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S Sato, Y Katagiri, K Goto, H Yamashita; Expression patterns of Diacylglycerol Kinase(DGK) isozymes in Normal Rat Retina . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3617.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Diacylglycerol kinase (DGK) phosphorylates diacylglycerol (DAG)(a very important signal transducer in cytoplasm) to degrade into phosphatidic acid (PA), so is one of the key enzymes by regulating DAG level in the intracytoplasmic signal transduction. DGK regulates signals mediated by inositol-phospholipid turnover and activates protein kinase C (PKC) which is involved in the signal transduction from various growth factors. The critical importance of DGK in the visual function has been demonstrated by the report that retinal degeneration occurs in the rdgA mutant mice with the mutation of mouse DGK correponding to rat DGKϵ. The phosphoinositide cycle is suggested to be involved in the phototransduction in retina of invertebrate eyes. The function in the vertebrate eyes is suggested to be different, which remains to be clarified. At present 6 isozymes of DGK (α,ß,γ,ζ,ι,ϵ) have been cloned. We observed the expression patterns of DGK isozymes in normal rat retina to investigate the function in the vertebrate retina. Methods:The retinas were obtained from 8 adult normal Wistar rats. The expression of DGK isozymes was observed at mRNA level (Northern blotting) and at protein level (immunohistochemical observation). The brain was used as a positive control. The probes for Northern blotting were constructed from the sequence outside the highly conserved catalytic domain to avoid the cross-reactivity. Results:Five DGK isozymes (α,ß,ζ,ι,ϵ) were detected in the normal rat retina, and DGKγ was not detected. The estimated sizes of mRNA's of the DGK isozymes in the rat retina were similar to those in the rat brain. Among 5 isozymes, the expression levels of DGKι and ϵ were high, and that of DGKα was very low in the retina. Conclusion:Five DGK isozymes were expressed in normal rat retina, and are suggested to play certain roles in the normal retinal functions.
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