SPEN (spen family transcription repressor) is a nucleic acid-binding protein putatively involved in repression of gene expression. We hypothesized that SPEN could be involved in general downregulation of the transcription during the heat shock response in mouse spermatogenic cells through its interactions with chromatin. We documented predominant nuclear localization of the SPEN protein in spermatocytes and round spermatids, which was retained after heat shock. Moreover, the protein was excluded from the highly condensed chromatin. Chromatin immunoprecipitation experiments clearly indicated interactions of SPEN with chromatin in vivo. However, ChIP-Seq analyses did not reveal any strong specific peaks both in untreated and heat shocked cells, which might suggest dispersed localization of SPEN and/or its indirect binding to DNA. Using in situ proximity ligation assay we found close in vivo associations of SPEN with MTA1 (metastasis-associated 1), a member of the nucleosome remodeling complex with histone deacetylase activity, which might contribute to interactions of SPEN with chromatin.
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Joanna Korfanty, Tomasz Stokowy, Marek Chadalski, Agnieszka Toma-Jonik, Natalia Vydra, Piotr Widłak, Bartosz Wojtaś, Bartłomiej Gielniewski and Wieslawa Widlak
Andrée-Anne Saindon and Pierre Leclerc
Sperm Adhesion Molecule 1 (SPAM1) is a sperm protein possessing a hyaluronidase domain in its N-terminus and a zona pellucida binding domain in its C-terminus. Our previous studies showed that bovine spermatozoa potentially have 2 SPAM1 isoforms that present different C-terminal domains, different origins (testis and epididymis), and different locations in spermatozoa. In this study, two approaches were taken to characterize the different SPAM1 isoforms. First, 3’-RACE experiments were done to determine the sequence of the 3’ regions of the potential transcripts. Second, by in silico analyses, we aimed to determine whether our antibody that recognizes the N-terminal domain of SPAM1 detects two SPAM1 isoforms or two highly similar, although different, proteins. We found that the 3’ regions of SPAM1 transcripts from bovine testis and caput epididymis were identical. Nevertheless, two transcript variants that differ by 90 nucleotides, encoded by an entire exon, are expressed in both tissues. Only the protein encoded by the longest SPAM1 transcript variant was confirmed in ejaculated bull spermatozoa by mass spectrometry. In silico analyses revealed a highly similar protein to SPAM1, PH-20, that could potentially be recognized by our N-terminal antibody. The presence of PH-20 transcripts was confirmed in bovine testis and the protein is present in ejaculated spermatozoa. Our N-terminal antibody possibly recognizes both SPAM1 and the highly homologous protein PH-20 instead of two SPAM1 isoforms. Identifying the proteins implicated in the fertilization process is crucial in order to elucidate their roles and to better understand the complex process of fertilization.
Adam J Ziecik, Emilia Przygrodzka, Beenu M Jalali and Monika M Kaczmarek
The new corpora lutea (CLs) in pigs are formed from the preovulatory follicles after the luteinizing hormone (LH) surge. However, total autonomy and independence of CLs from LH up to Day 12 of cycle has recently been questioned. Transformation of estrous cycle CL to CL of pregnancy initiated by embryonic signals requires not only the cessation of prostaglandin F2 (PGF2α) supply to the luteal tissue but also needs the CL to overcome luteolytic acquisition and/or changing its sensitivity to PGF2α during Days 12–14 of pregnancy. The luteolytic cascade is prevented by inhibition of lymphocyte infiltration and leucocyte recruitment, limitation of cell apoptosis, upregulation of pregnancy-associated genes and an enhanced antiluteolytic role of PGE2. Our ‘two-signal switch hypothesis’ highlights the importance of post PGF2α and PGE2 receptor signaling pathways activation in CLs during luteolysis and rescue. The ‘luteolytic switch’ involves increased expression of many regression mediators and activation of the post PTGFR signaling pathway. The ‘rescue switch’ initiated by embryonic signals – estradiol 17β and PGE2 – induces post PTGER2/4 pathway, turning the ‘luteolytic switch’ off and triggering activity of genes responsible for CL maintenance. In mid and late pregnancy, CLs are maintained by LH and the synergistic action of metabolic hormones. This paper provides an outline of recent views on CL regression, rescue and maintenance during pregnancy in pigs that conflict with previous paradigms and highlights new findings regarding the actions of prostaglandins, role of microRNAs (miRNA) and immune system and signaling pathways governing the life cycle of porcine CL.
Casey C Nestor, Michelle N Bedenbaugh, Stanley M Hileman, Lique M Coolen, Michael N Lehman and Robert L Goodman
Early work in ewes provided a wealth of information on the physiological regulation of pulsatile gonadotropin-releasing hormone (GnRH) secretion by internal and external inputs. Identification of the neural systems involved, however, was limited by the lack of information on neural mechanisms underlying generation of GnRH pulses. Over the last decade, considerable evidence supported the hypothesis that a group of neurons in the arcuate nucleus that contain kisspeptin, neurokinin B and dynorphin (KNDy neurons) are responsible for synchronizing secretion of GnRH during each pulse in ewes. In this review, we describe our current understanding of the neural systems mediating the actions of ovarian steroids and three external inputs on GnRH pulsatility in light of the hypothesis that KNDy neurons play a key role in GnRH pulse generation. In breeding season adults, estradiol (E2) and progesterone decrease GnRH pulse amplitude and frequency, respectively, by actions on KNDy neurons, with E2 decreasing kisspeptin and progesterone increasing dynorphin release onto GnRH neurons. In pre-pubertal lambs, E2 inhibits GnRH pulse frequency by decreasing kisspeptin and increasing dynorphin release, actions that wane as the lamb matures to allow increased pulsatile GnRH secretion at puberty. Less is known about mediators of undernutrition and stress, although some evidence implicates kisspeptin and dynorphin, respectively, in the inhibition of GnRH pulse frequency by these factors. During the anoestrus, inhibitory photoperiod acting via melatonin activates A15 dopaminergic neurons that innervate KNDy neurons; E2 increases dopamine release from these neurons to inhibit KNDy neurons and suppress the frequency of kisspeptin and GnRH release.
Gabriela Hernández-Silva, Marta Durand, Fernando Larrea and Mayel Chirinos
When levonorgestrel (LNG) is given for emergency contraception during the follicular phase inhibits or delays ovulation, but also induces changes in endometrial secretions that modulate sperm functionality. In order to characterize the female reproductive tract secreted molecules that may affect human spermatozoa, we analyzed changes in the protein content of uterine flushings obtained from women during the periovulatory phase of a control and a LNG-treated menstrual cycle. Lectin affinity analysis and two-dimensional gel electrophoresis of uterine samples showed changes in protein glycosylation pattern and the presence of 31 differentially expressed proteins (8 up- and 23 down-regulated). Mass spectrometry and Western blot analyses of the differential expressed proteins showed lactotransferrin (LTF) as one of the up-regulated molecules by LNG. In this study, LTF exhibited significant dose-related effects on sperm functionality, particularly a decrease of calcium ionophore-induced acrosome reaction and protein tyrosine phosphorylation. Overall, the results indicated that LNG promoted changes in the proteome of uterine secretions that might compromise human sperm capacitation. These data further support the participation of other mechanisms of action of LNG as emergency contraceptive, in addition to those on ovulation.
Lena Walenta, Nina Schmid, J Ullrich Schwarzer, Frank-Michael Köhn, Henryk F Urbanski, Rüdiger Behr, Leena Strauss, Matti Poutanen and Artur Mayerhofer
NLRP3 is part of the NLRP3 inflammasome and a global sensor of cellular damage. It was recently discovered in rodent Sertoli cells. We investigated NLRP3 in mouse, human and non-human primate (marmoset and rhesus macaque) testes, employing immunohistochemistry. Sertoli cells of all species expressed NLRP3, and the expression preceded puberty. In addition, peritubular cells of the adult human testes expressed NLRP3. NLRP3 and associated genes (PYCARD, CASP1, IL1B) were also found in isolated human testicular peritubular cells and the mouse Sertoli cell line TM4. Male infertility due to impairments of spermatogenesis may be related to sterile inflammatory events. We observed that the expression of NLRP3 was altered in the testes of patients suffering from mixed atrophy syndrome, in which tubules with impairments of spermatogenesis showed prominent NLRP3 staining. In order to explore a possible role of NLRP3 in male infertility, associated with sterile testicular inflammation, we studied a mouse model of male infertility. These human aromatase-expressing transgenic mice (AROM+) develop testicular inflammation and impaired spermatogenesis during aging, and the present data show that this is associated with strikingly elevated Nlrp3 expression in the testes compared to WT controls. Interference by aromatase inhibitor treatment significantly reduced increased Nlrp3 levels. Thus, throughout species NLRP3 is expressed by somatic cells of the testis, which are involved in testicular immune surveillance. We conclude that NLRP3 may be a novel player in testicular immune regulation.
Lihua Yao, Mingyang Li, Jingwen Hu, Wangsheng Wang and Minzhi Gao
Polycystic ovary syndrome (PCOS) is a major cause of infertility in women of reproductive age. However, its exact etiology remains unknown. In this study, we sequenced microRNAs (miRNAs) in human follicular fluid and identified 16 downregulated and 3 upregulated miRNAs in PCOS group compared with non-PCOS group. Among the differential expressed miRNAs, miR-335-5p was verified lower abundance in PCOS than non-PCOS group using quantitative real-time polymerase chain reaction. Besides, miR-335-5p negatively correlated with antral follicle count, anti-Müllerian hormone, and total testosterone. Bioinformatics analysis identified serum/glucocorticoid regulated kinase family member 3 (SGK3) as a potential target gene of miR-335-5p. SGK3 is involved in protein kinase B-mammalian target of rapamycin kinase (AKT-mTOR) signaling pathway and cell proliferation. Western blotting and cell counting kit-8 assays demonstrated that miR-335-5p mimic reduced, while miR-335-5p inhibitor increased, SGK3 abundance, AKT-mTOR pathway and cell proliferation in human granulosa-like tumor KGN cells. Dual-luciferase reporter assays showed that miR-335-5p binds to the 3 untranslated region of SGK3 mRNA. Furthermore, miR-335-5p was decreased and SGK3 was elevated in human granulosa cells obtained from PCOS patients as compared with non-PCOS controls. These findings suggested that miR-335-5p is involved in granulosa cells proliferation via reducing SGK3 expression, which might provide a molecular target to improve dysfunctional granulosa cells in patients with PCOS.
Ratana Lim, Gillian Barker and Martha Lappas
Preterm birth continues to be the leading cause of neonatal mortality and morbidities that can extend into adult life. Few treatment options stem from our incomplete understanding of the mechanisms of human labour and delivery. Activation of the inflammatory response in gestational tissues by inflammation and/or infection leads to the production of pro-inflammatory and pro-labour mediators, thus preterm birth. Interferon regulatory factor 5 (IRF5) has recently emerged as an important pro-inflammatory transcription factor involved in acute and chronic inflammation. The aims of this study were to determine the expression of IRF5 in human myometrium from labouring and non-labouring women, and whether IRF5 is involved in the genesis of pro-inflammatory and pro-labour mediators induced by pro-inflammatory cytokines or toll-like receptor (TLR) ligands. IRF5 mRNA and protein expression was significantly higher in human myometrium after spontaneous term labour, compared to non-labouring tissues. IRF5 mRNA expression was also significantly higher in primary myometrial cells treated with the pro-inflammatory cytokines IL1B or TNF. In primary myometrial cells, IRF5 knockdown by siRNA (siIRF5) was associated with significantly decreased expression and or secretion of pro-inflammatory cytokines (IL1A, IL6), chemokines (CXCL8, CCL2), adhesion molecules (ICAM1, VCAM1) and contraction-associated proteins PTGS2, PGF2α and PTGFR when in the presence of IL1B, TNF, fsl-1 (TLR2/6 ligand) or flagellin (TLR5 ligand). siIRF5-transfected cells also displayed decreased NF-κB RELA transcriptional activity in the presence of these preterm birth mediators. Our study suggests a novel role for IRF5 in the regulation of the inflammatory response in human myometrium.
Ha Thi Nguyen, Kurt Jacobs and Claudia Spits
Human pluripotent stem cells have the capacity to self-renew indefinitely and the ability to differentiate into all cell types of a human body. These characteristics instill them with an enormous promise in regenerative medicine, where they could be used in cell, tissue and even organ-based replacement therapy. In this review, we discuss their potential clinical applications and the advantages and pitfalls for the different types of human pluripotent stem cells to transition from the bench to the bedside. We provide an overview of the current clinical trials, and the specific challenges we are still facing, including immune compatibility, suboptimal differentiation, risk of tumour formation and genome instability.
Miguel J Xavier, Lisa A Mitchell, Kristen E McEwan, Rodney J Scott and R John Aitken
The Big Blue λSelect-cII selection system has been employed along with whole-exome sequencing to examine the susceptibility of the male germ line to mutation in two challenging situations (i) exposure to a chemotherapeutic regime including bleomycin, etoposide and cis-platinum (BEP) and (ii) the ageing process. A 3-week exposure to BEP induced complete azoospermia associated with a loss of developing germ cells and extensive vacuolization of Sertoli cell cytoplasm. Following cessation of treatment, spermatozoa first appeared in the caput epididymis after 6 weeks and by 12 weeks motile spermatozoa could be recovered from the cauda, although the count (P < 0.001) and motility (P < 0.01) of these cells were significantly reduced and superoxide generation was significantly elevated (P < 0.001). Despite this increase in free radical generation, no evidence of chromatin instability was detected in these spermatozoa. Furthermore, embryos obtained from females mated at this 12-week time point showed no evidence of an increased mutational load. Similarly, progressive ageing of Big Blue mice had no impact on the quality of the spermatozoa, fertility or mutation frequency in the offspring despite a significant increase in the mutational load carried by somatic tissues such as the liver (P < 0.05). We conclude that the male germ line is highly resistant to mutation in keeping with the disposable soma hypothesis, which posits that genetic integrity in the germ cells will be maintained at the expense of the soma, in light of the former’s sentinel position in safeguarding the stability of the genome.