Enhanced expression of the cytoskeleton-associated proteins paxillin and focal adhesion kinase in glomerular immune injury.
In a rat model of glomerular immune injury induced by antibody against the glomerular basement membrane (GBM), we assessed changes in the levels and in the extent of tyrosine phosphorylation of two cytoskeleton-associated proteins, focal adhesion kinase (FAK) and paxillin. Glomeruli were isolated 2, 7, and 14 days after the administration of a rabbit anti-rat GBM antibody that induced proliferative nephritis and proteinuria. FAK and paxillin levels in glomerular protein lysates were assessed by immunoprecipitation followed by Western blot analysis. Changes in the tyrosine phosphorylation of immunoprecipitated paxillin and FAK were assessed by Western blot analysis with antiphosphotyrosine antibodies. Glomerular levels of FAK and paxillin were increased in nephritic glomeruli as compared with non-nephritic controls at all time points. There was a discordant increase in the tyrosine phosphorylation levels of paxillin and FAK; the increase in the tyrosine phosphorylation of FAK was sustained and peaked on day 7 of immune injury, whereas that of paxillin was short-lived and peaked on day 2 of injury. We propose that these changes in FAK and paxillin expression and tyrosine phosphorylation reflect interactions between glomerular cells and accumulating extracellular matrix proteins in the course of immune injury, or they constitute parts of wider signaling events within the nephritic glomerulus that involve the cytoskeleton.
Koukouritaki
S B
SB
Cardiovascular Research Center-Nephrology, Medical College of Wisconsin, Milwaukee, USA.
Tamizuddin
A
A
Lianos
E A
EA
D000818:Animals; D019867:Anti-Glomerular Basement Membrane Disease / Q000276:immunology / Q000378:metabolism*; D000906:Antibodies / Q000494:pharmacology; D001323:Autoantibodies / Q000276:immunology; D001485:Basement Membrane / Q000737:chemistry / Q000201:enzymology / Q000276:immunology; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000096:biosynthesis*; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000096:biosynthesis*; D003599:Cytoskeleton / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007114:Immunization; D007074:Immunoglobulin G / Q000494:pharmacology; D007678:Kidney Glomerulus / Q000737:chemistry / Q000201:enzymology* / Q000276:immunology; D008297:Male; D051419:Paxillin; D010750:Phosphoproteins / Q000032:analysis / Q000096:biosynthesis*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000096:biosynthesis*; D011817:Rabbits; D051381:Rats; D011917:Rats, Inbred Lew; D014443:Tyrosine / Q000378:metabolism
D000906:Antibodies; D001323:Autoantibodies; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D007074:Immunoglobulin G; D051419:Paxillin; D010750:Phosphoproteins; C496063:Pxn protein, rat; C051951:antiglomerular basement membrane antibody; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat