Proteomic analysis of testis biopsies in men treated with injectable testosterone undecanoate alone or in combination with oral levonorgestrel as potential male contraceptive

Treatment with injectable testosterone undecanoate (TU) alone or in combination with oral levonorgestrel (LNG) resulted in marked decreases in sperm concentrations. In this study, we used proteomic analyses to examine the cellular/molecular events occurring in the human testis after TU or TU + LNG treatment. We conducted a global proteomic analysis of the human testicular biopsies before and at 2 weeks after TU alone or TU + LNG treatment. Proteins showing significant changes in expression were identified and analyzed. As a result, 17 and 46 protein spots were found with significant differential expression after the treatment with TU alone and TU + LNG, respectively. TU treatment changed the expression of heterogeneous nuclear ribonucleoprotein K (hnRNP K), proteasome inhibitor PI31 subunit (PSMF1), and superoxide dismutase [Mn] mitochondrial precursor (SOD2). These proteins inhibit "assembly", induce cell death, and promote compensatory "cell survival" in the testis. After TU + LNG treatment, "proliferation/cell survival" and "apoptosis/death" were the predominant responses in the testis. TU + LNG treatment inhibited the expression of Prolyl 4-hydroxylase beta subunit (P4HB) and Annexin A2 (Annexin II). These proteins are involved in apoptosis and cell proliferation, respectively. TU + LNG treatment also enhanced the expression of SOD2 and Parvalbumin alpha (Pvalb). These two proteins may protect testicular cells against apoptosis/death and promote cell survival. In conclusion, TU and TU + LNG treatments suppress spermatogenesis through different pathways by changing the expression of different proteins. hnRNP K, PSMF1, SOD2, P4HB, Annexin II, and Pvalb, are key proteins that may be early molecular targets responsible for spermatogenesis suppression induced by hormone treatment.     

HSF2 mRNA在热应激和大剂量11酸睾酮诱导恒河猴生精细胞凋亡中的表达变化

为了探讨HSF2 mRNA在热应激和超生理剂量睾酮诱导恒河猴生精细胞凋亡中的表达变化,我们建立了手术诱导单侧隐睾和注射大剂量11酸睾酮（TU）恒河猴动物模型,应用3′末端标记分析（TUNEL）和原位杂交方法,检测睾丸细胞的凋亡信号和HSF2的表达变化。TUNEL结果显示热应激和超生理剂量睾酮能够诱导生精细胞出现凋亡信号,它分别于处理后第5天和第30天达到最强,表明热应激和睾酮干扰精子发生可能是通过生精细胞凋亡的方式来实现的。HSF2 mRNA水平在生精细胞凋亡早期（凋亡信号达到最强以前）略有降低,而在凋亡高峰期之后其表达急剧下降。Hsf2基因与我们以前研究的Hsp70-2基因的表达具有时间上的相关性,表明HSF2蛋白可能调控Hsp70-2基因的表达,而且HSF2可能通过多种方式影响精子的发生以及抑制生精细胞的凋亡。     

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.     

Effects of hyperthermia on spermatogenesis, apoptosis, gene expression, and fertility in adult male mice.

Testicular heat shock was used to characterize cellular and molecular mechanisms involved in male fertility. This model is relevant because heat shock proteins (HSPs) are required for spermatogenesis and also protect cells from environmental hazards such as heat, radiation, and chemicals. Cellular and molecular methods were used to characterize effects of testicular heat shock (43 degrees C for 20 min) at different times posttreatment. Mating studies confirmed conclusions, based on histopathology, that spermatocytes are the most susceptible cell type. Apoptosis in spermatocytes was confirmed by TUNEL, and was temporally correlated with the expression of stress-inducible Hsp70-1 and Hsp70-3 proteins in spermatocytes. To further characterize gene expression networks associated with heat shock-induced effects, we used DNA microarrays to interrogate the expression of 2208 genes and thousands more expression sequence tags expressed in mouse testis. Of these genes, 27 were up-regulated and 151 were down-regulated after heat shock. Array data were concordant with the disruption of meiotic spermatogenesis, the heat-induced expression of HSPs, and an increase in apoptotic spermatocytes. Furthermore, array data indicated increased expression of four additional non-HSP stress response genes, and eight cell-adhesion, signaling, and signal-transduction genes. Decreased expression was recorded for 10 DNA repair and recombination genes; 9 protein synthesis, folding, and targeting genes; 9 cell cycle genes; 5 apoptosis genes; and 4 glutathione metabolism genes. Thus, the array data identify numerous candidate genes for further analysis in the heat-shocked testis model, and suggest multiple possible mechanisms for heat shock-induced infertility.     

Nitric oxide‐mediated inhibition of NFκB regulates hyperthermia‐induced apoptosis

Ascertaining the upstream regulatory mechanisms of hyperthermia‐induced apoptosis is important to understand the role of hyperthermia in combined modality cancer therapy. Accordingly, we investigated whether (i) hyperthermia‐induced apoptosis is mediated through the nitric oxide (NO) signaling pathway and (ii) inhibition of post‐translational modification of IκBα and down regulation of NFκB‐DNA binding activity is an intermediate step in NO‐dependent apoptosis in MCF‐7 breast cancer cells. For hyperthermia treatment, the cells were exposed to 43°C. Intracellular NO levels measured by the fluorescent intensity of DAF‐2A and iNOS expression by immunobloting revealed an increased level of iNOS dependent NO production after 43°C. Apoptosis measured by Annexin V expression and cell survival by clonogenic assay showed a 20% increase in apoptosis after 43°C treatments. EMSA analysis showed a dose‐dependent inhibition of NFκB‐DNA binding activity. The hyperthermia‐mediated inhibition of NFκB was persistent even after 48 h. Inhibition of NO by L ‐NAME rescued the NFκB‐DNA binding activity and inhibits heat‐induced apoptosis. Similarly, over‐expression of NFκB by transient transfection inhibits heat‐induced apoptosis. These results demonstrate that apoptosis upon hyperthermia exposure of MCF‐7 cells is regulated by NO‐mediated suppression of NFκB. J. Cell. Biochem. 106: 999–1009, 2009. © 2009 Wiley‐Liss, Inc.     

Role of UCH-L1/ubiquitin in acute testicular ischemia-reperfusion injury

The most significant complication of testicular torsion is loss of the testis, which may lead to impaired fertility. Molecular mechanisms how spermatogenesis impairs owing to testicular torsion remain unknown. This investigation, by using mouse model of testicular torsion, was undertaken to gain insight into the cellular and molecular mechanism underlying torsion-induced germ cell loss. Male mice were subjected to 2 h ischemia-inducing torsion, and testes were examined at 24, 48, and 72 h after the repair of torsion (reperfusion). Ischemia-reperfusion (IR) of the testes resulted in germ cell, mostly in spermatogonia, apoptosis, which was revealed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) technique. At 24 h after torsion repair germ cell apoptosis reached peak, then decreased until 72 h repair. Western blots showed that apoptotic proteins (p53, Caspase-3 and -9) gradually were upregulated at 48 h reperfusion, however, anti-apoptotic proteins (Bcl-2 and BDNF) were downregulated in the relevant IR treatment. IR injury induced CHOP protein appearance with maximum expression at 24 h of reperfusion. Furthermore, the germ cell apoptosis triggered downregulation of ubiquitin carboxyl-terminal hydrolase-L1 (UCH-L1) at both mRNA and protein levels. To test further whether ubiquitination was involved in IR stress, both mono- and poly-ubiquitin levels in IR stress condition were examined, which showed that both mono- and poly-ubiquitin expression significantly impaired. These results provide evidences of UCH-L1/ubiquitination signaling to the testis IR injury in vivo.     

Apoptosis,proliferation and presence of estradiol receptors in the testes and Bidder's organ of the toad Rhinella arenarum (Amphibia,Anura)

The dynamic equilibrium between spermatogonial proliferation and testicular apoptosis determines the progression of spermatogenesis in amphibians. Estrogens and their receptors play a central role in regulating spermatogenesis in vertebrates, and in some species of anurans, estradiol (E₂) is involved in the regulation of spermatogonial proliferation and apoptosis of germ cells. Bidder's organ (BO) is a structure characteristic of Bufonidae that has historically been compared to an undeveloped ovary. In adult Rhinella arenarum males, BO is one of the main sources of plasma E₂. The aim of this study was 1) to describe the seasonal variations in testicular apoptosis, spermatogonial proliferation, and cellular proliferation in BO; and 2) to analyze the presence and localization of estrogen receptor β (ERβ) in the testes and BO of R. arenarum. Testicular fragments and BOs from animals collected during the year were labeled with 5‐bromo‐2′‐deoxyuridine (BrdU) and BrdU incorporation was determined using immunohistochemistry. Apoptosis in testicular sections was detected using the TUNEL method, and ERβ localization was assessed using immunohistochemistry in testes and BOs. The results indicate that spermatogonial proliferation is highest during the reproductive season and that cysts of spermatocytes and spermatids undergo apoptosis during the postreproductive season. Furthermore, the proliferation of follicular cells is highest during the reproductive and postreproductive seasons. ERβ was primarily detected by immunolocalization in Sertoli cells, follicular cells, and oocytes. Taken together, these results suggest that cysts that do not form spermatozoa are removed from testes by apoptosis and that estrogens regulate both spermatogenesis and oogenesis in adult males of R. arenarum. J. Morphol. 277:412–423, 2016. © 2015 Wiley Periodicals, Inc.     

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.     

Knockdown of CkrL by shRNA deteriorates hypoxia/reoxygenation‐induced H9C2 cardiomyocyte apoptosis and survival inhibition Via Bax and downregulation of P‐Erk1/2

Integrin β1 subunit and its downstream molecule integrin‐linked kinase and focal adhesion kinase have been confirmed to be essential to cell survival and inhibition of apoptosis and hypoxia/reoxygenation (H/R)‐induced injuries in cardiomyocytes. However, it is still unclear whether CrkL [v‐crk avian sarcoma virus CT‐10 oncogene homolog (Crk)‐like], which acts also as a component of the integrin pathway, could also affect H/R‐induced injuries in the cardiomyocytes. The rat‐derived H9C2 cardiomyocytes were infected with a CrkL small hairpin RNA interference recombinant lentivirus, which knockdowns the endogenous CrkL expression in the cardiomyocytes. Apoptosis, cell proliferation and survival were examined in the H9C2 cardiomyocytes treated with either H/R or not. Results showed that knockdown of CrkL could significantly increase apoptosis and inhibition of the cell proliferation and survival and deteriorate the previously mentioned injuries induced by H/R. In contrast, overexpression of human CrkL could relieve the exacerbation of the previously mentioned injuries induced by CrkL knockdown in the H9C2 cardiomyocytes via regulation of Bax and extracellular signal‐regulated kinase1/2 (p‐ERK1/2). In conclusion, these results confirmed that knockdown of CrkL could deteriorate H/R‐induced apoptosis and cell survival inhibition in rat‐derived H9C2 cardiomyocytes via Bax and downregulation of p‐ERK1/2. It implies that CrkL could mitigate H/R‐induced injuries in the cardiomyocytes. Copyright © 2015 John Wiley & Sons, Ltd.     

Inhibition of Hypoxia Inducible Factor 1α by siRNA‐Induced Apoptosis in Human Retinoblastoma Cells

Hypoxia, which activates the hypoxia inducible factor 1α (HIF‐1α), is an essential feature of retinoblastoma (RB) and contributes to poor prognosis and resistance to conventional therapy. In this study, the effect of HIF‐1α knockdown by small interfering RNA (siRNA) on cell proliferation, apoptosis, and apoptotic pathways of human Y‐79 RB cells was first investigated. Exposure to hypoxia induced the increased expression of HIF‐1α both in mRNA and protein levels. Then, knockdown of HIF‐1α by siRNA_HIF‐1α resulted in inhibition of cell proliferation and induced cell apoptosis in human Y‐79 RB cells under both normoxic and hypoxic conditions, with hypoxic conditions being more sensitive. Furthermore, knockdown of HIF‐1α could enhance hypoxia‐induced slight increase of Bax/Bcl‐2 ratio and activate caspase‐9 and caspase‐3. These results together indicated that suppression of HIF‐1α expression may be a promising strategy for the treatment of human RB in the future.     

Spermatogenesis-preventing substance in Japanese eel

Under fresh-water cultivation conditions, spermatogenesis in the Japanese eel is arrested at an immature stage before initiation of spermatogonial proliferation. A single injection of human chorionic gonadotropin can, however, induce complete spermatogenesis, which suggests that spermatogenesis-preventing substances may be present in eel testis. To determine whether such substances exist, we have applied a subtractive hybridisation method to identify genes whose expression is suppressed after human chorionic gonadotropin treatment in vivo. We found one previously unidentified cDNA clone that was downregulated by human chorionic gonadotropin, and named it 'eel spermatogenesis related substances 21' (eSRS21). A homology search showed that eSRS21 shares amino acid sequence similarity with mammalian and chicken Müllerian-inhibiting substance. eSRS21 was expressed in Sertoli cells of immature testes, but disappeared after human chorionic gonadotropin injection. Expression of eSRS21 mRNA was also suppressed in vitro by 11-ketotestosterone, a spermatogenesis-inducing steroid in eel. To examine the function of eSRS21 in spermatogenesis, recombinant eSRS21 produced by a CHO cell expression system was added to a testicular organ culture system. Spermtogonial proliferation induced by 11-ketotestosterone in vitro was suppressed by recombinant eSRS21. Furthermore, addition of a specific anti-eSRS21 antibody induced spermatogonial proliferation in a germ cell/somatic cell co-culture system. We conclude that eSRS21 prevents the initiation of spermatogenesis and, therefore, suppression of eSRS21 expression is necessary to initiate spermatogenesis. In other words, eSRS21 is a spermatogenesis-preventing substance.     

Apoptosis,onset and maintenance of spermatogenesis: evidence for the involvement of Kit in Kit-haplodeficient mice

Kit/stem cell factor (SCF ) has been reported to be involved in survival and proliferation of male differentiating spermatogonial cells. This kinetics study was designed to assess the role of Kit/SCF during spermatogenesis in mice, and the extent of male programmed germ cell death was measured between 8 and 150 days of age. For this purpose, 129/Sv inbred mice in which one Kit allele was inactivated by an nlslacZ sequence insertion (Kit(W-lacZ/+)) were compared with 129/Sv inbred mice with wild-type alleles at the Kit locus. Four different approaches were used: 1) morphometric study to assess spermatogenesis, 2) flow cytometry to study testicular cell ploidy, 3) in situ end labeling to detect apoptosis, and 4) follow-up of reporter gene expression. Spermatogenesis was lower in Kit(W-lacZ/+) heterozygous mice both at the onset of spermatogenesis and during adulthood. Indeed, greater apoptosis occurred at the onset of spermatogenesis. This was followed in the adult by a smaller seminiferous tubule diameter and a lower ratio between type B spermatogonia and type A stem spermatogonia in Kit(W-lacZ/+) mice compared with Kit(+/+) mice. These differences are probably related to the Kit haplodeficiency, which was the only difference between the two genotypes. Germ cell counts and testicular cell ploidy revealed delayed meiosis in Kit(W-lacZ/+) mice. Reporter gene expression confirmed expression of the Kit gene at the spermatogonial stage and also revealed Kit expression during the late pachytene/diplotene transition. These results suggest involvement of Kit/SCF at different stages of spermatogenesis.     

Apoptose et spermatogenèse

Onset of spermatogenesis is associated with a wave of apoptosis, which limits its efficacy during the first cycles in most mammals. After the first cycles, the actual efficacy of spermatogenesis always remains below the theoretical yield. Among the germinal cells, spermatogonia are the main targets of physiological apoptosis. This physiological apoptosis partly depends on the relationships between germ cells and Sertoli cells. The impact of the Sertoli cell/germ cell number ratio on the efficacy of spermatogenesis is well accepted, the concept of density-dependent regulation in the seminiferous tubule was proposed in the early eighties. Since the steps of spermatogenesis require a continuous progression of the cell cycle rather than an arrest, germ cells might therefore be more sensitive to apoptosis. This may also lead to severe disturbances between proliferation and cell death. The first experiments designed to elucidate the mechanisms of germ cell apoptosis were based on hormonal deprivation or cryptorchidism. However, the link between hormonal or cellular action and cell survival remained to be established. Analysis of signal transduction pathways involved in germ cell apoptosis and their regulation were the next steps. The involvement of bcl-2 family genes has been confirmed, although the expression of some of its members remains more controversial. Data derived from overexpression of some genes (Bcl-2, Bcl-xl) or resulting from gene inactivation (Bax) at the testicular level have highlighted the role of these genes in the control of germ cell apoptosis and have also provided some evidence for the strict requirement for density-dependent regulation of spermatogenesis. More recently, variations in the pattern of expression of these genes or proteins helped to explain some of the discrepancies in the literature. The place of the Fas/Fas ligand system during the first cycle of spermatogenesis remains a matter of debate, with controversies concerning the precise site of expression of this oncogene and its receptor. Conversely, its role in the testis after chemotoxic or radiotoxic treatments is well established. However, the normal fertility of animals with a spontaneous inactivation of Fas or Fas L genes does not support a physiological role of these factors during spermatogenesis. While factors involved in TNF/TNF R1 (Tumor Necrosis Factor) are under study, some data have been reported concerning the role of TRAIL (TNFalpha Related Apoptosis Inducing Ligand) and its active or decoy receptors in the testis. Among the oncogenes which may modulate the apoptotic process, Kit/Stem Cell Factor is particularly interesting, as Kit is expressed in some germ cells and Leydig cells, whereas SCF is expressed by Sertoli cells. Its impact during gonadal development and in the survival and proliferation of differentiated spermatogonia has been clearly established. Using a transgenic mice model, in which the Kit gene was inactivated by the insertion of a nls-lacZ sequence in its first exon, we showed that one single copy of the gene was unable to sustain physiological spermatogenesis and fertility in male mice. Our results also suggest that the Kit gene might be expressed at different steps of spermatogenesis, with different signal transduction pathways and biological actions. Finally, analysis of the signal transduction pathways involved in testicular apoptosis and their mechanisms of control is one of the key steps to a better understanding of both impairment of spermatogenesis and the pathogenesis of certain germ cell tumours.     

Dysregulated circRNA_100876 suppresses proliferation of osteosarcoma cancer cells by targeting microRNA-136

The aim of this study was to explore the regulatory mechanism of circRNA_100876/ microRNA-136 (miR-136) axis in the development and progression of osteosarcoma cancer. Quantitative real-time polymerase chain reaction (RT-qPCR) was used to evaluate the expression levels of circRNA_100876 and miR-136 in osteosarcoma cancer samples and the adjacent nontumor tissues. Then, cell proliferation, cell cycle, apoptosis, and migration of circRNA_100876-knocked down cells were analyzed by in vitro and in vivo experiments, using cell counting kit-8 (CCK-8), flow cytometry, and transwell and tumorigenesis assays. The expression of circRNA_100876 was found to be significantly upregulated in osteosarcoma, and was closely correlated with the tumor size and tumor differentiation degree. In addition, the knockdown of circRNA_100876 could significantly inhibit the tumor growth, both in vitro and in vivo. Flow cytometry and Western blot analysis results showed that the downregulation of circRNA_100876 inhibited osteosarcoma cells proliferation via promoting apoptosis and arresting more cells in the G2/M stage, as suggested by the expression of apoptosis and cell cycle pathway-related proteins, which changed consistently. Furthermore, the level of miR-136 was negatively correlated with the expression of circRNA_100876, and miR-136 inhibitors were able to reverse the suppression of cell proliferation induced by silencing circRNA_100876. Our study demonstrates that the dysregulation of circRNA_100876 could induce apoptosis and arrest the cell cycle at G2/M stage, followed by suppression of cell proliferation in osteosarcoma, while silencing miR-136 could restore the cell growth. Therefore, circRNA_100876 might serve as a promising biomarker and treatment target for osteosarcoma.     

SiRNA‐Mediated Down‐Regulation of CLIC4 Gene Inhibits Cell Proliferation and Accelerates Cell Apoptosis of Mouse Liver Cancer Hca‐F and Hca‐P Cells

This study explored the effects involved in silencing CLIC4 on apoptosis and proliferation of mouse liver cancer Hca‐F and Hca‐P cells. A CLIC4‐target small interfering RNA (siRNA) was designed to compound into two individual complementary oligonucleotide chains. A process of annealing and connection to a pSilencer vector was followed by transfection with Hca‐F and Hca‐P cells. Quantitative real‐time polymerase chain reaction and Western blotting techniques were used to determine CLIC4 mRNA and protein expressions. CCK8 assay and flow cytometry were employed for analysis of the survival and apoptosis rate as well as the cell cycle in an octreotide‐induced apoptosis model. Expressions of caspase 3, caspase 9, and cleaved PARP were measured using Western blotting. The CLIC4 mRNA and protein expressions in Hca‐F and Hca‐P cells transfected by pSilencer‐CLIC4 siRNA plasmid in the blank group displayed remarkably decreased levels of expression, when compared with both the control and negative control (NC) groups. Decreased survival rates and cleaved PARP expression, increased cell apoptosis rate,expressions of caspase 3 and caspase 9 in Hca‐F and Hca‐P cells were detected in groups that had been cultured in a medium containing octreotide. The pSilencer‐CLIC4 siRNA‐2 group when compared with the control and NC groups exhibited decreased survival rates, cleaved PARP expression, increased cell apoptosis rates, and increased expressions of caspase 3 and caspase 9 of Hca‐F and Hca‐P cells. The results demonstrated that siRNA‐induced down‐regulation of CLIC4 could proliferation, while in turn promoting apoptosis of mouse liver cancer Hca‐F and Hca‐P cells. J. Cell. Biochem. 119: 659–668, 2018. © 2017 Wiley Periodicals, Inc.     

The C. elegans TIA‐1/TIAR homolog TIAR‐1 is required to induce germ cell apoptosis

In Caenorhabditis elegans, physiological germ cell apoptosis eliminates more than half of the cells in the hermaphrodite gonad to support gamete quality and germline homeostasis by a still unidentified mechanism. External factors can also affect germ cell apoptosis. The BH3‐only protein EGL‐1 induces germ cell apoptosis when animals are exposed to pathogens or agents that produce DNA damage. DNA damage‐induced apoptosis also requires the nematode p53 homolog CEP‐1. Previously, we found that heat shock, oxidative, and osmotic stresses induce germ cell apoptosis through an EGL‐1 and CEP‐1 independent mechanism that requires the MAPKK pathway. However, we observed that starvation increases germ cell apoptosis by an unknown pathway. Searching for proteins that participate in stress‐induced apoptosis, we found the RNA‐binding protein TIAR‐1 (a homolog of the mammalian TIA‐1/TIAR family of proteins). Here, we show that TIAR‐1 in C. elegans is required to induce apoptosis in the germline under several conditions. We also show that TIAR‐1 acts downstream of CED‐9 (a BCL2 homolog) to induce apoptosis under stress conditions, and apparently does not seem to regulate ced‐4 or ced‐3 mRNAs accumulation directly. TIAR‐1 is expressed ubiquitously in the cytoplasm of the soma as well as the germline, where it sometimes associates with P granules. We show that animals lacking TIAR‐1 expression are temperature sensitive sterile due to oogenesis and spermatogenesis defects. Our work shows that TIAR‐1 is required for proper germline function and demonstrates that this protein is important to induce germ cell apoptosis under several conditions. genesis 51:690–707. © 2013 Wiley Periodicals, Inc.