Glycogen synthase kinase 3 (GSK3) is a highly conserved protein kinase regulating key cellular fu... more Glycogen synthase kinase 3 (GSK3) is a highly conserved protein kinase regulating key cellular functions. Its two isoforms, GSK3α and GSK3β, are encoded by distinct genes. In most tissues the two isoforms are functionally interchangeable, except in the developing embryo where GSK3β is essential. One functional allele of either of the two isoforms is sufficient to maintain normal tissue functions. Both GSK3 isoforms, present in sperm from several species including human, are suggested to play a role in epididymal initiation of sperm motility. Using genetic approaches, we have tested requirement for each of the two GSK3 isoforms in testis and sperm. Both GSK3 isoforms are expressed at high levels during the onset of spermatogenesis. Conditional knock out of GSK3α, but not GSK3β, in developing testicular germ cells in mice results in male infertility. Mice lacking one allele each of GSK3α and GSK3β are fertile. Despite overlapping expression and localization in differentiating spermati...
Four isoforms of serine/threonine phosphatase type I, PP1α, PP1β, PP1γ 1, and PP1γ 2, are derived... more Four isoforms of serine/threonine phosphatase type I, PP1α, PP1β, PP1γ 1, and PP1γ 2, are derived from three genes. The PP1γ 1 and PP1γ 2 isoforms are alternately spliced transcripts of the protein phosphatase 1 catalytic subunit gamma gene (Ppp1cc). While PP1γ 1 is ubiquitous in somatic cells, PP1γ 2 is expressed exclusively in testicular germ cells and sperm. Ppp1cc knockout male mice (-/-), lacking both PP1γ 1 and PP1γ 2, are sterile due to impaired sperm morphogenesis. Fertility and normal sperm function can be restored by transgenic expression of PP1γ 2 alone in testis of Ppp1cc (-/-) mice. The purpose of this study was to determine whether the PP1γ 1 isoform is functionally equivalent to PP1γ 2 in supporting spermatogenesis and male fertility. Significant levels of transgenic PP1γ 1 expression occurred only when the transgene lacked a 1-kb 3 UTR region immediately following the stop codon of the PP1γ 1 transcript. PP1γ 1 was also incorporated into sperm at levels comparable to PP1γ 2 in sperm from wild-type mice. Spermatogenesis was restored in mice expressing PP1γ 1 in the absence of PP1γ 2. However, males from the transgenic rescue lines were subfertile. Sperm from the PP1γ 1 rescue mice were unable to fertilize eggs in vitro. Intrasperm localization of PP1γ 1 and the association of the protein regulators of the phosphatase were altered in epididymal sperm in transgenic PP1γ 1 compared to PP1γ 2. Thus, the ubiquitous isoform PP1γ 1, not normally expressed in differentiating germ cells, could replace PP1γ 2 to support spermatogenesis and spermiation. However, PP1γ 2, which is the PP1 isoform in mammalian sperm, has an isoform-specific role in supporting normal sperm function and fertility.
Glycogen synthase kinase 3 (GSK3) is a highly conserved protein kinase regulating key cellular fu... more Glycogen synthase kinase 3 (GSK3) is a highly conserved protein kinase regulating key cellular functions. Its two isoforms, GSK3α and GSK3β, are encoded by distinct genes. In most tissues the two isoforms are functionally interchangeable, except in the developing embryo where GSK3β is essential. One functional allele of either of the two isoforms is sufficient to maintain normal tissue functions. Both GSK3 isoforms, present in sperm from several species including human, are suggested to play a role in epididymal initiation of sperm motility. Using genetic approaches, we have tested requirement for each of the two GSK3 isoforms in testis and sperm. Both GSK3 isoforms are expressed at high levels during the onset of spermatogenesis. Conditional knock out of GSK3α, but not GSK3β, in developing testicular germ cells in mice results in male infertility. Mice lacking one allele each of GSK3α and GSK3β are fertile. Despite overlapping expression and localization in differentiating spermati...
The multifaceted glycogen synthase kinase (GSK3) has an essential role in sperm and male fertilit... more The multifaceted glycogen synthase kinase (GSK3) has an essential role in sperm and male fertility. Since cyclic AMP (cAMP) plays an important role in sperm function, we investigated whether GSK3 and cAMP pathways may be interrelated. We used GSK3 and soluble adenylyl cyclase (sAC) knockout mice and pharmacological modulators to examine this relationship. Intracellular cAMP levels were found to be significantly lower in sperm lacking GSK3α or GSK3β. A similar outcome was observed when sperm cells were treated with SB216763, a GSK3 inhibitor. This reduction of cAMP levels was not due to an effect on sperm adenylyl cyclase but was caused by elevated phosphodiesterase (PDE) activity. The PDE4 inhibitor RS25344 or the general PDE inhibitor IBMX could restore cAMP levels in sperm lacking GSK3α or β-isoform. PDE activity assay also showed that hyperactivated PDE4 contributes in lowering of cAMP levels in GSK3α null sperm suggesting that in wild-type sperm PDE4 activity is kept in check by...
Background Immature mammalian oocytes are held arrested at prophase I of meiosis by an inhibitory... more Background Immature mammalian oocytes are held arrested at prophase I of meiosis by an inhibitory phosphorylation of cyclin-dependent kinase 1 (CDK1). Release from this meiotic arrest and germinal vesicle breakdown is dependent on dephosphorylation of CDK1 by the protein, cell cycle division 25B (CDC25B). Evidence suggests that phosphorylated CDC25B is bound to YWHA (14-3-3) proteins in the cytoplasm of immature oocytes and is thus maintained in an inactive form. The importance of YWHA in meiosis demands additional studies. Results Messenger RNA for multiple isoforms of the YWHA protein family was detected in mouse oocytes and eggs. All seven mammalian YWHA isoforms previously reported to be expressed in mouse oocytes, were found to interact with CDC25B as evidenced by in situ proximity ligation assays. Interaction of YWHAH with CDC25B was indicated by Förster Resonance Energy Transfer (FRET) microscopy. Intracytoplasmic microinjection of oocytes with R18, a known, synthetic, non-is...
Glycogen synthase kinase 3 (GSK3) is a highly conserved protein kinase regulating key cellular fu... more Glycogen synthase kinase 3 (GSK3) is a highly conserved protein kinase regulating key cellular functions. Its two isoforms, GSK3α and GSK3β, are encoded by distinct genes. In most tissues the two isoforms are functionally interchangeable, except in the developing embryo where GSK3β is essential. One functional allele of either of the two isoforms is sufficient to maintain normal tissue functions. Both GSK3 isoforms, present in sperm from several species including human, are suggested to play a role in epididymal initiation of sperm motility. Using genetic approaches, we have tested requirement for each of the two GSK3 isoforms in testis and sperm. Both GSK3 isoforms are expressed at high levels during the onset of spermatogenesis. Conditional knock out of GSK3α, but not GSK3β, in developing testicular germ cells in mice results in male infertility. Mice lacking one allele each of GSK3α and GSK3β are fertile. Despite overlapping expression and localization in differentiating spermati...
Four isoforms of serine/threonine phosphatase type I, PP1α, PP1β, PP1γ 1, and PP1γ 2, are derived... more Four isoforms of serine/threonine phosphatase type I, PP1α, PP1β, PP1γ 1, and PP1γ 2, are derived from three genes. The PP1γ 1 and PP1γ 2 isoforms are alternately spliced transcripts of the protein phosphatase 1 catalytic subunit gamma gene (Ppp1cc). While PP1γ 1 is ubiquitous in somatic cells, PP1γ 2 is expressed exclusively in testicular germ cells and sperm. Ppp1cc knockout male mice (-/-), lacking both PP1γ 1 and PP1γ 2, are sterile due to impaired sperm morphogenesis. Fertility and normal sperm function can be restored by transgenic expression of PP1γ 2 alone in testis of Ppp1cc (-/-) mice. The purpose of this study was to determine whether the PP1γ 1 isoform is functionally equivalent to PP1γ 2 in supporting spermatogenesis and male fertility. Significant levels of transgenic PP1γ 1 expression occurred only when the transgene lacked a 1-kb 3 UTR region immediately following the stop codon of the PP1γ 1 transcript. PP1γ 1 was also incorporated into sperm at levels comparable to PP1γ 2 in sperm from wild-type mice. Spermatogenesis was restored in mice expressing PP1γ 1 in the absence of PP1γ 2. However, males from the transgenic rescue lines were subfertile. Sperm from the PP1γ 1 rescue mice were unable to fertilize eggs in vitro. Intrasperm localization of PP1γ 1 and the association of the protein regulators of the phosphatase were altered in epididymal sperm in transgenic PP1γ 1 compared to PP1γ 2. Thus, the ubiquitous isoform PP1γ 1, not normally expressed in differentiating germ cells, could replace PP1γ 2 to support spermatogenesis and spermiation. However, PP1γ 2, which is the PP1 isoform in mammalian sperm, has an isoform-specific role in supporting normal sperm function and fertility.
Glycogen synthase kinase 3 (GSK3) is a highly conserved protein kinase regulating key cellular fu... more Glycogen synthase kinase 3 (GSK3) is a highly conserved protein kinase regulating key cellular functions. Its two isoforms, GSK3α and GSK3β, are encoded by distinct genes. In most tissues the two isoforms are functionally interchangeable, except in the developing embryo where GSK3β is essential. One functional allele of either of the two isoforms is sufficient to maintain normal tissue functions. Both GSK3 isoforms, present in sperm from several species including human, are suggested to play a role in epididymal initiation of sperm motility. Using genetic approaches, we have tested requirement for each of the two GSK3 isoforms in testis and sperm. Both GSK3 isoforms are expressed at high levels during the onset of spermatogenesis. Conditional knock out of GSK3α, but not GSK3β, in developing testicular germ cells in mice results in male infertility. Mice lacking one allele each of GSK3α and GSK3β are fertile. Despite overlapping expression and localization in differentiating spermati...
The multifaceted glycogen synthase kinase (GSK3) has an essential role in sperm and male fertilit... more The multifaceted glycogen synthase kinase (GSK3) has an essential role in sperm and male fertility. Since cyclic AMP (cAMP) plays an important role in sperm function, we investigated whether GSK3 and cAMP pathways may be interrelated. We used GSK3 and soluble adenylyl cyclase (sAC) knockout mice and pharmacological modulators to examine this relationship. Intracellular cAMP levels were found to be significantly lower in sperm lacking GSK3α or GSK3β. A similar outcome was observed when sperm cells were treated with SB216763, a GSK3 inhibitor. This reduction of cAMP levels was not due to an effect on sperm adenylyl cyclase but was caused by elevated phosphodiesterase (PDE) activity. The PDE4 inhibitor RS25344 or the general PDE inhibitor IBMX could restore cAMP levels in sperm lacking GSK3α or β-isoform. PDE activity assay also showed that hyperactivated PDE4 contributes in lowering of cAMP levels in GSK3α null sperm suggesting that in wild-type sperm PDE4 activity is kept in check by...
Background Immature mammalian oocytes are held arrested at prophase I of meiosis by an inhibitory... more Background Immature mammalian oocytes are held arrested at prophase I of meiosis by an inhibitory phosphorylation of cyclin-dependent kinase 1 (CDK1). Release from this meiotic arrest and germinal vesicle breakdown is dependent on dephosphorylation of CDK1 by the protein, cell cycle division 25B (CDC25B). Evidence suggests that phosphorylated CDC25B is bound to YWHA (14-3-3) proteins in the cytoplasm of immature oocytes and is thus maintained in an inactive form. The importance of YWHA in meiosis demands additional studies. Results Messenger RNA for multiple isoforms of the YWHA protein family was detected in mouse oocytes and eggs. All seven mammalian YWHA isoforms previously reported to be expressed in mouse oocytes, were found to interact with CDC25B as evidenced by in situ proximity ligation assays. Interaction of YWHAH with CDC25B was indicated by Förster Resonance Energy Transfer (FRET) microscopy. Intracytoplasmic microinjection of oocytes with R18, a known, synthetic, non-is...
Uploads
Papers by Alaa Eisa