Differential Expression of Genes Encoding Constitutive and Inducible 20S Proteasomal Core Subunits in the Testis and Epididymis of Theophylline- or 1,3-Dinitrobenzene-Exposed Rats1

Transcriptome-based analysis of the toxic effects of aluminum chloride exposure on spermatocytes

Aluminum chloride (AlCl3) exposure is pervasive in our daily lives. Numerous studies have demonstrated that exposure to AlCl3 can lead to male reproductive toxicity. However, the precise mechanism of action remains unclear. The objective of this study is to investigate the mechanism of aluminum-induced toxicity by analyzing the alterations in the global transcriptome gene profile of mouse spermatocytes (GC-2spd cells) exposed to AlCl3. GC-2spd cells were exposed to concentrations of 0, 1, 2, and 4 mM AlCl3, and high-throughput mRNA-seq was performed to investigate the changes in the transcriptome after exposure to 4 mM AlCl3. Our findings indicate that exposure to AlCl3 led to an increase in oxidative stress, disrupted glutathione metabolism, reduced cell viability, and altered gene expression in mouse spermatocytes. Gene enrichment analysis revealed that the differentially expressed genes (DEGs) were associated with various biological functions such as mitochondrial inner membrane, response to oxidative stress. Furthermore, these DEGs were found to be enriched in pathways including proteasome, glutathione metabolism, oxidative phosphorylation, and Hif-1 signaling pathway. Real-time PCR and western blot were employed to validate the expression alterations of pivotal genes, and the outcomes exhibited concordance with the mRNA-seq findings. This study provides a theoretical basis for revealing the potential mechanism of male reproductive toxicity caused by aluminum exposure.

Biology of the Extracellular Proteasome

Proteasomes are traditionally considered intracellular complexes that play a critical role in maintaining proteostasis by degrading short-lived regulatory proteins and removing damaged proteins. Remarkably, in addition to these well-studied intracellular roles, accumulating data indicate that proteasomes are also present in extracellular body fluids. Not much is known about the origin, biological role, mode(s) of regulation or mechanisms of extracellular transport of these complexes. Nevertheless, emerging evidence indicates that the presence of proteasomes in the extracellular milieu is not a random phenomenon, but rather a regulated, coordinated physiological process. In this review, we provide an overview of the current understanding of extracellular proteasomes. To this end, we examine 143 proteomic datasets, leading us to the realization that 20S proteasome subunits are present in at least 25 different body fluids. Our analysis also indicates that while 19S subunits exist in some of those fluids, the dominant proteasome activator in these compartments is the PA28α/β complex. We also elaborate on the positive correlations that have been identified in plasma and extracellular vesicles, between 20S proteasome and activity levels to disease severity and treatment efficacy, suggesting the involvement of this understudied complex in pathophysiology. In addition, we address the considerations and practical experimental methods that should be taken when investigating extracellular proteasomes. Overall, we hope this review will stimulate new opportunities for investigation and thoughtful discussions on this exciting topic that will contribute to the maturation of the field.

Beyond cells: The extracellular circulating 20S proteasomes

Accumulating evidence arising from numerous clinical studies indicate that assembled and functional 20S proteasome complexes circulate freely in plasma. Elevated levels of this core proteolytic complex have been found in the plasma of patients suffering from blood, skin and solid cancers, autoimmune disorders, trauma and sepsis. Moreover, in various diseases, there is a positive correlation between circulating 20S proteasome (c20S) levels and treatment efficacy and survival rates, suggesting the involvement of this under-studied c20S complex in pathophysiology. However, many aspects of this system remain enigmatic, as we still do not know the origin, biological role or mechanisms of extracellular transport and regulation of c20S proteasomes. In this review, we provide an overview of the current understanding of the c20S proteasome system and discuss the remaining gaps in knowledge.

Semen Parameters of Fertile Guinea Pigs (Cavia porcellus) Collected by Transrectal Electroejaculation

Simple Summary

The guinea pig is an important livestock species in some South American countries. Peruvian guinea pig exports are still increasing since 2000. Peru has made genetic improvements on the species since 1986. However, there are few advances in reproductive biotechnology. Thus, there is a lack of information about harmless, efficient semen collection techniques in the species. Consequently, the selection of fertile males takes a long time due to the absence of validated seminal parameter standards. For that reason, it is necessary to set semen reference values through an objective electroejaculation technique for guinea pigs. This study describes semen parameters of fertile males and validates a novel semen collection technique for the species. These values will serve as a reference to detect infertile males and to select the best males for breeding purposes, improving the reproductive performance on farms.

Abstract

The guinea pig, as a livestock species, is still developing and growing throughout Peru and neighboring countries, as reflected by its increasing export since 2000. However, the selection of proven fertile males is tedious due to the absence of seminal parameter standards and the lack of safe semen collection techniques. Thus, pregnancy detection or live births are required for males’ selection. The purpose of this study was to describe the qualitative and quantitative semen parameters of fertile guinea pig males, to set reference values, and to validate a novel electroejaculation technique for the species. Semen was collected at weekly intervals from sixteen fertile males. Four transrectal electroejaculations were performed per male with 95% successful collections, yielding 39 viable semen samples. Seminal characteristics were as follows: pH 7.0 ± 0.13; ejaculate volume 0.67 ± 0.55 mL; sperm motility 90.81 ± 6.64%; sperm concentration 36.7 ± 28.41 × 106 sperm/mL; sperm count 20.09 ± 17.56 × 106 sperm/ejaculate; percentage of abnormal morphology 18.26 ± 8.52%; and percentage ubiquitinated spermatozoa 5.57 ± 6.28%. These values will serve as a reference to detect best breeding and infertile males rapidly. The described techniques are reproducible by commercial producers.

Copy-number variation introduced by long transgenes compromises mouse male fertility independently of pachytene checkpoints

Long transgenes are often used in mammalian genetics, e.g., to rescue mutations in large genes. In the course of experiments addressing the genetic basis of hybrid sterility caused by meiotic defects in mice bearing different alleles of Prdm9, we discovered that introduction of copy-number variation (CNV) via two independent insertions of long transgenes containing incomplete Prdm9 decreased testicular weight and epididymal sperm count. Transgenic animals displayed increased occurrence of seminiferous tubules with apoptotic cells at 18 days postpartum (dpp) corresponding to late meiotic prophase I, but not at 21 dpp. We hypothesized that long transgene insertions could cause asynapsis, but the immunocytochemical data revealed that the adult transgenic testes carried a similar percentage of asynaptic pachytene spermatocytes as the controls. These transgenic spermatocytes displayed less crossovers but similar numbers of unrepaired meiotic breaks. Despite slightly increased frequency of metaphase I spermatocytes with univalent chromosome(s) and reduced numbers of metaphase II spermatocytes, cytological studies did not reveal increased apoptosis in tubules containing the metaphase spermatocytes, but found an increased percentage of tubules carrying apoptotic spermatids. Sperm counts of subfertile animals inversely correlated with the transcription levels of the Psmb1 gene encoded within these two transgenes. The effect of the transgenes was dependent on sex and genetic background. Our results imply that the fertility of transgenic hybrid animals is not compromised by the impaired meiotic synapsis of homologous chromosomes, but can be negatively influenced by the increased expression of the introduced genes.

Phosphodiesterase Inhibitors (PDE Inhibitors) and Male Reproduction

The nonspecific PDE inhibitors, particularly the methylxanthines: caffeine, pentoxifylline (PTX), and theophylline, are known to stimulate sperm motility in vitro and have been used to treat sperm prior to insemination. The in vivo effects are less dramatic. A beneficial effect of caffeine, which is a constituent of some medications, remains controversial. Very high doses of caffeine do have negative effects on fertility endpoints in men and experimental species. The specific PDE5 inhibitors, particularly sildenafil and tadalafil, are prescribed for erectile dysfunction, as well as pulmonary hypertension, lower urinary tract symptoms, and premature ejaculation. PDE5 is expressed throughout the contractile tissues of the male reproductive tract, generally increasing contractility. Some PDE5 inhibitors tend to increase circulating testosterone levels somewhat. For short-term exposure consistent with use prior to intercourse, there appears to be minimal effects on semen quality. Several large, randomized controlled trials (RCTs) in healthy men have not found adverse effects of long-term use of these drugs on semen quality. RCTs in infertile men have demonstrated a modest increase in semen quality. Animal studies at human equivalent doses (HED) have produced similar results in young males, but a study in aging male rats found progressive decreases in epididymal sperm quality accompanied by consistent degeneration of the seminal tubules suggesting that studies in older men might be warranted. A concerning study in mice found lower fertilization rates in males treated with HED of sildenafil and mated the next day to untreated females than for control males. Fertility studies in humans are needed.

Genomic and proteomic analyses of 1,3-dinitrobenzene-induced testicular toxicity in Sprague-Dawley rats

1,3-Dinitrobenzene (DNB) is an industrial intermediate and testicular toxicant that has been shown to target Sertoli cells. The mechanism of action of DNB in the testis, however, is unclear. To investigate global alterations in gene or protein expression during testicular toxicity, testes from rats treated orally with DNB were subjected to microarray and two-dimensional gel electrophoresis (2-DE) analyses. Histopathological abnormalities were detected in the testes of the DNB-treated rats. Microarray analysis revealed that, during early testicular toxicity, several genes involved in apoptosis, germ cell/Sertoli cell junction, and tight junction signaling pathways were differentially expressed. Based on 2-DE analysis, 36 protein spots showing significantly different expression during early testicular toxicity were selected and identified. Network analysis of the identified proteins revealed that these proteins are associated with cellular development or reproductive system diseases. Collectively, these data will help clarify the molecular mechanism underlying testicular toxicity in DNB-exposed rats.

A comparative study of protein carbonylation and mitochondrial dysfunction using the neurotoxicants 1,3-dinitrobenzene, 3-nitropropionic acid, and 3-chloropropanediol

This comparative evaluation of neurotoxicants previously identified as models of chemical-induced mitochondrial dysfunction and energy deprivation demonstrated that subtoxic concentrations of 1,3-dinitrobenzene (1,3-DNB), 3-nitropropionic acid (3-NPA), and 3-chloropropanediol (3-CPD) each led to concentration-dependent loss of the mitochondrial membrane potential (ΔΨm) associated with similar patterns of protein carbonylation. Subtoxic concentrations of each neurotoxicant were determined by measuring DI TNC1 cell viability using the MTS cell proliferation assay. Although exposure 1 μM, 10 μM, and 100 μM concentrations of each toxicant did not result in loss of cell viability after 48 h, exposure to each toxicant at these concentrations led to concentration-dependent loss of tetramethyl rhodamine methyl ester (TMRM) fluorescence over the same exposure period. Preincubation with the antioxidant, deferoxamine, was effective in preventing loss of TMRM flurorescence. Through the combined use of two-dimensional polyacrylamide gel electrophoresis (2D PAGE) and Oxyblot analysis, this study demonstrated that exposure to each toxicant resulted in the formation of distinctly similar patterns of protein carbonylation comprised of specific proteins identified with tandem MS/MS. Our results provide insight as to how exposure to different neurotoxicants that enhance oxidative stress may, in fact, lead to mitochondrial injury and subsequent toxicity through selective, yet shared, pathways of protein modification by oxidative carbonylation.

Potential new targets involved in 1,3-dinitrobenzene induced testicular toxicity

1,3-Dinitrobenzene (DNB) causes testicular injury, particularly to Sertoli cells, and induces apoptosis in the surrounding germinal cells in rodents; however, the mechanisms causing this toxicity are poorly understood. Our studies, using standard and molecular tools, were conducted to better understand the pathogenesis of the testicular effects. Four daily oral doses of 0.1-8mg/kg/day caused marked testicular lesions in rats from 4mg/kg/day. Global transcriptomics revealed cell cycle and cell death as the major biological processes affected with the expression of genes associated with cell cycle progression ("mitotic roles of polo-like kinase") being particularly altered. In a single dose time course study (4mg/kg), no adverse changes were recorded; however, in contrast to the data from the multiple dose study, plasma testosterone and testicular steroidogenesis-related gene expression were affected. These steroid hormone effects were confirmed in vitro using the H295R steroidogenesis assay. With this global approach we show that DNB not only induces apoptosis and interferes with cell cycle in the testes but that DNB can also modulate steroid hormone biosynthesis, suggesting an interference with the endocrine system. However, the contribution of the endocrine changes to the severe testicular lesions is presently unknown and requires further investigation.

Preservation of ranking order in the expression of human Housekeeping genes

Housekeeping (HK) genes fulfill the basic needs for a cell to survive and function properly. Their ubiquitous expression, originally thought to be constant, can vary from tissue to tissue, but this variation remains largely uncharacterized and it could not be explained by previously identified properties of HK genes such as short gene length and high GC content. By analyzing microarray expression data for human genes, we uncovered a previously unnoted characteristic of HK gene expression, namely that the ranking order of their expression levels tends to be preserved from one tissue to another. Further analysis by tensor product decomposition and pathway stratification identified three main factors of the observed ranking preservation, namely that, compared to those of non-HK (NHK) genes, the expression levels of HK genes show a greater degree of dispersion (less overlap), stableness (a smaller variation in expression between tissues), and correlation of expression. Our results shed light on regulatory mechanisms of HK gene expression that are probably different for different HK genes or pathways, but are consistent and coordinated in different tissues.

Developmental expression of p97/VCP (Valosin-containing protein) and Jab1/CSN5 in the rat testis and epididymis

BACKGROUND

The ubiquitin proteasome system (UPS) is a key player in regulating many cellular processes via proteasomal degradation of ubiquitinated proteins. Recently published data show that Jab1/CSN5 interacts with p97/VCP and controls the ubiquitination status of proteins bound to p97/VCP in mouse and human cells. However, coexpression of p97/VCP and Jab1/CSN5 in the developing rat testis and epididymis has not previously been studied.

METHODS

Testicular and epididymal tissues from 5-, 15-, 30-, and 60-day-old rats were examined by immunohistochemistry and Western blotting. Colocalisation of proteins was determined by immunofluorescence microscopy.

RESULTS

In the 5-day-old rat testis, p97/VCP and Jab1/CSN5 were specifically expressed in gonocytes. The expression of p97/VCP and Jab1/CSN5 significantly increased at day 15 and was found in spermatogonia, Sertoli cells and spermatocytes. In 30- and 60-day-old rat testes, p97/VCP indicated moderate to strong expression in Sertoli cells, spermatogonia, round and elongating spermatids. However, moderate to weak expression was observed in spermatocytes. Jab1/CSN5 showed strong expression in spermatogonia and spermatocytes, while relatively moderate expression was observed in round and elongating spermatids in 30- and 60-day-old rat testes. In contrast, in the epididymis, the expression of both proteins gradually increased from 5 to 60 days of age. After rats reached 2 weeks of age, the expression of both proteins was mostly restricted to the basal and principal cells of the caput epididymis.

CONCLUSIONS

Our study suggests that p97/VCP and Jab1/CSN5 could be an important part of the UPS in the developing rat testis and epididymis and that both proteins may be involved in the regulation of spermatogenesis and epididymal epithelial functions.

Sperm proteasome and fertilization

The omnipresent ubiquitin–proteasome system (UPS) is an ATP-dependent enzymatic machinery that targets substrate proteins for degradation by the 26S proteasome by tagging them with an isopeptide chain composed of covalently linked molecules of ubiquitin, a small chaperone protein. The current knowledge of UPS involvement in the process of sperm penetration through vitelline coat (VC) during human and animal fertilization is reviewed in this study, with attention also being given to sperm capacitation and acrosome reaction/exocytosis. In ascidians, spermatozoa release ubiquitin-activating and conjugating enzymes, proteasomes, and unconjugated ubiquitin to first ubiquitinate and then degrade the sperm receptor on the VC; in echinoderms and mammals, the VC (zona pellucida/ZP in mammals) is ubiquitinated during oogenesis and the sperm receptor degraded during fertilization. Various proteasomal subunits and associated enzymes have been detected in spermatozoa and localized to sperm acrosome and other sperm structures. By using specific fluorometric substrates, proteasome-specific proteolytic and deubiquitinating activities can be measured in live, intact spermatozoa and in sperm protein extracts. The requirement of proteasomal proteolysis during fertilization has been documented by the application of various proteasome-specific inhibitors and antibodies. A similar effect was achieved by depletion of sperm-surface ATP. Degradation of VC/ZP-associated sperm receptor proteins by sperm-borne proteasomes has been demonstrated in ascidians and sea urchins. On the applied side, polyspermy has been ameliorated by modulating sperm-associated deubiquitinating enzymes. Diagnostic and therapeutic applications could emerge in human reproductive medicine. Altogether, the studies on sperm proteasome indicate that animal fertilization is controlled in part by a unique, gamete associated, extracellular UPS.

Proteomic identification of carbonylated proteins in 1,3-dinitrobenzene neurotoxicity

This study demonstrated that 1,3-dinitrobenzene-induced (1,3-DNB) oxidative stress led to the oxidative carbonlyation of specific protein targets in DI TNC1 cells. 1,3-DNB-induced mitochondrial dysfunction, as indicated by loss of tetramethyl rhodamine methyl ester (TMRM) fluorescence, was initially observed at 5h and coincided with peak reactive oxygen species (ROS) production. ROS production was inhibited in cells pre-treated with the mitochondrial permeability transition (MPT) inhibitor, bonkrekic acid (BkA). Pre-incubation with the antioxidant deferoxamine inhibited loss of TMRM fluorescence until 24h after initial exposure to 1,3-DNB. Two-dimensional polyacrylamide gel electrophoresis (2D PAGE) and subsequent Oxyblot analysis were used to determine if 1,3-DNB exposure led to the formation of protein carbonyls. Exposing DI TNC1 cells to 1,3-DNB led to marked protein carbonylation 45 min following initial exposure. Pre-treatment with deferoxamine or Trolox reduced the intensity of protein carbonylation in DI TNC1 cells exposed to 1mM 1,3-DNB. Tandem MS/MS performed on protein samples isolated from 1,3-DNB-treated cells revealed that specific proteins within the mitochondria, endoplasmic reticulum (ER), and cytosol are targets of protein carbonylation. The results presented in this study are the first to suggest that the molecular mechanism of 1,3-DNB neurotoxicity may occur through selective carbonylation of protein targets found within specific intracellular compartments of susceptible cells.

Sperm proteasomes degrade sperm receptor on the egg zona pellucida during mammalian fertilization

Despite decades of research, the mechanism by which the fertilizing spermatozoon penetrates the mammalian vitelline membrane, the zona pellucida (ZP) remains one of the unexplained fundamental events of human/mammalian development. Evidence has been accumulating in support of the 26S proteasome as a candidate for echinoderm, ascidian and mammalian egg coat lysin. Monitoring ZP protein degradation by sperm during fertilization is nearly impossible because those few spermatozoa that penetrate the ZP leave behind a virtually untraceable residue of degraded proteins. We have overcome this hurdle by designing an experimentally consistent in vitro system in which live boar spermatozoa are co-incubated with ZP-proteins (ZPP) solubilized from porcine oocytes. Using this assay, mimicking sperm-egg interactions, we demonstrate that the sperm-borne proteasomes can degrade the sperm receptor protein ZPC. Upon coincubation with motile spermatozoa, the solubilized ZPP, which appear to be ubiquitinated, adhered to sperm acrosomal caps and induced acrosomal exocytosis/formation of the acrosomal shroud. The degradation of the sperm receptor protein ZPC was assessed by Western blotting band-densitometry and proteomics. A nearly identical pattern of sperm receptor degradation, evident already within the first 5 min of coincubation, was observed when the spermatozoa were replaced with the isolated, enzymatically active, sperm-derived proteasomes. ZPC degradation was blocked by proteasomal inhibitors and accelerated by ubiquitin-aldehyde(UBAL), a modified ubiquitin protein that stimulates proteasomal proteolysis. Such a degradation pattern of ZPC is consistent with in vitro fertilization studies, in which proteasomal inhibitors completely blocked fertilization, and UBAL increased fertilization and polyspermy rates. Preincubation of intact zona-enclosed ova with isolated active sperm proteasomes caused digestion, abrasions and loosening of the exposed zonae, and significantly reduced the fertilization/polyspermy rates after IVF, accompanied by en-mass detachment of zona bound sperm. Thus, the sperm borne 26S proteasome is a candidate zona lysin in mammals. This new paradigm has implications for contraception and assisted reproductive technologies in humans, as well as animals.

Methylxanthines and reproduction

Reproduction is the process by which organisms create descendants. In human reproduction, two kinds of sex cells, or gametes, are involved. Sperm, the male gamete, and egg egg , or ovum ovum Vedi egg , the female gamete, must meet in the female reproductive system to create a new individual and both the female and the male reproductive systems are essential to the occurrence of reproduction. Scientific reports dealing with the effects of methylxanthines on reproduction are mostly centred on the use of these compounds as phosphodiesterase inhibitors that, by maintaining high intracellular levels of cyclic AMP (cAMP) cyclic AMP , will affect the gametes differently. High cAMP levels will sustain sperm sperm maturation while they hold the oocytes in mitotic arrest. Caffeine caffeine , being the methylxanthine most widely consumed by every segment of the population, has been the subject of greatest interest among health professionals and researchers. Conflicting results still seem to characterize the association between male/female caffeine caffeine consumption in adult life and semen quality/fertility fertility , although moderate daily caffeine consumption of levels up to 400-450 mg/day (5.7-6.4 mg/kg/day in a 70-kg adult) do not seem to be associated with adverse effects, i.e. general toxicity, effects on bone status and calcium balance, cardiovascular effects, behavioural changes, increased incidence of cancer, or effects on male fertility. A clear stimulation of egg-laying by the coffee leaf pest Leucoptera coffeella was recently reported, providing support for the hypothesis that caffeine, in a dose-dependent way, in insects stimulates egg-laying, thus leading to the death of coffee trees.

A novel testis-specific GTPase serves as a link to proteasome biogenesis: functional characterization of RhoS/RSA-14-44 in spermatogenesis

We functionally characterized RhoS/RSA-14-44 as a new member of Rho GTPase subfamily in spermatogenesis, which provides a direct link between Rho family GTPase and the proteasome biogenesis.

Most Rho family GTPases serve as key molecular switches in a wide spectrum of biological processes. An increasing number of studies have expanded their roles to the spermatogenesis. Several members of Rho family have been confirmed to be essential for mammalian spermatogenesis, but the precise roles of this family in male reproduction have not been well studied yet. Here we report a surprising function of an atypical and testis-specific Rho GTPase, RSA-14-44 in spermatogenesis. Featured by unique structural and expressional patterns, RSA-14-44 is distinguished from three canonical members of Rho cluster. Thus, we define RSA-14-44 as a new member of Rho GTPases family and rename it RhoS (Rho in spermatogenic cells). RhoS associates with PSMB5, a catalytic subunit of the proteasome, in a series of stage-specific spermatogenic cells. More importantly, RhoS does not directly modulate the cellular proteasome activity, but participates in regulating the stability of “unincorporated” PSMB5 precursors. Meanwhile, our data demonstrate that the activation of RhoS is prerequisite for negatively regulating the stability of PSMB5 precursors. Therefore, our finding uncovers a direct and functional connection between the Rho GTPase family and the pathway of proteasome biogenesis and provide new clues for deciphering the secrets of spermatogenesis.

RT-PCR cytokine study in patients with allergic rhinitis

Allergic rhinitis is an inflammatory reaction of the nasal mucosa, in consequence of an IgE mediated hypersensitive reaction to inhaling allergens, involving different mediators and cytokine cells.

AIM

The purpose of this study was to evaluate the transcriptions for IL-4, IL-5, IL-8 and IFN-gama, particularly important in the nasal allergy process, especially IL-4 and IL-5. For this study we decided to evaluate atopic patients who were free from allergic crises, with the purpose of knowing the cytokine expressions during this period.

MATERIALS AND METHODS

Another prospective and transversal study was carried out, selecting 30 patients, 13 of these patients were pauci-symptomatic and 17 were non atopic. The groups were selected by means of a medical interview, an otolaryngologic clinical exam and allergy skin tests - Prick Test. The cytokines were investigated in fragments of the nasal mucosa, using RT-PCR - chosen because it has good reproducibility and specificity.

RESULTS

IL-5, IL-8, IFN-gama cytokine values were kept homogeneous in relation to the control group. Only IL-4 presented significant statistic differences.

CONCLUSION

Asymptomatic patients with allergic rhinitis presented with normalization of cytokine expression in the nasal mucosa, with exception of IL-4.

Dynamic modularity in protein interaction networks predicts breast cancer outcome

Changes in the biochemical wiring of oncogenic cells drives phenotypic transformations that directly affect disease outcome. Here we examine the dynamic structure of the human protein interaction network (interactome) to determine whether changes in the organization of the interactome can be used to predict patient outcome. An analysis of hub proteins identified intermodular hub proteins that are co-expressed with their interacting partners in a tissue-restricted manner and intramodular hub proteins that are co-expressed with their interacting partners in all or most tissues. Substantial differences in biochemical structure were observed between the two types of hubs. Signaling domains were found more often in intermodular hub proteins, which were also more frequently associated with oncogenesis. Analysis of two breast cancer patient cohorts revealed that altered modularity of the human interactome may be useful as an indicator of breast cancer prognosis.

Análise de citocinas pela RT-PCR em pacientes com rinite alérgica

Rinite alérgica é uma doença que decorre de um processo inflamatório da mucosa nasal conseqüente à reação de hipersensibilidade a alérgenos inalatórios e, eventualmente, alimentares. É mediada por IgE, envolvendo diferentes células, mediadores e citocinas. OBJETIVO: Avaliar as transcrições para as seguintes citocinas: IL-4, IL-5, IL-8 e IFN-gama, particularmente importantes no processo alérgico nasal, principalmente IL-4 e IL-5. Neste estudo, optou-se por avaliar os pacientes atópicos fora das crises alérgicas, com a finalidade de se conhecer as expressões das citocinas neste período. MATERIAL E MÉTODO: Realizou-se um estudo transversal e prospectivo, selecionando-se 30 pacientes, sendo 13 pacientes portadores de rinite alérgica paucissintomáticos e 17 pacientes não-atópicos. Os grupos foram selecionados através da história, do exame clínico otorrinolaringológico e do teste alérgico cutâneo - Prick Test. O perfil das citocinas foi pesquisado nos fragmentos de mucosa nasal, através da RT-PCR semiquantitativa, escolhida por apresentar boa reprodutibilidade e especificidade, utilizando-se como referência o gene da Beta-actina. RESULTADOS: Os valores de IL-5, IL-8, IFN-gama mantiveram-se homogêneos em relação ao grupo controle. A IL-4 apresentou diferença com significância estatística. CONCLUSÃO: Os pacientes alérgicos paucissintomáticos apresentaram normalização da expressão das citocinas na mucosa nasal à exceção de IL-4.

Screening of toxicological properties of 4-methylbenzoic acid by oral administration to rats

Oral toxicity of 4-methylbenzoic acid in male and female Sprague-Dawley rats was profiled through a twenty-eight-day repeated dose toxicity study (the 28-day study) and a screening test for reproductive/developmental toxicities (the reproduction/developmental study) conducted under Organisation for Economic Co-operation and Development (OECD) test guidelines. Daily administration of 4-methylbenzoic acid, at a dose level of 0, 100, 300 or 1,000 mg/kg, did not show any adverse effect on reproductive organs of animals in the 28-day study. In the reproductive/developmental study, however, 1,000 mg/kg/day of the compound reduced epididymal weights and increased incidence of cauda epididymal oligo/azoospermia. While the compound did not affect estrous cycle or mating performances, 1,000 mg/kg of the compound reduced fertility. Furthermore, 300 mg/kg or more of the compound increased pre-implantation loss, which resulted in a decrease in the number of offspring, and reduced body weight gain of the dams during the latter period of gestation. From these results, the no-observed-effect-level (NOEL) for reproductive/developmental toxicities is considered to be 100 mg/kg, whereas 1,000 mg/kg did not show any effect on neonates. In the 28-day study, NOEL is considered to be 300 mg/kg for male and female rats, since 1,000 mg/kg of the compound caused, in both sexes, a few minor changes, such as temporal salivation, a slight increase in food consumption and a moderate increase in blood aspartate aminotransferase (AST) activity. Thus, 4-methylbenzoic acid has the potential for reproductive toxicity, with diverse adverse effects on the epididymis, after repeated administration, observed in the two studies.

Extracellular, circulating proteasomes and ubiquitin - incidence and relevance

The ubiquitin-proteasome system is the major pathway for intracellular protein degradation and is also deeply involved in the regulation of most basic cellular processes. Its proteolytic core, the 20S proteasome, has found to be attached also to the cell plasma membrane and certain observations are interpreted as to suggest that they may be released into the extracellular medium, e.g. in the alveolar lining fluid, epididymal fluid and possibly during the acrosome reaction. Proteasomes have also been detected in normal human blood plasma and designated circulating proteasomes; these have a comparatively low specific activity, a distinct pattern of subtypes and their exact origin is still enigmatic. In patients suffering from autoimmune diseases, malignant myeloproliferative syndromes, multiple myeloma, acute and chronic lymphatic leukaemia, solid tumour, sepsis or trauma, respectively, the concentration of circulating proteasomes has been found to be elevated, to correlate with the disease state and has even prognostic significance. Similarly, ubiquitin has been discovered as a normal component of human blood and seminal plasma and in ovarian follicular fluid. Increased concentrations were measured in diverse pathological situations, not only in blood plasma but also in cerebrospinal fluid, where it may have neuroprotective effects. As defective spermatozoa are covered with ubiquitin in the epididymal fluid, extracellular ubiquitination is proposed to be a mechanism for quality control in spermatogenesis. Growing evidence exists also for a participation of extracellular proteasomes and ubiquitin in the fertilization process.

Mechanism of extracellular ubiquitination in the mammalian epididymis

Posttranslational modification by ubiquitination marks defective or outlived intracellular proteins for proteolytic degradation by the 26S proteasome. The ATP-dependent, covalent ligation and formation of polyubiquitin chains on substrate proteins requires the presence and activity of a set of ubiquitin activating and conjugating enzymes. While protein ubiquitination typically occurs in the cell cytosol or nucleus, defective mammalian spermatozoa become ubiquitinated on their surface during post-testicular sperm maturation in the epididymis, suggesting an active molecular mechanism for sperm quality control. Consequently, we hypothesized that the bioactive constituents of ubiquitin-proteasome pathway were secreted in the mammalian epididymal fluid (EF) and capable of ubiquitinating extrinsic substrates. Western blotting indeed detected the presence of the ubiquitin-activating enzyme E1 and presumed E1-ubiquitin thiol-ester intermediates, ubiquitin-carrier enzyme E2 and presumed E2-ubiquitin thiol-ester intermediates and the ubiquitin C-terminal hydrolase PGP 9.5/UCHL1 in the isolated bovine EF. Thiol-ester assays utilizing recombinant ubiquitin-activating and ubiquitin-conjugating enzymes, biotinylated substrates, and isolated bovine EF confirmed the activity of the ubiquitin activating and conjugating enzymes within EF. Ubiquitinated proteins were found to be enriched in the defective bull sperm fraction and appropriate proteasomal deubiquitinating and proteolytic activities were measured in the isolated EF by specific fluorescent substrates. The apocrine secretion of cytosolic proteins was visualized in transgenic mice and rats expressing the enhanced green fluorescent protein (eGFP) under the direction of ubiquitin-C promoter. Accumulation of eGFP, ubiquitin and proteasomes was detected in the apical blebs, the apocrine secretion sites of the caput epididymal epithelia of both the rat and mouse epididymal epithelium, although region-specific differences exist. Secretion of eGFP and proteasomes continued during the prolonged culture of the isolated rat epididymal epithelial cells in vitro. This study provides evidence that the activity of the ubiquitin system is not limited to the intracellular environment, contributing to a greater understanding of the sperm maturation process during epididymal passage.

Success and failure in human spermatogenesis as revealed by teratozoospermic RNAs

We are coming to appreciate that at fertilization human spermatozoa deliver the paternal genome alongside a suite of structures, proteins and RNAs. Although the role of some of the structures and proteins as requisite elements for early human development has been established, the function of the sperm-delivered RNAs remains a point for discussion. The presence of RNAs in transcriptionally quiescent spermatozoa can only be derived from transcription that precedes late spermiogenesis. A cross-platform microarray strategy was used to assess the profile of human spermatozoal transcripts from fertile males who had fathered at least one child compared to teratozoospermic individuals. Unsupervised clustering of the data followed by pathway and ontological analysis revealed the transcriptional perturbation common to the affected individuals. Transcripts encoding components of various cellular remodeling pathways, such as the ubiquitin-proteosome pathway, were severely disrupted. The origin of the perturbation could be traced as far back as the pachytene stage of spermatogenesis. It is anticipated that this diagnostic strategy will prove valuable for understanding male factor infertility.