Maternal SENP7 programs meiosis architecture and embryo survival in mouse.

Understanding the mechanisms underlying abnormal egg production and pregnancy loss is significant for human fertility. SENP7, a SUMO poly-chain editing enzyme, has been regarded as a mitotic regulator of heterochromatin integrity and DNA repair. Herein, we report the roles of SENP7 in mammalian reproductive scenario. Mouse oocytes deficient in SENP7 experienced meiotic arrest at prophase I and metaphase I stages, causing a substantial decrease of mature eggs. Hyperaceylation and hypomethylation of histone H3 and up-regulation of Cdc14B/C accompanied by down-regulation of CyclinB1 and CyclinB2 were further recognized as contributors to defective M-phase entry and spindle assembly in oocytes. The spindle assembly checkpoint activated by defective spindle morphogenesis, which was also caused by mislocalization and ubiquitylation-mediated proteasomal degradation of γ-tubulin, blocked oocytes at meiosis I stage. SENP7-depleted embryos exhibited severely defective maternal-zygotic transition and progressive degeneration, resulting in nearly no blastocyst production. The disrupted epigenetic landscape on histone H3 restricted Rad51C loading onto DNA lesions due to elevated HP1α euchromatic deposition, and reduced DNA 5hmC challenged the permissive status for zygotic DNA repair, which induce embryo death. Our study pinpoints SENP7 as a novel determinant in epigenetic programming and major pathways that govern oocyte and embryo development programs in mammals.

SUMOylation: A link to future therapeutics.

SUMOylation, much of a similar process like ubiquitination catches attention across various research groups as a potential therapeutic target to fight various infectious and cancerous diseases. This idea take its strength from recent reports which unearth the molecular mechanisms of SUMOylation and its involvement in important diseases distributed across various kingdoms. At the beginning SUMOylation was considered a process affected only by viral diseases but subsequent reports enlighten its role in diseases caused by bacteria as well. This enhances the SUMOylation canvas and demanded more in-depth study of the process. The present review is an attempt to study the regulatory mechanism of genes when the natural SUMOylation pathway is disturbed, the cross-talk among SUMOylation and other post translational modifications, the role of miRNAs in controlling the function of transcripts, loading of RNA species into exosomes and the possible SUMOylation related therapeutic targets.

Novel Attributions of TREMs in Immunity.

The emerging role of the TREMs (Triggering Receptors Expressed by Myeloid cells) family in inflammation makes it important to explore their molecular mechanisms governing key pathways in inflammatory diseases. The TREMs family interaction with microbial products make it a strong candidate to target inflammatory diseases and raises an important question of its potential as a useful target in inflammatory diseases caused by products other than microbes, for example psoriasis. The interaction of TREMs with various immune responses can be of key importance in handling inflammatory diseases. The well established interaction of TREM-1 with microbial products like LPS and the emerging interactions with products from different important diseases of brain, heart, lungs and skin demands its full investigation as a therapeutic target. The post translational modifications (PTMs) that might regulate the functions of genes are also discussed and its future potential is reviewed. Furthermore, Its close cross talk with TLRs, NLRs and NODs is also reviewed in context of developing novel therapeutics.

Bisphenol AF compromises blood-testis barrier integrity and sperm quality in mice.

The profound influence of environmental chemicals on human health including inducing life-threatening gene mutation has been publicly recognized. Being a substitute for the extensively used endocrine-disrupting chemical BPA, Bisphenol AF (BPAF) has been known as teratogen with developmental toxicities and therefore potentially putting human into the risk of biological hazards. Herein, we deciphered the detrimental effects of BPAF on spermatogenesis and spermiotiliosis in sexual maturity of mice exposing to BPAF (5, 20, 50 mg/kg/d) for consecutive 28 days. BPAF exposure significantly compromises blood-testis barrier integrity and sperm quantity and quality in a dose-dependent manner. Sperms from BPAF exposure mice are featured by severe DNA damage, altered SUMOylation and ubiquitination dynamics and interfered epigenetic inheritance with hypermethylation of H3K27me3 presumably due to the aggregation of cellular reactive oxygen species (ROS). Furthermore, BPAF treatment (50 µM for 24 h) compromises cytoskeleton architecture and tight junction permeability in primary cultured Sertoli cells evidenced by dysfunction of actin regulatory proteins (e.g. Arp3 and Palladin) via activation of ERK signaling, thereby perturbing the privilege microenvironment created by Sertoli cells for spermatogenesis. Overall, our study determines BPAF is deleterious for male fertility, leading to a better appreciation of its toxicological features in our life.

The cohesion stabilizer sororin favors DNA repair and chromosome segregation during mouse oocyte meiosis.

Maintenance and timely termination of cohesion on chromosomes ensures accurate chromosome segregation to guard against aneuploidy in mammalian oocytes and subsequent chromosomally abnormal pregnancies. Sororin, a cohesion stabilizer whose relevance in antagonizing the anti-cohesive property of Wings-apart like protein (Wapl), has been characterized in mitosis; however, the role of Sororin remains unclear during mammalian oocyte meiosis. Here, we show that Sororin is required for DNA damage repair and cohesion maintenance on chromosomes, and consequently, for mouse oocyte meiotic program. Sororin is constantly expressed throughout meiosis and accumulates on chromatins at germinal vesicle (GV) stage/G2 phase. It localizes onto centromeres from germinal vesicle breakdown (GVBD) to metaphase II stage. Inactivation of Sororin compromises the GVBD and first polar body extrusion (PBE). Furthermore, Sororin inactivation induces DNA damage indicated by positive γH2AX foci in GV oocytes and precocious chromatin segregation in MII oocytes. Finally, our data indicate that PlK1 and MPF dissociate Sororin from chromosome arms without affecting its centromeric localization. Our results define Sororin as a determinant during mouse oocyte meiotic maturation by favoring DNA damage repair and chromosome separation, and thereby, maintaining the genome stability and generating haploid gametes.

The role of TACC3 in mitotic spindle organization.

TACC3 regulates spindle organization during mitosis and also regulates centrosome-mediated microtubule nucleation by affecting γ-Tubulin ring complexes. In addition, it interacts with different proteins (such as ch-TOG, clathrin and Aurora-A) to function in mitotic spindle assembly and stability. By forming the TACC3/ch-TOG complex, TACC3 acts as a plus end-tracking protein to promote microtubule elongation. The TACC3/ch-TOG/clathrin complex is formed to stabilize kinetochore fibers by crosslinking adjacent microtubules. Furthermore, the phosphorylation of TACC3 by Aurora-A is important for the formation of TACC3/ch-TOG/clathrin and its recruitment to kinetochore fibers. Recently, the aberrant expression of TACC3 in a variety of human cancers has been linked with mitotic defects. Thus, in this review, we will discuss our current understanding of the biological roles of TACC3 in mitotic spindle organization.

Abce1 orchestrates M-phase entry and cytoskeleton architecture in mouse oocyte.

ATP-binding cassette E1 (ABCE1) is a member of the ATP-binding cassette transporters and essential for diverse biological events regulating abroad range of biological functions including viral infection, cell proliferation, anti-apoptosis, translation initiation and ribosome biogenesis. Here, we discovered that Abce1 also plays indispensable roles in mouse oocyte meiotic progression. In the present study, we examined the expression, localization, and function of Abce1 during mouse oocyte meiotic maturation. Immunostaining and confocal microscopy identified that Abce1 localized as small dots in nucleus in germinal vesicle stage. After germinal vesicle breakdown, it dispersedly localized around the whole spindle apparatus. During the anaphase and telophase stages, Abce1 was just like a cap to localize around the two pole region of spindle but not the midbody and chromosome. Knockdown of Abce1 by specific siRNA injection delayed the resumption of meiosis (GVBD) and affected the extrusion of first polar body. Moreover, the process of spindle assembly and chromosome alignment were severely impaired. Abce1-RNAi led to the dissociation of γ-tubulin and p-MAPK from spindle poles, thus caused mounts of spindle morphology abnormities and chromosome alignment defects, leading to high incidence of aneuploidy. Our findings refresh the knowledge of Abce1 function by exploring its role in oocyte meiotic resumption, spindle assembly and chromosome alignment.

Expression, Localization of SUMO-1, and Analyses of Potential SUMOylated Proteins in Bubalus bubalis Spermatozoa.

Mature spermatozoa have highly condensed DNA that is essentially silent both transcriptionally and translationally. Therefore, post translational modifications are very important for regulating sperm motility, morphology, and for male fertility in general. Protein sumoylation was recently demonstrated in human and rodent spermatozoa, with potential consequences for sperm motility and DNA integrity. We examined the expression and localization of small ubiquitin-related modifier-1 (SUMO-1) in the sperm of water buffalo (Bubalus bubalis) using immunofluorescence analysis. We confirmed the expression of SUMO-1 in the acrosome. We further found that SUMO-1 was lost if the acrosome reaction was induced by calcium ionophore A23187. Proteins modified or conjugated by SUMO-1 in water buffalo sperm were pulled down and analyzed by mass spectrometry. Sixty proteins were identified, including proteins important for sperm morphology and motility, such as relaxin receptors and cytoskeletal proteins, including tubulin chains, actins, and dyneins. Forty-six proteins were predicted as potential sumoylation targets. The expression of SUMO-1 in the acrosome region of water buffalo sperm and the identification of potentially SUMOylated proteins important for sperm function implicates sumoylation as a crucial PTM related to sperm function.

Olaquindox disrupts tight junction integrity and cytoskeleton architecture in mouse Sertoli cells.

Sertoli cells, by creating an immune-privileged and nutrition supporting environment, maintain mammalian spermatogenesis and thereby holds the heart of male fertility. Olaquindox, an effective feed additive in livestock industry, could potentially expose human into the risk of biological hazards due to its genotoxicity and cytotoxicity, highlighting the significance of determining its bio-safety regarding human reproduction. Herein, we deciphered the detrimental effects of olaquindox on male fertility by mechanistically unraveling how olaquindox intervenes blood-testis barrier in mouse. Olaquindox (400 µg/ml) exposure significantly compromised tight junction permeability function, decreased or dislocated the junction proteins (e.g., ZO-1, occludin and N-cadherin) and attenuated mTORC2 signaling pathway in primary Sertoli cells. Furthermore, olaquindox disrupted F-actin architecture through interfering with the expression of actin branching protein complex (CDC42-N-WASP-Arp3) and actin bunding protein palladin. Olaquindox also triggered severely DNA damage and apoptosis while inhibiting autophagic flux in Sertoli cell presumably due to the exacerbated generation of reactive oxygen species (ROS). Pre-treatment with antioxidant N-acetylcysteine effectively ameliorated olaquindox-induced exhaustion of ZO-1 and N-Cadherin proteins, DNA damage and apoptosis. More significantly, olaquindox disrupted the epigenetic status in Sertoli cells with hypermethylation and concomitantly hypoacetylation of H3K9 and H3K27. Overall, our study determines olaquindox targets Sertoli cells to affect BTB function through tight junction proteins and F-actin orgnization, which might disrupt the process of spermatogenesis.

SENP3 grants tight junction integrity and cytoskeleton architecture in mouse Sertoli cells.

Germ cells develop in a sophisticated immune privileged microenvironment provided by specialized junctions contiguous the basement membrane of the adjacent Sertoli cells that constituted the blood-testis barrier (BTB) in seminiferous epithelium of testis in mammals. Deciphering the molecular regulatory machinery of BTB activity is central to improve male fertility and the role of post-translational modification including SUMOylation pathway is one of the key factors. Herein, we unveiled the mystery of the SUMO-2/3 specific protease SENP3 (Sentrin-specific protease 3) in BTB dynamics regulation. SENP3 is predominantly expressed in the nucleus of Sertoli and spermatocyte cells in adult mouse testis, and knockdown of SENP3 compromises tight junction in Sertoli cells by destructing the permeability function with a concomitant decline in trans-epithelial electrical resistance in primary Sertoli cells, which could attribute to the conspicuous dysfunction of tight junction (TJ) proteins (e.g., ZO-1, occludin) at the cell-cell interface due to the inactivation of STAT3. Moreover, SENP3 knockdown disrupts F-actin architecture in Sertoli cells through intervening Rac1/CDC42-N-WASP-Arp2/3 signaling pathway and Profilin-1 abundance. Our study pinpoints SENP3 might be a novel determinant of multiple pathways governing BTB dynamics in testis to support germ cells development in mammals.

Bisphenol AF negatively affects oocyte maturation of mouse in vitro through increasing oxidative stress and DNA damage.

Bisphenol AF (BPAF) is commonly used in industry production as a substitute for Bisphenol A (BPA). Many studies showed that BPAF negatively affect some physiological processes in humans and animals. However, the effects of BPAF on oocyte maturation and its possible mechanisms are sparsely understood. In the present study, we found that 100 µM BPAF exposure affect oocyte maturation with a decreased first polar body extrusion (PBE) rate. Immunofluorescence study displayed that BPAF exposure disrupt the spindle morphology through affecting the function of microtubule organizing centers (MTOCs), which was confirmed by the dysfunction of γ-tubulin and phosphorylated mitogen-activated protein kinase (p-MAPK). As shown by reactive oxygen species (ROS) accumulation, BPAF exposure also induced oxidative stress. Moreover, DNA damage was significantly increased after BPAF exposure, which may be caused by oxidative stress. In addition, histone modification statuses were changed after BPAF exposure, as shown by western blot with decreased expression of H3K9me3 and H3K27ac. Collectively, our current work demonstrated the possibility of BPAF to negatively impact female fertility and revealed the mechanisms that BPAF disrupted mouse oocyte maturation by affecting cytoskeletal dynamics, inducing oxidative stress, increasing DNA damage, and changing the status of epigenetic modifications. This finding can help develop the potential therapies to alleviate oxidative damage to preserve fertility in people who are often exposed to BPAF environment.

The SUMO Protease SENP3 Orchestrates G2-M Transition and Spindle Assembly in Mouse Oocytes.

Oocyte meiosis is a transcription quiescence process and the cell-cycle progression is coordinated by multiple post-translational modifications, including SUMOylation. SENP3 an important deSUMOylation protease has been intensively studied in ribosome biogenesis and oxidative stress. However, the roles of SENP3 in cell-cycle regulation remain enigmatic, particularly for oocyte meiotic maturation. Here, we found that SENP3 co-localized with spindles during oocyte meiosis and silencing of SENP3 severely compromised the M phase entry (germinal vesicle breakdown, GVBD) and first polar body extrusion (PBI). The failure in polar body extrusion was due to the dysfunction of γ-tubulin that caused defective spindle morphogenesis. SENP3 depletion led to mislocalization and a substantial loss of Aurora A (an essential protein for MTOCs localization and spindle dynamics) while irregularly dispersed distribution of Bora (a binding partner and activator of Aurora A) in cytoplasm instead of concentrating at spindles. The SUMO-2/3 but not SUMO-1 conjugates were globally decreased by SENP3 RNAi. Additionally, the spindle assembly checkpoint remained functional upon SENP3 RNAi. Our findings renew the picture of SENP3 function by exploring its role in meiosis resumption, spindle assembly and following polar body emission during mouse oocyte meiotic maturation, which is potentially due to its proteolytic activity that facilitate SUMO-2/3 maturation.

DeSUMOylation: An Important Therapeutic Target and Protein Regulatory Event.

The discovery of the process of small ubiquitin-like modifier (SUMO)-mediated post-translational modification of targets (SUMOylation) in early 1990s proved to be a significant step ahead in understanding mechanistic regulation of proteins and their functions in diverse life processes at the cellular level. The critical step in reversing the SUMOylation pathway is its ability to be dynamically deSUMOylated by SUMO/sentrin-specific protease (SENP). This review is intended to give a brief introduction about the process of SUMOylation, different mammalian deSUMOylating enzymes with special emphasis on their regulation of ribosome biogenesis at the molecular level, and its emerging roles in mitochondrial dynamics that might reveal usefulness of SENPs for therapeutic applications.