Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cumulus-free pig oocytes at the germinal vesicle (GV) stage were incubated in modified Brackett & Oliphant's medium with 5% fetal calf serum and 5mM caffeine with or without cryopreserved, ejaculated spermatozoa. When oocytes were transferred into modified tissue culture medium (TCM-199B at pH 7.4) supplemented with 10 IU/ml eCG, 10 IU/ml hCG and 1 microg/ml oestradiol-17beta after 8 h of incubation with spermatozoa and cultured for 0-48 h, 86-99% of oocytes were penetrated. Most (95-100%) oocytes penetrated 0-16 h after transfer had decondensed sperm chromatin. However, 24 h after transfer 47% and 33% of penetrated oocytes contained recondensed sperm chromatin and sperm metaphase chromosomes, respectively. The proportion of penetrated oocytes containing sperm metaphase chromosomes increased after 36-48 h of transfer (51-65%). The transformation of sperm nuclei to metaphase chromosomes was obtained in 75% and 79% of anaphase I (AI) to telophase I (TI) and metaphase II (MII) oocytes, respectively, but only in 38% of metaphase I (MI) oocytes. Moreover, such transformation was observed only in 1 of 30 oocytes at the stages of GV breakdown to prometaphase I and none of 69 oocytes at the GV stage. The transformation of sperm nuclei into metaphase chromosomes was completely inhibited in oocytes penetrated by eight or more spermatozoa. Well-developed male and female pronuclei were observed in only 3 (4%) of 77 oocytes penetrated 48 h after transfer. The proportion of oocytes reaching MII was greatly inhibited by sperm penetration; only 18% of penetrated oocytes, but 87% of non-inseminated oocytes, reached MII by 48 h after transfer. None of the oocytes penetrated by seven or more spermatozoa reached MII. Most (75%) oocytes were inhibited from the transition from MI to MII even though they were cultured for 48 h. The present results indicate that: (1) the cytoplasm of maturing oocytes possesses an activity for transforming sperm nuclei into metaphase chromosomes, (2) immature pig oocytes penetrated by spermatozoa can undergo meiotic maturation to MI, and (3) the transition of such oocytes from MI to MII is inhibited, suggesting that an activity of mitogen-activated protein kinase may be retarded.
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PMID:Transformation of sperm nuclei into metaphase chromosomes in maturing pig oocytes penetrated in vitro. 927 14

The motility of demembranated fowl spermatozoa was vigorous at 30 degrees C, but decreased markedly following the addition of mitogen-activated protein (MAP) kinase or p34cdc2 kinase substrate peptide. Dephosphorylation of approximately 116, 86 and 79-kDa proteins of demembranated spermatozoa was observed after the addition of MAP kinase or p34cdc2 kinase substrate peptide. The activities of MAP kinase and histone H1 kinase of spermatozoa, estimated by measuring the phosphorylation of myelin basic protein and histone H1 as substrates, were 1.22 and 0.29 pmol/min/ mg protein, respectively. Both enzymatic activities of spermatozoa were lower than those of chick brain, but higher than those of chick liver. These results suggest that the phosphorylation of axonemal and/or accessory cytoskeletal proteins mediated by MAP kinase and p34cdc2 kinase may be involved in the regulation of flagellar movement of fowl spermatozoa.
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PMID:The addition of mitogen-activated protein kinase and p34cdc2 kinase substrate peptides inhibits the flagellar motility of demembranated fowl spermatozoa. 936 94

Recent evidence indicates the presence of p21 Ras and of a protein with characteristics similar to mitogen-activated protein kinases (MAPKs), also known as extracellular signal-regulated kinases (ERKs), in mammalian spermatozoa, suggesting the occurrence of the Ras/ERK cascade in these cells. In the present study we investigated the subcellular localization of ERKs and their biological functions in human spermatozoa. Immunohistochemistry, immunofluorescence, confocal microscopy, and immunoelectron microscopy demonstrated localization of ERKs in the postacrosomal region of spermatozoa. After stimulation of acrosome reaction with the calcium ionophore A23187 and progesterone, ERKs were mostly localized at the level of the equatorial region, indicating redistribution of these proteins in acrosome-reacted spermatozoa. Two proteins of 42 and 44 kDa that are tyrosine phosphorylated in a time-dependent manner during in vitro capacitation were identified as p42 (ERK-2) and p44 (ERK-1) by means of specific antibodies. The increase in tyrosine phosphorylation of these proteins during capacitation was accompanied by increased kinase activity, as determined by the ability of ERK-1 and ERK-2 to phosphorylate the substrate myelin basic protein. The role of this activity in the occurrence of sperm capacitation was also investigated by using PD098059, an inhibitor of the MAPK cascade. The presence of this compound during in vitro capacitation inhibits ERK activation and significantly reduces the ability of spermatozoa to undergo the acrosome reaction in response to progesterone. Since only capacitated spermatozoa are able to respond to progesterone, these data strongly indicate that ERKs are involved in the regulation of capacitation. In summary, our data demonstrate the presence of functional ERKs in human spermatozoa and indicate that these enzymes are involved in activation of these cells during capacitation, providing new insight in clarifying the molecular mechanisms and the signal transduction pathways of this process.
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PMID:Extracellular signal-regulated kinases modulate capacitation of human spermatozoa. 962 9

The expression and phosphorylation/dephosphorylation of mitogen-activated protein (MAP) kinases during mouse spermatogenesis and epididymal sperm maturation have been investigated by immunoblotting and immunohistochemical staining with commercially available anti-ERK2 and anti-Active MAPK antibodies. Two forms of MAP kinases, p42ERK2 and p44ERK1, were expressed in a similar amount in spermatogenic cells at different stages. ERK1 and ERK2 were phosphorylated (activated) in early spermatogenic cells from primitive spermatogonia to zygotene primary spermatocytes, while only a small quantity of phosphorylated MAP kinases could be detected in pachytene primary spermatocytes and spermatids. MAP kinase activity in primative spermatogonia and preleptotene primary spermatocytes was the highest among spermatogenic cells. ERK1 and ERK2 were also present in epididymal spermatozoa, and their phosphorylation was increased while spermatozoa pass through epididymis and vas deferens for maturation. It would appear that MAP kinase activation may contribute to the mitotic proliferation of primative spermatogonia, an early phase of spermatogenic meiosis, and, later, sperm motility acquirement.
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PMID:Expression and phosphorylation of mitogen-activated protein kinases during spermatogenesis and epididymal sperm maturation in mice. 1044 5

Normal epididymal function is regulated by androgens and testicular factors. Our studies have been directed towards identifying testicular factors that regulate the function of the initial segment and the mechanisms by which this is achieved. The initial segment appears to be critical for normal sperm maturation in view of recent gene knock-out studies. Previous and ongoing studies from this and other laboratories have shown that the expression of several genes including proenkephalin, cystatin-related epididymal specific (CRES), 5 alpha-reductase and gamma-glutamyl transpeptidase (GGT) within the initial segment is highly dependent upon the presence of testicular factors. A lumicrine mechanism of regulation of these genes is proposed. The regulation of gamma-glutamyl transpeptidase (GGT) is described as a model enzyme for studying the role and identification of testicular factors. GGT appears to play an important role in the protection of spermatozoa from oxidative stress. Multiple GGT mRNAs (II-IV) are expressed within the epididymis, but GGT mRNA IV is the only form that is highly expressed in the initial segment, especially within zone 1A, and is regulated by testicular factors. Testicular factors control this transcript by regulating both its rate of transcription and its stability. Evidence is presented to suggest that basic fibroblast growth factor (bFGF) is a candidate testicular factor that regulates GGT activity in the epididymis. Basic FGF may regulate gene expression in the epididymis via the ras-raf-MAPK second messenger pathway and by members of the Ets transcription family.
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PMID:Testicular regulation of epididymal gene expression. 1064 65

Pig oocytes at metaphase II were activated by penetration of spermatozoa in cycloheximide-free and cycloheximide-containing fertilisation media. The precise nuclear stage, and the kinetics of degradation of cyclin B1 and dephosphorylation of MAP kinase were assessed after insemination. After maturation culture, 96% of oocytes reached metaphase II. At 6 h after insemination in cycloheximide-free medium, 68% of the oocytes were activated and had progressed to anaphase II or beyond. After 8 h, 89% of the oocytes were activated: a female pronucleus had formed and the heads of penetrating spermatozoa had enlarged and changed to male pronuclei. In the cycloheximide-containing medium, activation of oocytes started earlier than in cycloheximide-free medium. After 4 h, 43% of the oocytes were activated, and the percentage increased to 97% after 6 h. Pig cyclin B1 disappeared in the oocytes at 6 h after insemination in both cycloheximide-containing and cycloheximide-free media. Pig oocytes at metaphase II contained two types of MAP kinase--ERK 1 and ERK 2--in their active phosphorylated forms. At 8 h after insemination ERK 2 changed to the fast-migrating inactive form in the oocytes cultured in both cycloheximide-containing and cycloheximide-free media, although the shift-down was not complete. The change was delayed by 2 h after the degradation of cyclin B1 molecules. These results demonstrate that degradation of pig cyclin B1 molecules corresponds to the transition of the oocytes from metaphase II arrest to anaphase II/telophase II and was followed by MAP kinase dephosphorylation.
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PMID:Degradation of pig cyclin B1 molecules precedes MAP kinase dephosphorylation during fertilisation of the oocytes. 1085 86

Islet-brain1/JNK-interacting protein-1 (IB1/JIP-1) is a scaffold protein that organizes the JNK, MKK7, and MLK1 to allow signaling specificity. Targeted disruption of the gene MAPK8IP1 encoding IB1/JIP-1 in mice led to embryonic death prior to blastocyst implantation. In culture, no IB1/JIP-1(-/-) embryos were identified indicating that accelerated cell death occurred during the first cell cycles. IB1/JIP-1 expression was detected in unfertilized oocytes, in spermatozoa, and in different stages of embryo development. Thus, despite the maternal and paternal transmission of the IB1/JIP-1 protein, early transcription of the MAPK8IP1 gene is required for the survival of the fertilized oocytes.
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PMID:Islet-brain1/JNK-interacting protein-1 is required for early embryogenesis in mice. 1139 Mar 67

Extracellular signal-regulated kinases (ERKs), belonging to the family of mitogen-activated protein kinases (MAPKs), are cytoplasmic and nuclear serine/threonine kinases involved in the signal transduction of several extracellular effectors. Recent evidence indicates the presence of p21 Ras and the phosphorylation of ERK1 and ERK2, suggesting the occurrence of the Ras/ERK cascade in mammalian spermatozoa. The present article describes the biological role of ERK during the acrosome reaction of human spermatozoa on stimulation with zona pellucida (ZP). The mitogen-activated protein-kinase inhibitor PD098059 was used as a pharmacological tool to study the involvement of extracellular signal-regulated kinases in the induction of the acrosome reaction in human spermatozoa. This compound significantly inhibited the acrosome reaction induced by both ZP and the calcium ionophore A23187. These results suggest that ERKs are involved in the signal transduction pathway through which ZP stimulation works during the process of fertilization.
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PMID:The zona pellucida-induced acrosome reaction of human spermatozoa involves extracellular signal-regulated kinase activation. 1173 93

Our aim was to ascertain the role of the extracellular signal-regulated protein kinase (ERK) pathway in human sperm capacitation induced by fetal cord serum ultrafiltrate (FCSu) and its regulation by the superoxide anion (O(2)(-)*). Immunoblotting indicated the presence of Shc, Grb2, Ras(p21), Raf and ERK1 and 2 (ERK1/2) in spermatozoa. Grb2, Ras(p21), Raf and MEK inhibitors dose-dependently prevented sperm capacitation and protein tyrosine phosphorylation, without modifying sperm O(2)(-)* production. Therefore, the whole ERK cascade plays a role in capacitation, downstream of O(2)(-)* but upstream of protein tyrosine phosphorylation. Upon incubation with FCSu, the early (5 min) increase in ERK1/2 activity (as shown by double phosphorylation of the Thr-Glu-Tyr motif) was followed by an important decrease over the next 2 h; superoxide dismutase did not change this pattern. The phosphorylation of the Thr-Glu-Tyr motif present in other sperm proteins (16-33 kDa) also increased (5 min incubation with FCSu) and then progressively decreased, and this effect was regulated by O(2)(-)*, MEK and cAMP. The phospho-Ser/Thr-Pro content (characteristic of ERK1/2 substrates) of Triton-insoluble proteins (75 and 80 kDa) increased during capacitation and also appeared to be regulated by O(2)(-)* and the ERK pathway. Inhibition of ERK1/2 activation reduced lysophosphatidylcholine-induced acrosome reaction and the associated protein tyrosine phosphorylation. These results support a role for the ERK pathway in human sperm function.
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PMID:The extracellular signal-regulated kinase (ERK) pathway is involved in human sperm function and modulated by the superoxide anion. 1181 15

In a previous study involving the inhibition the mitogen-activated protein kinase (MAPK), extracellular signal regulated kinase (ERK), we found that the very specific MAPK kinase (MEK) inhibitor, PD098059, inhibited the zona pellucida (ZP) induced acrosome reaction. As an intact acrosome on the spermatozoa is a prerequisite in ensuring tight binding to the ZP, we investigated the zona binding potential of spermatozoa after PD098059 treatment of sperm, followed by exposure to solubilised human ZP and calcium ionophore (A23187). PD098059 treated spermatozoa, exposed to solubilised ZP, bound significantly more to the ZP, as compared to control spermatozoa also exposed to solubilised ZP (26.5 +/- 3.7 vs. 13.8 +/- 2.8, P < 0.05). No significant differences in binding to the ZP were observed between PD098059 treated and untreated sperm populations after A23187 exposure. These results can be interpreted to support the idea that the ZP-induced AR is the physiologically relevant exocytotic event, as it is the ZP-induced AR, and not the spontaneous (culture medium) or A23187 induced AR, that appears to be mediated through an ERK-mediated signal transduction process.
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PMID:Extracellular signal-regulated kinase activation involved in human sperm-zona pellucida binding. 1199 82


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