Platelet RNA enables accurate detection of ovarian cancer: an intercontinental, biomarker identification study

Platelets are reprogrammed by cancer via a process called education, which favors cancer development. The transcriptional profile of tumor-educated platelets (TEPs) is skewed and therefore practicable for cancer detection. This intercontinental, hospital-based, diagnostic study included 761 treatment-naïve inpatients with histologically confirmed adnexal masses and 167 healthy controls from nine medical centers (China, n = 3; Netherlands, n = 5; Poland, n = 1) between September 2016 and May 2019. The main outcomes were the performance of TEPs and their combination with CA125 in two Chinese (VC1 and VC2) and the European (VC3) validation cohorts collectively and independently. Exploratory outcome was the value of TEPs in public pan-cancer platelet transcriptome datasets. The AUCs for TEPs in the combined validation cohort, VC1, VC2, and VC3 were 0.918 (95% CI 0.889-0.948), 0.923 (0.855-0.990), 0.918 (0.872-0.963), and 0.887 (0.813-0.960), respectively. Combination of TEPs and CA125 demonstrated an AUC of 0.922 (0.889-0.955) in the combined validation cohort; 0.955 (0.912-0.997) in VC1; 0.939 (0.901-0.977) in VC2; 0.917 (0.824-1.000) in VC3. For subgroup analysis, TEPs exhibited an AUC of 0.858, 0.859, and 0.920 to detect early-stage, borderline, non-epithelial diseases and 0.899 to discriminate ovarian cancer from endometriosis. TEPs had robustness, compatibility, and universality for preoperative diagnosis of ovarian cancer since it withstood validations in populations of different ethnicities, heterogeneous histological subtypes, and early-stage ovarian cancer. However, these observations warrant prospective validations in a larger population before clinical utilities.

Abstract LB168: Platelet RNA signature enables early and accurate detection of ovarian cancer: An intercontinental, biomarker identification study

Background: Morpho-physiological alternations of platelets provided a rationale to harness RNA sequencing of tumor-educated platelets (TEPs) for preoperative diagnosis of cancer. Timely, accurate, and non-invasive detection of ovarian cancer in women with adnexal masses presents a significant clinical challenge.

Patients and Methods: This intercontinental, hospital-based, diagnostic study included 761 treatment-naïve inpatients with histologically confirmed adnexal masses and 167 healthy controls from nine medical centers (China, n=3; Netherlands, n=5; Poland, n=1) between September 2016 and May 2019. The main outcomes were the performance of TEPs and their combination with CA125 in two Chinese (VC1 and VC2) and the European (VC3) validation cohorts collectively and independently. Exploratory outcome was the value of TEPs in public pan-cancer platelet transcriptome datasets.

Results: The AUCs for TEPs in the combined validation cohort, VC1, VC2, and VC3 were 0.918 (95% CI 0.889-0.948), 0.923 (0.855-0.990), 0.918 (0.872-0.963), and 0.887 (0.813-0.960), respectively. Combination of TEPs and CA125 demonstrated an AUC of 0.922 (0.889-0.955) in the combined validation cohort; 0.955 (0.912-0.997) in VC1; 0.939 (0.901-0.977) in VC2; 0.917 (0.824-1.000) in VC3. For subgroup analysis, TEPs exhibited an AUC of 0.858, 0.859, and 0.920 to detect early-stage, borderline, non-epithelial diseases and 0.899 to discriminate ovarian cancer from endometriosis. Analysis of public datasets suggested that TEPs had potential to detect multiple malignancies (Table 1).

Conclusions: TEPs had robustness, compatibility, and universality for preoperative diagnosis of ovarian cancer since it withstood validations in populations of different ethnicities, heterogeneous histological subtypes, early-stage ovarian cancer as well as other malignancies. However, these observations warrant prospective validations in a larger population before clinical utilities.

Table 1. Performance for TEPs in public pan-cancer datasets. Disease n Healthy Control AUC, area under the curve (95% CI) Women NSCLC (non-small-cell lung cancer) 126 77 0.758 (0.691-0.825) Breast cancer 38 77 0.817 (0.726-0.909) Colorectal cancer 18 77 0.973 (0.945-1.000) Pancreatic cancer 16 77 0.993 (0.981-1.000) Glioblastoma 10 77 0.923 (0.831-1.000) Men NSCLC 119 82 0.746 (0.677-0.815) Colorectal cancer 25 82 0.933 (0.884-0.982) Pancreatic cancer 22 82 0.993 (0.984-1.000) Glioblastoma 19 82 0.981 (0.959-1.000) All NSCLC 245 159 0.774 (0.728-0.820) Colorectal cancer 40 159 0.978 (0.961-0.996) Breast cancer 38 159 0.821 (0.736-0.906) Pancreatic cancer 35 159 0.987 (0.974-0.999) Glioblastoma 35 159 0.931 (0.890-0.972) Hepatobiliary carcinomas 14 159 0.991 (0.978-1.000)

Citation Format: Yue Gao, Chun-Jie Liu, Hua-Yi Li, Xiao-Ming Xiong, Sjors G.j.g. In ‘t Veld, Gui-Ling Li, Jia-Hao Liu, Guang-Yao Cai, Gui-Yan Xie, Shao-Qing Zeng, Yuan Wu, Jian-Hua Chi, Qiong Zhang, Xiao-Fei Jiao, Lin-Li Shi, Wan-Rong Lu, Wei-Guo Lv, Xing-Sheng Yang, Jurgen M.j. Piek, Cornelis D de Kroon, C.a.r. Lok, Anna Supernat, Sylwia Łapińska-Szumczyk, Anna Łojkowska, Anna J. Żaczek, Jacek Jassem, Bakhos A. Tannous, Nik Sol, Edward Post, Myron G. Best, Bei-Hua Kong, Xing Xie, Ding Ma, Thomas Wurdinger, An-Yuan Guo, Qing-Lei Gao. Platelet RNA signature enables early and accurate detection of ovarian cancer: An intercontinental, biomarker identification study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB168.

Benzophenone-3 breaches mouse Sertoli cell barrier and alters F-actin organization without evoking apoptosis

Benzophenone-3 (BP-3), one of the most commonly utilized ultraviolet filters in personal care products, has aroused public concern in recent years for its high chances of human exposure. Previous studies have found that BP-3 can impair testes development and spermatogenesis, but the targets of BP-3 are still unknown. In this study, primary Sertoli cells from 20-day-old mice were treated in vitro with 0-100 μM BP-3 for 24 h to identify its toxicity on Sertoli cells and Sertoli cell barrier. Results demonstrated that BP-3 could induce a notable change in cell morphology and impair Sertoli cell viability. The analysis of transepithelial electrical resistance showed that the integrity of the Sertoli cell barrier was destroyed by BP-3 (100 μM). Some structural proteins of the barrier including ZO-1, Occludin, and Connexin43 were lower expressed and the localization of basal ectoplasmic specializations protein β-catenin was altered because of BP-3 treatment. Further exploration suggested that BP-3 led to Sertoli cell F-actin disorganization by affecting the expression of Rictor, a key component of the mTORC2 complex. Moreover, although increased DNA damage marker γH2A.X was observed in the treatment group, the cell apoptosis rate was changeless which was further confirmed by increased BAX and stable Bcl-2 (two primary apoptosis regulating proteins). In conclusion, this study revealed that BP-3 had the potential to perturb the Sertoli cell barrier through altered junction proteins and disorganized F-actin, but it could hardly evoke Sertoli cell apoptosis.

Machine learning based early warning system enables accurate mortality risk prediction for COVID-19

Soaring cases of coronavirus disease (COVID-19) are pummeling the global health system. Overwhelmed health facilities have endeavored to mitigate the pandemic, but mortality of COVID-19 continues to increase. Here, we present a mortality risk prediction model for COVID-19 (MRPMC) that uses patients' clinical data on admission to stratify patients by mortality risk, which enables prediction of physiological deterioration and death up to 20 days in advance. This ensemble model is built using four machine learning methods including Logistic Regression, Support Vector Machine, Gradient Boosted Decision Tree, and Neural Network. We validate MRPMC in an internal validation cohort and two external validation cohorts, where it achieves an AUC of 0.9621 (95% CI: 0.9464-0.9778), 0.9760 (0.9613-0.9906), and 0.9246 (0.8763-0.9729), respectively. This model enables expeditious and accurate mortality risk stratification of patients with COVID-19, and potentially facilitates more responsive health systems that are conducive to high risk COVID-19 patients.

Isobutylparaben Negatively Affects Porcine Oocyte Maturation Through Increasing Oxidative Stress and Cytoskeletal Abnormalities

As a member of parabens (PBs), Isobutylparaben (IBP) has a broad-spectrum antimicrobial activity and widely used in personal care products and cosmetics. Recent studies have indicated that usage of IBP poses a potential threat to reproductive health. In this study, we aimed to reveal the effects of acute exposure to IBP on the meiotic maturation of porcine cumulus oocyte complexes. Initial study showed that 200 μM of IBP significantly reduced the rate of the first polar body extrusion with no significant effect on cumulus cell expansion; however, 400 μM of IBP could significantly affect both. Further research revealed that abnormal spindles, misalignment chromosomes, and aberrant distributed actin filaments were detected in IBP-treated oocytes, which indicates that the cytoskeleton architecture of oocyte could be the target of IBP. At the same time, ROS level and apoptosis rate of oocyte were significantly increased by IBP exposure. Moreover, the levels of H3K9me3 and H3K27me3 were significantly induced in oocytes by IBP. Collectively, these results demonstrate that acute exposure to IBP could disrupt porcine oocyte maturation through affecting cytoskeleton, oxidative stress, viability and epigenetic modification. Environ. Mol. Mutagen. 2020. © 2020 Wiley Periodicals, Inc.

WDR62 is a novel participator in spindle migration and asymmetric cytokinesis during mouse oocyte meiotic maturation

In female meiosis, oocyte meiotic maturation is a form of asymmetric cell division, producing the first polar body and a large oocyte, in which the asymmetry of oocyte meiotic division depends on spindle migration and positioning, and cortical polarization. In this study, we conclude that WDR62 (WD40-repeat protein 62) plays an important role in asymmetric meiotic division during mouse oocyte maturation. Our initial study demonstrated that WDR62 mainly co-localized with chromosomes during mouse oocyte meiotic maturation. Interference of Wdr62 by siRNA microinjection did not affect germinal vesicle breakdown (GVBD) but compromised the first polar body extrusion (PBE) with the large polar bodies generated, which is coupled with a higher incidence of spindle abnormality and chromosome misalignment. Further analysis concluded that loss of WDR62 blocked asymmetric spindle positioning and actin cap formation, which should be responsible for large polar body extrusion. Moreover, WDR62 decline intervened with the Arp2/3 complex, an upstream regulator for the cortical actin. Besides for p-MAPK, a critical regulator for the asymmetric division of oocyte, WDR62-depleted oocytes showed perturbation only in localization pattern but not expression level. In summary, our study defines WDR62 as an essential cytoskeletal regulator of spindle migration and asymmetric division during mouse oocyte meiotic maturation.

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.

Doxorubicin Exposure Affects Oocyte Meiotic Maturation through DNA Damage-Induced Meiotic Arrest

Developments in chemotherapeutics have enhanced the survival rate of cancer patients, however, adverse effects of chemotherapeutics on ovarian functions causes the fertility loss in young female cancer patients. Doxorubicin (DOX), as an anthracycline antitumor antibiotic, is extensively used to cure various malignancies. Recent studies have suggested that DOX can cause ovarian damage and affect the oocyte maturation, nevertheless the mechanism by which DOX on oocytes meiosis is poorly understood. In this study, we explored the mechanism for DOX-induced oocytes meiotic failure in vitro at human relevant exposure levels and time periods. Results described that DOX (100 nM) can interrupt the mouse oocytes meiotic maturation directly with reduced first polar body extrusion. Cell cycle analysis showed that most oocytes were arrested at metaphase I (MI) stage. However, DOX treatment had no effect on spindle structure but chromosomal misalignment. We observed that kinetochore-microtubule structure was affected and the spindle assemble checkpoint was provoked after DOX treatment. Moreover, severe DNA damage was found in DOX-treated oocytes indicated by the positive γ-H2A.X foci signal, which then may trigger oocytes early apoptosis. Besides, metaphase II oocytes with disorganized spindle morphologies and misaligned chromosomes were observed after DOX treatment. In conclusion, DOX have the potential to disrupt oocyte meiotic maturation through DNA damage induced meiotic arrest mediated by spindle assemble checkpoint activation. These findings can contribute to design the new therapies to alleviate DNA damage to preserve fertility for young female cancer patients with chemotherapeutics.

Effects of Acute Fluorene-9-Bisphenol Exposure on Mouse Oocyte in vitro Maturation and Its Possible Mechanisms

Fluorene-9-bisphenol (BHPF), a substitute of bisphenol A (BPA) used in the production of the so-called "BPA-free" plastics, has now been shown to be released from commercial plastic bottles into drinking water and has strong anti-estrogenic activity in mice, which suggests that BHPF is also an environmental toxin. However, whether BHPF exposure has effects on mouse oocyte development is unknown. In this study, the influence of acute exposure to BHPF (50-150 μM, 12 hr) on mouse oocyte maturation and its possible mechanisms were investigated. Of note, 50-μM BHPF had no effects on the maturation of mouse oocytes, whereas 100- and 150-μM BHPF significantly blocked germinal vesicle breakdown and led to the failure of first polar body extrusion. Particularly, 100-μM BHPF exposure severely decreased the cellular adenosine triphosphate in a time-dependent manner, which finally brought out the loss of spindles. In addition, the actin cytoskeleton was also impaired. The defective mitochondrial dynamics and decreased mitochondrial DNA implied the damage of mitochondria in BHPF-treated oocytes. Increased PINK1, Beclin1, and LC3B protein level and decreased TOMM20 and TOMM17A protein level illustrated that mitophagy was induced, which also confirmed that BHPF exposure impaired the cellular mitochondria. Moreover, BHPF induced reactive oxygen species accumulation and early apoptosis. Oocyte quality was also impaired by BHPF exposure through altering histone modifications evidenced by increased H3K9me3 and H3K27me3 levels. Collectively, our results indicated that BHPF exposure disrupted mouse oocyte maturation and reduced oocyte quality through affecting cytoskeleton architecture, mitochondrial function, oxidative stress, apoptosis, and histone modifications. Environ. Mol. Mutagen. 60:243-253, 2019. © 2018 Wiley Periodicals, Inc.

[Two cases report of laryngeal malignant melanoma and a review of literatures]

Summary Two patients both complained of one year history of hoarseness and the clinical manifestations and imageology among 2 patients were lack of specificity. The pathological tissue was successfully eradicated by surgical removal. Histopathology established laryngeal malignant melanoma as the diagnosis. The clinical manifestations and imageology were lack specificity between laryngeal malignant melanoma, laryngeal cancer and other malignant tumor, the diagnosis is difficult, often confirmed by postoperative pathology, the treatment is often by surgery and have a poor prognosis.

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.

SUMO2 modification of Aurora B and its impact on follicular development and atresia in the mouse ovary

In the mammalian ovary, >99% follicles fail to ovulate due to apoptosis in granulosa cells. Aurora B, a core subunit enzyme of the chromosomal passenger complex, exerts a crucial role in microtubule‑kinetochore attachment, and has been reported to be modified by small ubiquitin‑related modifier (SUMO) proteins. However, the details of how Aurora B and its SUMOylation impact on follicular development have yet to be fully elucidated. The aim of the present study was to explore the roles, and possible molecular mechanism, of Aurora B and its SUMOylation in the granulosa cells of the mouse follicle. It was revealed that the protein level of Aurora B increased with follicular development and the growth of the granulosa cells. Aurora B impacted follicular development and atresia through mediating the p38 mitogen‑activated protein kinase and FasL/Fas pathways, and caused the downregulation of cyclin‑dependent kinase 4, proliferating cell nuclear antigen, Bcl‑2, and upregulation of caspases‑3 and ‑8 to modulate the viability of the granulosa cells. In addition, Aurora B undergoes modification by SUMO2, but not by SUMO1, in vivo and in vitro, and Lys‑207 is a major modification site. SUMOylation modulates follicular development through an increase in Aurora B localization in the nucleus, and by stabilizing the protein level of Aurora B and keeping the viability of the granulosa cells. Taken together, Aurora B and its SUMOylation are important for follicular development and atresia in the ovaries of mice.

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.

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.

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.

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.

Genomic sequence, structural organization, molecular evolution, and aberrant rearrangement of promyelocytic leukemia zinc finger gene

The promyelocytic leukemia zinc finger gene (PLZF) is involved in chromosomal translocation t(11;17) associated with acute promyelocytic leukemia. In this work, a 201-kilobase genomic DNA region containing the entire PLZF gene was sequenced. Repeated elements account for 19.83%, and no obvious coding information other than PLZF is present over this region. PLZF contains six exons and five introns, and the exon organization corresponds well with protein domains. There are at least four alternative splicings (AS-I, -II, -III, and -IV) within exon 1. AS-I could be detected in most tissues tested whereas AS-II, -III, and -IV were present in the stomach, testis, and heart, respectively. Although splicing donor and acceptor signals at exon-intron boundaries for AS-I and exons 1-6 were classical (gt-ag), AS-II, -III, and -IV had atypical splicing sites. These alternative splicings, nevertheless, maintained the ORF and may encode isoforms with absence of important functional domains. In mRNA species without AS-I, there is a relatively long 5' UTR of 6.0 kilobases. A TATA box and several transcription factor binding sites were found in the putative promoter region upstream of the transcription start site. PLZF is a well conserved gene from Caenorhabditis elegans to human. PLZF paralogous sequences are found in human genome. The presence of two MLL/PLZF-like alignments on human chromosome 11q23 and 19 suggests a syntenic replication during evolution. The chromosomal breakpoints and joining sites in the index acute promyelocytic leukemia case with t(11;17) also were characterized, which suggests the involvement of DNA damage-repair mechanism.