Document Detail


OCRL1 function in renal epithelial membrane traffic.
MedLine Citation:
PMID:  19940034     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The X-linked disorder Lowe syndrome arises from mutations in OCRL1, a lipid phosphatase that hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP(2)). Most patients with Lowe syndrome develop proteinuria very early in life. PIP(2) dynamics are known to modulate numerous steps in membrane trafficking, and it has been proposed that OCRL1 activity regulates the biogenesis or trafficking of the multiligand receptor megalin. To examine this possibility, we investigated the effects of siRNA-mediated OCRL1 knockdown on biosynthetic and postendocytic membrane traffic in canine and human renal epithelial cells. Cells depleted of OCRL1 did not have significantly elevated levels of cellular PIP(2) but displayed an increase in actin comets, as previously observed in cultured cells derived from Lowe patients. Using assays to independently quantitate the endocytic trafficking of megalin and of megalin ligands, we could observe no defect in the trafficking or function of megalin upon OCRL1 knockdown. Moreover, apical delivery of a newly synthesized marker protein was unaffected. OCRL1 knockdown did result in a significant increase in secretion of the lysosomal hydrolase cathepsin D, consistent with a role for OCRL1 in membrane trafficking between the trans-Golgi network and endosomes. Together, our studies suggest that OCRL1 does not directly modulate endocytosis or postendocytic membrane traffic and that the renal manifestations observed in Lowe syndrome patients are downstream consequences of the loss of OCRL1 function.
Authors:
Shanshan Cui; Christopher J Guerriero; Christina M Szalinski; Carol L Kinlough; Rebecca P Hughey; Ora A Weisz
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2009-11-25
Journal Detail:
Title:  American journal of physiology. Renal physiology     Volume:  298     ISSN:  1522-1466     ISO Abbreviation:  Am. J. Physiol. Renal Physiol.     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-27     Completed Date:  2010-03-09     Revised Date:  2011-07-22    
Medline Journal Info:
Nlm Unique ID:  100901990     Medline TA:  Am J Physiol Renal Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  F335-45     Citation Subset:  IM    
Affiliation:
Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania 15261, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cell Line
Dogs
Endocytosis / drug effects
Epithelium / metabolism
Gene Transfer Techniques
Hemagglutinin Glycoproteins, Influenza Virus / biosynthesis,  genetics
Humans
Hydrolases / metabolism
Kidney / metabolism*
Kinetics
LDL-Receptor Related Protein 2 / metabolism*
Lysosomes / enzymology
Molecular Weight
Phosphoric Monoester Hydrolases / genetics,  metabolism*
Protein Transport / drug effects
Proteins / chemistry,  metabolism
RNA, Small Interfering / pharmacology
Grant Support
ID/Acronym/Agency:
DK-054787/DK/NIDDK NIH HHS; DK-064613/DK/NIDDK NIH HHS; P30 DK079307/DK/NIDDK NIH HHS; T32 DK-061296/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Hemagglutinin Glycoproteins, Influenza Virus; 0/LDL-Receptor Related Protein 2; 0/Proteins; 0/RNA, Small Interfering; EC 3.-/Hydrolases; EC 3.1.3.-/Phosphoric Monoester Hydrolases; EC 3.1.3.36/OCRL protein, human
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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