Clarification of mechanism of cell degeneration using Drosophila and mouse mutant

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1. To check whether the product of rdgA (retinal degeneration A) gene of Drosophila is diacylglycerol (DG) kinase, I have adopted a biochemical approach by attempting to purify the DG kinase of Drosophila. DG kinase was extracted from normal fly heads, and purified by sequential column chromatography. The purification achieved was not complete because of the small amount of the enzyme in Drosophila heads and its low yield through the purification procedures, but a 115 kd protein correlated with the enzyme activity. Although a 115 kd protein was separated with two dimensional electrophoresis and extracted from the gel, amount of the protein was not sufficient to determine its amino acid sequences.2. Inositol phospholipid metabolism in cerebellum degenerated mouse and rat was examined by imunofluorescent staining. Phosphatidylinositol bisphosphate (PIP_2) was detecteted in granule cells of pcd (Purkinje cell degeneration) mutant mouse cerebellum but inositol trisphosphate binding protein and type I protein kinase C (PKC) were not. The staining of PIP_2 in cerebellum degenerated rat by drugs was similar to that in normal.3. When phosphatidylinositol (PI) liposomes were introduced into culture media, viability of c-myc unexpressed human renal cancer cells were reduced, while that of c-myc expressed cells was not. Death of c-myc unexpressed ells by PI liposomes was found to be caused by abnormally accumulated intracellular Ca^2. PI liposome treatment caused decrease of PKC activity in all cells examined, and reduction of activity of particulate fraction was significant in c-myc unexpressed cells.