Phospholipase C-gamma1 is required for calcium-induced keratinocyte differentiation.
Phospholipase C-gamma1 is the most abundant member of the phospholipase C family in keratinocytes and is induced by calcium. Phospholipase C-gamma1, therefore, may be involved in the signal transduction system leading to calcium regulation of keratinocyte differentiation. To test this hypothesis, expression of phospholipase C-gamma1 in human keratinocytes was blocked by transfecting cells with the antisense human phospholipase C-gamma1 cDNA construct. These cells demonstrated a dramatic reduction in phospholipase C-gamma1 protein level compared with the empty vector-transfected cells and a marked reduction in the mRNA and protein levels of the differentiation markers involucrin and transglutaminase following administration of calcium. Similarly, cotransfection of antisense phospholipase C-gamma1 constructs with a luciferase reporter vector containing involucrin or transglutaminase promoters led to a substantial reduction in calcium-stimulated involucrin and transglutaminase promoter activities. Similar results were seen following treatment with a specific phospholipase C inhibitor U73122. To determine whether phospholipase C-gamma1 regulated differentiation by controlling intracellular calcium, we examined the ability of antisense phospholipase C-gamma1 to block the calcium-induced rise in intracellular calcium and found that it could. These findings indicate that phospholipase C-gamma1 is a critical component of the signaling pathway mediating calcium regulation of keratinocyte differentiation via its mobilization of intracellular calcium.
Xie
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Z
Endocrine Unit, Veterans Affairs Medical Center, University of California, San Francisco, California 94121, USA. zjxie@itsa.ucsf.edu
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D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D016373:DNA, Antisense / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D015603:Keratinocytes / Q000201:enzymology / Q000378:metabolism*; D051966:Phospholipase C gamma; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism*
D016373:DNA, Antisense; D007527:Isoenzymes; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D002118:Calcium