PMID- 28720662 OWN - NLM STAT- MEDLINE DCOM- 20171129 LR - 20211204 IS - 1939-4586 (Electronic) IS - 1059-1524 (Print) IS - 1059-1524 (Linking) VI - 28 IP - 19 DP - 2017 Sep 15 TI - Proximal tubule apical endocytosis is modulated by fluid shear stress via an mTOR-dependent pathway. PG - 2508-2517 LID - 10.1091/mbc.E17-04-0211 [doi] AB - Cells lining the proximal tubule (PT) have unique membrane specializations that are required to maintain the high-capacity ion transport and endocytic functions of this nephron segment. PT cells in vivo acutely regulate ion transport in response to changes in glomerular filtration rate (GFR) to maintain glomerulotubular balance. PT cells in culture up-regulate endocytic capacity in response to acute changes in fluid shear stress (FSS); however, it is not known whether GFR modulates PT endocytosis to enable maximally efficient uptake of filtered proteins in vivo. Here, we show that cells cultured under continuous FSS develop an expanded apical endocytic pathway and increased endocytic capacity and lysosomal biogenesis. Furthermore, endocytic capacity in fully differentiated cells is rapidly modulated by changes in FSS. PT cells exposed to continuous FSS also acquired an extensive brush border and basolateral membrane invaginations resembling those observed in vivo. Culture under suboptimal levels of FSS led to intermediate phenotypes, suggesting a threshold effect. Cells exposed to FSS expressed higher levels of key proteins necessary for PT function, including ion transporters, receptors, and membrane-trafficking machinery, and increased adenine nucleotide levels. Inhibition of the mechanistic target of rapamycin (mTOR) using rapamycin prevented the increase in cellular energy levels, lysosomal biogenesis, and endocytic uptake, suggesting that these represent a coordinated differentiation program. In contrast, rapamycin did not prevent the FSS-induced increase in Na(+)/K(+)-ATPase levels. Our data suggest that rapid tuning of the endocytic response by changes in FSS may contribute to glomerulotubular balance in vivo. Moreover, FSS provides an essential stimulus in the differentiation of PT cells via separate pathways that up-regulate endocytosis and ion transport capacity. Variations in FSS may also contribute to the maturation of PT cells during kidney development and during repair after kidney injury. CI - (c) 2017 Long et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution-Noncommercial-Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0). FAU - Long, Kimberly R AU - Long KR AD - Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Shipman, Katherine E AU - Shipman KE AD - Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Rbaibi, Youssef AU - Rbaibi Y AD - Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Menshikova, Elizabeth V AU - Menshikova EV AD - Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Ritov, Vladimir B AU - Ritov VB AD - Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Eshbach, Megan L AU - Eshbach ML AD - Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Jiang, Yu AU - Jiang Y AD - Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Jackson, Edwin K AU - Jackson EK AD - Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Baty, Catherine J AU - Baty CJ AD - Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. FAU - Weisz, Ora A AU - Weisz OA AD - Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261 weisz@pitt.edu. LA - eng GR - R01 DK101484/DK/NIDDK NIH HHS/United States GR - S10 OD021627/OD/NIH HHS/United States GR - P30 DK079307/DK/NIDDK NIH HHS/United States GR - T32 DK061296/DK/NIDDK NIH HHS/United States GR - R01 DK100357/DK/NIDDK NIH HHS/United States PT - Journal Article DEP - 20170718 PL - United States TA - Mol Biol Cell JT - Molecular biology of the cell JID - 9201390 RN - 0 (Membrane Proteins) RN - EC 2.7.11.1 (TOR Serine-Threonine Kinases) SB - IM MH - Animals MH - Cell Membrane/metabolism MH - Cells, Cultured MH - Endocytosis MH - Glomerular Filtration Rate MH - Kidney Tubules, Proximal/cytology/metabolism/*physiology MH - Membrane Proteins/physiology MH - Metabolic Networks and Pathways MH - Opossums MH - Protein Transport MH - Shear Strength MH - Stress, Mechanical MH - TOR Serine-Threonine Kinases/*metabolism PMC - PMC5597323 EDAT- 2017/07/20 06:00 MHDA- 2017/12/01 06:00 PMCR- 2017/11/30 CRDT- 2017/07/20 06:00 PHST- 2017/04/03 00:00 [received] PHST- 2017/07/07 00:00 [revised] PHST- 2017/07/13 00:00 [accepted] PHST- 2017/07/20 06:00 [pubmed] PHST- 2017/12/01 06:00 [medline] PHST- 2017/07/20 06:00 [entrez] PHST- 2017/11/30 00:00 [pmc-release] AID - mbc.E17-04-0211 [pii] AID - E17-04-0211 [pii] AID - 10.1091/mbc.E17-04-0211 [doi] PST - ppublish SO - Mol Biol Cell. 2017 Sep 15;28(19):2508-2517. doi: 10.1091/mbc.E17-04-0211. Epub 2017 Jul 18.