A5026814916- Cellular transport and secretion
- Biomedical Research and Pathophysiology
- Erythrocyte Function and Pathophysiology
- Chronic Kidney Disease and Diabetes
- Pancreatic function and diabetes
- Lipid Membrane Structure and Behavior
- Renal Diseases and Glomerulopathies
- Glycosylation and Glycoproteins Research
- Renal and related cancers
- Genetic and Kidney Cyst Diseases
- Ion Transport and Channel Regulation
- Ion channel regulation and function
- Calcium signaling and nucleotide metabolism
- Retinal Development and Disorders
- Galectins and Cancer Biology
- Lysosomal Storage Disorders Research
- Virus-based gene therapy research
- HIV Research and Treatment
- Adenosine and Purinergic Signaling
- Diabetes Treatment and Management
- Endoplasmic Reticulum Stress and Disease
- Hemoglobinopathies and Related Disorders
- Photoreceptor and optogenetics research
- RNA Interference and Gene Delivery
- Pineapple and bromelain studies
University of Pittsburgh
2015-2024
RELX Group (United States)
2018-2019
Renal Association
2007-2014
Mount Sinai Hospital
2000-2002
Johns Hopkins Medicine
1987-2000
Johns Hopkins University
1987-2000
In striated muscle, the plasma membrane forms tubular invaginations (transverse tubules or T-tubules) that function in depolarization-contraction coupling. Caveolin-3 and amphiphysin were implicated their biogenesis. Amphiphysin isoforms have a putative role deformation at endocytic sites. An isoform of 2 concentrated T-tubules induced when expressed nonmuscle cells. This property required exon 10, phosphoinositide-binding module. developing myotubes, caveolin-3 segregated vesicular portions...
Epithelial sodium channels (ENaC) are expressed in the apical membrane of high resistance Na+ transporting epithelia and have a key role regulating extracellular fluid volume airway surface liquids. Maturation activation ENaC subunits involves furin-dependent cleavage ectodomain at two sites α subunit single site within γ subunit. We now report that serine protease prostasin further activates by inducing distal to furin site. Dual is predicted release 43-amino acid peptide. Channels with...
The kidney has an extraordinary ability to maintain stable fractional solute and fluid reabsorption over a wide range of glomerular filtration rates (GFRs). Internalization filtered low molecular weight proteins, vitamins, hormones, other small molecules is mediated by the proximal tubule (PT) multiligand receptors megalin cubilin. Changes in GFR accompanying shear stress (FSS) modulate acute changes PT ion transport thought be microvillar bending. We found that FSS also affects apical...
Hypertension and kidney disease have been repeatedly associated with genomic variants alterations of lysine metabolism. Here, we combined stable isotope labeling untargeted metabolomics to investigate lysine's metabolic fate in vivo. Dietary 13C6 labeled was tracked metabolites across various organs. Globally, reacts rapidly molecules the central carbon metabolism, but incorporates slowly into proteins acylcarnitines. Lysine metabolism is accelerated a rat model hypertension damage, chiefly...
MUC1 is a mucin-like type 1 transmembrane protein associated with the apical surface of epithelial cells. In human tumors origin overexpressed in an underglycosylated form truncated O-glycans and accumulates intracellular compartments. To understand basis for this altered subcellular localization, we compared synthesis trafficking various glycosylated forms normal (Chinese hamster ovary) cells glycosylation-defective (ldlD) that lack epimerase to make UDP-Gal/GalNAc from UDP-Glc/GlcNAc....
The vesicular stomatitis virus (VSV) G protein is a model transmembrane glycoprotein that has been extensively used to study the exocytotic pathway. A signal in cytoplasmic tail of VSV (DxE or Asp-x-Glu, where x any amino acid) was recently proposed mediate efficient export from endoplasmic reticulum (ER). In this study, we show DxE motif only partially accounts for ER exit G. We have identified six-amino-acid signal, which includes previously Asp and Glu residues, required ER. This...
Phosphatidylinositol 4-phosphate (PI4P) regulates biosynthetic membrane traffic at multiple steps and differentially affects the surface delivery of apically basolaterally destined proteins in polarized cells. Two phosphatidylinositol 4-kinases (PI4Ks) have been localized to Golgi complex mammalian cells, type III PI4Kbeta (PI4KIIIbeta) II PI4Kalpha (PI4KIIalpha). Here we report that PI4KIIIbeta PI4KIIalpha localize discrete subcompartments Madin-Darby canine kidney (MDCK) was enriched early...
Three derivatives of a triantennary glycopeptide, each containing single uniquely located 6-amino-galactose residue at either position 6', 6, or 8, were modified the 6-amino group by attachment photolyzable reagent and radiolabeled iodination tyrosine. These allowed to bind asialoglycoprotein receptor isolated rat hepatocytes photolyzed for affinity labeling. (formula; see text) Each probe specifically labeled major (RHL1) minor (RHL2/3) subunits which comprise receptor. A attached galactose...
The octameric exocyst complex is associated with the junctional and recycling endosomes proposed to selectively tether cargo vesicles directed toward basolateral surface of polarized Madin-Darby canine kidney (MDCK) cells. We observed that subunits Sec6, Sec8, Exo70 were localized early endosomes, transferrin-positive common Rab11a-positive apical MDCK Consistent its localization multiple populations addition function-blocking Sec8 antibodies streptolysin-O-permeabilized cells revealed...
In many epithelial tissues in the body (e.g. kidney distal nephron, colon, airways) rate of Na+ reabsorption is governed by activity channel (ENaC). ENaC turn regulated a number factors including hormones, physiological conditions, and other ion channels. To begin to understand mechanisms which regulated, we have examined trafficking turnover subunits A6 cells, polarized, hormonally responsive Xenopus cell line. As previously observed others, half-life newly synthesized was universally short...
The lysosomal storage disorder mucolipidosis type IV (MLIV) is caused by mutations in the transient receptor potential–mucolipin-1 (TRP-ML1) ion channel. “biogenesis” model for MLIV pathogenesis suggests that TRP-ML1 modulates postendocytic delivery to lysosomes regulating interactions between late endosomes and lysosomes. This based on observed lipid trafficking delays patient fibroblasts. Because membrane traffic aberrations may be secondary buildup chronically TRP-ML1–deficient cells, we...
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...
Proximal tubule (PT) cells express a single saturable albumin-binding site whose affinity matches the estimated tubular concentration of albumin; however, albumin uptake capacity is greatly increased under nephrotic conditions. Deciphering individual contributions megalin and cubilin to normal levels impossible in vivo, as knockout mice globally disrupts PT endocytic uptake. We quantified concentration-dependent an optimized opossum kidney cell culture model fit kinetic profiles identify...
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...