Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myotonic dystrophy (DM) is commonly associated with CTG repeat expansions within the gene for DM-protein kinase (DMPK). The effect of altered expression levels of DMPK, which is ubiquitously expressed in all muscle cell lineages during development, was examined by disrupting the endogenous Dmpk gene and overexpressing a normal human DMPK transgene in mice. Nullizygous (-/-) mice showed only inconsistent and minor size changes in head and neck muscle fibres at older age, animals with the highest DMPK transgene expression showed hypertrophic cardiomyopathy and enhanced neonatal mortality. However, both models lack other frequent DM symptoms including the fibre-type dependent atrophy, myotonia, cataract and male-infertility. These results strengthen the contention that simple loss- or gain-of-expression of DMPK is not the only crucial requirement for development of the disease.
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PMID:Abnormal myotonic dystrophy protein kinase levels produce only mild myopathy in mice. 867 18

Several endocrine and neuronal functions are governed by the cAMP-dependent signalling pathway. In eukaryotes, transcriptional regulation upon stimulation of the adenylyl cyclase signalling pathway is mediated by a family of cAMP-responsive nuclear factors. This family consists of a large number of members that may act as activators or repressors. These factors contain the basic domain/ leucine zipper motifs and bind as dimers to cAMP-response elements (CRE). The function of CRE-binding proteins (CREBs) is modulated by phosphorylation by several kinases. Direct activation of gene expression by CREB requires phosphorylation by the cAMP-dependent protein kinase A to the serine-133 residue. Among the repressors, ICER (Inducible cAMP Early Repressor) deserves special mention. ICER is generated from an alternative CREM promoter and constitutes the only inducible cAMP-responsive element binding protein. Furthermore, ICER negatively autoregulates the alternative promoter, thus generating a feedback loop. In contrast to the other members of the CRE-binding protein family, ICER expression is tissue specific and developmentally regulated. The kinetics of ICER expression are characteristic of an early response gene. Our results indicate that CREM plays a key physiological and developmental role within the hypothalamic-pituitary-gonadal axis. We have previously shown that the transcriptional activator CREM is highly expressed in postmeiotic cells. Spermiogenesis is a complex process by which postmeiotic male germ cells differentiate into mature spermatozoa. This process involves remarkable structural and biochemical changes that are under the hormonal control of the hypothalamic-pituitary axis. We have addressed the specific role of CREM in spermiogenesis using CREM-mutant mice generated by homologous recombination. Analysis of the seminiferous epithelium from mutant male mice reveals that spermatogenesis stops at the first step of spermiogenesis. Late spermatids are completely absent, while there is a significant increase in apoptotic germ cells. A series of postmeiotic germ cell-specific genes are not expressed. Mutant male mice completely lack spermatozoa. This phenotype is reminiscent of cases of human infertility. We have shown that ICER is regulated in a circadian manner in the pineal gland, the site of the hormone melatonin production. This night-day oscillation is driven by the endogenous clock (located in the suprachiasmatic nucleus, SCN). The synthesis of melatonin is regulated by a rate-limiting enzyme, the serotonin N-acetyltransferase (NAT). By using the CREM-deficient mice and by analysis of the regulatory region of the gene encoding the serotonin NAT, we have established that ICER is responsible for the amplitude and rhythmicity of NAT and thus for the oscillation in the hormonal synthesis of melatonin.
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PMID:Coupling signalling pathways to transcriptional control: nuclear factors responsive to cAMP. 923 50

Several endocrine and neuronal functions are governed by the cAMP-dependent pathway. Transcriptional regulation upon stimulation of this pathway is mediated by a family of cAMP-responsive nuclear factors. This family consists of a large number of members, which may act as activators or repressors. These factors contain the basic domain/leucine zipper motifs and bind as dimers to cAMP-response elements (CRE). CRE-binding protein (CREBs) function is modulated by phosphorylation by several kinases. Direct activation of gene expression by CREB requires phosphorylation by the cAMP-dependent PKA to serine 133. Among the repressors, ICER (Inducible cAMP Early Repressor) deserves special mention. ICER is generated from an alternative CREM promoter and is the only inducible CRE-binding protein. ICER negatively autoregulates the alternative promoter, generating a feedback loop. ICER expression is tissue specific and developmentally regulated. The kinetics of ICER expression are characteristic of an early response gene. CREM plays a key physiological and developmental role within the hypothalamic-pituitary-gonadal axis. The transcriptional activator CREM is highly expressed in postmeiotic cells. The role of CREM in spermiogenesis was addressed using CREM knock-out mice. Spermatogenesis stops at the first step of spermiogenesis in the mutants and there is a significant increase in apoptotic germ cells. This phenotype is reminiscent of cases of human infertility. ICER is regulated in a circadian manner in the pineal gland, the site of the hormone melatonin production. This night-day oscillation is driven by the endogenous clock (located in the suprachiasmatic nucleus). The synthesis of melatonin is regulated by a rate-limiting enzyme, serotonin N-acetyltransferase (NAT). Analysis of the CREM-null mice and of the promoter of the NAT gene revealed that ICER controls the amplitude and rhythmicity of NAT, and thus the oscillation in the hormonal synthesis of melatonin.
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PMID:Coupling gene expression to cAMP signalling: role of CREB and CREM. 959 51

A cDNA encoding for a sperm antigen, designated NZ-2, was cloned and sequenced from human testis cDNA-lambda gt11 expression library by using antibodies to human sperm surface antigens belonging to 14-18 kD molecular regions. These sperm antigens are involved in binding to zona pellucida of the human oocyte. Computer generated translation analysis of 963-bp cDNA yielded an open reading frame (ORF) of 163 amino acids (aa) with first ATG, Met start codon at nucleotide (nt) 335 and the stop codon TAA at nt 824. The NZ-2 cDNA has 335-bp 5' and 139-bp 3' noncoding regions. The translated protein has a calculated molecular weight of approximately 19 kD, and has two casein kinase II (CK-2) sites at aa 94-97 and 149-152, respectively. Extensive computer search in the GenBank, National Biomedical Research Foundation (NBRF), and Swiss database indicates it to be a novel protein, having 99.5% nt sequence similarity, except for the first 40-bp, only with the human bacterial artificial chromosome (BAC) containing cloned human sperm DNA, at position 76935-76009. The in vitro translated product of T3 RNA polymerase by using NZ-2 cDNA digested with XhoI yielded a protein band of approximately 20 kD, indicating it to be sense strand. The in vitro translated product of T7 RNA polymerase by using NZ-2 cDNA digested with NotI did not yield any protein band, indicating it to be antisense strand. The approximately 20 kD protein was recognized specifically by the antisperm IgG, not by the control IgG in the Western blot procedure. Neither antisperm IgG nor control IgG recognized any protein band in the in vitro translation products of the antisense strand. The human genomic DNAs from three different cells/tissues namely, sperm, kidney, and testis when cut by HindIII, and then hybridized with the NZ-2 cDNA probe in the Southern blot procedure, showed restriction fragment length polymorphism (RFLP). The recombinant human sperm NZ-2 antigen may find applications in the development of a contraceptive vaccine, and diagnosis and treatment of infertility in humans.
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PMID:Cloning and sequencing of cDNA encoding for a human sperm antigen involved in fertilization. 974 Mar 25

The involvement of cyclin-dependent kinase inhibitors in differentiation remains unclear: are the roles of cyclin-dependent kinase inhibitors restricted to cell cycle arrest; or also required for completion of the differentiation program; or both? Here, we report that differentiation of luteal cells can be uncoupled from growth arrest in p27-deficient mice. In these mice, female-specific infertility correlates with a failure of embryos to implant at embryonic day 4.5. We show by ovarian transplant and hormone reconstitution experiments that failure to regulate luteal cell estradiol is one physiological mechanism for infertility in these mice. This failure is not due to a failure of p27-deficient granulosa cells to differentiate after hormonal stimulation; P450scc, a marker for luteal progesterone biosynthesis, is expressed and granulosa cell-specific cyclin D2 expression is reduced. However, unlike their wild-type counterparts, p27-deficient luteal cells continue to proliferate for up to 3.5 days after hormonal stimulation. By day 5.5, however, these cells withdraw from the cell cycle, suggesting that p27 plays a role in the early events regulating withdrawal of cells from the cell cycle. We have further shown that in the absence of this timely withdrawal, estradiol regulation is perturbed, explaining in part how fertility is compromised at the level of implantation. These data support the interpretation of our previous observations on oligodendrocyte differentiation about a role for p27 in establishing the nonproliferative state, which in some cases (oligodendrocytes) is required for differentiation, whereas in other cases it is required for the proper functioning of a differentiated cell (luteal cell).
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PMID:The absence of p27Kip1, an inhibitor of G1 cyclin-dependent kinases, uncouples differentiation and growth arrest during the granulosa->luteal transition. 975 Nov 22

Various endocrine and neuronal functions are governed by the cAMP-dependent signaling pathway. In eukaryotes, transcriptional regulation upon stimulation of the adenylyl cyclase signaling pathway is mediated by a family of cAMP-responsive nuclear factors. This family consists of a large number of members which may act as activators or repressors. These factors contain the basic domain/leucine zipper motifs and bind as dimers to cAMP-response elements (CRE). The function of CRE-binding proteins (CREBs) is modulated by phosphorylation by several kinases. Direct activation of gene expression by CREBs requires phosphorylation by the cAMP-dependent protein kinase A to the serine-133 residue. The gene CREM encodes various transcription factors which play key physiological and developmental roles within the hypothalamic-pituitary-gonadal axis. We have previously shown that the transcriptional activator CREMtau is highly expressed in postmeiotic cells. Spermiogenesis is a complex process by which postmeiotic male germ cells differentiate into mature spermatozoa. This process involves remarkable structural and biochemical changes which are under the hormonal control of the hypothalamic-pituitary axis. We have addressed the specific role of CREM in spermiogenesis using CREM-mutant mice generated by homologous recombination. Analysis of the seminiferous epithelium from mutant male mice reveals that spermatogenesis stops at the first step of spermiogenesis. Late spermatids are completely absent while there is a significant increase in apoptotic germ cells. A series of postmeiotic germ cell-specific genes are not expressed. Mutant male mice completely lack spermatozoa. This phenotype is reminiscent of cases of human infertility.
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PMID:Regulating the balance between differentiation and apoptosis: role of CREM in the male germ cells. 984 51

The production of male gametes depends on the concerted action of the two gonadotropins FSH and LH on the testis. The action of LH is mediated through the production of testosterone by the Leydig cells. Since male germ cells possess neither FSH nor androgen receptors, the action of FSH and testosterone occurs through the Sertoli cells. Although the precise function of these two hormones remains elusive, the existing evidence suggest that both FSH and testosterone are able to stimulate all phases of spermatogenesis. In the male FSH is required for the determination of Sertoli cell number, and for induction and maintenance of normal sperm production. The crucial role of FSH in male gonadal function has been clearly illustrated by the discovery of a patient with an activating mutation of the FSH receptor. This patient had been hypophysectomized because of a pituitary tumor and, under testosterone substitution was unexpectedly fertile in spite of undetectable serum gonadotropin levels and had fathered three children. In this patient we could demonstrate a heterozygous activating mutation of the FSH receptor which resulted in cAMP production independent of FSH stimulation. This finding represents the first description of an activating mutation of the FSH receptor and demonstrates that FSH alone maintains spermatogenesis in man. On the other hand, the effects of the lack of FSH action are unclear. Among five men with a homozygous inactivating mutation of the FSH receptor only one was infertile and spermatogenesis was variably affected in the others. However, serum inhibin B values in these men were not completely suppressed and serum FSH levels were only moderately elevated, indicating the possibility that FSH receptor function was not completely abolished by the mutation. Elimination of FSH action is a prerequisite to suppress completely spermatogenesis for contraceptive purposes, while administration of both LH and FSH is necessary to induce sperm production in patients with hypogonadotropic hypogonadism. Experimental immunization of male monkeys against FSH markedly reduced germ cell proliferation and even induced infertility. At the cellular level, FSH stimulates the cAMP-dependent activation of protein kinase A in Sertoli cells, but the molecular mechanism of FSH action is poorly understood. In the primate, the gonadotropin withdrawal achieved by administration of a GnRH antagonist leads to a premeiotic arrest of germ cell proliferation, probably due to inhibition of the mitotic division of A-pale spermatogonia. Therefore, FSH might be the prime inducer of spermatogonial proliferation, while the successive maturation process could proceed independently of FSH. In summary, clinical and experimental evidence support the concept of an irreplaceble role of FSH in the primate. Only the combination of FSH and testosterone, however, supports a qualitatively and quantitatively fully normal spermatogenesis.
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PMID:Role of FSH in male gonadal function. 1045 80

Dimethoate is a widely used organophosphate insecticide that has been shown to disrupt reproductive function in animals. Although the pathogenesis of Dimethoate-induced reproductive toxicity remains to be determined, a reduction in serum testosterone levels is thought to play an important role in the development of Dimethoate-induced infertility. Since Leydig cells play a crucial role in male reproductive function by producing testosterone, the mouse MA-10 Leydig tumor cell line was used to determine if Dimethoate can directly block steroid hormone biosynthesis and to identify the site of steroidogenic inhibition. Dimethoate inhibited steroidogenesis in both a dose- and time-dependent manner without affecting total protein synthesis or protein kinase A activity. While it decreased the activity of the P450 side chain cleavage (P450 scc) enzyme, a reduction in the activity of this enzyme alone could not account for the level of Bu(2)cAMP-inhibited progesterone production. Instead, our results suggest that Dimethoate inhibited steroidogenesis primarily by blocking transcription of the steroidogenic acute regulatory (StAR) gene. This finding is significant since StAR protein mediates the rate-limiting and acutely-regulated step in steroidogenesis, the transfer of cholesterol from the outer to the inner mitochondrial membrane. This study indicates that StAR may be an important target for environmental pollutants which disrupt steroidogenesis and impair reproductive function.
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PMID:Dimethoate inhibits steroidogenesis by disrupting transcription of the steroidogenic acute regulatory (StAR) gene. 1105 39

cAMP signaling contributes to the control of the developmental progression of germ cells during the spermatogenic cycle. Genes regulated by cAMP include those encoding transcription factors such as the cAMP-responsive element modulator (CREM). The disruption of CREM gene expression in crem null mice results in arrest of spermatogenesis and infertility. The transcriptional control of the CREM gene is attributed to two promoters, P1 and P2. The P1 promoter constitutively activates the synthesis of messenger RNAs encoding activator (tau) and repressor (alpha) forms of CREM, whereas the cAMP-responsive P2 promoter activates the formation of messenger RNAs encoding the inducible cAMP early repressor. Here we report the identification of two additional promoters in the CREM gene, P3 and P4, that in the rat testis encode two novel transcriptional activator CREM isoforms, termed CREM theta1 and CREM theta2, respectively. Notably, the P3 and P4 promoters are activated by cAMP-dependent protein kinase, thereby providing cAMP-regulated transcription of CREM activators in addition to the established cAMP-regulated inducible cAMP early repressor. Analysis ex vivo of CREM gene expression in temporally staged segments of the seminiferous tubule during the spermatogenic cycle shows that the activities of the P1, P3, and P4 promoters are independently regulated. Our identification of the cAMP-activated P3 and P4 promoters that direct expression of the novel theta1 and theta2 activator isoforms of CREM brings further insight into the complex expression of the CREM gene during germ cell development and may have implications in understanding the control of fertility.
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PMID:Novel cyclic adenosine 3',5'-monophosphate (cAMP) response element modulator theta isoforms expressed by two newly identified cAMP-responsive promoters active in the testis. 1108 20

Mutants defective in the biosynthesis or signaling of brassinosteroids (BRs), plant steroid hormones, display dwarfism. Loss-of-function mutants for the gene encoding the plasma membrane-located BR receptor BRI1 are resistant to exogenous application of BRs, and characterization of this protein has contributed significantly to the understanding of BR signaling. We have isolated two new BR-insensitive mutants (dwarf12-1D and dwf12-2D) after screening Arabidopsis ethyl methanesulfonate mutant populations. dwf12 mutants displayed the characteristic morphology of previously reported BR dwarfs including short stature, short round leaves, infertility, and abnormal de-etiolation. In addition, dwf12 mutants exhibited several unique phenotypes, including severe downward curling of the leaves. Genetic analysis indicates that the two mutations are semidominant in that heterozygous plants show a semidwarf phenotype whose height is intermediate between wild-type and homozygous mutant plants. Unlike BR biosynthetic mutants, dwf12 plants were not rescued by high doses of exogenously applied BRs. Like bri1 mutants, dwf12 plants accumulated castasterone and brassinolide, 43- and 15-fold higher, respectively, providing further evidence that DWF12 is a component of the BR signaling pathway that includes BRI1. Map-based cloning of the DWF12 gene revealed that DWF12 belongs to a member of the glycogen synthase kinase 3beta family. Unlike human glycogen synthase kinase 3beta, DWF12 lacks the conserved serine-9 residue in the auto-inhibitory N terminus. In addition, dwf12-1D and dwf12-2D encode changes in consecutive glutamate residues in a highly conserved TREE domain. Together with previous reports that both bin2 and ucu1 mutants contain mutations in this TREE domain, this provides evidence that the TREE domain is of critical importance for proper function of DWF12/BIN2/UCU1 in BR signal transduction pathways.
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PMID:Arabidopsis brassinosteroid-insensitive dwarf12 mutants are semidominant and defective in a glycogen synthase kinase 3beta-like kinase. 1242 15


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