ACTH-induced caveolin-1 tyrosine phosphorylation is related to podosome assembly in Y1 adrenal cells.
Y1 adrenocortical cells respond to ACTH with a characteristic rounding-up that facilitates cAMP signaling, critical for transport of cholesterol to the mitochondria and increase in steroid secretion. We here demonstrate that caveolin-1 participates in coupling activation of protein kinase A (PKA) to the control of cell shape. ACTH/8-Br-cAMP induced reorganization of caveolin-1-positive structures in correlation with the cellular rounding-up. Concomitant with this change, there was an increase in the phosphorylation of caveolin-1 (Tyr-14) localized at focal adhesions (FA) with reorganization of FA to rounded, ringlike structures. Colocalization with phalloidin showed that phosphocaveolin is present at the edge of actin filaments and that after ACTH stimulation F-actin dots at the cell periphery become surrounded by phosphocaveolin-1. These observations along with electron microscopy studies revealed these structures as podosomes. Podosome assembly was dependent on both PKA and tyrosine kinase activities because their formation was impaired after treatment with specific inhibitors [myristoylated PKI (mPKI) or PP2, respectively] previous to ACTH/8-Br-cAMP stimulation. These results show for the first time that ACTH induces caveolin-1 phosphorylation and podosome assembly in Y1 cells and support the view that the morphological and functional responses to PKA activation in steroidogenic cells are related to cytoskeleton dynamics.
Colonna
Cecilia
C
Departamento de Bioquímica Humana, Facultad de Medicina, Universidad de Buenos Aires, C1121ABG Buenos Aires, Argentina. ccolonna@fmed.uba.ar
Podestá
Ernesto J
EJ
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000199:Actins / Q000378:metabolism / Q000648:ultrastructure; D000302:Adrenal Cortex / Q000187:drug effects / Q000378:metabolism*; D000305:Adrenal Cortex Hormones / Q000096:biosynthesis / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D051242:Caveolin 1; D022461:Caveolins / Q000187:drug effects / Q000378:metabolism*; D048430:Cell Shape / Q000187:drug effects / Q000502:physiology; D022081:Cell Surface Extensions / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D008954:Models, Biological; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000199:Actins; D000305:Adrenal Cortex Hormones; C495541:Cav1 protein, mouse; D051242:Caveolin 1; D022461:Caveolins; D004791:Enzyme Inhibitors; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000324:Adrenocorticotropic Hormone; D011505:Protein-Tyrosine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases