Document Detail

BAP31 and its caspase cleavage product regulate cell surface expression of tetraspanins and integrin-mediated cell survival.
MedLine Citation:
PMID:  15946936     Owner:  NLM     Status:  MEDLINE    
BAP31, a resident integral protein of the endoplasmic reticulum membrane, regulates the export of other integral membrane proteins to the downstream secretory pathway. Here we show that cell surface expression of the tetraspanins CD9 and CD81 is compromised in mouse cells from which the Bap31 gene has been deleted. CD9 and CD81 facilitate the function of multiprotein complexes at the plasma membrane, including integrins. Of note, BAP31 does not appear to influence the egress of alpha5beta1 or alpha(v)beta3 integrins to the cell surface, but in Bap31-null mouse cells, these integrins are not able to maintain cellular adhesion to the extracellular matrix in the presence of reduced serum. Consequently, Bap31-null cells are sensitive to serum starvation-induced apoptosis. Reconstitution of wild-type BAP31 into these Bap31-null cells restores integrin-mediated cell attachment and cell survival after serum stress, whereas interference with the functions of CD9, alpha5beta1, or alpha(v)beta3 by antagonizing antibodies makes BAP31 cells act similar to Bap31-null cells in these respects. Finally, in human KB epithelial cells protected from apoptosis by BCL-2, the caspase-8 cleavage product, p20 BAP31, inhibits egress of tetraspanin and integrin-mediated cell attachment. Thus, p20 BAP31 can operate upstream of BCL-2 in living cells to influence cell surface properties due to its effects on protein egress from the endoplasmic reticulum.
Marina Stojanovic; Marc Germain; Mai Nguyen; Gordon C Shore
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-06-09
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  280     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-08-22     Completed Date:  2005-10-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  30018-24     Citation Subset:  IM    
Department of Biochemistry, McIntyre Medical Sciences Building, McGill University, Montreal, Quebec H3G 1Y6, Canada.
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MeSH Terms
Antigens, CD / biosynthesis
Caspase 8
Caspases / metabolism
Cell Adhesion
Cell Membrane / metabolism
Cell Separation
Cell Survival
Endoplasmic Reticulum / metabolism
Epithelial Cells / cytology
Extracellular Matrix / metabolism
Fibronectins / metabolism
Flow Cytometry
Gene Deletion
Integrin alpha5beta1 / metabolism
Integrin alphaVbeta3 / metabolism
Integrins / metabolism*
Intracellular Membranes / metabolism
Membrane Glycoproteins / biosynthesis
Membrane Proteins / biosynthesis*,  chemistry,  physiology
Mice, Inbred C57BL
Microscopy, Fluorescence
Protein Structure, Tertiary
Proto-Oncogene Proteins c-bcl-2 / metabolism
Time Factors
Reg. No./Substance:
0/Antigens, CD; 0/Bcap31 protein, mouse; 0/CD81 antigen; 0/CD9 antigen; 0/Fibronectins; 0/Integrin alpha5beta1; 0/Integrin alphaVbeta3; 0/Integrins; 0/Membrane Glycoproteins; 0/Membrane Proteins; 0/Proto-Oncogene Proteins c-bcl-2; EC 3.4.22.-/CASP8 protein, human; EC 3.4.22.-/Casp8 protein, mouse; EC 3.4.22.-/Caspase 8; EC 3.4.22.-/Caspases

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