Differential regulation of angiotensin II-induced extracellular signal regulated kinase-1/2 and -5 in progressive glomerulonephritis

Aim: Extracellular signal regulated kinase (ERK)1/2 and ERK5 are key kinases of the signaling pathways involved in various cellular responses to kidney injury; however, the mechanistic links between those kinase and renin-angiotensin system (RAS) activation in glomerulonephritis (GN) have not been fully elucidated. In this study, we sought to clarify the potential roles of ERK1/2 and ERK5 via RAS activation in the pathogenesis of GN.
Methods: A rat model of progressive GN was induced by anti-glomerular basement membrane (GBM) injection and the signal transduction pathway in angiotensin II (Ang II)-induced glomerular pathologic alterations were investigated in primary cultured mesangial cells (MCs). Results: Rats developed typical cellular crescents in glomeruli on day 7 that progressed to severe fibrocellular crescents and glomerulosclerosis on day 28. Strong expression of phospho-ERK1/2 was observed on day 7 and phospho-ERK5 expression was markedly increased on day 28 of GN. An angiotensin II type 1 receptor blocker (ARB) suppressed those augmentations. Moreover, ARB treatment attenuated the increases in macrophage infiltration and PCNA-positive cells observed on day 7 in GN rats, as well as the increase in collagen type 1 expression on day 28. Consistently, MCs stimulated by Ang II showed significant increases in proliferation and the expression of MCP-1 and collagen type 1. Interestingly, while the ERK1/2 inhibitor PD98059 abolished the elevations in MCP-1 expression and cell proliferation, the ERK5 inhibitor BIX02189 abrogated the elevation in collagen type 1 expression.
Conclusion: Altogether, these data suggest that ERK1/2 regulates acute inflammatory reactions, while ERK5 promotes the development of RAS-induced chronic glomerular fibrosis activation in GN.

内容要旨・審査要旨・論文本文の公開:
内容要旨・審査要旨 : LID201606071001.pdf
論文本文 : k2905_fulltext.pdf
著者の申請により要約(2016-09-29公開)に替えて論文全文を公開(2018-06-22)
本論文は, 著者Takashi Nagaiの学位論文として提出され, 学位審査・授与の対象となっている。