Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The low involvement of glucose metabolism in early preimplantation embryos has suggested the presence of metabolic blocks in the glycolytic pathway. Genetic expression of hexokinase (HK), glucose-6-phosphate isomerase (GPI) or phosphofructokinase (PFK) were qualitatively analysed using the reverse transcription nested polymerase chain reaction (RT-nested PCR) in individual human immature oocytes at the germinal vesicle (GV) stage and in single non-fertilised human metaphase II (MII) oocytes, after IVF or ICSI failures. Transcripts encoding for HK, GPI and PFK were detectable in the majority of the oocytes analysed, and with different expression patterns. GPI transcripts were consistently present and appear to be constitutively expressed during GV and MII stages. In contrast, low quantities of transcripts encoding for HK and PFK were observed in all oocytes analysed. Our data revealed that the metabolic block previously reported at GPI or PFK levels underwent post-transcriptional regulation. The expression profiles of HK and PFK transcripts in GV and MII reflect a low level of transcription or active translation of maternal transcripts during oocyte maturation. Nevertheless, enzymatic activities of HK and PFK have previously been determined in human oocytes. This suggests that HK and PFK may be accumulated in protein (enzyme) form instead of maternal mRNA during human oocyte maturation. The expression pathway of glycolytic metabolism reflects the presence of different mechanisms involved in gene expression/regulation at the transcriptional and translational level and their accumulation during human oocyte maturation.
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PMID:Glucose metabolism during the final stage of human oocyte maturation: genetic expression of hexokinase, glucose phosphate isomerase and phosphofructokinase. 1021 16

Previous studies have shown that developmental kinetic rates following IVF are lower in female than in male blastocysts and that this may be related to differences in glucose metabolism. In addition, an inhibition of phosphatidylinositol 3-kinase (PI3-K) inhibits glucose uptake in murine blastocysts. Therefore, the aim of this study was to identify and compare the expression of proteins involved in glucose metabolism (hexokinase-I, HK-I; phosphofructokinase-1, PFK-1; pyruvate kinase 1/2, PK1/2; glyceraldehyde-3-phosphate dehydrogenase, GAPDH; glucose transporter-1, GLUT-1; and glycogen synthase kinase-3, GSK-3) in male and female bovine blastocysts to determine whether PI3-K has a role in the regulation of the expression of these proteins. Hexokinase-I, PFK-1, PK1/2, GAPDH and GLUT-1 were present in bovine embryos. Protein expression of these proteins and GSK-3 was significantly higher in male compared with female blastocysts. Inhibition of PI3-K with LY294002 significantly decreased the expression of HK-I, PFK-1, GAPDH, GSK-3A/B and GLUT-1. Results showed that the expression of glycolytic proteins HK-I, PFK-1, GAPDH and PK1/2, and the transporters GLUT-1 and GSK-3 is regulated by PI3-K in bovine blastocysts. Moreover, the differential protein expression observed between male and female blastocysts might explain the faster developmental kinetics seen in males, as the expression of main proteins involved in glycolysis and glycogenogenesis was significantly higher in male than female bovine embryos and also could explain the sensitivity of male embryos to a high concentration of glucose, as a positive correlation between GLUT-1 expression and glucose uptake in embryos has been demonstrated.
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PMID:Differential glycolytic and glycogenogenic transduction pathways in male and female bovine embryos produced in vitro. 2228 Oct 81

The expression pattern of glucose metabolism genes (hexokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase [G6PDH], lactate dehydrogenase [LDH], and pyruvate dehydrogenase [PDH]) were studied in buffalo in vitro-matured oocytes and in vitro-produced embryos cultured under different glucose concentrations (0 mM, 1.5 mM, 5.6 mM, and 10 mM) during in vitro maturation of oocytes and culture of IVF produced embryos. The expression of the genes varied significantly over the cleavage stages under different glucose concentrations. Developmental rate of embryos was highest under a constant glucose level (5.6 mM) throughout during maturation of oocytes and embryo culture. Expression pattern of glucose metabolism genes under optimum glucose level (5.6 mM) indicated that glycolysis is the major pathway of glucose metabolism during oocyte maturation and early embryonic stages (pre-maternal to zygotic transition [MZT]) and shifts to oxidative phosphorylation during post-MZT stages in buffalo embryos. Higher glucose level (10 mM) caused abrupt changes in gene expression and resulted in shifting toward anaerobic metabolism of glucose during post-MZT stages. This resulted in decreased development rate of embryos during post-MZT stages. High expression of LDH and PDH in the control groups (0 mM glucose) indicated that in absence of glucose, embryos try to use available pyruvate and lactate sources, but succumb to handle the post-MZT energy requirement, resulting to poor development rate. Expression pattern of G6PDH during oocyte maturation as well early embryonic development was found predictive of quality and development competence of oocytes/ embryos.
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PMID:Expression pattern of glucose metabolism genes in relation to development rate of buffalo (Bubalus bubalis) oocytes and in vitro-produced embryos. 2399 43