Synthesis, cloning and primary structure of DNA complementary to mRNA for human pituitary pro-opiomelanocortin

cDNA coding for the human pro-opiomelanocortin (POMC) has been cloned and sequenced. It codes for full size amino acid sequence of POMC and furthermore, contains most part of the 3'-terminal noncoding mRNA region and 60 nucleotides coding for signal peptide.     

Cloning, primary structure determination and expression of preproinsulin cDNA from human insulinoma in Escherichia coli]

A human insulinoma cDNA library was constructed in expression plasmid vector pUEX1. Clone pUEX1Ins12 was selected from human insulinoma cDNA library by means of hybridization with the insulin probe and a nucleotide sequence of the insertion was determined. It codes for full size amino acid sequence preproinsulin and furthermore, contains the entire 3'-end of noncoding mRNA region and 44 nucleotides from the 5'-untranslated region. The bacterial strain pUEX3Ins8 producing preproinsulin as beta-galactosidase fusion protein was constructed.     

Species and organ differences in the activity and regulation of adenylate and guanylate cyclases

The activity of adenylate and guanylate cyclases was determined in adrenal, heart, liver and fat tissues of guinea pigs, mice, rabbits and monkeys. The enzymes activities varied markedly depending both on the species and organs. The highest basal activities of adenylate cyclase was observed in all organs of guinea pigs. It was found that organs with low basal level of adenylate cyclase possess high guanylate cyclase. Species variations of the basal and stimulated adenylate cyclase activity may determine the functional activity of an organ: the higher the adenylate cyclase activity, the more intensive steroidogenesis in adrenals, lipolysis in the fat tissue, muscle contraction and nerve impulse conduction in heart.     

Study of the Association between Constitutional Exogenous Obesity and Polymorphism of the Apolipoprotein B Gene

An attempt was made to associate the insertion–deletion (Ins/Del) polymorphism of the apolipoprotein B gene (apoB) with obesity and to identify alleles and genotypes predisposing to this disorder. The apoB Ins/Del allele frequencies observed in the Russian population were similar to those in West European populations and significantly differed from frequencies reported for Asian populations. Patients with obesity did not differ from healthy individuals in allele and genotype frequencies regardless of whether total or sex-stratified samples were compared. Estimation of relative risk for individuals with genotype Ins/Ins did not reveal a significant association between obesity and this genotype. Thus, constitutional exogenous obesity did not prove to be associated with the Ins/Del polymorphism of theapoB gene in the Russian population.     

Study of the association between constitutional exogenous obesity and polymorphism of the apolipoprotein B gene

An attempt was made to associate the insertion-deletion (Ins/Del) polymorphism of the apolipoprotein B gene (apoB) with obesity and to identify alleles and genotypes predisposing to this disorder. The apoB Ins/Del allele frequencies observed in the Russian population were similar to those in West European populations and significantly differed from frequencies reported for Asian populations. Patients with obesity did not differ from healthy individuals in allele and genotype frequencies regardless of whether total or sex-stratified samples were compared. Estimation of relative risk for individuals with genotype Ins/Ins did not reveal a significant association between obesity and this genotype. Thus, constitutional exogenous obesity did not prove to be associated with the Ins/Del polymorphism of the apoB gene in the Russian population.     

The role of periodic changes in cyclase and protein kinase activity in the mechanism of the proliferative effect of ACTH

A prolonged effect of ACTH on the state of adenylate and guanylate cyclase systems in the adrenal glands of experimental animals was investigated. It was found that in guinea pigs injected with ACTH (4 units daily for 1-50 days) the weight of adrenal glands and the DNA content in these organs increased 2.0-2.5-fold by the end of experiment; the increase in both values was stepwise. The corticosteroid level in the blood varied throughout the experiment: the changes in the DNA content in adrenals and in the corticosteroid content in the blood were oppositely directed. This was accompanied by cyclic changes in the basal and stimulated activities of adenylate and guanylate cyclases and proteinases in the adrenal glands occurring with a periodicity of 6-15 days. The activity peaks for cyclases and protein kinases preceded the rise in the DNA content in the adrenals. A clearcut correlation between the changes in the enzyme activity and the hormone dose was observed. The changes in the basal and stimulated activities of guanylate cyclase seem to be due to the control of cAMP level in the cell (stimulation of cGMP-dependent cAMP phosphodiesterase). Apparently, the periodic changes in the activity of cAMP-dependent protein kinases in the cytoplasmic and nuclear fractions and a relatively high activation of nuclear protein kinases (by 30-60%) in comparison of cytoplasmic ones (8-10%) are related to stimulation of DNA synthesis. It is concluded that the changes in the activity of cyclases and protein kinases play a role in the mechanism of proliferative effect of ACTH.     

A new mutation c.422C>G (p.S141C) in homoand heterozygous forms of the human leptin gene

Mutation g.15409C>G, n.422C>G (p.S141C) in homo-and heterozygous forms of the human LEP gene was identified among some patients of the high mountain village of Karaul, Ashkhabad oblast, Turkmenistan, some of which suffer from obesity. It causes the substitution S120C in the secreted leptin. The mature leptin molecule (146 aa) has only two Cys residues (96C and 146C) forming an S-S bridge, which is important for the hormone function. A third mutation, 120C, in the molecule might disturb the correct formation of the S-S bond and could alter the leptin activity.     

Adenylate cyclase and cAMP-dependent protein kinase activity in the adrenal glands of animals after chronic administration of ACTH

ACTH, a prolonged action hormone, in a dose of 2.5 mu. was injected into guinea pigs daily for 5-35 days. The adenylate cyclase activity of the crude adrenal membrane fraction and the activity of cAMP-dependent protein kinases in the cytoplasmic fraction were determined. Cyclic changes in the basal and stimulated adenylate cyclase activities occurring with 15-20-day intervals have been established for the first time. The sensitivity of adenylate cyclase to ACTH, NaF and GTP did not change in the course of two cycles. The activity of cAMP-dependent protein kinases increased during the first few days after ACTH administration and decreased after further injections of the hormone. The role of cyclic changes of the enzyme activity in the mechanism of proliferative effect of ACTH is discussed.