Hormonal regulation of focal adhesions in bovine adrenocortical cells: induction of paxillin dephosphorylation by adrenocorticotropic hormone.
A study of bovine adrenocortical cell shape on adrenocorticotropic hormone (ACTH) challenge showed that the cells round up and develop arborized processes. This effect was found to be (1) specific for ACTH because angiotensin II and basic fibroblast growth factor have no effect; (2) mediated by a cAMP-dependent pathway because forskolin reproduces the effect of the hormone; (3) inhibited by sodium orthovanadate, a phosphotyrosine phosphatase inhibitor, but unchanged by okadaic acid, a serine/threonine phosphatase inhibitor; and (4) correlated with a complete loss of focal adhesions. Biochemical studies of the focal-adhesion-associated proteins showed that pp125fak, vinculin (110 kDa) and paxillin (70 kDa) were detected in the Triton X-100-insoluble fraction from adrenocortical cells. During cell adhesion on fibronectin as substratum, two major phosphotyrosine-containing proteins of molecular masses 125 and 68 kDa were immunodetected in the same fraction. A dramatic decrease in the extent of tyrosine phosphorylation of these proteins was observed within 60 min after treatment with ACTH. No change in pp125fak tyrosine phosphorylation nor in Src activity was detected. In contrast, paxillin was found to be tyrosine-dephosphorylated in a time-dependent manner in ACTH-treated cells. Sodium orthovanadate completely prevented the effect of ACTH. These observations suggest a possible role for phosphotyrosine phosphatases in hormone-dependent cellular regulatory processes.
Vilgrain
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I
Unité INSERM 244, Biochimie des Régulations Cellulaires Endocrines, Département de Biologie Moléculaire et Structurale, CEA, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France. i.vilgrain@goleon.ceng.cea.fr
Chinn
A
A
Gaillard
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I
Chambaz
E M
EM
Feige
J J
JJ
D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D002417:Cattle; D015815:Cell Adhesion Molecules / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007150:Immunohistochemistry; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000032:analysis; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology; D019061:src-Family Kinases
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D051419:Paxillin; D010750:Phosphoproteins; D005576:Colforsin; D019000:Phosphotyrosine; D014638:Vanadates; D014443:Tyrosine; D000324:Adrenocorticotropic Hormone; D000242:Cyclic AMP; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019061:src-Family Kinases; D017027:Protein Tyrosine Phosphatases