE3) in epithelial cells. Cell Cycle 2021; 20:2565-2582. [PMID: 34822321 DOI: 10.1080/15384101.2021.2005274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
As the main exchanger of electroneutral NaCl absorption, sodium-hydrogen exchanger isoform 3 (NHE3) circulates in the epithelial brush border (BB) and intracellular compartments in a multi-protein complex. The size of the NHE3 complex changes during rapid regulation events. Recycling regulation of NHE3 in epithelial cells can be roughly divided into three stages. First, when stimulated by Ca2+, cGMP, and cAMP-dependent signaling pathways, NHE3 is converted from an immobile complex found at the apical microvilli (MV) into an easily internalized and mobile form that relocates to a compartment near the base of the MV. Second, NHE3 is internalized by clathrin and albumin-dependent pathways into cytoplasmic endosomal compartments, where the complex is reprocessed and reassembled. Finally, NHE3 is translocated from the recycling endosomes (REs) to the apex of epithelial cells, a process that can be stimulated by an increase in sodium-glucose cotransporter 1 (SGLT1) activity, epidermal growth factor receptor (EGFR) signaling, Ca2+ signaling, and binding to βPix and SH3 and multiple ankyrin repeat domains 2 (Shank2) proteins. This review describes the molecular steps and protein interactions involved in the recycling movement of NHE3 from the apex of epithelial cells, into vesicles, where it is reprocessed and reassembled, and returned to its original location on the plasma membrane, where it exerts its physiological function.
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Affiliation(s)
- Ling Ran
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Tao Yan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China
| | - Yiling Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zheng Niu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zifei Kan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zhenhui Song
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
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Das B, Okamoto K, Rabalais J, Young JA, Barrett KE, Sivagnanam M. Aberrant Epithelial Differentiation Contributes to Pathogenesis in a Murine Model of Congenital Tufting Enteropathy. Cell Mol Gastroenterol Hepatol 2021; 12:1353-1371. [PMID: 34198013 PMCID: PMC8479479 DOI: 10.1016/j.jcmgh.2021.06.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 06/18/2021] [Accepted: 06/21/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Congenital tufting enteropathy (CTE) is an intractable diarrheal disease of infancy caused by mutations of epithelial cell adhesion molecule (EpCAM). The cellular and molecular basis of CTE pathology has been elusive. We hypothesized that the loss of EpCAM in CTE results in altered lineage differentiation and defects in absorptive enterocytes thereby contributing to CTE pathogenesis. METHODS Intestine and colon from mice expressing a CTE-associated mutant form of EpCAM (mutant mice) were evaluated for specific markers by quantitative real-time polymerase chain reaction, Western blotting, and immunostaining. Body weight, blood glucose, and intestinal enzyme activity were also investigated. Enteroids derived from mutant mice were used to assess whether the decreased census of major secretory cells could be rescued. RESULTS Mutant mice exhibited alterations in brush-border ultrastructure, function, disaccharidase activity, and glucose absorption, potentially contributing to nutrient malabsorption and impaired weight gain. Altered cell differentiation in mutant mice led to decreased enteroendocrine cells and increased numbers of nonsecretory cells, though the hypertrophied absorptive enterocytes lacked key features, causing brush border malfunction. Further, treatment with the Notch signaling inhibitor, DAPT, increased the numbers of major secretory cell types in mutant enteroids (graphical abstract 1). CONCLUSIONS Alterations in intestinal epithelial cell differentiation in mutant mice favor an increase in absorptive cells at the expense of major secretory cells. Although the proportion of absorptive enterocytes is increased, they lack key functional properties. We conclude that these effects underlie pathogenic features of CTE such as malabsorption and diarrhea, and ultimately the failure to thrive seen in patients.
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Affiliation(s)
- Barun Das
- Department of Pediatrics, University of California, San Diego, La Jolla, California
| | - Kevin Okamoto
- Department of Pediatrics, University of California, San Diego, La Jolla, California
| | - John Rabalais
- Department of Pediatrics, University of California, San Diego, La Jolla, California
| | - Jocelyn A. Young
- Department of Pediatrics, University of California, San Diego, La Jolla, California,Department of Pediatrics, Rady Children’s Hospital, San Diego, California
| | - Kim E. Barrett
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Mamata Sivagnanam
- Department of Pediatrics, University of California, San Diego, La Jolla, California,Department of Pediatrics, Rady Children’s Hospital, San Diego, California,Correspondence Address correspondence to: Mamata Sivagnanam, MD, Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, 9500 Gilman Drive, La Jolla, CA 92093. fax: 858-967-8917.
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ACE2 interaction with cytoplasmic PDZ protein enhances SARS-CoV-2 invasion. iScience 2021; 24:102770. [PMID: 34189428 PMCID: PMC8223119 DOI: 10.1016/j.isci.2021.102770] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/23/2021] [Accepted: 06/21/2021] [Indexed: 12/26/2022] Open
Abstract
SARS-CoV-2 is responsible for the global COVID-19 pandemic. Angiotensin converting enzyme 2 (ACE2) is the membrane-delimited receptor for SARS-CoV-2. Lung, intestine, and kidney, major sites of viral infection, express ACE2 that harbors an intracellular, carboxy-terminal PDZ-recognition motif. These organs prominently express the PDZ protein Na+/H+ exchanger regulatory factor-1 (NHERF1). Here, we report NHERF1 tethers ACE2 and augments SARS-CoV-2 cell entry. ACE2 directly binds both NHERF1 PDZ domains. Disruption of either NHERF1 PDZ core-binding motif or the ACE2 PDZ recognition sequence eliminates interaction. Proximity ligation assays establish that ACE2 and NHERF1 interact at constitutive expression levels in human lung and intestine cells. Ablating ACE2 interaction with NHERF1 accelerated SARS-CoV-2 cell entry. Conversely, elimination of the ACE2 C-terminal PDZ-binding motif decreased ACE2 membrane residence and reduced pseudotyped virus entry. We conclude that the PDZ interaction of ACE2 with NHERF1 facilitates SARS-CoV-2 internalization. β-Arrestin is likely indispensable, as with G protein-coupled receptors. The SARS-CoV-2 receptor ACE2 C-terminal PDZ-recognition motif 802QTSF805 binds to NHERF1 NHERF1 and ACE2 interact directly in SARS-CoV-2-susceptible lung and intestine cells NHERF1 expression correlates with SARS-CoV-2 entry by regulating ACE2 membrane abundance β-Arrestins may cooperate with NHERF1 to promote ACE2-mediated SARS-CoV-2 cell entry
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Vistrup-Parry M, Sneddon WB, Bach S, Strømgaard K, Friedman PA, Mamonova T. Multisite NHERF1 phosphorylation controls GRK6A regulation of hormone-sensitive phosphate transport. J Biol Chem 2021; 296:100473. [PMID: 33639163 PMCID: PMC8042174 DOI: 10.1016/j.jbc.2021.100473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 12/13/2022] Open
Abstract
The type II sodium-dependent phosphate cotransporter (NPT2A) mediates renal phosphate uptake. The NPT2A is regulated by parathyroid hormone (PTH) and fibroblast growth factor 23, which requires Na+/H+ exchange regulatory factor-1 (NHERF1), a multidomain PDZ-containing phosphoprotein. Phosphocycling controls the association between NHERF1 and the NPT2A. Here, we characterize the critical involvement of G protein–coupled receptor kinase 6A (GRK6A) in mediating PTH-sensitive phosphate transport by targeted phosphorylation coupled with NHERF1 conformational rearrangement, which in turn allows phosphorylation at a secondary site. GRK6A, through its carboxy-terminal PDZ recognition motif, binds NHERF1 PDZ1 with greater affinity than PDZ2. However, the association between NHERF1 PDZ2 and GRK6A is necessary for PTH action. Ser162, a PKCα phosphorylation site in PDZ2, regulates the binding affinity between PDZ2 and GRK6A. Substitution of Ser162 with alanine (S162A) blocks the PTH action but does not disrupt the interaction between NHERF1 and the NPT2A. Replacement of Ser162 with aspartic acid (S162D) abrogates the interaction between NHERF1 and the NPT2A and concurrently PTH action. We used amber codon suppression to generate a phosphorylated Ser162(pSer162)-PDZ2 variant. KD values determined by fluorescence anisotropy indicate that incorporation of pSer162 increased the binding affinity to the carboxy terminus of GRK6A 2-fold compared with WT PDZ2. Molecular dynamics simulations predict formation of an electrostatic network between pSer162 and Asp183 of PDZ2 and Arg at position −1 of the GRK6A PDZ-binding motif. Our results suggest that PDZ2 plays a regulatory role in PTH-sensitive NPT2A-mediated phosphate transport and phosphorylation of Ser162 in PDZ2 modulates the interaction with GRK6A.
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Affiliation(s)
- Maria Vistrup-Parry
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - W Bruce Sneddon
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Sofie Bach
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Peter A Friedman
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Tatyana Mamonova
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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Kumar A, Balbach J. Inactivation of parathyroid hormone: perspectives of drug discovery to combating hyperparathyroidism. Curr Mol Pharmacol 2021; 15:292-305. [PMID: 33573587 DOI: 10.2174/1874467214666210126112839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/09/2020] [Accepted: 11/10/2020] [Indexed: 11/22/2022]
Abstract
Hormonal coordination is tightly regulated within the human body and thus regulates human physiology. The parathyroid hormone (PTH), a member of the endocrine system, regulates the calcium and phosphate level within the human body. Under non-physiological conditions, PTH levels get upregulated (hyperparathyroidism) or downregulated (hypoparathyroidism) due to external or internal factors. In the case of hyperparathyroidism, elevated PTH stimulates cellular receptors present in the bones, kidneys, and intestines to increase the blood calcium level, leading to calcium deposition. This eventually causes various symptoms including kidney stones. Currently, there is no known medication that directly targets PTH in order to suppress its function. Therefore, it is of great interest to find novel small molecules or any other means that can modulate PTH function. The molecular signaling of PTH starts by binding of its N-terminus to the G-protein coupled PTH1/2 receptor. Therefore, any intervention that affects the N-terminus of PTH could be a lead candidate for treating hyperparathyroidism. As a proof-of-concept, there are various possibilities to inhibit molecular PTH function by (i) a small molecule, (ii) N-terminal PTH phosphorylation, (iii) fibril formation and (iv) residue-specific mutations. These modifications put PTH into an inactive state, which will be discussed in detail in this review article. We anticipate that exploring small molecules or other means that affect the N-terminus of PTH could be lead candidates in combating hyperparathyroidism.
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Affiliation(s)
- Amit Kumar
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College of Science, Technology and Medicine London, South Kensington, London SW7 2BU. United Kingdom
| | - Jochen Balbach
- Institute of Physics, Biophysics, Martin-Luther-University Halle- Wittenberg. Germany
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11
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Álvarez-Carrión L, Gutiérrez-Rojas I, Rodríguez-Ramos MR, Ardura JA, Alonso V. MINDIN Exerts Protumorigenic Actions on Primary Prostate Tumors via Downregulation of the Scaffold Protein NHERF-1. Cancers (Basel) 2021; 13:436. [PMID: 33498862 PMCID: PMC7865820 DOI: 10.3390/cancers13030436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 11/17/2022] Open
Abstract
Advanced prostate cancer preferential metastasis to bone is associated with osteomimicry. MINDIN is a secreted matrix protein upregulated in prostate tumors that overexpresses bone-related genes during prostate cancer progression. Na+/H+ exchanger regulatory factor (NHERF-1) is a scaffold protein that has been involved both in tumor regulation and osteogenesis. We hypothesize that NHERF-1 modulation is a mechanism used by MINDIN to promote prostate cancer progression. We analyzed the expression of NHERF-1 and MINDIN in human prostate samples and in a premetastatic prostate cancer mouse model, based on the implantation of prostate adenocarcinoma TRAMP-C1 (transgenic adenocarcinoma of the mouse prostate) cells in immunocompetent C57BL/6 mice. The relationship between NHERF-1 and MINDIN and their effects on cell proliferation, migration, survival and osteomimicry were evaluated. Upregulation of MINDIN and downregulation of NHERF-1 expression were observed both in human prostate cancer samples and in the TRAMP-C1 model. MINDIN silencing restored NHERF-1 expression to control levels in the mouse model. Stimulation with MINDIN reduced NHERF-1 expression and triggered its mobilization from the plasma membrane to the cytoplasm in TRAMP-C1 cells. MINDIN-dependent downregulation of NHERF-1 promoted tumor cell migration and proliferation without affecting osteomimicry and adhesion. We propose that MINDIN downregulates NHERF-1 expression leading to promotion of processes involved in prostate cancer progression.
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Affiliation(s)
- Luis Álvarez-Carrión
- Bone Physiopathology Laboratory, Applied Molecular Medicine Institute (IMMA), Universidad San Pablo-CEU, CEU Universities, Campus Monteprincipe, 28925 Alcorcón, Spain; (L.Á.-C.); (I.G.-R.); (M.R.R.-R.)
| | - Irene Gutiérrez-Rojas
- Bone Physiopathology Laboratory, Applied Molecular Medicine Institute (IMMA), Universidad San Pablo-CEU, CEU Universities, Campus Monteprincipe, 28925 Alcorcón, Spain; (L.Á.-C.); (I.G.-R.); (M.R.R.-R.)
| | - María Rosario Rodríguez-Ramos
- Bone Physiopathology Laboratory, Applied Molecular Medicine Institute (IMMA), Universidad San Pablo-CEU, CEU Universities, Campus Monteprincipe, 28925 Alcorcón, Spain; (L.Á.-C.); (I.G.-R.); (M.R.R.-R.)
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad San Pablo-CEU, CEU Universities, Campus Monteprincipe, 28925 Alcorcón, Spain
| | - Juan A. Ardura
- Bone Physiopathology Laboratory, Applied Molecular Medicine Institute (IMMA), Universidad San Pablo-CEU, CEU Universities, Campus Monteprincipe, 28925 Alcorcón, Spain; (L.Á.-C.); (I.G.-R.); (M.R.R.-R.)
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad San Pablo-CEU, CEU Universities, Campus Monteprincipe, 28925 Alcorcón, Spain
| | - Verónica Alonso
- Bone Physiopathology Laboratory, Applied Molecular Medicine Institute (IMMA), Universidad San Pablo-CEU, CEU Universities, Campus Monteprincipe, 28925 Alcorcón, Spain; (L.Á.-C.); (I.G.-R.); (M.R.R.-R.)
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad San Pablo-CEU, CEU Universities, Campus Monteprincipe, 28925 Alcorcón, Spain
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Mamonova T, Friedman PA. Noncanonical Sequences Involving NHERF1 Interaction with NPT2A Govern Hormone-Regulated Phosphate Transport: Binding Outside the Box. Int J Mol Sci 2021; 22:1087. [PMID: 33499384 PMCID: PMC7866199 DOI: 10.3390/ijms22031087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/27/2022] Open
Abstract
Na+/H+ exchange factor-1 (NHERF1), a multidomain PDZ scaffolding phosphoprotein, is required for the type II sodium-dependent phosphate cotransporter (NPT2A)-mediated renal phosphate absorption. Both PDZ1 and PDZ2 domains are involved in NPT2A-dependent phosphate uptake. Though harboring identical core-binding motifs, PDZ1 and PDZ2 play entirely different roles in hormone-regulated phosphate transport. PDZ1 is required for the interaction with the C-terminal PDZ-binding sequence of NPT2A (-TRL). Remarkably, phosphocycling at Ser290 distant from PDZ1, the penultimate step for both parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23) regulation, controls the association between NHERF1 and NPT2A. PDZ2 interacts with the C-terminal PDZ-recognition motif (-TRL) of G Protein-coupled Receptor Kinase 6A (GRK6A), and that promotes phosphorylation of Ser290. The compelling biological puzzle is how PDZ1 and PDZ2 with identical GYGF core-binding motifs specifically recognize distinct binding partners. Binding determinants distinct from the canonical PDZ-ligand interactions and located "outside the box" explain PDZ domain specificity. Phosphorylation of NHERF1 by diverse kinases and associated conformational changes in NHERF1 add more complexity to PDZ-binding diversity.
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Affiliation(s)
- Tatyana Mamonova
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA;
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13
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Bannert K, Berlin P, Reiner J, Lemcke H, David R, Engelmann R, Lamprecht G. SNX27 regulates DRA activity and mediates its direct recycling by PDZ-interaction in early endosomes at the apical pole of Caco2 cells. Am J Physiol Gastrointest Liver Physiol 2020; 318:G854-G869. [PMID: 32116023 DOI: 10.1152/ajpgi.00374.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
DRA (downregulated in adenoma, SLC26A3) and NHE3 (Na+/H+ exchanger 3, SLC9A3) together mediate intestinal electroneutral NaCl absorption. Both transporters contain PDZ (postsynaptic density 95, disc large, zonula occludens 1) binding motifs and interact with PDZ adaptor proteins regulating their activity and recycling. SNX27 (sorting nexin 27) contains a PDZ domain and is involved in the recycling of cargo proteins including NHE3. The interaction of SNX27 with DRA and its potential role for the activity and recycling of DRA have been evaluated in this study. SNX27 specifically interacts with DRA via its PDZ domain. The knockdown (KD) of SNX27 reduced DRA activity by 50% but was not accompanied by a decrease of DRA surface expression. This indicates that DRA is trafficked to specific functional domains in the plasma membrane in which DRA is particularly active. Consistently, the disruption of lipid raft integrity by methyl-β-cyclodextrin has an inhibitory effect on DRA activity that was strongly reduced after SNX27 KD. In differentiated intestinal Caco2 cells, superresolution microscopy and a novel quantitative axial approach revealed that DRA and SNX27 colocalize in rab5-positive early endosomes at the apical pole. SNX27 regulates the activity of DRA in the apical plasma membrane through binding with its PDZ domain. This interaction occurs in rab5-positive early endosomes at the apical pole of differentiated intestinal Caco2 cells. SNX27 is involved in the direct recycling of DRA to the plasma membrane where it is inserted into lipid rafts facilitating increased activity.NEW & NOTEWORTHY SNX27 has a PDZ domain and is involved in the regulation and recycling of transmembrane proteins. The role of SNX27 on the activity and recycling of the intestinal Cl-/HCO3- exchanger DRA has not yet been studied. This study shows that SNX27 directly interacts with DRA in early endosomes at the apical pole of intestinal Caco2 cells and mediates its direct recycling to facilitate high activity in lipid rafts in the apical plasma membrane.
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Affiliation(s)
- Karen Bannert
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Peggy Berlin
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Johannes Reiner
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Heiko Lemcke
- Department of Cardiac Surgery, Rostock University Medical Center, Rostock, Germany.,Department Life, Light and Matter, University of Rostock, Rostock, Germany
| | - Robert David
- Department of Cardiac Surgery, Rostock University Medical Center, Rostock, Germany.,Department Life, Light and Matter, University of Rostock, Rostock, Germany
| | - Robby Engelmann
- Institute of Immunology, Rostock University Medical Center, Rostock, Germany
| | - Georg Lamprecht
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
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14
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Abstract
Over the past 25 years, successive cloning of SLC34A1, SLC34A2 and SLC34A3, which encode the sodium-dependent inorganic phosphate (Pi) cotransport proteins 2a-2c, has facilitated the identification of molecular mechanisms that underlie the regulation of renal and intestinal Pi transport. Pi and various hormones, including parathyroid hormone and phosphatonins, such as fibroblast growth factor 23, regulate the activity of these Pi transporters through transcriptional, translational and post-translational mechanisms involving interactions with PDZ domain-containing proteins, lipid microdomains and acute trafficking of the transporters via endocytosis and exocytosis. In humans and rodents, mutations in any of the three transporters lead to dysregulation of epithelial Pi transport with effects on serum Pi levels and can cause cardiovascular and musculoskeletal damage, illustrating the importance of these transporters in the maintenance of local and systemic Pi homeostasis. Functional and structural studies have provided insights into the mechanism by which these proteins transport Pi, whereas in vivo and ex vivo cell culture studies have identified several small molecules that can modify their transport function. These small molecules represent potential new drugs to help maintain Pi homeostasis in patients with chronic kidney disease - a condition that is associated with hyperphosphataemia and severe cardiovascular and skeletal consequences.
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15
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Torquati A, Shantavasinkul PC, Omotosho P, Corsino L, Spagnoli A. Perioperative changes in prouroguanylin hormone response in severely obese subjects after bariatric surgery. Surgery 2019; 166:456-459. [PMID: 31472974 DOI: 10.1016/j.surg.2019.06.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 06/22/2019] [Accepted: 06/29/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Prouroguanylin is a gut hormone converted into uroguanylin in the hypothalamus. Uroguanylin induces satiety through guanylyl-cyclase-2C receptor signaling. However, little is known about the role of this hormone in regulating human food intake. METHODS In prospective-cohort study, prouroguanylin profile changes were determined during meal stimulation in obese patients 2 weeks before and 2 weeks after Roux-en-Y gastric bypass surgery. We also investigated whether these changes play a role in the anorexigenic effect of Roux-en-Y gastric bypass. RESULTS The study enrolled 8 healthy lean volunteers and 10 obese patients with type 2 diabetes. Prouroguanylin levels were postprandially decreased at 30 minutes (P = .04) and 60 minutes (P = .008) in obese patients before surgery, and they were increased at 60 minutes (P = .003), 90 minutes (P = .008), and 120 minutes (P = .009) after surgery. We observed a significant difference (P = .001) in fasting prouroguanylin levels before (8.82 ± 1.2 ng/mL) and after (6.05 ± 1.2 ng/mL) Roux-en-Y gastric bypass. Hunger ratings in the fasted state did not change after Roux-en-Y gastric bypass. Instead, subjects demonstrated significantly (P = .01) lower hunger visual analog scale scores than before Roux-en-Y gastric bypass. No correlations between circulating prouroguanylin levels and hunger perception were found before or after Roux-en-Y gastric bypass. CONCLUSION Prouroguanylin levels decrease after meal stimulation in obese patients, and they increase after Roux-en-Y gastric bypass, but no correlations exist with hunger visual analog scale scores.
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Affiliation(s)
| | | | | | - Leonor Corsino
- Division of Endocrinology, Metabolism, and Nutrition, Duke University, Durham, NC
| | - Anna Spagnoli
- Department of Pediatrics, University of Nebraska Medical Center, Omaha
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16
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Palaniappan B, Arthur S, Sundaram VL, Butts M, Sundaram S, Mani K, Singh S, Nepal N, Sundaram U. Inhibition of intestinal villus cell Na/K-ATPase mediates altered glucose and NaCl absorption in obesity-associated diabetes and hypertension. FASEB J 2019; 33:9323-9333. [PMID: 31107610 PMCID: PMC6662973 DOI: 10.1096/fj.201802673r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 04/23/2019] [Indexed: 01/07/2023]
Abstract
During obesity, diabetes and hypertension inevitably coexist and cause innumerable health disparities. In the obesity, diabetes, and hypertension triad (ODHT), deregulation of glucose and NaCl homeostasis, respectively, causes diabetes and hypertension. In the mammalian intestine, glucose is primarily absorbed by Na-glucose cotransport 1 (SGLT1) and coupled NaCl by the dual operation of Na-H exchange 3 (NHE3) and Cl-HCO3 [down-regulated in adenoma (DRA) or putative anion transporter 1 (PAT1)] exchange in the brush border membrane (BBM) of villus cells. The basolateral membrane (BLM) Na/K-ATPase provides the favorable transcellular Na gradient for BBM SGLT1 and NHE3. How these multiple, distinct transport processes may be affected in ODHT is unclear. Here, we show the novel and broad regulation by Na/K-ATPase of glucose and NaCl absorption in ODHT in multiple species (mice, rats, and humans). In vivo, during obesity inhibition of villus-cell BLM, Na/K-ATPase led to compensatory stimulation of BBM SGLT1 and DRA or PAT1, whereas NHE3 was unaffected. Supporting this new cellular adaptive mechanism, direct silencing of BLM Na/K-ATPase in intestinal epithelial cells resulted in selective stimulation of BBM SGLT1 and DRA or PAT1 but not NHE3. These changes will lead to an increase in glucose absorption, maintenance of traditional coupled NaCl absorption, and a de novo increase in NaCl absorption from the novel coupling of stimulated SGLT1 with DRA or PAT1. Thus, these novel observations provide the pathophysiologic basis for the deregulation of glucose and NaCl homeostasis of diabetes and hypertension, respectively, during obesity. These observations may lead to more efficacious treatment for obesity-associated diabetes and hypertension.-Palaniappan, B., Arthur, S., Sundaram, V. L., Butts, M., Sundaram, S., Mani, K., Singh, S., Nepal, N., Sundaram, U. Inhibition of intestinal villus cell Na/K-ATPase mediates altered glucose and NaCl absorption in obesity-associated diabetes and hypertension.
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Affiliation(s)
- Balasubramanian Palaniappan
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Subha Arthur
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Vijaya Lakshmi Sundaram
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Molly Butts
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Shanmuga Sundaram
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Kathiresh Mani
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Soudamani Singh
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Niraj Nepal
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Uma Sundaram
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
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Jeong J, Kim W, Hens J, Dann P, Schedin P, Friedman PA, Wysolmerski JJ. NHERF1 Is Required for Localization of PMCA2 and Suppression of Early Involution in the Female Lactating Mammary Gland. Endocrinology 2019; 160:1797-1810. [PMID: 31087002 PMCID: PMC6619491 DOI: 10.1210/en.2019-00230] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/07/2019] [Indexed: 12/11/2022]
Abstract
Prior studies have demonstrated that the calcium pump, plasma membrane calcium ATPase 2 (PMCA2), mediates calcium transport into milk and prevents mammary epithelial cell death during lactation. PMCA2 also regulates cell proliferation and cell death in breast cancer cells, in part by maintaining the receptor tyrosine kinase ErbB2/HER2 within specialized plasma membrane domains. Furthermore, the regulation of PMCA2 membrane localization and activity in breast cancer cells requires its interaction with the PDZ domain-containing scaffolding molecule sodium-hydrogen exchanger regulatory factor (NHERF) 1. In this study, we asked whether NHERF1 also interacts with PMCA2 in normal mammary epithelial cells during lactation. Our results demonstrate that NHERF1 expression is upregulated during lactation and that it interacts with PMCA2 at the apical membrane of secretory luminal epithelial cells. Similar to PMCA2, NHERF1 expression is rapidly reduced by milk stasis after weaning. Examining lactating NHERF1 knockout (KO) mice showed that NHERF1 contributes to the proper apical location of PMCA2, for proper apical-basal polarity in luminal epithelial cells, and that it participates in the suppression of Stat3 activation and the prevention of premature mammary gland involution. Additionally, we found that PMCA2 also interacts with the closely related scaffolding molecule, NHERF2, at the apical membrane, which likely maintains PMCA2 at the plasma membrane of mammary epithelial cells in lactating NHERF1KO mice. Based on these data, we conclude that, during lactation, NHERF1 is required for the proper expression and apical localization of PMCA2, which, in turn, contributes to preventing the premature activation of Stat3 and the lysosome-mediated cell death pathway that usually occur only early in mammary involution.
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Affiliation(s)
- Jaekwang Jeong
- Section of Endocrinology and Metabolism, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Wonnam Kim
- Division of Pharmacology, College of Korean Medicine, Semyung University, Jecheon, Republic of Korea
| | - Julie Hens
- Section of Endocrinology and Metabolism, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Pamela Dann
- Section of Endocrinology and Metabolism, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Pepper Schedin
- Department of Cell, Developmental, and Cancer Biology, Oregon Health and Science University, Portland, Oregon
| | - Peter A Friedman
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - John J Wysolmerski
- Section of Endocrinology and Metabolism, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
- Correspondence: John J. Wysolmerski, MD, Section of Endocrinology and Metabolism, Department of Internal Medicine, TAC S123a, Yale University School of Medicine, 333 Cedar Street, FMT 102, Box 208020, New Haven, Connecticut 06520. E-mail:
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18
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Chen T, Lin R, Avula L, Sarker R, Yang J, Cha B, Tse CM, McNamara G, Seidler U, Waldman S, Snook A, Bijvelds MJC, de Jonge HR, Li X, Donowitz M. NHERF3 is necessary for Escherichia coli heat-stable enterotoxin-induced inhibition of NHE3: differences in signaling in mouse small intestine and Caco-2 cells. Am J Physiol Cell Physiol 2019; 317:C737-C748. [PMID: 31365292 DOI: 10.1152/ajpcell.00351.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a leading cause of childhood death from diarrhea and the leading cause of Traveler's diarrhea. E. coli heat-stable enterotoxin (ST) is a major virulence factor of ETEC and inhibits the brush border Na/H exchanger NHE3 in producing diarrhea. NHE3 regulation involves multiprotein signaling complexes that form on its COOH terminus. In this study, the hypothesis was tested that ST signals via members of the Na/H exchanger regulatory factor (NHERF) family of scaffolding proteins, NHERF2, which had been previously shown to have a role, and now with concentration on a role for NHERF3. Two models were used: mouse small intestine and Caco-2/BBe cells. In both models, ST rapidly increased intracellular cGMP, inhibited NHE3 activity, and caused a quantitatively similar decrease in apical expression of NHE3. The transport effects were NHERF3 and NHERF2 dependent. Also, mutation of the COOH-terminal amino acids of NHERF3 supported that NHERF3-NHERF2 heterodimerization was likely to account for this dual dependence. The ST increase in cGMP in both models was partially dependent on NHERF3. The intracellular signaling pathways by which ST-cGMP inhibits NHE3 were different in mouse jejunum (activation of cGMP kinase II, cGKII) and Caco-2 cells, which do not express cGKII (elevation of intracellular Ca2+ concentration [Ca2+]i). The ST elevation of [Ca2+]i was from intracellular stores and was dependent on NHERF3-NHERF2. This study shows that intracellular signaling in the same diarrheal model in multiple cell types may be different; this has implications for therapeutic strategies, which often assume that models have similar signaling mechanisms.
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Affiliation(s)
- Tiane Chen
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ruxian Lin
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Leela Avula
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Rafiquel Sarker
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jianbo Yang
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Boyoung Cha
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chung Ming Tse
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - George McNamara
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Scott Waldman
- Division of Clinical Pharmacology, Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Adam Snook
- Division of Clinical Pharmacology, Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Marcel J C Bijvelds
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Hugo R de Jonge
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Xuhang Li
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mark Donowitz
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Saponaro C, Scarpi E, Zito FA, Giotta F, Silvestris N, Mangia A. Independent Negative Prognostic Role of TCF1 Expression within the Wnt/β-Catenin Signaling Pathway in Primary Breast Cancer Patients. Cancers (Basel) 2019; 11:cancers11071035. [PMID: 31336689 PMCID: PMC6678184 DOI: 10.3390/cancers11071035] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/09/2019] [Accepted: 07/19/2019] [Indexed: 12/21/2022] Open
Abstract
The Wnt pathway is involved in the progression of breast cancer (BC). We aimed to evaluate the expression of some components of the Wnt pathway (β-catenin, FZD4 (frizzled receptor 4), LRP5 (low-density lipoprotein receptor-related protein 5), LRP6, and TCF1 (T-cell factor 1)) to detect potential associations with NHERF1 (Na+/H+ exchanger regulatory factor 1) protein. Besides, we assessed their impact on patients’ clinical outcome. We evaluated 220 primary BC samples by immunohistochemistry (IHC) and protein localization by immunofluorescence. We found a significant correlation between NHERF1 and FZD4, LRP5, LRP6, and TCF1. Univariate analysis showed that the overexpression of β-catenin (p < 0.0001), FZD4 (p = 0.0001), LRP5, LRP6, and TCF1 (p < 0.0001 respectively) was related to poor disease-free survival (DFS). A Kaplan-Meier analysis confirmed univariate data and showed a poor DFS for cNHERF1+/FZD4+ (p = 0.0007), cNHERF1+/LRP5+ (p = 0.0002), cNHERF1+/LRP6+ (p < 0.0001), and cNHERF1+/TCF1+ phenotypes (p = 0.0034). In multivariate analysis, the expression of TCF1 and β-catenin was an independent prognostic variable of worse DFS (p = 0.009 and p = 0.027, respectively). In conclusion, we found that the overexpression of β-catenin, FZD4, LRP5, LRP6, and TCF1 was associated with poor prognosis. Furthermore, we first identified TCF1 as an independent prognostic factor of poor outcome, indicating it as a new potential biomarker for the management of BC patients. Also, the expression of Wnt pathway proteins, both alone and in association with NHERF1, suggests original associations of biological significance for new studies.
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Affiliation(s)
- Concetta Saponaro
- Functional Biomorphology Laboratory, IRCCS Istituto Tumori "Giovanni Paolo II" of Bari, 70124 Bari, Italy
| | - Emanuela Scarpi
- Unit of Biostatistics and Clinical Trials, (IRST)-IRCCS Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori, 47014 Meldola (FC), Italy
| | - Francesco Alfredo Zito
- Pathology Department, IRCCS Istituto Tumori "Giovanni Paolo II" of Bari, 70124 Bari, Italy
| | - Francesco Giotta
- Medical Oncology Unit, IRCCS-Istituto Tumori "Giovanni Paolo II" of Bari, 70124 Bari, Italy
| | - Nicola Silvestris
- Medical Oncology Unit, IRCCS-Istituto Tumori "Giovanni Paolo II" of Bari, 70124 Bari, Italy.
- Department of Biomedical Sciences and Human Oncology, University of Bari 'Aldo Moro', 70124 Bari, Italy.
| | - Anita Mangia
- Functional Biomorphology Laboratory, IRCCS Istituto Tumori "Giovanni Paolo II" of Bari, 70124 Bari, Italy.
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Zhao C, Tao T, Yang L, Qin Q, Wang Y, Liu H, Song R, Yang X, Wang Q, Gu S, Xiong Y, Zhao D, Wang S, Feng D, Jiang WG, Zhang J, He J. Loss of PDZK1 expression activates PI3K/AKT signaling via PTEN phosphorylation in gastric cancer. Cancer Lett 2019; 453:107-121. [DOI: 10.1016/j.canlet.2019.03.043] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 03/21/2019] [Accepted: 03/22/2019] [Indexed: 02/07/2023]
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Rao MC. Physiology of Electrolyte Transport in the Gut: Implications for Disease. Compr Physiol 2019; 9:947-1023. [PMID: 31187895 DOI: 10.1002/cphy.c180011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We now have an increased understanding of the genetics, cell biology, and physiology of electrolyte transport processes in the mammalian intestine, due to the availability of sophisticated methodologies ranging from genome wide association studies to CRISPR-CAS technology, stem cell-derived organoids, 3D microscopy, electron cryomicroscopy, single cell RNA sequencing, transgenic methodologies, and tools to manipulate cellular processes at a molecular level. This knowledge has simultaneously underscored the complexity of biological systems and the interdependence of multiple regulatory systems. In addition to the plethora of mammalian neurohumoral factors and their cross talk, advances in pyrosequencing and metagenomic analyses have highlighted the relevance of the microbiome to intestinal regulation. This article provides an overview of our current understanding of electrolyte transport processes in the small and large intestine, their regulation in health and how dysregulation at multiple levels can result in disease. Intestinal electrolyte transport is a balance of ion secretory and ion absorptive processes, all exquisitely dependent on the basolateral Na+ /K+ ATPase; when this balance goes awry, it can result in diarrhea or in constipation. The key transporters involved in secretion are the apical membrane Cl- channels and the basolateral Na+ -K+ -2Cl- cotransporter, NKCC1 and K+ channels. Absorption chiefly involves apical membrane Na+ /H+ exchangers and Cl- /HCO3 - exchangers in the small intestine and proximal colon and Na+ channels in the distal colon. Key examples of our current understanding of infectious, inflammatory, and genetic diarrheal diseases and of constipation are provided. © 2019 American Physiological Society. Compr Physiol 9:947-1023, 2019.
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Affiliation(s)
- Mrinalini C Rao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois, USA
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22
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Palaniappan B, Manoharan P, Arthur S, Singh S, Murughiyan U, Sundaram U. Stimulation of constitutive nitric oxide uniquely and compensatorily regulates intestinal epithelial cell brush border membrane Na absorption. Physiol Rep 2019; 7:e14086. [PMID: 31074207 PMCID: PMC6509550 DOI: 10.14814/phy2.14086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 04/10/2019] [Accepted: 04/12/2019] [Indexed: 02/04/2023] Open
Abstract
In the mammalian small intestine, sodium is primarily absorbed by Na+ /H+ exchange (NHE3) and Na-glucose cotransport (SGLT1) in the brush border membrane (BBM) of villus cells. However, how enhanced cellular constitutive nitric oxide (cNO) may affect NHE3 and SGLT1 remains unclear. Both in vivo in rabbit intestinal villus cells and in vitro IEC-18 cells, administration of NO donor, GSNAP, modestly increased cNO. GSNAP stimulated SGLT1 in villus and IEC-18 cells. The mechanism of stimulation was secondary to an increase in the affinity of SGLT1 for glucose. The change in SGLT1 was not secondary to altered Na-extruding capacity of the cell since Na+ /K+ -ATPase was decreased by GSNAP treatment. In contrast, GSNAP inhibited NHE3 activity in villus cell BBM. The mechanism of NHE3 inhibition was secondary to reduced BBM transporter numbers. These studies demonstrated that the physiological increase in cNO uniquely regulates mammalian small intestinal NHE3 and SGLT1 to maintain Na homeostasis.
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Affiliation(s)
- Balasubramanian Palaniappan
- Department of Clinical and Translational SciencesJoan C Edwards School of MedicineMarshall UniversityHuntingtonWest Virginia
| | - Palanikumar Manoharan
- Department of Clinical and Translational SciencesJoan C Edwards School of MedicineMarshall UniversityHuntingtonWest Virginia
| | - Subha Arthur
- Department of Clinical and Translational SciencesJoan C Edwards School of MedicineMarshall UniversityHuntingtonWest Virginia
| | - Soudamani Singh
- Department of Clinical and Translational SciencesJoan C Edwards School of MedicineMarshall UniversityHuntingtonWest Virginia
| | - Usha Murughiyan
- Department of Clinical and Translational SciencesJoan C Edwards School of MedicineMarshall UniversityHuntingtonWest Virginia
| | - Uma Sundaram
- Department of Clinical and Translational SciencesJoan C Edwards School of MedicineMarshall UniversityHuntingtonWest Virginia
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23
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Seidler U, Nikolovska K. Slc26 Family of Anion Transporters in the Gastrointestinal Tract: Expression, Function, Regulation, and Role in Disease. Compr Physiol 2019; 9:839-872. [DOI: 10.1002/cphy.c180027] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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24
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McHugh DR, Cotton CU, Moss FJ, Vitko M, Valerio DM, Kelley TJ, Hao S, Jafri A, Drumm ML, Boron WF, Stern RC, McBennett K, Hodges CA. Linaclotide improves gastrointestinal transit in cystic fibrosis mice by inhibiting sodium/hydrogen exchanger 3. Am J Physiol Gastrointest Liver Physiol 2018; 315:G868-G878. [PMID: 30118317 PMCID: PMC9925117 DOI: 10.1152/ajpgi.00261.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gastrointestinal dysfunction in cystic fibrosis (CF) is a prominent source of pain among patients with CF. Linaclotide, a guanylate cyclase C (GCC) receptor agonist, is a US Food and Drug Administration-approved drug prescribed for chronic constipation but has not been widely used in CF, as the cystic fibrosis transmembrane conductance regulator (CFTR) is the main mechanism of action. However, anecdotal clinical evidence suggests that linaclotide may be effective for treating some gastrointestinal symptoms in CF. The goal of this study was to determine the effectiveness and mechanism of linaclotide in treating CF gastrointestinal disorders using CF mouse models. Intestinal transit, chloride secretion, and intestinal lumen fluidity were assessed in wild-type and CF mouse models in response to linaclotide. CFTR and sodium/hydrogen exchanger 3 (NHE3) response to linaclotide was also evaluated. Linaclotide treatment improved intestinal transit in mice carrying either F508del or null Cftr mutations but did not induce detectable Cl- secretion. Linaclotide increased fluid retention and fluidity of CF intestinal contents, suggesting inhibition of fluid absorption. Targeted inhibition of sodium absorption by the NHE3 inhibitor tenapanor produced improvements in gastrointestinal transit similar to those produced by linaclotide treatment, suggesting that inhibition of fluid absorption by linaclotide contributes to improved gastrointestinal transit in CF. Our results demonstrate that linaclotide improves gastrointestinal transit in CF mouse models by increasing luminal fluidity through inhibiting NHE3-mediated sodium absorption. Further studies are necessary to assess whether linaclotide could improve CF intestinal pathologies in patients. GCC signaling and NHE3 inhibition may be therapeutic targets for CF intestinal manifestations. NEW & NOTEWORTHY Linaclotide's primary mechanism of action in alleviating chronic constipation is through cystic fibrosis transmembrane conductance regulator (CFTR), negating its use in patients with cystic fibrosis (CF). For the first time, our findings suggest that in the absence of CFTR, linaclotide can improve fluidity of the intestinal lumen through the inhibition of sodium/hydrogen exchanger 3. These findings suggest that linaclotide could improve CF intestinal pathologies in patients.
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Affiliation(s)
- Daniel R. McHugh
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Calvin U. Cotton
- 2Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio,3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Fraser J. Moss
- 2Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Megan Vitko
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Dana M. Valerio
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Thomas J. Kelley
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio,4Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Shuyu Hao
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Anjum Jafri
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Mitchell L. Drumm
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio,3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Walter F. Boron
- 2Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio,5Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio,6Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Robert C. Stern
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio,7Rainbow Babies and Children’s Hospital, Cleveland, Ohio
| | - Kimberly McBennett
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio,7Rainbow Babies and Children’s Hospital, Cleveland, Ohio
| | - Craig A. Hodges
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio,3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
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25
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Pelaseyed T, Bretscher A. Regulation of actin-based apical structures on epithelial cells. J Cell Sci 2018; 131:131/20/jcs221853. [PMID: 30333133 DOI: 10.1242/jcs.221853] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cells of transporting epithelia are characterized by the presence of abundant F-actin-based microvilli on their apical surfaces. Likewise, auditory hair cells have highly reproducible rows of apical stereocilia (giant microvilli) that convert mechanical sound into an electrical signal. Analysis of mutations in deaf patients has highlighted the critical components of tip links between stereocilia, and related structures that contribute to the organization of microvilli on epithelial cells have been found. Ezrin/radixin/moesin (ERM) proteins, which are activated by phosphorylation, provide a critical link between the plasma membrane and underlying actin cytoskeleton in surface structures. Here, we outline recent insights into how microvilli and stereocilia are built, and the roles of tip links. Furthermore, we highlight how ezrin is locally regulated by phosphorylation, and that this is necessary to maintain polarity. Localized phosphorylation is achieved through an intricate coincidence detection mechanism that requires the membrane lipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and the apically localized ezrin kinase, lymphocyte-oriented kinase (LOK, also known as STK10) or Ste20-like kinase (SLK). We also discuss how ezrin-binding scaffolding proteins regulate microvilli and how, despite these significant advances, it remains to be discovered how the cell polarity program ultimately interfaces with these processes.
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Affiliation(s)
- Thaher Pelaseyed
- Institute of Biomedicine, Department of Medical Biochemistry and Cell Biology, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Anthony Bretscher
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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26
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Trimarchi H, Canzonieri R, Costales-Collaguazo C, Politei J, Stern A, Paulero M, González-Hoyos I, Schiel A, Rengel T, Forrester M, Lombi F, Pomeranz V, Iriarte R, Muryan A, Zotta E. Early decrease in the podocalyxin to synaptopodin ratio in urinary Fabry podocytes. Clin Kidney J 2018; 12:53-60. [PMID: 30747154 PMCID: PMC6366138 DOI: 10.1093/ckj/sfy053] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 05/24/2018] [Indexed: 12/20/2022] Open
Abstract
Background In Fabry nephropathy, podocyturia is an early event that may lead to glomerulosclerosis and chronic kidney disease. The glycocalyx is a potential podocyte damaged compartment in glomerulopathies. We investigated glycocalyx podocalyxin in urinary detached podocytes compared with cytoplasmic synaptopodin. Methods This was a cross-sectional study including 68 individuals: Controls (n = 20) and Fabry patients (n = 48), 15 untreated and 33 treated. Variables included age, gender, urinary protein/creatinine ratio (UPCR), estimated glomerular filtration rate (eGFR), lyso-triasocylsphingosine (lyso-Gb3) levels and enzyme replacement therapy (ERT). Podocyturia was assessed by immunofluorescence and podocyte subpopulations were analyzed. Results Fabry patients displayed higher podocyturia than controls. Fabry treated subjects (n = 33) presented significantly higher UPCR compared with untreated ones (n = 15); podocyturia, eGFR and lyso-Gb3 levels were not different. All control podocytes colocalized synaptopodin and podocalyxin; 13 Fabry patients (27%) colocalized these proteins, while 35 (73%) were only synaptopodin positive. No podocalyxin-positive/synaptopodin-negative cells were encountered. In Fabry patients, podocyturia was significantly higher and proteinuria lower in those that colocalized. Conclusion Fabry patients present higher podocyturia and a presumably more damaged glycocalyx assessed by podocalyxin. Treated patients had significant higher proteinuria suggesting ERT is initiated late, at advanced stages. The degree of podocalyxin-negative podocytes was similar in both groups, but colocalization was associated with lower proteinuria. Podocyturia assessed by podocalyxin alone may be underestimated. The implications of podocyte glycocalyx damage deserve further investigations.
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Affiliation(s)
- Hernán Trimarchi
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Romina Canzonieri
- Central Laboratory, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Cristian Costales-Collaguazo
- IFIBIO Houssay, CONICET, Physiopathology, Pharmacy and Biochemistry Faculty, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Juan Politei
- Neurology Department, Laboratorio Neuroquímica Dr Néstor Chamoles Buenos Aires, Buenos Aires, Argentina
| | - Anibal Stern
- Central Laboratory, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Matias Paulero
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Ivan González-Hoyos
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Amalia Schiel
- Central Laboratory, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Tatiana Rengel
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Mariano Forrester
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Fernando Lombi
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Vanesa Pomeranz
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Romina Iriarte
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Alexis Muryan
- Central Laboratory, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Elsa Zotta
- IFIBIO Houssay, CONICET, Physiopathology, Pharmacy and Biochemistry Faculty, Universidad de Buenos Aires, Buenos Aires, Argentina
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27
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Li J, He Q, Li Q, Huang R, Wei X, Pan X, Wu W. Decreased expression of Na+-H+ exchanger isoforms 1 and 3 in denervated spontaneously hypertensive rat kidney. Clin Exp Hypertens 2018; 41:235-243. [PMID: 29787310 DOI: 10.1080/10641963.2018.1469639] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Jianling Li
- Department of Cardiology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Qiaoling He
- Department of Pharmacology, Affiliated Hospital of Guangxi Medical University, The First people’s Hospital of Nanning, Nanning, China
| | - Qingjie Li
- Department of Cardiology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Rongjie Huang
- Department of Pharmacology, Affiliated Hospital of Guangxi Medical University, The First people’s Hospital of Nanning, Nanning, China
| | - Xiaoyan Wei
- Department of Pharmacology, Affiliated Hospital of Guangxi Medical University, The First people’s Hospital of Nanning, Nanning, China
| | - Xiaofeng Pan
- Department of Cardiology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Weifeng Wu
- Department of Cardiology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
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28
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Shen WJ, Asthana S, Kraemer FB, Azhar S. Scavenger receptor B type 1: expression, molecular regulation, and cholesterol transport function. J Lipid Res 2018; 59:1114-1131. [PMID: 29720388 DOI: 10.1194/jlr.r083121] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/26/2018] [Indexed: 12/16/2022] Open
Abstract
Cholesterol is required for maintenance of plasma membrane fluidity and integrity and for many cellular functions. Cellular cholesterol can be obtained from lipoproteins in a selective pathway of HDL-cholesteryl ester (CE) uptake without parallel apolipoprotein uptake. Scavenger receptor B type 1 (SR-B1) is a cell surface HDL receptor that mediates HDL-CE uptake. It is most abundantly expressed in liver, where it provides cholesterol for bile acid synthesis, and in steroidogenic tissues, where it delivers cholesterol needed for storage or steroidogenesis in rodents. SR-B1 transcription is regulated by trophic hormones in the adrenal gland, ovary, and testis; in the liver and elsewhere, SR-B1 is subject to posttranscriptional and posttranslational regulation. SR-B1 operates in several metabolic processes and contributes to pathogenesis of atherosclerosis, inflammation, hepatitis C virus infection, and other conditions. Here, we summarize characteristics of the selective uptake pathway and involvement of microvillar channels as facilitators of selective HDL-CE uptake. We also present the potential mechanisms of SR-B1-mediated selective cholesterol transport; the transcriptional, posttranscriptional, and posttranslational regulation of SR-B1; and the impact of gene variants on expression and function of human SR-B1. A better understanding of this unique pathway and SR-B1's role may yield improved therapies for a wide variety of conditions.
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Affiliation(s)
- Wen-Jun Shen
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
| | - Shailendra Asthana
- Drug Discovery Research Center (DDRC), Translational Health Science and Technology Institute (THSTI), NCR Biotech Science Cluster, Faridabad 121001, Haryana, India
| | - Fredric B Kraemer
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
| | - Salman Azhar
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
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Bergsland KJ, Coe FL, Parks JH, Asplin JR, Worcester EM. Evidence for a role of PDZ domain-containing proteins to mediate hypophosphatemia in calcium stone formers. Nephrol Dial Transplant 2018; 33:759-770. [PMID: 29126251 DOI: 10.1093/ndt/gfx284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 08/29/2017] [Indexed: 01/26/2023] Open
Abstract
Background Hypophosphatemia (HYP) is common among calcium stone formers (SFs) and in rare cases is associated with mutations in sodium-phosphate cotransporters or in Na+/H+ exchanger regulatory factor 1 (NHERF1), but the majority of cases are unexplained. We hypothesized that reduced sodium-phosphate cotransporter activity mediated via NHERF1 or a similar PDZ domain-containing protein, causes HYP. If so, other transport activities controlled by NHERF1, such as NHE3 and URAT1, might be reduced in HYP. Methods To test this idea, we analyzed two large but separate sets of 24-h urine samples and paired serums of 2700 SFs from the University of Chicago and 11 073 SFs from Litholink, a national laboratory. Patients were divided into quintiles based on serum phosphate. Results Males were more common in the lowest phosphate tiles in both datasets. Phosphate excretion did not vary across the quintiles, excluding diet as a cause of HYP. Tubule maximum (Tm) phosphate per unit glomerular filtration rate decreased and fractional excretion increased with decreasing phosphate quintiles, indicating reduced tubule phosphate reabsorption was responsible for HYP. Urine pH and serum chloride increased with decreasing serum phosphate, suggesting a coordinate change in NHE3 activity. Serum uric acid and Tm uric acid decreased significantly with decreasing serum phosphate, while uric acid excretion did not vary. Conclusion. HYP in SFs results from decreased tubule phosphate reabsorption and, being associated with related changes in other proximal tubule transporters, may arise from alterations in or signaling to PDZ-containing proteins.
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Affiliation(s)
| | - Fredric L Coe
- Department of Medicine, University of Chicago, Chicago, IL, USA
| | - Joan H Parks
- Department of Medicine, University of Chicago, Chicago, IL, USA
| | - John R Asplin
- Litholink Corporation, Laboratory Corporation of America Holdings, Chicago, IL, USA
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Direct and specific inhibition of constitutive nitric oxide synthase uniquely regulates brush border membrane Na-absorptive pathways in intestinal epithelial cells. Nitric Oxide 2018; 79:8-13. [PMID: 29702252 DOI: 10.1016/j.niox.2018.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/20/2018] [Accepted: 04/23/2018] [Indexed: 01/01/2023]
Abstract
Pharmacological manipulations of constitutive nitric oxide (cNO) levels have been shown to have variable effects on Na absorption in vivo and in vitro in different tissues. Species differences, untoward in vivo effects (e.g. ENS, blood flow) and pharmacological non-specificity may account for these confounding observations. Thus, to directly and specifically determine the effect of cNO on brush border membrane Na/H exchange (NHE3) and Na-dependent glucose co-transport (SGLT-1), we inhibited cNO synthase (NOS3) with its siRNA in rat small intestinal epithelial cells (IEC-18) in vitro. As expected, intracellular cNO levels were reduced in siRNA NOS3 transfected cells. In these cells, SGLT-1 was significantly reduced compared to control. In contrast, NHE3 was significantly increased in siRNA NOS3 transfected cells. To determine if SGLT-1 changes were secondary to altered Na/K-ATPase, its activity was measured and found to be increased in NOS3 silenced cells. The mechanism of inhibition of SGLT-1 was secondary to diminished affinity of the co-transporter for glucose in NOS3 silenced cells. In contrast, the mechanism of stimulation of NHE3 is by increasing BBM exchanger numbers in siRNA NOS3 cells while the affinity was unaffected. Western blot studies of immunoreactive BBM proteins also confirmed the kinetic studies. All these data indicates that direct and specific inhibition of NOS3 with its siRNA inhibits SGLT-1 while stimulating NHE3 in the BBM. Thus, cNO uniquely and compensatorily regulates BBM NHE3 and SGLT-1 to maintain cellular Na homeostasis and these unique alterations by cNO are mediated by its intracellular 2nd messenger cGMP.
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31
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Kralicek SE, Nguyen M, Rhee KJ, Tapia R, Hecht G. EPEC NleH1 is significantly more effective in reversing colitis and reducing mortality than NleH2 via differential effects on host signaling pathways. J Transl Med 2018; 98:477-488. [PMID: 29396422 PMCID: PMC5920738 DOI: 10.1038/s41374-017-0016-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 11/21/2017] [Accepted: 11/27/2017] [Indexed: 12/31/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) is a foodborne pathogen that uses a type III secretion system to translocate effector molecules into host intestinal epithelial cells (IECs) subverting several host cell processes and signaling cascades. Interestingly, EPEC infection induces only modest intestinal inflammation in the host. The homologous EPEC effector proteins, NleH1 and NleH2, suppress the nuclear factor-κB (NF-κB) pathway and apoptosis in vitro. Increased apoptosis and activation of NF-κB and MAP kinases (MAPK) contribute to the pathogenesis of inflammatory bowel diseases (IBD). The aim of this study was to determine if NleH1 and NleH2 also block MAPK pathways in vitro and in vivo, and to compare the effects of these bacterial proteins on a murine model of colitis. Cultured IECs were infected with various strains of EPEC expressing NleH1 and NleH2, or not, and the activation of ERK1/2 and p38 was determined. In addition, the impact of infection with various strains of EPEC on murine DSS colitis was assessed by change in body weight, colon length, histology, and survival. Activation of apoptosis and MAPK signaling were also evaluated. Our data show that NleH1, but not NleH2, suppresses ERK1/2 and p38 activation in vitro. Interestingly, NleH1 affords significantly greater protection against and hastens recovery from dextran sodium sulfate (DSS)-induced colitis compared to NleH2. Strikingly, colitis-associated mortality was abolished by infection with EPEC strains expressing NleH1. Interestingly, in vivo NleH1 suppresses activation of ERK1/2 and p38 and blocks apoptosis independent of the kinase domain that inhibits NF-κB. In contrast, NleH2 suppresses only caspase-3 and p38, but not ERK1/2. We conclude that NleH1 affords greater protection against and improves recovery from DSS colitis compared to NleH2 due to its ability to suppress ERK1/2 in addition to NF-κB, p38, and apoptosis. These findings warrant further investigation of anti-inflammatory bacterial proteins as novel treatments for IBD.
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Affiliation(s)
- Sarah E. Kralicek
- Department of Medicine, Division of Gastroenterology and Nutrition, Loyola University Chicago, Maywood, IL, USA
| | - Mai Nguyen
- Cortexyme Inc, South San Francisco, CA, USA
| | - Ki-Jong Rhee
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University at Wonju, Wonju, Gangwon-do, Republic of Korea
| | - Rocio Tapia
- Department of Medicine, Division of Gastroenterology and Nutrition, Loyola University Chicago, Maywood, IL, USA
| | - Gail Hecht
- Department of Medicine, Division of Gastroenterology and Nutrition, Loyola University Chicago, Maywood, IL, USA. .,Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA. .,Edward Hines Jr. VA Hospital, Hines, IL, USA.
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32
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Avula LR, Chen T, Kovbasnjuk O, Donowitz M. Both NHERF3 and NHERF2 are necessary for multiple aspects of acute regulation of NHE3 by elevated Ca 2+, cGMP, and lysophosphatidic acid. Am J Physiol Gastrointest Liver Physiol 2018; 314:G81-G90. [PMID: 28882822 PMCID: PMC5866371 DOI: 10.1152/ajpgi.00140.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The intestinal epithelial brush border Na+/H+ exchanger NHE3 accounts for a large component of intestinal Na absorption. NHE3 is regulated during digestion by signaling complexes on its COOH terminus that include the four multi-PDZ domain-containing NHERF family proteins. All bind to NHE3 and take part in different aspects of NHE3 regulation. Because the roles of each NHERF appear to vary on the basis of the cell model or intestinal segment studied and because of our recent finding that a NHERF3-NHERF2 heterodimer appears important for NHE3 regulation in Caco-2 cells, we examined the role of NHERF3 and NHERF2 in C57BL/6 mouse jejunum using homozygous NHERF2 and NHERF3 knockout mice. NHE3 activity was determined with two-photon microscopy and the dual-emission pH-sensitive dye SNARF-4F. The jejunal apical membrane of NHERF3-null mice appeared similar to wild-type (WT) mice in surface area, microvillus number, and height, which is similar to results previously reported for jejunum of NHERF2-null mice. NHE3 basal activity was not different from WT in either NHERF2- or NHERF3-null jejunum, while d-glucose-stimulated NHE3 activity was reduced in NHERF2, but similar to WT in NHERF3 KO. LPA stimulation and UTP (elevated Ca2+) and cGMP inhibition of NHE3 were markedly reduced in both NHERF2- and NHERF3-null jejunum. Forskolin inhibited NHE3 in NHERF3-null jejunum, but the extent of inhibition was reduced compared with WT. The forskolin inhibition of NHE3 in NHERF2-null mice was too inconsistent to determine whether there was an effect and whether it was altered compared with the WT response. These results demonstrate similar requirement for NHERF2 and NHERF3 in mouse jejunal NHE3 regulation by LPA, Ca2+, and cGMP. The explanation for the similarity is not known but is consistent with involvement of a brush-border NHERF3-NHERF2 heterodimer or sequential NHERF-dependent effects in these aspects of NHE3 regulation. NEW & NOTEWORTHY NHERF2 and NHERF3 are apical membrane multi-PDZ domain-containing proteins that are involved in regulation of intestinal NHE3. This study demonstrates that NHERF2 and NHERF3 have overlapping roles in NHE3 stimulation by LPA and inhibition by elevated Ca2+ and cGMP. These results are consistent with their role being as a NHERF3-NHERF2 heterodimer or via sequential NHERF-dependent signaling steps, and they begin to clarify a role for multiple NHERF proteins in NHE3 regulation.
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Affiliation(s)
- Leela Rani Avula
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Tiane Chen
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Olga Kovbasnjuk
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Mark Donowitz
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland,2Department of Physiology, the Johns Hopkins University School of Medicine, Baltimore, Maryland
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33
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Tong M, Yi L, Sun N, Cheng Y, Cao Z, Wang J, Li S, Lin P, Sun Y, Cheng S. Quantitative Analysis of Cellular Proteome Alterations in CDV-Infected Mink Lung Epithelial Cells. Front Microbiol 2017; 8:2564. [PMID: 29312244 PMCID: PMC5743685 DOI: 10.3389/fmicb.2017.02564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 12/11/2017] [Indexed: 12/14/2022] Open
Abstract
Canine distemper virus (CDV), a paramyxovirus, causes a severe highly contagious lethal disease in carnivores, such as mink. Mink lung epithelial cells (Mv.1.Lu cells) are sensitive to CDV infection and are homologous to the natural host system of mink. The current study analyzed the response of Mv.1.Lu cells to CDV infection by iTRAQ combined with LC-MS/MS. In total, 151 and 369 differentially expressed proteins (DEPs) were markedly up-regulated or down-regulated, respectively. Thirteen DEPs were validated via real-time RT-PCR or western blot analysis. Network and KEGG pathway analyses revealed several regulated proteins associated with the NF-κB signaling pathway. Further validation was performed by western blot analysis and immunofluorescence assay, which demonstrated that different CDV strains induced NF-κB P65 phosphorylation and nuclear translocation. Moreover, the results provided interesting information that some identified DEPs possibly associated with the pathogenesis and the immune response upon CDV infection. This study is the first overview of the responses to CDV infection in Mv.1.Lu cells, and the findings will help to analyze further aspects of the molecular mechanisms involved in viral pathogenesis and the immune responses upon CDV infection.
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Affiliation(s)
- Mingwei Tong
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Li Yi
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Na Sun
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Yuening Cheng
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Zhigang Cao
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Jianke Wang
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Shuang Li
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Peng Lin
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Yaru Sun
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Shipeng Cheng
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Economic Animal and Plant Science, Chinese Academy of Agricultural Sciences, Changchun, China
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Li W, Jin WW, Tsuji K, Chen Y, Nomura N, Su L, Yui N, Arthur J, Cotecchia S, Paunescu TG, Brown D, Lu HAJ. Ezrin directly interacts with AQP2 and promotes its endocytosis. J Cell Sci 2017; 130:2914-2925. [PMID: 28754689 DOI: 10.1242/jcs.204842] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/21/2017] [Indexed: 11/20/2022] Open
Abstract
The water channel aquaporin-2 (AQP2) is a major regulator of water homeostasis in response to vasopressin (VP). Dynamic trafficking of AQP2 relies on its close interaction with trafficking machinery proteins and the actin cytoskeleton. Here, we report the identification of ezrin, an actin-binding protein from the ezrin/radixin/moesin (ERM) family as an AQP2-interacting protein. Ezrin was first detected in a co-immunoprecipitation (co-IP) complex using an anti-AQP2 antibody in a proteomic analysis. Immunofluorescence staining revealed the co-expression of ezrin and AQP2 in collecting duct principal cells, and VP treatment caused redistribution of both proteins to the apical membrane. The ezrin-AQP2 interaction was confirmed by co-IP experiments with an anti-ezrin antibody, and by pulldown assays using purified full-length and FERM domain-containing recombinant ezrin. By using purified recombinant proteins, we showed that ezrin directly interacts with AQP2 C-terminus through its N-terminal FERM domain. Knocking down ezrin expression with shRNA resulted in increased membrane accumulation of AQP2 and reduced AQP2 endocytosis. Therefore, through direct interaction with AQP2, ezrin facilitates AQP2 endocytosis, thus linking the dynamic actin cytoskeleton network with AQP2 trafficking.
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Affiliation(s)
- Wei Li
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - William W Jin
- Washington University in St. Louis, College of Arts and Sciences, St Louis, MO 63130, USA
| | - Kenji Tsuji
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Ying Chen
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Naohiro Nomura
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Limin Su
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA.,Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Naofumi Yui
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Julian Arthur
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Susanna Cotecchia
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne 1005, Switzerland
| | - Teodor G Paunescu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Dennis Brown
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Hua A J Lu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
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35
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Oh YS, Heo K, Kim EK, Jang JH, Bae SS, Park JB, Kim YH, Song M, Kim SR, Ryu SH, Kim IH, Suh PG. Dynamic relocalization of NHERF1 mediates chemotactic migration of ovarian cancer cells toward lysophosphatidic acid stimulation. Exp Mol Med 2017; 49:e351. [PMID: 28684865 PMCID: PMC5565956 DOI: 10.1038/emm.2017.88] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 12/28/2016] [Accepted: 01/09/2017] [Indexed: 01/05/2023] Open
Abstract
NHERF1/EBP50 (Na+/H+ exchanger regulating
factor 1; Ezrin-binding phosphoprotein of 50 kDa) organizes stable
protein complexes beneath the apical membrane of polar epithelial cells. By
contrast, in cancer cells without any fixed polarity, NHERF1 often localizes in
the cytoplasm. The regulation of cytoplasmic NHERF1 and its role in cancer
progression remain unclear. In this study, we found that, upon lysophosphatidic
acid (LPA) stimulation, cytoplasmic NHERF1 rapidly translocated to the plasma
membrane, and subsequently to cortical protrusion structures, of ovarian cancer
cells. This movement depended on direct binding of NHERF1 to C-terminally
phosphorylated ERM proteins (cpERMs). Moreover, NHERF1 depletion downregulated
cpERMs and further impaired cpERM-dependent remodeling of the cell cortex,
suggesting reciprocal regulation between these proteins. The LPA-induced protein
complex was highly enriched in migratory pseudopodia, whose formation was
impaired by overexpression of NHERF1 truncation mutants. Consistent with this,
NHERF1 depletion in various types of cancer cells abolished chemotactic cell
migration toward a LPA gradient. Taken together, our findings suggest that the
high dynamics of cytosolic NHERF1 provide cancer cells with a means of
controlling chemotactic migration. This capacity is likely to be essential for
ovarian cancer progression in tumor microenvironments containing LPA.
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Affiliation(s)
- Yong-Seok Oh
- Department of Brain-Cognitive Science, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Republic of Korea
| | - Kyun Heo
- Research Institute, National Cancer Center, Goyang, Republic of Korea
| | - Eung-Kyun Kim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Jin-Hyeok Jang
- Department of Brain-Cognitive Science, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Republic of Korea
| | - Sun Sik Bae
- MRC for Ischemic Tissue Regeneration, Department of Pharmacology, School of Medicine, Pusan National University, Yangsan, Republic of Korea
| | - Jong Bae Park
- Research Institute, National Cancer Center, Goyang, Republic of Korea.,Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Republic of Korea
| | - Yun Hee Kim
- Research Institute, National Cancer Center, Goyang, Republic of Korea.,Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Republic of Korea
| | - Minseok Song
- Synaptic Circuit Plasticity Laboratory, Department of Structure and Function of Neural Network, Korea Brain Research Institute, Daegu, Republic of Korea
| | - Sang Ryong Kim
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Institute of Life Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
| | - Sung Ho Ryu
- Division of Molecular and Life Science, Department of Life Science, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - In-Hoo Kim
- Research Institute, National Cancer Center, Goyang, Republic of Korea.,Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Republic of Korea
| | - Pann-Ghill Suh
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
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Cha B, Yang J, Singh V, Zachos NC, Sarker RI, Chen TE, Chakraborty M, Tse CM, Donowitz M. PDZ domain-dependent regulation of NHE3 protein by both internal Class II and C-terminal Class I PDZ-binding motifs. J Biol Chem 2017; 292:8279-8290. [PMID: 28283572 DOI: 10.1074/jbc.m116.774489] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/06/2017] [Indexed: 12/16/2022] Open
Abstract
NHE3 directly binds Na+/H+ exchanger regulatory factor (NHERF) family scaffolding proteins that are required for many aspects of NHE3 regulation. The NHERFs bind both to an internal region (amino acids 586-660) of the NHE3 C terminus and to the NHE3 C-terminal four amino acids. The internal NHERF-binding region contains both putative Class I (-592SAV-) and Class II (-595CLDM-) PDZ-binding motifs (PBMs). Point mutagenesis showed that only the Class II motif contributes to NHERF binding. In this study, the roles in regulation of NHE3 activity of these two PBMs were investigated, revealing the following findings. 1) Interaction occurred between these binding sites because mutation of either removed nearly all NHERF binding. 2) Mutations in either significantly reduced basal NHE3 activity. Total and percent plasma membrane (PM) NHE3 protein expression was reduced in the C-terminal but not in the internal PBD mutation. 3) cGMP- and Ca2+-mediated inhibition of NHE3 was impaired in both the internal and the C-terminal PBM mutations. 4) There was a significant reduction in half-life of the PM pool of NHE3 in only the internal PBM mutation but no change in total NHE3 half-life in either. 5) There were some differences in NHE3-associating proteins in the two PBM mutations. In conclusion, NHE3 binds to NHERF proteins via both an internal Class II PBM and C-terminal Class I PBM, which interact. The former determines NHE3 stability in the PM, and the latter determines total expression and percent PM expression.
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Affiliation(s)
- Boyoung Cha
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Jianbo Yang
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Varsha Singh
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Nicholas C Zachos
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Rafiquel I Sarker
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Tian-E Chen
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Molee Chakraborty
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Chung-Ming Tse
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Mark Donowitz
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
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37
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Camilleri M, Sellin JH, Barrett KE. Pathophysiology, Evaluation, and Management of Chronic Watery Diarrhea. Gastroenterology 2017; 152:515-532.e2. [PMID: 27773805 PMCID: PMC5285476 DOI: 10.1053/j.gastro.2016.10.014] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/21/2016] [Accepted: 10/11/2016] [Indexed: 02/08/2023]
Abstract
Chronic watery diarrhea poses a diagnostic and therapeutic challenge and is often a disabling condition for patients. Although acute diarrhea is likely to be caused by infection, the causes of chronic diarrhea (>4 weeks in duration) are more elusive. We review the pathophysiology, diagnosis, and treatment of chronic diarrhea. Drawing on recent insights into the molecular mechanisms of intestinal epithelial transport and barrier function, we discuss how diarrhea can result from a decrease in luminal solute absorption, an increase in secretion, or both, as well as derangements in barrier properties. We also describe the various extraepithelial factors that activate diarrheal mechanisms. Finally, clinical evaluation and tests used in the assessment of patients presenting with chronic diarrhea are reviewed, and an algorithm guiding therapeutic decisions and pharmacotherapy is presented.
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota.
| | - Joseph H. Sellin
- Division of Gastroenterology, Department of Medicine, Baylor College of Medicine, Houston, TX
| | - Kim E. Barrett
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, La Jolla, CA
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38
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The control of male fertility by spermatid-specific factors: searching for contraceptive targets from spermatozoon's head to tail. Cell Death Dis 2016; 7:e2472. [PMID: 27831554 PMCID: PMC5260884 DOI: 10.1038/cddis.2016.344] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 09/18/2016] [Accepted: 09/26/2016] [Indexed: 02/06/2023]
Abstract
Male infertility due to abnormal spermatozoa has been reported in both animals and humans, but its pathogenic causes, including genetic abnormalities, remain largely unknown. On the other hand, contraceptive options for men are limited, and a specific, reversible and safe method of male contraception has been a long-standing quest in medicine. Some progress has recently been made in exploring the effects of spermatid-specifical genetic factors in controlling male fertility. A comprehensive search of PubMed for articles and reviews published in English before July 2016 was carried out using the search terms 'spermiogenesis failure', 'globozoospermia', 'spermatid-specific', 'acrosome', 'infertile', 'manchette', 'sperm connecting piece', 'sperm annulus', 'sperm ADAMs', 'flagellar abnormalities', 'sperm motility loss', 'sperm ion exchanger' and 'contraceptive targets'. Importantly, we have opted to focus on articles regarding spermatid-specific factors. Genetic studies to define the structure and physiology of sperm have shown that spermatozoa appear to be one of the most promising contraceptive targets. Here we summarize how these spermatid-specific factors regulate spermiogenesis and categorize them according to their localization and function from spermatid head to tail (e.g., acrosome, manchette, head-tail conjunction, annulus, principal piece of tail). In addition, we emphatically introduce small-molecule contraceptives, such as BRDT and PPP3CC/PPP3R2, which are currently being developed to target spermatogenic-specific proteins. We suggest that blocking the differentiation of haploid germ cells, which rarely affects early spermatogenic cell types and the testicular microenvironment, is a better choice than spermatogenic-specific proteins. The studies described here provide valuable information regarding the genetic and molecular defects causing male mouse infertility to improve our understanding of the importance of spermatid-specific factors in controlling fertility. Although a male contraceptive 'pill' is still many years away, research into the production of new small-molecule contraceptives targeting spermatid-specific proteins is the right avenue.
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39
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Toman O, Kabickova T, Vit O, Fiser R, Polakova KM, Zach J, Linhartova J, Vyoral D, Petrak J. Proteomic analysis of imatinib-resistant CML-T1 cells reveals calcium homeostasis as a potential therapeutic target. Oncol Rep 2016; 36:1258-68. [PMID: 27430982 PMCID: PMC4968618 DOI: 10.3892/or.2016.4945] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 03/26/2016] [Indexed: 11/16/2022] Open
Abstract
Chronic myeloid leukemia (CML) therapy has markedly improved patient prognosis after introduction of imatinib mesylate for clinical use. However, a subset of patients develops resistance to imatinib and other tyrosine kinase inhibitors (TKIs), mainly due to point mutations in the region encoding the kinase domain of the fused BCR-ABL oncogene. To identify potential therapeutic targets in imatinib-resistant CML cells, we derived imatinib-resistant CML-T1 human cell line clone (CML-T1/IR) by prolonged exposure to imatinib in growth media. Mutational analysis revealed that the Y235H mutation in BCR-ABL is probably the main cause of CML-T1/IR resistance to imatinib. To identify alternative therapeutic targets for selective elimination of imatinib-resistant cells, we compared the proteome profiles of CML-T1 and CML-T1/IR cells using 2-DE-MS. We identified eight differentially expressed proteins, with strongly upregulated Na+/H+ exchanger regulatory factor 1 (NHERF1) in the resistant cells, suggesting that this protein may influence cytosolic pH, Ca2+ concentration or signaling pathways such as Wnt in CML-T1/IR cells. We tested several compounds including drugs in clinical use that interfere with the aforementioned processes and tested their relative toxicity to CML-T1 and CML-T1/IR cells. Calcium channel blockers, calcium signaling antagonists and modulators of calcium homeostasis, namely thapsigargin, ionomycin, verapamil, carboxyamidotriazole and immunosuppressive drugs cyclosporine A and tacrolimus (FK-506) were selectively toxic to CML-T1/IR cells. The putative cellular targets of these compounds in CML-T1/IR cells are postulated in this study. We propose that Ca2+ homeostasis can be a potential therapeutic target in CML cells resistant to TKIs. We demonstrate that a proteomic approach may be used to characterize a TKI-resistant population of CML cells enabling future individualized treatment options for patients.
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Affiliation(s)
- O Toman
- Institute of Hematology and Blood Transfusion, CZ-12820 Prague 2, Czech Republic
| | - T Kabickova
- Institute of Hematology and Blood Transfusion, CZ-12820 Prague 2, Czech Republic
| | - O Vit
- BIOCEV, First Faculty of Medicine, Charles University in Prague, CZ-25250 Vestec, Czech Republic
| | - R Fiser
- Department of Genetics and Microbiology, Faculty of Natural Sciences, Charles University in Prague, CZ-12843 Prague, Czech Republic
| | - K Machova Polakova
- Institute of Hematology and Blood Transfusion, CZ-12820 Prague 2, Czech Republic
| | - J Zach
- Institute of Hematology and Blood Transfusion, CZ-12820 Prague 2, Czech Republic
| | - J Linhartova
- Institute of Hematology and Blood Transfusion, CZ-12820 Prague 2, Czech Republic
| | - D Vyoral
- Institute of Hematology and Blood Transfusion, CZ-12820 Prague 2, Czech Republic
| | - J Petrak
- Institute of Hematology and Blood Transfusion, CZ-12820 Prague 2, Czech Republic
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40
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Fellner RC, Moss NG, Goy MF. Dietary salt regulates uroguanylin expression and signaling activity in the kidney, but not in the intestine. Physiol Rep 2016; 4:4/9/e12782. [PMID: 27185905 PMCID: PMC4873633 DOI: 10.14814/phy2.12782] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 03/29/2016] [Indexed: 12/28/2022] Open
Abstract
The peptide uroguanylin (Ugn) is expressed at significant levels only in intestine and kidney, and is stored in both tissues primarily (perhaps exclusively) as intact prouroguanylin (proUgn). Intravascular infusion of either Ugn or proUgn evokes well-characterized natriuretic responses in rodents. Furthermore, Ugn knockout mice display hypertension and salt handling deficits, indicating that the Na(+) excretory mechanisms triggered when the peptides are infused into anesthetized animals are likely to operate under normal physiological conditions, and contribute to electrolyte homeostasis in conscious animals. Here, we provide strong corroborative evidence for this hypothesis, by demonstrating that UU gnV (the rate of urinary Ugn excretion) approximately doubled in conscious, unrestrained rats consuming a high-salt diet, and decreased by ~15% after salt restriction. These changes in UU gnV were not associated with altered plasma proUgn levels (shown here to be an accurate index of intestinal proUgn secretion). Furthermore, enteric Ugn mRNA levels were unaffected by salt intake, whereas renal Ugn mRNA levels increased sharply during periods of increased dietary salt consumption. Together, these data suggest that diet-evoked Ugn signals originate within the kidney, rather than the intestine, thus strengthening a growing body of evidence against a widely cited hypothesis that Ugn serves as the mediator of an entero-renal natriuretic signaling axis, while underscoring a likely intrarenal natriuretic role for the peptide. The data further suggest that intrarenal Ugn signaling is preferentially engaged when salt intake is elevated, and plays only a minor role when salt intake is restricted.
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Affiliation(s)
- Robert C Fellner
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Nicholas G Moss
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michael F Goy
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Sodium-hydrogen exchanger NHA1 and NHA2 control sperm motility and male fertility. Cell Death Dis 2016; 7:e2152. [PMID: 27010853 PMCID: PMC4823964 DOI: 10.1038/cddis.2016.65] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 02/20/2016] [Accepted: 02/25/2016] [Indexed: 12/17/2022]
Abstract
Our previous work identified NHA1, a testis-specific sodium–hydrogen exchanger, is specifically localized on the principal piece of mouse sperm flagellum. Our subsequent study suggested that the number of newborns and fertility rate of NHA1-vaccinated female mice are significantly stepped down. In order to define the physiological function of NHA1 in spermatozoa, we generated Nha1Fx/Fx, Zp3-Cre (hereafter called Nha1 cKO) mice and found that Nha1 cKO males were viable and subfertile with reduced sperm motility. Notably, cyclic AMP (cAMP) synthesis by soluble adenylyl cyclase (sAC) was attenuated in Nha1 cKO spermatozoa and cAMP analogs restored sperm motility. Similar to Nha1 cKO males, Nha2Fx/Fx, Zp3-Cre (hereafter called Nha2 cKO) male mice were subfertile, indicating these two Nha genes may be functionally redundant. Furthermore, we demonstrated that male mice lacking Nha1 and Nha2 genes (hereafter called Nha1/2 dKO mice) were completely infertile, with severely diminished sperm motility owing to attenuated sAC-cAMP signaling. Importantly, principal piece distribution of NHA1 in spermatozoa are phylogenetically conserved in spermatogenesis. Collectively, our data revealed that NHA1 and NHA2 function as a key sodium–hydrogen exchanger responsible for sperm motility after leaving the cauda epididymidis.
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Camilleri M, Bueno L, Andresen V, De Ponti F, Choi MG, Lembo A. Pharmacological, Pharmacokinetic, and Pharmacogenomic Aspects of Functional Gastrointestinal Disorders. Gastroenterology 2016; 150:S0016-5085(16)00220-1. [PMID: 27144621 DOI: 10.1053/j.gastro.2016.02.029] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 02/09/2016] [Indexed: 02/08/2023]
Abstract
This article reviews medications commonly used for the treatment of patients with functional gastrointestinal disorders. Specifically, we review the animal models that have been validated for the study of drug effects on sensation and motility; the preclinical pharmacology, pharmacokinetics, and toxicology usually required for introduction of new drugs; the biomarkers that are validated for studies of sensation and motility endpoints with experimental medications in humans; the pharmacogenomics applied to these medications and their relevance to the FGIDs; and the pharmacology of agents that are applied or have potential for the treatment of FGIDs, including psychopharmacologic drugs.
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Affiliation(s)
- Michael Camilleri
- Professor of Medicine, Pharmacology, and Physiology, Mayo Clinic College of Medicine, Consultant in Gastroenterology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Viola Andresen
- Israelitic Hospital, University of Hamburg, Orchideenstieg 14, Hamburg, Germany
| | - Fabrizio De Ponti
- Professor of Pharmacology, Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Myung-Gyu Choi
- Professor of Gastroenterology, The Catholic University of Korea College of Medicine Internal Medicine , President, Korean Society of Neurogastroenterology and Motility , Seoul, Korea
| | - Anthony Lembo
- Associate Professor, Harvard Medical School, Director of the GI Motility Laboratory at the Beth Israel Deaconess Medical Center's (BIDMC) Division of Gastroenterology, Boston, MA, USA
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Walsh DR, Nolin TD, Friedman PA. Drug Transporters and Na+/H+ Exchange Regulatory Factor PSD-95/Drosophila Discs Large/ZO-1 Proteins. Pharmacol Rev 2016; 67:656-80. [PMID: 26092975 DOI: 10.1124/pr.115.010728] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Drug transporters govern the absorption, distribution, and elimination of pharmacologically active compounds. Members of the solute carrier and ATP binding-cassette drug transporter family mediate cellular drug uptake and efflux processes, thereby coordinating the vectorial movement of drugs across epithelial barriers. To exert their physiologic and pharmacological function in polarized epithelia, drug transporters must be targeted and stabilized to appropriate regions of the cell membrane (i.e., apical versus basolateral). Despite the critical importance of drug transporter membrane targeting, the mechanisms that underlie these processes are largely unknown. Several clinically significant drug transporters possess a recognition sequence that binds to PSD-95/Drosophila discs large/ZO-1 (PDZ) proteins. PDZ proteins, such as the Na(+)/H(+) exchanger regulatory factor (NHERF) family, act to stabilize and organize membrane targeting of multiple transmembrane proteins, including many clinically relevant drug transporters. These PDZ proteins are normally abundant at apical membranes, where they tether membrane-delimited transporters. NHERF expression is particularly high at the apical membrane in polarized tissue such as intestinal, hepatic, and renal epithelia, tissues important to drug disposition. Several recent studies have highlighted NHERF proteins as determinants of drug transporter function secondary to their role in controlling membrane abundance and localization. Mounting evidence strongly suggests that NHERF proteins may have clinically significant roles in pharmacokinetics and pharmacodynamics of several pharmacologically active compounds and may affect drug action in cancer and chronic kidney disease. For these reasons, NHERF proteins represent a novel class of post-translational mediators of drug transport and novel targets for new drug development.
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Affiliation(s)
- Dustin R Walsh
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, and Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (P.A.F.); and Center for Clinical Pharmaceutical Sciences, Department of Pharmacy and Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania (D.R.W., T.D.N.)
| | - Thomas D Nolin
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, and Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (P.A.F.); and Center for Clinical Pharmaceutical Sciences, Department of Pharmacy and Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania (D.R.W., T.D.N.)
| | - Peter A Friedman
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, and Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (P.A.F.); and Center for Clinical Pharmaceutical Sciences, Department of Pharmacy and Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania (D.R.W., T.D.N.)
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Priyamvada S, Gomes R, Gill RK, Saksena S, Alrefai WA, Dudeja PK. Mechanisms Underlying Dysregulation of Electrolyte Absorption in Inflammatory Bowel Disease-Associated Diarrhea. Inflamm Bowel Dis 2015; 21:2926-35. [PMID: 26595422 PMCID: PMC4662046 DOI: 10.1097/mib.0000000000000504] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, are chronic relapsing inflammatory disorders of the gastrointestinal tract. Chronic inflammation of the intestine affects the normal fluid and electrolyte absorption leading to diarrhea, the hallmark symptom of IBD. The management of IBD-associated diarrhea still remains to be a challenge, and extensive studies over the last 2 decades have focused on investigating the molecular mechanisms underlying IBD-associated diarrhea. These studies have shown that the predominant mechanism of diarrhea in IBD involves impairment of electroneutral NaCl absorption, with very little role if any played by anion secretion. The electroneutral NaCl absorption involves coupled operation of Na/H exchanger 3 (NHE3 or SLC9A3) and Cl/HCO3 exchanger DRA (Down Regulated in Adenoma, or SLC26A3). Increasing evidence now supports the critical role of a marked decrease in NHE3 and DRA function and/or expression in IBD-associated diarrhea. This review provides a detailed analysis of the current knowledge related to alterations in NHE3 and DRA function and expression in IBD including the mechanisms underlying these observations and highlights the potential of these transporters as important and novel therapeutic targets.
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Affiliation(s)
- Shubha Priyamvada
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Rochelle Gomes
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Ravinder K. Gill
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Seema Saksena
- Jesse Brown VA Medical Center, University of Illinois at Chicago, Chicago, IL
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Waddah A. Alrefai
- Jesse Brown VA Medical Center, University of Illinois at Chicago, Chicago, IL
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Pradeep K. Dudeja
- Jesse Brown VA Medical Center, University of Illinois at Chicago, Chicago, IL
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL
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Sauvanet C, Wayt J, Pelaseyed T, Bretscher A. Structure, Regulation, and Functional Diversity of Microvilli on the Apical Domain of Epithelial Cells. Annu Rev Cell Dev Biol 2015; 31:593-621. [DOI: 10.1146/annurev-cellbio-100814-125234] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Cécile Sauvanet
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Jessica Wayt
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Thaher Pelaseyed
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
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46
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Systems biology of ion channels and transporters in tumor angiogenesis: An omics view. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2647-56. [DOI: 10.1016/j.bbamem.2014.10.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/09/2014] [Accepted: 10/20/2014] [Indexed: 01/19/2023]
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Prostacyclin receptors: Transcriptional regulation and novel signalling mechanisms. Prostaglandins Other Lipid Mediat 2015; 121:70-82. [DOI: 10.1016/j.prostaglandins.2015.04.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 03/25/2015] [Accepted: 04/18/2015] [Indexed: 12/24/2022]
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48
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Sauvanet C, Garbett D, Bretscher A. The function and dynamics of the apical scaffolding protein E3KARP are regulated by cell-cycle phosphorylation. Mol Biol Cell 2015; 26:3615-27. [PMID: 26310448 PMCID: PMC4603932 DOI: 10.1091/mbc.e15-07-0498] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 08/18/2015] [Indexed: 11/11/2022] Open
Abstract
We examine the dynamics and function of the apical scaffolding protein E3KARP/NHERF2, which consists of two PDZ domains and a tail containing an ezrin-binding domain. The exchange rate of E3KARP is greatly enhanced during mitosis due to phosphorylation at Ser-303 in its tail region. Whereas E3KARP can substitute for the function of the closely related scaffolding protein EBP50/NHERF1 in the formation of interphase microvilli, E3KARP S303D cannot. Moreover, the S303D mutation enhances the in vivo dynamics of the E3KARP tail alone, whereas in vitro the interaction of E3KARP with active ezrin is unaffected by S303D, implicating another factor regulating dynamics in vivo. A-Raf is found to be required for S303 phosphorylation in mitotic cells. Regulation of the dynamics of EBP50 is known to be dependent on its tail region but modulated by PDZ domain occupancy, which is not the case for E3KARP. Of interest, in both cases, the mechanisms regulating dynamics involve the tails, which are the most diverged region of the paralogues and probably evolved independently after a gene duplication event that occurred early in vertebrate evolution.
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Affiliation(s)
- Cécile Sauvanet
- Department of Molecular Biology and Genetics, Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, NY 14853
| | - Damien Garbett
- Department of Molecular Biology and Genetics, Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, NY 14853
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics, Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, NY 14853
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49
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Tchernychev B, Ge P, Kessler MM, Solinga RM, Wachtel D, Tobin JV, Thomas SR, Lunte CE, Fretzen A, Hannig G, Bryant AP, Kurtz CB, Currie MG, Silos-Santiago I. MRP4 Modulation of the Guanylate Cyclase-C/cGMP Pathway: Effects on Linaclotide-Induced Electrolyte Secretion and cGMP Efflux. J Pharmacol Exp Ther 2015. [PMID: 26216942 DOI: 10.1124/jpet.115.224329] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
MRP4 mediates the efflux of cGMP and cAMP and acts as an important regulator of these secondary messengers, thereby affecting signaling events mediated by cGMP and cAMP. Immunofluorescence staining showed high MRP4 expression localized predominantly in the apical membrane of rat colonic epithelium. In vitro studies were performed using a rat colonic mucosal layer mounted in an Ussing chamber. Linaclotide activation of the guanylate cyclase-C (GC-C)/cGMP pathway induced a concentration-dependent increase in transepithelial ion current [short-circuit current (Isc)] across rat colonic mucosa (EC50: 9.2 nM). Pretreatment of colonic mucosa with the specific MRP4 inhibitor MK571 potentiated linaclotide-induced electrolyte secretion and augmented linaclotide-stimulated intracellular cGMP accumulation. Notably, pretreatment with the phosphodiesterase 5 inhibitor sildenafil increased basal Isc, but had no amplifying effect on linaclotide-induced Isc. MRP4 inhibition selectively affected the activation phase, but not the deactivation phase, of linaclotide. In contrast, incubation with a GC-C/Fc chimera binding to linaclotide abrogated linaclotide-induced Isc, returning to baseline. Furthermore, linaclotide activation of GC-C induced cGMP secretion from the apical and basolateral membranes of colonic epithelium. MRP4 inhibition blocked cGMP efflux from the apical membrane, but not the basolateral membrane. These data reveal a novel, previously unrecognized mechanism that functionally couples GC-C-induced luminal electrolyte transport and cGMP secretion to spatially restricted, compartmentalized regulation by MRP4 at the apical membrane of intestinal epithelium. These findings have important implications for gastrointestinal disorders with symptoms associated with dysregulated fluid homeostasis, such as irritable bowel syndrome with constipation, chronic idiopathic constipation, and secretory diarrhea.
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Affiliation(s)
- Boris Tchernychev
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Pei Ge
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Marco M Kessler
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Robert M Solinga
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Derek Wachtel
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Jenny V Tobin
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Sara R Thomas
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Craig E Lunte
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Angelika Fretzen
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Gerhard Hannig
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Alexander P Bryant
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Caroline B Kurtz
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Mark G Currie
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Inmaculada Silos-Santiago
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
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50
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The NHERF2 sequence adjacent and upstream of the ERM-binding domain affects NHERF2-ezrin binding and dexamethasone stimulated NHE3 activity. Biochem J 2015; 470:77-90. [PMID: 26251448 PMCID: PMC4613507 DOI: 10.1042/bj20150238] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 06/16/2015] [Indexed: 12/19/2022]
Abstract
The microvillar localization of Na+-H+ exchanger regulatory factor (NHERF)1/2 requires not only ezrin, radixin and moesin (ERM)-binding domain (EBD) but also a newly defined ERM-binding regulatory sequence (EBRS) that modulates NHERF1/2–ezrin binding. NHERF2 EBRS is also regulated by phosphorylation, which affects NHE3 (Na+-H+ exchanger 3) stimulation by dexamethasone. In the brush border of intestinal and kidney epithelial cells, scaffolding proteins ezrin, Na+-H+ exchanger regulatory factor (NHERF)1 and NHERF2 play important roles in linking transmembrane proteins to the cytoskeleton and assembling signalling regulatory complexes. The last 30 carboxyl residues of NHERF1 and NHERF2 form the EBDs [ezrin, radixin and moesin (ERM)-binding domain]. The current study found that NHERF1/2 contain an ERM-binding regulatory sequence (EBRS), which facilitates the interaction between the EBD and ezrin. The EBRSs are located within 24 and 19 residues immediately upstream of EBDs for NHERF1 and NHERF2 respectively. In OK (opossum kidney) epithelial cells, EBRSs are necessary along with the EBD to distribute NHERF1 and NHERF2 exclusively to the apical domain. Furthermore, phosphorylation of Ser303 located in the EBRS of NHERF2, decreases the binding affinity for ezrin, dislocates apical NHERF2 into the cytosol and increases the NHERF2 microvillar mobility rate. Moreover, increased phosphorylation of Ser303 was functionally significant preventing acute stimulation of NHE3 (Na+-H+ exchanger 3) activity by dexamethasone.
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