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Heydecker M, Shitara A, Chen D, Tran DT, Masedunskas A, Tora MS, Ebrahim S, Appaduray MA, Galeano Niño JL, Bhardwaj A, Narayan K, Hardeman EC, Gunning PW, Weigert R. Coordination of force-generating actin-based modules stabilizes and remodels membranes in vivo. J Cell Biol 2024; 223:e202401091. [PMID: 39172125 DOI: 10.1083/jcb.202401091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 06/18/2024] [Accepted: 08/07/2024] [Indexed: 08/23/2024] Open
Abstract
Membrane remodeling drives a broad spectrum of cellular functions, and it is regulated through mechanical forces exerted on the membrane by cytoplasmic complexes. Here, we investigate how actin filaments dynamically tune their structure to control the active transfer of membranes between cellular compartments with distinct compositions and biophysical properties. Using intravital subcellular microscopy in live rodents we show that a lattice composed of linear filaments stabilizes the granule membrane after fusion with the plasma membrane and a network of branched filaments linked to the membranes by Ezrin, a regulator of membrane tension, initiates and drives to completion the integration step. Our results highlight how the actin cytoskeleton tunes its structure to adapt to dynamic changes in the biophysical properties of membranes.
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Affiliation(s)
- Marco Heydecker
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Akiko Shitara
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Department of Pharmacology, Asahi University School of Dentistry, Gifu, Japan
| | - Desu Chen
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Duy T Tran
- NIDCR Imaging Core, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Andrius Masedunskas
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Muhibullah S Tora
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Seham Ebrahim
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Department of Molecular Physiology and Biological Physics, Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Mark A Appaduray
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Jorge Luis Galeano Niño
- EMBL Australia, Single Molecule Science node, University of New South Wales Sydney, Sydney, Australia
| | - Abhishek Bhardwaj
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Kedar Narayan
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Edna C Hardeman
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Peter W Gunning
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Roberto Weigert
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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Heydecker M, Shitara A, Chen D, Tran D, Masedunskas A, Tora M, Ebrahim S, Appaduray MA, Galeano Niño JL, Bhardwaj A, Narayan K, Hardeman EC, Gunning PW, Weigert R. Spatial and Temporal Coordination of Force-generating Actin-based Modules Drives Membrane Remodeling In Vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.04.569944. [PMID: 38168275 PMCID: PMC10760165 DOI: 10.1101/2023.12.04.569944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Membrane remodeling drives a broad spectrum of cellular functions, and it is regulated through mechanical forces exerted on the membrane by cytoplasmic complexes. Here, we investigate how actin filaments dynamically tune their structure to control the active transfer of membranes between cellular compartments with distinct compositions and biophysical properties. Using intravital subcellular microscopy in live rodents we show that: a lattice composed of linear filaments stabilizes the granule membrane after fusion with the plasma membrane; and a network of branched filaments linked to the membranes by Ezrin, a regulator of membrane tension, initiates and drives to completion the integration step. Our results highlight how the actin cytoskeleton tunes its structure to adapt to dynamic changes in the biophysical properties of membranes.
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Kawase A, Hirosoko M, Sugihara Y, Koyama Y, Fukae A, Shimada H, Iwaki M. NHERF1/EBP50 as a Target for Modulation of MRP Function in HepG2 Cells. Pharmaceuticals (Basel) 2021; 14:ph14030239. [PMID: 33800412 PMCID: PMC8002045 DOI: 10.3390/ph14030239] [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: 01/19/2021] [Revised: 02/16/2021] [Accepted: 03/05/2021] [Indexed: 12/12/2022] Open
Abstract
As increased expression and activities of efflux transporters (ETs) often cause drug resistance in cancers, we tried modulating ET activity in cancer cells, using scaffold proteins such as ezrin/radixin/moesin (ERM) proteins, and Na+/H+ exchanger regulatory factor-1 (NHERF1)/ERM-binding phosphoprotein of 50 kDa (EBP50). To see whether EBP50 modulated ET activities in human liver cancer HepG2 cells, we used EBP50 siRNA and a designed TAT-PDZ1 peptide. The EBP50 knockdown (EBP50KD) cells had significantly higher intracellular accumulations of Rho123 and carboxy-dichlorofluorescein (CDF), but not H33342 (i.e., the respective substrates of P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), and breast cancer resistance protein (BCRP)), compared with control HepG2, suggesting that EBP50 knockdown in HepG2 cells decreased activity of P-gp and MRP but not BCRP. Treatment with TAT-PDZ1 peptide (>1 pM) resulted in significantly higher CDF accumulation in HepG2 cells, which persisted for ≥180 min after TAT-PDZ1 peptide treatment. These results imply that EBP50 can modulate ET activities. To our knowledge, this is the first report on using a competitive peptide to modulate interactions between MRP and EBP50.
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Affiliation(s)
- Atsushi Kawase
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, Osaka 577-8502, Japan; (M.H.); (Y.S.); (Y.K.); (A.F.); (H.S.); (M.I.)
- Correspondence:
| | - Miho Hirosoko
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, Osaka 577-8502, Japan; (M.H.); (Y.S.); (Y.K.); (A.F.); (H.S.); (M.I.)
| | - Yuka Sugihara
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, Osaka 577-8502, Japan; (M.H.); (Y.S.); (Y.K.); (A.F.); (H.S.); (M.I.)
| | - Yunosuke Koyama
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, Osaka 577-8502, Japan; (M.H.); (Y.S.); (Y.K.); (A.F.); (H.S.); (M.I.)
| | - Ayaka Fukae
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, Osaka 577-8502, Japan; (M.H.); (Y.S.); (Y.K.); (A.F.); (H.S.); (M.I.)
| | - Hiroaki Shimada
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, Osaka 577-8502, Japan; (M.H.); (Y.S.); (Y.K.); (A.F.); (H.S.); (M.I.)
| | - Masahiro Iwaki
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, Osaka 577-8502, Japan; (M.H.); (Y.S.); (Y.K.); (A.F.); (H.S.); (M.I.)
- Pharmaceutical Research and Technology Institute, Kindai University, Osaka 577-8502, Japan
- Antiaging Center, Kindai University, Osaka 577-8502, Japan
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Ogihara T, Mizoi K, Kamioka H, Yano K. Physiological Roles of ERM Proteins and Transcriptional Regulators in Supporting Membrane Expression of Efflux Transporters as Factors of Drug Resistance in Cancer. Cancers (Basel) 2020; 12:E3352. [PMID: 33198344 PMCID: PMC7696277 DOI: 10.3390/cancers12113352] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 12/23/2022] Open
Abstract
One factor contributing to the malignancy of cancer cells is the acquisition of drug resistance during chemotherapy via increased expression of efflux transporters, such as P-glycoprotein (P-gp), multidrug resistance-associated proteins (MRPs), and breast cancer resistance protein (BCRP). These transporters operate at the cell membrane, and are anchored in place by the scaffold proteins ezrin (Ezr), radixin (Rdx), and moesin (Msn) (ERM proteins), which regulate their functional activity. The identity of the regulatory scaffold protein(s) differs depending upon the transporter, and also upon the tissue in which it is expressed, even for the same transporter. Another factor contributing to malignancy is metastatic ability. Epithelial-mesenchymal transition (EMT) is the first step in the conversion of primary epithelial cells into mesenchymal cells that can be transported to other organs via the blood. The SNAI family of transcriptional regulators triggers EMT, and SNAI expression is used is an indicator of malignancy. Furthermore, EMT has been suggested to be involved in drug resistance, since drug excretion from cancer cells is promoted during EMT. We showed recently that ERM proteins are induced by a member of the SNAI family, Snail. Here, we first review recent progress in research on the relationship between efflux transporters and scaffold proteins, including the question of tissue specificity. In the second part, we review the relationship between ERM scaffold proteins and the transcriptional regulatory factors that induce their expression.
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Affiliation(s)
- Takuo Ogihara
- Graduate School of Pharmaceutical Sciences, Takasaki University of Health and Welfare, 60, Nakaorui-machi, Takasaki, Gunma 370-0033, Japan;
| | - Kenta Mizoi
- Faculty of Pharmacy, Takasaki University of Health and Welfare, 60, Nakaorui-machi, Takasaki, Gunma 370-0033, Japan; (K.M.); (K.Y.)
| | - Hiroki Kamioka
- Graduate School of Pharmaceutical Sciences, Takasaki University of Health and Welfare, 60, Nakaorui-machi, Takasaki, Gunma 370-0033, Japan;
| | - Kentaro Yano
- Faculty of Pharmacy, Takasaki University of Health and Welfare, 60, Nakaorui-machi, Takasaki, Gunma 370-0033, Japan; (K.M.); (K.Y.)
- Laboratory of Drug Metabolism and Pharmacokinetics, Yokohama University of Pharmacy, 601, Matano-cho, Totsuka-ku, Yokohama, Kanagawa 245-0066, Japan
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Karvar S, Ansa-Addo EA, Suda J, Singh S, Zhu L, Li Z, Rockey DC. Moesin, an Ezrin/Radixin/Moesin Family Member, Regulates Hepatic Fibrosis. Hepatology 2020; 72:1073-1084. [PMID: 31860744 PMCID: PMC7437180 DOI: 10.1002/hep.31078] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 12/06/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS Moesin, an ezrin/radixin/moesin family member, is involved in the regulation of cell adhesion, polarity, and migration by cross-linking between the actin cytoskeleton and plasma membrane. The primary effector cell in hepatic fibrosis is the hepatic stellate cell (HSC), which undergoes activation during liver injury leading to increased extracellular matrix production. APPROACH AND RESULTS Here, we have hypothesized that moesin plays a critical role in linking the HSC cytoskeleton to the fibrogenic cascade during HSC activation. Moesin phosphorylation was up-regulated during HSC activation and fibrogenesis. Using moesin wild-type (WT) and mutant constructs (phosphomimicking T558D and nonphosphorylatable T558A), we found that cellular motility and contraction were increased in moesin WT-infected and T558D-infected cells, paralleled by an increase in smooth muscle α-actin and collagen 1 expression. In contrast, overexpression of nonphosphorylatable moesin and moesin knockout (KO) decreased cellular motility and contraction. Most importantly, moesin KO led to abrogation of liver fibrosis. The mechanism of moesin's effect was a reduction in myocardin-related transcription factor-A and serum-response factor (SRF)-mediated changes in the actin cytoskeleton, which in turn modulated the expression of matrix genes. CONCLUSIONS Taken together, our findings suggest that the linkage between cytoskeletal dynamics and the correlated MRTF/SRF signaling pathway has a pivotal role in HSC activation and fibrogenesis.
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Affiliation(s)
- Serhan Karvar
- Division of Gastroenterology and Hepatology, Department of
Medicine, Medical University of South Carolina, Charleston, SC, USA
| | | | - Jo Suda
- Department of Biomedical Sciences, Cedars-Sinai Medical
Center, Los Angeles, CA
| | | | - Lixin Zhu
- Guangdong Institute of Gastroenterology, Guangdong
Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of
Colorectal Surgery, the Sixth Affiliated Hospital, Sun Yat-sen University,
Guangzhou, China. Department of Biochemistry and Department of Pediatrics,
University at Buffalo, Buffalo, NY
| | - Zihai Li
- Department of Microbiology and Immunology, Hollings Cancer
Center
| | - Don C. Rockey
- Division of Gastroenterology and Hepatology, Department of
Medicine, Medical University of South Carolina, Charleston, SC, USA
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Reduced Mrp2 surface availability as PI3Kγ-mediated hepatocytic dysfunction reflecting a hallmark of cholestasis in sepsis. Sci Rep 2020; 10:13110. [PMID: 32753644 PMCID: PMC7403153 DOI: 10.1038/s41598-020-69901-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 06/30/2020] [Indexed: 12/14/2022] Open
Abstract
Sepsis-associated liver dysfunction manifesting as cholestasis is common during multiple organ failure. Three hepatocytic dysfunctions are considered as major hallmarks of cholestasis in sepsis: impairments of microvilli covering canalicular membranes, disruptions of tight junctions sealing bile-collecting canaliculae and disruptions of Mrp2-mediated hepatobiliary transport. PI3Kγ loss-of-function was suggested as beneficial in early sepsis. Yet, the PI3Kγ-regulated cellular processes in hepatocytes remained largely unclear. We analysed all three sepsis hallmarks for responsiveness to massive PI3K/Akt signalling and PI3Kγ loss-of-function, respectively. Surprisingly, neither microvilli nor tight junctions were strongly modulated, as shown by electron microscopical studies of mouse liver samples. Instead, quantitative electron microscopy proved that solely Mrp2 surface availability, i.e. the third hallmark, responded strongly to PI3K/Akt signalling. Mrp2 plasma membrane levels were massively reduced upon PI3K/Akt signalling. Importantly, Mrp2 levels at the plasma membrane of PI3Kγ KO hepatocytes remained unaffected upon PI3K/Akt signalling stimulation. The effect explicitly relied on PI3Kγ's enzymatic ability, as shown by PI3Kγ kinase-dead mice. Keeping the surface availability of the biliary transporter Mrp2 therefore is a cell biological process that may underlie the observation that PI3Kγ loss-of-function protects from hepatic excretory dysfunction during early sepsis and Mrp2 should thus take center stage in pharmacological interventions.
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Thompson KJ, Wessling-Resnick M. ZIP14 is degraded in response to manganese exposure. Biometals 2019; 32:829-843. [PMID: 31541377 PMCID: PMC7755095 DOI: 10.1007/s10534-019-00216-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 09/10/2019] [Indexed: 12/16/2022]
Abstract
Manganese (Mn) is an essential element necessary for proper development and brain function. Circulating Mn levels are regulated by hepatobiliary clearance to limit toxic levels and prevent tissue deposition. To characterize mechanisms involved in hepatocyte Mn uptake, polarized human HepaRG cells were used for this study. Western blot analysis and immunofluorescence microscopy showed the Mn transporter ZIP14 was expressed and localized to the basolateral surface of polarized HepaRG cells. HepaRG cells took up 54Mn in a time- and temperature-dependent manner but uptake was reduced after exposure to Mn. This loss in transport activity was associated with decreased ZIP14 protein levels in response to Mn exposure. Mn-induced degradation of ZIP14 was blocked by bafilomycin A1, which increased localization of the transporter in Lamp1-positive vesicles. Mn exposure also down-regulated the Golgi proteins TMEM165 and GPP130 while the ER stress marker BiP was induced. These results indicate that Mn exposure decreases ZIP14 protein levels to limit subsequent uptake of Mn as a cytoprotective response. Thus, high levels of Mn may compromise first-pass-hepatic clearance mechanisms.
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Affiliation(s)
- Khristy J Thompson
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, 665 Huntington Avenue, Boston, MA, 02115, USA.
| | - Marianne Wessling-Resnick
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, 665 Huntington Avenue, Boston, MA, 02115, USA
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Changes in Radixin Expression and Interaction with Efflux Transporters in the Liver of Adjuvant-Induced Arthritic Rats. Inflammation 2019; 43:85-94. [PMID: 31654296 DOI: 10.1007/s10753-019-01097-9] [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: 10/25/2022]
Abstract
Scaffold proteins such as radixin help to modulate the plasma membrane localization and transport activity of the multidrug resistance-associated protein 2 (MRP2/ABCC2) and P-glycoprotein (P-gp/ABCB1) efflux transporters in the liver. We examined changes in radixin expression and interaction with efflux transporters in adjuvant-induced arthritic (AA) rats, an animal model of rheumatoid arthritis, as well as in human liver cancer (HepG2) cells because inflammation affects drug pharmacokinetics via the efflux transporters. The expression levels of radixin and phosphorylated radixin (p-radixin) were measured 24 h after treatment with inflammatory cytokines comprising tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 or sodium nitroprusside (SNP; a nitric oxide donor). The protein levels of radixin, MRP2, and P-gp in the rat liver were next examined. We also investigated whether inflammation affected the formation of complexes between radixin and MRP2 or P-gp. The mRNA and protein levels of radixin in HepG2 cells were significantly decreased by TNF-α treatment, while minimal changes were observed after treatment with IL-1β, IL-6 or SNP. TNF-α also significantly decreased the protein levels of p-radixin, suggesting that TNF-α inhibited the activation of radixin and thereby reduced the activity of the efflux transporters. Complex formation of radixin with MRP2 and P-gp was significantly decreased in AA rats but this was reversed by prednisolone and dexamethasone treatment, indicating that decreased interactions of radixin with MRP2 and P-gp likely occur during liver inflammation. These data suggest that liver inflammation reduces radixin function by decreasing its interactions with MRP2 and P-gp.
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9
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Role of ERK1/2 in TNFα-induced internalization of Abcc2 in rat hepatocyte couplets. Biochem Pharmacol 2019; 164:311-320. [DOI: 10.1016/j.bcp.2019.04.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/22/2019] [Indexed: 01/10/2023]
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Roma MG, Barosso IR, Miszczuk GS, Crocenzi FA, Pozzi EJS. Dynamic Localization of Hepatocellular Transporters: Role in Biliary Excretion and Impairment in Cholestasis. Curr Med Chem 2019; 26:1113-1154. [DOI: 10.2174/0929867325666171205153204] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 12/25/2022]
Abstract
Bile flow generation is driven by the vectorial transfer of osmotically active compounds from sinusoidal blood into a confined space, the bile canaliculus. Hence, localization of hepatocellular transporters relevant to bile formation is crucial for bile secretion. Hepatocellular transporters are localized either in the plasma membrane or in recycling endosomes, from where they can be relocated to the plasma membrane on demand, or endocytosed when the demand decreases. The balance between endocytic internalization/ exocytic targeting to/from this recycling compartment is therefore the main determinant of the hepatic capability to generate bile, and to dispose endo- and xenobiotics. Furthermore, the exacerbated endocytic internalization is a common pathomechanisms in both experimental and human cholestasis; this results in bile secretory failure and, eventually, posttranslational transporter downregulation by increased degradation. This review summarizes the proposed structural mechanisms accounting for this pathological condition (e.g., alteration of function, localization or expression of F-actin or F-actin/transporter cross-linking proteins, and switch to membrane microdomains where they can be readily endocytosed), and the mediators implicated (e.g., triggering of “cholestatic” signaling transduction pathways). Lastly, we discussed the efficacy to counteract the cholestatic failure induced by transporter internalization of a number of therapeutic experimental approaches based upon the use of compounds that trigger exocytic targetting of canalicular transporters (e.g., cAMP, tauroursodeoxycholate). This therapeutics may complement treatments aimed to transcriptionally improve transporter expression, by affording proper localization and membrane stability to the de novo synthesized transporters.
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Affiliation(s)
- Marcelo G. Roma
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
| | - Ismael R. Barosso
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
| | - Gisel S. Miszczuk
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
| | - Fernando A. Crocenzi
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
| | - Enrique J. Sánchez Pozzi
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
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Wang L, Wang J, Cai W, Shi Y, Zhou X, Guo G, Guo C, Huang X, Han Z, Zhang S, Ma S, Zhou X, Fan D, Gershwin ME, Han Y. A Critical Evaluation of Liver Pathology in Humans with Danon Disease and Experimental Correlates in a Rat Model of LAMP-2 Deficiency. Clin Rev Allergy Immunol 2018; 53:105-116. [PMID: 28124283 DOI: 10.1007/s12016-017-8598-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Danon disease is a genetic deficiency in lysosome-associated membrane protein 2 (LAMP-2), a highly glycosylated constituent of the lysosomal membrane and characterized by a cardiomyopathy, skeletal muscle myopathy, and cognitive impairment. Patients, however, often manifest hepatic abnormalities, but liver function has not been well evaluated and the syndrome is relatively uncommon. Hence, we have taken advantage of a rat that has been deleted of LAMP-2 to study the relative role of LAMP-2 on liver function. Interestingly, rats deficient in LAMP-2 develop a striking increase in serum alkaline phosphatase (ALP) and a decrease in bile flow compared with wild-type littermates. Importantly and by ultrastructural analysis, deficient rats manifest dilated canaliculi that lack microvilli with evidence of bile-containing bodies. Moreover, following bile duct ligation, LAMP-2-deficient rats develop rapid and severe evidence of advanced cholestasis, with an increase in serum bilirubin, as early as 6 h later. In wild-type control rats, multidrug resistance-associated protein 2 (Mrp2) normally concentrates at the bile canalicular membranes to secrete conjugated bilirubin into bile. However, in LAMP-2y/- rats, Mrp2 was detected in hepatocytes compared with other canalicular proteins including P-glycoproteins, dipeptidyl peptidase IV (CD26), and aminopeptidase (CD13). Our data further suggest that LAMP-2 interacts with the membrane cytoskeletal proteins radixin and F-actin in determining the localization of integral membrane proteins.
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Affiliation(s)
- Lu Wang
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Jingbo Wang
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Weile Cai
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Yongquan Shi
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Xinmin Zhou
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Guanya Guo
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Changcun Guo
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Xiaofeng Huang
- Center of Electron Microscope, The Fourth Military Medical University, Xi'an, Shaanxi Province, 710032, China
| | - Zheyi Han
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Shuai Zhang
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Shuoyi Ma
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Xia Zhou
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - Daiming Fan
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China
| | - M Eric Gershwin
- Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis School of Medicine, 451 Health Sciences Drive, Suite 6510, Davis, CA, 95616, USA.
| | - Ying Han
- Xijing Hospital of Digestive Diseases, The Fourth Military Medical University, 127 Changle West Road, Xi'an, Shaanxi Province, 710032, China.
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12
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Okamoto CT. Regulation of Transporters and Channels by Membrane-Trafficking Complexes in Epithelial Cells. Cold Spring Harb Perspect Biol 2017; 9:a027839. [PMID: 28246186 PMCID: PMC5666629 DOI: 10.1101/cshperspect.a027839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The vectorial secretion and absorption of fluid and solutes by epithelial cells is dependent on the polarized expression of membrane solute transporters and channels at the apical and basolateral membranes. The establishment and maintenance of this polarized expression of transporters and channels are affected by divers protein-trafficking complexes. Moreover, regulation of the magnitude of transport is often under control of physiological stimuli, again through the interaction of transporters and channels with protein-trafficking complexes. This review highlights the value in utilizing transporters and channels as cargo to characterize core trafficking machinery by which epithelial cells establish and maintain their polarized expression, and how this machinery regulates fluid and solute transport in response to physiological stimuli.
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Affiliation(s)
- Curtis T Okamoto
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089-9121
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Sharanek A, Burban A, Humbert L, Guguen-Guillouzo C, Rainteau D, Guillouzo A. Progressive and Preferential Cellular Accumulation of Hydrophobic Bile Acids Induced by Cholestatic Drugs Is Associated with Inhibition of Their Amidation and Sulfation. Drug Metab Dispos 2017; 45:1292-1303. [DOI: 10.1124/dmd.117.077420] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/12/2017] [Indexed: 11/22/2022] Open
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Yamamoto H, Umeda D, Matsumoto S, Kikuchi A. LDL switches the LRP6 internalization route from flotillin dependent to clathrin dependent in hepatic cells. J Cell Sci 2017; 130:3542-3556. [PMID: 28821575 DOI: 10.1242/jcs.202135] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 08/14/2017] [Indexed: 12/26/2022] Open
Abstract
Low-density lipoprotein (LDL) receptor-related protein 6 (LRP6) was originally identified as a co-receptor of the Wnt signalling pathway and has been shown to be involved in LDL transport. In polarized hepatocytes, many apical proteins are sorted to the basolateral membrane and then internalized and transported to the apical bile canalicular membrane - a process known as transcytosis. We show that LRP6 is transcytosed to the apical membrane of polarized hepatic HepG2 cells via a flotillin-dependent manner in the absence of LDL. LRP6 formed a complex with Niemann-Pick type C1-like 1 (NPC1L1), which is localized to the bile canalicular membrane of the liver and is involved in cholesterol absorption from the bile. LRP6 was required for apical membrane localization of NPC1L1 in the absence of LDL. Clathrin-dependent LRP6 internalization occurred in the presence of LDL, which resulted in trafficking of LRP6 to the lysosome, thereby reducing apical sorting of LRP6 and NPC1L1. These results suggest that LRP6 endocytosis proceeds by two routes, depending on the presence of LDL, and that LRP6 controls the intracellular destination of NPC1L1 in hepatocytes.
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Affiliation(s)
- Hideki Yamamoto
- Department of Molecular Biology and Biochemistry, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Daisuke Umeda
- Department of Molecular Biology and Biochemistry, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shinji Matsumoto
- Department of Molecular Biology and Biochemistry, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Akira Kikuchi
- Department of Molecular Biology and Biochemistry, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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15
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Mitogen-activated protein kinases are involved in hepatocanalicular dysfunction and cholestasis induced by oxidative stress. Arch Toxicol 2016; 91:2391-2403. [PMID: 27913845 DOI: 10.1007/s00204-016-1898-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/24/2016] [Indexed: 12/22/2022]
Abstract
In previous studies, we showed that the pro-oxidant model agent tert-butyl hydroperoxide (tBuOOH) induces alterations in hepatocanalicular secretory function by activating Ca2+-dependent protein kinase C isoforms (cPKC), via F-actin disorganization followed by endocytic internalization of canalicular transporters relevant to bile formation (Mrp2, Bsep). Since mitogen-activated protein kinases (MAPKs) may be downstream effectors of cPKC, we investigated here the involvement of the MAPKs of the ERK1/2, JNK1/2, and p38MAPK types in these deleterious effects. tBuOOH (100 µM, 15 min) increased the proportion of the active, phosphorylated forms of ERK1/2, JNK1/2, and p38MAPK, and panspecific PKC inhibition with bisindolylmaleimide-1 (100 nM) or selective cPKC inhibition with Gö6976 (1 μM) prevented the latter two events. In isolated rat hepatocyte couplets, tBuOOH (100 µM, 15 min) decreased the canalicular vacuolar accumulation of the fluorescent Bsep and Mrp2 substrates, cholylglycylamido fluorescein, and glutathione-methylfluorescein, respectively, and selective inhibitors of ERK1/2 (PD098059), JNK1/2 (SP600125), and p38MAPK (SB203580) partially prevented these alterations. In in situ perfused rat livers, these three MAPK inhibitors prevented tBuOOH (75 µM)-induced impairment of bile flow and the decrease in the biliary output of the Bsep and Mrp2 substrates, taurocholate, and dinitrophenyl-S-glutathione, respectively. The changes in Bsep/Mrp2 and F-actin localization induced by tBuOOH, as assessed by (immuno)fluorescence staining followed by analysis of confocal images, were prevented total or partially by the MAPK inhibitors. We concluded that MAPKs of the ERK1/2, JNK1/2, and p38MAPK types are all involved in cholestasis induced by oxidative stress, by promoting F-actin rearrangement and further endocytic internalization of canalicular transporters critical for bile formation.
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Haque A, Gheibi P, Gao Y, Foster E, Son KJ, You J, Stybayeva G, Patel D, Revzin A. Cell biology is different in small volumes: endogenous signals shape phenotype of primary hepatocytes cultured in microfluidic channels. Sci Rep 2016; 6:33980. [PMID: 27681582 PMCID: PMC5041105 DOI: 10.1038/srep33980] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 08/30/2016] [Indexed: 12/13/2022] Open
Abstract
The approaches for maintaining hepatocytes in vitro are aimed at recapitulating aspects of the native liver microenvironment through the use of co-cultures, surface coatings and 3D spheroids. This study highlights the effects of spatial confinement-a less studied component of the in vivo microenvironment. We demonstrate that hepatocytes cultured in low-volume microfluidic channels (microchambers) retain differentiated hepatic phenotype for 21 days whereas cells cultured in regular culture plates under identical conditions de-differentiate after 7 days. Careful consideration of nutrient delivery and oxygen tension suggested that these factors could not solely account for enhanced cell function in microchambers. Through a series of experiments involving microfluidic chambers of various heights and inhibition of key molecular pathways, we confirmed that phenotype of hepatocytes in small volumes was shaped by endogenous signals, both hepato-inductive growth factors (GFs) such as hepatocyte growth factor (HGF) and hepato-disruptive GFs such as transforming growth factor (TGF)-β1. Hepatocytes are not generally thought of as significant producers of GFs–this role is typically assigned to nonparenchymal cells of the liver. Our study demonstrates that, in an appropriate microenvironment, hepatocytes produce hepato-inductive and pro-fibrogenic signals at the levels sufficient to shape their phenotype and function.
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Affiliation(s)
- Amranul Haque
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA
| | - Pantea Gheibi
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA
| | - Yandong Gao
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA
| | - Elena Foster
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA
| | - Kyung Jin Son
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA
| | - Jungmok You
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA.,Department of Plant and Environmental New Resources, Kyung Hee University, Youngin-si, Gyeonggi-do, South Korea
| | - Gulnaz Stybayeva
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA
| | - Dipali Patel
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA
| | - Alexander Revzin
- Department of Biomedical Engineering, University of California Davis, CA 95616, USA
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17
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Dzierlenga AL, Clarke JD, Cherrington NJ. Nonalcoholic Steatohepatitis Modulates Membrane Protein Retrieval and Insertion Processes. ACTA ACUST UNITED AC 2016; 44:1799-1807. [PMID: 27604106 DOI: 10.1124/dmd.116.071415] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/25/2016] [Indexed: 01/29/2023]
Abstract
Interindividual variability in drug response in nonalcoholic steatohepatitis (NASH) can be mediated by altered regulation of drug metabolizing enzymes and transporters. Among these is the mislocalization of multidrug resistance-associated protein (MRP2)/Mrp2 away from the canalicular membrane, which results in decreased transport of MRP2/Mrp2 substrates. The exact mechanism of this mislocalization is unknown, although increased activation of membrane retrieval processes may be one possibility. The current study measures the activation status of various mediators implicated in the active membrane retrieval or insertion of membrane proteins to identify which processes may be important in rodent methionine and choline deficient diet-induced NASH. The mediators currently known to be associated with transporter mislocalization are stimulated by oxidative stressors and choleretic stimuli, which play a role in the pathogenesis of NASH. The activation of protein kinases PKA, PKCα, PKCδ, and PKCε and substrates radixin, myristoylated alanine-rich C-kinase substrate, and Rab11 were measured by comparing the expression, phosphorylation, and membrane translocation between control and NASH. Many of the mediators exhibited altered activation in NASH rats. Consistent with membrane retrieval of Mrp2, NASH rats exhibited a decreased phosphorylation of radixin and increased membrane localization of PKCδ and PKCε, thought to be mediators of radixin dephosphorylation. Altered activation of PKCδ, PKA, and PKCα may impair the Rab11-mediated active insertion of Mrp2. Overall, these data suggest alterations in membrane retrieval and insertion processes that may contribute to altered localization of membrane proteins in NASH.
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Affiliation(s)
- A L Dzierlenga
- Department of Pharmacology & Toxicology, University of Arizona, Tucson, Arizona
| | - J D Clarke
- Department of Pharmacology & Toxicology, University of Arizona, Tucson, Arizona
| | - N J Cherrington
- Department of Pharmacology & Toxicology, University of Arizona, Tucson, Arizona
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Kawase A, Handa A, Iwaki M. Effects of High-cholesterol Diet on Pravastatin Disposition in the Perfused Rat Liver. Eur J Drug Metab Pharmacokinet 2016; 42:519-526. [PMID: 27511381 DOI: 10.1007/s13318-016-0367-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND OBJECTIVES Various nutrients modulate the expression of transporters; however, the effect of a high-cholesterol (HC) diet on the expression and function of hepatic transporters remains unclear. Here, we examined the effects of an HC diet on drug disposition via hepatic transporters, including organic anion-transporting polypeptide (Oatp), multidrug resistance-associated protein (Mrp), and bile salt export pump (Bsep). METHODS In situ perfused rat liver system was performed. The levels of pravastatin, which is taken up into hepatocytes by Oatp and excreted into bile by Mrp2, in the perfusate and in bile were measured using high-performance liquid chromatography. RESULTS Pravastatin was rapidly eliminated in control and HC rats; however, the cumulative amounts of excreted in bile were significantly higher in HC rats than in controls possibly because of the enhanced bile flow in HC rats (0.93 ± 0.05 μL/min in control, and 1.22 ± 0.18 μL/min in HC). Real-time reverse-transcriptase polymerase chain reaction (PCR) and western blot assessment of the mRNA and protein levels of hepatic transporters showed a significant downregulation of the Oatp1a1 and Bsep proteins in HC rats, whereas no differences in Mrp2 and Mrp3 levels were observed between HC and control rats. The analysis of the localization of Mrp2 on the canalicular membrane by immunofluorescence showed no changes in HC rats, although Mrp2 was readily internalized from the canalicular membrane under specific conditions. CONCLUSIONS The findings of the present study indicate that the HC diet affected the biliary excretion of pravastatin concomitant with increased bile flow, despite minimal effects on the expression of hepatic transporters. The HC diet could promote the biliary excretion of other drugs and metabolites that are substrates of Mrp2 and Bsep.
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Affiliation(s)
- Atsushi Kawase
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, 577-8502, Japan.
| | - Ayumi Handa
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, 577-8502, Japan
| | - Masahiro Iwaki
- Department of Pharmacy, Faculty of Pharmacy, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, 577-8502, Japan
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19
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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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Suda J, Rockey DC, Karvar S. Akt2-Dependent Phosphorylation of Radixin in Regulation of Mrp-2 Trafficking in WIF-B Cells. Dig Dis Sci 2016; 61:453-63. [PMID: 26500117 DOI: 10.1007/s10620-015-3905-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/24/2015] [Indexed: 12/09/2022]
Abstract
BACKGROUND The dominant ezrin/radixin/moesin protein in hepatocytes is radixin, which plays an important role in mediating the binding of F-actin to the plasma membrane after a conformational activation by phosphorylation at Thr564. AIM Here we have investigated the importance of Akt-mediated radixin Thr564 phosphorylation on Mrp-2 distribution and function in WIF-B cells. Mrp-2 is an adenosine triphosphate (ATP)-binding cassette transporter that plays an important role in detoxification and chemoprotection by transporting a wide range of compounds, especially conjugates of lipophilic substances with glutathione, organic anions, and drug metabolites such as glucuronides. METHODS Akt1 and Akt2 expression were manipulated using dominant active and negative constructs as well as Akt1 and Akt2 siRNA. Cellular distribution of radixin and Mrp-2 was visualized by fluorescence microscopy. A 5-chloromethylfluorescein diacetate, which is a substrate of the Mrp-2 and is actively transported in canalicular lumina, was used to measure Mrp-2 function. RESULTS Radixin phosphorylation was significantly increased in wild-type and dominant active Akt2 transfected cells. Furthermore, radixin and Mrp-2 were localized at the canalicular membrane, similar to control cells. In contrast, overexpression of dominant negative Akt2, siRNA knockdown of Akt2 and a specific Akt inhibitor prevented radixin phosphorylation and led to alteration of normal radixin and Mrp-2 localization; inhibition of Akt2, but not Akt1 function led to radixin localization to the cytoplasmic space. In addition, dominant negative and Akt2 knockdown led to a dramatically impaired hepatocyte secretory response, while wild-type and dominant active Akt2 transfected cells exhibited increased 5-chloromethylfluorescein diacetate excretion. In contrast to Akt2, Akt1 was not associated with radixin phosphorylation. CONCLUSIONS These studies, therefore, identify Akt2 as a critical kinase that regulates radixin phosphorylation and leads to Mrp-2 translocation and function.
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Qin JJ, Wang JM, Du J, Zeng C, Han W, Li ZD, Xie J, Li GL. Radixin knockdown by RNA interference suppresses human glioblastoma cell growth in vitro and in vivo. Asian Pac J Cancer Prev 2015; 15:9805-12. [PMID: 25520109 DOI: 10.7314/apjcp.2014.15.22.9805] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Radixin, a member of the ERM (ezrin-radixin-moesin) family, plays important roles in cell motility, invasion and tumor progression. It is expressed in a variety of normal and neoplastic cells, including many types of epithelial and lymphoid examples. However, its function in glioblastomas remains elusive. Thus, in this study, radixin gene expression was first examined in the glioblastoma cells, then suppressed with a lentivirus-mediated short-hairpin RNA (shRNA) method.We found that there were high levels of radixin expression in glioblastoma U251cells. Radixin shRNA caused down-regulation of radixin gene expression and when radixin-silenced cells were implanted into nude mice, tumor growth was significantly inhibited as compared to blank control cells or non- sense shRNA cells. In addition, microvessel density in the tumors was significantly reduced. Thrombospondin-1 (TSP-1) and E-cadherin were up-regulated in radixin- suppressed glioblastoma U251 cells. In contrast, MMP9 was down-regulated. Taken together, our findings suggest that radixin is involved in GBM cell migration and invasion, and implicate TSP-1, E-cadherin and MMP9 as metastasis-inducing factors.
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Affiliation(s)
- Jun-Jie Qin
- Department of Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China E-mail : ,
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Henry C, Saadaoui B, Bouvier F, Cebo C. Phosphoproteomics of the goat milk fat globule membrane: New insights into lipid droplet secretion from the mammary epithelial cell. Proteomics 2015; 15:2307-17. [PMID: 25737190 DOI: 10.1002/pmic.201400245] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 01/26/2015] [Accepted: 02/26/2015] [Indexed: 12/24/2022]
Abstract
Mechanisms of milk lipid secretion are highly controversial. Analyzing the fine protein composition of the "milk fat globule membrane" (MFGM), the triple-layered membrane surrounding milk lipid droplets (LDs) can provide mechanistic clues to better understand LD biosynthesis and secretion pathways in mammary epithelial cells (MECs). We therefore combined a high-sensitive Q-Exactive LC-MS/MS analysis of MFGM-derived peptides to the use of an in-house database intended to improve protein identification in the goat species. Using this approach, we performed the identification of 442 functional groups of proteins in the MFGM from goat milk. To get a more dynamic view of intracellular mechanisms driving LD dynamics in the MECs, we decided to investigate for the first time whether MFGM proteins were phosphorylated. MFGM proteins were sequentially digested by lysine-C and trypsin proteases and the resulting peptides were fractionated by a strong cation exchange chromatography. Titanium beads were used to enrich phosphopeptides from strong cation exchange chromatography eluted fractions. This approach lets us pinpoint 271 sites of phosphorylation on 124 unique goat MFGM proteins. Enriched GO terms associated with phosphorylated MFGM proteins were protein transport and actin cytoskeleton organization. Gained data are discussed with regard to lipid secretory mechanisms in the MECs. All MS data have been deposited in the ProteomeXchange with identifier PXD001039 (http://proteomecentral.proteomexchange.org/dataset/PXD001039).
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Affiliation(s)
- Céline Henry
- INRA, UMR1319, MICALIS, Plateforme PAPSSO (Plateforme d'Analyse Protéomique Paris Sud Ouest), Jouy-en-Josas, France
| | - Besma Saadaoui
- Faculté des Sciences de Gabès, Université de Gabès, cité Erriadh Zrig, Tunisia
| | | | - Christelle Cebo
- INRA, UMR1313 Unité Génétique Animale et Biologie Intégrative, Equipe Génomique Fonctionnelle et Physiologie de la Glande Mammaire (GFP-GM), Jouy-en-Josas, France
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Suda J, Rockey DC, Karvar S. Phosphorylation dynamics of radixin in hypoxia-induced hepatocyte injury. Am J Physiol Gastrointest Liver Physiol 2015; 308:G313-24. [PMID: 25501552 DOI: 10.1152/ajpgi.00369.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The most prominent ezrin-radixin-moesin protein in hepatocytes is radixin, which is localized primarily at the canalicular microvilli and appears to be important in regulation of cell polarity and in localizing the multidrug resistance-associated protein 2 (Mrp-2) function. Our aim was to investigate how hypoxia affects radixin distribution and Mrp-2 function. We created wild-type and mutant constructs (in adenoviral vectors), which were expressed in WIF-B cells. The cellular distribution of Mrp-2 and radixin was visualized by fluorescence microscopy, and a 5-chloromethylfluorescein diacetate (CMFDA) assay was used to measure Mrp-2 function. Under usual conditions, cells infected with wild-type radixin, nonphosphorylatable radixin-T564A, and radixin-T564D (active phospho-mimicking mutant) were found to be heavily expressed in canalicular membrane compartment vacuoles, typically colocalizing with Mrp-2. In contrast, after hypoxia for 24 h, both endogenous and overexpressed wild-type radixin and the radixin-T564A mutant were found to be translocated to the cytoplasmic space. However, distribution of the radixin-T564D mutant, which mimics constant phosphorylation, was remarkably different, being associated with canalicular membranes even in hypoxic conditions. This dominant-active construct also prevented dissociation of radixin from the plasma membrane. Hypoxia also led to Mrp-2 mislocalization and caused Mrp-2 to be dissociated from radixin; the radixin phospho-mimicking mutant (T564D) abrogated this effect of hypoxia. Finally, hypoxia diminished the secretory response (measured using the CMFDA assay) in WIF-B cells, and the dominant-active construct (radixin-T567D) rescued this phenotype. Taken collectively, these findings suggest that radixin regulates Mrp-2 localization and function in hepatocytes and is important in hypoxic liver injury.
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Affiliation(s)
- Jo Suda
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Don C Rockey
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Serhan Karvar
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
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Genetic variants may play an important role in mRNA-miRNA interaction: evidence for haplotype-dependent downregulation of ABCC2 (MRP2) by miRNA-379. Pharmacogenet Genomics 2014; 24:283-91. [PMID: 24743544 DOI: 10.1097/fpc.0000000000000046] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND The functional influence of single-nucleotide polymorphisms (SNPs) of the ATP-binding cassette (ABC) transporter ABCC2 (MRP2) has been characterized in numerous studies. The aim of this study was to address the question of whether distinct ABCC2 haplotypes, which differ in their mRNA secondary structures, show an influence on the degree of mRNA and protein downregulation through miRNA interaction. METHODS A model using human peripheral blood monocytic cells (PBMCs) isolated from healthy Caucasian volunteers, with three defined ABCC2 haplotypes comprising the 5'-UTR SNP -24C>T, the 1249G>A SNP (V417I), and the silent 3972C>T SNP, was outlined. Cells were transiently transfected with miRNA-379, already known to target ABCC2 in HepG2 cells. RESULTS ABCC2 was downregulated through miR-379 in a haplotype-dependent manner: the wild-type CGC/CGC was modestly affected (mRNA: -12.7±4.2%, protein: -9.9±0.1%), whereas variant haplotypes were more strongly suppressed: CGT/CGT (mRNA: -36.7±2.4%, protein: -21.6±0.4%) and TGT/TGT (mRNA: -55.7±1.2%, protein: -46.3±4.0%). In addition, glutathione-methylfluorescein efflux was significantly reduced in miR-379-transfected peripheral blood monocytic cells corresponding to ABCC2 protein expression. CONCLUSION This observation may suggest a differential suppression of ABCC2 by miR-379 caused by haplotype-dependent differences in mRNA secondary structures, resulting in changes in mRNA target accessibility or mRNA stability.
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Kawase A, Sakata M, Yada N, Nakasaka M, Shimizu T, Kato Y, Iwaki M. Decreased radixin function for ATP-binding cassette transporters in liver in adjuvant-induced arthritis rats. J Pharm Sci 2014; 103:4058-4065. [PMID: 25331966 DOI: 10.1002/jps.24210] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 09/20/2014] [Accepted: 09/22/2014] [Indexed: 01/22/2023]
Abstract
Pathophysiological changes are associated with alterations in the expression and function of numerous ADME-related proteins. We have previously demonstrated that the membrane localization of ATP-binding cassette (ABC) transporters in liver was decreased without change of total expression levels in adjuvant-induced arthritis (AA) in rats. Ezrin/radixin/moesin (ERM) proteins are involved in localization of some ABC transporters in canalicular membrane. The mRNA levels of radixin decreased significantly in liver but not kidney, small intestine, and brain. The mRNA levels of ezrin and moesin did not change in AA. The membrane localization of radixin was reduced in liver of AA and the ratios of activated radixin (p-radixin) to total radixin were decreased in AA, although the protein levels of radixin did not change in homogenate and membrane protein. To clarify whether AA affects the linker functions of ERM proteins, we examined the interactions between ERM proteins and ABC transporters. The interactions between radixin and ABC transporters were decreased in AA. In vitro studies using human hepatoma HepG2 cells showed that interleukin-1β decreased the mRNA levels of radixin and colocalization of radixin and Mrp2. Our results show that the decreased radixin functions affect the interaction between radixin and ABC transporters in inflammation.
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Affiliation(s)
- Atsushi Kawase
- Department of Pharmacy, School of Pharmacy, Kinki University, Osaka 577-8502, Japan
| | - Misato Sakata
- Department of Pharmacy, School of Pharmacy, Kinki University, Osaka 577-8502, Japan
| | - Nagisa Yada
- Department of Pharmacy, School of Pharmacy, Kinki University, Osaka 577-8502, Japan
| | - Misaki Nakasaka
- Department of Pharmacy, School of Pharmacy, Kinki University, Osaka 577-8502, Japan
| | - Takuya Shimizu
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-1192, Japan
| | - Yukio Kato
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-1192, Japan
| | - Masahiro Iwaki
- Department of Pharmacy, School of Pharmacy, Kinki University, Osaka 577-8502, Japan.
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Karvar S, Suda J, Zhu L, Rockey DC. Distribution dynamics and functional importance of NHERF1 in regulation of Mrp-2 trafficking in hepatocytes. Am J Physiol Cell Physiol 2014; 307:C727-37. [PMID: 25163515 DOI: 10.1152/ajpcell.00011.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Na(+)/H(+) exchanger regulatory factor 1 (NHERF1) is a multifunctional scaffolding protein that interacts with receptors and ion transporters in its PDZ domains and with the ezrin-radixin-moesin (ERM) family of proteins in its COOH terminus. The role of NHERF1 in hepatocyte function remains largely unknown. We examine the distribution and physiological significance of NHERF1 and multidrug resistance-associated protein 2 (Mrp-2) in hepatocytes. A WT radixin binding site mutant (F355R) and NHERF1 PDZ1 and PDZ2 domain adenoviral mutant constructs were tagged with yellow fluorescent protein and expressed in polarized hepatocytes to study localization and function of NHERF1. Cellular distribution of NHERF1 and radixin was visualized by fluorescence microscopy. A 5-chloromethylfluorescein diacetate (CMFDA) assay was used to characterize Mrp-2 function. Similar to Mrp-2, WT NHERF1 and the NHERF1 PDZ2 deletion mutant were localized to the canalicular membrane. In contrast, the radixin binding site mutant (F355R) and the NHERF1 PDZ1 deletion mutant, which interacts poorly with Mrp-2, were rarely associated with the canalicular membrane. Knockdown of NHERF1 led to dramatically impaired CMFDA secretory response. Use of CMFDA showed that the NHERF1 PDZ1 and F355R mutants were devoid of a secretory response, while WT NHERF1-infected cells exhibited increased secretion of glutathione-methylfluorescein. The data indicate that NHERF1 interacts with Mrp-2 via the PDZ1 domain of NHERF1 and, furthermore, that NHERF1 is essential for maintaining the localization and function of Mrp-2.
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Affiliation(s)
- Serhan Karvar
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina;
| | - Jo Suda
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Lixin Zhu
- Digestive Diseases and Nutrition Center, University at Buffalo, State University of New York, Buffalo, New York
| | - Don C Rockey
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
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Apicobasal polarity controls lymphocyte adhesion to hepatic epithelial cells. Cell Rep 2014; 8:1879-1893. [PMID: 25242329 DOI: 10.1016/j.celrep.2014.08.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 06/25/2014] [Accepted: 08/04/2014] [Indexed: 02/08/2023] Open
Abstract
Loss of apicobasal polarity is a hallmark of epithelial pathologies. Leukocyte infiltration and crosstalk with dysfunctional epithelial barriers are crucial for the inflammatory response. Here, we show that apicobasal architecture regulates the adhesion between hepatic epithelial cells and lymphocytes. Polarized hepatocytes and epithelium from bile ducts segregate the intercellular adhesion molecule 1 (ICAM-1) adhesion receptor onto their apical, microvilli-rich membranes, which are less accessible by circulating immune cells. Upon cell depolarization, hepatic ICAM-1 becomes exposed and increases lymphocyte binding. Polarized hepatic cells prevent ICAM-1 exposure to lymphocytes by redirecting basolateral ICAM-1 to apical domains. Loss of ICAM-1 polarity occurs in human inflammatory liver diseases and can be induced by the inflammatory cytokine tumor necrosis factor alpha (TNF-α). We propose that adhesion receptor polarization is a parenchymal immune checkpoint that allows functional epithelium to hamper leukocyte binding. This contributes to the haptotactic guidance of leukocytes toward neighboring damaged or chronically inflamed epithelial cells that expose their adhesion machinery.
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28
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Anwer MS. Role of protein kinase C isoforms in bile formation and cholestasis. Hepatology 2014; 60:1090-7. [PMID: 24700589 PMCID: PMC4141907 DOI: 10.1002/hep.27088] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 02/13/2014] [Indexed: 12/11/2022]
Abstract
Transhepatic solute transport provides the osmotic driving force for canalicular bile formation. Choleretic and cholestatic agents affect bile formation, in part, by altering plasma membrane localizations of transporters involved in bile formation. These short-term dynamic changes in transporter location are highly regulated posttranslational events requiring various cellular signaling pathways. Interestingly, both choleretic and cholestatic agents activate the same intracellular signaling kinases, such as phosphoinositide-3-kinase (PI3K), protein kinase C (PKC), and mitogen-activated protein kinase (MAPK). An emerging theme is that choleretic and cholestatic effects may be mediated by different isoforms of these kinases. This is most evident for PKC-mediated regulation of plasma membrane localization of Na+-taurocholate cotransporting polypeptide (NTCP) and multidrug resistance-associated protein 2 (MRP2) by conventional PKCα (cPKCα), novel PKCδ (nPKCδ), nPKCε, and atypical PKCζ (aPKCζ). aPKCζ may mediate choleretic effects by inserting NTCP into the plasma membrane, and nPKCε may mediate cholestatic effects by retrieving MRP2 from the plasma membrane. On the other hand, cPKCα and nPKCδ may be involved in choleretic, cholestatic, and anticholestatic effects by inserting, retrieving, and inhibiting retrieval of transporters, respectively. The effects of PKC isoforms may be mediated by phosphorylation of the transporters, actin binding proteins (radixin and myristoylated alanine-rich C kinase substrate), and Rab proteins. Human NTCP plays an important role in the entry of hepatitis B and D viruses into hepatocytes and consequent infection. Thus, PKCs, by regulating NTCP trafficking, may also play an important role in hepatic viral infections.
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Affiliation(s)
- M Sawkat Anwer
- Department of Biomedical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA
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Kawase A. Alterations in Expression and Function of ABC Transporters and ERM Proteins in Inflammation. YAKUGAKU ZASSHI 2014; 134:925-9. [DOI: 10.1248/yakushi.14-00160] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Atsushi Kawase
- Department of Pharmacy, Faculty of Pharmacy, Kinki University
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Hegde M, Jindal R, Bhushan A, Bale SS, McCarty WJ, Golberg I, Usta OB, Yarmush ML. Dynamic interplay of flow and collagen stabilizes primary hepatocytes culture in a microfluidic platform. LAB ON A CHIP 2014; 14:2033-9. [PMID: 24770663 PMCID: PMC4036071 DOI: 10.1039/c4lc00071d] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The creation of stable flow cultures of hepatocytes is highly desirable for the development of platforms for drug toxicity screening, bio-artificial liver support devices, and models for investigating liver physiology and pathophysiology. Given that hepatocytes cultured using the collagen overlay or in 'sandwich' configuration maintain a wide range of differentiated functions, we describe a simple method for adapting this culture configuration within a microfluidic device. The device design consists of a porous membrane sandwiched between two layers of PDMS resulting in a two-chambered device. In the bottom chamber, hepatocytes are cultured in the collagen sandwich configuration, while the top chamber is accessible for flow. We demonstrate that hepatocytes cultured under flow exhibit higher albumin and urea secretions and induce cytochrome P450 1A1 activity in comparison to static cultures. Furthermore, over two weeks, hepatocytes cultured under flow show a well-connected cellular network with bile canaliculi formation, whereas static cultures show formation of gaps in the cellular network that progressively increase over time. Although enhanced functional response of hepatocytes cultured under flow has been observed in multiple prior studies, the exact mechanism for this flow induced effect remains unknown. In our work, we identified that hepatocytes secrete a higher level of collagen in the flow cultures; inhibiting collagen secretion within the flow cultures reduced albumin secretion and restored the appearance of gaps in the cellular network similar to the static cultures. These results demonstrate the importance of the increased collagen secretion by hepatocytes cultured under flow as a mechanism to maintain a well-connected cellular network and a differentiated function.
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Affiliation(s)
| | - Rohit Jindal
- corresponding authors: Dr. Rohit Jindal, Center for Engineering in Medicine (CEM), Massachusetts General Hospital, Harvard Medical School, Shriners Hospital for Children, 51 Blossom Street, Boston, MA 02114, . Dr. Martin L. Yarmush, Center for Engineering in Medicine (CEM), Massachusetts General Hospital, Harvard Medical School, Shriners Hospital for Children, 51 Blossom Street, Boston, MA 02114,
| | | | | | | | | | | | - Martin L. Yarmush
- corresponding authors: Dr. Rohit Jindal, Center for Engineering in Medicine (CEM), Massachusetts General Hospital, Harvard Medical School, Shriners Hospital for Children, 51 Blossom Street, Boston, MA 02114, . Dr. Martin L. Yarmush, Center for Engineering in Medicine (CEM), Massachusetts General Hospital, Harvard Medical School, Shriners Hospital for Children, 51 Blossom Street, Boston, MA 02114,
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Nakada SL, Crothers JM, Machen TE, Forte JG. Apical vacuole formation by gastric parietal cells in primary culture: effect of low extracellular Ca2+. Am J Physiol Cell Physiol 2012; 303:C1301-11. [PMID: 23099641 DOI: 10.1152/ajpcell.00244.2012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In primary culture, the gastric parietal cell's deeply invaginated apical membrane, seen in microscopy by phalloidin binding to F-actin (concentrated in microvilli and a subapical web), is engulfed into the cell, separated from the basolateral membrane (which then becomes the complete plasma membrane), and converted, from a lacy interconnected system of canaliculi, into several separate vacuoles. In this study, vacuolar morphology was achieved by 71% of parietal cells 8 h after typical collagenase digestion of rabbit gastric mucosa, but the tight-junctional protein zonula occludens-1 (ZO-1) was completely delocalized after ∼2 h, when cells were ready for culturing. Use of low-Ca(2+) medium (4 mM EGTA) to release cells quickly from gastric glands yielded parietal cells in which ZO-1 was seen in a small spot or ring, a localization quickly lost if these cells were then cultured in normal Ca(2+) but remaining up to 20 h if they were cultured in low Ca(2+). The cells in low Ca(2+) mostly retained, at 20 h, an intermediate morphology of many bulbous canalicular expansions ("prevacuoles"), seemingly with narrow interconnections. Histamine stimulation of 20-h cells with intermediate morphology caused colocalization of proton-pumping H-K-ATPase with canaliculi and prevacuoles but little swelling of those structures, consistent with a remaining apical pore through which secreted acid could escape. Apparent canalicular interconnections, lack of stimulated swelling, and lingering ZO-1 staining indicate inhibition of membrane fission processes that separate apical from basolateral membrane and vacuoles from each other, suggesting an important role for extracellular Ca(2+) in these, and possibly other, endocytotic processes.
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Affiliation(s)
- Stephanie L Nakada
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA
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Chen SD, Song MM, Zhong ZQ, Li N, Wang PL, Cheng S, Bai RX, Yuan HS. Knockdown of Radixin by RNA interference Suppresses the Growth of Human Pancreatic Cancer Cells in Vitro and in Vivo. Asian Pac J Cancer Prev 2012; 13:753-9. [DOI: 10.7314/apjcp.2012.13.3.753] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Valderrama F, Thevapala S, Ridley AJ. Radixin regulates cell migration and cell-cell adhesion through Rac1. J Cell Sci 2012; 125:3310-9. [DOI: 10.1242/jcs.094383] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The ERM proteins ezrin, radixin and moesin are adaptor proteins that link plasma membrane receptors to the actin cytoskeleton. Ezrin and moesin have been implicated in cell polarization and cell migration, but little is known about the involvement of radixin in these processes. Here we show that radixin is required for migration of PC3 prostate cancer cells, and that radixin, but not ezrin or moesin, depletion by RNAi increases cell spread area and cell-cell adhesion mediated by adherens junctions. Radixin depletion also alters actin organization and distribution of active phosphorylated ezrin and moesin. Similar effects were observed in MDA-MB-231 breast cancer cells. The phenotype of radixin-depleted cells is similar to that induced by constitutively active Rac1, and Rac1 is required for the radixin knockdown phenotype. Radixin depletion also increases the activity of Rac1 but not Cdc42 or RhoA. Analysis of Rac guanine nucleotide exchange factors (GEFs) suggests that radixin affects the activity of Vav GEFs. Indeed, Vav GEF depletion reverts the phenotype of radixin knockdown and reduces the effect of radixin knockdown on Rac1 activity. Our results indicate that radixin plays an important role in promoting cell migration by regulating Rac1-mediated epithelial polarity and formation of adherens junctions through Vav GEFs.
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Constitutively active ezrin increases membrane tension, slows migration, and impedes endothelial transmigration of lymphocytes in vivo in mice. Blood 2011; 119:445-53. [PMID: 22106344 DOI: 10.1182/blood-2011-07-368860] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
ERM (ezrin, radixin moesin) proteins in lymphocytes link cortical actin to plasma membrane, which is regulated in part by ERM protein phosphorylation. To assess whether phosphorylation of ERM proteins regulates lymphocyte migration and membrane tension, we generated transgenic mice whose T-lymphocytes express low levels of ezrin phosphomimetic protein (T567E). In these mice, T-cell number in lymph nodes was reduced by 27%. Lymphocyte migration rate in vitro and in vivo in lymph nodes decreased by 18% to 47%. Lymphocyte membrane tension increased by 71%. Investigations of other possible underlying mechanisms revealed impaired chemokine-induced shape change/lamellipod extension and increased integrin-mediated adhesion. Notably, lymphocyte homing to lymph nodes was decreased by 30%. Unlike most described homing defects, there was not impaired rolling or sticking to lymph node vascular endothelium but rather decreased migration across that endothelium. Moreover, decreased numbers of transgenic T cells in efferent lymph suggested defective egress. These studies confirm the critical role of ERM dephosphorylation in regulating lymphocyte migration and transmigration. Of particular note, they identify phospho-ERM as the first described regulator of lymphocyte membrane tension, whose increase probably contributes to the multiple defects observed in the ezrin T567E transgenic mice.
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Sekine S, Ito K, Saeki J, Horie T. Interaction of Mrp2 with radixin causes reversible canalicular Mrp2 localization induced by intracellular redox status. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1427-34. [DOI: 10.1016/j.bbadis.2011.07.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 07/25/2011] [Accepted: 07/26/2011] [Indexed: 12/28/2022]
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