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- Saarikangas, J, et al.
(author)
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Missing-in-metastasis MIM/MTSS1 promotes actin assembly at intercellular junctions and is required for integrity of kidney epithelia
- 2011
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In: Journal of cell science. - : The Company of Biologists. - 1477-9137 .- 0021-9533. ; 124:8Pt 8, s. 1245-1255
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Journal article (peer-reviewed)abstract
- MIM/MTSS1 is a tissue-specific regulator of plasma membrane dynamics, whose altered expression levels have been linked to cancer metastasis. MIM deforms phosphoinositide-rich membranes through its I-BAR domain and interacts with actin monomers through its WH2 domain. Recent work proposed that MIM also potentiates Sonic hedgehog (Shh)-induced gene expression. Here, we generated MIM mutant mice and found that full-length MIM protein is dispensable for embryonic development. However, MIM-deficient mice displayed a severe urinary concentration defect caused by compromised integrity of kidney epithelia intercellular junctions, which led to bone abnormalities and end-stage renal failure. In cultured kidney epithelial (MDCK) cells, MIM displayed dynamic localization to adherens junctions, where it promoted Arp2/3-mediated actin filament assembly. This activity was dependent on the ability of MIM to interact with both membranes and actin monomers. Furthermore, results from the mouse model and cell culture experiments suggest that full-length MIM is not crucial for Shh signaling, at least during embryogenesis. Collectively, these data demonstrate that MIM modulates interplay between the actin cytoskeleton and plasma membrane to promote the maintenance of intercellular contacts in kidney epithelia.
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- Kujala, M, et al.
(author)
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SLC26A6 and SLC26A7 anion exchangers have a distinct distribution in human kidney
- 2005
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In: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 101:2, s. E50-E58
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Journal article (peer-reviewed)abstract
- <i>Background:</i> The anion transporters SLC26A6 (PAT1) and SLC26A7, transporting at least chloride, oxalate, sulfate and bicarbonate, show a distinct expression and function in different mammalian species. They are expressed in kidney, but their exact localization in human kidney has not been studied. We therefore examined SLC26A6 and A7 expression in human kidneys. <i>Methods:</i> The localization of SLC26A6 and A7 in different segments of human nephrons was studied by RT-PCR and immunohistochemistry by comparing to the tubular markers PNRA, CD10, Tamm-Horsfall antigen, high molecular weight cytokeratin, CK7, AQP2 and H<sup>+</sup>V-ATPase. <i>Results:</i> In human kidney, SLC26A6 is expressed in distal segments of proximal tubules, parts of the thin and thick ascending limbs of Henle’s loops, macula densa, distal convoluted tubules and a subpopulation of intercalated cells of collecting ducts. SLC26A7 is expressed in extraglomerular mesangial cells and a subpopulation of intercalated cells of collecting ducts. <i>Conclusion:</i> Our results show that in human kidney SLC26A6 and A7 have a distinct, partially overlapping expression in distal segments of nephrons. The distribution partly differs from that found previously in rodent kidneys.
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- Li, H, et al.
(author)
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Development of the urogenital system is regulated via the 3'UTR of GDNF
- 2019
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In: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1, s. 5302-
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Journal article (peer-reviewed)abstract
- Mechanisms controlling ureter lenght and the position of the kidney are poorly understood. Glial cell-line derived neurotrophic factor (GDNF) induced RET signaling is critical for ureteric bud outgrowth, but the function of endogenous GDNF in further renal differentiation and urogenital system development remains discursive. Here we analyzed mice where 3′ untranslated region (UTR) of GDNF is replaced with sequence less responsive to microRNA-mediated regulation, leading to increased GDNF expression specifically in cells naturally transcribing Gdnf. We demonstrate that increased Gdnf leads to short ureters in kidneys located in an abnormally caudal position thus resembling human pelvic kidneys. High GDNF levels expand collecting ductal progenitors at the expense of ureteric trunk elongation and result in expanded tip and short trunk phenotype due to changes in cell cycle length and progenitor motility. MEK-inhibition rescues these defects suggesting that MAPK-activity mediates GDNF’s effects on progenitors. Moreover, Gdnf hyper mice are infertile likely due to effects of excess GDNF on distal ureter remodeling. Our findings suggest that dysregulation of GDNF levels, for example via alterations in 3′UTR, may account for a subset of congenital anomalies of the kidney and urinary tract (CAKUT) and/or congenital infertility cases in humans and pave way to future studies.
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