Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The motility and acrosomal integrity of fowl spermatozoa in TES/NaCl buffer, with or without homogenized inner perivitelline layers (IPVL) prepared from laid fowl eggs, was almost negligible at 40 degrees C. However, motility became vigorous even at 40 degrees C when 2 mmol CaCl2/l was added, and the acrosome reaction was also stimulated in the presence, but not in the absence, of IPVL. The presence of deltamethrin or fenvalerate, specific inhibitors of protein phosphatase-type 2B (PP2B), did not permit the restoration of motility at 40 degrees C but, in the presence of IPVL, these compounds stimulated the acrosome reaction in a dose-dependent manner in the range of 1-1000 nmol/l. These results suggest that IPVL is necessary for the activation of the acrosome reaction in fowl spermatozoa and that Ca2+ plays an important role in the stimulation of motility and acrosomal exocytosis. Furthermore, it appears that the intracellular molecular mechanisms for the regulation of the acrosome reaction of fowl spermatozoa are different from those for the restoration of motility, i.e. protein dephosphorylation by PP2B in the former but not in the latter case.
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PMID:Protein phosphatase-type 2B is involved in the regulation of the acrosome reaction but not in the temperature-dependent flagellar movement of fowl spermatozoa. 1557 96

The signal transduction pathways involved in the regulation of the acrosome reaction and motility of fowl spermatozoa were investigated. The motility and acrosomal integrity of fowl spermatozoa in TES/NaCl buffer, with or without homogenised inner perivitelline layers (IPVL), prepared from laid fowl eggs, was almost negligible at 40 degrees C. In the presence of 2 mmol CaCl(2)/l at 40 degrees C, motility became vigorous and the acrosome reaction was stimulated when IPVL was added. In the absence of Ca(2+), motility was stimulated by the addition of calyculin A and okadaic acid, both specific inhibitors of protein phosphatase-type 1 (PP1) and -type 2A (PP2A), but Okadaic acid, which is a weaker inhibitor of PP1, did not completely restore motility at 40 degrees C. However, the acrosome reaction was significantly and equally stimulated in a dose-dependent manner by both inhibitors in the range of 10-1000 nmol/l, when spermatozoa were incubated with IPVL but without Ca(2+). These inhibitors did not stimulate the acrosome reaction in the absence of IPVL. The vigorous motility of spermatozoa, stimulated by the addition of Ca(2+), was reduced gradually as the concentrations of SC-9, a selective activator of protein kinase C (PKC), were increased and a similar SC-9-induced inhibition was observed in the acrosome reaction in the presence of Ca(2+) and IPVL. These results confirm that IPVL is necessary for the activation of the acrosome reaction in fowl spermatozoa and that Ca(2+) plays an important role in the stimulation of motility and acrosomal exocytosis. Furthermore, it appears that the intracellular molecular mechanisms for the regulation of acrosome reaction of fowl spermatozoa are different from those for the restoration of motility, i.e., protein dephosporylation involving PP1 and/or PP2A in the former, and PP1 alone in the latter case. In addition, the activation of PKC may contribute to a decrease in the flagellar movement and acrosome reaction of fowl spermatozoa.
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PMID:Regulation of acrosome reaction of fowl spermatozoa: evidence for the involvement of protein kinase C and protein phosphatase-type 1 and/or -type 2A. 1673 41

The ability to maintain cellular volume is an important general physiological function, which is achieved by specific molecular mechanisms. Hypotonically induced swelling results in the opening of K+ and Cl- ion channels, through which these ions exit with accompanying water loss. This process is known as regulatory volume decrease (RVD). The molecular mechanisms that control the opening of the ion channels in spermatozoa are as yet poorly understood. The present study investigated pathways of osmo-signalling using boar spermatozoa as a model. Spermatozoa were diluted into isotonic and hypotonic Hepes-buffered saline in the presence or absence of effector drugs, and at predetermined intervals volume measurements were performed electronically. Treatment with protein kinase C (PKC) inhibitors staurosporine, bismaleimide I and bismaleimide X led to dose-dependent increases of both isotonic and hypotonic volumes (P<0.05). However, as the isotonic volume was affected more than the hypotonic volume, the kinase inhibitors appeared to improve RVD, whereas activation of PKC with phorbol dibutyrate blocked RVD. The increase in isotonic cell volume induced by bismaleimide X was observed in chloride-containing medium but not in the medium in which chloride was replaced by sulphate, implying that PKC was involved in the control of chloride channel activity, e.g. by closing the channel after volume adjustment. The protein phosphatase PP1/PP2 inhibitors calyculin and okadaic acid increased the isotonic volume only slightly but they greatly increased the relative cell volume and blocked RVD. The activation of RVD processes was found to be cAMP-dependent; incubation with forskolin and papaverine improved volume regulation. Moreover, papaverine was able to overcome the negative effect of protein phosphatase inhibitors. The mechanism of sperm RVD appears to involve (a) alterations in protein phosphorylation/dephosphorylation balance brought about by PKC and PP1 and (b) a cAMP-dependent activating pathway.
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PMID:Signalling pathways involved in the control of sperm cell volume. 1724 33

The intracellular mediators cyclic AMP, calcium and pH regulate sperm function through changes in protein phosphorylation. Protein phosphorylation is the net result of the actions of protein kinases and phosphatases. The protein phosphatase isoform, PPlgamma2, with a unique C-terminus extension is highly enriched in spermatozoa and testis. Changes in PPlgamma2 catalytic activity, its phosphorylation, and binding to its regulatory proteins change during epididymal maturation. Thus PPgamma2 is a key protein in sperm motility regulation; decreased enzyme activity is associated with increased motility. This review summarizes the current knowledge of this sperm protein phosphatase. The biochemical properties of its regulatory proteins, sds22 and protein 14-3-3, among others, are discussed. Future studies will elucidate sperm signalling pathways involving PP1gamma2 and determine if the unique structure of PP1gamma2 is critical to normal male gamete development and function. Understanding the role of PP1gamma2 will not only contribute to the basic understanding of male gamete functions but also has practical applications in clinical andrology and in the development of male contraceptives.
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PMID:Regulation of sperm function by protein phosphatase PP1gamma2. 1756 66

The serine/threonine phosphatase (PP1) isoform PP1 gamma 2, predominantly expressed in the testis, is a key enzyme in spermatozoa. High PP1 gamma 2 catalytic activity holds motility in check in immature spermatozoa. Inhibition of PP1 gamma 2 causes motility initiation in immature spermatozoa and motility stimulation and changes in flagellar beat parameters in mature spermatozoa. The PP1 gamma 2 isoform is present in all mammalian spermatozoa studied: mouse, rat, hamster, bovine, non-human primate and man. We have now identified at least four of its regulatory proteins that regulate distinct pools of PP1 gamma 2 within spermatozoa. Our studies provide new insights into biochemical mechanisms underlying development and regulation of sperm motility. We hypothesize that changes in sperm PP1 gamma 2 activity as a result of phosphorylation and reversible binding of the regulatory proteins to the catalytic subunit are critical in the development and regulation of motility and the ability of sperm to fertilize eggs. Targeted disruption of the Ppp1cc gene, which encodes the PP1 gamma 1 or PP1 gamma 2 isoforms, causes male infertility in mice as a result of impaired spermiogenesis. Our observations suggest that, in addition to motility, the protein phosphatase PP1 gamma 2 might play an isoform-specific function in the development of specialized flagellar structures of mammalian spermatozoa.
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PMID:Protein phosphatase PP1 gamma 2 in sperm morphogenesis and epididymal initiation of sperm motility. 1758 81

Mammalian spermatozoa acquire the capacity for motility and fertilization during the transit through the epididymis under the control of different factors, such as cAMP, intracellular pH, intracellular calcium and phosphorylation of sperm proteins. As the acquisition of functional competence including gaining motility during epididymal transit occurs in the complete absence of contemporaneous gene transcription and translation on the part of the spermatozoa, it is widely accepted that post-translational modifications are the only means by which spermatozoa can acquire functionality. Serine-threonine protein phosphatase 1 (PP1) together with their testis/sperm-specific interacting proteins might be involved in this regulatory mechanism. PP1alpha, PP1beta/delta, PP1gamma1 and PP1gamma2 are all expressed in the testis whereas PP1gamma2 is the only isoform expressed on spermatozoa. I2, I3, sds22, 14-3-3 and hsp90 are associated with PP1gamma2 in spermatozoa located on the sperm head and tail. Activity of PP1gamma2 and the binding pattern to these regulatory proteins changes in spermatozoa recruited from the caput and those from the cauda part of the epididymis. In this review, we summarize the possible roles of PP1 on spermatozoa during spermatogenesis and flagellar motility control. We suggest that PP1 might take part in the inhibition of the sperm motility activation by interacting with AKAPs and CAMKII. A hypothesized signaling pathway of mammalian sperm motility activation and PP1's function has been proposed.
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PMID:Role(s) of the serine/threonine protein phosphatase 1 on mammalian sperm motility. 1785 41

Previous studies from our laboratory have identified MPS, a 100-kDa protein, as the major phosphoprotein substrate of caprine sperm ecto-cyclic AMP independent protein kinase. In this study the isolated (32)P-labelled MPS has been incorporated into mature caprine (Capra indicus) cauda-epididymal spermatozoa with the help of cell electroporation technique to investigate the effect of MPS on sperm flagellar motility. The optimum conditions for electroporation of sperm cells consisted of exposure of 0.2 ml of sperm cells (2 x 10(8)/ml) to external electric field of intensity 1.5 kV/cm and capacitation of 25 microF at 4 degrees C and post-pulse incubation at 37 degrees C for 1 hr. when nearly 50% of the cells lost motility. Scanning electron micrographs (SEM) demonstrate the formation of micro-pores and local osmotic swelling in the electroporated spermatozoa. MPS incorporation was maximal when its concentration was 30 microg/ml (300 pmol) in the medium and when the post-pulse incubation time was 60 min. At maximum (75%) MPS incorporation, total and forward motility increments were also maximum: 34% (P < 0.01) and 32% (P < 0.01), respectively. The subcellular fractionation data show that major portion of the introduced MPS was bound to the plasma-membrane of spermatozoa. The 32P-labelled electrophoresed intact spermatozoa lost radioactivity due to the action of the endogenous ecto-phosphoprotein phosphatase. Therefore MPS is primarily localised on the sperm external surface leaving its phosphate group(s) oriented in the extracellular medium. The data provided further evidence to strengthen the view that MPS is an ecto-phosphoprotein and that it plays an important role in the regulation of sperm flagellar motility.
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PMID:Role of the major ecto-phosphoprotein in sperm flagellar motility using a cell electroporation method. 1819 70

In order to reveal the involvement of the sperm postacrosomal region in the acrosome reaction, we examined the effects of the protein phosphatase inhibitor calyculin A on the postacrosomal protein serine/threonine phosphorylation state and acrosome morphology in boar spermatozoa incubated with a cAMP analog. Proteins were highly phosphorylated on the serine/threonine residues only in the postacrosomal region before incubation. After 90-min incubation without calyculin A, the protein phosphorylation state declined in the postacrosomal region irrespective of the capacitation state while it remained under the detectable level in the other regions of the sperm head. However, addition of calyculin A effectively suppressed the decline in protein phosphorylation state and increased an inactive form of protein phosphatase 1 in the postacrosomal region. On the other hand, this inhibitor had no influence on the protein phosphorylation state in the acrosome and equatorial segment. After incubation without calyculin A for 180 or 360 min, many spermatozoa exhibited acrosomal changes and loss that indicated occurrence of the acrosome reaction. However, addition of calyculin A significantly blocked these events. These results are consistent with our suggestion that postacrosomal serine/threonine-phosphorylated proteins are involved in suppression of the acrosome reaction in boar spermatozoa in vitro.
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PMID:Effects of protein phosphatase inhibitor calyculin a on the postacrosomal protein serine/threonine phosphorylation state and acrosome reaction in boar spermatozoa incubated with a cAMP analog. 1830 66

Protein serine/threonine phosphorylation in mammalian sperm flagella has been considered to play important roles in regulation of motility. Protein phosphorylation state reflects balance of enzymatic activities between protein phosphatases and protein kinases [predominantly protein kinase A (PKA)]. The aims of this study were to disclose roles of protein phosphatases in the regulation of sperm motility and to provide evidence for suppression of PKA full activation by protein phosphatases in sperm flagella. Mouse epididymal spermatozoa were incubated with a cell-permeable protein phosphatase 1 (PP1)/protein phosphatase 2A (PP2A) inhibitor (calyculin A: 25-125 nM) at 37.5 C. After incubation, they were used for immunodetection of phosphorylated proteins, PKA and PP1 gamma2, assessment for motility and co-immunoprecipitation of PP1gamma2 with PKA. Incubation with calyculin A enhanced the phosphorylation states of several proteins (>250 kDa, 170 kDa, 155 kDa, 140 kDa and 42 kDa for serine/threonine phosphorylation and 70 kDa for tyrosine phosphorylation) and PKA catalytic subunits [at the autophosphorylation residue (Thr-197) for its full enzymatic activation] in the flagella. Coincidently, this incubation induced changes of sperm flagellar movement from the progressive type to the hyperactivation-like type. Indirect immunofluorescence and co-immunoprecipitation showed that PKA was co-localized with PP1 gamma2 in the principal pieces of sperm flagella. These findings suggest that calyculin A-sensitive protein phosphatases (PP1/PP2A) suppress full activation of PKA as well as enhancement of the phosphorylation states of other flagellar proteins in sperm flagella in order to prevent precocious changes of flagellar movement from the progressive type to hyperactivation.
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PMID:Calyculin A-sensitive protein phosphatases are involved in maintenance of progressive movement in mouse spermatozoa in vitro by suppression of autophosphorylation of protein kinase A. 1929 61

Two isoforms of phosphoprotein phosphatase 1, PPP1CC1 and PPP1CC2, are translated from alternatively spliced transcripts of a single gene, Ppp1cc, and differ only at their extreme C-termini. While PPP1CC1 expression is almost ubiquitous, PPP1CC2 is largely restricted to testicular germ cells and mature spermatozoa. Targeted deletion of Ppp1cc leads to sterility of -/- males due to a combination of gross structural defects in developing spermatids resulting in apoptosis and faulty spermiation. Because PPP1CC2 is the only PP1 isoform that demonstrates high-level expression in wild-type meiotic and postmeiotic male germ cells, we have tested whether its loss in Ppp1cc-/- males is largely responsible for manifestation of this phenotype by expressing PPP1CC2 transgenically in the testis of Ppp1cc-/- mice (rescue mice). Herein, we demonstrate that PPP1CC2 expression in the Ppp1cc-/- testis is antiapoptotic, thus reestablishing spermatid development and spermiation. However, because aberrant flagellar morphogenesis is incompletely ameliorated, rescue males remain infertile. Because these results suggest that expression of PPP1CC2 in developing germ cells is essential but insufficient for normal spermatogenesis to occur, appropriate spatial and temporal expression of both PPP1CC isoforms in the testis during spermatogenesis appears to be necessary to produce structurally normal fertility-competent spermatozoa.
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PMID:Expression of transgenic PPP1CC2 in the testis of Ppp1cc-null mice rescues spermatid viability and spermiation but does not restore normal sperm tail ultrastructure, sperm motility, or fertility. 1942 Mar 86


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