TAp73 is required for spermatogenesis and the maintenance of male fertility

Isoform-specific disruption of the TP73 gene reveals a critical role for TAp73γ in tumorigenesis via leptin

TP73, a member of the p53 family, is expressed as TAp73 and ΔNp73 along with multiple C-terminal isoforms (α-η). ΔNp73 is primarily expressed in neuronal cells and necessary for neuronal development. Interestingly, while TAp73α is a tumor suppressor and predominantly expressed in normal cells, TAp73 is found to be frequently altered in human cancers, suggesting a role of TAp73 C-terminal isoforms in tumorigenesis. To test this, the TCGA SpliceSeq database was searched and showed that exon 11 (E11) exclusion occurs frequently in several human cancers. We also found that p73α to p73γ isoform switch resulting from E11 skipping occurs frequently in human prostate cancers and dog lymphomas. To determine whether p73α to p73γ isoform switch plays a role in tumorigenesis, CRISPR technology was used to generate multiple cancer cell lines and a mouse model in that Trp73 E11 is deleted. Surprisingly, we found that in E11-deificient cells, p73γ becomes the predominant isoform and exerts oncogenic activities by promoting cell proliferation and migration. In line with this, E11-deficient mice were more prone to obesity and B-cell lymphomas, indicating a unique role of p73γ in lipid metabolism and tumorigenesis. Additionally, we found that E11-deficient mice phenocopies Trp73-deficient mice with short lifespan, infertility, and chronic inflammation. Mechanistically, we showed that Leptin, a pleiotropic adipocytokine involved in energy metabolism and oncogenesis, was highly induced by p73γ,necessary for p73γ-mediated oncogenic activity, and associated with p73α to γ isoform switch in human prostate cancer and dog lymphoma. Finally, we showed that E11-knockout promoted, whereas knockdown of p73γ or Leptin suppressed, xenograft growth in mice. Our study indicates that the p73γ-Leptin pathway promotes tumorigenesis and alters lipid metabolism, which may be targeted for cancer management.

MMPs, ADAMs and ADAMTSs are associated with mammalian sperm fate

Metalloproteinases include matrix metalloproteinases and disintegrin metalloproteinases. They are important members of the ECM degradation and reconstruction process and are associated with tissue development and disease. The ECM is a three-dimensional network of large molecules consisting of a variety of proteins. It is a physical scaffold for organs, and all types of cells can be found within the ECM. The testicle, where sperm are produced, is an organ that is constantly in dynamic flux. Metalloproteinases can regulate testicular tissue development and the maturation of sperm by affecting the ECM. Metalloproteinase disorders can lead to cryptorchidism, azoospermia, poor semen quality and other diseases. As a member of the metalloproteinase family, ADAMTS plays an important role in testicular slippage to the scrotum. ADAM is involved in the fertilization process, and excessive MMP can damage the BTB. In the testis, metalloproteinase stability represents the stability of the extracellular microenvironment in which germ cells are located and is associated with reproductive function. Metalloproteinases have a definite relationship with male reproduction, but the underlying mechanism is still unclear. This paper summarizes the literature on various metalloproteinases in testicular tissue physiology and pathology to elucidate their role in reproductive function and male reproductive mechanisms.

Wuzi-Yanzong-Wan prevents oligoasthenospermia due to TAp73 suppression by affecting cellular junction remodeling in testicular tissue in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Wuzi-Yanzong-Wan (WZYZW) is a classic Chinese herbal preparation, which has a significant clinical efficacy in tonifying the kidney and benefiting the sperm, and is widely used in the treatment of oligoasthenospermia with a long history. TAp73 inhibition results in the decrease of sperm quality, but the therapeutic mechanism of WZYZW on oligoasthenospermia caused by TAp73 gene inhibition remains elusive.

AIMS OF STUDY

The purpose of this study is to investigate whether TAp73 suppression leads to oligoasthenospermia and the application of WZYZW treatment in condition of TAp73 suppression.

METHODOLOGY

C57BL/6 male mice were injected with Pifithrin-α (2.5 mg/kg) intraperitoneally for 30 days to induce TAp73 suppression model, with WZYZW at 1.0, 2.0 and 4.0 g/kg were administrated in parallel. The blood, testis and epididymis were collected, with organ coefficient calculated. Makler sperm counter was used to analyze the density, motility, survival and malformation rate of sperm. Apoptosis of sperm was analyzed by flow cytometry. Serum hormone levels were determined using ELISA. HE staining and transmission electron microscopy (TEM) were used to observe histopathological changes of testis in blood-testis barrier (BTB), ectoplasmic specialization (ES) and other cell junctions. Expressions of cell adhesion factors including TAp73, Integrin-α6, N-cadherin, Nectin-2 and Occludin were determined by RT-PCR and western blotting.

RESULTS

Compared to control mice, TAp73 inhibition dramatically decreased the epididymal coefficient, sperm quality, and serum testosterone (T) level, while increasing apoptosis in sperm in mice. HE staining and TEM showed that the tight junction (TJ) and apical ES structure were seriously abnormal in the testis in mice with TAp73 inhibition. Additionally, the expression of Occludin protein was elevated, while that of TAp73, Integrin-α6, N-cadherin, and Nectin-2 reduced in model mice. WZYZW treatment ameliorated testicular spermatogenic dysfunctions in TAp73 suppressed mice, restoring the decreased sperm quality, serum T level and testicular histopathological changes of TJ and ES, as well as decreasing sperm malformation rate and apoptosis. Moreover, WZYZW reversed the expressions of Occludin, TAp73, Integrin-α6, N-cadherin and Nectin-2 in TAp73 suppressed mice.

CONCLUSIONS

By impairing spermatogenesis and maturation, TAp73 inhibition led to oligoasthenospermia in mice. WZYZW could rescue the oligoasthenospermia associated with TAp73 inhibition via affecting the dynamic remodeling of cellular junctions in testicular tissues in mice.

TP73 Isoform-specific disruption reveals a critical role of TAp73beta in growth suppression and inflammatory response

TP73 is expressed as multiple N- and C-terminal isoforms through two separate promoters or alternative splicing. While N-terminal p73 isoforms have been well studied, very little is known about p73 C-terminal isoforms. Thus, CRISPR was used to delete TP73 Exon13 (E13-KO) to induce p73α to p73β isoform switch. We showed that E13-KO led to decreased cell proliferation and migration and sensitized cells to ferroptosis, which can be reverted by knockdown of TAp73β in E13-KO cells. To understand the biological function of p73β in vivo, we generated a mouse model in that the Trp73 E13 was deleted by CRISPR. We showed that p73α to p73β isoform switch led to increased cellular senescence in mouse embryonic fibroblasts. We also showed that E13-deficient mice exhibited shorter life span and were prone to spontaneous tumors, chronic inflammation and liver steatosis as compared to WT mice. Additionally, we found that the incidence of chronic inflammation and liver steatosis was higher in E13-deficient mice than that in Trp73-deficient mice, suggesting that p73β is a strong inducer of inflammatory response. Mechanistically, we showed that TAp73β was able to induce cysteine dioxygenase 1 (CDO-1), leading to cysteine depletion and subsequently, enhanced ferroptosis and growth suppression. Conversely, knockdown of CDO-1 was able to alleviate the growth suppression and ferroptosis in E13-KO cells. Together, our data suggest that at a physiologically relevant level, TAp73β is a strong inducer of growth suppression but insufficient to compensate for loss of TAp73α in tumor suppression due to aberrant induction of inflammatory response and liver steatosis.

The Role of Long Noncoding RNAs on Male Infertility: A Systematic Review and In Silico Analysis

Male infertility is a complex disorder affecting many couples worldwide. Long noncoding RNAs (lncRNAs) regulate important cellular processes; however, a comprehensive understanding of their role in male infertility is limited. This systematic review investigates the differential expressions of lncRNAs in male infertility or variations in lncRNA regions associated with it. The PRISMA guidelines were used to search Pubmed and Web of Science (1 June 2022). Inclusion criteria were human participants, patients diagnosed with male infertility, and English language speakers. We also performed an in silico analysis investigating lncRNAs that are reported in many subtypes of male infertility. A total of 625 articles were found, and after the screening and eligibility stages, 20 studies were included in the final sample. Many lncRNAs are deregulated in male infertility, and interactions between lncRNAs and miRNAs play an important role. However, there is a knowledge gap regarding the impact of variants found in lncRNA regions. Furthermore, eight lncRNAs were identified as differentially expressed in many subtypes of male infertility. After in silico analysis, gene ontology (GO) and KEGG enrichment analysis of the genes targeted by them revealed their association with bladder and prostate cancer. However, pathways involved in general in tumorigenesis and cancer development of all types, such as p53 pathways, apoptosis, and cell death, were also enriched, indicating a link between cancer and male infertility. This evidence, however, is preliminary. Future research is needed to explore the exact mechanism of action of the identified lncRNAs and investigate the association between male infertility and cancer.

p53 Controls Meiotic Prophase Progression and Crossover Formation

Meiosis initiates with the formation of double strand breaks (DSBs) throughout the genome. To avoid genomic instability, these DSBs need to be correctly repaired by homologous recombination. Surveillance mechanisms involving the DNA damage response (DDR) pathway ATM-CHK2-p53 can detect the persistence of unrepaired DBSs and activate the recombination-dependent arrest at the pachytene stage. However, a complete understanding of p53 functions under normal physiological conditions remains lacking. Here, we report a detailed analysis of the p53 role during meiotic prophase in mice spermatocytes. We show that the absence of p53 regulates prophase progression by slowing down the pachytene stage when the recombination-dependent arrest occurs. Furthermore, our results show that p53 is necessary for proper crossover (CO) formation and localization. Our study contributes to a deeper understanding of p53 roles during the meiotic prophase.

Structural diversity of p63 and p73 isoforms

Abstract

The p53 protein family is the most studied protein family of all. Sequence analysis and structure determination have revealed a high similarity of crucial domains between p53, p63 and p73. Functional studies, however, have shown a wide variety of different tasks in tumor suppression, quality control and development. Here we review the structure and organization of the individual domains of p63 and p73, the interaction of these domains in the context of full-length proteins and discuss the evolutionary origin of this protein family.

Facts

Open questions

Animal models of male subfertility targeted on LanCL1-regulated spermatogenic redox homeostasis

Oxidative stress in spermatozoa is a major contributor to male subfertility, which makes it an informed choice to generate animal models of male subfertility with targeted modifications of the antioxidant systems. However, the critical male germ cell-specific antioxidant mechanisms have not been well defined yet. Here we identify LanCL1 as a major male germ cell-specific antioxidant gene, reduced expression of which is related to human male infertility. Mice deficient in LanCL1 display spermatozoal oxidative damage and impaired male fertility. Histopathological studies reveal that LanCL1-mediated antioxidant response is required for mouse testicular homeostasis, from the initiation of spermatogenesis to the maintenance of viability and functionality of male germ cells. Conversely, a mouse model expressing LanCL1 transgene is protected against high-fat-diet/obesity-induced oxidative damage and subfertility. We further show that germ cell-expressed LanCL1, in response to spermatogenic reactive oxygen species, is regulated by transcription factor specific protein 1 (SP1) during spermatogenesis. This study demonstrates a critical role for the SP1-LanCL1 axis in regulating testicular homeostasis and male fertility mediated by redox balance, and provides evidence that LanCL1 genetically modified mice have attractive applications as animal models of male subfertility.

Prevalence of Certain Urogenital Bacterial Mollicutes in Patients Suffering from Infertility

Introduction

Mollicutes urogenital tract infections are considered a possible cause of infertility worldwide. Genital Mollicutes infections are difficult and impractical to diagnose by culturing or serology. Mollicutes included in this study were Mycoplasma hominis, Ureaplasma urealyticum, and Mycoplasma genitalium. This cross-sectional study aimed to determine the prevalence of M. hominis, U. urealyticum, and M. genitalium genital infections among infertile males and females patients.

Methods

This study included 103 patients who visited Al-Shunar Clinic in Nablus city in Palestine and diagnosed with infertility during January 2018 to October 2018. The semen, urine, and/or vaginal swab specimens collected from patients were examined by PCR for detection of M. hominis, U. urealyticum, and M. genitalium.

Results

A total of 57 semen, 37 urine, and 16 vaginal swab specimens were collected. Out of the 110 examined specimens, 35 (31.8%) were PCR positive for at least one Mollicutes, which were 16 (14.6%) M. hominis, 11 (10%) U. urealyticum, and 8 (7.3%) M. genitalium. Significant association were found between infections of M. hominis and U. urealyticum (P=0.044) and between M. hominis and M. genitalium (P=0.005) infections. M. hominis infection was found in significantly (P=0.048) higher percentage in males (20.6%) in comparison with females (5.7%). On the other hand, M. genitalium infection rate in females (8.6%) was slightly higher than males (7.4%). M. hominis was more prevalent in all age groups except for patient's age group 40–50 years old, where M. genitalium was more prevalent. M. hominis was also more prevalent in all occupation types and among all smokers.

Conclusion

Urogenital infections caused by M. hominis, M. genitalium, and U. urealyticum could be a possible cause of infertility among patients with different age groups, genders, and occupations. Thus, more attention by infertility centers and physicians is required in adopting molecular methods for diagnosis of infections by these microorganisms.

Alternative splicing and MicroRNA: epigenetic mystique in male reproduction

Infertility is rarely life threatening, however, it poses a serious global health issue posing far-reaching socio-economic impacts affecting 12–15% of couples worldwide where male factor accounts for 70%. Functional spermatogenesis which is the result of several concerted coordinated events to produce sperms is at the core of male fertility, Alternative splicing and microRNA (miRNA) mediated RNA silencing (RNAi) constitute two conserved post-transcriptional gene (re)programming machinery across species. The former by diversifying transcriptome signature and the latter by repressing target mRNA activity orchestrate a spectrum of testicular events, and their dysfunctions has several implications in male infertility. This review recapitulates the knowledge of these mechanistic events in regulation of spermatogenesis and testicular homoeostasis. In addition, miRNA payload in sperm, vulnerable to paternal inputs, including unhealthy diet, infection and trauma, creates epigenetic memory to initiate intergenerational phenotype. Naive zygote injection of sperm miRNAs from stressed father recapitulates phenotypes of offspring of stressed father. The epigenetic inheritance of paternal pathologies through miRNA could be a tantalizing avenue to better appreciate ‘Paternal Origins of Health and Disease’ and the power of tiny sperm.

Establishment of an oligoasthenospermia mouse model based on TAp73 gene suppression

Background

Oligoasthenospermia is one of the main causes of male infertility. Researchers usually use chemical drugs to directly damage germ cells to prepare oligoasthenospermia models, which disregards the adhesion and migration between spermatogenic cells and Sertoli cells. TAp73 is a critical regulator of the adhesin of germ cell; thus, we sought to explore a novel oligoasthenospermia model based on TAp73 gene suppression.

Methods

Mice in the Pifithrin-α group were injected intraperitoneally with 2.5 mg/kg Pifithrin-α (TAp73 inhibitor) daily for 30 consecutive days. Reproductive hormone levels and epididymal sperm quality, as well as the network morphology of Sertoli cells were tested.

Results

Sperm density, motility, and the relative protein and mRNA expression of TAp73 and Nectin 2 were obviously decreased in the Pifithrin-α group compared with the normal control group. No significant distinction was observed in the relative mRNA and protein expression of ZO-1. Furthermore, the tight junctions (TJs) and apical ectoplasmic specialization (ES) were destroyed in the Pifithrin-α group.

Conclusion

The above results indicate that we successfully established a new oligoasthenospermia mouse model. This study provides a foundation for further exploration of the roles of TAp73 genes during spermatogenesis and provides new research objects for further oligospermia research and future drug discovery.

Mechanisms of Functional Pleiotropy of p73 in Cancer and Beyond

The transcription factor p73 is a structural and functional homolog of TP53, the most famous and frequently mutated tumor-suppressor gene. The TP73 gene can synthesize an overwhelming number of isoforms via splicing events in 5′ and 3′ ends and alternative promoter usage. Although it originally came into the spotlight due to the potential of several of these isoforms to mimic p53 functions, it is now clear that TP73 has its own unique identity as a master regulator of multifaceted processes in embryonic development, tissue homeostasis, and cancer. This remarkable functional pleiotropy is supported by a high degree of mechanistic heterogeneity, which extends far-beyond the typical mode of action by transactivation and largely relies on the ability of p73 isoforms to form protein–protein interactions (PPIs) with a variety of nuclear and cytoplasmic proteins. Importantly, each p73 isoform carries a unique combination of functional domains and residues that facilitates the establishment of PPIs in a highly selective manner. Herein, we summarize the expanding functional repertoire of TP73 in physiological and oncogenic processes. We emphasize how TP73’s ability to control neurodevelopment and neurodifferentiation is co-opted in cancer cells toward neoneurogenesis, an emerging cancer hallmark, whereby tumors promote their own innervation. By further exploring the canonical and non-canonical mechanistic patterns of p73, we apprehend its functional diversity as the result of a sophisticated and coordinated interplay of: (a) the type of p73 isoforms (b) the presence of p73 interaction partners in the cell milieu, and (c) the architecture of target gene promoters. We suppose that dysregulation of one or more of these parameters in tumors may lead to cancer initiation and progression by reactivating p73 isoforms and/or p73-regulated differentiation programs thereof in a spatiotemporally inappropriate manner. A thorough understanding of the mechanisms supporting p73 functional diversity is of paramount importance for the efficient and precise p73 targeting not only in cancer, but also in other pathological conditions where TP73 dysregulation is causally involved.

Tissue-specific expression of p73 and p63 isoforms in human tissues

p73 and p63 are members of the p53 family that exhibit overlapping and distinct functions in development and homeostasis. The evaluation of p73 and p63 isoform expression across human tissue can provide greater insight to the functional interactions between family members. We determined the mRNA isoform expression patterns of TP73 and TP63 across a panel of 36 human tissues and protein expression within the highest-expressing tissues. TP73 and TP63 expression significantly correlated across tissues. In tissues with concurrent mRNA expression, nuclear co-expression of both proteins was observed in a majority of cells. Using GTEx data, we quantified p73 and p63 isoform expression in human tissue and identified that the α-isoforms of TP73 and TP63 were the predominant isoform expressed in nearly all tissues. Further, we identified a previously unreported p73 mRNA product encoded by exons 4 to 14. In sum, these data provide the most comprehensive tissue-specific atlas of p73 and p63 protein and mRNA expression patterns in human and murine samples, indicating coordinate expression of these transcription factors in the majority of tissues in which they are expressed.

p73 as a Tissue Architect

The TP73 gene belongs to the p53 family comprised by p53, p63, and p73. In response to physiological and pathological signals these transcription factors regulate multiple molecular pathways which merge in an ensemble of interconnected networks, in which the control of cell proliferation and cell death occupies a prominent position. However, the complex phenotype of the Trp73 deficient mice has revealed that the biological relevance of this gene does not exclusively rely on its growth suppression effects, but it is also intertwined with other fundamental roles governing different aspects of tissue physiology. p73 function is essential for the organization and homeostasis of different complex microenvironments, like the neurogenic niche, which supports the neural progenitor cells and the ependyma, the male and female reproductive organs, the respiratory epithelium or the vascular network. We propose that all these, apparently unrelated, developmental roles, have a common denominator: p73 function as a tissue architect. Tissue architecture is defined by the nature and the integrity of its cellular and extracellular compartments, and it is based on proper adhesive cell-cell and cell-extracellular matrix interactions as well as the establishment of cellular polarity. In this work, we will review the current understanding of p73 role as a neurogenic niche architect through the regulation of cell adhesion, cytoskeleton dynamics and Planar Cell Polarity, and give a general overview of TAp73 as a hub modulator of these functions, whose alteration could impinge in many of the Trp73 ^-/- phenotypes.

Small Proline-Rich Protein 2A and 2D Are Regulated by the RBM38-p73 Axis and Associated with p73-Dependent Suppression of Chronic Inflammation

Simple Summary

Small proline-rich protein 2A and 2D (SPRR2A and SPRR2D) are structure proteins of cornified cell envelopes and function as a protective barrier against diverse external insults. However, the role of SPRR2A/2D in chronic inflammation remains unclear. Here, we showed that SPRR2A/2D expression is controlled by a regulatory loop formed by RNA-binding protein RBM38 and tumor suppressor p73. We also found that RBM38-mediated expression of SPRR2A/2D was p73-dependent and that induction of SPRR2A/2D during keratinocyte differentiation was dependent on both p73 and Rbm38. Furthermore, We found that Rbm38^−/−;Trp73^+/− mice exhibited weak expression of SPRR2A/2D in multiple tissues and were susceptible to systemic chronic inflammation. Together, our data reveal that SPRR2A/2D are novel targets of the RBM38-p73 loop and contribute to p73-dependent suppression of chronic inflammation.

Abstract

Small proline-rich protein 2A and 2D (SPRR2A and SPRR2D) provide barrier function in terminally differentiated stratified squamous epithelia through the epidermal differentiation complex. However, little is known how SPRR2A/2D expression is controlled and their role in chronic inflammation. Here, we showed that that SPRR2A/2D expression is controlled by a regulatory loop formed by RNA-binding protein RBM38 and tumor suppressor p73. Specifically, we found that SPRR2A/2D expression was induced by ectopic expression of RBM38 or p73 but suppressed by knockout of Rbm38 or p73. We also found that RBM38-mediated expression of SPRR2A/2D was p73-dependent and that induction of SPRR2A/2D during keratinocyte differentiation was dependent on both p73 and Rbm38. Additionally, we found that SPRR2A/2D expression was closely associated with p73 expression in normal and cancerous tissues. To determine the biological function of the RBM38-p73 loop potentially via SPRR2A/2D, we generated a cohort of wild-type, Rbm38^−/−, Trp73^+/−, and Rbm38^−/−;Trp73^+/− mice. We found that Rbm38^−/−;Trp73^+/− mice had a much shorter lifespan than that for Rbm38^−/−—and to a lesser extent for Trp73^+/− mice—but were less prone to spontaneous tumors than Trp73^+/− or Rbm38^−/− mice. We also found that Rbm38^−/−;Trp73^+/− mice exhibited weak expression of SPRR2A/2D in multiple tissues and were susceptible to systemic chronic inflammation, suggesting that decreased SPRR2A/2D expression is likely responsible for chronic inflammation in Rbm38^−/−;Trp73^+/− mice, leading to a shortened lifespan. Together, our data reveal that SPRR2A/2D are novel targets of the RBM38-p73 loop and contribute to p73-dependent suppression of chronic inflammation.

Novel Gene Regulation in Normal and Abnormal Spermatogenesis

Spermatogenesis is a complex and dynamic process which is precisely controlledby genetic and epigenetic factors. With the development of new technologies (e.g., single-cell RNA sequencing), increasingly more regulatory genes related to spermatogenesis have been identified. In this review, we address the roles and mechanisms of novel genes in regulating the normal and abnormal spermatogenesis. Specifically, we discussed the functions and signaling pathways of key new genes in mediating the proliferation, differentiation, and apoptosis of rodent and human spermatogonial stem cells (SSCs), as well as in controlling the meiosis of spermatocytes and other germ cells. Additionally, we summarized the gene regulation in the abnormal testicular microenvironment or the niche by Sertoli cells, peritubular myoid cells, and Leydig cells. Finally, we pointed out the future directions for investigating the molecular mechanisms underlying human spermatogenesis. This review could offer novel insights into genetic regulation in the normal and abnormal spermatogenesis, and it provides new molecular targets for gene therapy of male infertility.

Isoform-Specific Roles of Mutant p63 in Human Diseases

Simple Summary

The protein p63 belongs to the family of the p53 tumor suppressor. Mouse models have, however, shown that it is not a classical tumor suppressor but instead involved in developmental processes. Mutations in the p63 gene cause several developmental defects in human patients characterized by limb deformation, cleft lip/palate, and ectodermal dysplasia due to p63’s role as a master regulator of epidermal development. In addition, p63 plays a key role as a quality control factor in oocytes and p63 mutations can result either in compromised genetic quality control or premature cell death of all oocytes.

Abstract

The p63 gene encodes a master regulator of epidermal commitment, development, and differentiation. Heterozygous mutations in the DNA binding domain cause Ectrodactyly, Ectodermal Dysplasia, characterized by limb deformation, cleft lip/palate, and ectodermal dysplasia while mutations in in the C-terminal domain of the α-isoform cause Ankyloblepharon-Ectodermal defects-Cleft lip/palate (AEC) syndrome, a life-threatening disorder characterized by skin fragility, severe, long-lasting skin erosions, and cleft lip/palate. The molecular disease mechanisms of these syndromes have recently become elucidated and have enhanced our understanding of the role of p63 in epidermal development. Here we review the molecular cause and functional consequences of these p63-mutations for skin development and discuss the consequences of p63 mutations for female fertility.

Bisphenols Threaten Male Reproductive Health via Testicular Cells

Male reproductive function and health are largely dependent on the testes, which are strictly regulated by their major cell components, i. e., Sertoli, Leydig, and germ cells. Sertoli cells perform a crucial phagocytic function in addition to supporting the development of germ cells. Leydig cells produce hormones essential for male reproductive function, and germ cell quality is a key parameter for male fertility assessment. However, these cells have been identified as primary targets of endocrine disruptors, including bisphenols. Bisphenols are a category of man-made organic chemicals used to manufacture plastics, epoxy resins, and personal care products such as lipsticks, face makeup, and nail lacquers. Despite long-term uncertainty regarding their safety, bisphenols are still being used worldwide, especially bisphenol A. While considerable attention has been paid to the effects of bisphenols on health, current bisphenol-related reproductive health cases indicate that greater attention should be given to these chemicals. Bisphenols, especially bisphenol A, F, and S, have been reported to elicit various effects on testicular cells, including apoptosis, DNA damage, disruption of intercommunication among cells, mitochondrial damage, disruption of tight junctions, and arrest of proliferation, which threaten male reproductive health. In addition, bisphenols are xenoestrogens, which alter organs and cells functions via agonistic or antagonistic interplay with hormone receptors. In this review, we provide in utero, in vivo, and in vitro evidence that currently available brands of bisphenols impair male reproductive health through their action on testicular cells.

P73 C-terminus is dispensable for multiciliogenesis

The p53 family transcriptional factor p73 plays a pivotal role in development. Ablation of p73 results in severe neurodevelopmental defects, chronic infections, inflammation and infertility. In addition to this, Trp73^-\- mice display severe alteration in the ciliated epithelial lining and the full-length N-terminal isoform TAp73 has been implicated in the control of multiciliogenesis transcriptional program. With our recently generated Trp73^Δ13/Δ13 mouse model, we interrogate the physiological role of p73 C-terminal isoforms in vivo. Trp73^Δ13/Δ13 mice lack exon 13 in Trp73 gene, producing an ectopic switch from the C-terminal isoforms p73α to p73β. Trp73^Δ13/Δ13 mice show a pattern of expression of TAp73 comparable to the wild-type littermates, indicating that the α to β switch does not significantly alter the expression of the gene in this cell type. Moreover, Trp73^Δ13/Δ13 do not display any significant alteration in the airway ciliated epithelium, suggesting that in this context p73β can fully substitute the function of the longer isoform p73α. Similarly, Trp73^Δ13/Δ13 ciliated epithelium of the brain ependyma also does appear defective. In this district however expression of TAp73 is not detectable, indicating that expression of the gene might be compensated by alternative mechanisms. Overall our work indicates that C-terminus p73 is dispensable for the multiciliogenesis program and suggests a possible tissue-specific effect of p73 alternative splicing.

The C terminus of p73 is essential for hippocampal development

The p53 family member p73 has a complex gene structure, including alternative promoters and alternative splicing of the 3' UTR. This results in a complex range of isoforms whose biological relevance largely remains to be determined. By deleting exon 13 (which encodes a sterile α motif) from the Trp73 gene, we selectively engineered mice to replace the most abundantly expressed C-terminal isoform, p73α, with a shorter product of alternative splicing, p73β. These mice (Trp73 ^Δ13/Δ13 ) display severe neurodevelopmental defects with significant functional and morphological abnormalities. Replacement of p73α with p73β results in the depletion of Cajal-Retzius (CR) cells in embryonic stages, thus depriving the developing hippocampus of the pool of neurons necessary for correct hippocampal architecture. Consequently, Trp73 ^Δ13/Δ13 mice display severe hippocampal dysgenesis, reduced synaptic functionality and impaired learning and memory capabilities. Our data shed light on the relevance of p73 alternative splicing and show that the full-length C terminus of p73 is essential for hippocampal development.

p53-Related Transcription Targets of TAp73 in Cancer Cells-Bona Fide or Distorted Reality?

Identification of p73 as a structural homolog of p53 fueled early studies aimed at determining if it was capable of performing p53-like functions. This led to a conundrum as p73 was discovered to be hardly mutated in cancers, and yet, TAp73, the full-length form, was found capable of performing p53-like functions, including transactivation of many p53 target genes in cancer cell lines. Generation of mice lacking p73/TAp73 revealed a plethora of developmental defects, with very limited spontaneous tumors arising only at a later stage. Concurrently, novel TAp73 target genes involved in cellular growth promotion that are not regulated by p53 were identified, mooting the possibility that TAp73 may have diametrically opposite functions to p53 in tumorigenesis. We have therefore comprehensively evaluated the TAp73 target genes identified and validated in human cancer cell lines, to examine their contextual relevance. Data from focused studies aimed at appraising if p53 targets are also regulated by TAp73—often by TAp73 overexpression in cell lines with non-functional p53—were affirmative. However, genome-wide and phenotype-based studies led to the identification of TAp73-regulated genes involved in cellular survival and thus, tumor promotion. Our analyses therefore suggest that TAp73 may not necessarily be p53’s natural substitute in enforcing tumor suppression. It has likely evolved to perform unique functions in regulating developmental processes and promoting cellular growth through entirely different sets of target genes that are not common to, and cannot be substituted by p53. The p53-related targets initially reported to be regulated by TAp73 may therefore represent an experimental possibility rather than the reality.

ΔNp63 promotes IGF1 signalling through IRS1 in squamous cell carcinoma

Accumulating evidence has proved that deregulation of ΔNp63 expression plays an oncogenic role in head and neck squamous cell carcinomas (HNSCCs). Besides p63, the type 1-insulin-like growth factor (IGF) signalling pathway has been implicated in HNSCC development and progression. Most insulin/IGF1 signalling converges intracellularly onto the protein adaptor insulin receptor substrate-1 (IRS-1) that transmits signals from the receptor to downstream effectors, including the PI3K/AKT and the MAPK kinase pathways, which, ultimately, promote proliferation, invasion, and cell survival. Here we report that p63 directly controls IRS1 transcription and cellular abundance and fosters the PI3K/AKT and MAPK downstream signalling pathways. Inactivation of ΔNp63 expression indeed reduces tumour cell responsiveness to IGF1 stimulation, and inhibits the growth potential of HNSCC cells. In addition, a positive correlation was observed between p63 and IRS1 expression in human HNSCC tissue arrays and in publicly available gene expression data. Our findings indicate that aberrant expression of ΔNp63 in HNSSC may act as an oncogenic stimulus by altering the IGF signalling pathway.

The Diverse Functions of Mutant 53, Its Family Members and Isoforms in Cancer

The p53 family of proteins has grown substantially over the last 40 years. It started with p53, then p63, p73, isoforms and mutants of these proteins. The function of p53 as a tumour suppressor has been thoroughly investigated, but the functions of all isoforms and mutants and the interplay between them are still poorly understood. Mutant p53 proteins lose p53 function, display dominant-negative (DN) activity and display gain-of-function (GOF) to varying degrees. GOF was originally attributed to mutant p53′s inhibitory function over the p53 family members p63 and p73. It has become apparent that this is not the only way in which mutant p53 operates as a large number of transcription factors that are not related to p53 are activated on mutant p53 binding. This raises the question to what extent mutant p53 binding to p63 and p73 plays a role in mutant p53 GOF. In this review, we discuss the literature around the interaction between mutant p53 and family members, including other binding partners, the functional consequences and potential therapeutics.

Association of UHRF1 gene polymorphisms with oligospermia in Chinese males

BACKGROUND

UHRF1 plays an important role in maintaining DNA methylation patterns during spermatogenesis. This study was performed to evaluate the association between UHRF1 gene variations and infertility in males with oligozoospermia in a Chinese population.

METHODS

In this case-control study of 735 Chinese men, single-nucleotide polymorphism (SNP) genotypes and alleles in the UHRF1 gene were assessed by direct sequencing. The effects of the mutations on UHRF1 transcription were investigated using a dual-luciferase reporter gene assay.

RESULTS

We identified 24 SNPs, including nine SNPs in the promoter region, three in the 5' untranslated region, five in introns, and seven in exons. Interestingly, the genotype frequencies of SNP rs2656927 (P = 0.014) and rs8103849 (P < 0.001) significantly differed between men with oligozoospermia in case group 1 and normozoospermic men. Moreover, four variants (three were novel) were detected only in the patient group, with two in introns and the others in the promoter region. The results of the luciferase assay showed that the -1615C>T-C and -1562A>G-A alleles increased luciferase activity compared with the -1615C>T-T and -1562A>G-G alleles.

CONCLUSIONS

We detected two SNPs in the UHRF1 gene showing a significant difference between the case and control groups. Two screened SNPs affected UHRF1 promoter activity, improving the understanding of the pathophysiology of oligozoospermia.

TAp73 regulates ATP7A: possible implications for ageing-related diseases

The p53 family member p73 controls a wide range of cellular function. Deletion of p73 in mice results in increased tumorigenesis, infertility, neurological defects and altered immune system. Despite the extensive effort directed to define the molecular underlying mechanism of p73 function a clear definition of its transcriptional signature and the extent of overlap with the other p53 family members is still missing. Here we describe a novel TAp73 target, ATP7A a member of a large family of P-type ATPases implicated in human neurogenerative conditions and cancer chemoresistance. Modulation of TAp73 expression influences basal expression level of ATP7A in different cellular models and chromatin immunoprecipitation confirmed a physical direct binding of TAp73 on ATP7A genomic regions. Bioinformatic analysis of expression profile datasets of human lung cancer patients suggests a possible implication of TAp73/ATP7A axis in human cancer. These data provide a novel TAp73-dependent target which might have implications in ageing-related diseases such as cancer and neurodegeneration.

Tissue-specific roles of p73 in development and homeostasis

p73 (TP73) belongs to the p53 family of transcription factors. Its gene locus encodes two opposing types of isoforms, the transcriptionally active TAp73 class and the dominant-negative DNp73 class, which both play critical roles in development and homeostasis in an astonishingly diverse array of biological systems within specific tissues. While p73 has functions in cancer, this Review focuses on the non-oncogenic activities of p73. In the central and peripheral nervous system, both isoforms cooperate in complex ways to regulate neural stem cell survival, self-renewal and terminal differentiation. In airways, oviduct and to a lesser extent in brain ependyma, TAp73 is the master transcriptional regulator of multiciliogenesis, enabling fluid and germ cell transport across tissue surfaces. In male and female reproduction, TAp73 regulates gene networks that control cell-cell adhesion programs within germinal epithelium to enable germ cell maturation. Finally, p73 participates in the control of angiogenesis in development and cancer. While many open questions remain, we discuss here key findings that provide insight into the complex functions of this gene at the organismal, cellular and molecular level.

Genome-wide differential methylation analyses identifies methylation signatures of male infertility

STUDY QUESTION

Do methylation changes in sperm DNA correlate with infertility?

STUDY ANSWER

Loss of spermatogenesis and fertility was correlated with 1680 differentially-methylated CpGs (DMCs) across 1052 genes.

WHAT IS KNOWN ALREADY

Methylation changes in a number of genes have been correlated with reduced sperm count and motility.

STUDY DESIGN, SIZE, DURATION

This case-control study used spermatozoal DNA from 38 oligo-/oligoastheno-zoospermic infertile patients and 26 normozoospermic fertile men.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Genome-wide methylation analysis was undertaken using 450 K BeadChip on spermatozoal DNA from six infertile and six fertile men to identify DMCs. This was followed by deep sequencing of spermatozoal DNA from 32 infertile patients and 20 fertile controls.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 1680 DMCs were identified, out of which 1436 were hypermethylated and 244 were hypomethylated. Classification of DMCs according to the genes identified BCAN, CTNNA3, DLGAP2, GATA3, MAGI2 and TP73 among imprinted genes, SPATA5, SPATA7, SPATA16 and SPATA22 among spermatogenesis-associated genes, KDM4C and JMJD1C, EZH2 and HDAC4 among genes which regulate methylation and gene expression, HLA-C, HLA-DRB6 and HLA-DQA1 among complementation and immune response genes, and CRISPLD1, LPHN3 and CPEB2 among other genes. Genes showing significant differential methylation in deep sequencing, i.e. HOXB1, GATA3, EBF3, BCAN and TCERG1L, are strong candidates for further investigations. The role of chance was ruled out by deep sequencing of select genes.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASON FOR CAUTION

Genome-wide analyses are fairly accurate, but may not be exactly validated in replication studies across all DMCs. We used the 't' test in the genome-wide methylation analysis, whereas other tests could provide a more robust and powerful analysis.

WIDER IMPLICATIONS OF THE FINDINGS

DMCs can serve as markers for inclusion in infertility screening panels, particularly those in the genes showing differential methylation consistent with previous studies. The genes validated by deep sequencing are strong candidates for investigations of their roles in spermatogenesis.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Council of Scientific and Industrial Research (CSIR), Govt. of India with grant number BSC0101 awarded to Rajender Singh. None of the authors has any competing interest to declare.

Expression and clinical significance of p73 in Wilms tumor in children

Expression and clinical significance of p73 in children with Wilms tumor (WT) were investigated. A retrospective analysis was carried out on 50 children diagnosed with WT in the People's Hospital of Rizhao, from July 2013 to January 2015 (study group), and 20 healthy children with similar age and sex who received health examinations in the same hospital during the same period (control group). The relative expression of p73 mRNA in the peripheral blood of each group was detected by reverse transcription-quantitative PCR (RT-qPCR) in order to study the association between p73 and the clinicopathological parameters of WT, as well as the impact of p73 on the patient prognosis. The two groups were not statistically different in respect to the clinical data of patients (P>0.05); the expression level of p73 in the blood samples of the study group was significantly higher than that of the control group (t=11.44, P<0.01); the expression of p73 in the study group was associated with factors, including tumor size, pathological type and lymphatic metastasis. Considering the mean value of the expression of p73 (3.32) as the boundary, the patients with expression value of p73 <3.32 were studied as the low-expression group, and patients with expression value of p73 >3.32 comprised the high-expression group. At the end of the follow-up, the median survival time and the survival rate of the patients in the high-expression group were significantly lower than those of the low-expression group (P<0.05). The high expression of p73 in the peripheral blood of children with WT was positively correlated with the clinical stage of the tumor, and was closely related with the low survival rate of patients.

Transcription factor TAp73 and microRNA-449 complement each other to support multiciliogenesis

Motile cilia serve vital functions in development, homeostasis, and regeneration. We recently demonstrated that TAp73 is an essential transcriptional regulator of respiratory multiciliogenesis. Here, we show that TAp73 is expressed in multiciliated cells (MCCs) of diverse tissues. Analysis of TAp73 mutant animals revealed that TAp73 regulates Foxj1, Rfx2, Rfx3, axonemal dyneins Dnali1 and Dnai1, plays a pivotal role in the generation of MCCs in male and female reproductive ducts, and contributes to fertility. However, the function of MCCs in the brain appears to be preserved despite the loss of TAp73, and robust activity of cilia-related networks is maintained in the absence of TAp73. Notably, TAp73 loss leads to distinct changes in ciliogenic microRNAs: miR34bc expression is reduced, whereas the miR449 cluster is induced in diverse multiciliated epithelia. Among different MCCs, choroid plexus (CP) epithelial cells in the brain display prominent miR449 expression, whereas brain ventricles exhibit significant increase in miR449 levels along with an increase in the activity of ciliogenic E2F4/MCIDAS circuit in TAp73 mutant animals. Conversely, E2F4 induces robust transcriptional response from miR449 genomic regions. To address whether increased miR449 levels in the brain maintain the multiciliogenesis program in the absence of TAp73, we deleted both TAp73 and miR449 in mice. Although loss of miR449 alone led to a mild ciliary defect in the CP, more pronounced ciliary defects and hydrocephalus were observed in the brain lacking both TAp73 and miR449. In contrast, miR449 loss in other MCCs failed to enhance ciliary defects associated with TAp73 loss. Together, our study shows that, in addition to the airways, TAp73 is essential for generation of MCCs in male and female reproductive ducts, whereas miR449 and TAp73 complement each other to support multiciliogenesis and CP development in the brain.

Defects in efferent duct multiciliogenesis underlie male infertility in GEMC1-, MCIDAS- or CCNO-deficient mice

GEMC1 and MCIDAS are geminin family proteins that transcriptionally activate E2F4/5-target genes during multiciliogenesis, including Foxj 1 and Ccno Male mice that lacked Gemc1, Mcidas or Ccno were found to be infertile, but the origin of this defect has remained unclear. Here, we show that all three genes are necessary for the generation of functional multiciliated cells in the efferent ducts that are required for spermatozoa to enter the epididymis. In mice that are mutant for Gemc1, Mcidas or Ccno, we observed a similar spectrum of phenotypes, including thinning of the seminiferous tubule epithelia, dilation of the rete testes, sperm agglutinations in the efferent ducts and lack of spermatozoa in the epididymis (azoospermia). These data suggest that defective efferent duct development is the dominant cause of male infertility in these mouse models, and this likely extends to individuals with the ciliopathy reduced generation of multiple motile cilia with mutations in MCIDAS and CCNO.

Cajal-Retzius neurons are required for the development of the human hippocampal fissure

Cajal-Retzius neurons (CRN) are the main source of Reelin in the marginal zone of the developing neocortex and hippocampus (HC). They also express the transcription factor p73 and are complemented by later-appearing GABAergic Reelin⁺ interneurons. The human dorsal HC forms at gestational week 10 (GW10), when it develops a rudimentary Ammonic plate and incipient dentate migration, although the dorsal hippocampal fissure (HF) remains shallow and contains few CRN. The dorsal HC transforms into the indusium griseum (IG), concurrently with the rostro-caudal appearance of the corpus callosum, by GW14-17. Dorsal and ventral HC merge at the site of the former caudal hem, which is located at the level of the future atrium of the lateral ventricle and closely connected with the choroid plexus. The ventral HC forms at GW11 in the temporal lobe. The ventral HF is wide open at GW14-16 and densely populated by large numbers of CRNs. These are in intimate contact with the meninges and meningeal blood vessels, suggesting signalling through diverse pathways. At GW17, the fissure deepens and begins to fuse, although it is still marked by p73/Reelin⁺ CRNs. The p73KO mouse illustrates the importance of p73 in CRN for HF formation. In the mutant, Tbr1/Reelin⁺ CRNs are born in the hem but do not leave it and subsequently disappear, so that the mutant cortex and HC lack CRN from the onset of corticogenesis. The HF is absent, which leads to profound architectonic alterations of the HC. To determine which p73 isoform is important for HF formation, isoform-specific TAp73- and DeltaNp73-deficient embryonic and early postnatal mice were examined. In both mutants, the number of CRNs was reduced, but each of their phenotypes was much milder than in the global p73KO mutant missing both isoforms. In the TAp73KO mice, the HF of the dorsal HC failed to form, but was present in the ventral HC. In the DeltaNp73KO mice, the HC had a mild patterning defect along with a shorter HF. Complex interactions between both isoforms in CRNs may contribute to their crucial activity in the developing brain.

Sustained protein synthesis and reduced eEF2K levels in TAp73-\- mice brain: a possible compensatory mechanism

The transcription factor p73 is a member of the p53 family, of which the transactivation domain containing isoform (TAp73) plays key roles in brain development and neuronal stem cells. TAp73 also facilitates homoeostasis and prevents oxidative damage in vivo by inducing the expression of its target genes. Recently, we found that in addition to its role in regulation of transcription, TAp73 also affects mRNA translation. In cultured cells, acute TAp73 depletion activates eEF2K, which phosphorylates eEF2 reducing mRNA translation elongation. As a consequence, there is a reduction in global proteins synthesis rates and reprogramming of the translatome, leading to a selective decrease in the translation of rRNA processing factors. Given the dramatic effects of Tap73 depletion in vitro it was important to determine whether similar effects were observed in vivo. Here, we report the surprising finding that in brains of TAp73 KO mice there is a reduced level of eEF2K, which allows protein synthesis rates to be maintained suggesting a compensation model. These data provide new insights to the role of TAp73 in translation regulation and the eEF2K pathway in the brain.

p73 Is Required for Ovarian Follicle Development and Regulates a Gene Network Involved in Cell-to-Cell Adhesion

We report that p73 is expressed in ovarian granulosa cells and that loss of p73 leads to attenuated follicle development, ovulation, and corpus luteum formation, resulting in decreased levels of circulating progesterone and defects in mammary gland branching. Ectopic progesterone in p73-deficient mice completely rescued the mammary branching and partially rescued the ovarian follicle development defects. Performing RNA sequencing (RNA-seq) on transcripts from murine wild-type and p73-deficient antral follicles, we discovered differentially expressed genes that regulate biological adhesion programs. Through modulation of p73 expression in murine granulosa cells and transformed cell lines, followed by RNA-seq and chromatin immunoprecipitation sequencing, we discovered p73-dependent regulation of a gene set necessary for cell adhesion and migration and components of the focimatrix (focal intra-epithelial matrix), a basal lamina between granulosa cells that promotes follicle maturation. In summary, p73 is essential for ovarian folliculogenesis and functions as a key regulator of a gene network involved in cell-to-cell adhesion and migration.

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p73 is required for murine ovarian folliculogenesis and proper corpus luteum formation

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p73 loss leads to defects in progesterone signaling and mammary gland branching

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In murine ovaries, p73 is expressed specifically in granulosa cells

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p73 regulates components of the granulosa cell focimatrix and migration

TAp73 contributes to the oxidative stress response by regulating protein synthesis

TAp73 is a transcription factor that plays key roles in brain development, aging, and cancer. At the cellular level, TAp73 is a critical homeostasis-maintaining factor, particularly following oxidative stress. Although major studies focused on TAp73 transcriptional activities have indicated a contribution of TAp73 to cellular metabolism, the mechanisms underlying its role in redox homeostasis have not been completely elucidated. Here we show that TAp73 contributes to the oxidative stress response by participating in the control of protein synthesis. Regulation of mRNA translation occupies a central position in cellular homeostasis during the stress response, often by reducing global rates of protein synthesis and promoting translation of specific mRNAs. TAp73 depletion results in aberrant ribosomal RNA (rRNA) processing and impaired protein synthesis. In particular, polysomal profiles show that TAp73 promotes the integration of mRNAs that encode rRNA-processing factors in polysomes, supporting their translation. Concurrently, TAp73 depletion causes increased sensitivity to oxidative stress that correlates with reduced ATP levels, hyperactivation of AMPK, and translational defects. TAp73 is important for maintaining active translation of mitochondrial transcripts in response to oxidative stress, thus promoting mitochondrial activity. Our results indicate that TAp73 contributes to redox homeostasis by affecting the translational machinery, facilitating the translation of specific mitochondrial transcripts. This study identifies a mechanism by which TAp73 contributes to the oxidative stress response and describes a completely unexpected role for TAp73 in regulating protein synthesis.

ADAMTS1 and ADAMTS5 metalloproteases produced by Sertoli cells: a potential diagnostic marker in azoospermia

In this study, our aim was to detect protein levels of A Disintegrin and Metalloproteinase with Thrombospondin Motifs 1 and 5 (ADAMTS1 and ADAMTS5) proteases and to examine the effect of in vitro FSH supplementation on protease production in cultured Sertoli cells. The expression of metalloproteases, ADAMTS1, and ADAMTS5 were investigated in Sertoli cell cultures as well as in ejaculate of azoospermic men which then were compared with ejaculates of the fertile control group. A total of 15 azoospermic men, diagnosed as obstructive (OA, n = 5) and nonobstructive (NOA, n = 10) azoospermia were included in the study. ADAMTS1, ADAMTS5 and FSH receptors (FSHR) were found to be expressed 2.56, 2.10, and 2.66-fold less in Sertoli cells of NOA patients, than those of OA (p < 0.05). After rFSH was added onto Sertoli cell cultures of NOA patients, their expression did not increase significantly and did not reach to levels of control group. Evaluation of ejaculates revealed that the expression of ADAMTS1 and ADAMTS5 were insignificantly 1.03 and 1.1-fold higher in OA group (p > 0.05), respectively; however, in the NOA group, their expression were 1.70 and 1.96-fold lower, respectively, when compared with the fertile control group (p < 0.05) which was statistically significant. As a conclusion, the present study has revealed that insufficiency of ADAMTS1 and ADAMTS5 expression in Sertoli cells may have an important role in the etiology of male infertility. As expected due to low FSHR expression, rFSH response is impaired in NOA patients with relatively low ADAMTS expression response; therefore, such patients might hardly benefit from rFSH treatment. Further studies with larger cohorts may reveal ADAMTSs' potential use as a predictive marker for positive sperm retrieval in azoospermic patients who are scheduled to undergo testicular sperm extraction. Abbreviations: ADAM: A Disintegrin and Metalloproteinase; ADAMTS1 and ADAMTS5: A Disintegrin and Metalloproteinase with 10 Thrombospondin Motifs 1 and 5; ADAMTS: A Disintegrin and Metalloproteinase with Thrombospondin; ABP: androgen binding protein; CAMs: cell adhesion molecules; ECM: extracellular matrix; FSH: follicle stimulating hormone; FSHR: FSH receptors; HRP: horseradish peroxidase; MMP: matrix metalloproteinases; MP: metalloproteinases; NOA: nonobstructive azoospermia; OA: obstructive azoospermia; TIMP-1: tissue inhibitor of metalloproteinase-1.

p63 is a key regulator of iRHOM2 signalling in the keratinocyte stress response

Hyperproliferative keratinocytes induced by trauma, hyperkeratosis and/or inflammation display molecular signatures similar to those of palmoplantar epidermis. Inherited gain-of-function mutations in RHBDF2 (encoding iRHOM2) are associated with a hyperproliferative palmoplantar keratoderma and squamous oesophageal cancer syndrome (termed TOC). In contrast, genetic ablation of rhbdf2 in mice leads to a thinning of the mammalian footpad, and reduces keratinocyte hyperproliferation and migration. Here, we report that iRHOM2 is a novel target gene of p63 and that both p63 and iRHOM2 differentially regulate cellular stress-associated signalling pathways in normal and hyperproliferative keratinocytes. We demonstrate that p63-iRHOM2 regulates cell survival and response to oxidative stress via modulation of SURVIVIN and Cytoglobin, respectively. Furthermore, the antioxidant compound Sulforaphane downregulates p63-iRHOM2 expression, leading to reduced proliferation, inflammation, survival and ROS production. These findings elucidate a novel p63-associated pathway that identifies iRHOM2 modulation as a potential therapeutic target to treat hyperproliferative skin disease and neoplasia.

Integrin-β4 is a novel transcriptional target of TAp73

As a member of p53 family, p73 has attracted intense investigations due to its structural and functional similarities to p53. Among more than ten p73 variants, the transactivation (TA) domain-containing isoform TAp73 is the one that imitates the p53's behavior most. TAp73 induces apoptosis and cell cycle arrest, which endows it the capacity of tumour suppression. Also, it can exert diverse biological influences on cells through activating a complex and context dependent transcriptional programme. The transcriptional activities further broaden its roles in more intricate biological processes. In this article, we report that p73 is a positive regulator of a cell adhesion related gene named integrin β4 (ITGB4). This finding may have implications for the dissection of the biological mechanisms underlining p73 functions.

The hypoxic tumour microenvironment

Cancer progression often benefits from the selective conditions present in the tumour microenvironment, such as the presence of cancer-associated fibroblasts (CAFs), deregulated ECM deposition, expanded vascularisation and repression of the immune response. Generation of a hypoxic environment and activation of its main effector, hypoxia-inducible factor-1 (HIF-1), are common features of advanced cancers. In addition to the impact on tumour cell biology, the influence that hypoxia exerts on the surrounding cells represents a critical step in the tumorigenic process. Hypoxia indeed enables a number of events in the tumour microenvironment that lead to the expansion of aggressive clones from heterogeneous tumour cells and promote a lethal phenotype. In this article, we review the most relevant findings describing the influence of hypoxia and the contribution of HIF activation on the major components of the tumour microenvironment, and we summarise their role in cancer development and progression.

Transcriptional regulation of P63 on the apoptosis of male germ cells and three stages of spermatogenesis in mice

Infertility affects 10-15% of couples worldwide, and male factors account for 50%. Spermatogenesis is precisely regulated by genetic factors, and the mutations of genes result in abnormal spermatogenesis and eventual male infertility. The aim of this study was to explore the role and transcriptional regulation of P63 in the apoptosis and mouse spermatogenesis. P63 protein was decreased in male germ cells of P63^(+/-) mice compared with wild-type mice. There was no obvious difference in testis weight, sperm motility, and fecundity between P63^(+/-) and wild-type mice. However, abnormal germ cells were frequently observed in P63^(+/-) mice at 2 months old. Notably, apoptotic male germ cells and the percentage of abnormal sperm were significantly enhanced in P63^(+/-) mice compared to wild-type mice. Spermatogonia, pachytene spermatocytes and round spermatids were isolated from P63^(+/-) and wild-type mice using STA-PUT velocity sedimentation, and they were identified phenotypically with high purities. RNA sequencing demonstrated distinct transcription profiles in spermatogonia, pachytene spermatocytes, and round spermatids between P63^(+/-) mice and wild-type mice. In total, there were 645 differentially expressed genes (DEGs) in spermatogonia, 106 DEGs in pachytene spermatocytes, and 1152 in round spermatids between P63^(+/-) mice and wild-type mice. Real time PCR verified a number of DEGs identified by RNA sequencing. Gene ontology annotation and pathway analyzes further indicated that certain key genes, e.g., Ccnd2, Tgfa, Hes5, Insl3, Kit, Lef1, and Jun were involved in apoptosis, while Dazl, Kit, Pld6, Cdkn2d, Stra8, and Ubr2 were associated with regulating spermatogenesis. Collectively, these results implicate that P63 mediates the apoptosis of male germ cells and regulates three stages of spermatogenesis transcriptionally. This study could provide novel targets for the diagnosis and treatment of male infertility.

Metabolic pathways regulated by TAp73 in response to oxidative stress

Reactive oxygen species are involved in both physiological and pathological processes including neurodegeneration and cancer. Therefore, cells have developed scavenging mechanisms to maintain redox homeostasis under control. Tumor suppressor genes play a critical role in the regulation of antioxidant genes. Here, we investigated whether the tumor suppressor gene TAp73 is involved in the regulation of metabolic adaptations triggered in response to oxidative stress. H₂O₂ treatment resulted in numerous biochemical changes in both control and TAp73 knockout (TAp73−/−) mouse embryonic fibroblasts, however the extent of these changes was more pronounced in TAp73−/− cells when compared to control cells. In particular, loss of TAp73 led to alterations in glucose, nucleotide and amino acid metabolism. In addition, H₂O₂ treatment resulted in increased pentose phosphate pathway (PPP) activity in null mouse embryonic fibroblasts. Overall, our results suggest that in the absence of TAp73, H₂O₂ treatment results in an enhanced oxidative environment, and at the same time in an increased pro-anabolic phenotype. In conclusion, the metabolic profile observed reinforces the role of TAp73 as tumor suppressor and indicates that TAp73 exerts this function, at least partially, by regulation of cellular metabolism.

p73 promotes glioblastoma cell invasion by directly activating POSTN (periostin) expression

Glioblastoma Multiforme is one of the most highly metastatic cancers and constitutes 70% of all gliomas. Despite aggressive treatments these tumours have an exceptionally bad prognosis, mainly due to therapy resistance and tumour recurrence. Here we show that the transcription factor p73 confers an invasive phenotype by directly activating expression of POSTN (periostin, HGNC:16953) in glioblastoma cells. Knock down of endogenous p73 reduces invasiveness and chemo-resistance, and promotes differentiation in vitro. Using chromatin immunoprecipitation and reporter assays we demonstrate that POSTN, an integrin binding protein that has recently been shown to play a major role in metastasis, is a transcriptional target of TAp73. We further show that POSTN overexpression is sufficient to rescue the invasive phenotype of glioblastoma cells after p73 knock down. Additionally, bioinformatics analysis revealed that an intact p73/POSTN axis, where POSTN and p73 expression is correlated, predicts bad prognosis in several cancer types. Taken together, our results support a novel role of TAp73 in controlling glioblastoma cell invasion by regulating the expression of the matricellular protein POSTN.

Non-oncogenic roles of TAp73: from multiciliogenesis to metabolism

The p53 family of transcription factors (p53, p63 and p73) covers a wide range of functions critical for development, homeostasis and health of mammals across their lifespan. Beside the well-established tumor suppressor role, recent evidence has highlighted novel non-oncogenic functions exerted by p73. In particular, p73 is required for multiciliated cell (MCC) differentiation; MCCs have critical roles in brain and airways to move fluids across epithelial surfaces and to transport germ cells in the reproductive tract. This novel function of p73 provides a unifying cellular mechanism for the disparate inflammatory and immunological phenotypes of p73-deficient mice. Indeed, mice with Trp73 deficiency suffer from hydrocephalus, sterility and chronic respiratory tract infections due to profound defects in ciliogenesis and complete loss of mucociliary clearance since MCCs are essential for cleaning airways from inhaled pollutants, pathogens and allergens. Cross-species genomic analyses and functional rescue experiments identify TAp73 as the master transcriptional integrator of ciliogenesis, upstream of previously known central nodes. In addition, TAp73 shows a significant ability to regulate cellular metabolism and energy production through direct transcriptional regulation of several metabolic enzymes, such as glutaminase-2 and glucose-6 phosphate dehydrogenase. This recently uncovered role of TAp73 in the regulation of cellular metabolism strongly affects oxidative balance, thus potentially influencing all the biological aspects associated with p73 function, including development, homeostasis and cancer. Although through different mechanisms, p63 isoforms also contribute to regulation of cellular metabolism, thus indicating a common route used by all family members to control cell fate. At the structural level, the complexity of p73's function is further enhanced by its ability to form heterotetramers with some p63 isoforms, thus indicating the existence of an intrafamily crosstalk that determines the global outcome of p53 family function. In this review, we have tried to summarize all the recent evidence that have emerged on the novel non-oncogenic roles of p73, in an attempt to provide a unified view of the complex function of this gene within its family.

Gene Polymorphism of Matrix Metalloproteinase 9 in Asthenozoospermic Male Subjects

Background:

Matrix metalloproteinase (MMPs) play important roles in the structural and functional properties of reproductive organs. The aim of this study is to determine the prevalence of C-1562T MMP-9 (rs3918242) gene polymorphism in fertile and infertile men. In addition, we aim to determine the association between C-1562T MMP-9 and G-1575A MMP-2 gene polymorphisms.

Materials and Methods:

A total of 400 subjects, including 200 fertile and 200 infertile men, were recruited for this casecontrol study. The allele frequencies and genotype distributions of single nucleotide polymorphism in the promoter regions of MMP-9 (C-1562T) were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The chi-square (χ2) test was used to assess the distribution of genotype frequencies.

Results:

There were no significant differences found in the genotype distributions or allele frequencies between fertile and infertile men for the C-1562T MMP-9 gene polymorphism. The percent of immotile sperm in infertile men with the CC and CT genotypes of C-1562T MMP-9 gene polymorphism significantly differed compared with that of subjects with the TT genotype. The frequency of CC/GA-combined genotypes of C-1562T MMP-9 and G-1575A MMP-2 gene polymorphisms significantly differed in fertile and infertile men (P=0.031).

Conclusion:

Our results suggest that genetic polymorphisms in MMP may impact male fertility.

p53-dependent programmed necrosis controls germ cell homeostasis during spermatogenesis

The importance of regulated necrosis in pathologies such as cerebral stroke and myocardial infarction is now fully recognized. However, the physiological relevance of regulated necrosis remains unclear. Here, we report a conserved role for p53 in regulating necrosis in Drosophila and mammalian spermatogenesis. We found that Drosophila p53 is required for the programmed necrosis that occurs spontaneously in mitotic germ cells during spermatogenesis. This form of necrosis involved an atypical function of the initiator caspase Dronc/Caspase 9, independent of its catalytic activity. Prevention of p53-dependent necrosis resulted in testicular hyperplasia, which was reversed by restoring necrosis in spermatogonia. In mouse testes, p53 was required for heat-induced germ cell necrosis, indicating that regulation of necrosis is a primordial function of p53 conserved from invertebrates to vertebrates. Drosophila and mouse spermatogenesis will thus be useful models to identify inducers of necrosis to treat cancers that are refractory to apoptosis.

Control mechanisms in germ cells mediated by p53 family proteins

Germ cells are totipotent and, in principle, immortal as they are the source for new germ cells in each generation. This very special role requires tight quality control systems. The p53 protein family constitutes one of the most important quality surveillance systems in cells. Whereas p53 has become famous for its role as the guardian of the genome in its function as the most important somatic tumor suppressor, p63 has been nicknamed 'guardian of the female germ line'. p63 is strongly expressed in resting oocytes and responsible for eliminating those that carry DNA double-strand breaks. The third family member, p73, acts later during oocyte and embryo development by ensuring correct assembly of the spindle assembly checkpoint. In addition to its role in the female germ line, p73 regulates cell-cell contacts between developing sperm cells and supporting somatic cells in the male germ line. Here, we review the involvement of the p53 protein family in the development of germ cells with a focus on quality control in the female germ line and discuss medical implications for cancer patients.

Structural Evolution and Dynamics of the p53 Proteins

The family of the p53 tumor suppressive transcription factors includes p73 and p63 in addition to p53 itself. Given the high degree of amino-acid-sequence homology and structural organization shared by the p53 family members, they display some common features (i.e., induction of cell death, cell-cycle arrest, senescence, and metabolic regulation in response to cellular stress) as well as several distinct properties. Here, we describe the structural evolution of the family members with recent advances on the molecular dynamic studies of p53 itself. A crucial role of the carboxy-terminal domain in regulating the properties of the DNA-binding domain (DBD) supports an induced-fit mechanism, in which the binding of p53 on individual promoters is preferentially regulated by the K_OFF over K_ON.