YES1 activation elicited by heat stress is anti-apoptotic in mouse pachytene spermatocytes

Heat-induced increases in body temperature in lactating dairy cows: impact on the cumulus and granulosa cell transcriptome of the periovulatory follicle

Cows acutely heat stressed after a pharmacologically induced luteinizing hormone (LH) surge had periovulatory changes in the follicular fluid proteome that may potentiate ovulation and impact oocyte developmental competence. Because the cellular origins of differentially abundant proteins were not known, we have examined the cumulus and granulosa cell transcriptomes from the periovulatory follicle in cows exhibiting varying levels of hyperthermia when occurring after the LH surge. After pharmacological induction of a dominant follicle, lactating dairy cows were administered gonadotropin releasing hormone (GnRH) and maintained in thermoneutral conditions (~67 temperature-humidity index [THI]) or heat stress conditions where THI was steadily increased for ~12 h (71 to 86 THI) and was sufficient to steadily elevate rectal temperatures. Cumulus-oocyte complexes and mural granulosa cells were recovered by transvaginal aspiration of dominant follicle content ~16 h after GnRH. Rectal temperature was used as a continuous, independent variable to identify differentially expressed genes (DEGs) increased or decreased per each 1 °C change in temperature. Cumulus (n = 9 samples) and granulosa (n = 8 samples) cells differentially expressed (false discovery rate [FDR] < 0.05) 25 and 87 genes, respectively. The majority of DEGs were upregulated by hyperthermia. Steady increases in THI are more like the "turning of a dial" than the "flipping of a switch." The moderate but impactful increases in rectal temperature induced modest fold changes in gene expression (<2-fold per 1 °C change in rectal temperature). Identification of cumulus DEGs involved in cell junctions, plasma membrane rafts, and cell-cycle regulation are consistent with marked changes in the interconnectedness and function of cumulus after the LH surge. Depending on the extent to which impacts may be occurring at the junctional level, cumulus changes may have indirect but impactful consequences on the oocyte as it undergoes meiotic maturation. Two granulosa cell DEGs have been reported by others to promote ovulation. Based on what is known, several other DEGs are suggestive of impacts on collagen formation or angiogenesis. Collectively these and other findings provide important insight regarding the extent to which the transcriptomes of the components of the periovulatory follicle (cumulus and mural granulosa cells) are affected by varying degrees of hyperthermia.

TNF-α/ENO1 signaling facilitates testicular phagocytosis by directly activating Elmo1 gene expression in mouse Sertoli cells

Phagocytic clearance of apoptotic germ cells (GCs), as well as residual bodies (RBs) released from developing spermatids, is critical for Sertoli cells (SCs) to maintain inner environment homeostasis within testis. However, the molecular mechanisms controlling the phagocytosis are ill defined. Here, we identify a new role for alpha-enolase (ENO1), a key enzyme during glycolysis, as a molecule that facilitates testicular phagocytosis via transactivation of the engulfment and cell motility 1 (Elmo1) gene. Using immunohistochesmitry and double-labeling immunofluorescence, ENO1 was observed to be expressed exclusively in the nuclei of SCs and its expression correlated with the completion of Sertoli cell differentiation. By incubating TM4 cells with different pharmacological inhibitors and establishing TM4^Tnfr1-/- cells, we demonstrated that Sertoli cell-specific expression of ENO1 was under a delicate paracrine control from apoptotic GCs. In turn, persistent blockade of ENO1 expression by a validated siRNA protocol resulted in the disturbance of spermatogenesis and impairment of male fertility. Furthermore, using chromatin immunoprecipitation, electrophoretic mobility shift assay and luciferase reporter assay, we showed that in the presence of apoptotic GCs, ENO1 binds to the distal region of the Elmo1 promoter and facilitates transactivation of the Elmo1 gene. In agreement, overexpression of ELMO1 ameliorated ENO1 deficiency-induced impairment of phagocytosis in TM4 cells. These data reveal a novel role for Sertoli cell-specific expression of ENO1 in regulating phagocytosis in testis, identify TNF-α and ELMO1 as critical upstream and downstream factors in mediating ENO1 action, and have important implications for understanding paracrine control of Sertoli cell function by adjacent GCs.

Responses and coping methods of different testicular cell types to heat stress: overview and perspectives

To facilitate temperature adjustments, the testicles are located outside the body cavity. In most mammals, the temperature of the testes is lower than the body temperature to ensure the normal progression of spermatogenesis. Rising temperatures affect spermatogenesis and eventually lead to a decline in male fertility or even infertility. However, the testes are composed of different cell types, including spermatogonial stem cells (SSCs), spermatocytes, spermatozoa, Leydig cells, and Sertoli cells, which have different cellular responses to heat stress. Recent studies have shown that using different drugs can relieve heat stress-induced reproductive damage by regulating different signaling pathways. Here, we review the mechanisms by which heat stress damages different cells in testes and possible treatments.

Potentiation of cancerous progression by LISCH7 via direct stimulation of TGFB1 transcription in triple-negative breast cancer

As an aggressive breast cancer (BCa) subtype, triple-negative breast cancer (TNBC) responses poorly to chemotherapy and endocrine therapy, and usually has a worse prognosis. This is largely due to the lack of specific therapeutic targets, laying claim to an imperious demand to clarify the key signaling pathways potentiating TNBC progression. Herein, we report that expression levels of the liver-specific bHLH-Zip transcription factor (LISCH7), a recently identified key player in cancerous progression, preferentially enriched in TNBC in comparison with other BCa subtypes, and this upregulation was observed to be correlated to a poor survival outcome in patients with TNBC. Ablation of LISCH7 in TNBC cells impaired cell proliferation, reduced cell invasiveness, and enhanced sensitivity to the first-line chemotherapeutic drug docetaxel at both in vitro and in vivo levels. Importantly, concurrent induction of TGFB1, the gene encoding transforming growth factor-β1 (TGF-β1), an essential multipluripotent regulator of TNBC, was accompanied with these alterations in cancerous properties. We further showed that LISCH7 could directly bind to the TGFB1 promoter and stimulate TGFB1 transcription in TNBC cells. The recruitment of LISCH7 onto the TGFB1 chromatin and transactivation of TGFB1 were substantially augmented by treatment with the exogenous TGF-β1 in a time- and dose-dependent manner. Collectively, these findings suggest that LISCH7 and TGF-β1 form a reciprocal positive regulatory loop and cooperatively regulate cancerous progression in TNBC cells. Thus, simultaneous inhibition of both LISCH7 and TGF-β1 signaling may represent a more effective approach to counteract advanced TNBC.

Hyperinsulinemia-induced KLF5 mediates endothelial angiogenic dysfunction in diabetic endothelial cells

Reduced expression of endothelial nitric oxide synthase (eNOS) is a hallmark of endothelial dysfunction in diabetes, which predisposes diabetic patients to numerous cardiovascular complications including blunted angiogenesis. The Krüppel-like factor (KLF) five has been implicated as a central regulator of cardiovascular remodeling, but its role in endothelial cells (ECs) remains poorly understood. We show here that expression of endothelial KLF5 was significantly increased in the ECs from mouse diabetes mellitus type 2 (T2DM) model, when compared to non-diabetic or T1DM mouse. KLF5 up-regulation by insulin was dependent on activation of multiple pathways, including mammalian target of rapamycin, oxidative stress and Protein kinase C pathways. Hyperinsulinemia-induced KLF5 inhibited endothelial function and migration, and thereby compromised in vitro and in vivo angiogenesis. Mechanistically, KLF5 acted in concert with the MTA1 coregulator to negatively regulate NOS3 transcription, thereby leading to the diminished eNOS levels in ECs. Conversely, potentiation of cGMP content (the essential downstream effector of eNOS signaling) by pharmacological approaches successfully rescued the endothelial proliferation and in vitro tube formation, in the HUVECs overexpressing the exogenous KLF5. Collectively, the available data suggest that the augmentation of endothelial KLF5 expression by hyperinsulinemia may represent a novel mechanism for negatively regulating eNOS expression, and may thus help to explain for the T2DM-related endothelial dysfunction at the transcriptional level.

ERK1/2 regulates heat stress-induced lactate production via enhancing the expression of HSP70 in immature boar Sertoli cells

Lactate produced by Sertoli cells plays an important role in spermatogenesis, and heat stress induces lactate production in immature boar Sertoli cells. Extracellular signaling regulated kinase 1 and 2 (ERK1/2) participates in heat stress response. However, the effect of ERK1/2 on heat stress-induced lactate production is unclear. In the present study, Sertoli cells were isolated from immature boar testis and cultured at 32 °C. Heat stress was induced in a 43 °C incubator for 30 min. Proteins and RNAs were detected by western blotting and RT-PCR, respectively. Lactate production and lactate dehydrogenase (LDH) activity were detected using commercial kits. Heat stress promoted ERK1/2 phosphorylation, showing a reducing trend with increasing recovery time. In addition, heat stress increased heat shock protein 70 (HSP70), glucose transporter 3 (GLUT3), and lactate dehydrogenase A (LDHA) expressions, enhanced LDH activity and lactate production at 2-h post-heat stress. Pretreatment with U0126 (1 × 10-6 mol/L), a highly selective inhibitor of ERK1/2 phosphorylation, reduced HSP70, GLUT3, and LDHA expressions and decreased LDH activity and lactate production. Meanwhile, ERK2 siRNA1 reduced the mRNA level of ERK2 and weakened ERK1/2 phosphorylation. Additionally, ERK2 siRNA1 reduced HSP70, GLUT3, and LHDA expressions decreased LDH activity and lactate production. Furthermore, HSP70 siRNA3 downregulated GLUT3 and LDHA expressions and decreased LDH activity and lactate production. These results show that activated ERK1/2 increases heat stress-induced lactate production by enhancing HSP70 expression to promote the expressions of molecules related to lactate production (GLUT3 and LDHA). Our study reveals a new insight in reducing the negative effect of heat stress in boars.

Protective effects of camel whey protein against scrotal heat-mediated damage and infertility in the mouse testis through YAP/Nrf2 and PPAR-gamma signaling pathways

Elevation of scrotal temperature is one of the most important causes of impaired spermatogenesis and male infertility, but the exact mechanism remains controversial. The present study investigated the impact of camel whey protein (CWP) on the mechanisms of heat stress (HS)-mediated testicular damage in male mice. Exposure to HS was associated with significant increase in the testicular tissues' oxidative stress. Mechanistically, exposure to HS resulted in upregulation of P53 and Nrf2 expressions; downregulation of Bcl2 and PPAR-γ expressions; and induction of testicular Leydig cell hyperplasia. Because Leydig cells produce testosterone up on stimulation with Luteinizing hormone (LH), HS mice also exhibited significant reduction in the serum testosterone levels followed by significant reduction in the percentages of progressively motile sperm and higher percentages of immotile sperm, when compared with those of control mice. Interestingly, treatment of HS mice with CWP significantly restored the levels of ROS and the activities of antioxidant enzymes in the testicular tissues nearly to those observed in control mice. Furthermore, CWP supplemented HS mice exhibited complete restoration of Bcl2, P53, Nrf2, and PPAR-γ expressions; testicular Leydig cell distribution; significant higher levels of testosterone levels; and hence higher percentages of progressively motile sperm and lower percentages of immotile sperm as compared to HS mice. Our findings reveal the protective effects of CWP against testis injury and infertility induced by exposure to HS by rescuing functional Leydig cells. Additionally, the present study has shed light on the molecular mechanisms underlying improved testicular damage following CWP treatment.

miR-1271 inhibits ERα expression and confers letrozole resistance in breast cancer

Attenuation of estrogen receptor α (ERα) expression via unknown mechanism(s) is a hallmark of endocrine-resistant breast cancer (BCa) progression. Here, we report that miR-1271 was significantly down-regulated in letrozole-resistant BCa tissues and in letrozole-resistant BCa cells. miR-1271 directly targeted the chromatin of DNA damage-inducible transcript 3 (DDIT3) gene. miR-1271 expression level was inversely correlated to DDIT3 mRNA level in BCa biopsies. Form a mechanistic standpoint, reintroduction of exogenous miR-1271 could effectively restore ERα level via inhibiting DDIT3 expression, thereby potentiating letrozole sensitivity in BCa cells. Moreover, DDIT3 deregulation promoted letrozole-resistance by acting as a potent corepressor of ESR1 transcription. Taken together, we have identified that disruption of the miR-1271/DDIT3/ERα cascade plays a causative role in the pathogenesis of letrozole resistance in BCa.

Regulation of Docetaxel Sensitivity in Prostate Cancer Cells by hsa-miR-125a-3p via Modulation of Metastasis-Associated Protein 1 Signaling

OBJECTIVE

To identify the potential downstream targets of hsa-miR-125a-3p, a mature form of miR-125a, during the pathogenesis of chemoresistance in prostate cancer (PCa).

MATERIALS AND METHODS

The expression levels of hsa-miR-125a-3p were assessed in chemoresistant PCa tissues and experimentally established chemoresistant cells using quantitative reverse transcription-polymerase chain reaction. The effect of hsa-miR-125a-3p knockdown or hsa-miR-125a-3p overexpression on the Dox-induced cell death was evaluated using apoptosis ELISA in chemosensitive PC-3 cells or in chemoresistant PC-3 cells (PC-3R). Finally, using multiple assays, the regulation of metastasis-associated protein 1 (MTA1), an essential component of the Mi-2-nucleosome remodeling deacetylation complex, by hsa-miR-125a-3p was studied at both molecular and functional levels.

RESULTS

The expression of hsa-miR-125a-3p was significantly downregulated in chemoresistant PCa tissues and cells. Inhibition of hsa-miR-125a-3p significantly increased docetaxel (Dox) resistance in PC-3 cells, whereas upregulation of hsa-miR-125a-3p effectively reduced Dox resistance in PC-3R, suggesting that this microRNA (miRNA) may act as a tumor suppressor along the pathogenesis of drug resistance. Mechanistically, hsa-miR-125a-3p induced apoptosis and Dox sensitivity in PCa cells through regulating MTA1.

CONCLUSION

Our results collectively indicate that miRNA-MTA1 can form a delicate regulatory loop to maintain a bistable state in the Dox chemosensitivity, and future endeavor in this filed should provide important clues to develop miRNA-based therapies that benefit advanced PCa patients through modulating the functional status of MTA1.

Potentiation of docetaxel sensitivity by miR-638 via regulation of STARD10 pathway in human breast cancer cells

Acquired resistance to classical chemotherapeutics such as docetaxel (DTX) remains a critical challenge in breast cancer (BCa) treatment. Epigenetic modification by microRNAs (miRNAs) has been shown to play a crucial role in cancer drug resistance. Previous study, using human drug-resistant BCa tissues, has identified miR-638 as one of the most down-regulated miRNAs, but its exact roles and underlying mechanisms during the pathogenesis of chemoresistance remain to be determined. In the current study, we found that miR-638 expression was significantly down-regulated in clinical DTX-resistant BCa tissues compared to that in DTX-sensitive BCa tissues. By using the previously established DTX-resistant MCF-7 cells (MCF-7/R), we also confirmed that chemoresistant cells displayed decreased levels of miR-638. To provide the direct functional evidence, we inhibited and overexpressed miR-638 in different cell lines. Thereby, the cells were rendered more resistant or susceptible to DTX treatment. Mechanistically, the lipid-binding protein STARD10 was identified as a miR-638 target mediating the DTX-resistance. Hence, we provide a molecular explanation for acquired resistance to DTX that is caused by the miR-638 deficiency and subsequent STARD10 upregulation. In consequence, alteration of miR-638/STARD10 cascade may represent an attractive strategy in future adjuvant therapy along with DTX chemotherapy.

The calcium-sensing receptor participates in testicular damage in streptozotocin-induced diabetic rats

Male infertility caused by testicular damage is one of the complications of diabetes mellitus. The calcium-sensing receptor (CaSR) is expressed in testicular tissues and plays a pivotal role in calcium homeostasis by activating cellular signaling pathways, but its role in testicular damage induced by diabetes remains unclear. A diabetic model was established by a single intraperitoneal injection of streptozotocin (STZ, 40 mg kg⁻¹) in Wistar rats. Animals then received GdCl₃ (an agonist of CaSR, 8.67 mg kg⁻¹), NPS-2390 (an antagonist of CaSR, 0.20 g kg⁻¹), or a combination of both 2 months after STZ injection. Diabetic rats had significantly lower testes weights and serum levels of testosterone compared to healthy rats, indicating testicular damage and dysfunction in STZ-induced diabetic rats. Compared with healthy controls, the testicular tissues of diabetic rats overexpressed the CaSR protein and had higher levels of malondialdehyde (MDA), lower superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity, and higher numbers of apoptotic germ cells. The testicular tissues from diabetic rats also expressed lower levels of Bcl-2 and higher levels of Bax and cleaved caspase-3 in addition to higher phosphorylation rates of c-Jun NH₂-terminal protein kinase (JNK), p38, and extracellular signaling-regulated kinase (ERK) 1/2. The above parameters could be further increased or aggravated by the administration of GdCl₃, but could be attenuated by injection of NPS-2390. In conclusion, the present results indicate that CaSR activation participates in diabetes-induced testicular damage, implying CaSR may be a potential target for protective strategies against diabetes-induced testicular damage and could help to prevent infertility in diabetic men.

Suppression of EIF4G2 by miR-379 potentiates the cisplatin chemosensitivity in nonsmall cell lung cancer cells

Although microRNAs and EIF4G2 are both known to play pivotal roles in cancer progression, it remains unknown whether these pathways regulate chemosensitivity in a coordinated manner. Here, we show that miR-379 expression is significantly downregulated in chemoresistant nonsmall cell lung cancer (NSCLC) tissues and cells. Manipulation of miR-379 levels could alter the in vitro and in vivo cisplatin (CDDP) resistance in lung cancer (LCa) cells. Mechanistically, miR-379 potentiated LCa chemosensitivity via modulation of CDDP-induced apoptosis by directly targeting the EIF4G2 3'UTR. Additionally, we observed an inverse correlation between miR-379 and EIF4G2 expression in LCa tissues from patients with CDDP-based chemotherapy. Together, our findings shed new light on the potential involvement of miR-379/EIF4G2 cascade in the pathogenesis of CDDP resistance in LCa.

Regulation of cancerous progression and epithelial-mesenchymal transition by miR-34c-3p via modulation of MAP3K2 signaling in triple-negative breast cancer cells

Emerging but limited data have evidenced an essential involvement of microRNAs (miRNAs) in the development and progression of triple negative breast cancer (TNBC), which empowers these small regulators as an innovative therapeutic approach, especially for this unique tumor subgroup still lacking an efficient and specific therapeutic target. Herein, we reported the down-regulation of miR-34c-3p level in TNBC tissues, and its expression was closely associated with estrogen receptor alpha (ERα), but not other receptors, in well-characterized breast cancer (BCa) cells. Functionally, ectopic expression of miR-34c-3p inhibited migration, invasion and epithelial-mesenchymal transition (EMT) in TNBC cells. From a mechanistic standpoint, bioinformatics coupled with luciferase and gain-of-function, loss-of-function assays showed that miR-34c-3p may regulate TNBC progression by directly targeting the 3'-untranslated region (UTR) of mitogen-activated protein kinase kinase kinase 2 (MAP3K2). Consistently, MAP3K2 overexpression could effectively rescue miR-34c-3p mimics-induced suppression of cell invasion and EMT. In light of these findings, miR-34c-3p may function as a tumor suppressor in regulating of TNBC invasiveness and EMT through negatively modulating MAP3K2 pathway. Future endeavor in this field may help to identify a novel biomarker to predict prognosis and response to therapy in TNBC.

Repression of neuronal nitric oxide (nNOS) synthesis by MTA1 is involved in oxidative stress-induced neuronal damage

The Metastasis-associated protein 1 (MTA1) coregulator, an essential component of the nucleosome remodeling and deacetylase (NuRD) complex, potentiates neuroprotective effects against ischemia/reperfusion (I/R) injury. But the underlying mechanism(s) remain largely unknown. Here, we discovered that neuronal MTA1 was a target of oxidative stress, and stimulation of neurons with oxygen glucose deprivation (OGD) treatment significantly inhibited MTA1 expression. Additionally, MTA1 depletion augmented ischemic oxidative stress and thus promoted oxidative stress-induced neuronal cell death by OGD. While studying the impact of MTA1 status on global neuronal gene expression, we unexpectedly discovered that MTA1 may modulate OGD-induced neuronal damage via regulation of distinct nitric oxide synthase (NOS) (namely neuronal NOS, nNOS) signaling. We provided in vitro evidence that NOS1 is a chromatin target of MTA1 in OGD-insulted neurons. Mechanistically, neuronal ischemia-mediated repression of NOS1 expression is accompanied by the enhanced recruitment of MTA1 along with histone deacetylases (HDACs) to the NOS1 promoter, which could be effectively blocked by a pharmacological inhibitor of the HDACs. These findings collectively reveal a previously unrecognized, critical homeostatic role of MTA1, both as a target and as a component of the neuronal oxidative stress, in the regulation of acute neuronal responses against brain I/R damage. Our study also provides a molecular mechanistic explanation for the previously reported neurovascular protection by selective nNOS inhibitors.

Enforced expression of hsa-miR-125a-3p in breast cancer cells potentiates docetaxel sensitivity via modulation of BRCA1 signaling

Epigenetic gene inactivation by microRNAs (miRNAs) plays a key role in malignant transformation, prevention of apoptosis, drug resistance and metastasis. It has been shown that miR-125a is down-regulated in HER2-amplified and HER2-overexpressing breast cancers (BCa), and this miRNA is believed to serve as an important tumor suppressor. miR-125a has two mature forms: hsa-miR-125a-3p and hsa-miR-125a-5p. However, the functional details of these miRNAs in BCa, particularly during pathogenesis of drug resistance, remain largely unexplored. Herein, we reported that hsa-miR-125a-3p expression was significantly reduced in chemoresistant BCa tissues and in experimentally established chemoresistant BCa cells. hsa-miR-125a-3p knockdown promoted cell proliferation and compromised docetaxel (Dox)-induced cell death, whereas overexpression of hsa-miR-125a-3p attenuated Dox chemoresistance in BCa cells. From a mechanistic standpoint, hsa-miR-125a-3p directly targeted 3'-untranslated regions (3'-UTRs) of breast cancer early onset gene 1 (BRCA1) and inhibits its protein expression via translational repression mechanism. In addition, suppression of BRCA1 expression by siRNA treatment effectively improved hsa-miR-125a-3p deficiency-triggered chemoresistance in BCa cells. Collectively, these findings suggest that hsa-miR-125a-3p may function as a tumor suppressor by regulating the BRCA1 signaling, and reintroduction of hsa-miR-125a-3p analogs could be a potential adjunct therapy for advanced/chemoresistant BCa.

Runs of homozygosity reveal signatures of positive selection for reproduction traits in breed and non-breed horses

Background

Modern horses represent heterogeneous populations specifically selected for appearance and performance. Genomic regions under high selective pressure show characteristic runs of homozygosity (ROH) which represent a low genetic diversity. This study aims at detecting the number and functional distribution of ROHs in different horse populations using next generation sequencing data.

Methods

Next generation sequencing was performed for two Sorraia, one Dülmen Horse, one Arabian, one Saxon-Thuringian Heavy Warmblood, one Thoroughbred and four Hanoverian. After quality control reads were mapped to the reference genome EquCab2.70. ROH detection was performed using PLINK, version 1.07 for a trimmed dataset with 11,325,777 SNPs and a mean read depth of 12. Stretches with homozygous genotypes of >40 kb as well as >400 kb were defined as ROHs. SNPs within consensus ROHs were tested for neutrality. Functional classification was done for genes annotated within ROHs using PANTHER gene list analysis and functional variants were tested for their distribution among breed or non-breed groups.

Results

ROH detection was performed using whole genome sequences of ten horses of six populations representing various breed types and non-breed horses. In total, an average number of 3492 ROHs were detected in windows of a minimum of 50 consecutive homozygous SNPs and an average number of 292 ROHs in windows of 500 consecutive homozygous SNPs. Functional analyses of private ROHs in each horse revealed a high frequency of genes affecting cellular, metabolic, developmental, immune system and reproduction processes. In non-breed horses, 198 ROHs in 50-SNP windows and seven ROHs in 500-SNP windows showed an enrichment of genes involved in reproduction, embryonic development, energy metabolism, muscle and cardiac development whereas all seven breed horses revealed only three common ROHs in 50-SNP windows harboring the fertility-related gene YES1. In the Hanoverian, a total of 18 private ROHs could be shown to be located in the region of genes potentially involved in neurologic control, signaling, glycogen balance and reproduction. Comparative analysis of homozygous stretches common in all ten horses displayed three ROHs which were all located in the region of KITLG, the ligand of KIT known to be involved in melanogenesis, haematopoiesis and gametogenesis.

Conclusions

The results of this study give a comprehensive insight into the frequency and number of ROHs in various horses and their potential influence on population diversity and selection pressures. Comparisons of breed and non-breed horses suggest a significant artificial as well as natural selection pressure on reproduction performance in all types of horse populations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1977-3) contains supplementary material, which is available to authorized users.

The proteasome inhibitor bortezomib induces testicular toxicity by upregulation of oxidative stress, AMP-activated protein kinase (AMPK) activation and deregulation of germ cell development in adult murine testis

Understanding how chemotherapeutic agents mediate testicular toxicity is crucial in light of compelling evidence that male infertility, one of the severe late side effects of intensive cancer treatment, occurs more often than they are expected to. Previous study demonstrated that bortezomib (BTZ), a 26S proteasome inhibitor used to treat refractory multiple myeloma (MM), exerts deleterious impacts on spermatogenesis in pubertal mice via unknown mechanisms. Here, we showed that intermittent treatment with BTZ resulted in fertility impairment in adult mice, evidenced by testicular atrophy, desquamation of immature germ cells and reduced caudal sperm storage. These deleterious effects may originate from the elevated apoptosis in distinct germ cells during the acute phase and the subsequent disruption of Sertoli-germ cell anchoring junctions (AJs) during the late recovery. Mechanistically, balance between AMP-activated protein kinase (AMPK) activation and Akt/ERK pathway appeared to be indispensable for AJ integrity during the late testicular recovery. Of particular interest, the upregulated testicular apoptosis and the following disturbance of Sertoli-germ cell interaction may both stem from the excessive oxidative stress elicited by BTZ exposure. We also provided the in vitro evidence that AMPK-dependent mechanisms counteract follicle-stimulating hormone (FSH) proliferative effects in BTZ-exposed Sertoli cells. Collectively, BTZ appeared to efficiently prevent germ cells from normal development via multiple mechanisms in adult mice. Employment of antioxidants and/or AMPK inhibitor may represent an attractive strategy of fertility preservation in male MM patients exposed to conventional BTZ therapy and warrants further investigation.

MTA1--a stress response protein: a master regulator of gene expression and cancer cell behavior

Gene mutation's role in initiating carcinogenesis has been controversial, but it is consensually accepted that both carcinogenesis and cancer metastasis are gene-regulated processes. MTA1, a metastasis-associated protein, has been extensively researched, especially regarding its role in cancer metastasis. In this review, I try to elucidate MTA1's role in both carcinogenesis and metastasis from a different angle. I propose that MTA1 is a stress response protein that is upregulated in various stress-related situations such as heat shock, hypoxia, and ironic radiation. Cancer cells are mostly living in a stressful environment of hypoxia, lack of nutrition, and immune reaction attacks. To cope with all these stresses, MTA1 expression is upregulated, plays a role of master regulator of gene expression, and helps cancer cells to survive and migrate out of their original dwelling.

Upregulation and nuclear translocation of testicular ghrelin protects differentiating spermatogonia from ionizing radiation injury

Proper control of apoptotic signaling is important for maintenance of testicular homeostasis after ionizing radiation (IR). Herein, we challenged the hypothesis that ghrelin, a pleiotropic modulator, is potentially involved in IR-induced germ cell injury. Lower body exposure to 2 Gy of IR induced a notable increase of ghrelin expression in the nuclear of differentiating spermatogonia at defined stages, with an impairment in the Leydig cells (LCs)-expressing ghrelin. Unexpectedly, inhibition of the ghrelin pathway by intraperitoneal injection of a specific GHS-R1α antagonist enhanced spermatogonia elimination by apoptosis during the early recovery following IR, and thereafter resulted in impaired male fertility, suggesting that the anti-apoptotic effects of evoked ghrelin, although transient along testicular IR injury, have a profound influence on the post-injury recovery. In addition, inhibition of ghrelin signaling resulted in a significant increase in the intratesticular testosterone (T) level at the end of 21 days after IR, which should stimulate the spermatogenic recovery from surviving spermatogonia to a certain extent during the late stage. We further demonstrated that the upregulation and nuclear trafficking of ghrelin, elaborately regulated by IR-elicited antioxidant system in spermatogonia, may act through a p53-dependent mechanism. The elicitation of ghrelin expression by IR stress, the regulation of ghrelin expression by IR-induced oxidative stress and the interaction between p53 and ghrelin signaling during IR injury were confirmed in cultured spermatogonia. Hence, our results represent the first evidence in support of a radioprotective role of ghrelin in the differentiating spermatogonia. The acutely, delicate regulation of local-produced ghrelin appears to be a fine-tune mechanism modulating the balance between testicular homeostasis and early IR injury.

Elicitation of metastasis associated protein 2 expression in the phagocytosis by murine testicular Sertoli cells

Efficient phagocytic clearance of apoptotic spermatogenic cells and residual bodies (RBs) by Sertoli cells (SCs) is crucial for functional mature spermatogenesis. However, little is known about the molecular mechanisms underlying this SCs function. Herein, we reported for the first time that SCs-expressing metastasis associated protein 2 (Mta2), a chromatin modifier playing a critical role in modifying DNA accessibility for transcriptional regulation, was steadily up-regulated when SCs were co-cultured with RBs. The most efficient stimulatory substrates for the inducement of phagocytosis-elicited Mta2 expression were RBs and fragments from apoptotic spermatocytes. Furthermore, one major result of this response is the transcriptional repression of follicle-stimulating hormone receptor gene (Fshr) expression during phagocytosis, which should lead to a low level of circulated FSH because effects of FSH on spermatogenesis is fundamentally regulated by the down-regulation of Fshr after exposure to FSH. Given that high concentration of circulated FSH inhibits SCs phagocytic activity and impairment of MTA2 expression is associated with the abnormal high level of serum FSH, our present results suggest that the FSH/MTA2/Fshr cascade may serve as an indispensable negative feedback mechanism to help to maintain low level of circulated FSH, which is required for the normal occurrence of SCs phagocytosis.