Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.25.1 (proteasome)
28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have used a rat pachytene spermatocyte cDNA expression library to clone TBP-1 (for tat-binding protein-1; designated rat testis TBP-1 [rtTBP-1]), a new member of the family of putative ATPases associated with the 26S proteasome complex. The 1.63 kb rtTBP-1 cDNA encodes a 49 kDa protein with 99% amino acid identity to human TBP-1 protein. rtTBP-1 protein contains a heptad repeat of six leucine-type zipper fingers at the amino terminal end and highly conserved ATPase and DNA/RNA helicase motifs towards the carboxyl terminal region. Chromatofocusing fractionation of rat testis sucrose extracts demonstrates that the encoded product, recognized by an antiserum raised to the first 196 amino acids of human TBP-1, consists of a protein triplet with a molecular mass range of 52-48 kDa and acidic pI (5.0-5.9). An identical immunoreactive triplet was detected by immunoblotting in extracts of fractionated pachytene spermatocytes, round spermatids and epididymal sperm. In situ hybridization using digoxigenin-labeled antisense RNA probes shows a predominant distribution of specific mRNA in the seminiferous epithelial region occupied by elongating spermatids and primary spermatocytes. Indirect immunofluorescence and immunogold electron microscopy studies show that rtTBP-1 immunoreactive sites colocalize with alpha-tubulin-decorated manchettes of elongating spermatids. In addition, rtTBP-1 immunoreactivity was detected in fibrillar and granular cytoplasmic bodies typically observed in spermatocytes and spermatids as well as in association with paraaxonemal mitochondria and outer dense fibers of the developing spermatid tail. Results of this study indicate that rtTBP-1 is a member of the highly evolutionary conserved TBP-1-like subfamily of putative ATPases, sharing regions of identity-including ATP-binding sites-with several subunits of the 26S proteasome, known to be involved in the ATP-dependent degradation of ubiquitin-conjugated proteins.
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PMID:A protein associated with the manchette during rat spermiogenesis is encoded by a gene of the TBP-1-like subfamily with highly conserved ATPase and protease domains. 926 64

We have previously cloned a cDNA encoding TBP-1, a protein present in the rat spermatid manchette and outer dense fibers of the developing sperm. TBP-1 contains a heptad repeat of six-leucine zipper fingers at the amino terminus and highly conserved ATPase and DNA/RNA helicase motifs toward the carboxyl terminus. TBP-1 is one of the 20 subunits forming the 19S regulatory complex of the 26S proteasome, an ATP-dependent multisubunit protease found in most eukaryotic cells. We now report the isolation of the 26S proteasome from rat testis and sperm tail and its visualization by whole-mount electron microscopy using negative staining. The 26S proteasome from rat testis was fractionated by Sephacryl S-400/Mono-Q chromatography using homogenates suspended in a 10% glycerol-supplemented buffer. Chromatographic fractions were analyzed by immunoblotting using a specific anti-TBP-1 serum. During the purification of Sak57, a keratin filament present in outer dense fibers from epididymal sperm, we detected a substantial amount of 26S proteasomes. Intact 26S proteasomes from rat testis display a rod-shaped particles about 45 nm in length and 11-17 nm in diameter. Each particle consists of a 20S barrel-shaped component formed by four rings (alphabetabetaalpha), capped by two polar 19S regulatory complexes, each identified by an element known as the "Chinese dragon head motif". TBP-1 is an ATPase-containing subunit of the 19S regulatory cap. Rat sperm preparations displayed both dissociated 26S proteasomes and Sak57 filaments. We hypothesize that 26S proteasomes in the perinuclear-arranged manchette are in a suitable location for recognition, sequestration, and degradation of accumulating ubiquitin-conjugated somatic and transient testis-specific histones during spermiogenesis. In the sperm tail, the 26S proteasome may have a role in the remodeling of the outer dense fibers and other tail components during epididymal transit.
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PMID:Structural features of the 26S proteasome complex isolated from rat testis and sperm tail. 1098 18

Ubiquitination of the sperm mitochondria during spermatogenesis has been implicated in the targeted degradation of paternal mitochondria after fertilization, a mechanism proposed to promote the predominantly maternal inheritance of mitochondrial DNA in humans and animals. The identity of ubiquitinated substrates in the sperm mitochondria is not known. In the present study, we show that prohibitin, a highly conserved, 30- to 32-kDa mitochondrial membrane protein, occurs in a number of unexpected isoforms, ranging from 64 to greater than 185 kDa in the mammalian sperm mitochondria, which are the ubiquitinated substrates. These bands bind antiubiquitin antibodies, displaying a pattern consistent with polyubiquitinated "ladders." Immunoprecipitation of sperm extracts with antiprohibitin antibodies followed by probing of the resultant immunocomplexes with antiubiquitin yields a banding pattern identical to that observed by antiprohibitin Western blot analysis. In fact, the presumably nonubiquitinated 30-kDa prohibitin band shows no antiubiquitin immunoreactivity. We demonstrate that ubiquitination of prohibitin occurs in testicular spermatids and spermatozoa. Ubiquitinated prohibitin molecules also accumulate in the defective fractions of ejaculated spermatozoa, which are thought to undergo surface ubiquitination during epididymal passage. In such sperm fractions, ubiquitin also coprecipitates with tubulin and microtubule-associated proteins, presumably contributed by the axonemes of defective, ubiquitinated spermatozoa. The results of the present study suggest that prohibitin is one of the ubiquitinated substrates that makes the sperm mitochondria recognizable by the egg's ubiquitin-proteasome dependent proteolytic machinery after fertilization and most likely facilitates the marking of defective spermatozoa in the epididymis for degradation.
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PMID:Ubiquitination of prohibitin in mammalian sperm mitochondria: possible roles in the regulation of mitochondrial inheritance and sperm quality control. 1264 88

A long-standing problem in epididymal physiology is the fate of unejaculated spermatozoa in the cauda epididymidis under conditions such as congenital absence of the vas deferens, long-term vasectomy, or castration. There is no convincing evidence for significant absorption of spermatozoa, defective or otherwise, by spermiophagy or dissolution in the epididymis of normal animals. Spermiophagy by epithelial cells or intraluminal macrophages may take place if the duct ruptures and granulomas form (e.g., after experimental ligation), although there is no quantitative information on the rate of sperm removal by this means. In one animal model (the rabbit), the epididymis is unusually resistant to granuloma formation and has provided unique insights into a phenomenon that is suggested to be present in all species. Spermatozoa retained in the rabbit cauda epididymidis by placing ligatures on the vas deferens and corpus epididymidis degenerate after several weeks but do not decrease significantly in numbers. After castration, however, they die very rapidly and >90% disappear. It is hypothesized that, in the normal androgen-maintained epididymis, degradative pathways are present in the luminal fluid that are constitutively inhibited by survival signals emanating from the epithelium. In the absence of androgen, the intraluminal mileau changes and death signals predominate that activate degradative pathways via the ubiquitin-proteasome system, DNAses, etc., to mediate dissolution of sperm organelles and nucleoprotein. It is suggested that the latter condition is the default situation and is only prevented by the stimulatory action of androgens on the epididymal epithelium.
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PMID:Sperm survival versus degradation in the Mammalian epididymis: a hypothesis. 1521 93

The mouse USP8/mUBPy gene codifies a deubiquitinating enzyme expressed preferentially in testis and brain. While the ubiquitin-specific processing proteases (UBPs) are known to be important for the early development in invertebrate organisms, their specific functions remain still unclear in mammals. Using specific antibodies, raised against a recombinant mUBPy protein, we studied mUBPy in mouse testis. The mUBPy is expressed exclusively by the germ cell component and is maintained in epididymal spermatozoa. The enzyme is functionally active, being able to detach ubiquitin moieties from endogenous protein substrates. Protein interaction assays showed that sperm UBPy interacts with MSJ-1, the sperm-specific DnaJ protein evolutionarily conserved for spermiogenesis. Immunocytochemistry revealed that mUBPy shares with MSJ-1 the intracellular localization during spermatid cell differentiation; intriguingly, we show here that the proteasomes also locate in mUBPy/MSJ-1-positive sites, such as the cytoplasmic surface of the developing acrosome and the centrosomal region. These colocalization sites are maintained in epididymal spermatozoa. The demonstration of a protein interaction between a deubiquitinating enzyme and a molecular chaperone and the documentation on the proteasomes in both differentiating and mature mouse male germ cells suggest that members of the chaperone and ubiquitin/proteasome systems could cooperate in the fine control of protein quality to yield functional spermatozoa.
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PMID:The deubiquitinating enzyme mUBPy interacts with the sperm-specific molecular chaperone MSJ-1: the relation with the proteasome, acrosome, and centrosome in mouse male germ cells. 1534 53

Sulfasalazine (SASP) has been reported to depress the fertility in men and experimental male animals, but the fundamental mechanisms of infertility caused by SASP are still unknown. This study was designed to investigate the mechanisms of infertility in rats treated with SASP at a dose of 600 mg/kg for 28 days, including monitoring of sperm motility using computer associated sperm analysis system and acrosome reaction by FITC-concanavalin A lectin staining. The sperm motility and acrosome reaction, which are important for fertilization, were significantly reduced by SASP. Furthermore, to investigate the molecular mechanisms of infertility induced by SASP, mRNA expression analysis in the testes was performed using cDNA microarray as a first screening. It was revealed that CD59, which is located on the acrosomal membrane and is known to be important for the reproductive function of sperm, was affected in the testes; this was also confirmed by real-time PCR analysis, but the spermatogenesis-related genes examined in this study were not affected. Therefore, we focused on CD59 and two other acrosome membrane related-genes: MCP and DAF. CD59, MCP, and DAF in the epididymides of SASP-treated rats were significantly decreased as assessed by real-time RT-PCR analysis and additionally, the expression of CD59 protein was found to be decreased by Western blotting. These results allowed us to hypothesize that the suppression of epididymal acrosomal membrane proteins synthesis with their consequent reduced incorporation to the sperm membrane leads to a depressed sperm motility and acrosome reaction, and thereby leads to infertility in SASP treated male rats.
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PMID:Effects of sulfasalazine on sperm acrosome reaction and gene expression in the male reproductive organs of rats. 1562 86

The contraceptive efficacy and toxicological screening of the two principal compounds, MCP I and ECP I, isolated from the seeds of Carica papaya, in male albino rats at the standardized dose regimen, at 50 mg/kg b.w./day, for a period of 360 days and up to 90 days of treatment withdrawal have been reported. The body and organ weights, cauda epididymal sperm characteristics, androgen sensitive tissue biochemistry, reactive oxygen species and anti-oxidant defense system in the cauda epididymal microenvironment, histology and ultrastructure of testis and cauda epididymis, histology of seminal vesicle and prostate, toxicological investigations through routine hematology and serum clinical chemistry, sexual behaviour and fertility index have been studied. The results revealed that oral administration of MCP I and ECP I were equally effective, exhibiting complete inhibition of sperm motility following 90 days of treatment that coincided with a gradual and significant decline in cauda epididymal sperm density, percent viable spermatozoa and significant increase in sperm anomalies. Histology of testis of treated animals revealed degenerated germinal epithelium, vacuolization in Sertoli cells and proliferating germ cells and disturbances in spermatid differentiation. Spermatogonial stem cell reserves and Leydig cells appeared normal. Ultrastructure of the testis revealed vacuolization in the Sertoli cells and germ cells, loss of cytoplasmic characteristics in the Sertoli cells, nuclear degeneration and mitochondrial vacuolization in spermatocytes and spermatids. Leydig cells exhibited steroidogenic features. Cauda epididymis showed normal epithelial cell function. Absence of spermatozoa or disruption of spermatozoa clusters in the lumen were evident. Ultrastructure of cauda epididymis revealed normal secretory activity. Morphology of seminal vesicle and prostate of the treated animals were comparable to control animals. Serum testosterone, tissue biochemical and toxicological parameters remained unaffected. Fertility test revealed 100% efficacy. All the altered parameters showed sign of recovery following 90 days of treatment withdrawal. It is concluded that both MCP I and ECP I are equally effective in terms of contraceptive efficacy which is likely reversible and without adverse side effects.
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PMID:Efficacy trial on the purified compounds of the seeds of Carica papaya for male contraception in albino rat. 1580 97

Lipoxygenases (LOXs) are a family of enzymes capable of peroxidizing phospholipids. A member of the LOX family of enzymes, 15-LOX, participates in the degradation of mitochondria and other organelles within differentiating red blood cells, the reticulocytes. The present study provides biochemical and immunocytochemical evidence for the presence of 15-LOX in the sperm cytoplasmic droplet (CD). Testicular, epididymal and ejaculated spermatozoa were evaluated for the presence of 15-LOX using an affinity-purified immune serum raised against a synthetic peptide corresponding to the C-terminal sequence of rabbit reticulocyte 15-LOX. Western blotting revealed an appropriate single band of approximately 81 kDa in boar spermatozoa but not in boar seminal plasma. When ejaculated boar spermatozoa were subjected to separation on a 45/90% Percoll gradient, 15-LOX co-migrated with the immotile sperm and cellular debris/CD fractions, but not with the motile sperm fraction containing morphologically normal spermatozoa without CDs. Varied levels of 15-LOX were expressed in ejaculated sperm samples from boars with varied semen quality. By immunofluorescence, prominent 15-LOX immunoreactivity was found within the residual body in the testis and within the CDs from caput, corpus and cauda epididymal and ejaculated spermatozoa. Components of the ubiquitin-dependent proteolytic pathway, which is thought to facilitate both spermiogenesis and reticulocyte organelle degradation, were also detected in the sperm CD. These included ubiquitin, the ubiquitin-conjugating enzyme E2, the ubiquitin C-terminal hydrolase PGP 9.5, and various 20S proteasomal core subunits of the alpha- and beta-type. The 15-LOX and various components of the ubiquitin-proteasome pathway were also detected in sperm CDs of other mammalian species, including the human, mouse, stallion and wild babirusa boar. We conclude that 15-LOX is prominently present in the mammalian sperm CD and thus may contribute to spermiogenesis, CD function or CD removal.
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PMID:15-Lipoxygenase is a component of the mammalian sperm cytoplasmic droplet. 1604 59

This study investigated the testicular changes in the rat induced by the nonspecific phosphodiesterase inhibitor, theophylline using magnetic resonance microscopy (MRM) and ubiquitin immunostaining techniques. In vivo T1- and T2-weighted images were acquired at 2 T under anesthesia. Increased signal observed in the theophylline-treated rats suggests that leakage of MRM contrast was occurring. In vivo MRM results indicate that day 16 testis displayed an increased T1-weighted water signal in the area of the seminiferous tubule that decreased by day 32. These findings were validated by histopathology, suggesting that in vivo MRM has the sensitivity to predict changes in testis and epididymal tissues. The participation of the ubiquitin system was investigated, using probes for various markers of the ubiquitin-proteasome pathway. MRM can be used to detect subtle changes in the vascular perfusion of organ systems, and the up-regulation/mobilization of ubiquitin-proteasome pathway may be one of the mechanisms used in theophylline-treated epididymis to remove damaged cells before storage in the cauda epididymis. The combined use of in vivo MRM and subsequent tissue or seminal analysis for the presence of ubiquitin in longitudinal studies may become an important biomarker for assessing testis toxicities drug studies.
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PMID:Reproductive cytotoxicity is predicted by magnetic resonance microscopy and confirmed by ubiquitin-proteasome immunohistochemistry in a theophylline-induced model of rat testicular and epididymal toxicity. 1607 14

Theophylline (THP) and 1,3-dinitrobenzene (DNB) are thought to induce infertility by incapacitating the nurturing Sertoli cells and causing germ cell apoptosis in the testicular seminiferous epithelium, respectively. We hypothesized that THP and DNB exposure would alter the expression of the genes within the ubiquitin-proteasome pathway (UPP), implicated in spermatogenesis and epididymal sperm quality control. Rats were fed 0 or 8000 ppm of THP and necropsied on Days 18, 30, and 42 or administered 0, 2, or 6 mg/kg DNB via oral gavage and necropsied on Day 7. Tissues were collected from the testis and the caput, corpus, and cauda regions of the epididymis for transcriptional profiling by semiquantitative RT-PCR, real-time RT-PCR, and histopathology. Target UPP genes included those encoding for constitutive the 20S proteasomal core subunits Psmb1 (beta1), Psmb2 (beta2), and Psmb5 (beta5); the inducible 20S core subunits Psmb9 (LMP2), Psmb8 (LMP7), and Psmb10 (LMP10); and Ube1 (ubiquitin-activating enzyme E1), Ube2d3 (ubiquitin-conjugating enzyme E2), and Uchl1 (ubiquitin C-terminal hydrolase PGP9.5). Spermatozoa were collected from the cauda epididymis for analysis by light microscopy and flow cytometric evaluation of sperm surface ubiquitin. These data show that reprotoxic exposure alters the tissue-specific expression of UPP genes in the testis and epididymis, which may contribute to the aberrant spermatogenesis and epididymal processing of both normal and defective spermatozoa. Transcriptional profiling and flow cytometric analysis of the UPP thus captures the prodromal effects of reproductive toxicity not captured by conventional histology and functional cytology. Complementing seminal analysis with these measures may be useful in screening drug-induced toxicity or environmental infertility.
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PMID:Differential expression of genes encoding constitutive and inducible 20S proteasomal core subunits in the testis and epididymis of theophylline- or 1,3-dinitrobenzene-exposed rats. 1698 15


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