Book of Abstracts: Albany 2005
Alteration in Content of Chromatin Phospholipids Under the Action of Hydrocortisone and Insulin
The progress in lipidology for the last two decades demonstrated that different fractions of lipids (especially phospholipids) are actively involved in the chromatin structure and play an important role in its structural and functional organization.
The results showed changes in quantity of total phospholipids as well as in content of their individual fractions in chromatin of liver cells under the actions of hormones. The increase of phospholipids quantity was observed both in case of hydrocortisone and insulin action (1.35 and 1.20 fold respectively). This increase was also detected in active fraction of chromatin while in non active chromatin the in vivo action of both hormones didn?t cause any changes in phospholipids content. The same-directed alterations in total phospholipids under the action of hormones was accompanied by deferent changes of separate fractions of phospholipids. Particularly, hormones lead various changes in content of polyphosphoinositides and sphingomyelines.
Hydrocortisone action increases the content of monophosphoinositides and decreases that of triphosphoinositides while the action of insulin is vice versa in both total and active fractions of chromatin. These changes are conformable with those of other nuclear structures such as nuclear membranes and nuclear matrix that indicate the universal character of hormonal control of phospholipids metabolism in whole nuclei. The quantity of sphingomyelines was increased in chromatin and its active fraction after the in vivo action of both hormones. The obtained results were discussed from point of view of important role of these lipids in regulation of transcription activity by hormones of different nature.
Emil S. Gevorgyan*
Yerevan State University