The expression of the PIWI family members miwi and mili in mice testis is negatively affected by estrogen

Ameliorative effects of zinc and vitamin E against phthalates-induced reproductive toxicity in male rats

OBJECTIVE

Phthalates (PEs) could cause reproductive harm to males. A mixture of three widely used PEs (MPEs) was used to investigate the ameliorative effects of zinc (Zn) and vitamin E (VE) against male reproductive toxicity.

METHODS

Fifty male SD rats were randomly divided into five groups (n = 10). Rats in MPEs group were orally treated with 160 mg/kg/d MPEs, while rats in MPEs combined Zn and/or VE groups were treated with 160 mg/kg/d MPEs plus 25 mg/kg/d Zn and/or 25 mg/kg/d VE. After intervention for 70 days, it's was measured of male reproductive organs' weight, histopathological observation of sperms and testes, serum hormones, PIWI proteins and steroidogenic proteins.

RESULTS

Compared with control, anogenital distance, testes weight, epididymides weight, and sex hormones were significantly decreased, while the sperm malformation rate was markedly increased in MPEs group (p < .05); the testicular tissues were injured in MPEs group with disordered and decreased spermatids, and arrested spermatogenesis. PIWIL1, PIWIL2, StAR, CYP11A1 and CYP19A1 were down-regulated in MPEs group (p < .05). However, the alterations of these parameters were restored in MPEs combined Zn and/or VE groups (p < .05).

CONCLUSION

Zn and/or VE improved steroid hormone metabolism, and inhibited MPEs' male reproductive toxicity.

Quercetin inhibits testicular toxicity induced by the mixture of three commonly used phthalates in rats

BACKGROUND

Phthalates (PEs), such as butyl benzyl phthalate, dibutyl phthalate and di(2-ethylhexyl) phthalate, are one of the most widely used plasticizers, and humans are increasingly exposed to them. Phytochemical quercetin (Que) is a typical flavonoid with several biological effects, such as antioxidative and anti-inflammatory. The present study was designed to explore the effect of Que on testicular toxicity caused by the mixture of three commonly used PEs (MPEs), and the underlying mechanism. Forty male Sprague-Dawley rats were randomly and equally divided into five groups (n = 8). Rats in control the group were orally treated with the excipient. Rats in the MPEs group were orally administered with 900 mg kg^-1  day^-1 MPEs, whereas rats in the MPEs+L-Que, MPEs+M-Que and MPEs+H-Que groups were simultaneously treated with 900 mg kg^-1  day^-1 MPEs and, respectively, 10, 30 and 90 mg kg^-1  day^-1 Que for 30 days.

RESULTS

Compared with the control group, the testes weight, epididymides weight, serum testosterone, luteinizing hormone, follicle-stimulating hormone and estradiol levels, and anogenital distance in the MPEs group were significantly decreased (P < 0.05). The testicular tissues were injured with atrophy of seminiferous tubules, hyperplasia of Leydig cells and arrest of spermatogenesis in the MPEs group. Testicular steroidogenic proteins (StAR, P450scc, CYP17A1 and 17β-HSD, P450arom) were up-regulated, whereas P-element-induced wimpy testis proteins (PIWIL1 and PIWIL2) were down-regulated in the MPEs group (P < 0.05). However, the alterations of these parameters were inhibited in the MPEs+M-Que and MPEs+H-Que groups.

CONCLUSION

MPEs disturbed steroid hormone metabolism and caused testicular injuries. Que could inhibit testicular toxicity of MPEs, which might relate to the improved regulation of steroid hormone metabolism. © 2022 Society of Chemical Industry.

Genome-Wide Association Study Identifies Genomic Loci of Sex Determination and Gonadosomatic Index Traits in Large Yellow Croaker (Larimichthys crocea)

Larimichthys crocea is one of the traditional marine culture fishes in China, widely distributed in South China Sea, East Sea, and southern Yellow Sea. Sex dimorphism is evident in this species that females present a substantial growth strength than males, suggesting breeding females could obtain more economic benefits in L. crocea aquaculture industry. With the continuous expansion of aquaculture industry, both identifying sex-associated genome region and understanding the genetic basis underlying gonad differentiation and development matter to not only sex control aquaculture but also breeding industry. Thus, genome-wide association analysis (GWAS) of sex determination was conducted with a random breeding population of 905 individuals (including 463 females and 442 males) by ddRAD sequencing. For sex determination, 21 significant single nucleotide polymorphisms (SNPs) in chromosome (Chr) 22 were identified. Surrounding these SNPs, we founded 14 candidate genes, including dmrt1, dmrt3, and piwil2, fam102a, and odf2. The sex-associated region was narrowed down further to 2.4 Mb on Chr22 through F_st scanning and insertion-deletion (InDel) analysis. Besides, 3 SNPs in the supposed sex-determining region on Chr22 were identified as highly associated with gonad differentiation through GWAS on gonadosomatic index (GSI) in 350 males and 231 females. Because of the significant difference of GSI between females and males of L. crocea, GWAS on GSI of different genders was also conducted independently. Finally, we identified a SNP in Chr18 showing genome-wide significant association with male GSI (MGSI) and three genes axl, cyp2a10, and cyp2g1 involved in the gonadal development regulation process of aromatase. Overall, this study explored the genetic basis of sex determination mechanism and provided novel insights into gonad differentiation and development, offering solid genetic support for sex control breeding, marker-assisted selection, and marine resources conservation.

A Comprehensive Molecular and Clinical Analysis of the piRNA Pathway Genes in Ovarian Cancer

Simple Summary

Although ovarian cancer (OC) is one of the most lethal gynecological cancers, its development and progression remain poorly understood. The piRNA pathway is important for transposon defense and genome stability. piRNA maturation and function involve a number of genes known as the piRNA pathway genes. These genes have recently been implicated in cancer development and progression but information about their role in OC is limited. Our work aimed to provide a better understanding of the roles of piRNA pathway genes in OC. Through analyzing changes in the abundance of 10 piRNA pathway genes, we discovered gene expression differences in benign vs. cancer, chemosensitive vs. chemoresistant and post hormone treatment in OC samples and cells. Furthermore, we observed the differential effects of these genes on patient survival and OC cell invasion. Overall, this work supports a role of the piRNA pathway genes in OC progression and encourages further study of their clinical relevance.

Abstract

Ovarian cancer (OC) is one of the most lethal gynecological malignancies, yet molecular mechanisms underlying its origin and progression remain poorly understood. With increasing reports of piRNA pathway deregulation in various cancers, we aimed to better understand its role in OC through a comprehensive analysis of key genes: PIWIL1-4, DDX4, HENMT1, MAEL, PLD6, TDRD1,9 and mutants of PIWIL1 (P1∆17) and PIWIL2 (PL2L60). High-throughput qRT-PCR (n = 45) and CSIOVDB (n = 3431) showed differential gene expression when comparing benign ovarian tumors, low grade OC and high grade serous OC (HGSOC). Significant correlation of disparate piRNA pathway gene expression levels with better progression free, post-progression free and overall survival suggests a complex role of this pathway in OC. We discovered PIWIL3 expression in chemosensitive but not chemoresistant primary HGSOC cells, providing a potential target against chemoresistant disease. As a first, we revealed that follicle stimulating hormone increased PIWIL2 expression in OV-90 cells. PIWIL1, P1∆17, PIWIL2, PL2L60 and MAEL overexpression in vitro and in vivo decreased motility and invasion of OVCAR-3 and OV-90 cells. Interestingly, P1∆17 and PL2L60, induced increased motility and invasion compared to PIWIL1 and PIWIL2. Our results in HGSOC highlight the intricate role piRNA pathway genes play in the development of malignant neoplasms.

Estrogen-ERα signaling and DNA hypomethylation co-regulate expression of stem cell protein PIWIL1 in ERα-positive endometrial cancer cells

Background

We previously identified PIWIL1 as an oncogene involved in endometrial carcinogenesis. However, the mechanism of Piwil1 mediated regulation of tumorigenesis remains poorly understood.

Methods

The expression levels of target genes in endometrial cancer cells were detected by quantitative reverse transcription-PCR (RT-qPCR) and western blotting. Up- or down-regulation of ERα or PIWIL1 was achieved by transient transfection with expressing plasmids or short hairpin RNA (shRNA). Dual-luciferase reporter assays and chromatin immunoprecipitation (ChIP) were used to demonstrate the ERα bound to the half estrogen response element (half-ERE) located in PIWIL1 promoter. The expression of PIWIL1 and ERα in endometrial carcinoma tissues were investigated using immunohistochemistry and RT-qPCR. The proliferation ability of cancer cells were evaluated by MTT. Methylation status of the PIWIL1 promoter was detected by bisulfite sequencing PCR (BSP).

Results

In the present study, we found that PIWIL1 mediated E₂-stimulated cancer cell proliferation. In ERα-positive endometrial cancer cells, we demonstrated that estrogen-ERα signaling significantly up-regulated the expression of PIWIL1, which was mediated by binding of the ERα onto the PIWIL1 promoter. Furthermore, we found that a half-ERE in the PIWIL1 promoter was essential for ERα binding. The PIWIL1 promoter was hypomethylated in ERα-positive endometrial cancer cells. Treatment with 5-aza-deoxycytidine (5-aza-dC) could up-regulate PIWIL1 expression.

Conclusions

These findings uncover a novel molecular mechanism by which estrogen-ERα signaling and DNA hypomethylation co-regulate PIWIL1 expression. These findings provide novel insights into the hormonal regulation of PIWIL1 in endometrial cancer and the PIWIL1’s role in estrogen-stimulated endometrial carcinogenesis.

Effect of ovarian stimulation on the expression of piRNA pathway proteins

PIWI-interacting RNAs (piRNAs) play an important role in gametogenesis, fertility and embryonic development. The current study investigated the effect of different doses of pregnant mare serum gonadotrophin/human chorionic gonadotrophin (PMSG/hCG) and repeated ovarian stimulation (OS) on the expression of the Mili, Miwi, Mael, Tdrd1, Tdrd9, qnd Mitopld genes, which have crucial roles in the biogenesis and function of piRNAs. Here, we found that after treatment with 7.5 I.U. PMSG/hCG and two repeated rounds of OS, both the mRNA and protein levels of Tdrd9, Tdrd1 and Mael showed the greatest decrease in the ovarian tissue, but the plasma E₂ levels showed the strongest increases (p<0.05). However, we found that the Mitopld, Miwi and Mili gene levels were decreased significantly after treatment with 12.5 I.U. PMSG/hCG. Our results suggested that exogenous gonadotropin administration leads to a significant decrease in the expression of the Mili, Miwi, Mael, Tdrd1, Tdrd9 and Mitopld genes, which are critically important in the piRNA pathway, and the changes in the expression levels of Tdrd9, Tdrd1 and Mael may be associated with plasma E₂ levels. New comprehensive studies are needed to reduce the potential effects of OS on the piRNA pathway, which silences transposable elements and maintains genome integrity, and to contribute to the safety of OS.

Zinc supplement ameliorates phthalates-induced reproductive toxicity in male rats

People are inevitably exposed to phthalates (PEs) ubiquitously existing in environment. Our previous studies, simulating the actual situations of people exposure to PEs, have shown that the sub-chronic exposure to low-doses PEs mixture (MIXPs) impaired reproductive function in male rats. Zinc is an important element in maintaining male reproductive functions. However, it is still unknown whether zinc supplement could mitigate PEs-induced male reproductive toxicity or not with sub-chronic low-dose mixture exposure. This study aimed to explore the effect of zinc supplement on the reproductive toxicity caused by sub-chronic MIXPs exposure (160 mg/(kg•body weight)/d, for 90 days) in male rats, and further to reveal the underlying mechanisms. Testosterone (T), FSH and LH in serum, early toxicity indicators in urine, PIWI proteins (PIWIL1 and PIWIL2) expression in testes and pathological examination were performed for toxicity evaluation. Steroidogenic proteins (17β-HSD, StAR, CYP17A1, P450scc and SRD5A) were measured for mechanisms of exploration. The results indicated that zinc supplement could inhibit the T, LH, FSH level decreases in serum, abolish the effect of 5 early toxicity indicators' levels in urine, restrain the alteration of PIWI proteins expression and improve the constructional injury of testes. These effects might be relevant with the suppressed alteration of the expression of steroidogenic proteins induced by MIXPs in rat testicular cells. This work may offer further insights into reducing health risks of MIXPs exposure.

Roles of piwil1 gene in gonad development and gametogenesis in Japanese flounder, Paralichthys olivaceus

PIWI family member piwil1, which associates with Piwi-interacting RNA (piRNA), is responsible in regulation of germ cell differentiation and maintenance of reproductive stem cells. In this study, we analyzed the piwil1 gene in Paralichthys olivaceus. Bioinformatics analysis and structure prediction showed that piwil1 had the conserved domains: PAZ domain and PIWI domain. Expression analysis during embryonic development implied that piwil1 gene was maternally inherited. The tissue distribution showed a sexually dimorphic gene expression pattern, with higher expression level in testis than ovary. In situ hybridization results demonstrated that piwil1 was predominantly distributed in oogonia, oocytes, sertoli cells and spermatocytes. A CpG island was predicted in the 5'-flanking region of piwil1 gene, and its methylation levels showed significant disparity between males and females, indicating that the sexually dimorphic expression of piwil1 gene might be regulated by methylation. Furthermore, we explored the distinct roles of human chorionic gonadotropin and 17α-methyltestosterone in regulating the expression of piwil1, and found that piwil1 was interacting with the HPG axis hormones. These results indicated that piwil1 might play a crucial role in gonadal development and gametogenesis in Paralichthys olivaceus.

Piwil1 gene is regulated by hypothalamic-pituitary-gonadal axis in turbot (Scophthalmus maximus): A different effect in ovaries and testes

As constituent factors of Piwi-interacting RNA (piRNA) pathways, Piwi proteins are essential for germline maintenance and gonadal development. Previous studies show that Piwi-piRNA pathways could be regulated by hypothalamic-pituitary-gonadal (HPG) axis, however, related studies have not been reported in marine species. Here we reported the identification of turbot (Scophthalmus maximus) piwil1 gene, which was abundantly expressed in testis and ovary in a tissue-specific manner. Phylogenetic and genomic structure analyses revealed that piwil1 was conserved in its sequence and function during vertebrate evolution. We also investigated the effects of HPG axis hormones, including human chorionic gonadotropin (hCG), estradiol-17β (E2) and 17α-methyltestosterone (MT), on gonadal piwil1 expression via in vivo and in vitro approaches. In ovary, hCG and E2 suppressed piwil1 expression both in vivo and in vitro, and MT increased piwil1 expression in vivo. In testis, hCG had upregulating effects on piwil1 expression in vivo and in vitro, and MT also increased piwil1 expression in vitro. In addition, E2 suppressed expression of piwil1 in vivo. These results indicated that the decreased or increased expression of piwil1 regulated by hormones might play a crucial role during gonadal differentiation and development in S. maximus.

Identification and expression of piwil2 in turbot Scophthalmus maximus, with implications of the involvement in embryonic and gonadal development

Piwil2, a member of the Argonaute family, is involved in the biogenesis of PIWI-interacting RNAs (piRNAs) and plays an important role in regulating gametogenesis. In the present study, we identified turbot Scophthalmus maximus piwil2 gene, named Smpiwil2, which contained a PAZ domain and a PIWI domain. Sequence comparison, genomic structure and phylogenetic analyses showed that Smpiwil2 is homologous to that of teleosts and tetrapods. The Smpiwil2 transcript showed higher expression in the ovary than in the testis, demonstrating a sexually dimorphic gene expression pattern. In situ hybridization (ISH) showed that Smpiwil2 was expressed in the oogonia and all the stages of oocytes in the ovary as well as in spermatogonia and spermatocytes in the testis. Embryonic expression profile revealed that Smpiwil2 was maternally inherited, and its level was higher from the zygote to the blastula stage and subsequently decreased until hatching. Moreover, a CpG island was predicted to locate in the 5'-flanking region of Smpiwil2 gene, and its methylation levels detected by sodium bisulfite sequencing showed significant disparity between females and males, implying that the sexually dimorphic expression of Smpiwil2 might be regulated by methylation. These results indicated that Smpiwil2 had potentially vital functions in embryonic and gonadal development in this species. In addition, the temporal and sex differences in Smpiwil2 expression indicated that this gene may play different roles in gonadal development of different sexes.

Expression and Regulation of PIWIL-Proteins and PIWI-Interacting RNAs in Rheumatoid Arthritis

Objective

The PIWIL (P-element induced wimpy testis like protein) subfamily of argonaute proteins is essential for Piwi-interacting RNA (piRNA) biogenesis and their function to silence transposons during germ-line development. Here we explored their presence and regulation in rheumatoid arthritis (RA).

Methods

The expression of PIWIL genes in RA and osteoarthritis (OA) synovial tissues and synovial fibroblasts (SF) was analysed by Real-time PCR, immunofluorescence and Western blot. The expression of piRNAs was quantified by next generation small RNA sequencing (NGS). The regulation of PIWI/piRNAs, proliferation and methylation of LINE-1 after silencing of PIWIL genes were studied.

Results

PIWIL2 and 4 mRNA were similarly expressed in synovial tissues and SF from RA and OA patients. However, on the protein level only PIWIL4 was strongly expressed in SF. Using NGS up to 300 piRNAs were identified in all SF without significant differences in expression levels between RA and OASF. Of interest, the analysis of the co-expression of the detected piRNAs revealed a less tightly regulated pattern of piRNA-823, -4153 and -16659 expression in RASF. In RASF and OASF, stimulation with TNFα+IL1β/TLR-ligands further significantly increased the expression levels of PIWIL2 and 4 mRNA and piRNA-16659 was significantly (4-fold) induced upon Poly(I:C) stimulation. Silencing of PIWIL2/4 neither affect LINE-1 methylation/expression nor proliferation of RASF.

Conclusion

We detected a new class of small regulatory RNAs (piRNAs) and their specific binding partners (PIWIL2/4) in synovial fibroblasts. The differential regulation of co-expression of piRNAs in RASF and the induction of piRNA/Piwi-proteins by innate immune stimulators suggest a role in inflammatory processes.

piR-651 promotes tumor formation in non-small cell lung carcinoma through the upregulation of cyclin D1 and CDK4

Piwi-interacting RNAs (piRNAs or piRs) are a novel class of non-coding RNAs that participate in germline development by silencing transposable elements and regulating gene expression. To date, the association between piRNAs and non‑small cell lung carcinoma (NSCLC) has not yet been elucidated. In the present study, we have demonstrated that a significant increase in piR-651 expression occurs in NSCLC. Furthermore, the abnormal expression of piR-651 was associated with cancer progression in the patients with NSCLC. The upregulation of piR-651 in A549 cells caused a significant increase in cell viability and metastasis. The percentage of arrested cells in the G0/G1 phase was lower after piR-651 overexpression compared with the controls. We also examined the expression of oncogenes and cancer suppressor genes following piR-651 overexpression in NSCLC cells. Only the expression levels of cyclin D1 and CDK4 significantly correlated with piR-651 expression both in vivo and in vitro. Furthermore, by injecting nude mice with A549 cells transfected with piR-651 plasmids to establish a xenograft model, we demonstrated that there was a correlation between piR-651 overexpression and tumor growth, which was mediated by cyclin D1 and CDK4. These findings strongly support the notion that piR-651 induces NSCLC progression through the cyclin D1 and CDK4 pathway and it may have applications as a potential diagnostic indicator and therapeutic target in the management of NSCLC.

Small non-coding RNAs and their associated proteins in spermatogenesis

The importance of the gene regulation roles of small non-coding RNAs and their protein partners is of increasing focus. In this paper, we reviewed three main small RNA species which appear to affect spermatogenesis. MicroRNAs (miRNAs) are single stand RNAs derived from transcripts containing stem-loops and hairpins which target corresponding mRNAs and affect their stability or translation. Many miRNA species have been found to be related to normal male germ cell development. The biogenesis of piRNAs is still largely unknown but several models have been proposed. Some piRNAs and PIWIs target transposable elements and it is these that may be active in regulating translation or stem cell maintenance. endo-siRNAs may also participate in sperm development. Some possible interactions between different kinds of small RNAs have even been suggested. We also show that male germ granules are seen to have a close relationship with a considerable number of mRNAs and small RNAs. Those special structures may also participate in sperm development.

PIWIL2 promotes progression of non-small cell lung cancer by inducing CDK2 and Cyclin A expression

Background

PIWI proteins have important roles in tumorigenesis due to their interaction with piRNAs. Recent studies suggest that PIWI proteins affect prognosis of various cancers.

Methods

In the present study, PIWI genes expression was assayed in non-small cell lung cancer (NSCLC). To determine the effects of PIWIL2 on NSCLC cells, overexpression and interference assays were performed using the A549 and H460 cell lines. The tumor formation model was performed to demonstrate the effects of PIWIL2 on tumor formation in vivo.

Results

PIWIL2 was increased both at the RNA and protein level in malignant cancer tissues compared with adjacent normal tissue. Moreover, increased PIWIL2 gene expression was negatively correlated with prognosis in NSCLC patients. Overexpression and interference of PIWIL2 promoted and depressed cell proliferation, respectively. Meanwhile, PIWIL2 interference arrested cells at the G2/M stage. In addition, we found that CDK2 and Cyclin A expression were correlated with PIWIL2 expression. Moreover, transfection of PIWIL2 promoted tumor growth in nude mice.

Conclusion

Our findings shed light on the function of PIWIL2 in NSCLC and suggest potential prognostic and therapeutic value.

Expression profiles of PIWIL2 short isoforms differ in testicular germ cell tumors of various differentiation subtypes

PIWI family proteins have recently emerged as essential contributors in numerous biological processes including germ cell development, stem cell maintenance and epigenetic reprogramming. Expression of some of the family members has been shown to be elevated in tumors. In particular, PIWIL2 has been probed as a potential neoplasia biomarker in many cancers in humans. Previously, PIWIL2 was shown to be expressed in most tumours as a set of its shorter isoforms. In this work, we demonstrated the presence of its 60 kDa (PL2L60A) and 80 kDa (PL2L80A) isoforms in testicular cancer cell lines. We also ascertained the transcriptional boundaries of mRNAs and alternative promoter regions for these PIWIL2 isoforms. Further, we probed a range of testicular germ cell tumor (TGCT) samples and found PIWIL2 to be predominantly expressed as PL2L60A in most of them. Importantly, the levels of both PL2L60A mRNA and protein products were found to vary depending on the differentiation subtype of TGCTs, i.e., PL2L60A expression is significantly higher in undifferentiated seminomas and appears to be substantially decreased in mixed and nonseminomatous TGCTs. The higher level of PL2L60A expression in undifferentiated TGCTs was further validated in the model system of retinoic acid induced differentiation in NT2/D1 cell line. Therefore, both PL2L60A mRNA and protein abundance could serve as an additional marker distinguishing between seminomas and nonseminomatous tumors with different prognosis and therapy approaches.

Elevated expression of Piwi and piRNAs in ovaries of triploid crucian carp

Increasing piRNAs provide RNA-interference pathways to regulate transposons and gene expression in germline cells. We demonstrate that Piwi transcripts are exclusively expressed in adult testes and ovaries in teleosts, with triploids showing the highest Piwi expression in the ovaries. Studies in vivo and in vitro showed that hCG and E2 treatment suppressed Piwi expression. We further cloned 200 small RNAs in the three kinds of fish. Seven piRNAs were obtained from all the three different ploidy fishes. During ovulation, five piRNAs showed significantly higher expression in the ovaries of sterile triploids than fertile diploids and tetraploids. Furthermore, E2 suppressed the expression of the six piRNAs at different levels in vivo and in vitro. The present study bridges the gap between the HPG axis and Piwi-piRNA pathway by suggesting that a dysfunctional HPG axis abrogated the piRNA suppression in triploid fish.

Suppression effect of LHRH-A and hCG on Piwi expression in testis of Nile tilapia Oreochromis niloticus

Piwi proteins as constituent factors of the piRNA pathway are required for germline maintenance, meiosis and gonad development. Previous study showed hCG could regulate the Piwi expression in ovary of teleosts. In this study, we revealed effects of LHRH-A and hCG on Piwi expression in testis of tilapia using Real-time PCR and Western blot. Both in vivo and in vitro study suggest that LHRH-A and hCG significantly down-regulated Piwil-1 and Piwil-2 in mRNA or protein levels compared with controls. Meanwhile, tissue and cell distribution showed that Piwi proteins were mainly expressed in spermatocytes rather than mature sperms. These results indicated that HPG suppresses Piwis which may play a crucial role in testis differentiation and development.