Claudin-2 suppresses GEF-H1, RHOA, and MRTF, thereby impacting proliferation and profibrotic phenotype of tubular cells
| Autor: | Pam Speight, Jenny Xiao, Qinghong Dan, Razieh Rabani, Yixuan Shi, R. Todd Alexander, Shaista Anwer, Shruthi Venugopal, Mei Ding, Andras Kapus, Katalin Szászi, Wanling Pan |
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| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Male RHOA Swine medicine.medical_treatment Biochemistry 03 medical and health sciences Mice medicine Gene silencing Animals Humans Claudin Molecular Biology Actin Water transport 030102 biochemistry & molecular biology biology Tight junction Chemistry Tumor Necrosis Factor-alpha Growth factor Cell Biology Cell biology Mice Inbred C57BL 030104 developmental biology Kidney Tubules Phenotype Claudins biology.protein Trans-Activators LLC-PK1 Cells Tumor necrosis factor alpha Female rhoA GTP-Binding Protein Rho Guanine Nucleotide Exchange Factors Ureteral Obstruction |
| Zdroj: | J Biol Chem |
| ISSN: | 1083-351X |
| Popis: | The tight junctional pore-forming protein claudin-2 (CLDN-2) mediates paracellular Na(+) and water transport in leaky epithelia and alters cancer cell proliferation. Previously, we reported that tumor necrosis factor-α time-dependently alters CLDN-2 expression in tubular epithelial cells. Here, we found a similar expression pattern in a mouse kidney injury model (unilateral ureteral obstruction), consisting of an initial increase followed by a drop in CLDN-2 protein expression. CLDN-2 silencing in LLC-PK(1) tubular cells induced activation and phosphorylation of guanine nucleotide exchange factor H1 (GEF-H1), leading to Ras homolog family member A (RHOA) activation. Silencing of other claudins had no such effects, and re-expression of an siRNA-resistant CLDN-2 prevented RHOA activation, indicating specific effects of CLDN-2 on RHOA. Moreover, kidneys from CLDN-2 knockout mice had elevated levels of active RHOA. Of note, CLDN-2 silencing reduced LLC-PK1 cell proliferation and elevated expression of cyclin-dependent kinase inhibitor P27 (P27KIP1) in a GEF-H1/RHOA-dependent manner. P27KIP1 silencing abrogated the effects of CLDN-2 depletion on proliferation. CLDN-2 loss also activated myocardin-related transcription factor (MRTF), a fibrogenic RHOA effector, and elevated expression of connective tissue growth factor and smooth muscle actin. Finally, CLDN-2 down-regulation contributed to RHOA activation and smooth muscle actin expression induced by prolonged tumor necrosis factor-α treatment, because they were mitigated by re-expression of CLDN-2. Our results indicate that CLDN-2 suppresses GEF-H1/RHOA. CLDN-2 down-regulation, for example, by inflammation, can reduce proliferation and promote MRTF activation through RHOA. These findings suggest that the initial CLDN-2 elevation might aid epithelial regeneration, and CLDN-2 loss could contribute to fibrotic reprogramming. |
| Databáze: | OpenAIRE |
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