Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oral treatment with 0.4 mg/kg/day of tamoxifen citrate, an antiestrogen, has been reported to reduce the fertility of adult male rat, presumably through estrogen receptors expressed throughout the male reproductive tract. During the course of these studies, tamoxifen was observed to gradually alter the pattern of sperm motility in the cauda epididymides without reducing sperm counts. Studies were carried out to understand the mechanism involved in tamoxifen induced change in the sperm motility pattern. In order to study the direct effects of tamoxifen on motility, biochemical levels/activities of sperm calcium, cAMP, phosphodiesterase and dynein ATPase, normally implicated in sperm motility were studied In view of the fact that tamoxifen is a ligand of estrogen receptor, estrogen receptor alpha protein and transcript were localized on rat sperm membrane and the effect of tamoxifen studied. The present study demonstrated presence of estrogen receptor protein and mRNA in the rat sperm by immunofluorescence, western blotting and in situ hybridization respectively. Specificity of sperm estrogen receptors was confirmed by conventional binding studies using [3H]-estradiol. There was no effect of tamoxifen treatment on estrogen receptors in rat sperms. Biochemical analysis of the sperms from tamoxifen treated cauda epididymides revealed a significant increase in the levels of calcium and cAMP. A significant reduction was also apparent in the activity of dynein ATPase. Tamoxifen treatment did not alter phosphodiesterase activity. Estrogen receptors could be identified both in the control as well as tamoxifen treated rat sperms. It was concluded that tamoxifen treatment mobilized calcium from the intra- or extra-cellular pools with a concomitant increase in cAMP and presumably activation of PKA (protein kinase A). Tamoxifen altered the pattern of sperm motility through a calcium induced block in the activity of dynein ATPase, presumably through the activation of sperm phosphatase. The putative estrogen receptor mediated signal transduction pathway appears to be directly affected in the tamoxifen treated, sub-motile rat sperm.
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PMID:Estrogen receptor, calcium mobilization and rat sperm motility. 1223 77

In the presence of 30% glycerol, the cilia of a permeabilized cell model from Paramecium exhibit dynamic orientation changes while displaying only a restricted cyclic beating with a very small amplitude. The direction of cilia under these conditions corresponds to the direction of the effective power stroke of cilia beating in the absence of glycerol, i.e., pointing posteriorly in the absence of Ca2+ and anteriorly at > 10(-6) M Ca2+. Ciliary reorientation toward the posterior in response to the removal of Ca2+ is particularly conspicuous; all the cilia become predominantly pointing to the posterior end all through their beating phases. Previous studies suggested that the effect of glycerol is caused through modification of cAMP-dependent protein phosphorylation. To determine whether glycerol in fact affects ciliary reorientation through changes in protein phosphorylation, here we examined protein phosphorylation in the axonemes. Glycerol stimulated cAMP-induced phosphorylation of 29-kDa and 65-kDa proteins. The stimulation of phosphorylation was found to be partly due to the inhibition of endogenous phosphodiesterase (PDE), and partly due to the inhibition of the dephosphorylation of the 29-kDa and 65-kDa phosphoproteins within the axoneme. Thus glycerol appears to cause predominant posterior orientation of cilia by stimulating cAMP-dependent phosphorylation on those proteins. In addition, glycerol appears to inhibit ciliary beating through inhibition of dynein ATPase.
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PMID:Augmented ciliary reorientation response and cAMP-dependent protein phosphorylation induced by glycerol in triton-extracted Paramecium. 1568 82