Regulation of hsp expression during rodent spermatogenesis

Identification of BiP as a temperature sensor mediating temperature-induced germline sex reversal in C. elegans

Sex determination in animals is not only determined by karyotype but can also be modulated by environmental cues like temperature via unclear transduction mechanisms. Moreover, in contrast to earlier views that sex may exclusively be determined by either karyotype or temperature, recent observations suggest that these factors rather co-regulate sex, posing another mechanistic mystery. Here, we discovered that certain wild-isolated and mutant C. elegans strains displayed genotypic germline sex determination (GGSD), but with a temperature-override mechanism. Further, we found that BiP, an ER chaperone, transduces temperature information into a germline sex-governing signal, thereby enabling the coexistence of GGSD and temperature-dependent germline sex determination (TGSD). At the molecular level, increased ER protein-folding requirements upon increased temperatures lead to BiP sequestration, resulting in ERAD-dependent degradation of the oocyte fate-driving factor, TRA-2, thus promoting male germline fate. Remarkably, experimentally manipulating BiP or TRA-2 expression allows to switch between GGSD and TGSD. Physiologically, TGSD allows C. elegans hermaphrodites to maintain brood size at warmer temperatures. Moreover, BiP can also influence germline sex determination in a different, non-hermaphroditic nematode species. Collectively, our findings identify thermosensitive BiP as a conserved temperature sensor in TGSD, and provide mechanistic insights into the transition between GGSD and TGSD.

Testicular expression of heat SHOCK proteins 60, 70, and 90 in cryptorchid horses

Heat shock proteins are the most evolutionarily conserved protein families induced by stressors including hyperthermia. In the context of pathologies of the male reproductive tract, cryptorchidism is the most common genital defect that compromises the reproductive potential of the male because it induces an increase in intratesticular temperature. In equine species, cryptorchidism affects almost 9 % of newborns and few studies have been carried out on the molecular aspects of the retained testis. In this study, the expression pattern of HSP60, 70, and 90 in abdominal and inguinal testes, in their contralateral descended normally testes, and in testes of normal horses were investigated by Western blot and immunohistochemistry. The histomorphological investigation of retained and scrotal testes was also investigated. The seminiferous epithelium of the retained testes showed a vacuolized appearance and displayed a completely blocked spermatogenesis for lacking meiotic and spermiogenetic cells. On the contrary, the contralateral scrotal testes did not show morphological damage and the seminiferous epithelium displayed all phases of the spermatogenetic cycle as in the normal testes. The morphology of Leydig cells was not affected by the cryptorchid state. Western blot and immunohistochemistry evidenced that equine testis (both scrotal and retained) expresses the three investigated HSPs. More in detail, the Western blot evidenced that HSP70 is the more expressed chaperone and that together with HSP90 it is highly expressed in the retained gonad (P < 0.05). The immunohistochemistry revealed the presence of the three HSPs in the spermatogonia of normal and cryptorchid testes. Spermatogonia of retained testes showed the lowest expression of HSP60 and the highest expression of HSP90. Spermatocytes, spermatids of scrotal testes, and the Sertoli cells of retained and scrotal testes did not display HSP60 whereas expressed HSP70 and HSP90. These two proteins were also localized in the nucleus of the premeiotic cells. The Leydig cells displayed the three HSPs with the higher immunostaining of HSP70 and 90 in the cryptorchid testes. The results indicate that the heat stress condition occurring in the cryptorchid testis influences the expression of HSPs.

Genetic variants underlying spermatogenic arrests in men with non-obstructive azoospermia

Spermatogenic arrest is a severe form of non-obstructive azoospermia (NOA), which occurs in 10-15% of infertile men. Interruption in spermatogenic progression at premeiotic, meiotic, or postmeiotic stage can lead to arrest in men with NOA. Recent studies have intensively focused on defining genetic variants underlying these spermatogenic arrests by making genome/exome sequencing. A number of variants were discovered in the genes involving in mitosis, meiosis, germline differentiation and other basic cellular events. Herein, defined variants in NOA cases with spermatogenic arrests and created knockout mouse models for the related genes are comprehensively reviewed. Also, importance of gene panel-based screening for NOA cases was discussed. Screening common variants in these infertile men with spermatogenic arrests may contribute to elucidating the molecular background and designing novel treatment strategies.

Conditional deletion of Hspa5 leads to spermatogenesis failure and male infertility in mice

Heat shock proteins (HSPs) have important roles in different developmental stages of spermatogenesis. The heat shock 70 kDa protein 5 (HSPA5) is an important component of the unfolded protein response that promotes cell survival under endoplasmic reticulum (ER) stress conditions. In this study, we explored the function of HSPA5 in spermatogenesis, by generating a germ cell-specific deletion mutant of the Hspa5 gene (conditional knockout of the Hspa5 gene, Hspa5-cKO) using CRISPR/Cas9 technology and the Cre/Loxp system. Hspa5 knockout resulted in severe germ cell loss and vacuolar degeneration of seminiferous tubules, leading to complete arrest of spermatogenesis, testicular atrophy, and male infertility in adult mice. Furthermore, defects occurred in the spermatogenic epithelium of Hspa5-cKO mice as early as Cre recombinase expression. Germ cell ablation of Hspa5 impaired spermatogonia proliferation and differentiation from post-natal day 7 (P7) to P10, which led to a dramatic reduction of differentiated spermatogonia, compromised meiosis, and led to impairment of testis development and the disruption of the first wave of spermatogenesis. Consistent with these results, single-cell RNA sequencing (scRNA-seq) analysis showed that germ cells, especially differentiated spermatogonia, were dramatically reduced in Hspa5-cKO testes compared with controls at P10, further confirming that HSPA5 is crucial for germ cell development. These results suggest that HSPA5 is indispensable for normal spermatogenesis and male reproduction in mice.

Heat shock protein 101 contributes to the thermotolerance of male meiosis in maize

High temperatures interfere with meiotic recombination and the subsequent progression of meiosis in plants, but few genes involved in meiotic thermotolerance have been characterized. Here, we characterize a maize (Zea mays) classic dominant male-sterile mutant Ms42, which has defects in pairing and synapsis of homologous chromosomes and DNA double-strand break (DSB) repair. Ms42 encodes a member of the heat shock protein family, HSP101, which accumulates in pollen mother cells. Analysis of the dominant Ms42 mutant and hsp101 null mutants reveals that HSP101 functions in RADIATION SENSITIVE 51 loading, DSB repair, and subsequent meiosis. Consistent with these functions, overexpression of Hsp101 in anthers results in robust microspores with enhanced heat tolerance. These results demonstrate that HSP101 mediates thermotolerance during microsporogenesis, shedding light on the genetic basis underlying the adaptation of male meiocytes to high temperatures.

Varicocele associated male infertility: cellular and molecular perspectives of pathophysiology

BACKGROUND

Varicocele is a common risk factor associated with reduced male fertility potential. The current understanding of varicocele pathophysiology does not completely explain the clinical manifestation of infertility. The present treatment options such as antioxidant supplementation and varicocelectomy only helps ∼35% of men to achieve spontaneous pregnancy.

OBJECTIVE

This review aims to summarize the available knowledge on cellular and molecular alterations implicated to varicocele associated male infertility and also highlights the new knowledge generated by 'Omics' technologies.

MATERIALS AND METHODS

PubMed, MEDLINE, Cochrane and Google Scholar databases are searched using different combinations of keywords (varicocele, infertile/fertile men with varicocele, cellular changes, molecular mechanisms, proteome, epigenome, transcriptome and metabolome). A total of 229 relevant human and animal studies published till 2021 were included in this review.

RESULTS

Current understanding advocates oxidative stress (OS) as a major contributory factor to the varicocele associated male infertility. Excessive OS causes alteration in testicular microenvironment and sperm DNA fragmentation which further contributes to infertility. Molecular and omics studies have identified several promising biomarkers such as AAMP, SPINT1, MKI67 (genetic markers), sperm quality and function related protein markers, global sperm DNA methylation level (epigenetic marker), Hspa2, Protamine, Gadd7, Dynlt1 and Beclin1 (mRNA markers), PRDX2, HSPA, APOA2, YKL40 (seminal protein markers), total choline and PHGDH (metabolic markers).

DISCUSSION

Mature spermatozoa harbours a plethora of molecular information in form of proteome, epigenome and transcriptome; which could provide very important clues regarding pathophysiology of varicocele associated infertility. Recent molecular and omics studies in infertile men with varicocele have identified several promising biomarkers. Upon further validation with larger and well-defined studies, some of these biomarkers could aid in varicocele management.

CONCLUSION

The present evidences suggest inclusion of OS and sperm DNA fragmentation tests could be useful to the diagnostic workup for men with varicocele. Furthermore, including precise molecular markers may assist in diagnostics and prognostics of varicocele associated male infertility. This article is protected by copyright. All rights reserved.

ADH5-mediated NO bioactivity maintains metabolic homeostasis in brown adipose tissue

Brown adipose tissue (BAT) thermogenic activity is tightly regulated by cellular redox status, but the underlying molecular mechanisms are incompletely understood. Protein S-nitrosylation, the nitric-oxide-mediated cysteine thiol protein modification, plays important roles in cellular redox regulation. Here we show that diet-induced obesity (DIO) and acute cold exposure elevate BAT protein S-nitrosylation, including UCP1. This thermogenic-induced nitric oxide bioactivity is regulated by S-nitrosoglutathione reductase (GSNOR; alcohol dehydrogenase 5 [ADH5]), a denitrosylase that balances the intracellular nitroso-redox status. Loss of ADH5 in BAT impairs cold-induced UCP1-dependent thermogenesis and worsens obesity-associated metabolic dysfunction. Mechanistically, we demonstrate that Adh5 expression is induced by the transcription factor heat shock factor 1 (HSF1), and administration of an HSF1 activator to BAT of DIO mice increases Adh5 expression and significantly improves UCP1-mediated respiration. Together, these data indicate that ADH5 controls BAT nitroso-redox homeostasis to regulate adipose thermogenesis, which may be therapeutically targeted to improve metabolic health.

Testicular localization of activating transcription factor 1 and its potential function during spermatogenesis

Activating transcription factor 1 (ATF1), belonging to the CREB/ATF family of transcription factors, is highly expressed in the testes. However, its role in spermatogenesis has not yet been established. Here, we aimed to elucidate the impact of ATF1 in spermatogenesis by examining the expression pattern of ATF1 in mice and the effect of ATF1 knockdown in the mouse testes. We found that ATF1 is expressed in various organs, with very high levels in the testes. Immunohistochemical staining showed that ATF1 was localized in the nuclei of spermatogonia and co-localized with proliferating cell nuclear antigen. In ATF1-deficient mice, the seminiferous tubules of the testis contained cells at all developmental stages; however, the number of spermatocytes was decreased. Proliferating cell nuclear antigen expression was decreased and apoptotic cells were rare in the seminiferous tubules. These results indicate that ATF1 plays a role in male germ cell proliferation and sperm production.

Maternal undernutrition during pregnancy and lactation increases transcription factors, ETV5 and GDNF, and alters regulation of apoptosis and heat shock proteins in the testis of adult offspring in the rat

We tested whether changes in Sertoli cell transcription factors and germ cell heat shock proteins (HSPs) are linked to the effects of maternal undernutrition on male offspring fertility. Rats were fed ad libitum with a standard diet (CONTROL) throughout pregnancy and lactation or with 50% of CONTROL intake throughout pregnancy (UNP) or lactation (UNL) or both periods (UNPL). After postnatal Day 21, 10 male pups per group were fed a standard diet ad libitum until postnatal Day 160 when testes were processed for histological, mRNA and immunohistochemical analyses. Compared with CONTROL: caspase-3 was increased in UNP and UNPL (P=0.001); Bax was increased in UNL (P=0.002); Bcl-2 (P<0.0001) was increased in all underfed groups; glial cell line-derived neurotrophic factor (P=0.002) was increased in UNP and UNL; E twenty-six transformation variant gene 5 and HSP70 were increased, and HSP90 was diminished in all underfed groups (P<0.0001). It appears that maternal undernutrition during pregnancy and lactation disrupts the balance between proliferation and apoptosis in germ cells, increasing germ cell production and perhaps exceeding the support capacity of the Sertoli cells. Moreover, fertility could be further compromised by changes in meiosis and spermiogenesis mediated by germ cell HSP90 and HSP70.

Varicocoele and oxidative stress: New perspectives from animal and human studies

BACKGROUND

Varicocoele (VCL), one of the main causes of male subfertility, negatively affects testicular function. Due to limited access to human testicular tissue, animal model studies have been used to evaluate molecular and, recently, epigenetic changes attributed to pathophysiology induced by VCL.

OBJECTIVES

This review aims to provide an update on the latest findings regarding the link between VCL-induced biochemical stress and molecular changes in germ cells and spermatozoa. Endocrine and antioxidant status, testicular chaperone-specific hemostasis failure, altered testicular ion balance, metabolic disorders, and altered carbon cycling during spermatogenesis are among the many features that will be presented.

DISCUSSION

Literature review coupled with our own findings suggests that ionic imbalance, hypoxia, hyperthermia, and altered blood flow could lead to severe chronic oxidative and nitrosative stress in patients with VCL leading to defective spermatogenesis and impairment of the integrity of all sperm cell components and compartments down to the epigenetic information they carry.

CONCLUSION

Since oxidative stress is an important feature of the reproductive pathology of VCL, therapeutic strategies such as the administration of appropriate antioxidants could be undertaken as a complementary non-invasive treatment line.

Case report: A non-obstructive azoospermia patient with heat shock factor-2 mutation

RATIONALE

Infertility is a common medical condition that affects nearly 15% of the world population. Non-obstructive azoospermia (NOA) is one of the most severe forms of male infertility. Some common structural variants, single nucleotide polymorphisms (SNPs), and genetic factors were reported to be associated with NOA. However, the underlying etiology and genetic mechanism(s) remain largely unclear. This report aimed to describe the associated mutation of the heat shock factor-2 (HSF2) gene in Chinese infertile men with NOA.

PATIENT CONCERNS

An apparently healthy 27-year-old man with a body mass index (BMI) of 23.31 kg/m had a 2-year history of primary infertility.

DIAGNOSES

The semen analysis of the patient showed a sperm concentration of 0/mL in 6.5 mL of semen. The patient was diagnosed with NOA by performing the comprehensive examinations including a detailed medical history, physical examination, chromosome analysis, Y-chromosome microdeletions, semen analysis, and hormone profiles.

INTERVENTIONS

The couple received artificial insemination by donor (AID) and a healthy girl was born after the embryo transfer.

OUTCOMES

We found a novel deletion-insertion variation c.326_326delinsGGAAGGTGAGCTATTGT in the exon 3 of the HSF2 gene by performing next-generation sequencing on him who was diagnosed NOA. We performed Sanger sequencing on this patient and confirmed the heterozygous missing insertion mutation in the patient. This is a novel mutation. The variant was heterozygous and categorized as pathogenic.

LESSONS

A novel deletion-insertion variation c.326_326delinsGGAAGGTGAGCTATTGT in the exon 3 of HSF2 gene HSF2 is predicted to be pathogenic and associated with the occurrence of NOA.

Testicular torsion and reperfusion: evidences for biochemical and molecular alterations

This study was done in order to determine the molecular and biochemical alterations following testicular torsion (TT) and torsion-reperfusion (TR). For this purpose, 54 male Wistar rats were divided into five groups as control group (n = 6) and experimental group subjected to 1, 2, 4, and 8 h unilateral left torsion induction (n = 12 in each group). After induction of TT, testicular samples were collected from each group (n = 6), and the other six rats of each group underwent the same period of reperfusion after TT and then were sampled. Histological changes, the mRNA and protein expression of heat shock protein-70 (Hsp70), and caspase-3 were examined using reverse transcriptase-PCR (RT-PCR) and immunohistochemistry, respectively. Testicular total antioxidant capacity (TAC), glutathione peroxidase (GSH-px), and malondialdehyde (MDA) levels were evaluated. The mRNA damage and DNA fragmentation were assessed. The TT and TR significantly reduced differentiation and spermiogenesis indices (p < 0.05). The TT- and TR-induced groups exhibited a severe reduction in Hsp70 expression as well as remarkable enhancement in caspase-3 expression. The TAC and GSH-px levels were decreased and the MDA content was increased in TT- and TR-induced groups. Finally, the TT and TR enhanced mRNA damage and DNA fragmentation. The TT- and TR-induced damaging oxidative stress, diminished Hsp70 expression, and enhanced caspase-3 mRNA and protein levels result in apoptosis following 1, 2, and 4 h. Whereas, following 8 h, TT and TR initiate the necrosis by inducing energy depletion as well as severe mRNA damage.

Human male infertility and its genetic causes

Background

Infertility affects about 15% of couples who wish to have children and half of these cases are associated with male factors. Genetic causes of azoospermia include chromosomal abnormalities, Y chromosome microdeletions, and specific mutations/deletions of several Y chromosome genes. Many researchers have analyzed genes in the AZF region on the Y chromosome; however, in 2003 the SYCP3 gene on chromosome 12 (12q23) was identified as causing azoospermia by meiotic arrest through a point mutation.

Methods

We mainly describe the SYCP3 and PLK4 genes that we have studied in our laboratory, and add comments on other genes associated with human male infertility.

Results

Up to now, The 17 genes causing male infertility by their mutation have been reported in human.

Conclusions

Infertility caused by nonobstructive azoospermia (NOA) is very important in the field of assisted reproductive technology. Even with the aid of chromosomal analysis, ultrasonography of the testis, and detailed endocrinology, only MD‐TESE can confirm the presence of immature spermatozoa in the testes. We strongly hope that these studies help clinics avoid ineffective MD‐TESE procedures.

Transcriptome profiling of the testis reveals genes involved in spermatogenesis and marker discovery in the oriental fruit fly, Bactrocera dorsalis

The testis is a highly specialized tissue that plays a vital role in ensuring fertility by producing spermatozoa, which are transferred to the female during mating. Spermatogenesis is a complex process, resulting in the production of mature sperm, and involves significant structural and biochemical changes in the seminiferous epithelium of the adult testis. The identification of genes involved in spermatogenesis of Bactrocera dorsalis (Hendel) is critical for a better understanding of its reproductive development. In this study, we constructed a cDNA library of testes from male B. dorsalis adults at different ages, and performed de novo transcriptome sequencing to produce a comprehensive transcript data set, using Illumina sequencing technology. The analysis yielded 52 016 732 clean reads, including a total of 4.65 Gb of nucleotides. These reads were assembled into 47 677 contigs (average 443 bp) and then clustered into 30 516 unigenes (average 756 bp). Based on BLAST hits with known proteins in different databases, 20 921 unigenes were annotated with a cut-off E-value of 10(-5). The transcriptome sequences were further annotated using the Clusters of Orthologous Groups, Gene Orthology and the Kyoto Encyclopedia of Genes and Genomes databases. Functional genes involved in spermatogenesis were analysed, including cell cycle proteins, metalloproteins, actin, and ubiquitin and antihyperthermia proteins. Several testis-specific genes were also identified. The transcripts database will help us to understand the molecular mechanisms underlying spermatogenesis in B. dorsalis. Furthermore, 2913 simple sequence repeats and 151 431 single nucleotide polymorphisms were identified, which will be useful for investigating the genetic diversity of B. dorsalis in the future.

Understanding the role of heat shock protein isoforms in male fertility, aging and apoptosis

Heat shock proteins (HSPs) play a role in the homeostasis, apoptosis regulation and the maintenance of the various other physiological processes. Aging is accompanied by a decrease in the resistance to environmental stress, while mitochondria are primary targets in the process of aging, their expression decreasing with age. Mitochondrion also plays a significant role in the process of spermatogenesis. HSPs have been shown to be involved in apoptosis with some of acting as apoptotic inhibitors and are involved in cytoprotection. In this review we discuss the roles of Hsp 27, 60, 70, and 90 in aging and male infertility and have concluded that these particular HSPs can be used as a molecular markers for mitochondrially- mediated apoptosis, aging and male infertility.

Mitochondrial adaptations evoked with exercise are associated with a reduction in age-induced testicular atrophy in Fischer-344 rats

Mitochondrial dysfunction in various tissues has been associated with numerous conditions including aging. In testes, aging induces atrophy and a decline in male reproductive function but the involvement of mitochondria is not clear. The purpose of this study was to examine whether the mitochondrial profile differed with (1) aging, and (2) 10-weeks of treadmill exercise training, in the testes of young (6 month) and old (24 month) Fischer-344 (F344) animals. Old animals exhibited significant atrophy (30 % decline; P < 0.05) in testes compared to young animals. However, relative mitochondrial content was not reduced with age and this was consistent with the lack of change in the mitochondrial biogenesis regulator protein, peroxisome proliferator-activated receptor gamma coactivator 1-alpha and its downstream targets nuclear respiratory factor-1 and mitochondrial transcription factor A. No effect was observed in the pro- or anti-apoptotic proteins, Bax and Bcl-2, respectively, but age increased apoptosis inducing factor levels. Endurance training induced beneficial mitochondrial adaptations that were more prominent in old animals including greater increases in relative mtDNA content, biogenesis/remodeling (mitofusin 2), antioxidant capacity (mitochondrial superoxide dismutase) and lower levels of phosphorylated histone H2AX, an early marker of DNA damage (P < 0.05). Importantly, these exercise-induced changes were associated with an attenuation of testes atrophy in older sedentary animals (P < 0.05). Our results indicate that aging-induced atrophy in testes may not be associated with changes in relative mitochondrial content and key regulatory proteins and that exercise started in late-life elicits beneficial changes in mitochondria that may protect against age-induced testicular atrophy.

Molecular chaperones, cochaperones, and ubiquitination/deubiquitination system: involvement in the production of high quality spermatozoa

Spermatogenesis is a complex process in which mitosis, meiosis, and cell differentiation events coexist. The need to guarantee the production of qualitatively functional spermatozoa has evolved into several control systems that check spermatogenesis progression/sperm maturation and tag aberrant gametes for degradation. In this review, we will focus on the importance of the evolutionarily conserved molecular pathways involving molecular chaperones belonging to the superfamily of heat shock proteins (HSPs), their cochaperones, and ubiquitination/deubiquitination system all over the spermatogenetic process. In this respect, we will discuss the conserved role played by the DNAJ protein Msj-1 (mouse sperm cell-specific DNAJ first homologue) and the deubiquitinating enzyme Ubpy (ubiquitin-specific processing protease-y) during the spermiogenesis in both mammals and nonmammalian vertebrates.

Cloning and expression analysis of a HSP70 gene from Korean rockfish (Sebastes schlegeli)

The gene encoding HSP70 was isolated from Korean rockfish Sebastes schlegeli by homologous cloning and rapid amplification of cDNA ends (RACE). The full-length of HSP70 cDNA was composed of 2259 bp and encoded a polypeptide of 639 amino acids. BLAST analysis showed that HSP70 of S. schlegeli shared high identities with those of the Lates calcarifer, Oreochromis niloticus, Seriola quinqueradiata HSP70s (88-89%). Our current study also revealed that HSP70 of Korean rockfish was expressed in many tissues by RT-PCR under unstressed condition. Quantitative real-time PCR showed that the expression patterns of Korean rockfish HSP70 were developmental stage-dependency. The expression of HSP70 was measured by quantitative real-time PCR after different oxygen treatments. The results showed that expression of HSP70 increased significantly after exposure to hypoxia for 30 min in gill and ovary, and then decreased for 60 min, and the level in spleen and liver gradually increased and reached the highest at 60 min. In addition, in gill, spleen and liver, the HSP70 mRNA level reached the maximum in hypoxia group after one hour different oxygen concentration stress. Increased amounts of serum thyroxine (T4), and triiodothyronine (T3) were also found during 30 min hypoxia treatment and 60 min normoxia group in our study. All of the results provide information to further study the mechanism of physiology and immune function under stress conditions of ovoviviparous teleosts.

Heat stress response of male germ cells

The vast majority of mammalian testes are located outside the body cavity for proper thermoregulation. Heat has an adverse effect on mammalian spermatogenesis and eventually leads to sub- or infertility. Recent studies have provided insights into the molecular response of male germ cells to high temperatures. Here, we review the effects of heat on male germ cells and discuss the mechanisms underlying germ cell loss and impairment. We also discuss the role of translational control in male germ cells as a potential protective mechanism against heat-induced germ cell apoptosis.

Varicocele repair in the era of modern assisted reproductive techniques

PURPOSE OF REVIEW

This review looks at the literature on varicocele repair and its effect on assisted reproductive techniques. The effects of varicocele correction on improved sperm production have been well documented with semen analysis data. What remain to be elucidated are the causes of the varicocele effect and how correction of the resultant pathophysiology may affect the outcomes of modern assisted reproductive technology.

RECENT FINDINGS

Basic science research shows us that varicoceles exert deleterious effects on Leydig cells, Sertoli cells, and germ cells via very different mechanisms. The effects of varicocele correction on the reproductive potential of sperm are less well understood. Clinical research has shown improved semen parameters, DNA integrity, and assisted reproductive technology outcomes after varicocele repair.

SUMMARY

Varicocele correction presents a possible method to optimize a couples' reproductive potential or decrease the need for complex assisted reproductive technology.

A dominant-negative mutation of HSF2 associated with idiopathic azoospermia

Idiopathic azoospermia (IA) is a severe form of male infertility due to unknown causes. The HSF2 gene, encoding the heat shock transcription factor 2, had been suggested to play a significant role in the spermatogenesis process since the Hsf2-knockout male mice showed spermatogenesis defects. To examine whether HSF2 is involved in the pathogenesis of IA in human, we sequenced all the exons of HSF2 in 766 patients diagnosed with IA and 521 proven fertile men. A number of coding mutations private to the patient group, which include three synonymous mutations and five missense mutations, were identified. Of the missense mutations, our functional assay demonstrated that one heterozygous mutation, R502H, caused a complete loss of HSF2 function and that the mutant suppressed the normal function of the wild-type (WT) allele through a dominant-negative effect, thus leading to the dominant penetrance of the mutant allele. These results support a role for HSF2 in the pathogenesis of IA and further implicate this transcription factor as a potential therapeutic target.

Nuclear Ago2/HSP60 contributes to broad spectrum of hATSCs function via Oct4 regulation

AIMS

Argonaute2 (Ago2) plays a fundamental role in microRNA-mediated gene regulation through its intrinsic endonuclease activity. In this study we demonstrate the novel functions and molecular mechanisms by which nuclear Ago2 directly regulates HSP (heat shock protein) 60 expression and stem cell self-renewal. HSP60 is a crucial regulator of ROS (reactive oxygen species), senescence, and apoptotic cell death in several tissues and cell types.

RESULTS

HSP60 is regulated via inactivation of p38/JNK and p53 and binds directly to the regulatory regions of the TERT, c-myc, GPx3, p53, and STAT3 genes. Using HSP60 CHIP-PCR experiments, we show that HSP60 binds directly to the Oct4 and Nanog genes and directly regulates Oct4 and other stemness genes involved in human adipose tissue-derived stem cell (hATSC) differentiation. HSP60 also positively regulates ROS-scavenging factors, including GPx3 and TXNL1, which directly modulate cytosolic ROS in hATSCs. Moreover, our study shows that Oct4 regulates HSP60 expression and controls hATSC survival and self-renewal after binding to the HSP60 gene. Furthermore, HSP60-mediated regulation of Oct4 contributes to neuronal and endodermal β-cell differentiation of hATSCs in vitro and in vivo and downregulates mesoderm-specific gene expression.

INNOVATION AND CONCLUSION

We show that increased levels of Ago2 or HSP60 effectively induce nuclear localization of HSP60, which directly controls Oct4, c-Myc, p53, TERT, and STAT3 for transdifferentiation programs. Collectively, we suggest a novel model in which nuclear Ago2 controls HSP60 in hATSCs.

Roles of heat shock factors in gametogenesis and development

Heat shock factors form a family of transcription factors (four in mammals), which were named according to the first discovery of their activation by heat shock. As a result of the universality and robustness of their response to heat shock, the stress-dependent activation of heat shock factor became a ‘paradigm’: by binding to conserved DNA sequences (heat shock elements), heat shock factors trigger the expression of genes encoding heat shock proteins that function as molecular chaperones, contributing to establish a cytoprotective state to various proteotoxic stress and in several pathological conditions. Besides their roles in the stress response, heat shock factors perform crucial roles during gametogenesis and development in physiological conditions. First, during these process, in stress conditions, they are either proactive for survival or, conversely, for apoptotic process, allowing elimination or, inversely, protection of certain cell populations in a way that prevents the formation of damaged gametes and secure future reproductive success. Second, heat shock factors display subtle interplay in a tissue- and stage-specific manner, in regulating very specific sets of heat shock genes, but also many other genes encoding growth factors or involved in cytoskeletal dynamics. Third, they act not only by their classical transcription factor activities, but are necessary for the establishment of chromatin structure and, likely, genome stability. Finally, in contrast to the heat shock gene paradigm, heat shock elements bound by heat shock factors in developmental process turn out to be extremely dispersed in the genome, which is susceptible to lead to the future definition of ‘developmental heat shock element’.

Glucose-regulated protein precursor (GRP78) and tumor rejection antigen (GP96) are unique to hamster caput epididymal spermatozoa

The immotile testicular mammalian spermatozoon gets transformed into a motile spermatozoon during 'epididymal maturation'. During this process, the spermatozoa transit from the caput to the cauda epididymis and undergo a number of distinct morphological, biophysical and biochemical changes, including changes in protein composition and protein modifications, which may be relevant to the acquisition of motility potential. The present proteome-based study of the hamster epididymal spermatozoa of caput and cauda led to the identification of 113 proteins spots using Matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS) analysis. Comparison of these 113 protein spots indicated that 30 protein spots (corresponding to 20 proteins) were significantly changed in intensity. Five proteins were increased and eleven were decreased in intensity in the cauda epididymal spermatozoa. In addition, two proteins, glucose-regulated protein precursor (GRP78) and tumor rejection antigen (GP96), were unique to the caput epididymal spermatozoa, while one protein, fibrinogen-like protein 1, was unique to cauda epididymal spermatozoa. A few of the five proteins, which increased in intensity, were related to sperm metabolism and ATP production during epididymal maturation. The changes in intensity of a few proteins such as ERp57, GRP78, GP96, Hsp60, Hsp70, and dihydrolipoamide S-acetyltransferase were validated by immunoblotting. The present study provides a global picture of the changes in protein composition occurring during hamster sperm epididymal maturation, besides being the first ever report on the proteome of hamster spermatozoa.

Molecular cloning and bioinformatic analysis of SPATA4 gene

Full-length cDNA sequences of four novel SPATA4 genes in chimpanzee, cow, chicken and ascidian were identified by bioinformatic analysis using mouse or human SPATA4 cDNA fragment as electronic probe. All these genes have 6 exons and have similar protein molecular weight and do not localize in sex chromosome. The mouse SPATA4 sequence is identified as significantly changed in cryptorchidism, which shares no significant homology with any known protein in swissprot databases except for the homologous genes in various vertebrates. Our searching results showed that all SPATA4 proteins have a putative conserved domain DUF1042. The percentages of putative SPATA4 protein sequence identity ranging from 30 % to 99 %. The high similarity was also found in 1 kb promoter regions of human, mouse and rat SPATA4 gene. The similarities of the sequences upstream of SPATA4 promoter also have a high proportion. The results of searching SymAtlas (http://symatlas.gnf.org/SymAtlas/) showed that human SPATA4 has a high expression in testis, especially in testis interstitial, leydig cell, seminiferous tubule and germ cell. Mouse SPATA4 was observed exclusively in adult mouse testis and almost no signal was detected in other tissues. The pI values of the protein are negative, ranging from 9.44 to 10.15. The subcellular location of the protein is usually in the nucleus. And the signal peptide possibilities for SPATA4 are always zero. Using the SNPs data in NCBI, we found 33 SNPs in human SPATA4 gene genomic DNA region, with the distribution of 29 SNPs in the introns. CpG island searching gives the data about CpG island, which shows that the regions of the CpG island have a high similarity with each other, though the length of the CpG island is different from each other. This research is a fundamental work in the fields of the bioinformational analysis, and also put forward a new way for the bioinformatic analysis of other genes.

Hsp70 is required for optimal cell proliferation in mouse A6 mesoangioblast stem cells

Mouse Hsp70 (70 kDa heat shock protein) is preferentially induced by heat or stress stimuli. We previously found that Hsp70 is constitutively expressed in A6 mouse mesoangioblast stem cells, but its possible role in these cells and the control of its basal transcription remained unexplored. Here we report that in the absence of stress, Ku factor is able to bind the HSE (heat shock element) consensus sequence in vitro, and in vivo it is bound to the proximal hsp70 promoter. In addition, we show that constitutive hsp70 transcription depends on the co-operative interaction of different factors such as Sp1 (specificity protein 1) and GAGA-binding protein with Ku factor, which binds the HSE consensus sequence. We used mRNA interference assays to select knockdown cell clones. These cells were able to respond to heat stress by producing a large amount of Hsp70, and produced the same amount of Hsp70 as that synthesized by stressed A6 cells. However, severe Hsp70 knockdown cells had a longer duplication time, suggesting that constitutive Hsp70 expression has an effect on the rate of proliferation.

Structural characterization of the medfly hsp83 gene and functional analysis of its proximal promoter region in vivo by germ-line transformation

In order to define the regulatory elements responsible for the expression of the medfly hsp83 (Cchsp83) gene, we determined the sequence of a genomic region of the gene that included 3,536 bp upstream of the transcription initiation site, the first untranslated exon of 144 bp, a 275-bp intron, and 516 bp of the second coding exon. Structural analysis of the 5' flanking region revealed the presence of a typical TATA box, 28 bp upstream of the transcription start site, and seven putative heat shock elements (HSEs) further upstream. The 5' untranslated region of the Cchsp83 mRNA was found to contain extensive secondary structure in the first 126 nucleotides. We carried out deletion functional analysis of the proximal promoter region (-380/+139) in vivo by germ line transformation using the lacZ as a reporter gene. We found that sequences in the -380/-86 region are essential for the constitutive expression of the Cchsp83 gene. Under normal conditions, the -380/+139 region was able to drive significant levels of transgene expression in all developmental stages of the medfly as well as in the ovaries and testis. In most stages, the temporal expression pattern of the reporter gene was similar to the respective pattern of the endogenous Cchsp83 gene. Although the -380/+139 promoter region contained two putative HSEs, it was found unable to confer any heat-induced expression in the reporter gene.

Proteomic investigation of 1,6-dimethoxyhexane testicular toxicity

The aliphatic ether 1,6-dimethoxyhexane (DMH) was previously identified as a testicular toxicant. Testis protein extracts from control and DMH-treated rats were subjected to two-dimensional gel electrophoresis for comparison of protein expression profiles. MALDI-ToF peptide mass fingerprinting of differentially expressed proteins resulted in the conclusive identification of heat shock-related 70kDa protein 2 (HSP70.2), 60kDa heat shock protein, mitochondrial precursor (HSP60) and protein disulfide isomerase A3 precursor (ERp60). The potential involvement of these proteins in chemically induced perturbation of spermatogenesis and their utility as biomarkers of testicular toxicity are discussed in light of the knowledge currently available from the literature.

Cloning and characterization of chicken SPATA4 gene and analysis of its specific expression

The spermatogenesis associated 4 gene (SPATA4, previously named TSARG2) was first cloned from a mouse testis cDNA library and was reported to be a candidate apoptosis-related gene in male germ cells. In this study, we cloned and characterized the SPATA4 gene from chicken (Gallus gallus). Bioinformatics analysis shows that the chicken SPATA4 gene is located on chromosome 4, is made up of six exons, and contains an 860 bp open reading frame encoding a putative protein of 250 amino acids. Further analysis of the SPATA4 gene sequence indicates that it is highly conserved between avian and mammalian species. Multi-tissue RT-PCR results indicate that the chicken SPATA4 gene is specifically expressed in the testis. Moreover, according to multi-time RT-PCR results, the expression of chicken SPATA4 occurs in a development stage-dependent pattern, and is gradually upregulated during the developmental process in chicken testis. All of these results suggest that SPATA4 may play an important role in the chicken spermatogenesis process.

Heat shock transcription factor 1 down-regulates spermatocyte-specific 70 kDa heat shock protein expression prior to the induction of apoptosis in mouse testes

Expression of constitutively active heat shock transcription factor 1 (HSF1) in mouse spermatocytes induces apoptosis and leads to male infertility. We report here that prior to the onset of massive apoptosis caused by expression of active HSF1 in spermatocytes a marked reduction in spermatocyte-specific Hsp70.2 mRNA and protein levels occurs. In addition, HSP70.2 protein relocalizes from a predominant cytoplasmic to a nuclear position in developing spermatocytes that express active HSF1. Later in the developmental stages, cells undergoing HSF1-induced apoptosis essentially lack the HSP70.2 protein. The down-regulation of Hsp70.2 gene expression by HSF1 is paradoxical because HSF1 is the prototypical activator of HSP genes. Furthermore, HSF1-mediated repression neither involved a heat shock element (HSE)-like sequence adjacent to the Hsp70.2 gene nor were Hsp70.2 promoter sequences associated directly with HSF1. Interestingly, other spermatocyte- and spermatid-specific transcripts are also down-regulated in testes of transgenic mice expressing active HSF1, suggesting involvement of a putative HSF1-dependent block of development of spermatogenic cells. Importantly however, transcription of the Hsp70.2 gene is down-regulated in testes of wild-type mice subjected to a hyperthermia that induces transient activation of HSF1, indicating that the spermatocyte-specific activity of HSF1 might misdirect a network of transcription factors required for proper regulation of Hsp70.2.

Apoptosis versus cell differentiation: role of heat shock proteins HSP90, HSP70 and HSP27

Heat shock proteins HSP27, HSP70 and HSP90 are molecular chaperones whose expression is increased after many different types of stress. They have a protective function helping the cell to cope with lethal conditions. The cytoprotective function of HSPs is largely explained by their anti-apoptotic function. HSPs have been shown to interact with different key apoptotic proteins. As a result, HSPs can block essentially all apoptotic pathways, most of them involving the activation of cystein proteases called caspases. Apoptosis and differentiation are physiological processes that share many common features, for instance, chromatin condensation and the activation of caspases are frequently observed. It is, therefore, not surprising that many recent reports imply HSPs in the differentiation process. This review will comment on the role of HSP90, HSP70 and HSP27 in apoptosis and cell differentiation. HSPs may determine de fate of the cells by orchestrating the decision of apoptosis versus differentiation.

Altered expression pattern of heat shock transcription factor, Y chromosome (HSFY) may be related to altered differentiation of spermatogenic cells in testes with deteriorated spermatogenesis

OBJECTIVE

To evaluate the expression patterns of heat shock transcription factor, Y chromosome (HSFY), in the testes showing deteriorated spermatogenesis.

DESIGN

Prospective study.

SETTING

University hospital, its branch hospital, and academic laboratory.

PATIENT(S)

Men undergoing testicular biopsy for the investigation of infertility and men undergoing orchiectomy for testicular cancer.

INTERVENTION(S)

After pathologic evaluation, specimens were subdivided into three groups: normal spermatogenesis (n = 8), maturation arrest (n = 5), and Sertoli cell-only syndrome (n = 4). Immunostaining and Western blotting techniques determined the expression of HSFY.

MAIN OUTCOME MEASURE(S)

Expression of HSFY in testes.

RESULT(S)

Western blotting data revealed HSFY in the testicular tissues with normal spermatogenesis, maturation arrest, and Sertoli cell-only syndrome, but the amount of the protein in the maturation arrest and Sertoli cell-only syndrome samples was altered. The immunohistochemical data demonstrated that HSFY was expressed in spermatogenic cells and Sertoli cells in all specimens. However, the expression of HSFY was low or absent in spermatogenic cells of maturation arrest specimens, and the ratio of HSFY expressed in Sertoli cells was different in the specimens with maturation arrest and with Sertoli cell-only syndrome.

CONCLUSION(S)

Altered expression of the HSFY in the testis showing deteriorated spermatogenesis may be associated with alteration of spermatogenic cell differentiation.

Molecular cloning of a novel rat gene Tsarg1, a member of the DnaJ/HSP40 protein family

Beginning with a mouse gene mTSARG3, which was related to apoptosis of spermatogenic cells, bioinformatics was applied and a predicted novel rat gene full-length cDNA sequence was attained. Gene-specific primers were designed for PCR in rat testis cDNA library. A new gene Tsarg1 (GenBank Accession No. AY380804) was cloned, which is related to apoptosis in rat spermatogenic cells. The gene whose full cDNA length is 1176 bp containing 8 exons and 7 introns is located in rat chromosome 1q32-1q33, which encoded a protein containing 316 amino acid residues and being a new member of HSP40 protein family since the sequence contains the highly conserved J domain, which is present in all DnaJ-like proteins and is supported to have a critical role in DnaJ-DnaK protein-protein interactions. The results of RT-PCR and Northern blot analysis showed that Tsarg1 was specifically expressed in rat testis, which probably inhibits rat testis spermatogenic cell apoptosis.

Role of HSPs and telomerase in radiotherapy

The inability of radiotherapy to control tumour growth is still a daunting clinical problem leading to failure of the overall treatment regimens. The fundamental question is; could tumour cells be specifically sensitized to ionizing radiation (IR) by heat or factors exclusively expressed in tumour cells? One such factor, expressed in most tumours and silent in somatic cells, is telomerase. Biochemical and genetic studies have established an association between telomere maintenance and extended life span of human cells mediated through the expression of the catalytic sub-unit of telomerase (hTERT). Because of this, telomerase is an attractive target for inhibition in anti-cancer therapy. Telomeres are maintained by telomerase and hTERT interacts with heat shock protein (HSP) chaperones. This review will focus on the possible role of HSPs and telomerase in sensitizing tumour cells and, thus, enhancing the potential of targeted radiotherapy.

A reference map and identification of porcine testis proteins using 2-DE and MS

The development of the testis is essential for maturation of male mammals. A complete understanding of proteins expressed in the testis will provide biological information on many reproductive dysfunctions in males. The purposes of this study were to apply a proteomic approach to investigating protein composition and to establish a 2-D PAGE reference map for porcine testis proteins. MALDI-TOF MS was performed for protein identification. When 1 mg of total proteins was assayed by 2-D PAGE and stained with colloidal CBB, more than 400 proteins with a pI of pH 3-10 and M(r) of 10-200 kDa could be detected. Protein expression varied among individuals, with CV between 4.7 and 131.5%. A total of 447 protein spots were excised for identification, among which 337 spots were identified by searching the mass spectra against the NCBInr database. Identification of the remaining 110 spots was unsuccessful. A 2-D PAGE-based porcine testis protein database has been constructed on the basis of the results and will be published on the WWW. This database should be valuable for investigating the developmental biology and pathology of porcine testis.

TCP10L is expressed specifically in spermatogenic cells and binds to death associated protein kinase-3

The human transcriptional factor T-complex protein 10 like (TCP10L) gene is expressed exclusively in the liver and testis. However, the function of TCP10L in the testis remains unknown. We examined the expression of TCP10L in human testis and found that TCP10L was expressed specifically in the nucleus of spermatogenic cells during spermatogenesis. In addition, we identified death associated protein kinase 3 (DAPK-3/ZIP kinase) as a binding partner for TCP10L by yeast two-hybrid screening, followed with immunoprecipitation and subcellular localization experiments. Mutagenesis study revealed that this interaction was dependant on the leucine zipper motif-containing region. The specific expression pattern of TCP10L and interaction with DAPK-3 implies that TCP10L might play crucially important roles in spermatogenesis through its interaction with DAPK-3.

Heat-shock protein 60 is required for blastema formation and maintenance during regeneration

Zebrafish fin regeneration requires the formation and maintenance of blastema cells. Blastema cells are not derived from stem cells but behave as such, because they are slow-cycling and are thought to provide rapidly proliferating daughter cells that drive regenerative outgrowth. The molecular basis of blastema formation is not understood. Here, we show that heat-shock protein 60 (hsp60) is required for blastema formation and maintenance. We used a chemical mutagenesis screen to identify no blastema (nbl), a zebrafish mutant with an early fin regeneration defect. Fin regeneration failed in nbl due to defective blastema formation. nbl also failed to regenerate hearts. Positional cloning and mutational analyses revealed that nbl results from a V324E missense mutation in hsp60. This mutation reduced hsp60 function in binding and refolding denatured proteins. hsp60 expression is increased during formation of blastema cells, and dysfunction leads to mitochondrial defects and apoptosis in these cells. These data indicate that hsp60 is required for the formation and maintenance of regenerating tissue.

Developmental changes of heat-shock proteins in porcine testis by a proteomic analysis

Heat-shock proteins (HSPs) are important in spermatogenesis. This study investigated developmental changes in the expression of major HSPs in porcine testis. The testis from five immature (mean age 2.9+/-0.1 months) and five mature boars (35.7+/-14.0 months) were examined. Two-dimensional polyacrylamide gel electrophoresis was conducted and proteins were identified by Western blotting and/or matrix-assisted laser desorption/ionization mass spectrometry. Moreover, the 90, 70, and 60 kDa HSPs, 70 kDa heat-shock cognate protein (HSC 70), tubulin, and actin were quantified on two-dimensional gels. Protein spots were quantified by densitometry, combined with a computer-assisted image analysis system. Immunohistochemistry was performed to analyze the expression pattern of major HSPs and beta-tubulin in testis. One isoform of HSP 90 (HSP 90 alpha), two isoforms of HSC 70 (HSC 70a and HSC 70c), one isoform of HSP70 (HSP 70e), and tubulin increased after sexual maturation (P<0.05). A testis-specific HSP70 (P70t) was markedly increased in the testes of sexually mature boars. Meanwhile, levels of actin and some isoforms of HSPs including 60 kDa HSP remained similar in both groups. These observations were further confirmed by immunohistochemistry; therefore, the upregulation of protein expression in the adult testis could be attributed to a higher level of protein expression and the number of cells that were HSPs-positive already resided in the immature testis. The differential expression of major HSPs suggested that they may be important in porcine spermatogenesis.