Cells lining the proximal tubule (PT) have unique membrane specializations that are required to maintain high-capacity ion transport and endocytic functions of this nephron segment. PT cells in vivo acutely regulate response changes glomerular filtration rate (GFR) glomerulotubular balance. culture up-regulate capacity acute fluid shear stress (FSS); however, it is not known whether GFR modulates endocytosis enable maximally efficient uptake filtered proteins vivo. Here, we show cultured...

Significance Statement Loss of function the 2Cl − /H + antiporter ClC-5 in Dent disease causes an unknown impairment endocytic traffic, leading to tubular proteinuria. The authors integrated data from biochemical and quantitative imaging studies proximal tubule cells into a mathematical model determine that loss impairs endosome acidification delays early maturation cells, resulting reduced megalin recycling, surface expression, half-life. Studies mouse also revealed subsegment-specific...

The kidney proximal tubule (PT) elaborates a uniquely high-capacity apical endocytic pathway to retrieve albumin and other proteins that escape the glomerular filtration barrier. Megalin cubilin/amnionless (CUBAM) receptors engage Dab2 in these cells mediate clathrin-dependent uptake of filtered ligands. Knockout megalin or profoundly inhibits endocytosis is believed atrophy pathway. We generated CRISPR/Cas9 knockout (KO) clones lacking cubilin, megalin, expression highly differentiated PT...

Abstract Megalin (Lrp2) is a multiligand receptor that drives endocytic flux in the kidney proximal tubule (PT) and necessary for recovery of albumin other filtered proteins escape glomerular filtration barrier. Studies our lab have shown knockout (KO) Lrp2 opossum PT cells leads to dramatic reduction sodium–glucose co-transporter 2 (SGLT2) transcript protein levels, as well differential expression genes involved mitochondrial metabolic function. SGLT2 levels are reduced more modestly KO...

Beyond glycemic control, SGLT2 inhibitors (SGLT2is) have protective effects on cardiorenal function. Renoprotection has been suggested to involve inhibition of NHE3 leading reduced ATP-dependent tubular workload and mitochondrial oxygen consumption. activity is also important for regulation endosomal pH, but the SGLT2i endocytosis are unknown. We used a highly differentiated cell culture model proximal tubule (PT) cells determine direct Na

Recent studies indicate that filtered albumin is retrieved in the proximal tubule (PT) via three pathways: receptor-mediated endocytosis cubilin (high affinity) and megalin (low affinity), fluid-phase uptake. Expression of required to maintain all pathways, making it challenging determine their respective contributions. Moreover, uptake molecules varies between sub-segments (S1, S2 S3) make up PT. Here we used new published data develop a mathematical model predicts rates mouse PT normal...

Abstract The cells that comprise the proximal tubule (PT) are specialized for high-capacity apical endocytosis necessary to maintain a protein-free urine. Filtered proteins reclaimed via receptor-mediated facilitated by multiligand receptors megalin and cubilin. Despite importance of this pathway, we lack detailed understanding trafficking kinetics how they regulated. Here, utilized biochemical quantitative imaging methods in highly differentiated model opossum kidney (OK) mouse vivo develop...

Significance Statement Patients with Lowe syndrome (LS) develop abnormalities in proximal tubule function that cause declining kidney function. Mutations the OCRL gene encoding LS. The enzyme encoded by hydrolyzes phosphatidylinositol 4,5-bisphosphate, a lipid regulates myriad cellular functions. authors created knockout model of human cells and observed loss impairs cell proliferation results accumulation multinucleated cells. Lrp2 -positive segments pronephric were shorter ocrl mutant...

Proximal tubule (PT) cells maintain a high-capacity apical endocytic pathway to recover essentially all proteins that escape the glomerular filtration barrier. The multiligand receptors megalin and cubilin play pivotal roles in uptake of normally filtered PT but also contribute nephrotoxic drugs, including aminoglycosides. We previously demonstrated opossum kidney (OK) cultured under continuous fluid shear stress (FSS) are superior static conditions recapitulating essential functional...

Acid transport is required for bone synthesis by osteoblasts. The osteoblast basolateral surface extrudes acid Na+/H+ exchange, but apical proton uptake undefined. We found high expression of the Cl−/H+ exchanger ClC3 at surface. In mammals functions in intracellular vesicular chloride transport, when we Cl− dependency H+ membranes, queried whether exchange formation. used knockout animals, and closely-related ClC5 animals: vitro studies suggested that both might support Genotypes were...

Proximal tubule (PT) cells maintain a high-capacity apical endocytic pathway to recover essentially all proteins that escape the glomerular filtration barrier. The multi ligand receptors megalin and cubilin play pivotal roles in uptake of normally filtered PT but also contribute nephrotoxic drugs, including aminoglycosides. We previously demonstrated opossum kidney (OK) cultured under continuous fluid shear stress (FSS) are superior static conditions recapitulating essential functional properties

Women are more protected from acute kidney injury, and chronic disease (CKD) in women progresses slowly to end-stage renal compared men. CKD involves changes the integrity of glomerular barrier function with consequent proteinuria. The proximal tubule (PT) normally reclaims albumin other filtered proteins via receptor-mediated endocytosis facilitated by multiligand receptors megalin cubilin. PT health, ultimately function, is impacted uptake excess nephrotoxic drugs that enter cells a...

Megalin ( Lrp2) is a multiligand receptor that drives endocytic flux in the kidney proximal tubule (PT) and necessary for recovery of albumin other filtered proteins escape glomerular filtration barrier. We previously found knocking out Lrp2 opossum (OK) PT cell line leads to differential expression genes involved mitochondrial metabolic function. Additionally, we observed large reductions sodium glucose co-transporter 2 (Sglt2) transcript (>80%) protein (~40%) levels. While Sglt2 levels...

Background: Beyond glycemic control, Sglt2 inhibitors (Sglt2i) have protective effects on renal function. Sglt2i-mediated reductions in Na + reabsorption been suggested to protect PT cells from damage. The mechanisms responsible for renoprotection are unknown and involve inhibition of NHE3 leading reduced ATP-dependent tubular workload mitochondrial oxygen consumption. activity is also important regulation endosomal pH, the Sglt2i endocytic function unknown. Aim this study: dissect direct...

The proximal tubule (PT) of the kidney is comprised cells that are uniquely specialized for efficient apical uptake albumin and other proteins escape glomerular filtration barrier. These bind to multiligand receptors megalin cubilin internalized via clathrin-dependent endocytosis into early endosomes rapidly mature larger vacuoles (AVs). Dissociated ligands delivered from AVs lysosomes degradation, while collected dense tubules recycling cell surface. When grown under continuous fluid shear...

The proximal tubule (PT) efficiently reclaims albumin and other proteins that escape the glomerular filtration barrier to maintain a protein free urine. recovery of filtered occurs via receptor-mediated endocytosis facilitated by multiligand receptors megalin cubilin. PT health is impacted excess uptake when breached nephrotoxic drugs enter cells in megalin/cubilin dependent manner. Understanding where how endocytic along axis key predicting disease outcomes devising strategies protect from...

Lackner, Emily; Shipman, Katherine E.; Cowan, Isabella; Long, Kimberly R.; Weisz, Ora A. Author Information

Lowe syndrome is an X‐linked recessive disorder caused by mutations in OCRL , which encodes the phosphatidylinositol 5′‐phosphatase OCRL1. Hallmark symptoms of include proximal tubule (PT) dysfunction, typically characterized low molecular weight proteinuria (LMWP), renal tubular acidosis, aminoaciduria, and hypercalciuria. OCRL1 has been hypothesized to play a role myriad cellular processes including membrane trafficking, actin dynamics, cell polarity, ciliogenesis, division. However,...

Epithelial cells that line the proximal tubule (PT) of kidney are responsible for reabsorption low molecular weight proteins and other small molecules from glomerular ultrafiltrate. A limitation in understanding regulation receptor mediated apical endocytosis filtered ligands has been lack a highly differentiated cell culture model tubule. Because PT vivo continually exposed to flow, we have cultured under continuous fluid shear stress (FSS) better recapitulate this environment. Opossum were...