Low concentration of Triton X-100 inhibits diacylglycerol acyltransferase without measurable effect on phosphatidate phosphohydrolase in the human primordial placenta.
Agents causing accumulation of endogenous diacylglycerols (DAG) may be helpful in studies on the intracellular regulatory effects and on the mechanisms of attenuation of this putative second messenger. In a previous study (Tóth et al., BBA 921 (1987) 417-425) we have shown a marked stimulatory effect of low micellar concentration (0.05%, v/v) of Triton X-100 on the labelling of phosphatidic acid with (32P)phosphate in minced human primordial placenta. The present results demonstrate that 0.05% Triton X-100 inhibits nearly completely the conversion of (3H)diacylglycerols into (3H)triacylglycerols in placenta fragments incubated with (3H)glucose. However, this concentration of the detergent does not have any effect on the appearance of label in the sum of acylglycerols (comprising mono-, di- and triacylglycerols) and phosphatidylcholine, indicating a lack of effect on phosphatidate phosphohydrolase. The about 5-fold elevation of (3H)diacylglycerols was attended by an approximately 3-fold rise in (3H)phosphatidic acid and a 1.3-fold increase in the labelling of phosphatidylcholine. These findings provide supportive evidence that 1,2-DAG was formed due to inhibition of DAG-acyltransferase and suggest that some of the DAG was transformed into phosphatidic acid by diacylglycerol-kinase.
Gimes
G
G
2nd Department of Obstetrics and Gynecology, Semmelweis Medical University, Budapest, Hungary.
Tóth
M
M
D000217:Acyltransferases / Q000037:antagonists & inhibitors*; D051048:Diacylglycerol O-Acyltransferase; D004075:Diglycerides / Q000096:biosynthesis; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D017830:Octoxynol / Q000008:administration & dosage / Q000494:pharmacology*; D010711:Phosphatidate Phosphatase / Q000187:drug effects* / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis; D010920:Placenta / Q000187:drug effects* / Q000201:enzymology; D011247:Pregnancy; D014280:Triglycerides / Q000096:biosynthesis
D004075:Diglycerides; D010743:Phospholipids; D014280:Triglycerides; D017830:Octoxynol; D000217:Acyltransferases; D051048:Diacylglycerol O-Acyltransferase; D010711:Phosphatidate Phosphatase; D005947:Glucose