Specific protein kinase C isoforms are required for rod photoreceptor differentiation.

The protein kinase C family of enzymes regulates cell physiology through phosphorylation of serine and threonine residues of many proteins in most cell types. Here we identify and as isoforms that are essential for rod photoreceptor differentiation in mouse retinas. Using ex vivo retinal explants, we found that phorbol ester 12-myristate 13-acetate and insulin-like growth factor 1 (IGF1) induced rod differentiation, as defined by opsin or Crx expression, in a manner days ahead of rod development in untreated explants. duanyu1531-β1 and duanyu1531-γ were colocalized with proliferating cell nuclear antigen (PCNA)- and progenitors through the later differentiation period. Pharmacological or genetic inhibition of either isoform resulted in a partial reduction in the appearance of rods, whereas removing both isoforms resulted in their complete absence. Furthermore, a significant decline of tyrosine phosphorylation was observed by activation of while inhibition of resulted in an increase of phosphorylated duanyu18133 along with a delayed cell cycle exit of progenitors with prolonged PCNA expression. In adult retinas, IGF1 activates PI-3 kinase (PI3K), but in neonatal retinas its action is identical to the action of an PI3K inhibitor. These data unveil a novel signaling cascade that coordinates and regulates rod differentiation through specific duanyu1531 isoforms in mammals.

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