HSP70-2 is required for CDC2 kinase activity in meiosis I of mouse spermatocytes

The potential value of cancer-testis antigens in ovarian cancer: Prognostic markers and targets for immunotherapy

BACKGROUND

Tumor immunotherapy has become an important adjuvant therapy after surgery, radiotherapy, and chemotherapy. In recent years, the role of tumor-associated antigen (TAA) in tumor immunotherapy has become increasingly prominent. Cancer-testis antigen (CTA) is a kind of TAA that is highly restricted in a variety of tumors and can induce an immune response.

AIMS

This review article aimed to evaluate the role of CTA on the progression of ovarian cancer, its diagnostic efficacy, and the potential for immunotherapy.

METHODS

We analyzed publications and outlined a comprehensive of overview the regulatory mechanism, immunogenicity, clinical expression significance, tumorigenesis, and application prospects of CTA in ovarian cancer, with a particular focus on recent progress in CTA-based immunotherapy.

RESULTS

The expression of CTA affects the occurrence, development, and prognosis of ovarian cancer and is closely related to tumor immunity.

CONCLUSION

CTA can be used as a biomarker for the diagnosis and prognosis evaluation of ovarian cancer and is an ideal target for antitumor immunotherapy. These findings provide novel insights on CTA in the improvement of diagnosis and treatment for ovarian cancer. The successes, current challenges and future prospects were also discussed to portray its significant potential.

ZFP541 and KCTD19 regulate chromatin organization and transcription programs for male meiotic progression

The successful progression of meiosis prophase I requires integrating information from the structural and molecular levels. In this study, we show that ZFP541 and KCTD19 work in the same genetic pathway to regulate the progression of male meiosis and thus fertility. The Zfp541 and/or Kctd19 knockout male mice show various structural and recombination defects including detached chromosome ends, aberrant localization of chromosome axis components and recombination proteins, and globally altered histone modifications. Further analyses on RNA-seq, ChIP-seq, and ATAC-seq data provide molecular evidence for the above defects and reveal that ZFP541/KCTD19 activates the expression of many genes by repressing several major transcription repressors. More importantly, we reveal an unexpected role of ZFP541/KCTD19 in directly modulating chromatin organization. These results suggest that ZFP541/KCTD19 simultaneously regulates the transcription cascade and chromatin organization to ensure the coordinated progression of multiple events at chromosome structural and biochemical levels during meiosis prophase I.

Regulation of germline proteostasis by HSF1 and insulin/IGF-1 signaling

Protein homeostasis (proteostasis) is essential for cellular function and organismal health and requires the concerted actions of protein synthesis, folding, transport, and turnover. In sexually reproducing organisms, the immortal germline lineage passes genetic information across generations. Accumulating evidence indicates the importance of proteome integrity for germ cells as genome stability. As gametogenesis involves very active protein synthesis and is highly energy-demanding, it has unique requirements for proteostasis regulation and is sensitive to stress and nutrient availability. The heat shock factor 1 (HSF1), a key transcriptional regulator of cellular response to cytosolic and nuclear protein misfolding has evolutionarily conserved roles in germline development. Similarly, insulin/insulin-like growth factor-1 (IGF-1) signaling, a major nutrient-sensing pathway, impacts many aspects of gametogenesis. Here, we focus on HSF1 and IIS to review insights into their roles in germline proteostasis and discuss the implications on gamete quality control during stress and aging.

Novel NLRP14 Mutations Induce Azoospermia

Background. LR family pyrin domain-containing 14 (NLRP14 or NALP14) is one of the important members of the NLR family and was mainly expressed in testis. It is reported that deficiency in the NALP14 gene in mice can cause spermatogenic failure, and several NALP14 mutations have been found in oligospermia and infertile men. Case Presentation. This study reported two novel NALP14 mutations (c.2076delC: p.L697X and c.T2963C: p.F988S) in our patients with azoospermia. The exonic deletion mutation (c.2076delC) and one missense mutation (c.T2963C) were firstly screened out by whole-exome sequencing (WES) and further verified by amplifying and sequencing the specific exons 5 and 10. Histological analysis of testicular biopsy revealed that NALP14 expression was detected strongly in spermatogonia and weakly in early spermatocytes. Additionally, mutations in this gene caused meiotic arrest, and no postmeiotic round spermatids and mature spermatozoa were observed in the seminiferous tubules. Conclusions. This study and previous literatures showed that NLRP14 mutations are closely related to male infertility; we discovered two novel NALP14 mutations and summarized the kinds of literatures on NLRP14 mutations and male infertility. This is the first report that deletion mutation (c.2076delC) and one missense mutation (c.T2963C) in NALP14 all lead to azoospermia, which is still significant to the clinical auxiliary diagnosis of male infertility.

CLPP Depletion Causes Diplotene Arrest; Underlying Testis Mitochondrial Dysfunction Occurs with Accumulation of Perrault Proteins ERAL1, PEO1, and HARS2

Human Perrault syndrome (PRLTS) is autosomal, recessively inherited, and characterized by ovarian insufficiency with hearing loss. Among the genetic causes are mutations of matrix peptidase CLPP, which trigger additional azoospermia. Here, we analyzed the impact of CLPP deficiency on male mouse meiosis stages. Histology, immunocytology, different OMICS and biochemical approaches, and RT-qPCR were employed in CLPP-null mouse testis. Meiotic chromosome pairing and synapsis proceeded normally. However, the foci number of the crossover marker MLH1 was slightly reduced, and foci persisted in diplotene, most likely due to premature desynapsis, associated with an accumulation of the DNA damage marker γH2AX. No meiotic M-phase cells were detected. Proteome profiles identified strong deficits of proteins involved in male meiotic prophase (HSPA2, SHCBP1L, DMRT7, and HSF5), versus an accumulation of AURKAIP1. Histone H3 cleavage, mtDNA extrusion, and cGAMP increase suggested innate immunity activation. However, the deletion of downstream STING/IFNAR failed to alleviate pathology. As markers of underlying mitochondrial pathology, we observed an accumulation of PRLTS proteins ERAL1, PEO1, and HARS2. We propose that the loss of CLPP leads to the extrusion of mitochondrial nucleotide-binding proteins to cytosol and nucleus, affecting late meiotic prophase progression, and causing cell death prior to M-phase entry. This phenotype is more severe than in mito-mice or mutator-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.

Loss, Gain, and Retention: Mechanisms Driving Late Prophase I Chromosome Remodeling for Accurate Meiotic Chromosome Segregation

To generate gametes, sexually reproducing organisms need to achieve a reduction in ploidy, via meiosis. Several mechanisms are set in place to ensure proper reductional chromosome segregation at the first meiotic division (MI), including chromosome remodeling during late prophase I. Chromosome remodeling after crossover formation involves changes in chromosome condensation and restructuring, resulting in a compact bivalent, with sister kinetochores oriented to opposite poles, whose structure is crucial for localized loss of cohesion and accurate chromosome segregation. Here, we review the general processes involved in late prophase I chromosome remodeling, their regulation, and the strategies devised by different organisms to produce bivalents with configurations that promote accurate segregation.

C2CD6 regulates targeting and organization of the CatSper calcium channel complex in sperm flagella

The CatSper cation channel is essential for sperm capacitation and male fertility. The multi-subunit CatSper complexes form highly organized calcium signaling nanodomains on flagellar membranes. Here, we report identification of an uncharacterized protein, C2CD6, as a subunit of the mouse CatSper complex. C2CD6 contains a calcium-dependent, membrane-targeting C2 domain. C2CD6 associates with the CatSper calcium-selective, core-forming subunits. Deficiency of C2CD6 depletes the CatSper nanodomains from the flagellum and results in male sterility. C2CD6-deficient sperm are defective in hyperactivation and fail to fertilize oocytes both in vitro and in vivo. CatSper currents are present but at a significantly lower level in C2CD6-deficient sperm. Transient treatments with either Ca2+ ionophore, starvation, or a combination of both restore the fertilization capacity of C2CD6-deficient sperm. C2CD6 interacts with EFCAB9, a pH-dependent calcium sensor in the CatSper complex. We postulate that C2CD6 facilitates incorporation of the CatSper complex into the flagellar plasma membrane and may function as a calcium sensor. The identification of C2CD6 may enable the long-sought reconstitution of the CatSper ion channel complex in a heterologous system for male contraceptive development.

Heat Shock Factors in Protein Quality Control and Spermatogenesis

Proper regulation of cellular protein quality control is crucial for cellular health. It appears that the protein quality control machinery is subjected to distinct regulation in different cellular contexts such as in somatic cells and in germ cells. Heat shock factors (HSFs) play critical role in the control of quality of cellular proteins through controlling expression of many genes encoding different proteins including those for inducible protein chaperones. Mammalian cells exert distinct mechanism of cellular functions through maintenance of tissue-specific HSFs. Here, we have discussed different HSFs and their functions including those during spermatogenesis. We have also discussed the different heat shock proteins induced by the HSFs and their activities in those contexts. We have also identified several small molecule activators and inhibitors of HSFs from different sources reported so far.

Evaluation of seminal plasma HSPA2 protein as a biomarker of human spermatogenesis status

In mammals, testicular Heat shock-related 70 kDa protein 2 (HSPA2) is a chaperon strictly linked to spermatogenesis status, whereas its presence in spermatozoa ensures successful oocyte fertilization. However, there is little information on this protein in seminal plasma in infertile males. Based on our previous two independent studies, we have selected HSPA2 to evaluate this seminal plasma protein is a potential biomarker of correct spermatogenesis. Using immunoblotting and mass spectrometry (MS) we have screened human seminal plasma samples for the presence of HSPA2. Samples were obtained from individuals with normozoospermia, cryptozoospermia, non-obstructive and obstructive azoospermia. Our results showed a lack of HSPA2 in seminal plasma in all azoospermic males however, in cryptozoospermia the results were extremely diversified. Additionally, the application of 2-dimensional gel electrophoresis (2-DE) indicated the presence of additional protein isoforms suggesting possible mechanisms underlying the male infertility. Our findings suggest seminal plasma HSPA2 protein as a possible biomarker not only of spermatogenesis status, especially in cryptozoospermic males, but also as a biomarker predicting the success of reproductive treatment including assisted reproductive techniques (ART).

Role of Heat Shock Proteins (HSP70 and HSP90) in Viral Infection

Heat shock proteins (HSPs) are a large group of chaperones found in most eukaryotes and bacteria. They are responsible for the correct protein folding, protection of the cell against stressors, presenting immune and inflammatory cytokines; furthermore, they are important factors in regulating cell differentiation, survival and death. Although the biological function of HSPs is to maintain cell homeostasis, some of them can be used by viruses both to fold their proteins and increase the chances of survival in unfavorable host conditions. Folding viral proteins as well as replicating many different viruses are carried out by, among others, proteins from the HSP70 and HSP90 families. In some cases, the HSP70 family proteins directly interact with viral polymerase to enhance viral replication or they can facilitate the formation of a viral replication complex and/or maintain the stability of complex proteins. It is known that HSP90 is important for the expression of viral genes at both the transcriptional and the translational levels. Both of these HSPs can form a complex with HSP90 and, consequently, facilitate the entry of the virus into the cell. Current studies have shown the biological significance of HSPs in the course of infection SARS-CoV-2. A comprehensive understanding of chaperone use during viral infection will provide new insight into viral replication mechanisms and therapeutic potential. The aim of this study is to describe the molecular basis of HSP70 and HSP90 participation in some viral infections and the potential use of these proteins in antiviral therapy.

Polyubiquitin gene Ubb is required for upregulation of Piwi protein level during mouse testis development

Testis development, including early embryonic gonad formation and late postnatal spermatogenesis, is essential for the reproduction of higher metazoans to generate fertile gametes, called sperm. We have previously reported that the polyubiquitin gene Ubb is required for fertility in both male and female mice. In particular, the Ubb-null male mice showed an azoospermia phenotype due to arrest of spermatogenesis at the pachytene stage. Here, we analyzed the whole testis proteome at postnatal day 20 to define the molecular mediators of the male-infertility phenotype caused by Ubb knockout. From the identified proteome, 564 proteins were significantly and differentially expressed in Ubb-knockout testes and, among these, 36 downregulated proteins were involved at different stages of spermatogenesis. We also found that levels of piRNA metabolic process-related proteins, including Piwil2 and Tdrd1, were downregulated in Ubb-null testes through functional gene ontology analysis. Further, protein-protein interaction mapping revealed that 24 testis development-related proteins, including Hsp90aa1, Eef1a1, and Pabpc1, were directly influenced by the depletion of ubiquitin. In addition, the reduced mRNA levels of these proteins were observed in Ubb-knockout testes, which closely resembled the global downregulation of piRNA-metabolic gene expression at the transcriptional and post-transcriptional levels. Together with proteomic and transcriptional analyses, our data suggest that Ubb expression is essential for the maintenance of testicular RNA-binding regulators and piRNA-metabolic proteins to complete spermatogenesis in mice.

Regulation of Meiotic Prophase One in Mammalian Oocytes

In female mammals, meiotic prophase one begins during fetal development. Oocytes transition through the prophase one substages consisting of leptotene, zygotene, and pachytene, and are finally arrested at the diplotene substage, for months in mice and years in humans. After puberty, luteinizing hormone induces ovulation and meiotic resumption in a cohort of oocytes, driving the progression from meiotic prophase one to metaphase two. If fertilization occurs, the oocyte completes meiosis two followed by fusion with the sperm nucleus and preparation for zygotic divisions; otherwise, it is passed into the uterus and degenerates. Specifically in the mouse, oocytes enter meiosis at 13.5 days post coitum. As meiotic prophase one proceeds, chromosomes find their homologous partner, synapse, exchange genetic material between homologs and then begin to separate, remaining connected at recombination sites. At postnatal day 5, most of the oocytes have reached the late diplotene (or dictyate) substage of prophase one where they remain arrested until ovulation. This review focuses on events and mechanisms controlling the progression through meiotic prophase one, which include recombination, synapsis and control by signaling pathways. These events are prerequisites for proper chromosome segregation in meiotic divisions; and if they go awry, chromosomes mis-segregate resulting in aneuploidy. Therefore, elucidating the mechanisms regulating meiotic progression is important to provide a foundation for developing improved treatments of female infertility.

Proteostasis in the Male and Female Germline: A New Outlook on the Maintenance of Reproductive Health

For fully differentiated, long lived cells the maintenance of protein homeostasis (proteostasis) becomes a crucial determinant of cellular function and viability. Neurons are the most well-known example of this phenomenon where the majority of these cells must survive the entire course of life. However, male and female germ cells are also uniquely dependent on the maintenance of proteostasis to achieve successful fertilization. Oocytes, also long-lived cells, are subjected to prolonged periods of arrest and are largely reliant on the translation of stored mRNAs, accumulated during the growth period, to support meiotic maturation and subsequent embryogenesis. Conversely, sperm cells, while relatively ephemeral, are completely reliant on proteostasis due to the absence of both transcription and translation. Despite these remarkable, cell-specific features there has been little focus on understanding protein homeostasis in reproductive cells and how/whether proteostasis is "reset" during embryogenesis. Here, we seek to capture the momentum of this growing field by highlighting novel findings regarding germline proteostasis and how this knowledge can be used to promote reproductive health. In this review we capture proteostasis in the context of both somatic cell and germline aging and discuss the influence of oxidative stress on protein function. In particular, we highlight the contributions of proteostasis changes to oocyte aging and encourage a focus in this area that may complement the extensive analyses of DNA damage and aneuploidy that have long occupied the oocyte aging field. Moreover, we discuss the influence of common non-enzymatic protein modifications on the stability of proteins in the male germline, how these changes affect sperm function, and how they may be prevented to preserve fertility. Through this review we aim to bring to light a new trajectory for our field and highlight the potential to harness the germ cell's natural proteostasis mechanisms to improve reproductive health. This manuscript will be of interest to those in the fields of proteostasis, aging, male and female gamete reproductive biology, embryogenesis, and life course health.

Association of heat shock protein A2 expression and sperm quality after N-acetyl-cysteine supplementation in astheno-terato-zoospermic infertile men

In infertile men, reduced expression of heat shock protein A2 (HSPA2) is related to reduced sperm quality and function. The present study has aimed to investigate the effects of N-acetyl-cysteine (NAC) supplementation on expression of heat shock protein A2 (HSPA2). In this study in continuation of previous study, semen samples from 50 astheno-terato-zoospermic men who have received NAC (600 mg/day) orally for three months were evaluated for expression HSPA2 using RT-PCR, and Western blot analysis. In addition, semen samples of these individuals were assessed for sperm parameters, DNA fragmentation (TUNEL), protamine deficiency (CMA3), lipid peroxidation index (MDA) and total antioxidant capacity (TCA). All assessment was carried out before and after NAC treatment. In addition to improved sperm parameters and aforementioned functional parameters, the presented results revealed the significant increase in relative expression levels of HSPA2 was obtained after using NAC treatment (p < .05). Correlation analysis also demonstrated that HSPA2 expression is significantly related to most of the assessed parameters. NAC may directly or indecently impose its beneficial effect through increased expression of HSPA2, which plays a potential role in proper folding of element needed to counteract stress condition in infertile individuals.

Novel targets identified by integrated proteomic and phosphoproteomic analysis in spermatogenesis of swamp buffalo (Bubalus bubalis)

To understand mechanisms of spermatogenesis, the proteome and the phosphoproteome in prepubertal and pubertal swamp buffalo (Bubalus bubalis) testes were analyzed using tandem mass tag (TMT) coupled with liquid chromatography-tandem mass spectrometry (LC–MS/MS). In prepubertal testes, 80 proteins were overexpressed, 148 proteins were underexpressed, and 139 and 142 protein sites had higher and lower phosphorylation, respectively, compared to the levels in pubertal testes. Several of these proteins were associated with reproductive processes such as sexual reproduction, spermatogenesis, fertilization, and spermatid development. In particular, outer dense fiber protein 1 (ODF1), protein maelstrom homolog (MAEL), actin-like protein 7B (ACTL7B), tyrosine-(Y)-phosphorylation regulated (CABYR), and tripartite motif containing 36 (TRIM36) were upregulated with age at both the proteome and phosphoproteome levels. Combining proteome and phosphoproteome analysis can be effectively applied to study the protein/phosphorylation patterns of buffalo testes. These data provide new regulatory candidates and evidence for a complex network in spermatogenesis in buffalo testes, and serve as an important resource for exploring the physiological mechanism of spermatogenesis in mammals.

A noncanonical role of NOD-like receptor NLRP14 in PGCLC differentiation and spermatogenesis

NOD-like receptors (NLRs) are traditionally recognized as key surveillance pattern recognition receptors (PRRs) during innate immune regulation. Several NLRs exhibit highly restricted expression in mammalian germline, where their physiological functions are largely unknown. Here we report that Nlrp14, an NLR specifically expressed in testis and ovary, plays a critical role in regulating germ cell differentiation and reproduction. Nlrp14 deficiency led to decreased primordial germ cell-like cell (PGCLC) differentiation in vitro and reproduction failure in both male and female mice in vivo. In the male mice, Nlrp14 knockout strongly compromised differentiation of spermatogonial stem cells and meiosis. Mechanistically, NLRP14 protected HSPA2 from proteasome-mediated degradation by recruiting BAG2, loss of which was further confirmed in a human mutation associated with male sterility.

NOD-like receptors (NLRs) are traditionally recognized as major inflammasome components. The role of NLRs in germ cell differentiation and reproduction is not known. Here, we identified the gonad-specific Nlrp14 as a pivotal regulator in primordial germ cell-like cell (PGCLC) differentiation in vitro. Physiologically, knock out of Nlrp14 resulted in reproductive failure in both female and male mice. In adult male mice, Nlrp14 knockout (KO) inhibited differentiation of spermatogonial stem cells (SSCs) and meiosis, resulting in trapped SSCs in early stages, severe oligozoospermia, and sperm abnormality. Mechanistically, NLRP14 promoted spermatogenesis by recruiting a chaperone cofactor, BAG2, to bind with HSPA2 and form the NLRP14−HSPA2−BAG2 complex, which strongly inhibited ChIP-mediated HSPA2 polyubiquitination and promoted its nuclear translocation. Finally, loss of HSPA2 protection and BAG2 recruitment by NLRP14 was confirmed in a human nonsense germline variant associated with male sterility. Together, our data highlight a unique proteasome-mediated, noncanonical function of NLRP14 in PGCLC differentiation and spermatogenesis, providing mechanistic insights of gonad-specific NLRs in mammalian germline development.

Comparative structure-function features of Hsp70s of Plasmodium falciparum and human origins

The heat shock protein 70 (Hsp70) family of molecular chaperones are crucial for the survival and pathogenicity of the main agent of malaria, Plasmodium falciparum. Hsp70 is central to cellular proteostasis and some of its isoforms are essential for survival of the malaria parasite. In addition, they are also implicated in the development of antimalarial drug resistance. For these reasons, they are thought to be potential drug targets, especially in antimalarial combination therapies. However, their high sequence conservation across species presents a hurdle with respect to their selective targeting. The human genome encodes 17 Hsp70 isoforms while P. falciparum encodes for only 6. The structural architecture of Hsp70s is typically characterized by a highly conserved N-terminal nucleotide-binding domain (NBD) and a less conserved C-terminal substrate-binding domain (SBD). The two domains are connected by a highly conserved linker. In spite of their fairly high sequence conservation, Hsp70s from various species possess unique signature motifs that appear to uniquely influence their function. In addition, their cooperation with co-chaperones further regulates their functional specificity. In the current review, bioinformatics tools were used to identify conserved and unique signature motifs in Hsp70s of P. falciparum versus their human counterparts. We discuss the common and distinctive structure-function features of these proteins. This information is important towards elucidating the prospects of selective targeting of parasite heat shock proteins as part of antimalarial design efforts.

Nuclear localization of EIF4G3 suggests a role for the XY body in translational regulation during spermatogenesis in mice

Eukaryotic translation initiation factor 4G (EIF4G) is an important scaffold protein in the translation initiation complex. In mice, mutation of the Eif4g3 gene causes male infertility, with arrest of meiosis at the end of meiotic prophase. This study documents features of the developmental expression and subcellular localization of EIF4G3 that might contribute to its highly specific role in meiosis and spermatogenesis. Quite unexpectedly, EIF4G3 is located in the nucleus of spermatocytes, where it is highly enriched in the XY body, the chromatin domain formed by the transcriptionally inactive sex chromosomes. Moreover, many other, but not all, translation-related proteins are also localized in the XY body. These unanticipated observations implicate roles for the XY body in controlling mRNA metabolism and/or "poising" protein translation complexes before the meiotic division phase in spermatocytes.

Cancer-testis antigens in ovarian cancer: implication for biomarkers and therapeutic targets

Ovarian cancer remains the most fatal gynecologic malignancy worldwide due to delayed diagnosis as well as recurrence and drug resistance. Thus, the development of new tumor-related molecules with high sensitivity and specificity to replace or supplement existing tools is urgently needed. Cancer-testis antigens (CTAs) are exclusively expressed in normal testis tissues but abundantly found in several types of cancers, including ovarian cancer. Numerous novel CTAs have been identified by high-throughput sequencing techniques, and some aberrantly expressed CTAs are associated with ovarian cancer initiation, clinical outcomes and chemotherapy resistance. More importantly, CTAs are immunogenic and may be novel targets for antigen-specific immunotherapy in ovarian cancer. In this review, we attempt to characterize the expression of candidate CTAs in ovarian cancer and their clinical significance as biomarkers, activation mechanisms, function in malignant phenotypes and applications in immunotherapy.

Heat shock-induced mitotic arrest requires heat shock protein 105 for the activation of spindle assembly checkpoint

Heat shock causes proteotoxic stress that induces various cellular responses, including delayed mitotic progression and the generation of an aberrant number of chromosomes. In this study, heat shock delayed the onset of anaphase by increasing the number of misoriented cells, accompanied by the kinetochore localization of budding uninhibited by benzimidazole-related (BubR)1 in a monopolar spindle (Mps)1-dependent manner. The mitotic delay was canceled by knockdown of mitotic arrest defect (Mad)2. Knockdown of heat shock protein (Hsp)105 partially abrogated the mitotic delay with the loss of the kinetochore localization of BubR1 under heat shock conditions and accelerated mitotic progression under nonstressed conditions. Consistent with this result, Hsp105 knockdown increased the number of anaphase cells with lagging chromosomes, through mitotic slippage, and decreased taxol sensitivity more than Mad2 knockdown. Hsp105 was coprecipitated with cell division cycle (Cdc)20 in an Mps1-dependent manner; however, its knockdown did not affect coprecipitation of Mad2 and BubR1 with Cdc20. We propose that heat shock delays the onset of anaphase via the activation of the spindle assembly checkpoint (SAC). Hsp105 prevents abnormal cell division by contributing to SAC activation under heat shock and nonstressed conditions by interacting with Cdc20 but not affecting formation of the mitotic checkpoint complex.-Kakihana, A., Oto, Y., Saito, Y., Nakayama, Y. Heat shock-induced mitotic arrest requires heat shock protein 105 for the activation of spindle assembly checkpoint.

Cyclin B1/CDK1-regulated mitochondrial bioenergetics in cell cycle progression and tumor resistance

A mammalian cell houses two genomes located separately in the nucleus and mitochondria. During evolution, communications and adaptations between these two genomes occur extensively to achieve and sustain homeostasis for cellular functions and regeneration. Mitochondria provide the major cellular energy and contribute to gene regulation in the nucleus, whereas more than 98% of mitochondrial proteins are encoded by the nuclear genome. Such two-way signaling traffic presents an orchestrated dynamic between energy metabolism and consumption in cells. Recent reports have elucidated the way how mitochondrial bioenergetics synchronizes with the energy consumption for cell cycle progression mediated by cyclin B1/CDK1 as the communicator. This review is to recapitulate cyclin B1/CDK1 mediated mitochondrial activities in cell cycle progression and stress response as well as its potential link to reprogram energy metabolism in tumor adaptive resistance. Cyclin B1/CDK1-mediated mitochondrial bioenergetics is applied as an example to show how mitochondria could timely sense the cellular fuel demand and then coordinate ATP output. Such nucleus-mitochondria oscillation may play key roles in the flexible bioenergetics required for tumor cell survival and compromising the efficacy of anti-cancer therapy. Further deciphering the cyclin B1/CDK1-controlled mitochondrial metabolism may invent effect targets to treat resistant cancers.

Acute Heat Stress Changes Protein Expression in the Testes of a Broiler-Type Strain of Taiwan Country Chickens

Heat stress leads to decreased fertility in roosters. This study investigated the global protein expression in response to acute heat stress in the testes of a broiler-type strain of Taiwan country chickens (TCCs). Twelve 45-week-old roosters were randomly allocated to the control group maintained at 25°C, and three groups subjected to acute heat stress at 38°C for 4 h, with 0, 2, and 6 h of recovery, respectively. Testis samples were collected for hematoxylin and eosin staining, apoptosis assay, and protein analysis. The results revealed 101 protein spots that differed significantly from the control following exposure to acute heat stress. The proteins that were differentially expressed participated mainly in protein metabolism and other metabolic processes, responses to stimuli, apoptosis, cellular organization, and spermatogenesis. Proteins that negatively regulate apoptosis were downregulated and proteins involved in autophagy and major heat shock proteins (HSP90α, HSPA5, and HSPA8) were upregulated in the testes of heat-stressed chickens. In conclusion, acute heat stress causes a change in protein expression in the testes of broiler-type B strain TCCs and may thus impair cell morphology, spermatogenesis, and apoptosis. The expression of heat shock proteins increased to attenuate the testicular injury induced by acute heat stress.

Zipping and Unzipping: Protein Modifications Regulating Synaptonemal Complex Dynamics

The proteinaceous zipper-like structure known as the synaptonemal complex (SC), which forms between pairs of homologous chromosomes during meiosis from yeast to humans, plays important roles in promoting interhomolog crossover formation, regulating cessation of DNA double-strand break (DSB) formation following crossover designation, and ensuring accurate meiotic chromosome segregation. Recent studies are starting to reveal critical roles for different protein modifications in regulating SC dynamics. Protein SUMOylation, N-terminal acetylation, and phosphorylation have been shown to be essential for the regulated assembly and disassembly of the SC. Moreover, phosphorylation of specific SC components has been found to link changes in SC dynamics with meiotic recombination. This review highlights the latest findings on how protein modifications regulate SC dynamics and functions.

Regulating the construction and demolition of the synaptonemal complex

The synaptonemal complex (SC) is a meiosis-specific scaffold that links homologous chromosomes from end to end during meiotic prophase and is required for the formation of meiotic crossovers. Assembly of SC components is regulated by a combination of associated nonstructural proteins and post-translational modifications, such as SUMOylation, which together coordinate the timing between homologous chromosome pairing, double-strand-break formation and recombination. In addition, transcriptional and translational control mechanisms ensure the timely disassembly of the SC after crossover resolution and before chromosome segregation at anaphase I.

Transcriptomic Analysis of Male Black Tiger Shrimp (Penaeus monodon) After Polychaete Feeding to Enhance Testicular Maturation

To reveal molecular mechanism of how polychaetes enhanced reproductive maturation in the male black tiger shrimp (Penaeus monodon), transcriptomic profiles of male reproductive organs (testes and vas deferens) between polychaete-fed and commercial pellet-fed male brooders were compared using cDNA microarray. The overall profiles were distinguishingly different between the two feed groups as well as between testes and vas deferens. Additionally, six of 11 differentially expressed gene identified by the microarray (HNRPUL1 and GCP4 in testes, MAT2B, CDC16, and CSN5 in vas deferens, and SLD5 in both organs) were validated by quantitative real-time PCR (qPCR) and found to exhibit significantly higher expression levels in polychaete-fed shrimp than those in commercial pellet-fed shrimp. From microarray and qPCR results, the differentially expressed transcripts in both testes and vas deferens between different feeds belonged to DNA replication and microtubule nucleation pathways. Interestingly, while the transcripts involved in nutrient uptake and nucleotide biosynthesis were increased only in testes, those involved in protein refolding and apoptosis were increased only in vas deferens. These findings suggest that polychaetes may enhance spermatogenesis by increasing spermatogonia proliferation in testes and by regulating mature spermatozoa in vas deferens.

HSP70-1 is required for interleukin-5-induced angiogenic responses through eNOS pathway

We report a pivotal role for IL-5 as an angiogenic activator. IL-5 increased proliferation, migration and colony tube formation in HUVECs associated with the phosphorylation of ERK and AKT/eNOS, and promoted microvessel sprouting from an angiogenesis animal model. The angiogenic effects were confirmed in IL-5-deficient mice and addition of IL-5 antibody. HSP70-1 was identified via expression profiling following IL-5 stimulation. A siRNA knockdown of HSP70-1 suppressed angiogenic responses and eNOS phosphorylation induced by IL-5. HSP70-1 overexpression enhanced IL-5-induced angiogenic responses. In addition, IL-5-induced neo-vascular formation was verified in both HSP70-1 knockout and HSP70-1 transgenic mice. Furthermore, transcription factor AP-1 was a main factor in IL-5-induced HSP70-1 in response to ERK and AKT signaling pathway. Angiogenic responses induced by VEGF had no effect in either HSP70-1 siRNA in vitro or HSP70-1 knockout mice. IL-5-induced angiogenic responses depended on the binding of IL-5Rα. Our data demonstrate that binding of IL-5 to IL-5Rα receptors enhances angiogenic responses by stimulating the expression of HSP70-1 via the eNOS signaling pathway.

Heat Shock Protein A2 (HSPA2): Regulatory Roles in Germ Cell Development and Sperm Function

Among the numerous families of heat shock protein (HSP) that have been implicated in the regulation of reproductive system development and function, those belonging to the 70 kDa HSP family have emerged as being indispensable for male fertility. In particular, the testis-enriched heat shock 70 kDa protein 2 (HSPA2) has been shown to be critical for the progression of germ cell differentiation during spermatogenesis in the mouse model. Beyond this developmentally important window, mounting evidence has also implicated HSPA2 in the functional transformation of the human sperm cell during their ascent of the female reproductive tract. Specifically, HSPA2 appears to coordinate the remodelling of specialised sperm domains overlying the anterior region of the sperm head compatible with their principle role in oocyte recognition. The fact that levels of the HSPA2 protein in mature spermatozoa tightly correlate with the efficacy of oocyte binding highlight its utility as a powerful prognostic biomarker of male fertility. In this chapter, we consider the unique structural and biochemical characteristics of HSPA2 that enable this heat shock protein to fulfil its prominent roles in orchestrating the morphological differentiation of male germ cells during spermatogenesis as well as their functional transformation during post-testicular sperm maturation.

Heat shock protein 70-2 (HSP70-2) overexpression in breast cancer

Background

Breast cancer is one of the leading cause of cancer-related deaths in women worldwide and increasing rapidly in developing countries. In the present study, we investigated the potential role and association of HSP70-2 with breast cancer.

Methods

HSP70-2 expression was examined in 154 tumor and 103 adjacent non-cancerous tissue (ANCT) specimens and breast cancer cell lines (MCF7, BT-474, SK-BR-3 and MDA-MB-231) by RT-PCR, quantitative-PCR, immunohistochemistry, Western blotting, flow cytometry and indirect immunofluorescence. Plasmid driven short hairpin RNA approach was employed to validate the role of HSP70-2 in cellular proliferation, senescence, migration, invasion and tumor growth. Further, we studied the effect of HSP70-2 protein ablation on signaling cascades involved in apoptosis, cell cycle and Epithelial-Mesenchymal-Transition both in culture as well as in-vivo human breast xenograft mouse model.

Results

HSP70-2 expression was detected in majority of breast cancer patients (83 %) irrespective of various histotypes, stages and grades. HSP70-2 expression was also observed in all breast cancer cells (BT-474, MCF7, MDA-MB-231 and SK-BR-3) used in this study. Depletion of HSP70-2 in MDA-MB-231 and MCF7 cells resulted in a significant reduction in cellular growth, motility, onset of apoptosis, senescence, cell cycle arrest as well as reduction of tumor growth in the xenograft model. At molecular level, down-regulation of HSP70-2 resulted in reduced expression of cyclins, cyclin dependent kinases, anti-apoptotic molecules and mesenchymal markers and enhanced expression of CDK inhibitors, caspases, pro-apoptotic molecules and epithelial markers.

Conclusions

HSP70-2 is over expressed in breast cancer patients and was involved in malignant properties of breast cancer. This suggests HSP70-2 may be potential candidate molecule for development of better breast cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0425-9) contains supplementary material, which is available to authorized users.

Spermatogenesis-associated proteins at different developmental stages of buffalo testicular seminiferous tubules identified by comparative proteomic analysis

The testicular seminiferous tubules contain Sertoli cells and different types of spermatogenic cells. They provide the microenvironment for spermatogenesis, but the precise molecular mechanism of spermatogenesis is still not well known. Here, we have employed tandem mass tag coupled to LC-MS/MS with the high-throughput quantitative proteomics technology to explore the protein expression from buffalo testicular seminiferous tubules at three different developmental stages (prepuberty, puberty, and postpuberty). The results show 304 differentially expressed proteins with a ≥2-fold change, and bioinformatics analysis indicates that 27 of these may be associated with spermatogenesis. Expression patterns of seven selected proteins were verified via Western blot and quantitative RT-PCR analysis, and further cellular localizations of these proteins by immunohistochemical or immunofluorescence analysis. Taken together, the results provide potential molecular markers of spermatogenesis and provide a rich resource for further studies on male reproduction regulation.

The human HSP70 family of chaperones: where do we stand?

The 70-kDa heat shock protein (HSP70) family of molecular chaperones represents one of the most ubiquitous classes of chaperones and is highly conserved in all organisms. Members of the HSP70 family control all aspects of cellular proteostasis such as nascent protein chain folding, protein import into organelles, recovering of proteins from aggregation, and assembly of multi-protein complexes. These chaperones augment organismal survival and longevity in the face of proteotoxic stress by enhancing cell viability and facilitating protein damage repair. Extracellular HSP70s have a number of cytoprotective and immunomodulatory functions, the latter either in the context of facilitating the cross-presentation of immunogenic peptides via major histocompatibility complex (MHC) antigens or in the context of acting as "chaperokines" or stimulators of innate immune responses. Studies have linked the expression of HSP70s to several types of carcinoma, with Hsp70 expression being associated with therapeutic resistance, metastasis, and poor clinical outcome. In malignantly transformed cells, HSP70s protect cells from the proteotoxic stress associated with abnormally rapid proliferation, suppress cellular senescence, and confer resistance to stress-induced apoptosis including protection against cytostatic drugs and radiation therapy. All of the cellular activities of HSP70s depend on their adenosine-5'-triphosphate (ATP)-regulated ability to interact with exposed hydrophobic surfaces of proteins. ATP hydrolysis and adenosine diphosphate (ADP)/ATP exchange are key events for substrate binding and Hsp70 release during folding of nascent polypeptides. Several proteins that bind to distinct subdomains of Hsp70 and consequently modulate the activity of the chaperone have been identified as HSP70 co-chaperones. This review focuses on the regulation, function, and relevance of the molecular Hsp70 chaperone machinery to disease and its potential as a therapeutic target.

Simultaneous Administration of Dexamethasone and Vitamin E Reversed Experimental Varicocele-induced Impact in testicular tissue in Rats; Correlation with Hsp70-2 Chaperone Expression

Purpose:

This study aimed to investigate the protective effects of isolated and co-administration of vitamin E (VitE) and dexamethasone (DEX) on varicocele (VCL)-induced damages in testicular tissue.

Materials and Methods:

Wistar rats were divided into five groups (n=6), including; control-sham, non-treated VCL-induced, VitE-treated VCL-induced (VitE, 150 mg/kg, orally), DEX-administrated VCL-induced (DEX, 0.125 mg/kg, i.p.), VitE+DEX-received VCL-induced animals. The antioxidant status analyses, histopathological examinations, hormonal assay and tissue levels of alkaline phosphatase (ALP) were analyzed. The germinal epithelium RNA damage and Leydig cells steroidogenesis were analyzed. Moreover, the Hsp70-2 protein expression was examined based on immunohistochemical and western blot analyses. The sperm parameters, DNA integrity and chromatin condensation were investigated.

Results:

VitE and DEX in simultaneous form of administration significantly (P<0.05) down-regulated the tissue ALP level and attenuated the VCL-decreased GSH-px, SOD and TAC levels and remarkably (P<0.05) down-regulated the testicular malondialdehyde (MDA) and nitric oxide (NO) contents. The VCL-induced histopathological alterations significantly (P<0.05) improved in VitE and DEX-administrated animals. The VitE and DEX co-administration reduced the VCL-increased RNA damage and elevated the Leydig cells steroidogenic activity. The Hsp70-2 protein level completely (P<0.05) increased in VitE and DEX alone–and-simultaneous-administrated animals. Finally, the VitE and DEX could significantly (P<0.05) improve the VCL-decreased semen quality and improved the sperm DNA integrity and chromatin condensation.

Conclusion:

Our data suggest that Vit E by up-regulating the antioxidant status and DEX by reducing inflammation-dependent oxidative and nitrosative stresses could improve the VCL-reduced Hsp70-2 chaperone expression and ultimately protected the testicular endocrine activities and promoted the spermatogenesis process.

JAG1 Is Associated with Poor Survival through Inducing Metastasis in Lung Cancer

JAG1 is a Notch ligand that plays a critical role in multiple signaling pathways. However, the functionality of JAG1 in non-small cell lung cancer (NSCLC) has not been investigated thoroughly. By comparison of gene transcripted RNA profiles in the cell line pair with differential invasion ability, we identified JAG1 as a potential metastasis enhancer in lung cancer. Ectopic expression of JAG1 on lung cancer cells enhanced cell migration and invasion as well as metastasis in vitro and in vivo. Conversely, knockdown of JAG1 with siRNA in highly invasive cancer cells led to the reduction of migration and invasion. In clinical analysis, JAG1 mRNA expression was higher in tumors than in adjacent normal tissues in 14 of 20 patients with squamous cell carcinoma (SCC). SCC patients with higher JAG1 transcription had poor overall survival than those with low-transcripted JAG1. Microarray analysis indicated that the enforced JAG1 transcription was associated with an elevated HSPA2 RNA transcription, which played a role in promoting cancer cell migration and invasion. In conclusion, this is the first study that demonstrated that JAG1 might act as a potential prognostic marker and JAG1/HSPA2 axis mediates lung cancer malignancy at least partly.

Decreased spermatogenesis led to alterations of testis-specific gene expression in male mice following nano-TiO2 exposure

Although TiO2 nanoparticles (NPs) exposure has been demonstrated to cross blood-testis barrier and accumulate in the testis resulting in the reduction of sperm numbers, limited data with respect to the molecular mechanism of decreased spermatogenesis caused by TiO2 NP exposure. In this research, testicular damage, sperm number and alterations in testis-specific gene expressions in male mice induced by intragastric administration with TiO2 NPs for six months were investigated. It was found out that TiO2 NPs could migrate to cells, deposit in the testis and epididymis and thus cause damages to relevant organs, which are, to be more specific, the reductions of total sperm concentrations and sperm motility and an enhancement in the number of abnormal sperms in the cauda epididymis. Furthermore, the individual expression regarding to the mRNAs and proteins of testis-specific genes, including Cdc2, Cyclin B1, Dmcl, TERT, Tesmin, TESP-1, XPD and XRCCI, were significantly declined, whereas Gsk3-β and PGAM4 expressions were greatly elevated in mouse testis due to the exposures, which in fact implied that the reduced spermatogenesis may be involved in the alternated testis-specific gene expressions in those exposed male mice.

Disrupting Cyclin Dependent Kinase 1 in Spermatocytes Causes Late Meiotic Arrest and Infertility in Mice

While cyclin dependent kinase 1 (CDK1) has a critical role in controlling resumption of meiosis in oocytes, its role has not been investigated directly in spermatocytes. Unique aspects of male meiosis led us to hypothesize that its role is different in male meiosis than in female meiosis. We generated a conditional knockout (cKO) of the Cdk1 gene in mouse spermatocytes to test this hypothesis. We found that CDK1-null spermatocytes undergo synapsis, chiasmata formation, and desynapsis as is seen in oocytes. Additionally, CDK1-null spermatocytes relocalize SYCP3 to centromeric foci, express H3pSer10, and initiate chromosome condensation. However, CDK1-null spermatocytes fail to form condensed bivalent chromosomes in prophase of meiosis I and instead are arrested at prometaphase. Thus, CDK1 has an essential role in male meiosis that is consistent with what is known about the role of CDK1 in female meiosis, where it is required for formation of condensed bivalent metaphase chromosomes and progression to the first meiotic division. We found that cKO spermatocytes formed fully condensed bivalent chromosomes in the presence of okadaic acid, suggesting that cKO chromosomes are competent to condense, although they do not do so in vivo. Additionally, arrested cKO spermatocytes exhibited irregular cell shape, irregular large nuclei, and large distinctive nucleoli. These cells persist in the seminiferous epithelium through the next seminiferous epithelial cycle with a lack of stage XII checkpoint-associated cell death. This indicates that CDK1 is required upstream of a checkpoint-associated cell death as well as meiotic metaphase progression in mouse spermatocytes.

Cytotoxic effect of nanosilver particles on testicular tissue: Evidence for biochemical stress and Hsp70-2 protein expression

Lastly, there are growing evidences that nanosilver (NS) particles highly induce cytotoxic impacts in vitro and in vivo. Here, we analyzed the dose dependent effect of NS on histological changes, biochemical alterations and endocrine statuses, sperm parameters as well as chaperone Hsp70-2 expression. NS particles (50-60nm) were administrated in 3 doses of 0.5, 1 and 5mg/kg, intraperitoneally, for 35 days. The 0.3mL normal saline was administrated in control-sham group. Histological alterations, sperm parameters, serum levels of LH, FSH and testosterone were evaluated. Germinal and Leydig cells RNA damage, Leydig cells steroidogenic foci, the testicular and sperm total antioxidant capacity (TAC), malondialdehyde (MDA), nitric oxide (NO) levels, immunohistochemical (IHC) expression and mRNA level of Hsp70-2 were analyzed. The NS, dose dependently, resulted in enhanced germinal cells degeneration, necrosis, seminiferous tubules atrophy and decreased serum levels of LH, FSH and testosterone. Elevated germinal and Leydig cells RNA damage associated with increased sperm abnormalities were observed in NS-treated groups. Expression of Hsp70-2 was up-regulated in 0.5mg/kg, while its expression was decreased in 1 and 5mg/kg NS-treated groups. Testicular and sperm TAC levels reduced. However, the MDA and NO levels significantly (P<0.05) increased in all NS-treated groups. No histological and biochemical changes were detected in control-sham group. In conclusion, the NS particles exert their pathological impact via affecting testicular antioxidant and endocrine statuses, which in turn lead to diminished expression of Hsp70-2. Ultimately, by this mechanism NS particles adversely impact the cellular RNA, DNA and protein contents.

Expression, function, and regulation of the testis-enriched heat shock HSPA2 gene in rodents and humans

The HSPA2 gene is a poorly characterized member of the HSPA (HSP70) family. HSPA2 was originally described as testis-specific and expressed at the highest level in pachytene spermatocytes of rodents, the expression of which is not induced by heat shock. HSPA2 is crucial for male fertility. However, recent advances have shown that HSPA2 is expressed in various tumors and in certain types of somatic tissues. In this review, we summarize the current knowledge on the HSPA2 expression pattern, including information on transcriptional, translational, posttranslational, and epigenetic mechanisms which regulate HSPA2 expression. We also present and discuss the current views concerning the functions of the HSPA2 protein in spermatogenetic, somatic, and cancer cells. The knowledge of the properties of HSPA2, although limited, shows this protein as a unique member of the HSPA family. However, understanding whether this protein could become a relevant cancer biomarker or a therapeutically applicable target requires extensive further studies.

Targeting the testis-specific heat-shock protein 70-2 (HSP70-2) reduces cellular growth, migration, and invasion in renal cell carcinoma cells

Renal cell carcinoma (RCC) represents one of the most resistant tumors to radiotherapy and chemotherapy. Current therapies for the RCC patients are limited owing to lack of diagnosis and therapeutic treatments. Testis-specific heat-shock protein 70-2 (HSP70-2), a member of HSP70 chaperone family, has been shown to be associated with various cancers. In the present study, we investigated the putative role of HSP70-2 in various malignant properties of the RCC cells. HSP70-2 messenger RNA (mRNA) and protein expression was investigated in A704, ACHN, and Caki-1 cells derived from the RCC patients. We assessed the expression of HSP70-2 gene and protein by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The expression of HSP70-2 protein was further validated by performing indirect immunofluorescence (IIF) and flow cytometry. The malignant properties of high-grade invasive A704 and Caki-1 cells, such as cellular proliferation, colony formation, migration, invasion, and wound healing, were evaluated by silencing the expression of HSP70-2 gene in these cells. Statistical significance was defined using Student's t test. Our RT-PCR and Western blotting data showed the expression of HSP70-2 in all RCC cells. Our results showed that HSP70-2 was predominantly expressed in cytoplasm and found to be colocalized with endoplasmic reticulum, mitochondria, Golgi body, and plasma membrane but not the nuclear envelope. Knockdown of HSP70-2 expression with specific short hairpin RNA (shRNA) demonstrated significant reduction in cell growth and colony formation. Further, a marked reduction in cell migration and invasion was also observed, indicating the potential role of HSP70-2 in metastasis. Collectively, our data suggest that HSP70-2 plays a key role in cancerous growth and invasive potential of RCC cells. Thus, HSP70-2 could serve as a novel potential therapeutic target for the RCC.

HSP70-binding protein HSPBP1 regulates chaperone expression at a posttranslational level and is essential for spermatogenesis

Molecular chaperones play key roles during growth, development, and stress survival. The ability to induce chaperone expression enables cells to cope with the accumulation of nonnative proteins under stress and complete developmental processes with an increased requirement for chaperone assistance. Here we generate and analyze transgenic mice that lack the cochaperone HSPBP1, a nucleotide-exchange factor of HSP70 proteins and inhibitor of chaperone-assisted protein degradation. Male HSPBP1(-/-) mice are sterile because of impaired meiosis and massive apoptosis of spermatocytes. HSPBP1 deficiency in testes strongly reduces the expression of the inducible, antiapoptotic HSP70 family members HSPA1L and HSPA2, the latter of which is essential for synaptonemal complex disassembly during meiosis. We demonstrate that HSPBP1 affects chaperone expression at a posttranslational level by inhibiting the ubiquitylation and proteasomal degradation of inducible HSP70 proteins. We further provide evidence that the cochaperone BAG2 contributes to HSP70 stabilization in tissues other than testes. Our findings reveal that chaperone expression is determined not only by regulated transcription, but also by controlled degradation, with degradation-inhibiting cochaperones exerting essential prosurvival functions.

Aquaporin-11 control of testicular fertility markers in Syrian hamsters

The present study sought novel changes to the hamster testicular transcriptome during modulation of fertility by well-characterized photoperiodic stimuli. Transition from long days (LD, 14 h light/day) to short days (SD, 10h light/day) triggered testicular regression (61% reduction of testis weight, relative to LD) in SD-sensitive (SD-S) hamsters within 16 weeks. After 22 weeks of SD exposure, a third cohort of hamsters became SD-refractory (SD-R), and exhibited testicular recrudescence (137% testis weight gain, relative to SD-S). Partial interrogation of the testicular transcriptome by annealing-control-primer-modified differential display PCR provided several candidates for regulation of testicular functions. Multiple linear regression modeling indicated the best correlation for aquaporin 11 (Aqp11) with changes in testis weight. Correlations were also strongest for Aqp11 with expression levels of reference cDNAs that control spermatogenesis (Hspa2 and Tnp2), steroidogenesis (Cox2, 3βHsd, and Srebp2), sperm motility (Catsper1, Pgk2, and Tnp2), inflammation (Cox2), and apoptosis (Bax and Bcl2). Moreover, siRNA-mediated knockdown of testicular Aqp11 mRNA and protein reduced Hspa2 and Tnp2 mRNA levels, and it increased 3βHsd mRNA levels. It also reduced mRNA levels for Sept12, which is a testis-specific inducer of spermatogenesis. These results suggest a central role for testicular Aqp11 signaling in the coordinate regulation of crucial components of fertility.

iTRAQ-based quantitative proteomics analysis revealed alterations of carbohydrate metabolism pathways and mitochondrial proteins in a male sterile cybrid pummelo

Comprehensive and quantitative proteomic information on citrus floral bud is significant for understanding male sterility of the cybrid pummelo (G1+HBP) with nuclear genome of HBP and foreign mitochondrial genome of G1. Scanning electron microscopy and transmission electron microscopy analyses of the anthers showed that the development of pollen wall in G1+HBP was severely defective with a lack of exine and sporopollenin formation. Proteomic analysis was used to identify the differentially expressed proteins between male sterile G1+HBP and fertile type (HBP) with the aim to clarify their potential roles in anther development and male sterility. On the basis of iTRAQ quantitative proteomics, we identified 2235 high-confidence protein groups, 666 of which showed differentially expressed profiles in one or more stages. Proteins up- or down-regulated in G1+HBP were mainly involved in carbohydrate and energy metabolism (e.g., pyruvate dehydrogenase, isocitrate dehydrogenase, ATP synthase, and malate dehydrogenase), nucleotide binding (RNA-binding proteins), protein synthesis and degradation (e.g., ribosome proteins and proteasome subunits). Additionally, the proteins located in mitochondria also showed changed expression patterns. These findings provide a valuable inventory of proteins involved in floral bud development and contribute to elucidate the mechanism of cytoplasmic male sterility in the cybrid pummelo.

Cell cycle regulators guide mitochondrial activity in radiation-induced adaptive response

SIGNIFICANCE

There are accruing concerns on potential genotoxic agents present in the environment including low-dose ionizing radiation (LDIR) that naturally exists on earth's surface and atmosphere and is frequently used in medical diagnosis and nuclear industry. Although its long-term health risk is being evaluated and remains controversial, LDIR is shown to induce temporary but significant adaptive responses in mammalian cells and animals. The mechanisms guiding the mitochondrial function in LDIR-induced adaptive response represent a unique communication between DNA damage and cellular metabolism. Elucidation of the LDIR-regulated mitochondrial activity may reveal new mechanisms adjusting cellular function to cope with hazardous environmental stress.

RECENT ADVANCES

Key cell cycle regulators, including Cyclin D1/CDK4 and Cyclin B1/cyclin-dependent kinase 1 (CDK1) complexes, are actively involved in the regulation of mitochondrial functions via phosphorylation of their mitochondrial targets. Accumulating new evidence supports a concept that the Cyclin B1/CDK1 complex acts as a mediator in the cross talk between radiation-induced DNA damage and mitochondrial functions to coordinate cellular responses to low-level genotoxic stresses.

CRITICAL ISSUES

The LDIR-mediated mitochondrial activity via Cyclin B1/CDK1 regulation is an irreplaceable network that is able to harmonize vital cellular functions with adjusted mitochondrial metabolism to enhance cellular homeostasis.

FUTURE DIRECTIONS

Further investigation of the coordinative mechanism that regulates mitochondrial activities in sublethal stress conditions, including LDIR, will reveal new insights of how cells cope with genotoxic injury and will be vital for future targeted therapeutic interventions that reduce environmental injury and cancer risk.

SHCBP1L, a conserved protein in mammals, is predominantly expressed in male germ cells and maintains spindle stability during meiosis in testis

Male subfertility due to falling sperm counts has become an increasing problem over a short timescale (50-70 years). Recently, bioinformatics analysis of the human testis proteome has revealed the existence of human-testicular-predominantly-expressed-proteins, which are highly associated with spermatogenesis, although the functions of many of these proteins are still unknown. To understand the function of one of these proteins, SHCBP1L (1700012A16RIKEN), a knockout mouse was produced in which this gene was removed. Using this model, we showed that SHCBP1L binds to another protein, HSPA2, and maintains stability of the spindle. We showed that this complex was not present in knockout mice and that an abnormal number of spermatocytes were held in the early stages of meiosis. Many of these cells were undergoing programmed cell-death, or apoptosis, which is highly unusual for cells during the early stages of meiosis. We also found that proteins very similar to SHCBP1L exist in many other mammals. This led us to propose that SHCBP1L plays an important role in spermatogenesis in mammals.

The APC/C activator FZR1 is essential for meiotic prophase I in mice

Fizzy-related 1 (FZR1) is an activator of the Anaphase promoting complex/cyclosome (APC/C) and an important regulator of the mitotic cell division cycle. Using a germ-cell-specific conditional knockout model we examined its role in entry into meiosis and early meiotic events in both sexes. Loss of APC/C(FZR1) activity in the male germline led to both a mitotic and a meiotic testicular defect resulting in infertility due to the absence of mature spermatozoa. Spermatogonia in the prepubertal testes of such mice had abnormal proliferation and delayed entry into meiosis. Although early recombination events were initiated, male germ cells failed to progress beyond zygotene and underwent apoptosis. Loss of APC/C(FZR1) activity was associated with raised cyclin B1 levels, suggesting that CDK1 may trigger apoptosis. By contrast, female FZR1Δ mice were subfertile, with premature onset of ovarian failure by 5 months of age. Germ cell loss occurred embryonically in the ovary, around the time of the zygotene-pachytene transition, similar to that observed in males. In addition, the transition of primordial follicles into the growing follicle pool in the neonatal ovary was abnormal, such that the primordial follicles were prematurely depleted. We conclude that APC/C(FZR1) is an essential regulator of spermatogonial proliferation and early meiotic prophase I in both male and female germ cells and is therefore important in establishing the reproductive health of adult male and female mammals.

Testosterone and vitamin E administration up-regulated varicocele-reduced Hsp70-2 protein expression and ameliorated biochemical alterations

PURPOSE

This study was designed to evaluate the protective effects of vitamin E (VitE) and testosterone on varicocele (VCL)-induced damage in testis and sperm parameters and their effects on Hsp70-2 chaperone expression and on antioxidant status.

METHODS

Wistar rats were divided into five groups: control-sham, VCL-induced, VitE-treated varicocelized (150 mg/kg, orally), testosterone-administrated varicocelized (400 μg/kg, intraperitoneally) and VitE + testosterone-received VCL-induced rats. The sperm count, DNA integrity, motility, viability and histone-protamine transition were evaluated after 60 days. The antioxidant status was analyzed by determining testicular malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide desmutase (SOD) and glutathione peroxidase (GSH-Px). Endocrine status of the testicular tissue was estimated by evaluating the Leydig cells steroidogenic activity using fluorescent analyses for cytoplasmic steroid foci and by determination of serum testosterone. The expression of Hsp70-2 protein was analyzed using imunohistochemical and western blot analyses. RNA damage of the germinal cells was examined with epi-fluorescent examination.

RESULTS

VitE and testosterone administration ameliorated the varicocele-reduced Leydig cell and testosterone level. In addition, co-administration of these compounds recovered the VCL-induced reduction of TAC, SOD, and GSH-px and lowered significantly (P < 0.05) the VCL-elevated content of MDA. The treated animals revealed with a significant (P < 0.05) up-regulation of the VCL-reduced expression of Hsp70-2 protein. Moreover, VitE and testosterone significantly (P < 0.05) inhibited the VCL-increased RNA damage in germinal cells.

CONCLUSION

Our data suggest that the protective effects of VitE and testosterone on VCL-induced derangements may depend on enhancing testicular antioxidant status and up-regulating endocrine activities, which enhanced the Hsp70-2 chaperone expression.

Comparison of the activity of three different HSP70 inhibitors on apoptosis, cell cycle arrest, autophagy inhibition, and HSP90 inhibition

The chaperone HSP70 promotes the survival of cells exposed to many different types of stresses, and is also potently anti-apoptotic. The major stress-induced form of this protein, HSP70-1, is overexpressed in a number of human cancers, yet is negligibly expressed in normal cells. Silencing of the gene encoding HSP70-1 (HSPA1A) is cytotoxic to transformed but not normal cells. Therefore, HSP70 is considered to be a promising cancer drug target, and there has been active interest in the identification and characterization of HSP70 inhibitors for cancer therapy. Because HSP70 behaves in a relatively non-specific manner in the control of protein folding, to date there are no reliably-identified "clients" of this protein, nor is there consensus as to what the phenotypic effects of HSP70 inhibitors are on a cancer cell. Here for the first time we compare three recently-identified HSP70 inhibitors, PES-Cl, MKT-077, and Ver-155008, for their ability to impact some of the known and reported functions of this chaperone; specifically, the ability to inhibit autophagy, to influence the level of HSP90 client proteins, to induce cell cycle arrest, and to inhibit the enzymatic activity of the anaphase-promoting complex/cyclosome (APC/C). We report that all three of these compounds can inhibit autophagy and cause reduced levels of HSP90 client proteins; however, only PES-Cl can inhibit the APC/C and induce G 2/M arrest. Possible reasons for these differences, and the implications for the further development of these prototype compounds as anti-cancer agents, are discussed.

Overexpression of HSPA2 is correlated with poor prognosis in esophageal squamous cell carcinoma

Background

Heat shock-related 70 kDa protein 2 (HSPA2) has been identified as a potential cancer-promoting protein expressed at abnormal levels in a subset of cancers. However, its important role in esophageal squamous cell carcinoma (ESCC) is hardly known by people. The purpose of this study is to assess HSPA2 expression and to explore its role in ESCC.

Methods

Thirty ESCC samples, paired adjacent non-cancerous tissues and normal esophageal tissues, were collected for HSPA2 detection by quantitative RT-PCR (qRT-PCR) and western blotting. Additionally, the expression of HSPA2 in ESCC and adjacent non-cancerous tissues from 120 patients was analyzed by immunohistochemistry, and correlated with clinicopathological parameters and patients’ outcome.

Results

HSPA2 mRNA and protein were overexpressed in ESCC tissues. Overexpression of HSPA2 was significantly associated with primary tumor, TNM stage, lymph node metastases and recurrence, respectively (all, P <0.05). Kaplan-Meier curves showed that elevated HSPA2 expression was associated with shorter disease-free survival and overall survival in ESCC patients. Cox multivariate regression analysis revealed that overexpression of HSPA2 was an independent prognostic factor in disease-free survival and overall survival for ESCC patients (hazard ratio was 2.115 and 2.210, respectively, P <0.05).

Conclusions

Our findings demonstrate that overexpression of HSPA2 may contribute to the malignant progression of ESCC and present a novel prognostic indicator for ESCC patients.

N,N'-dinitrosopiperazine--mediated heat-shock protein 70-2 expression is involved in metastasis of nasopharyngeal carcinoma

N,N′-Dinitrosopiperazine (DNP) is invovled in nasopharyngeal carcinoma (NPC) development and metastasis, and it shows organ specificity to the nasopharyngeal epithelium. Herein, we demonstrate that DNP induces heat-shock protein (HSP) 70-2 expression in NPC cells (6-10B) at a non-cytotoxic concentration. DNP induced HSP70-2 expression in a dose- and time- dependent manner, but showed no effect on other HSP70 family members. Furthermore, DNP also increased HSP70-2 RNA transcription through directly binding to the hypoxia-responsive elements (HRE) and heat shock elements (HSE) located in the HSP70-2 promoter. DNP-mediated HSP70-2 expression might act through enhancing the transcription of HSP70-2 RNA. Importantly, DNP induced motility and invasion of 6-10B cells dose- and time-dependently, and DNP-mediated NPC metastasis was confirmed in nude mice, which showed high HSP70-2 expression in the metastatic tumor tissue. However, the motility and invasion of NPC cells that were stably transfected using short interfering RNA against HSP70-2 could not effectively induce DNP. These results indicate that DNP induces HSP70-2 expression through increasing HSP70-2 transcription, increases the motility and invasion of cells, and promotes NPC tumor metastasis. Therefore, DNP mediated HSP70-2 expression may be an important factor of NPC-high metastasis.