Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies from our laboratory have shown that messenger RNAs (mRNAs) coding for a cAMP-specific phosphodiesterase (PDE4A) are present in mature rat and mouse germ cells. However, no information is available about the properties of the expressed proteins. To determine their structure and regulation, the PDE4A isoforms expressed in the rat testis were identified and compared to the variants expressed in the brain. Western blot analysis using an antiserum specific for PDE4A demonstrated the presence in testis extracts of two distinct proteins with apparent masses of 98.8 and 86 kDa. The electrophoretic mobilities of these proteins differ from those of proteins detected in the brain extracts (113 and 76 kDa). Reverse transcriptase-PCR of the different splicing mRNA variants expressed in testis confirmed the presence of at least one novel PDE4A mRNA that is distinct from the PDE4A splicing variants identified in the brain and other tissues. Expression of the complementary DNA encoding this variant in a heterologous system resulted in an increase in PDE activity and the appearance of an immunoreactive protein with a mass of 98.8 kDa. No 86-kDa protein could be generated with this transfection. Upon fractionation of testis extracts by HPLC diethylaminoethyl-chromatography, a peak of cAMP-PDE activity coeluted with the two immunoreactive species. During testicular development, the 98.8-kDa protein is present in trace amounts at 10 days, and its level increases with the age of the animals, reaching a plateau at 40 days. The 86-kDa protein appears at 20 days of age and reaches its maximum at 40 days. Studies on the cellular site of expression demonstrated that the two polypeptides are most abundant in round spermatids and are expressed in trace amounts in pachytene spermatocytes, whereas they could not be detected in Sertoli or interstitial cells. The 98.8-kDa, but not the 86-kDa, protein was also expressed in epididymal spermatozoa. These data demonstrate the expression of novel cAMP-specific PDEs coded by the PDE4A gene. The expression of these isoforms is maximal in round spermatids and is maintained in mature spermatozoa. The genesis of the lower mol wt species remains to be determined.
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PMID:Developmental regulation of unique adenosine 3',5'-monophosphate-specific phosphodiesterase variants during rat spermatogenesis. 864 Dec

In vivo effects of milrinone, a selective phosphodiesterase 3 (PDE-3) inhibitor, on plasma free fatty acids (FFA), glucose, and insulin levels were examined in alert rats. In dose response studies, intravenous injection of 1, 5 or 25 micromol/kg of milrinone provoked an immediate increase in plasma concentrations of FFA and insulin, while glucose levels rose only in response to the 5- and 25-micromol/kg doses. During euglycemic-hyperinsulinemic (approximately 450 pmol/L) clamps, intravenous injection of milrinone (25 micromol/kg) completely inhibited insulin suppression of lipolysis and of endogenous glucose production, while having no effect on insulin-stimulated glucose uptake (ISGU). To explore the reason why ISGU was not affected, we performed reverse-transcriptase polymerase chain reaction (RT-PCR) with RNA from skeletal muscle, fat, and liver. The results showed that PDE-3B mRNA was expressed in adipose tissue and liver, but it was not detected in skeletal muscle. We conclude that PDE-3 plays a major role in the inhibitory action of insulin on lipolysis in fat and on glucose production in liver and, in addition, seems to be involved in insulin secretion in pancreatic beta cells.
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PMID:Milrinone, a selective phosphodiesterase 3 inhibitor, stimulates lipolysis, endogenous glucose production, and insulin secretion. 1462 13

Cyclic nucleotide PDEs (phosphodiesterases) are important enzymes that regulate intracellular levels of cAMP and cGMP. In the present study, we identify and characterize novel PDEs in the genetic model, Drosophila melanogaster. The Drosophila genome encodes five novel PDE genes in addition to dunce. Predicted PDE sequences of Drosophila show highly conserved critical domains when compared with human PDEs. Thus PDE-encoding genes of D. melanogaster are CG14940-PDE1C, CG8279-PDE6beta, CG5411-PDE8A, CG32648-PDE9 and CG10231-PDE11. Reverse transcriptase-PCRs of adult tissues reveal widespread expression of PDE genes. Drosophila Malpighian (renal) tubules express all the six PDEs: Drosophila PDE1, dunce (PDE4), PDE6, PDE8, PDE9 and PDE11. Antipeptide antibodies were raised against PDE1, PDE6, PDE9 and PDE11. Verification of antibody specificity by Western blotting of cloned and expressed PDE constructs allowed the immunoprecipitation studies of adult Drosophila lysates. Biochemical characterization of immunoprecipitated endogenous PDEs showed that PDE1 is a dual-specificity PDE (Michaelis constant Km for cGMP: 15.3+/-1 microM; Km cAMP: 20.5+/-1.5 microM), PDE6 is a cGMP-specific PDE (Km cGMP: 37+/-13 microM) and PDE11 is a dual-specificity PDE (Km cGMP: 6+/-2 microM; Km cAMP: 18.5+/-5.5 microM). Drosophila PDE1, PDE6 and PDE11 display sensitivity to vertebrate PDE inhibitors, zaprinast (IC50 was 71+/-39 microM for PDE1, 0.65+/-0.015 microM for PDE6 and 1.6+/-0.5 microM for PDE11) and sildenafil (IC50 was 1.3+/-0.9 microM for PDE1, 0.025+/-0.005 microM for PDE6 and 0.12+/-0.06 microM for PDE11). We provide the first characterization of a cGMP-specific PDE and two dual-specificity PDEs in Drosophila, and show a high degree of similarity in structure and function between human and Drosophila PDEs.
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PMID:Cyclic nucleotide phosphodiesterases in Drosophila melanogaster. 1567 86