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RAB3D/MDM2/β-catenin/c-MYC axis exacerbates the malignant behaviors of acute myeloid leukemia cells in vitro and in vivo. Cancer Gene Ther 2023; 30:335-344. [PMID: 36280757 DOI: 10.1038/s41417-022-00549-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 09/30/2022] [Accepted: 10/06/2022] [Indexed: 11/08/2022]
Abstract
RAB3D, a small Ras-like GTPase involved in regulating secretory pathway, plays a cancer-promoting role in several solid tumors. However, its role in leukemogenesis remains unknown yet. Acute myeloid leukemia (AML) is a common acute leukemia with a high mortality. Here, we found the higher expression of RAB3D in bone marrow mononuclear cells derived from AML patients (n = 54) versus healthy participants (n = 20). The following loss- and gain-of-function experiments demonstrated that RAB3D promoted growth, enhanced colony formation and accelerated G1/S transition of U937, THP-1 and KG-1 AML cells. RAB3D silencing inhibited tumorigenesis of AML cells in vivo and delayed AML cells-induced death of mice. Interestingly, the expression of RAB3D is positively correlated with that of an oncogene mouse double minute 2 (MDM2) in bone marrow mononuclear cells of AML patients (r = 0.923, p < 0.001). Intracellular MDM2 was conjugated with more ubiquitins and degraded faster when RAB3D was silenced. A commonly therapeutic target of AML, β-catenin signaling, was activated by RAB3D overexpression, but deactivated after MDM2 was silenced. The RAB3D-induced proliferation acceleration and β-catenin activation were abolished by MDM2 knockdown, implying that RAB3D function by stabilizing MDM2. In addition, c-MYC, a β-catenin downstream effector, was recruited directly to the RAB3D gene promoter (-360/-349 and -136/-125 sites) and induced its transcription. Collectively, this study demonstrates that RAB3D may exacerbate the malignant behaviors of AML cells through forming a positive feedback loop with MDM2/β-catenin/c-MYC signaling. RAB3D might be a novel target of clinical AML treatment.
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Casey CA, Macke AJ, Gough RR, Pachikov AN, Morris ME, Thomes PG, Kubik JL, Holzapfel MS, Petrosyan A. Alcohol-Induced Liver Injury: Down-regulation and Redistribution of Rab3D Results in Atypical Protein Trafficking. Hepatol Commun 2022; 6:374-388. [PMID: 34494400 PMCID: PMC8793998 DOI: 10.1002/hep4.1811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 08/05/2021] [Accepted: 08/05/2021] [Indexed: 12/17/2022] Open
Abstract
Previous work from our laboratories has identified multiple defects in endocytosis, protein trafficking, and secretion, along with altered Golgi function after alcohol administration. Manifestation of alcohol-associated liver disease (ALD) is associated with an aberrant function of several hepatic proteins, including asialoglycoprotein receptor (ASGP-R), their atypical distribution at the plasma membrane (PM), and secretion of their abnormally glycosylated forms into the bloodstream, but trafficking mechanism is unknown. Here we report that a small GTPase, Rab3D, known to be involved in exocytosis, secretion, and vesicle trafficking, shows ethanol (EtOH)-impaired function, which plays an important role in Golgi disorganization. We used multiple approaches and cellular/animal models of ALD, along with Rab3D knockout (KO) mice and human tissue from patients with ALD. We found that Rab3D resides primarily in trans- and cis-faces of Golgi; however, EtOH treatment results in Rab3D redistribution from trans-Golgi to cis-medial-Golgi. Cells lacking Rab3D demonstrate enlargement of Golgi, especially its distal compartments. We identified that Rab3D is required for coat protein I (COPI) vesiculation in Golgi, and conversely, COPI is critical for intra-Golgi distribution of Rab3D. Rab3D/COPI association was altered not only in the liver of patients with ALD but also in the donors consuming alcohol without steatosis. In Rab3D KO mice, hepatocytes experience endoplasmic reticulum (ER) stress, and EtOH administration activates apoptosis. Notably, in these cells, ASGP-R, despite incomplete glycosylation, can still reach cell surface through ER-PM junctions. This mimics the effects seen with EtOH-induced liver injury. Conclusion: We revealed that down-regulation of Rab3D contributes significantly to EtOH-induced Golgi disorganization, and abnormally glycosylated ASGP-R is excreted through ER-PM connections, bypassing canonical (ER→Golgi→PM) anterograde transportation. This suggests that ER-PM sites may be a therapeutic target for ALD.
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Affiliation(s)
- Carol A. Casey
- Department of Research ServiceOmaha Western Iowa Health Care System, VA ServiceOmahaNEUSA
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Amanda J. Macke
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Ryan R. Gough
- Department of Research ServiceOmaha Western Iowa Health Care System, VA ServiceOmahaNEUSA
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNEUSA
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Artem N. Pachikov
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
- The Fred and Pamela Buffett Cancer CenterOmahaNEUSA
| | - Mary E. Morris
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Paul G. Thomes
- Department of Research ServiceOmaha Western Iowa Health Care System, VA ServiceOmahaNEUSA
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Jacy L. Kubik
- Department of Research ServiceOmaha Western Iowa Health Care System, VA ServiceOmahaNEUSA
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Melissa S. Holzapfel
- Department of Pathology and MicrobiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Armen Petrosyan
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
- The Fred and Pamela Buffett Cancer CenterOmahaNEUSA
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Teng F, Hu F, Zhang M. MicroRNA-125a-5p modulates the proliferation and apoptosis of TM4 Sertoli cells by targeting RAB3D and regulating the PI3K/AKT signaling pathway. Mol Hum Reprod 2021; 27:6323363. [PMID: 34273154 DOI: 10.1093/molehr/gaab049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/06/2021] [Indexed: 12/31/2022] Open
Abstract
Sertoli cells are cells that provide protection and nutrition for developing sperm. Each stage of sperm development occurs on the surface of Sertoli cells. MicroRNA (MiR)-125a-5p is involved in male reproduction. The current research aimed to probe the role of miR-125a-5p in Sertoli cell function. Functionally, miR-125a-5p knockdown facilitated Sertoli cell proliferation, while miR-125a-5p overexpression suppressed Sertoli cell proliferation, as evidenced by 5-ethynyl-20-deoxyuridine incorporation assay. Additionally, miR-125a-5p knockdown inhibited Sertoli cell apoptosis, while miR-125a-5p upregulation facilitated Sertoli cell apoptosis, as evidenced by flow cytometry analysis. Computationally, we identified four predicted mRNA targets of miR-125a-5p. Based on the results of luciferase reporter assay, miR-125a-5p was confirmed to bind to the predicted sequence in the Ras-related protein Rab-3D (RAB3D) 3'UTR. Rescue experiments showed that miR-125a-5p suppressed the proliferative ability of TM4 Sertoli cells and facilitated their apoptosis by targeting RAB3D. Finally, our data confirmed that miR-125a-5p and RAB3D modulated activation of the PI3K/AKT pathway. In conclusion, our data showed that miR-125a-5p regulated Sertoli cell proliferation and apoptosis by targeting RAB3D and regulating the PI3K/AKT pathway.
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Affiliation(s)
- Fengmeng Teng
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinses Medicine, Nanjing 210029, Jiangsu, China
| | - Fang Hu
- Suzhou Hospital of Traditional Chinese Medicine, Suzhou 215009, Jiangsu, China
| | - Maosen Zhang
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinses Medicine, Nanjing 210029, Jiangsu, China
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A Link between Intrahepatic Cholestasis and Genetic Variations in Intracellular Trafficking Regulators. BIOLOGY 2021; 10:biology10020119. [PMID: 33557414 PMCID: PMC7914782 DOI: 10.3390/biology10020119] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/27/2021] [Accepted: 02/01/2021] [Indexed: 12/20/2022]
Abstract
Simple Summary Cholestasis refers to a medical condition in which the liver is not capable of secreting bile. The consequent accumulation of toxic bile components in the liver leads to liver failure. Cholestasis can be caused by mutations in genes that code for proteins involved in bile secretion. Recently mutations in other genes have been discovered in patients with cholestasis of unknown origin. Interestingly, many of these newly discovered genes code for proteins that regulate the intracellular distribution of other proteins, including those involved in bile secretion. This group of genes thus suggests the deregulated intracellular distribution of bile-secreting proteins as an important but still poorly understood mechanism that underlies cholestasis. To expedite a better understanding of this mechanism, we have reviewed these genes and their mutations and we discuss these in the context of cholestasis. Abstract Intrahepatic cholestasis is characterized by the accumulation of compounds in the serum that are normally secreted by hepatocytes into the bile. Genes associated with familial intrahepatic cholestasis (FIC) include ATP8B1 (FIC1), ABCB11 (FIC2), ABCB4 (FIC3), TJP2 (FIC4), NR1H4 (FIC5) and MYO5B (FIC6). With advanced genome sequencing methodologies, additional mutated genes are rapidly identified in patients presenting with idiopathic FIC. Notably, several of these genes, VPS33B, VIPAS39, SCYL1, and AP1S1, together with MYO5B, are functionally associated with recycling endosomes and/or the Golgi apparatus. These are components of a complex process that controls the sorting and trafficking of proteins, including those involved in bile secretion. These gene variants therefore suggest that defects in intracellular trafficking take a prominent place in FIC. Here we review these FIC-associated trafficking genes and their variants, their contribution to biliary transporter and canalicular protein trafficking, and, when perturbed, to cholestatic liver disease. Published variants for each of these genes have been summarized in table format, providing a convenient reference for those who work in the intrahepatic cholestasis field.
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Jin T, Liu M, Liu Y, Li Y, Xu Z, He H, Liu J, Zhang Y, Ke Y. Lcn2-derived Circular RNA (hsa_circ_0088732) Inhibits Cell Apoptosis and Promotes EMT in Glioma via the miR-661/RAB3D Axis. Front Oncol 2020; 10:170. [PMID: 32154171 PMCID: PMC7047435 DOI: 10.3389/fonc.2020.00170] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 01/31/2020] [Indexed: 12/16/2022] Open
Abstract
Background: Glioma is the most common malignant tumor of the central nervous system, and often displays invasive growth. Recently, circular RNA (circRNA), which is a novel non-coding type of RNA, has been shown to play a vital role in glioma tumorigenesis. However, the functions and mechanism of lipocalin-2 (Lcn2)-derived circular RNA (hsa_circ_0088732) in glioma progression remain unclear. Methods: We evaluated hsa_circ_0088732 expression by fluorescence in situ hybridization (FISH), Sanger sequencing, and PCR assays. Cell apoptosis was evaluated by flow cytometry and Hoechst 33258 staining. Transwell migration and invasion assays were performed to measure cell metastasis and viability. In addition, the target miRNA of hsa_circ_0088732 and the target gene of miR-661 were predicted by a bioinformatics analysis, and the interactions were verified by dual-luciferase reporter assays. RAB3D expression was analyzed by an immunochemistry assay, and E-cadherin, N-cadherin, and vimentin protein expression were examined by western blot assays. A mouse xenograft model was developed and used to analyze the effects of hsa_circ_0088732 on glioma growth in vivo. Results: We verified that hsa_circ_0088732 is circular and highly expressed in glioma tissues. Knockdown of hsa_circ_0088732 induced glioma cell apoptosis and inhibited glioma cell migration, invasion, and epithelial-mesenchymal transition (EMT). We found that hsa_circ_0088732 negatively regulated miR-661 by targeting miR-661, and RAB3D was a target gene of miR-661. In addition, inhibition of miR-661 promoted glioma cell metastasis and suppressed cell apoptosis. Knockdown of RAB3D induced cell apoptosis and suppressed cell metastasis. Moreover, hsa_circ_0088732 accelerated glioma progression through its effects on the miR-661/RAB3D axis. Finally, results from a mouse xenograft model confirmed that knockdown of hsa_circ_0088732 induced miR-661 expression, resulting in suppression of RAB3D expression and inhibition of tumor growth in vivo. Conclusion: We demonstrated that hsa_circ_0088732 facilitated glioma progression by sponging miR-661 to increase RAB3D expression. This study provides a theoretical basis for understanding the development and occurrence of glioma, as well as for the development of targeted drugs.
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Affiliation(s)
- Tao Jin
- The National Key Clinical Specialty, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, The Engineering Technology Research Center of Education Ministry of China, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Department of Neurosurgery, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou, China
| | - Mingfa Liu
- Department of Neurosurgery, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou, China
| | - Yan Liu
- Department of Neurosurgery, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou, China
| | - Yuanzhi Li
- Department of Neurosurgery, Affiliated Hengyang Hospital of Southern Medical University (Hengyang Central Hospital), Hengyang, China
| | - Zhennan Xu
- Department of Neurosurgery, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou, China
| | - Haoqi He
- The National Key Clinical Specialty, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, The Engineering Technology Research Center of Education Ministry of China, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Jie Liu
- The National Key Clinical Specialty, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, The Engineering Technology Research Center of Education Ministry of China, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Yuxuan Zhang
- The National Key Clinical Specialty, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, The Engineering Technology Research Center of Education Ministry of China, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Yiquan Ke
- The National Key Clinical Specialty, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, The Engineering Technology Research Center of Education Ministry of China, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou, China
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Jiashi W, Chuang Q, Zhenjun Z, Guangbin W, Bin L, Ming H. MicroRNA-506-3p inhibits osteosarcoma cell proliferation and metastasis by suppressing RAB3D expression. Aging (Albany NY) 2019; 10:1294-1305. [PMID: 29905536 PMCID: PMC6046236 DOI: 10.18632/aging.101468] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 06/04/2018] [Indexed: 12/20/2022]
Abstract
Osteosarcoma is an aggressive bone tumor primarily affecting children and adolescents. Its cause is not yet fully understood, and there is an urgent need for more effective treatment. In the present study we identified several miRNAs whose expression is altered in osteosarcoma compared to adjacent normal tissue. Moreover, expression levels of one of those miRNAs, miR-506-3p, correlated negatively with expression of RAB3D (a Ras-related protein). Suppression of miR-506-3p in osteosarcoma led to increased expression of RAB3D, which in turn led to increased CDK4 (cyclin-dependent kinase 4) and MMP9 (matrix metalloprotein 9) activities. Our results suggest that miR-506-3p acts as a tumor suppressor in osteosarcoma and that its downregulation leads to tumor cell proliferation and metastasis due to upregulation of RAB3D- and CDK4-mediated signaling. miR-506-3p thus appears be a potentially useful target for adjuvant therapy in osteosarcoma patients.
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Affiliation(s)
- Wang Jiashi
- Department of Orthopedic Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, People's Republic of China
| | - Qiu Chuang
- Department of Orthopedic Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, People's Republic of China
| | - Zhang Zhenjun
- Department of Orthopedic Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, People's Republic of China
| | - Wang Guangbin
- Department of Orthopedic Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, People's Republic of China
| | - Li Bin
- Department of Orthopedic Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, People's Republic of China
| | - He Ming
- Department of Orthopedic Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, People's Republic of China
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Banworth MJ, Li G. Consequences of Rab GTPase dysfunction in genetic or acquired human diseases. Small GTPases 2018. [PMID: 29239692 DOI: 10.1080/215412481397833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023] Open
Abstract
Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.
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Affiliation(s)
- Marcellus J Banworth
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Guangpu Li
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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8
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Banworth MJ, Li G. Consequences of Rab GTPase dysfunction in genetic or acquired human diseases. Small GTPases 2017; 9:158-181. [PMID: 29239692 DOI: 10.1080/21541248.2017.1397833] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.
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Affiliation(s)
- Marcellus J Banworth
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Guangpu Li
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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9
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Calmodulin interacts with Rab3D and modulates osteoclastic bone resorption. Sci Rep 2016; 6:37963. [PMID: 27897225 PMCID: PMC5126571 DOI: 10.1038/srep37963] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 11/03/2016] [Indexed: 11/09/2022] Open
Abstract
Calmodulin is a highly versatile protein that regulates intracellular calcium homeostasis and is involved in a variety of cellular functions including cardiac excitability, synaptic plasticity and signaling transduction. During osteoclastic bone resorption, calmodulin has been reported to concentrate at the ruffled border membrane of osteoclasts where it is thought to modulate bone resorption activity in response to calcium. Here we report an interaction between calmodulin and Rab3D, a small exocytic GTPase and established regulator osteoclastic bone resorption. Using yeast two-hybrid screening together with a series of protein-protein interaction studies, we show that calmodulin interacts with Rab3D in a calcium dependent manner. Consistently, expression of a calcium insensitive form of calmodulin (i.e. CaM1234) perturbs calmodulin-Rab3D interaction as monitored by bioluminescence resonance energy transfer (BRET) assays. In osteoclasts, calmodulin and Rab3D are constitutively co-expressed during RANKL-induced osteoclast differentiation, co-occupy plasma membrane fractions by differential gradient sedimentation assay and colocalise in the ruffled border as revealed by confocal microscopy. Further, functional blockade of calmodulin-Rab3D interaction by calmidazolium chloride coincides with an attenuation of osteoclastic bone resorption. Our data imply that calmodulin- Rab3D interaction is required for efficient bone resorption by osteoclasts in vitro.
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Enrich C, Rentero C, Grewal T. Annexin A6 in the liver: From the endocytic compartment to cellular physiology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:933-946. [PMID: 27984093 DOI: 10.1016/j.bbamcr.2016.10.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 12/15/2022]
Abstract
Annexin A6 (AnxA6) belongs to the conserved annexin family - a group of Ca2+-dependent membrane binding proteins. AnxA6 is the largest of all annexins and highly expressed in smooth muscle, hepatocytes, endothelial cells and cardiomyocytes. Upon activation, AnxA6 binds to negatively charged phospholipids in a wide range of intracellular localizations, in particular the plasma membrane, late endosomes/pre-lysosomes, but also synaptic vesicles and sarcolemma. In these cellular sites, AnxA6 is believed to contribute to the organization of membrane microdomains, such as cholesterol-rich lipid rafts and confer multiple regulatory functions, ranging from vesicle fusion, endocytosis and exocytosis to programmed cell death and muscle contraction. Growing evidence supports that Ca2+ and Ca2+-binding proteins control endocytosis and autophagy. Their regulatory role seems to operate at the level of the signalling pathways that initiate autophagy or at later stages, when autophagosomes fuse with endolysosomal compartments. The convergence of the autophagic and endocytic vesicles to lysosomes shares several features that depend on Ca2+ originating from lysosomes/late endosomes and seems to depend on proteins that are subsequently activated by this cation. However, the involvement of Ca2+ and its effector proteins in these autophagic and endocytic stages still remains poorly understood. Although AnxA6 makes up almost 0.25% of total protein in the liver, little is known about its function in hepatocytes. Within the endocytic route, we identified AnxA6 in endosomes and autophagosomes of hepatocytes. Hence, AnxA6 and possibly other annexins might represent new Ca2+ effectors that regulate converging steps of autophagy and endocytic trafficking in hepatocytes. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cellular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain.
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cellular, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
| | - Thomas Grewal
- Faculty of Pharmacy A15, University of Sydney, Sydney, NSW 2006, Australia
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Ishikawa T, Takizawa T, Iwaki J, Mishima T, Ui-Tei K, Takeshita T, Matsubara S, Takizawa T. Fc gamma receptor IIb participates in maternal IgG trafficking of human placental endothelial cells. Int J Mol Med 2015; 35:1273-89. [PMID: 25778799 PMCID: PMC4380207 DOI: 10.3892/ijmm.2015.2141] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/17/2015] [Indexed: 12/21/2022] Open
Abstract
The human placental transfer of maternal IgG is crucial for fetal and newborn immunity. Low-affinity immunoglobulin gamma Fc region receptor IIb2 (FCGR2B2 or FcγRIIb2) is exclusively expressed in an IgG-containing, vesicle-like organelle (the FCGR2B2 compartment) in human placental endothelial cells; thus, we hypothesized that the FCGR2B2 compartment functions as an IgG transporter. In this study, to examine this hypothesis, we performed in vitro bio-imaging analysis of IgG trafficking by FCGR2B2 compartments using human umbilical vein endothelial cells transfected with a plasmid vector containing enhanced GFP-tagged FCGR2B2 (pFCGR2B2-EGFP). FCGR2B2-EGFP signals were detected as intracellular vesicular structures similar to FCGR2B2 compartments in vivo. The internalization and transcytosis of IgG was significantly higher in the pFCGR2B2-EGFP-transfected cells than in the mock-transfected cells, and the majority of the internalized IgG was co-localized with the FCGR2B2-EGFP signals. Furthermore, we isolated FCGR2B2 compartments from the human placenta and found that the Rab family of proteins [RAS-related protein Rab family (RABs)] were associated with FCGR2B2 compartments. Among the RABs, RAB3D was expressed predominantly in placental endothelial cells. The downregulation of RAB3D by small interfering RNA (siRNA) resulted in a marked reduction in the FCGR2B2-EGFP signals at the cell periphery. Taken together, these findings suggest that FCGR2B2 compartments participate in the transcytosis of maternal IgG across the human placental endothelium and that RAB3D plays a role in regulating the intracellular dynamics of FCGR2B2 compartments.
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Affiliation(s)
- Tomoko Ishikawa
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| | - Takami Takizawa
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| | - Jun Iwaki
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| | - Takuya Mishima
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| | - Kumiko Ui-Tei
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Toshiyuki Takeshita
- Department of Obstetrics and Gynecology, Nippon Medical School, Tokyo 113-8602, Japan
| | - Shigeki Matsubara
- Department of Obstetrics and Gynecology, Jichi Medical University, Tochigi 329-0498, Japan
| | - Toshihiro Takizawa
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
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13
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Gallo LI, Liao Y, Ruiz WG, Clayton DR, Li M, Liu YJ, Jiang Y, Fukuda M, Apodaca G, Yin XM. TBC1D9B functions as a GTPase-activating protein for Rab11a in polarized MDCK cells. Mol Biol Cell 2014; 25:3779-97. [PMID: 25232007 PMCID: PMC4230784 DOI: 10.1091/mbc.e13-10-0604] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rab11a is a key modulator of vesicular trafficking processes, but there is limited information about the GEFs and GAPs that regulate its GTP-GDP cycle. TBC1D9B is identified as a Rab11a GAP in MDCK cells, where it regulates the Rab11a-dependent basolateral-to-apical transcytotic pathway. Rab11a is a key modulator of vesicular trafficking processes, but there is limited information about the guanine nucleotide-exchange factors and GTPase-activating proteins (GAPs) that regulate its GTP-GDP cycle. We observed that in the presence of Mg2+ (2.5 mM), TBC1D9B interacted via its Tre2-Bub2-Cdc16 (TBC) domain with Rab11a, Rab11b, and Rab4a in a nucleotide-dependent manner. However, only Rab11a was a substrate for TBC1D9B-stimulated GTP hydrolysis. At limiting Mg2+ concentrations (<0.5 mM), Rab8a was an additional substrate for this GAP. In polarized Madin–Darby canine kidney cells, endogenous TBC1D9B colocalized with Rab11a-positive recycling endosomes but less so with EEA1-positive early endosomes, transferrin-positive recycling endosomes, or late endosomes. Overexpression of TBC1D9B, but not an inactive mutant, decreased the rate of basolateral-to-apical IgA transcytosis—a Rab11a-dependent pathway—and shRNA-mediated depletion of TBC1D9B increased the rate of this process. In contrast, TBC1D9B had no effect on two Rab11a-independent pathways—basolateral recycling of the transferrin receptor or degradation of the epidermal growth factor receptor. Finally, expression of TBC1D9B decreased the amount of active Rab11a in the cell and concomitantly disrupted the interaction between Rab11a and its effector, Sec15A. We conclude that TBC1D9B is a Rab11a GAP that regulates basolateral-to-apical transcytosis in polarized MDCK cells.
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Affiliation(s)
- Luciana I Gallo
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Yong Liao
- Pathology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Wily G Ruiz
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Dennis R Clayton
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Min Li
- Pathology, University of Pittsburgh, Pittsburgh, PA 15261 Department of Pathology and Laboratory Medicine, Indiana University, Indianapolis, IN 46202
| | - Yong-Jian Liu
- Neurobiology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Yu Jiang
- Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Mitsunori Fukuda
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Gerard Apodaca
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261 Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Xiao-Ming Yin
- Pathology, University of Pittsburgh, Pittsburgh, PA 15261 Department of Pathology and Laboratory Medicine, Indiana University, Indianapolis, IN 46202
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14
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Abstract
Hepatocytes, like other epithelia, are situated at the interface between the organism's exterior and the underlying internal milieu and organize the vectorial exchange of macromolecules between these two spaces. To mediate this function, epithelial cells, including hepatocytes, are polarized with distinct luminal domains that are separated by tight junctions from lateral domains engaged in cell-cell adhesion and from basal domains that interact with the underlying extracellular matrix. Despite these universal principles, hepatocytes distinguish themselves from other nonstriated epithelia by their multipolar organization. Each hepatocyte participates in multiple, narrow lumina, the bile canaliculi, and has multiple basal surfaces that face the endothelial lining. Hepatocytes also differ in the mechanism of luminal protein trafficking from other epithelia studied. They lack polarized protein secretion to the luminal domain and target single-spanning and glycosylphosphatidylinositol-anchored bile canalicular membrane proteins via transcytosis from the basolateral domain. We compare this unique hepatic polarity phenotype with that of the more common columnar epithelial organization and review our current knowledge of the signaling mechanisms and the organization of polarized protein trafficking that govern the establishment and maintenance of hepatic polarity. The serine/threonine kinase LKB1, which is activated by the bile acid taurocholate and, in turn, activates adenosine monophosphate kinase-related kinases including AMPK1/2 and Par1 paralogues has emerged as a key determinant of hepatic polarity. We propose that the absence of a hepatocyte basal lamina and differences in cell-cell adhesion signaling that determine the positioning of tight junctions are two crucial determinants for the distinct hepatic and columnar polarity phenotypes.
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Affiliation(s)
- Aleksandr Treyer
- Albert Einstein College of Medicine, Department of Developmental and Molecular Biology, Bronx, New York, USA
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15
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Abstract
Bile is a unique and vital aqueous secretion of the liver that is formed by the hepatocyte and modified down stream by absorptive and secretory properties of the bile duct epithelium. Approximately 5% of bile consists of organic and inorganic solutes of considerable complexity. The bile-secretory unit consists of a canalicular network which is formed by the apical membrane of adjacent hepatocytes and sealed by tight junctions. The bile canaliculi (∼1 μm in diameter) conduct the flow of bile countercurrent to the direction of portal blood flow and connect with the canal of Hering and bile ducts which progressively increase in diameter and complexity prior to the entry of bile into the gallbladder, common bile duct, and intestine. Canalicular bile secretion is determined by both bile salt-dependent and independent transport systems which are localized at the apical membrane of the hepatocyte and largely consist of a series of adenosine triphosphate-binding cassette transport proteins that function as export pumps for bile salts and other organic solutes. These transporters create osmotic gradients within the bile canalicular lumen that provide the driving force for movement of fluid into the lumen via aquaporins. Species vary with respect to the relative amounts of bile salt-dependent and independent canalicular flow and cholangiocyte secretion which is highly regulated by hormones, second messengers, and signal transduction pathways. Most determinants of bile secretion are now characterized at the molecular level in animal models and in man. Genetic mutations serve to illuminate many of their functions.
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Affiliation(s)
- James L Boyer
- Department of Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut, USA.
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16
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Evans E, Zhang W, Jerdeva G, Chen CY, Chen X, Hamm-Alvarez SF, Okamoto CT. Direct interaction between Rab3D and the polymeric immunoglobulin receptor and trafficking through regulated secretory vesicles in lacrimal gland acinar cells. Am J Physiol Cell Physiol 2008; 294:C662-74. [PMID: 18171724 DOI: 10.1152/ajpcell.00623.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The lacrimal gland is responsible for tear production, and a major protein found in tears is secretory component (SC), the proteolytically cleaved fragment of the extracellular domain of the polymeric Ig receptor (pIgR), which is the receptor mediating the basal-to-apical transcytosis of polymeric immunoglobulins across epithelial cells. Immunofluorescent labeling of rabbit lacrimal gland acinar cells (LGACs) revealed that the small GTPase Rab3D, a regulated secretory vesicle marker, and the pIgR are colocalized in subapical membrane vesicles. In addition, the secretion of SC from primary cultures of LGACs was stimulated by the cholinergic agonist carbachol (CCH), and its release rate was very similar to that of other regulated secretory proteins in LGACs. In pull-down assays from resting LGACs, recombinant wild-type Rab3D (Rab3DWT) or the GDP-locked mutant Rab3DT36N both pulled down pIgR, but the GTP-locked mutant Rab3DQ81L did not. When the pull-down assays were performed in the presence of guanosine-5'-(gamma-thio)-triphosphate, GTP, or guanosine-5'-O-(2-thiodiphosphate), binding of Rab3DWT to pIgR was inhibited. In blot overlays, recombinant Rab3DWT bound to immunoprecipitated pIgR, suggesting that Rab3D and pIgR may interact directly. Adenovirus-mediated overexpression of mutant Rab3DT36N in LGACs inhibited CCH-stimulated SC release, and, in CCH-stimulated LGACs, pull down of pIgR with Rab3DWT and colocalization of pIgR with endogenous Rab3D were decreased relative to resting cells, suggesting that the pIgR-Rab3D interaction may be modulated by secretagogues. These data suggest that the novel localization of pIgR to the regulated secretory pathway of LGACs and its secretion therefrom may be affected by its novel interaction with Rab3D.
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Affiliation(s)
- Eunbyul Evans
- Dept. of Pharmacology and Pharmaceutical Sciences, Univ. of Southern California, Los Angeles, CA 90089-9121, USA
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17
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Pegylated Interferons: Clinical Applications in the Management of Hepatitis C Infection. HEPATITIS C VIRUS DISEASE 2008. [PMCID: PMC7122148 DOI: 10.1007/978-0-387-71376-2_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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18
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Valentijn JA, van Weeren L, Ultee A, Koster AJ. Novel localization of Rab3D in rat intestinal goblet cells and Brunner's gland acinar cells suggests a role in early Golgi trafficking. Am J Physiol Gastrointest Liver Physiol 2007; 293:G165-77. [PMID: 17395899 DOI: 10.1152/ajpgi.00520.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Rab3D is a small GTP-binding protein that associates with secretory granules of endocrine and exocrine cells. The physiological role of Rab3D remains unclear. While it has initially been implicated in the control of regulated exocytosis, recent deletion-mutation studies have suggested that Rab3D is involved in the biogenesis of secretory granules. Here, we report the unexpected finding that Rab3D also associates with early Golgi compartments in intestinal goblet cells and in Brunner's gland acinar cells. Expression of Rab3D in the intestine was demonstrated by SDS-PAGE and Western blot analysis of homogenates prepared from the rat duodenum and colon. Confocal laser scanning microscopy revealed Rab3D immunofluorescence in the Golgi area of goblet cells of the duodenum and colon and in Brunner's gland acinar cells. There was no colocalization between Rab3D and a trans-Golgi network marker, TGN-38. In contrast, Rab3D colocalized partially with a cis-Golgi marker, GM-130, and with a marker of cis-Golgi and coat protein complex I vesicles, beta-COP. Strong colocalization was observed between Rab3D and the lectins Griffonia simplicifolia agglutinin II and soybean agglutinin, which have been described as markers of the medial and cis-Golgi, respectively. Rabphilin, a putative effector of Rab3D, displayed an identical pattern of Golgi localization. Incubation of colon tissue with carbamylcholine or deoxycholate to stimulate exocytosis by goblet cells caused a partial redistribution of Rab3D to the cytoplasm and mucous granule field and a concomitant transformation of the Golgi architecture. Taken together, the present data suggest that Rab3D and rabphilin may regulate the secretory pathway at a much earlier stage than what has hitherto been assumed.
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Affiliation(s)
- Jack A Valentijn
- Electron Microscopy Division, Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
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19
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Höroldt B, Haydon G, O'Donnell K, Dudley T, Nightingale P, Mutimer D. Results of combination treatment with pegylated interferon and ribavirin in cirrhotic patients with hepatitis C infection. Liver Int 2006; 26:650-9. [PMID: 16842320 DOI: 10.1111/j.1478-3231.2006.01272.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND The treatment of hepatitis C patients with advanced cirrhotic liver disease remains challenging and data on the outcome of treatment for this patient group is limited. RESULTS Between September 2000 and August 2004, 61 cirrhotic patients started treatment with pegylated interferon and ribavirin (42 male, age range 29-69 years, 26 Asian). Forty-three (70%) patients were serum hepatitis C virus (HCV) RNA negative at the end of treatment and 24 (39%) achieved a sustained virological response (SVR). SVR was achieved for 35% (6/17) of patients with genotype 1, and for 39% (16/41) with genotype 3. Caucasians with genotype 3 demonstrated a higher cure rate (SVR 10/18 = 56%) than Asians (SVR 6/24 = 25%). Failure to achieve SVR was associated with lower platelet count, neutrophil count and albumin at baseline. Twenty patients suffered clinical or laboratory decompensation, five patients required hospitalization, and two patients died. Patients who experienced hepatic decompensation were older and had baseline characteristics associated with more advanced liver disease. CONCLUSION The treatment of patients with advanced HCV is challenging, although many treated patients achieve SVR. Significant toxicity is experienced and there is treatment-related mortality. This balance of efficacy and toxicity needs to be considered before commencing treatment.
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20
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Herrema H, Czajkowska D, Théard D, van der Wouden JM, Kalicharan D, Zolghadr B, Hoekstra D, van IJzendoorn SC. Rho kinase, myosin-II, and p42/44 MAPK control extracellular matrix-mediated apical bile canalicular lumen morphogenesis in HepG2 cells. Mol Biol Cell 2006; 17:3291-303. [PMID: 16687572 PMCID: PMC1552049 DOI: 10.1091/mbc.e06-01-0067] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 04/18/2006] [Accepted: 04/27/2006] [Indexed: 12/29/2022] Open
Abstract
The molecular mechanisms that regulate multicellular architecture and the development of extended apical bile canalicular lumens in hepatocytes are poorly understood. Here, we show that hepatic HepG2 cells cultured on glass coverslips first develop intercellular apical lumens typically formed by a pair of cells. Prolonged cell culture results in extensive organizational changes, including cell clustering, multilayering, and apical lumen morphogenesis. The latter includes the development of large acinar structures and subsequent elongated canalicular lumens that span multiple cells. These morphological changes closely resemble the early organizational pattern during development, regeneration, and neoplasia of the liver and are rapidly induced when cells are cultured on predeposited extracellular matrix (ECM). Inhibition of Rho kinase or its target myosin-II ATPase in cells cultured on glass coverslips mimics the morphogenic response to ECM. Consistently, stimulation of Rho kinase and subsequent myosin-II ATPase activity by lipoxygenase-controlled eicosatetranoic acid metabolism inhibits ECM-mediated cell multilayering and apical lumen morphogenesis but not initial apical lumen formation. Furthermore, apical lumen remodeling but not cell multilayering requires basal p42/44 MAPK activity. Together, the data suggest a role for hepatocyte-derived ECM in the spatial organization of hepatocytes and apical lumen morphogenesis and identify Rho kinase, myosin-II, and MAPK as potentially important players in different aspects of bile canalicular lumen morphogenesis.
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Affiliation(s)
| | | | | | | | - Dharamdajal Kalicharan
- Electron Microscopy, Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 AV Groningen, The Netherlands
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21
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Marcus EL, Tur-Kaspa R. Chronic hepatitis C virus infection in older adults. Clin Infect Dis 2005; 41:1606-12. [PMID: 16267733 DOI: 10.1086/497597] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Accepted: 07/20/2005] [Indexed: 02/05/2023] Open
Abstract
Most of the older adults with chronic hepatitis C virus infection acquired the disease earlier in life. These patients often present with complications of liver disease, mainly cirrhosis and hepatocellular carcinoma. The burden of chronic hepatitis C virus infection in elderly persons is expected to increase significantly in the United States during the next 2 decades. It seems important that, for elderly patients with chronic hepatitis C, the risk-benefit of combination antiviral therapy consisting of pegylated interferon and ribavirin should be assessed on an individual basis. Assessment should be performed in all cases before considering treatment, and it should include evaluation of the degree of liver fibrosis by means of liver biopsy or, possibly, by means of noninvasive methods. Novel antiviral drugs that may have fewer adverse effects, such as protease inhibitors, may serve as potential alternatives. It is recommended that elderly patients (up to the age of 75 years) be included in randomized trials of chronic hepatitis C virus infection treatment.
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Affiliation(s)
- Esther-Lee Marcus
- Acute Geriatric Department, Herzog Hospital, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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22
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Sulkowski M, Wright T, Rossi S, Arora S, Lamb M, Wang K, Gries JM, Yalamanchili S. Peginterferon alfa-2a does not alter the pharmacokinetics of methadone in patients with chronic hepatitis C undergoing methadone maintenance therapy. Clin Pharmacol Ther 2005; 77:214-24. [PMID: 15735615 DOI: 10.1016/j.clpt.2004.09.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Our objective was to quantify the pharmacokinetics of methadone and the pharmacokinetics and pharmacodynamics of peginterferon alfa-2a (40 kd) in patients with chronic hepatitis C undergoing methadone maintenance therapy. METHODS Adults with chronic hepatitis C who had been receiving a consistent methadone maintenance regimen for at least 3 months were eligible for this open-label, multicenter, nonrandomized drug interaction study. All patients received 180 microg subcutaneous peginterferon alfa-2a once weekly for 4 weeks and continued their methadone regimen. Serial blood samples were collected at baseline and immediately before and for up to 168 hours after study drug administration for the purposes of quantifying methadone and peginterferon alfa-2a serum concentrations, measuring serum 2',5'-oligoadenylate synthetase activity, and determining hepatitis C virus ribonucleic acid levels. RESULTS Twenty-four patients were enrolled. Methadone exposure, as measured by maximum serum concentration (C(max)) and area under the concentration-time curve (AUC) normalized to a 100-mg/d dose, after 4 doses of peginterferon alfa-2a increased by 10% to 15% when compared with baseline. The week 4/baseline ratio of the mean C(max) was 1.11 (90% confidence interval [CI], 1.02-1.22), and for AUC from time 0 to 24 hours, the week 4/baseline ratio was 1.15 (90% CI, 1.08-1.23). The mean accumulation ratios (week 4/first dose) for C(max) and AUC from time 0 to 168 hours of peginterferon alfa-2a were 2.1 and 2.3, respectively. CONCLUSIONS Peginterferon alfa-2a does not appreciably alter the pharmacokinetics of methadone.
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Affiliation(s)
- Mark Sulkowski
- Viral Hepatitis Center, Johns Hopkins Medical Institutions, 1830 E Monument St, Room 448, Baltimore, MD 21205, USA.
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23
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Hoekstra D, Tyteca D, van IJzendoorn SCD. The subapical compartment: a traffic center in membrane polarity development. J Cell Sci 2005; 117:2183-92. [PMID: 15126620 DOI: 10.1242/jcs.01217] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Spatially separated apical and basolateral plasma membrane domains that have distinct functions and molecular compositions are a characteristic feature of epithelial cell polarity. The subapical compartment (SAC), also known as the common endosome (CE), where endocytic pathways from both surfaces merge, plays a crucial role in the maintenance and probably the biogenesis of these distinct membrane domains. Although differences in morphology are apparent, the same principal features of a SAC can be distinguished in different types of epithelial cells. As polarity develops, the compartment acquires several distinct machineries that, in conjunction with the cytoskeleton, are necessary for polarized trafficking. Disrupting trafficking via the SAC and hence bypassing its sorting machinery, as occurs upon actin depolymerization, leads to mis-sorting of apical and basolateral molecules, thereby compromising the development of polarity. The structural and functional integrity of the compartment in part depends on microtubules. Moreover, the acquisition of a particular set of Rab proteins, including Rab11 and Rab3, appears to be crucial in regulating molecular sorting and vesicular transport relevant both to recycling to either plasma membrane domain and to de novo assembly of the apical domain. Furthermore, subcompartmentalization of the SAC appears to be key to its various functions.
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Affiliation(s)
- Dick Hoekstra
- Department of Membrane Cell Biology, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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24
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25
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Johnson CL, Kowalik AS, Rajakumar N, Pin CL. Mist1 is necessary for the establishment of granule organization in serous exocrine cells of the gastrointestinal tract. Mech Dev 2004; 121:261-72. [PMID: 15003629 DOI: 10.1016/j.mod.2004.01.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Revised: 01/07/2004] [Accepted: 01/11/2004] [Indexed: 12/17/2022]
Abstract
Establishing a pool of granules at the luminal border is a key step during exocrine cell development in the pancreas and is necessary for efficient release of digestive enzymes through regulated exocytosis. Several proteins have been linked to maintaining granule organization, but it is unclear which regulatory mechanisms are necessary to establish organization. Based on temporal and spatial expression, the transcription factor Mist1 is an excellent candidate, and analysis of mice that do not express Mist1 (Mist1KO) reveal disrupted cell morphology in adult pancreatic acini. To address Mist1's role in establishing granule location, we have characterized the organization of pancreatic acini throughout development in Mist1KO mice. Using various histological approaches, we have determined that correct granule organization is never established in pancreatic acini of Mist1KO mice. Further examination indicates that this disruption in granule targeting may be the primary defect in Mist1KO mice as granule organization is affected in other serous exocrine cells that normally express Mist1. To identify a mechanistic link between granule targeting and the loss of Mist1 function, intercellular junctions and the expression of Rab3D were assessed. While both of these factors are affected in Mist1KO mice, these changes alone do not account for the disorganization observed in Mist1KO tissues. Therefore, we conclude that Mist1 is necessary for complete differentiation and maturation of serous exocrine cells through the combined regulation of several exocrine specific genes.
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Affiliation(s)
- Charis L Johnson
- Department of Physiology and Pharmacology, University of Western Ontario, Child Health Research Institute, London, Ont., Canada N6C 2V5
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26
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Larkin JM, Coleman H, Espinosa A, Levenson A, Park MS, Woo B, Zervoudakis A, Tinh V. Intracellular accumulation of pIgA-R and regulators of transcytotic trafficking in cholestatic rat hepatocytes. Hepatology 2003; 38:1199-209. [PMID: 14578858 DOI: 10.1053/jhep.2003.50419] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Bile duct ligation (BDL) impairs basolateral-to-apical transcytosis in hepatocytes, causing accumulation of transcytotic carriers for the polymeric IgA receptor (pIgA-R) and redistribution of secretory component (SC) from bile to blood. To gain insight into the mechanisms regulating transcytosis and the pathophysiology of cholestasis, we investigated nascent protein trafficking in control and BDL livers using cell fractionation in the context of in vivo pulse-chase experiments and immunoblot analysis. Control and cholestatic hepatocytes trafficked [35S]-labeled serum proteins and the pIgA-R along the secretory pathway with identical kinetics. However, BDL impaired transcytosis, causing (1) accumulation of the pIgA-R, rab3D, rab11a, and other candidate regulators of apical-directed secretion in a crude vesicle carrier fraction (CVCF) enriched in transcytotic carriers; (2) slow delivery of [35S]-labeled SC to bile; and (3) paracellular reflux of SC from bile to blood. In conclusion, these data indicate that the secretory and transcytotic pathways remain polarized in cholestatic hepatocytes and suggest that the pIgA-R traffics through postendosomal rab3D-, rab11a-, and syntaxin 2-associated compartments, implicating these proteins in the regulation of transcytosis.
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Affiliation(s)
- Janet M Larkin
- Department of Biological Sciences, Barnard College, New York, NY 10027, USA.
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27
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Hadziyannis SJ, Papatheodoridis GV. Peginterferon-alpha2a (40 kDa) for chronic hepatitis C. Expert Opin Pharmacother 2003; 4:541-51. [PMID: 12667117 DOI: 10.1517/14656566.4.4.541] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Pegylated IFN-alpha(2a) (PEG-IFN-alpha(2a) [40 kDa]; Pegasys, Hoffmann-La Roche) is a new subcutaneous formulation of IFN-alpha(2a), produced by its attachment to a 40 kDa branched polyethylene glycol moiety by a stable amide bond. PEG-IFN-alpha(2a) 180 micro g once-weekly has enhanced pharmacokinetic and pharmacodynamic properties which translate into significantly improved efficacy and similar safety and tolerability compared with IFN-alpha in patients with chronic hepatitis C even with underlying cirrhosis. The combination of PEG-IFN-alpha(2a) (40 kDa) plus ribavirin produces significantly better sustained virological responses than the combination of IFN-alpha(2b) and ribavirin, while it is accompanied by a similar or even lower incidence of adverse events and better quality of life. PEG-IFN-alpha(2a) (40 kDa) is the first pegylated IFN-alpha for which evidence-based recommendations can be made on optimum therapy duration and ribavirin dose according to HCV genotype. PEG-IFN-alpha(2a) (40 kDa) is expected to improve the efficacy and tolerability of treatment for chronic hepatitis C.
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Affiliation(s)
- Stephanos J Hadziyannis
- Department of Medicine & Hepatology, Henry Dunant Hospital, 107 Messogion Ave, 11526 Athens, Greece.
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28
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van Ijzendoorn SCD, Mostov KE, Hoekstra D. Role of Rab Proteins in Epithelial Membrane Traffic. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 232:59-88. [PMID: 14711116 DOI: 10.1016/s0074-7696(03)32002-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Small GTPase rab proteins play an important role in various aspects of membrane traffic, including cargo selection, vesicle budding, vesicle motility, tethering, docking, and fusion. Recent data suggest also that rabs, and their divalent effector proteins, organize organelle subdomains and as such may define functional organelle identity. Most rabs are ubiquitously expressed. However, some rabs are preferentially expressed in epithelial cells where they appear intimately associated with the epithelial-specific transcytotic pathway and/or tight junctions. This review discusses the role of rabs in epithelial membrane transport.
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Affiliation(s)
- Sven C D van Ijzendoorn
- Department of Membrane Cell Biology, University of Groningen, Groningen 9713AV, The Netherlands
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29
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Tuma PL, Nyasae LK, Hubbard AL. Nonpolarized cells selectively sort apical proteins from cell surface to a novel compartment, but lack apical retention mechanisms. Mol Biol Cell 2002; 13:3400-15. [PMID: 12388745 PMCID: PMC129954 DOI: 10.1091/mbc.02-04-0054] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2002] [Revised: 06/18/2002] [Accepted: 07/22/2002] [Indexed: 01/21/2023] Open
Abstract
Membrane trafficking is central to establishing and maintaining epithelial cell polarity. One open question is to what extent the mechanisms regulating membrane trafficking are conserved between nonpolarized and polarized cells. To answer this question, we examined the dynamics of domain-specific plasma membrane (PM) proteins in three classes of hepatic cells: polarized and differentiated WIF-B cells, nonpolarized and differentiated Fao cells, and nonpolarized and nondifferentiated Clone 9 cells. In nonpolarized cells, mature apical proteins were uniformly distributed in the PM. Surprisingly, they were also in an intracellular compartment. Double labeling revealed that the compartment contained only apical proteins. By monitoring the dynamics of antibody-labeled molecules in nonpolarized cells, we further found that apical proteins rapidly recycled between the compartment and PM. In contrast, the apical PM residents in polarized cells showed neither internalization nor return to the basolateral PM from which they had originally come. Cytochalasin D treatment of these polarized cells revealed that the retention mechanisms are actin dependent. We conclude from these data that both polarized and nonpolarized cells selectively sort apical proteins from the PM and transport them to specific, but different cellular locations. We propose that the intracellular recycling compartment in nonpolarized cells is an intermediate in apical surface formation.
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Affiliation(s)
- Pamela L Tuma
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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van IJzendoorn SCD, Tuvim MJ, Weimbs T, Dickey BF, Mostov KE. Direct interaction between Rab3b and the polymeric immunoglobulin receptor controls ligand-stimulated transcytosis in epithelial cells. Dev Cell 2002; 2:219-28. [PMID: 11832247 DOI: 10.1016/s1534-5807(02)00115-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have examined the role of rab3b in epithelial cells. In MDCK cells, rab3b localizes to vesicular structures containing the polymeric immunoglobulin receptor (pIgR) and located subjacent to the apical surface. We found that GTP-bound rab3b directly interacts with the cytoplasmic domain of pIgR. Binding of dIgA to pIgR causes a dissociation of the interaction with rab3b, a process that requires dIgA-mediated signaling, Arg657 in the cytoplasmic domain of pIgR, and possibly GTP hydrolysis by rab3b. Binding of dIgA to pIgR at the basolateral surface stimulates subsequent transcytosis to the apical surface. Overexpression of GTP-locked rab3b inhibits dIgA-stimulated transcytosis. Together, our data demonstrate that a rab protein can bind directly to a specific cargo protein and thereby control its trafficking.
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Affiliation(s)
- Sven C D van IJzendoorn
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA
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Qiu X, Valentijn JA, Jamieson JD. Carboxyl-methylation of Rab3D in the rat pancreatic acinar tumor cell line AR42J. Biochem Biophys Res Commun 2001; 285:708-14. [PMID: 11453651 DOI: 10.1006/bbrc.2001.5224] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rab3D is a small GTPase implicated in regulated exocytosis, and is a marker of secretory granules in exocrine cells. We have previously shown that rab3D undergoes reversible carboxyl-methylation in adult rat pancreatic acinar cells, and that carboxyl-methylation of rab3D is developmentally regulated concomitantly with the maturation of the regulated secretory apparatus in rat pancreas. We also observed that dexamethasone treatment of the rat pancreatic acinar tumor cell line, AR42J, led to a significant increase in the size of the unmethylated pool of a rab3-like protein. The current study was designed to further characterize this rab3-like protein. Here we show that AR42J cells express rab3D, and that the protein focuses on 2D gels as two spots with pI values of 4.9 and 5.0. Treatment of AR42J cells with N-acetyl-S-geranylgeranyl-l-cysteine, an inhibitor of carboxyl-methylation, led to a decrease in the basic form of rab3D and a proportional increase in the acidic form. In contrast, N-acetyl-S-farnesyl-l-cysteine, which inhibits carboxyl-methylation of farnesylated proteins, had no effect. Lovastatin, an inhibitor of geranylgeranylation, also induced an accumulation of the acidic form of rab3D. Taken together, these data indicate that rab3D can undergo reversible carboxyl-methylation in AR42J cells by a geranylgeranyl-specific methyltransferase. The 2D gel and immunoblotting analyses indicated that dexamethasone treatment of AR42J cells led to an increase in the proportion of the unmethylated form of rab3D concurrent to inducing a regulated secretory pathway, similar to the rab3D profile change in developing rat pancreas. Our data, along with previous studies done on developing rat pancreas, indicate that the tumor cell line AR42J represents a good model system for studying the regulated secretory pathway, and that carboxyl-methylation of rab3D may play a role in the acquisition of stimulus-secretion coupling.
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Affiliation(s)
- X Qiu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
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Shiffman ML. Pegylated interferons: what role will they play in the treatment of chronic hepatitis C? Curr Gastroenterol Rep 2001; 3:30-7. [PMID: 11177692 DOI: 10.1007/s11894-001-0038-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
The primary therapy for patients with chronic hepatitis C virus (HCV) infection is interferon alfa. However, use of interferon for treatment of chronic HCV has several shortcomings that limit its effectiveness. Interferon has a very short half-life, must be administered multiple times weekly, and is associated with significant side effects. "PEGylation" is a process whereby the inert polymer, polyethylene glycol (PEG), is attached to a protein pharmaceutical. This process has been shown to alter the properties of PEGylated proteins in a manner that significantly extends half-life, reduces immunogenicity, and enhances biologic activity when compared with the native protein. In recent years, several PEGylated forms of interferon alfa have been developed. Recent studies have demonstrated that PEG-interferons have a significantly prolonged half-life and sustained virologic response when compared with standard interferon. Studies to evaluate the effects of combining PEG-interferons with ribavirin are currently underway. The role PEG-interferons will play in patients who have either relapsed or failed to respond to previous interferon or interferon/ribavirin therapy remains to be defined.
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Affiliation(s)
- M L Shiffman
- Hepatology Section, Medical College of Virginia Commonwealth University, Box 980341, Richmond, VA 23298, USA.
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