Heat stress–induced autophagy promotes lactate secretion in cultured immature boar Sertoli cells by inhibiting apoptosis and driving SLC2A3 , LDHA , and SLC16A1 expression

Joint Analysis of Genome-wide DNA Methylation and Transcription Sequencing Identifies the Role of BAX Gene in Heat Stress-Induced-Sertoli Cells Apoptosis

The problem of male infertility is a global health crisis and poses a serious threat to the well-being of families. Under heat stress (HS), the reduction of Sertoli cells (SCs) inhibits energy transport and nutrient supply to germ cells, leading to spermatogenesis failure. DNA methylation of genes is a central epigenetic regulatory mechanism in mammalian reproduction. However, it remains unclear how DNA methylation regulates gene expression in heat-stressed SCs. In this study, we investigated whether the decrease in SC levels during HS could be related to epigenetic DNA modifications. The cells exposed to HS showed changes in differential methylation cytosines and regions (DMCs/DMRs) and differential expression genes (DEGs), but not in global DNA methylations. One of the most important biological processes affected by HS is cell apoptosis induced by the intrinsic apoptotic signaling pathway (GO: 2,001,244, P < 0.05) by enrichment in the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The joint analysis showed that several gene expressions in RNA-seq and WGBS overlapped and the shortlisted genes BAX, HSPH1, HSF1B, and BAG were strongly correlated with stress response and apoptosis. Methylation-specific PCR (MSP) and flow cytometry (FCM) analyzes showed that reduced promoter methylation and enhanced gene expression of BAX with a consequence of apoptosis. The activity of BAX, as well as an increase in its expression, is likely to result in a reduction of SCs population which could further impair ATP supply and adversely affect membrane integrity. These findings provide novel insights into the molecular mechanisms through which stressors cause male reproductive dysfunction and a new molecular etiology of male infertility.

Emerging Role of Autophagy in Governing Cellular Dormancy, Metabolic Functions, and Therapeutic Responses of Cancer Stem Cells

Tumors are composed of heterogeneous populations of dysregulated cells that grow in specialized niches that support their growth and maintain their properties. Tumor heterogeneity and metastasis are among the major hindrances that exist while treating cancer patients, leading to poor clinical outcomes. Although the factors that determine tumor complexity remain largely unknown, several genotypic and phenotypic changes, including DNA mutations and metabolic reprograming provide cancer cells with a survival advantage over host cells and resistance to therapeutics. Furthermore, the presence of a specific population of cells within the tumor mass, commonly known as cancer stem cells (CSCs), is thought to initiate tumor formation, maintenance, resistance, and recurrence. Therefore, these CSCs have been investigated in detail recently as potential targets to treat cancer and prevent recurrence. Understanding the molecular mechanisms involved in CSC proliferation, self-renewal, and dormancy may provide important clues for developing effective therapeutic strategies. Autophagy, a catabolic process, has long been recognized to regulate various physiological and pathological processes. In addition to regulating cancer cells, recent studies have identified a critical role for autophagy in regulating CSC functions. Autophagy is activated under various adverse conditions and promotes cellular maintenance, survival, and even cell death. Thus, it is intriguing to address whether autophagy promotes or inhibits CSC functions and whether autophagy modulation can be used to regulate CSC functions, either alone or in combination. This review describes the roles of autophagy in the regulation of metabolic functions, proliferation and quiescence of CSCs, and its role during therapeutic stress. The review further highlights the autophagy-associated pathways that could be used to regulate CSCs. Overall, the present review will help to rationalize various translational approaches that involve autophagy-mediated modulation of CSCs in controlling cancer progression, metastasis, and recurrence.

Autophagy, a critical element in the aging male reproductive disorders and prostate cancer: a therapeutic point of view

Autophagy is a highly conserved, lysosome-dependent biological mechanism involved in the degradation and recycling of cellular components. There is growing evidence that autophagy is related to male reproductive biology, particularly spermatogenic and endocrinologic processes closely associated with male sexual and reproductive health. In recent decades, problems such as decreasing sperm count, erectile dysfunction, and infertility have worsened. In addition, reproductive health is closely related to overall health and comorbidity in aging men. In this review, we will outline the role of autophagy as a new player in aging male reproductive dysfunction and prostate cancer. We first provide an overview of the mechanisms of autophagy and its role in regulating male reproductive cells. We then focus on the link between autophagy and aging-related diseases. This is followed by a discussion of therapeutic strategies targeting autophagy before we end with limitations of current studies and suggestions for future developments in the field.

BMAL1 involved in autophagy and injury of thoracic aortic endothelial cells of rats induced by intermittent heat stress through the AMPK/mTOR/ULK1 pathway

Physiological activities of the body exhibit an obvious biological rhythm. At the core of the circadian rhythm, BMAL1 is the only clock gene whose deletion leads to abnormal physiological functions. However, whether intermittent heat stress influences cardiovascular function by altering the circadian rhythm of clock genes has not been reported. This study aimed to investigate whether intermittent heat stress induces autophagy and apoptosis, and the effects of BMAL1 on thoracic aortic autophagy and apoptosis. An intermittent heat stress model was established in vitro, and western blotting and immunofluorescence were used to detect the expression of autophagy, apoptosis, the AMPK/mTOR/ULK1 pathway, and BMAL1. After BMAL1 silencing, RT-qPCR was performed to detect the expression levels of autophagy and apoptosis-related genes. Our results suggest that heat stress induces autophagy and apoptosis in RTAECs. In addition, intermittent heat stress increased the phosphorylation of AMPK and ULK1, but reduced the phosphorylation of mTOR, AMPK inhibitor Compound C reversed the phosphorylation of AMPK, mTOR, and ULK1, and Beclin1 and LC3-II/LC3-I were downregulated. Furthermore, BMAL1 expression was elevated in vitro and shBMAL1 decreased autophagy and apoptosis. We revealed that intermittent heat stress induces autophagy and apoptosis, and that BMAL1 may be involved in the occurrence of autophagy and apoptosis.

Thermoregulation mechanisms and perspectives for validating thermal windows in pigs with hypothermia and hyperthermia: An overview

Specific anatomical characteristics make the porcine species especially sensitive to extreme temperature changes, predisposing them to pathologies and even death due to thermal stress. Interest in improving animal welfare and porcine productivity has led to the development of various lines of research that seek to understand the effect of certain environmental conditions on productivity and the impact of implementing strategies designed to mitigate adverse effects. The non-invasive infrared thermography technique is one of the tools most widely used to carry out these studies, based on detecting changes in microcirculation. However, evaluations using this tool require reliable thermal windows; this can be challenging because several factors can affect the sensitivity and specificity of the regions selected. This review discusses the thermal windows used with domestic pigs and the association of thermal changes in these regions with the thermoregulatory capacity of piglets and hogs.

Transcriptome Profiling in Swine Macrophages Infected with African Swine Fever Virus (ASFV) Uncovers the Complex and Close Relationship with Host

African swine fever virus (ASFV) is a pathogen to cause devastating and economically significant diseases in domestic and feral swine. ASFV mainly infects macrophages and monocytes and regulates its replication process by affecting the content of cytokines in the infected cells. There is a limited understanding of host gene expression and differential profiles before and after ASFV infection in susceptible cells. In this study, RNA-seq technology was used to analyze the transcriptomic change in PAMs infected with ASFV at different time points (0 h, 12 h, 24 h). As a result, a total of 2748, 1570, and 560 genes were enriched in group V12 h vs. MOCK, V24 h vs. MOCK, and V24 h vs. V12 h, respectively. These DEGs (differentially expressed genes) in each group were mainly concentrated in the KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways related to innate immunization and inflammation, including the NF-κB signaling pathway, Toll-like receptor signaling pathway, TNF signaling pathway, IL-17 signaling pathway, cytokine-cytokine receptor interaction, and chemokine signaling pathway. Furthermore, the increased levels of IL-1β, TNF-α, IKKβ, CXCL2, and TRAF2 and decreased level of IκBα were validated through the qPCR method. These results suggested that ASFV infection can activate the NF-κB signaling pathway in the early stage. In general, this study provides a theoretical basis for further understanding the pathogenesis and immune escape mechanism of ASFV.

Melatonin alleviates the heat stress-induced impairment of Sertoli cells by reprogramming glucose metabolism

Sertoli cells (SCs) provide structural and nutritional support for developing germ cells. Normal glucose metabolism of SCs is necessary for spermatogenesis. Melatonin could alleviate the effects of heat stress on spermatogenesis. However, the influences of heat stress on glucose metabolism in SCs remain unclear, and the potential protective mechanisms of melatonin on SCs need more exploration. In this study, boar SCs were treated at 43°C for 30 min, and different concentrations of melatonin were added to protect SCs from heat stress-induced impairment. These results showed that heat stress-induced oxidative stress caused cell apoptosis, inhibited the pentose phosphate pathway, and decreased the ATP content. Furthermore, heat stress increased the expressions of glucose intake- and glycolytic-related enzymes, which enhanced the glycolysis activity to compensate for the energy deficit. Melatonin relieved heat stress-induced oxidative stress and apoptosis by activating the Kelch-like ECH-associated protein 1 (KEAP1)/NF-E2-related factor 2 signaling pathway to increase the capacity of antioxidants. In addition, melatonin enhanced heat-shock protein 90 (HSP90) expression through melatonin receptor 1B (MTNR1B), thereby stabilizing hypoxia-inducible factor-1α (HIF-1α). Activation of the HIF-1α signaling pathway enhanced glycolysis, promoted the pentose phosphate pathway, and increased cell viability. Our results suggest that melatonin reprograms glucose metabolism in SCs through the MTNR1B-HSP90-HIF-1α axis and provides a theoretical basis for preventing heat stress injury.

Whole Genome Analyses Reveal Novel Genes Associated with Chicken Adaptation to Tropical and Frigid Environments

INTRODUCTION

Investigating the genetic footprints of historical temperature selection can get insights to the local adaptation and feasible influences of climate change on long-term population dynamics.

OBJECT

Chicken is a significative species to study genetic adaptation on account of its similar domestication track related to human activity with the most diversified varieties. Yet, few studies have demonstrated the genetic signatures of its adaptation to naturally tropical and frigid environments.

METHOD

Here, we generated whole genome resequencing of 119 domesticated chickens in China including the following breeds which are in order of breeding environmental temperature from more tropical to more frigid: Wenchang chicken (WCC), green-shell chicken (GSC), Tibetan chicken (TBC), and Lindian chicken (LDC).

RESULTS

Our results showed WCC branched off earlier than LDC with an evident genetic admixture between WCC and LDC, suggesting their closer genetic relationship. Further comparative genomic analyses solute carrier family 33 member 1 (SLC33A1) and thyroid stimulating hormone receptor (TSHR) genes exhibited stronger signatures for positive selection in the genome of the more tropical WCC. Furthermore, genotype data from about 3,000 African local ecotypes confirmed that allele frequencies of single nucleotide polymorphisms (SNPs) in these 2 genes appeared strongly associated with tropical environment adaptation. In addition, the NADH:ubiquinone oxidoreductase subunit S4 (NDUFS4) gene exhibited a strong signature for positive selection in the LDC genome, and SNPs with marked allele frequency differences indicated a significant relationship with frigid environment adaptation.

CONCLUSION

Our findings partially clarify how selection footprints from environmental temperature stress can lead to advantageous genomic adaptions to tropical and frigid environments in poultry and provide a valuable resource for selective breeding of chickens.

Heat treatment reduced the expression of miR-7-5p to facilitate insulin-stimulated lactate secretion by targeting IRS2 in boar Sertoli cells

Insulin dysfunction of diabetes mellitus (DM) disorders the glucose metabolism in Sertoli cells (SCs), resulting in the impairment of spermatogenesis.Insulin signaling system in Sertoli cells (SCs) plays an important role in regulating lactate secretion. Heat treatment could increase the lactate secretion of boar SCs, but whether heat treatment participates in lactate secretion by improving the sensitivity of insulin is unknown. In the current study, the primary SCs from 21-day-old boar were employed to treat with 100 nM insulin for 24 h or heat treatment (43 °C, 30 min). Heat treatment strengthened the effect of insulin on the effect of lactate secretion. In addition, heat treatment increased the expression of insulin-induced insulin receptor substrate 2 (IRS2), but reduced the expression of miR-7-5p. Using dual luciferase reporter assay and Western blot, the study found that IRS2 is a potential target gene of miR-7-5p. Heat treatment also enhanced the Phosphorylation of insulin-stimulated PI3K/Akt, and increased lactate secretion by promoting the expression of Glucose Transporter 3 (GLUT3), Lactate Dehydrogenase-A (LDHA) and monocarboxylate transporter 1 (MCT1). Furthermore, miR-7-5p inhibitor could partly mimic the effects of heat treatment on lactate production of SCs, indicating that heat treatment improves insulin sensitivity by regulating the expression of miR-7-5p/IRS2/PI3K/Akt. These results reveal a novel miRNA-mediated mechanism of heat treatment on the regulation of lactate metabolism production, and suggest that targeting miR-7-5p is a probably therapeutic method to insulin dysfunction-induced metabolic diseases.

PGAM1 regulates the glycolytic metabolism of SCs in tibetan sheep and its influence on the development of SCs

This study was to explore the regulation effect of PGAM1 on the proliferation, apoptosis and glycolysis pathway of Tibetan sheep Sertoli cells. In this paper, the reproductive organs of male Tibetan sheep before pre-puberty (3 months old), sexual maturity (1 year old) and adult (3 years old) were used as experimental materials. The complete CDS region sequence of PGAM1 gene was cloned for bioinformatics analysis, and had the closest relationship with Tibetan antelope. QRT-PCR, Western blot and immunohistochemical staining were used to detect the expression and localization of PGAM1 in the testis and epididymis tissues of Tibetan sheep at different growth and development stages at the transcription and translation levels. Then the Tibetan sheep primary Sertoli cells (SCs) were isolated to construct PGAM1 gene overexpression and interference vectors, and to transfect primary SCs so as to promote and inhibit PGAM1 gene expression; CCK-8 and flow cytometry were used to detect the proliferation effect of SCs;qRT-PCR technology was employed to detect the changes in the expression of genes related to cell proliferation and apoptosis. Different kits were used to detect pyruvate, lactic acid, ATP production and LDH activity during glycolysis, and to detect the changes in the expression of downstream genes in the glycolysis pathway. The results showed that the CDS region of Tibetan sheep PGAM1 gene was 765 bp in length, which can encode 254 amino acids; and the expression of PGAM1 protein in the testis and epididymis increased at 1Y group and 3Ygroup compared with 3 M group, and that the PGAM1 protein mainly existed in SCs and Leydig cells at different developmental stages. CCK-8 and flow cytometry test results found that compared with the empty vector group (pcDNA3.1(+)), the proliferation rate of the PGAM1 gene overexpression group (pcDNA3.1(+)-PGAM1) decreased. The mRNA expression of the cell proliferation related genes PCNA and Bcl2 was significantly decreased (P < 0.05), and the expression of apoptosis-related genes Bax and caspase3 was significantly increased (P < 0.05). The expression of downstream genes in the glycolysis pathway was significant increased (P < 0.05), pyruvate content, ATP content, lactic acid production and LDH activity increased significantly (P < 0.05). Compared with the interference control group (NC), the proliferation rate of the PGAM1 gene interference group (si-PGAM1) was weakened. The mRNA expression of the cell proliferation-related genes PCNA and Bcl2 was significantly increased (P < 0.05), and the expression of cell apoptosis related genes Bax and caspase3 was significantly decreased (P < 0.05). The expression of downstream genes in the glycolysis pathway was significantly reduced (P < 0.05), and the pyruvate content, ATP content, lactic acid production and LDH activity were significantly decreased (P < 0.05). The PGAM1 gene might regulate the glycolytic metabolism pathway and regulate the sperm formation and maturation process by affecting the proliferation and apoptosis of SCs. This result provides basic data for the study of the function of PGAM1 in sheep testicular development.

Acute heat stress reduces viability but increases lactate secretion of porcine immature Sertoli cells through transcriptome reprogramming

Sertoli cells, important constituents of the somatic niche, supports the growth and development of spermatogonia. Heat stress (HS), among multiple intrinsic and external factors, can induce physiological and biochemical changes in Sertoli cells. However, the underlying molecular mechanism remains largely unclear. Here, we showed that acute heat stress (43 °C, 0.5 h) could reduce cell viability, promote apoptosis, and increase the lactate production of porcine immature Sertoli cells (iSCs) cultured in vitro. Then, transcriptome sequencing identified 126 immediately and 3372 prolonged responded differentially expressed genes (DEGs) after acute heat stress (43 °C, 0.5 h) (HS0.5), and 36 h recovery culture following heat stress (HS0.5-R36), respectively. Enrichment analyses found different signaling pathways: immediate changes including cell response to heat, regulation of cellular response to stress, heat shock protein binding, chaperon-mediated protein folding, and sterol biosynthetic process, but prolonged changes mainly involving cell cycle, regulation of apoptotic process/cell proliferation, reproductive process, P53, PI3K-Akt and Glycolysis/Gluconeogenesis. Furthermore, transcriptional patterns of 9 DEGs (Dnajb1, Traf6, Insig1, Gadd45g, Hdac6, Fkbp4, Serpine1, Pfkp and Galm), and 6 heat shock proteins (HSPs) (Hspa6, Hspb1, Hspd1, HSP90aa1, HSP90ab1 and Hsph1) were validated, as well as the protein pattern of HSP90AA1 via immunostaining and western blot. Taken together, heat stress could initiate immediate changes of heat shock-related genes, and reprogram transcriptome and signaling pathways affecting the viability, apoptosis and metabolite production of pig iSCs.

Inhibition of p97/VCP function leads to defective autophagosome maturation, cell cycle arrest and apoptosis in mouse Sertoli cells

p97/valosin-containing protein (VCP) is expressed in many cells and plays critical functions in a broad range of diverse cellular processes. Because it is expressed in the mouse testes, predominantly in Sertoli cells, and is known to play a critical role in autophagy and apoptosis in different cell types, we set out to investigate its function in autophagosome maturation, apoptosis and cell cycle arrest in a mouse Sertoli cell line. To study the mechanism of p97/VCP action, p97/VCP siRNA and a specific p97/VCP inhibitor, N²,N⁴-dibenzylquinazoline-2,4-diamine (DBeQ), were used in the mouse 15P1 Sertoli cell line. Loss of p97/VCP activity due to DBeQ exposure and silencing of p97/VCP (siVCP) expression results in autophagosome (LC3 and p62) accumulation in the cytoplasm of Sertoli cells. The coexpression of autophagosomal and lysosomal markers (LAMP1 and LAMP2) was reduced in cells in which p97/VCP expression had been inactivated. To better understand in which step of autophagy p97/VCP functions, the interaction between autophagosomal and autolysosomal markers was studied by coimmunoprecipitation and colocalization experiments. The interaction between autophagosomal markers and lysosomal markers decreased in siVCP-expressing and DBeQ-exposed cells. Moreover, the expression of siVCP and DBeQ exposure caused cytoplasmic vacuolation, induced caspase 3-7-mediated cell death and decreased cell cycle progression in mouse Sertoli cells. Taken together, the results show that p97/VCP is essential for autophagosome maturation and cell survival in mouse Sertoli cells. When these functions are prevented, impaired autophagy and apoptosis may have a detrimental effect on germ cells and cause male infertility.

Profiling of miRNAs in porcine Sertoli cells

Background

Sertoli cells (SCs) create a specialized environment to support and dictate spermatogenesis. MicroRNAs (miRNAs), a kind of ~ 22 nt small noncoding RNAs, have been reported to be highly abundant in mouse SCs and play critical roles in spermatogenesis. However, the miRNAs of porcine SCs remain largely unknown.

Methods

We isolated porcine SCs and conducted small RNA sequencing. By comparing miRNAs in germ cells, we systematically analyzed the miRNA expression pattern of porcine SCs. We screened the highly enriched SC miRNAs and predicted their functions by Gene Ontology analysis. The dual luciferase assay was used to elucidate the regulation of tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3) by ssc-miR-149.

Results

The analysis showed that 18 miRNAs were highly expressed in SCs and 15 miRNAs were highly expressed in germ cells. These miRNAs were predicted to mediate SC and germ cell functions. In addition, ssc-miR-149 played critical roles in SCs by targeting TRAF3.

Conclusion

Our findings provide novel insights into the miRNA expression pattern and their regulatory roles of porcine SCs.

Glucose Metabolism and Dynamics of Facilitative Glucose Transporters (GLUTs) under the Influence of Heat Stress in Dairy Cattle

Heat stress is one of the main threats to dairy cow production; in order to resist heat stress, the animal exhibits a variety of physiological and hormonal responses driven by complex molecular mechanisms. Heat-stressed cows have high insulin activity, decreased non-esterified fatty acids, and increased glucose disposal. Glucose, as one of the important biochemical components of the energetic metabolism, is affected at multiple levels by the reciprocal changes in hormonal secretion and adipose metabolism under the influence of heat stress in dairy cattle. Therefore, alterations in glucose metabolism have negative consequences for the animal’s health, production, and reproduction under heat stress. Lactose is a major sugar of milk which is affected by the reshuffle of the whole-body energetic metabolism during heat stress, contributing towards milk production losses. Glucose homeostasis is maintained in the body by one of the glucose transporters’ family called facilitative glucose transporters (GLUTs encoded by SLC2A genes). Besides the glucose level, the GLUTs expression level is also significantly changed under the influence of heat stress. This review aims to describe the effect of heat stress on systemic glucose metabolism, facilitative glucose transporters, and its consequences on health and milk production.

A Key Role of DNA Damage-Inducible Transcript 4 (DDIT4) Connects Autophagy and GLUT3-Mediated Stemness To Desensitize Temozolomide Efficacy in Glioblastomas

DNA damage-inducible transcript 4 (DDIT4) is known to participate in various cancers, including glioblastoma multiforme (GBM). However, contradictory roles of DDIT4 exist in inducing cell death and possessing anti-apoptotic functions against cancer progression. Herein, we investigated DDIT4 signaling in GBM and temozolomide (TMZ) drug resistance. We identified that TMZ induced DDIT4 upregulation, leading to desensitization against TMZ cytotoxicity in GBM cells. Higher DDIT4 levels were found in glioma cells and mesenchymal-type GBM patients, and these higher levels were positively correlated with mesenchymal markers. Furthermore, patients with lower DDIT4 levels, especially O-6-methylguanine-DNA methyltransferase (MGMT)-methylated patients, exhibited better TMZ therapeutic efficacy. We determined that higher levels of 5 DDIT4-associated downstream genes, including SLC2A3 (also known as glucose transporter 3 (GLUT3)), can be used to predict a poor prognosis. Among these 5 genes, only GLUT3 was upregulated in both TMZ-treated and DDIT4-overexpressing cells. DDIT4-mediated GLUT3 expression was also identified, and its expression decreased TMZ's cytotoxicity. A significant correlation existed between DDIT4 and GLUT3. DDIT4 signaling was found to be involved in both glycolytic and autophagic pathways. However, GLUT3 only participated in the exhibition of DDIT4-mediated stemness, resulting from glycolytic regulation, but not in DDIT4-mediated autophagic signaling. Finally, we identified TMZ-upregulated activating transcription factor 4 (ATF4) as an upstream regulator of DDIT4-mediated GLUT3/stemness signaling and autophagy. Consequently, ATF4/DDIT4 signaling was connected to both autophagy and GLUT3-regulated stemness, which are involved in TMZ drug resistance and the poor prognoses of GBM patients. Targeting DDIT4/GLUT3 signaling might be a new direction for glioma therapy.

Tissue-specific effects of temperature on proteasome function

Variation in ambient growth temperature can cause changes in normal animal physiology and cellular functions such as control of protein homeostasis. A key mechanism for maintaining proteostasis is the selective degradation of polyubiquitinated proteins, mediated by the ubiquitin-proteasome system (UPS). It is still largely unsolved how temperature changes affect the UPS at the organismal level. Caenorhabditis elegans nematodes are normally bred at 20 °C, but for some experimental conditions, 25 °C is often used. We studied the effect of 25 °C on C. elegans UPS by measuring proteasome activity and polyubiquitinated proteins both in vitro in whole animal lysates and in vivo in tissue-specific transgenic reporter strains. Our results show that an ambient temperature shift from 20 to 25 °C increases the UPS activity in the intestine, but not in the body wall muscle tissue, where a concomitant accumulation of polyubiquitinated proteins occurs. These changes in the UPS activity and levels of polyubiquitinated proteins were not detectable in whole animal lysates. The exposure of transgenic animals to 25 °C also induced ER stress reporter fluorescence, but not the fluorescence of a heat shock responsive reporter, albeit detection of a mild induction in hsp-16.2 mRNA levels. In conclusion, C. elegans exhibits tissue-specific responses of the UPS as an organismal strategy to cope with a rise in ambient temperature.

Inactivation of glycogen synthase kinase-3α is required for mitochondria-mediated apoptotic germ cell phagocytosis in Sertoli cells

The rapid and efficient clearance of apoptotic germ cells (GCs) by Sertoli cells (SCs) is important for spermatogenesis. High mitochondrial activity in phagocytes is critical for continued clearance of apoptotic cells. However, the underlying molecular mechanism is poorly understood. Glycogen synthase kinase-3α (GSK3α) is a protein kinase that participates in the regulation of mitochondrial activity. Immunohistochemistry evidenced the predominant presence of the Ser21 phosphorylation GSK3α (inactivation) signal in SCs. Heat shock-induced apoptosis of GCs and dephosphorylation of GSK3α in SCs is a perfect model to investigate the role of GSK3α in phagocytic action. The number of apoptotic GCs was significantly lower in GSK3α inhibitor pre-treated mice with HS compared to normal control. In vitro phagocytosis assays shown that the phagocytic activity in GSK3α activated SCs was downregulated, while GSK3α inhibitor supplementation restored this process. Moreover, GSK3α activation participates in the alteration of the mitochondrial ultrastructure and activity. In particular, GSK3α activation inhibits mitochondrial fission via phosphorylation of dynamin related protein 1 at Ser637. Changes of mitochondrial activity resulted in the accumulation of lipid droplets and the alteration of metabolism pattern in SCs. In summary, our results demonstrate that inactivation of GSK3α is required for mitochondria-mediated apoptotic GCs phagocytosis in SCs.

Autophagy as a consequence of seasonal functions of testis and epididymis in adult male European bison (Bison bonasus, Linnaeus 1758)

The European bison is still an animal endangered with extinction, so by learning factors that regulate its reproduction, we can contribute to the survival of this species. On the other hand, autophagy is a dynamic, lisosomal, and evolutionary conserved process which is essential for animal cell survival, homeostasis, and differentiation. This process was demonstrated in many species and in many organs; however, information on the metabolic course of autophagy in the male reproductive system in seasonally reproducing species is lacking. Therefore, in this study, we examined for the first time several autophagy-related factors (mTOR, ULK1, Atg13, PI3K, beclin1, beclin2, Atg14, Atg5, Atg16L, LC3) in testicular and epididymal tissues obtained from adult male individuals of the European bison. We compared the level of gene expression, protein synthesis, and localization of autophagy-related factors between June, September, and December (before, during, and after reproductive activity, respectively). We confirmed that the induction of autophagy was at the highest level in the period after reproductive activity, i.e., in December, when a significant increase in the gene and protein expression was observed for the majority of these factors, probably to ensure cellular protection. However, autophagy was also clearly marked in September, during the intense spermatogenesis, and this may indicate a great demand for autophagy-related proteins required for the normal development of reproductive cells. Obtained results seem to confirm that autophagy pathway, as a consequence of seasonal reproduction, may control the normal course of spermatogenesis in the male European bison.

Co-enzyme Q10 protects primary chicken myocardial cells from heat stress by upregulating autophagy and suppressing the PI3K/AKT/mTOR pathway

In this study, we investigated the function of co-enzyme Q10 (Q10) in autophagy of primary chicken myocardial cells during heat stress. Cells were treated with Q10 (1 μΜ, 10 μΜ, and 20 μM) before exposure to heat stress. Pretreatment of chicken myocardial cells with Q10 suppressed the decline in cell viability during heat stress and suppressed the increase in apoptosis during heat stress. Treatment with 20 μM Q10 upregulated autophagy-associated genes during heat stress. The expression of LC3-II was highest in cells treated with 20 μM Q10. Pretreatment with Q10 decreased reactive oxygen species (ROS) levels during heat stress. The number of autophagosomes was significantly increased by 20 μM Q10 treatment, as demonstrated by electron microscopy or monodansylcadaverine (MDC) fluorescence. SQSTM1 accumulation was diminished by Q10 treatment during heat stress, and the number of LC3II puncta was increased. Treatment with 20 μM Q10 also decreased the activation of the PI3K/Akt/mTOR pathway. Our results showed that co-enzyme Q10 can protect primary chicken myocardial cells by upregulating autophagy and suppressing the PI3K/Akt/mTOR pathway during heat stress.

Glioblastoma: Targeting the autophagy in tumorigenesis

Glioblastoma (GBM) is one of the most malignant and aggressive primary brain tumor, with a mean life expectancy of less than 15 months. The malignant nature of GBM prompts the need for further research on its tumorigenesis and novel treatments to improve its outcome. One of the promising research targets is autophagy, a fundamental metabolic process of degrading and recycling cellular components. Interventions to activate or inhibit autophagy have both been proposed as GBM therapies, suggesting a controversial, context-dependent role of autophagy in GBM tumorigenesis. In this review, we highlight the molecular links between GBM and autophagy with the focus on the effects of autophagy on the stemness maintenance, metabolism and proteostasis in GBM tumorigenesis. Understanding the molecular pathways involved in autophagy target is critical for GBM therapy.

Oxidative stress mediates heat-induced changes of tight junction proteins in porcine sertoli cells via inhibiting CaMKKβ-AMPK pathway

Heat stress causes reversible changes in tight junction proteins in immature Sertoli cells via inhibition of the AMPK signaling pathway; these effects are accompanied by an increase in the early apoptotic rate and decrease in the cell viability of Sertoli cells. Since heat stress is known to also cause oxidative damage, in the present study, we investigated whether the earlier mentioned effects of heat stress were brought about via the induction of oxidative stress in boar Sertoli cells. Immature Sertoli cells obtained from 3-week-old piglets were subjected to heat treatment (43 °C, 30 min), and the percentage of ROS-positive cells, the malonaldehyde (MDA) concentration, and the activity of the antioxidases, including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were measured. Next, the Sertoli cells were treated with N-acetyl-l-cysteine (NAC) (1 mmol/L, 2 h), an antioxidant agent, before they were exposed to heat stress. The effects of NAC on ROS accumulation, MDA levels, antioxidase activity, the CaMKKβ-AMPK signaling pathway and expression of tight junction proteins were assessed. The results showed that heat stress reversibly increased the percentage of ROS-positive cells and MDA levels, and decreased the activity of SOD, GSH-Px, and CAT. Pretreatment with NAC abrogated these effects of heat stress. Additionally, NAC reversed the heat stress-induced decrease in the expression of CaMKKβ and dephosphorylation of AMPK. NAC also obviously rescued the heat stress-induced downregulation of tight junction proteins (claudin-11, JAM-A, occludin, and ZO-1) both at the mRNA and protein level. In conclusion, the findings indicate that oxidative damage participates in heat stress-induced downregulation of tight junction proteins in Sertoli cells by inhibiting the CaMKKβ-AMPK axis. Further, NAC reversed the effects of heat stress on tight junction proteins; this means that it has potential as a protective agent that can prevent reproductive dysfunction in boars under conditions of heat stress.

Pig SOX9: Expression profiles of Sertoli cell (SCs) and a functional 18 bp indel affecting testis weight

Sex determining region Y-box 9 (SOX9), an important member of the SRY- type HMGbox (SOX) gene family, plays an important role in the regulation of mammalian reproduction, including sex differentiation during the embryonic development stage and spermatogenesis after birth. To explore the roles of polymorphism and expression of the SOX9 gene in the development of testes, we analyzed the indel of SOX9 in pigs and the corresponding expression level of the SOX9 gene in 7-day and 5-month-old porcine Sertoli cells. Results revealed that the DD haplotype of SOX9 gene as well as the ID genotype were significantly associated with larger testicular weight, while the II haplotype was closely related to the smaller testicular weight. More importantly, the SOX9 gene expression of ID genotyped group was significantly higher than that in II genotyped group. Our results first revealed that the indel polymorphism and expression of SOX9 were significantly associated with pig reproduction traits indicating the critical roles of SOX9 gene in testes development. The study provides a new clue for understanding the regulation of animal reproductive activities.

Heat exposure affected the reproductive performance of pregnant mice: Enhancement of autophagy and alteration of subcellular structure in the corpus luteum

To investigate whether autophagy and subcellular changes are involved in the corpus luteum after heat exposure, a total of 30 early pregnant mice were divided equally into heat stress (HS) and non-HS (NHS) groups (n = 15). Mice in the HS group were exposed to 40.5 ± 0.2 ℃ for 7 consecutive days. Ovaries were collected for immunohistochemistry (IHC), western blot (WB) analysis and transmission electron microscopy (TEM). Serum was collected to determine progesterone by RIA and uteri were collected to count the implantation sites. Results showed that heat exposure increased rectal temperature, decreased body weight and number of implantation sites. WB analysis revealed that ovarian expression of LC3B and Atg7 was up-regulated, while p62 was down-regulated in the HS group. IHC results demonstrated that ovarian staining intensity of LC3B was more intense in the HS group than that of the NHS group. LC3B was mainly localized in the granulosa cells, oocytes and luteal steroidogenic cells of the HS group. TEM results revealed double-layered separated membranes indicative of autophagosomes in the luteal steroidogenic cells of the HS group. Moreover, TEM showed that the mitochondrial cristae became dearth, structure-less, swollen after HS. Additionally, the nucleus expanded and accumulation of lipid droplets increased after HS. Results also showed that heat exposure decreased serum progesterone level and ovarian P450scc expression. These results indicate that HS enhanced autophagy and altered the subcellular structure of luteal steroidogenic cells, which may contribute to interfering with the maintenance of luteal function in early pregnant mice.

Actively priming autophagic cell death with novel transferrin receptor-targeted nanomedicine for synergistic chemotherapy against breast cancer

Recently, considerable attention in the field of cancer therapy has been focused on the mammalian rapamycin target (mTOR), inhibition of which could result in autophagic cell death (ACD). Though novel combination chemotherapy of autophagy inducers with chemotherapeutic agents is extensively investigated, nanomedicine-based combination therapy for ACD remains in infancy. In attempt to actively trigger ACD for synergistic chemotherapy, here we incorporated autophagy inducer rapamycin (RAP) into 7pep-modified PEG-DSPE polymer micelles (7pep-M-RAP) to specifically target and efficiently priming ACD of MCF-7 human breast cancer cells with high expression of transferrin receptor (TfR). Cytotoxic paclitaxel (PTX)-loaded micelle (7pep-M-PTX) was regarded as chemotherapeutic drug model. We discovered that with superior intracellular uptake in vitro and more tumor accumulation of micelles in vivo, 7pep-M-RAP exhibited excellent autophagy induction and synergistic antitumor efficacy with 7pep-M-PTX. Mechanism study further revealed that 7pep-M-RAP and 7pep-M-PTX used in combination provided enhanced efficacy through induction of both apoptosis- and mitochondria-associated autophagic cell death. Together, our findings suggested that the targeted excess autophagy may provide a rational strategy to improve therapeutic outcome of breast cancer, and simultaneous induction of ACD and apoptosis may be a promising anticancer modality.

Ethanol-Induced Autophagy in Sertoli Cells Is Specifically Marked at Androgen-Dependent Stages of the Spermatogenic Cycle: Potential Mechanisms and Implications

In a recent study, we reported that acute ethanol exposure enhanced autophagy in Sertoli cells (SCs) of adult rats. However, further research is needed to clarify the specific spermatogenic stage exhibiting the highest autophagic response, the mechanisms behind such specificity, and the related relevance to sperm. This brief report provides results indicating that stages VII–VIII (androgen-dependent or spermiation stages) of the spermatogenic cycle exhibited more marked autophagic response in acute-ethanol treated rats (ETRs) than other stages based on suppression of androgen receptor (AR), analysis of microtubule-associated protein 1 light chain 3 (LC3) (an autophagosomal marker) immunostaining in SCs, double labeling of LC3 and lysosomal proteins and electron microscopy. Ultrastructural observations and TUNEL method revealed a notable presence of phagocytosed apoptotic germ cells and retained sperm in SCs of ETRs at these specific stages—a finding rarely observed in control testes. In addition, PTEN-induced putative kinase 1 ( PINK1) (a sensor of mitochondrial damage and mitophagy) and giant lipid droplets were found to have accumulated in SCs of ETRs at same stages. Our data show novel findings indicating that stages VII–VIII of the spermatogenic cycle exhibit high levels of autophagy, specifically under stress conditions, as expressed by the term autophagic stages. This stage-specific upregulation of autophagy in SCs may be related to AR suppression, mitochondrial damage, lipid accumulation, and phagocytosis of apoptotic cells. The phenomenon may be an essential part of ensuring the viability of SCs and supporting germ cells in toxic environments.

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.

Wearable Carbon Nanotube-Based Biosensors on Gloves for Lactate

Developing a simple and direct approach for interfacing a sensor and a target analyte is of great interest for fields such as medical diagnosis, threat detection, food quality control, and environmental monitoring. Gloves provide a unique interface for sensing applications. Here, we show for the first time the development of wearable carbon nanotube (CNT)-based amperometric biosensors painted onto gloves as a new sensing platform, used here for the determination of lactate. Three sensor types were studied, configured as: two CNT electrodes; one CNT electrode, and an Ag/AgCl electrode, and two CNT electrodes and an Ag/AgCl electrode. The sensors are constructed by painting the electrodes using CNT or Ag/AgCl inks. By immobilizing lactate oxidase onto the CNT-based working electrodes, the sensors show sensitive detections of lactate. Comparison of sensor performance shows that a combination of CNT and Ag/AgCl is necessary for highly sensitive detection. We anticipate that these findings could open exciting avenues for fundamental studies of wearable bioelectronics, as well as practical applications in fields such as healthcare and defense.

A Method for In Vivo Induction and Ultrastructural Detection of Mitophagy in Sertoli Cells

An emerging body of evidences based on in vitro studies indicate that mitophagy (selective autophagic clearance of damaged mitochondria) is a prosurvival mechanism, specifically under exposure to various stressors. Sertoli cells (SCs) play essential roles in maintenance of spermatogenesis via paracrine interactions with germ cells and other somatic cells in the testis; however, studies investigating mitophagy in SCs are still very few. In this chapter, we give a brief review of mechanisms and detection methods of mitophagy in SCs based on our recent publications on animal models of ethanol toxicity and current literature. In addition, we provide a method for induction and ultrastructural identification of mitophagy in SCs of adult Wistar rats using a single intraperitoneal injection (5 g/kg) of ethanol. Proper understanding of mitophagy features and mechanisms in SCs may have therapeutic implications for infertility associated with alcoholism and other diseases characterized by mitochondrial dysfunction.

Upregulated Autophagy in Sertoli Cells of Ethanol-Treated Rats Is Associated with Induction of Inducible Nitric Oxide Synthase (iNOS), Androgen Receptor Suppression and Germ Cell Apoptosis

This study was conducted to investigate the autophagic response of Sertoli cells (SCs) to acute ethanol toxicity using in vivo and in vitro models. Adult Wistar rats were intraperitoneally injected with either 5 g/kg ethanol or phosphate-buffered saline (for the control group) and sacrificed 0, 3, 6 and 24 h after injection. Compared to the control group, enhanced germ cell apoptosis was observed in the ethanol-treated rats (ETRs) in association with upregulation of iNOS and reduced expression of androgen receptor protein levels in SCs, which were resistant to apoptosis. Meanwhile, autophagy was upregulated in ETR SCs (peaking at 24 h) compared to the control group, as evidenced by transcription factor EB (TFEB) nuclear translocation, enhanced expression of microtubule-associated protein 1 light chain3-II (LC3-II), lysosome-associated membrane protein-2 (LAMP-2), pan cathepsin protein levels and reduced expression of p62. This upregulation of SC autophagy was confirmed ultrastructurally by enhanced formation of autophagic vacuoles and by immunofluorescent double labelling of autophagosomal and lysosomal markers. Study of cultured SCs confirmed enhanced autophagic response to ethanol toxicity, which was cytoprotective based on decreased viability of SCs upon blocking autophagy with 3-methyladenine (3-MA). The results highlighted the molecular mechanisms of prosurvival autophagy in ETR SCs for the first time, and may have significant implications for male fertility.

Ethanol-induced mitophagy in rat Sertoli cells: Implications for male fertility

Autophagy is a pro-survival mechanism involving lysosomal degradation of damaged cellular components following multiple forms of cellular stress. There is currently a lack of literature on the mechanism, and specifically on mitophagy (selective autophagy of damaged pro-apoptotic mitochondria) in Sertoli cells (SCs). Against such a background, the authors induced mitophagy in SCs of adult male rats using a single injection of ethanol (5 g/kg) and observed mitophagy in the SCs via transmission electron microscopy 24 hr later. In addition, we briefly discussed the possible clinical implications of enhanced autophagy and mitophagy in stressed SCs in our model and in other models of acute stress (e.g., heat and transplantation stress). Further studies on SC autophagy are required, as a full understanding of the molecular mechanisms controlling autophagy in stressed SCs may have therapeutic implications for infertility treatment.