Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Spermatozoa are highly sensitive to oxidative stress. The epididymis, a natural sperm reservoir, has maturational and storage functions. The epididymis may also protect spermatozoa from oxidative injury by elaborating scavengers of reactive oxygen species (ROS). Therefore, we have evaluated the mRNA expression of antioxidant enzymes in the normal rat epididymis and the effects of efferent duct ligation no the expression of these enzymes. Adult rat epididymides were harvested, divided into caput, corpus and cauda and processed for RNA extraction. Additional adult rats were subjected to unilateral efferent duct ligation and the epididymides harvested at 1, 4, 8, 16 or 28 days after the procedure. Antioxidant enzyme mRNA expression was assessed by Northern blot analysis using 32P-labelled DNA probes derived from known cDNA sequences for classical cellular glutathione peroxidase (GSHPx), phospholipid hydroperoxide glutathione peroxidase (PHGPX), secretory epididymal glutathione peroxidase (E-GPX), copper-zinc superoxide dismutase (SOD), secretory epididymal superoxide dismutase (E-SOD) and catalase. Specific mRNA levels were measured, with gene expression evaluated relative to total RNA, not per organ. Variations in lane loading were controlled by measuring the levels of 28S ribosomal RNA. GSHPx, PHGPX, SOD and catalase mRNA were detected in the caput, corpus and cauda epididymis. E-GPX mRNA was only detected in the caput, whereas E-SOD mRNA was primarily detected in the corpus. At 28 days after efferent duct ligation, epididymal weight decreased by 34% relative to controls (p < 0.05). With the exception of PHGPX, the relative mRNA levels of the antioxidant enzymes studied did not change after efferent duct ligation. This study demonstrates that mRNAs for multiple antioxidant enzymes are expressed in the epididymis and that the relative expression of these enzymes remains largely unchanged in response to efferent duct ligation. Taken together, these results suggest that antioxidant enzymes may play an important, region-specific role in epididymal function. Expression of the secretory antioxidant enzymes E-SOD and E-GPX is region-specific, indicating that the need for antioxidant enzymes may vary along the length of the epididymis.
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PMID:Identification and characterization of antioxidant enzyme mRNAs in the rat epididymis. 929 18

The selenoenzyme phospholipid hydroperoxide glutathione peroxidase (PHGPx, EC 1.11.1.12) is present, in both free and membrane-bound form, in several mammalian tissues. It utilizes thiols such as glutathione to specifically scavenge phospholipid hydroperoxides. The testis exhibits the highest PHGPx-specific activity so far measured, and interest in the presence and function of the enzyme in this tissue has recently grown. Here we report the localization of PHGPx in rat epididymal spermatozoa and its distribution in subfractions obtained by sucrose density gradient centrifugation. Immunochemical evidence and enzymatic activity revealed for the first time that PHGPx is present in sperm heads and tail midpiece mitochondria. The binding of the enzyme to spermatozoa, head, and mitochondria was barely affected by ionic strength or thiols or detergents, as compared to the detachment of PHGPx obtained from testis nuclei. Moreover, we demonstrated that pure PHGPx exhibits a higher thiol-oxidase activity toward isolated epididymal caput protamines than toward protamines from epididymal cauda. These results suggest a role for the enzyme in the maturation of spermatozoa through the metabolism of hydroperoxides and sperm thiol oxidation, in addition to its serving as an antioxidant protector.
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PMID:Distribution and possible novel role of phospholipid hydroperoxide glutathione peroxidase in rat epididymal spermatozoa. 940 61

Mammalian caput and cauda epididymidal spermatozoa exhibit diverse stages of maturation, and their plasma membrane shows diverse composition and stability levels, thus enabling these spermatozoa to undergo the acrosomal reaction after transit through the epididymis. As a result, the study of antiperoxidative mechanisms is quite relevant, since epididymal spermatozoa must be properly protected against agents such as reactive oxygen species, which can impair the complex maturation process. We considered activities of certain enzymes (glutathione peroxidase [GPx], phospholipid hydroperoxide glutathione peroxidase [PHGPx], glutathione reductase [GR], superoxide dismutase [SOD], and catalase [CAT]) and the vitamin E content in isolated rat caput and cauda epididymidal spermatozoa. The results indicate that caput epididymidal sperm have significantly greater PHGPx (3.5x), GPx (2.4x), and SOD (1.7x) activities, as well as a greater amount of vitamin E (3.8x). There were no detectable differences in the GR and CAT activities of caput and cauda epididymidal spermatozoa. The substantial drop in PHGPx activity during epididymal transit is discussed in relation to an additional function of this enzyme: the use of caput sperm protamines as a sulfhydryl substrate. In vitro peroxidation of the two sperm populations by the free radical generator (azo-initiator) 2,2'-azobis(2-amidinopropane) dihydrochloride revealed that only about 13% of the vitamin E content of the caput epididymidal spermatozoa was consumed, which contrasts with the greater consumption (about 70%) of the vitamin in cauda epididymidal spermatozoa. Selective inhibition of PHGPx, SOD, or CAT did not change this picture. The higher susceptibility of cauda epididymidal spermatozoa to radicals is discussed in relation to the diverse enzymatic activities, vitamin E content, and peroxidative response. These factors are correlated with the different stages of sperm cell maturation, which are characterized-from caput to cauda epididymidis-by progressive destabilization of the plasma and acrosomal membranes.
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PMID:Antioxidant systems in rat epididymal spermatozoa. 974 22

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is a selenium (Se)-dependent glutathione peroxidase. It is reported that the relative PHGPx mRNA levels are much higher in the testis than in the other tissues. We have analyzed the existence and structure of the PHGPx mRNA in rat sperm and the changes in the level of the PHGPx mRNA after feeding with Se-deficient diets. We used 8-wk-old male Wistar strain rats given Se-adequate feed (control group, n = 5) and Se-deficient diets with marginal levels of Se (0.03 ppm or less) (Se-deficient group, n = 5) for 4 wk. The existence and level of the PHGPx mRNA in the cauda epididymal sperm, testis, and liver from the Se-adequate rats were analyzed by the reverse transcription-polymerase chain reaction and the Southern blotting method. As a result, the existence of the PHGPx mRNA was demonstrated in the cauda epididymal sperm as well as in the testis and liver. Moreover, the subtype of the PHGPx mRNA in the rat sperm was the mitochondrial-type mRNA, which included a region corresponding to the mitochondrial transfer leader sequence. These results imply that the intracellular localization of PHGPx may be regulated by the transcription level. On the other hand, there was no significant difference between the control group and the Se-deficient group in the Se level of the cauda epididymal sperm and the level of the PHGPx mRNA. In conclusion, it has been demonstrated that the PHGPx mRNA exists in rat sperm for the first time. The analysis of the PHGPx mRNA in the sperm would be a useful tool for investigating the disfunction caused by the disorder of the level or structure of the PHGPx in the sperm.
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PMID:Analysis of the phospholipid hydroperoxide glutathione peroxidase mRNA in the rat spermatozoon and effect of selenium deficiency on the mRNA. 1104 1

Selenium (Se) and selenoproteins such as glutathione peroxidases are necessary for the proper development and fertilizing capacity of sperm cells. Phospholipid hydroperoxide glutathione peroxidase (PHGPx, E.C. 1.11.1.12) is a monomeric seleno-enzyme present in different mammalian tissues in soluble and bound form. Its function, like the other glutathione peroxidases, was originally viewed as a protective role against hydroperoxides, but direct and indirect evidence indicates that it has additional regulatory roles. PHGPx is present in testis cells and sperm cells, and its appearance is hormone regulated. We present here biochemical data, which clearly indicate that the enzyme specific activity in rat is age-dependent during the life-span monitored (from 36 to 365 days), with a maximum at 3 months of age in the testis germ cells and at 6 months of age in the isolated epididymal sperm cells. Western blotting and immunocytochemical analysis by means of anti-PHGPx antibodies show the different distribution and the strong binding of PHGPx in the testes and sperm cell subcellular compartments (nucleus, acrosome, mitochondria and residual bodies) of rats of different age. The presence of the protein exhibits in the testis cells a pattern different from that of the catalytic activity, with a maximum at 6 months of age. The subcellular distribution of PHGPx is qualitatively, but not quantitatively, unchanged during ageing. These different behaviours are compared and discussed.
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PMID:Enzymatic and immunochemical evaluation of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in testes and epididymal spermatozoa of rats of different ages. 1190 56

The lipid metabolism in sperm cells is important both for energy production and for cell structure. A special composition of membrane phospholipids, rich in polyunsaturated fatty acids (PUFA), and the different composition of sperm and immature germ cell membrane are described and discussed. Testis germ cells as well as epididymal maturing spermatozoa are endowed with enzymatic and non-enzymatic scavenger systems to prevent lipoperoxidative damage. Catalase, superoxide dismutase, and glutathione-dependent oxidoreductases are present in variable amounts in the different developmental stages. Phospholipid hydroperoxide glutathione peroxidase (PHGPx) activity and roles in caput and cauda epididymal sperm cells are discussed. Also seminal plasma has a highly specialized scavenger system that defends the sperm membrane against lipoperoxidation and the degree of PUFA insaturation acts to achieve the same goal. Systemic predisposition and a number of pathologies can lead to an anti-oxidant/pro-oxidant disequilibrium. Scavengers, such as glutathione can be used to treat these cases as they can restore the physiological constitution of PUFA in the cell membrane.
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PMID:Polyunsaturated fatty acids of germ cell membranes, glutathione and blutathione-dependent enzyme-PHGPx: from basic to clinic. 1202 Jul 83

The protective effect of ginseng intestinal metabolite-I (GIM-I) against doxorubicin-induced testicular toxicity was investigated in 5-week-old ICR male mice. GIM-I was administered orally to mice at a dose of 50 mg/kg daily for 4 weeks. From the second week, doxorubicin was coadministered intraperitoneally to the animals at a dose of 3 mg/kg once a week for 3 weeks (a total of 9 mg/kg). The body weight, spermatogenic activities (Sertoli cell, repopulation, and epididymal indices), and serum levels of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) were significantly decreased by doxorubicin treatment (P<0.01), while the combined treatment of GIM-I with doxorubicin resulted in parameters similar to the control. In the testes of doxorubicin-treated animals, almost all of the germ cells disappeared and were replaced by fibrinoid debris in the seminiferous tubules. Germ cell injury was significantly attenuated by GIM-I coadministration. The mRNA for phospholipid hydroperoxide glutathione peroxidase (PHGPx), a testis-specific antioxidant, was greatly decreased by doxorubicin treatment, and less decreased with GIM-I coadministration. These findings indicate that GIM-I may be partially protective against doxorubicin-induced testicular toxicity.
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PMID:Ginseng intestinal metabolite-I (GIM-I) reduces doxorubicin toxicity in the mouse testis. 1212 3

Phospholipid hydroperoxide glutathione peroxidase (PHGPx, 20 kDa) and sperm nuclei glutathione peroxidase (snGPx, 34 kDa) are two selenoproteins present in mammalian testis and epididymal spermatozoa. They originate from the differential splicing of the PHGPx gene and appear to play important roles in sperm physiology. To determine the stages of spermatogenesis in which they are present, we compared the expression pattern of these two enzymes in highly purified populations of germ cells during specific phases of differentiation. In Northern and Western blotting experiments, both PHGPx transcript and protein were markedly expressed in pachytene spermatocytes and round spermatids. In contrast, the testis-specific snGPx was detected at both the mRNA and protein level only in haploid round spermatids. Accordingly, the developmental analysis of testicular RNAs from rats of different ages first revealed the appearance of PHGPx and snGPx transcripts at Day 20 and Day 30, respectively. Furthermore, both meiotic and postmeiotic cells contained catalytically active PHGPx/snGPx, with higher activity in the haploid cells. The intracellular distribution of PHGPx in mitochondria and nuclei of meiotic cells was demonstrated by immunocytochemical electron microscopy and Western blotting. These findings provide evidence that the PHGPx gene is differentially spliced during the meiotic prophase and haploid cell phases of spermatogenesis.
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PMID:Differential splicing of the phospholipid hydroperoxide glutathione peroxidase gene in diploid and haploid male germ cells in the rat. 1253 3

Sperm mitochondria undergo remodeling during posttesticular maturation that includes extensive disulfide cross-linking of proteins of the outer membrane to form the insoluble mitochondrial capsule. The relationship of these changes to mitochondrial function in mature gametes is unclear. The phospholipid hydroperoxide glutathione peroxidase (GPX4; also termed PHGPx) represents a major disulfide bond-stabilized protein of the mitochondrial capsule, and it is readily released by disulfide-reducing agents. However, in addition to GPX4, we detected a second major protein of 26 kDa (MP26) that was eluted from purified hamster sperm tails by the disulfide-reducing agent dithiothreitol. The objectives of the present study were to identify and characterize MP26 and to explore its potential role in mitochondrial function. Proteomic analysis of MP26 by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) identified 14 peptides with sequence identity to a member of the short-chain dehydrogenase/reductase superfamily termed P26h, which was implicated previously in hamster sperm-zona binding, and with high sequence similarity to mouse lung carbonyl reductase. Indirect immunofluorescence localized MP26 to the midpiece, and two-dimensional PAGE and immunoblot analysis identified a single MP26 isoform of pI 9.0. Immunoblot analyses of cauda epididymal fluid and of purified sperm plasma membranes and mitochondria revealed the exclusive localization of MP26 to the mitochondrial fraction. These data indicate that MP26 does not function in zona binding; instead, like GPX4, it may be associated with the mitochondrial capsule and play an important role in sperm mitochondrial function.
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PMID:Identification of a hamster sperm 26-kilodalton dehydrogenase/reductase that is exclusively localized to the mitochondria of the flagellum. 1668 46

Phospholipid hydroperoxide glutathione peroxidase (GPx4) is an intracellular antioxidant enzyme that directly reduces peroxidized phospholipids. GPx4 is strongly expressed in the mitochondria of testis and spermatozoa. We previously found a significant decrease in the expression of GPx4 in spermatozoa from 30% of infertile human males diagnosed with oligoasthenozoospermia (Imai, H., Suzuki, K., Ishizaka, K., Ichinose, S., Oshima, H., Okayasu, I., Emoto, K., Umeda, M., and Nakagawa, Y. (2001) Biol. Reprod. 64, 674-683). To clarify whether defective GPx4 in spermatocytes causes male infertility, we established spermatocyte-specific GPx4 knock-out mice using a Cre-loxP system. All the spermatocyte-specific GPx4 knock-out male mice were found to be infertile despite normal plug formation after mating and displayed a significant decrease in the number of spermatozoa. Isolated epididymal GPx4-null spermatozoa could not fertilize oocytes in vitro. These spermatozoa showed significant reductions of forward motility and the mitochondrial membrane potential. These impairments were accompanied by the structural abnormality, such as a hairpin-like flagella bend at the midpiece and swelling of mitochondria in the spermatozoa. These results demonstrate that the depletion of GPx4 in spermatocytes causes severe abnormalities in spermatozoa. This may be one of the causes of male infertility in mice and humans.
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PMID:Depletion of selenoprotein GPx4 in spermatocytes causes male infertility in mice. 1978 53


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