Tex14, a Plk1-regulated protein, is required for kinetochore-microtubule attachment and regulation of the spindle assembly checkpoint

Unraveling the genetic basis of azoospermia: transcriptome profiling analyses in a Greek population

OBJECTIVE

To investigate whether idiopathic nonobstructive azoospermia (iNOA) has its own transcriptomic signature.

DESIGN

Testicular tissue biopsies were retrieved, processed, and prepared for ribonucleic acid (RNA) extraction from 26 consented patients diagnosed with iNOA. Samples were grouped into four pools based on the presence of testicular spermatozoa: two replicate pools for "No presence" (Null-spz-1 and Null-spz-2 pools), one for "High presence" (High-spz pool), and one for "Rare presence" (Rare-spz pool). A second set of replicate pools (CF-1 and CF-2) were used from patients with obstructive azoospermia (OA) and served as controls. RNA sequencing (RNA-seq) and comparative transcriptomics analysis were performed, followed by differential gene expression analysis focused on protein-coding genes only. Differentially expressed genes (DEGs) exclusively upregulated or downregulated were further analyzed using the Gene Ontology (GO), STRING, and Kyoto Encyclopedia of Genes and Genome bioinformatic platforms.

SUBJECTS

Males in whom iNOA was diagnosed.

EXPOSURE

Testicular biopsies from men in whom iNOA was diagnosed.

MAIN OUTCOME MEASURES

Protein-coding DEGs.

RESULTS

A significantly altered transcriptomic profile of protein-coding genes was identified in the testicular tissues from men with iNOA. A total of 3,858 genes exhibited dysregulated expression, with 1,994 genes being exclusively downregulated and 1,734 upregulated. Biological processes such as male gamete generation (GO:0048232) and meiotic cycle (GO:0051321) were significantly enriched by the downregulated DEGs whereas the upregulated DEGs enriched BPs such as regulation of cell death (GO:0010941), regulation of cell adhesion (GO:0030155), and defense response (GO:0006952). Interactome analysis identified hub genes among the downregulated DEGs, including PCNA, PLK1, MCM4, CDK1, CCNB1, AURKA, CCNA2, and CDC6, and among the upregulated DEGs, including EGFR, RELA, CTNNB1, MYC, JUN, SMAD3, STAT3 NFKB1, TGFB1, and ACTB. In addition, Kyoto Encyclopedia of Genes and Genome analysis demonstrated that pathways such as cell cycle (hsa04110) and oocyte meiosis (hsa04114) are primarily affected by the downregulated genes, whereas the upregulated genes mainly affected pathways such as the focal adhesion (hsa04510) and the PI3-Akt signaling pathway (hsa04151).

CONCLUSION

A distinct messenger RNA expression profile and altered transcriptomic activity were identified in the testicular tissues of men with iNOA.

CLINICAL TRIAL REGISTRATION NUMBER

University of Thessaly 1, 15.04.2016 and the Greek National Authority 701/15.9.2017.

Long-lived cytokinetic bridges coordinate sister-cell elimination in mouse embryos

Apoptosis is a key feature of preimplantation development, but whether it occurs in a cell-autonomous or coordinated manner was unknown. Here, we report that plasma membrane abscission, the final step of cell division, is profoundly delayed in early mouse embryos such that a cytokinetic bridge is maintained for the vast majority of the following interphase. Early embryos thus consist of many pairs of sister cells connected by stable cytokinetic bridges that allow them to share diffusible molecules. We show that apoptotic regulators are shared through cytokinetic bridges and that these bridges ensure that if one cell enters apoptosis, its sister cell does as well. Long-lived cytokinetic bridges are thus a previously unappreciated form of cell-cell communication within the mouse embryo that coordinate the clearance of pairs of cells with similar developmental histories.

YY1 drives PARP1 expression essential for PARylation of NONO in mRNA maturation during neuroblastoma progression

BACKGROUND

Neuroblastoma (NB), the most prevalent solid tumor in children, arises from sympathetic nervous system and accounts for 15% of pediatric cancer mortality. This malignancy exhibits substantial genetic and clinical heterogeneity, thus complicating treatment strategies. Poly(ADP-ribose) polymerase 1 (PARP1), a key enzyme catalyzing polyADP-ribosylation (PARylation), plays critical roles in various cellular processes, and contributes to tumorigenesis and aggressiveness. However, the functions and regulatory mechanisms of PARP1 in NB progression still remain to be determined.

METHODS

The association of PARP1 expression with NB patients' survival was analyzed by mining of R2 database. Western blotting, reverse transcription-polymerase chain reaction, MTT colorimetric, soft agar, and matrigel invasion assays were utilized to assess PARP1 expression and its effects on aggressiveness of NB cell lines. Chromatin immunoprecipitation (ChIP) sequencing and ChIP assays were employed to investigate the binding of Yin Yang 1 (YY1) to PARP1 promoter. Protein interactions were explored by BioGRID database analysis, molecular docking, and co-immunoprecipitation assay. RNA sequencing and crosslinking-immunoprecipitation high throughput sequencing datasets were used to identify precursor mRNA splicing targets of non-POU domain containing octamer binding protein (NONO).

RESULTS

High PARP1 expression was associated with poor survival of NB patients. PARP1 over-expression enhanced the proliferation and invasion of NB cell lines, confirming its oncogenic roles. YY1 was identified as a key transcriptional regulator facilitating PARP1 expression. Additionally, PARP1 interacted with NONO to induce its PARylation, resulting in stabilization of NONO protein via preventing ubiquitin-mediated degradation. NONO facilitated the splicing and mRNA maturation of target genes a disintegrin and metalloproteinase domain 8 (ADAM8) and testis-expressed gene 14 (TEX14) in a PARylation-dependent manner. Rescue experiments indicated that YY1 facilitated PARP1-mediated PARylation of NONO and subsequent mRNA maturation of ADAM8 and TEX14 in NB cells. In clinical NB cases, high expression of YY1, PARP1, NONO, ADAM8, or TEX14 was associated with poor survival of patients.

CONCLUSIONS

These findings indicate that YY1 drives PARP1 expression essential for PARylation of NONO in mRNA maturation during NB progression.

Correlation between TEX14 and ADAM17 expressions in colorectal cancer tissues of elderly patients and neoplasm staging, invasion, and metastasis

BACKGROUND

Colorectal cancer (CRC) is one of the most frequently encountered malignant tumors in clinical settings. Proteins encoded by the testis-expressed gene 14 (TEX14) are imperative for spermatogenesis, necessitating intercellular bridges between germ cells. Anomalous expression of TEX14 has also been associated with the proliferation and differentiation of certain tumor cells. Recombinant A disintegrin and metalloprotease 17 (ADAM17) is known as a membrane-bound protease that regulates cellular activities and signal transduction by hydrolyzing various substrate proteins on the cell membrane. We hypothesize that TEX14 and ADAM17 may serve as potential biomarkers influencing the staging, invasion, and metastasis of CRC.

AIM

To probe the correlation between TEX17 and ADAM17 profiles in the CRC tissues of elderly patients and their association with CRC staging, invasion, and metastasis.

METHODS

We gathered data from 86 elderly patients diagnosed pathologically with CRC between April 2020 and December 2023. For each patient, one sample of cancer tissue and one sample of adjacent normal tissue were harvested. Real-time fluorescence quantitative PCR measured the mRNA profiles of TEX14 and ADAM17. Immunohistochemistry ascertained the positivity rates of TEX14 and ADAM17 expressions. Clinical pathological features of neoplasm staging, invasion, and metastasis were collected, and the association between TEX14 and ADAM17 expressions and clinical pathology was evaluated.

RESULTS

The mRNA and expression profiles of TEX14 and ADAM17 were significantly elevated in CRC tissues. The positivity rates of TEX14 and ADAM17 proteins in CRC tissues were 70.93% and 77.91%, respectively. There were no significant differences in age, sex, pathological type, and tumor diameter between TEX14 and ADAM17-positive and -negative patients. Patients with higher tumor differentiation degree, deeper infiltration and TNM stages ranging from III to IV exhibited higher positivity rates of TEX14 and ADAM17. Patients with lymph node metastasis and distant metastasis showed higher positivity rates of TEX14 and ADAM17 than those without. Positive expressions of TEX14 and ADAM17 were highly correlated with tumor staging, invasion, and metastasis.

CONCLUSION

TEX14 and ADAM17 profiles were significantly elevated in the CRC tissues of elderly patients, and their high expressions were associated with tumor staging, invasion, and metastasis.

Low androgen signaling rescues genome integrity with innate immune response by reducing fertility in humans

Development of the gonads under complex androgen regulation is critical for germ cells specification. In this work we addressed the relationship between androgens and genomic integrity determining human fertility. We used different study groups: individuals with Differences of Sex Development (DSD), including Complete Androgen Insensitivity Syndrome (CAIS) due to mutated androgen receptor (AR), and men with idiopathic nonobstructive azoospermia. Both showed genome integrity status influenced by androgen signaling via innate immune response activation in blood and gonads. Whole proteome analysis connected low AR to interleukin-specific gene expression, while compromised genome stability and tumorigenesis were also supported by interferons. AR expression was associated with predominant DNA damage phenotype, that eliminated AR-positive Sertoli cells as the degeneration of gonads increased. Low AR contributed to resistance from the inhibition of DNA repair in primary leukocytes. Downregulation of androgen promoted apoptosis and specific innate immune response with higher susceptibility in cells carrying genomic instability.

Peripheral Blood Mononuclear Cell derived Biomarker detection using eXplainable Artificial Intelligence (XAI) provides better diagnosis of Breast Cancer

The incidence and mortality rate of breast cancer increases yearly by an average of 1.44 % and 0.23 %, respectively. Till 2021, there were 7.8 million women who had been diagnosed with breast cancer within 5 years. Biopsies of tumors are often expensive and invasive and raise the risk of serious complications like infection, excessive bleeding, and puncture damage to nearby tissues and organs. Early detection biomarkers are often variably expressed in different patients and may even be below the detection level at an early stage. Hence PBMC that shows alteration in gene profile as a result of interaction with tumor antigens may serve as a better early detection biomarker. Also, such alterations in immune gene profile in PBMCs are more prone to detection despite variability in different breast cancer mutants.This study aimed to identify potential diagnostic biomarkers for breast cancer using eXplainable Artificial Intelligence (XAI) on XGBoost machine learning (ML) models trained on a binary classification dataset containing the expression data of PBMCs from 252 breast cancer patients and 194 healthy women.After effectively adding SHAP values further into the XGBoost model, ten important genes related to breast cancer development were discovered to be effective potential biomarkers. Our studies showed that SVIP, BEND3, MDGA2, LEF1-AS1, PRM1, TEX14, MZB1, TMIGD2, KIT, and FKBP7 are key genes that impact model prediction. These genes may serve as early, non-invasive diagnostic and prognostic biomarkers for breast cancer patients.

Biology of Cancer-Testis Antigens and Their Therapeutic Implications in Cancer

Tumour-specific antigens have been an area of interest in cancer therapy since their discovery in the middle of the 20th century. In the era of immune-based cancer therapeutics, redirecting our immune cells to target these tumour-specific antigens has become even more relevant. Cancer-testis antigens (CTAs) are a class of antigens with an expression specific to the testis and cancer cells. CTAs have also been demonstrated to be expressed in a wide variety of cancers. Due to their frequency and specificity of expression in a multitude of cancers, CTAs have been particularly attractive as cancer-specific therapeutic targets. There is now a rapid expansion of CTAs being identified and many studies have been conducted to correlate CTA expression with cancer and therapy-resistant phenotypes. Furthermore, there is an increasing number of clinical trials involving using some of these CTAs as molecular targets in pharmacological and immune-targeted therapeutics for various cancers. This review will summarise the current knowledge of the biology of known CTAs in tumorigenesis and the regulation of CTA genes. CTAs as molecular targets and the therapeutic implications of these CTA-targeted anticancer strategies will also be discussed.

Polo-like kinase 1 is related with malignant characteristics and inhibits macrophages infiltration in glioma

BACKGROUND

Tumor immune microenvironment (TIM) plays a critical role in tumorigenesis and progression. Recently, therapies based on modulating TIM have made great breakthroughs in cancer treatment. Polo-like kinase 1 (PLK1) is a crucial regulatory factor of the cell cycle process and its dysregulations often cause various pathological processes including tumorigenesis. However, the detailed mechanisms surrounding the regulation of PLK1 on glioma immune microenvironment remain undefined.

METHODS

Public databases and online datasets were used to extract data of PLK1 expression, clinical features, genetic alterations, and biological functions. The EdU, flow cytometry, and macrophage infiltration assays as well as xenograft animal experiments were performed to determine the relationship between PLK1 and glioma immune microenvironment in vivo and in vitro.

RESULTS

PLK1 is always highly expressed in multiple cancers especially in glioma. Univariable and Multivariate proportional hazard Cox analysis showed that PLK1 was a prognostic biomarker for glioma. Simultaneously, highly expressed PLK1 is significantly related to prognosis, histological and genetic features in glioma by analyzing public databases. In addition, the enrichment analysis suggested that PLK1 might related to "immune response", "cell cycle", "DNA replication", and "mismatch repair" in glioma. Immune infiltration analysis demonstrated that highly expressed PLK1 inhibited M1 macrophages infiltration to glioblastoma immune microenvironment by Quantiseq and Xcell databases and negatively related to some chemokines and marker genes of M1 macrophages in glioblastoma. Subsequent experiments confirmed that PLK1 knockdown inhibited the proliferation of glioma cells but increased the M1 macrophages infiltration and polarization. Furthermore, in glioma xenograft mouse models, we showed that inhibiting PLK1 blocked tumor proliferation and increased the M1 macrophages infiltration. Finally, PLK1 methylation analysis and lncRNA-miRNA network revealed the potential mechanism of abnormal PLK1 expression in glioma.

CONCLUSIONS

PLK1 inhibits M1 macrophages infiltration into glioma immune microenvironment and is a potential biomarker for glioma.

Establishment and Evaluation of Dual HDAC/BET Inhibitors as Therapeutic Options for Germ Cell Tumors and Other Urological Malignancies

Urological malignancies represent major challenges for clinicians, with annually rising incidences. In addition, cisplatin treatment induced long-term toxicities and the development of therapy resistance emphasize the need for novel therapeutics. In this study, we analyzed the effects of novel histone deacetylase (HDAC) and bromodomain and extraterminal domain-containing (BET) inhibitors to combine them into a potent HDAC-BET-fusion molecule and to understand their molecular mode-of-action. Treatment of (cisplatin-resistant) germ cell tumors (GCT), urothelial, renal, and prostate carcinoma cells with the HDAC, BET, and dual inhibitors decreased cell viability, induced apoptosis, and affected the cell cycle. Furthermore, a dual inhibitor considerably decreased tumor burden in GCT xenograft models. On a molecular level, correlating RNA- to ATAC-sequencing data indicated a considerable induction of gene expression, accompanied by site-specific changes of chromatin accessibility after HDAC inhibitor application. Upregulated genes could be linked to intra- and extra-cellular trafficking, cellular organization, and neuronal processes, including neuroendocrine differentiation. Regarding chromatin accessibility on a global level, an equal distribution of active or repressed DNA accessibility has been detected after HDAC inhibitor treatment, questioning the current understanding of HDAC inhibitor function. In summary, our HDAC, BET, and dual inhibitors represent a new treatment alternative for urological malignancies. Furthermore, we shed light on new molecular and epigenetic mechanisms of the tested epi-drugs, allowing for a better understanding of the underlying modes-of-action and risk assessment for the patient.

Understanding the Underlying Molecular Mechanisms of Meiotic Arrest during In Vitro Spermatogenesis in Rat Prepubertal Testicular Tissue

In vitro spermatogenesis appears to be a promising approach to restore the fertility of childhood cancer survivors. The rat model has proven to be challenging, since germ cell maturation is arrested in organotypic cultures. Here, we report that, despite a meiotic entry, abnormal synaptonemal complexes were found in spermatocytes, and in vitro matured rat prepubertal testicular tissues displayed an immature phenotype. RNA-sequencing analyses highlighted up to 600 differentially expressed genes between in vitro and in vivo conditions, including genes involved in blood-testis barrier (BTB) formation and steroidogenesis. BTB integrity, the expression of two steroidogenic enzymes, and androgen receptors were indeed altered in vitro. Moreover, most of the top 10 predicted upstream regulators of deregulated genes were involved in inflammatory processes or immune cell recruitment. However, none of the three anti-inflammatory molecules tested in this study promoted meiotic progression. By analysing for the first time in vitro matured rat prepubertal testicular tissues at the molecular level, we uncovered the deregulation of several genes and revealed that defective BTB function, altered steroidogenic pathway, and probably inflammation, could be at the origin of meiotic arrest.

Mediterranean Diet as a Shield against Male Infertility and Cancer Risk Induced by Environmental Pollutants: A Focus on Flavonoids

The role of environmental factors in influencing health status is well documented. Heavy metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, dioxins, pesticides, ultrafine particles, produced by human activities put a strain on the body’s entire defense system. Therefore, together with public health measures, evidence-based individual resilience measures are necessary to mitigate cancer risk under environmental stress and to prevent reproductive dysfunction and non-communicable diseases; this is especially relevant for workers occupationally exposed to pollutants and/or populations residing in highly polluted areas. The Mediterranean diet is characterized by a high intake of fruits and vegetables rich in flavonoids, that can promote the elimination of pollutants in tissues and fluids and/or mitigate their effects through different mechanisms. In this review, we collected evidence from pre-clinical and clinical studies showing that the impairment of male fertility and gonadal development, as well as cancers of reproductive system, due to the exposure of organic and inorganic pollutants, may be counteracted by flavonoids.

Hypomethylation-activated cancer-testis gene LIN28B promotes cell proliferation and metastasis in gastric cancer

BACKGROUND

Previous studies have revealed the significance of several cancer/testis (CT) genes in gastric cancer (GC). Here, we identified candidate CT oncogenes in GC, which were activated by the promoter (p) hypomethylation.

METHODS

Transcriptome profiling and DNA methylation data of stomach adenocarcinoma (STAD) were downloaded from The Cancer Genome Atlas (TCGA) database. We applied multiple Cox regression analysis to identify survival-related CT genes. CpG sites associated with hypomethylated activation were defined by Spearman's rank correlation analysis. We used the CRISPR/dCas9 technique to accurately mediate p hypomethylation in a GC cell line (HGC27) and verify the effect of targeted CpG sites on gene expression. Finally, we verified the function via gain- and loss-of-function assays in vitro.

RESULTS

We recognized LIN28B as a highly activated CT gene in GC, whose high expression was associated with poor prognosis of GC patients [hazard ratio (HR) = 1.90, 95 %CI:1.26-2.87, P = 2.14 × 10^-3]. Bioinformatics analysis found that hypomethylation of four CpG sites at LIN28B p were negatively correlated with its elevated expression, and we verified that p hypomethylation could activate LIN28B expression via accurately mediated p methylation. Moreover, knockout of LIN28B markedly repressed proliferation, metastasis, and invasion of GC cells in vitro. In contrast, LIN28B over-expression could promote metastasis and invasion of GC cells.

CONCLUSION

In summary, we found that CT gene LIN28B could be activated by p hypomethylation in GC, which suggested that hypomethylation of specific CpG sites could be a potential molecular marker for prognosis prediction and individualized treatment among GC patients.

Testis transcriptome profiling identified lncRNAs involved in spermatogenic arrest of cattleyak

Cattleyaks are the crossbred offspring between cattle and yaks, exhibiting the prominent adaptability to the harsh environment as yaks and much higher growth performances than yaks around Qinghai-Tibet plateau. Unfortunately, cattleyak cannot be effectively used in yak breeding due to its male infertility resulted from spermatogenic arrest. In this study, we performed RNA sequencing (RNA-seq) and bioinformatics analysis to determine the expression profiles of long noncoding RNA (lncRNA) from cattleyak and yak testis. A total of 604 differentially expressed (DE) lncRNAs (135 upregulated and 469 downregulated) were identified in cattleyak with respect to yak. Through gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, we identified several DE lncRNAs regulating the mitotic cell cycle processes by targeting the genes significantly associated with the mitotic cell cycle checkpoint and DNA damage checkpoint term and also significantly involved in p53 signaling pathway, mismatch repair and homologous recombination pathway (P < 0.05). The reverse transcription PCR (RT-PCR) and quantitative Real-Time PCR (qRT-PCR) analysis of the randomly selected fourteen DE lncRNAs and the seven target genes validated the RNA-seq data and their true expressions during spermatogenesis in vivo. Molecular cloning and sequencing indicated that the testis lncRNAs NONBTAT012170 and NONBTAT010258 presented higher similarity among different cattleyak and yak individuals. The downregulation of these target genes in cattleyak contributed to the abnormal DNA replication and spermatogenic arrest during the S phase of mitotic cell cycle. This study provided a novel insight into lncRNA expression profile changes associated with spermatogenic arrest of cattleyak.

Microtubule Cytoskeleton and Spermatogenesis-Lesson From Studies of Toxicant Models

Studies have shown that mammalian testes, in particular the Sertoli cells, are highly susceptible to exposure of environmental toxicants, such as cadmium, perfluorooctanesulfonate, phthalates, 2,5-hexanedione and bisphenol A. However, important studies conducted by reproductive toxicologists and/or biologists in the past have been treated as toxicology reports per se. Yet, many of these studies provided important mechanistic insights on the toxicant-induced testis injury and reproductive dysfunction, relevant to the biology of the testis and spermatogenesis. Furthermore, recent studies have shown that findings obtained from toxicant models are exceedingly helpful tools to unravel the biology of testis function in particular spermatogenesis, including specific cellular events associated with spermatid transport to support spermiogenesis and spermiation. In this review, we critically evaluate some recent data, focusing primarily on the molecular structure and role of microtubules in cellular function, illustrating the importance of toxicant models to unravel the biology of microtubule cytoskeleton in supporting spermatogenesis, well beyond information on toxicology. These findings have opened up some potential areas of research which should be carefully evaluated in the years to come.

Impact of genetic polymorphisms in kinetochore and spindle assembly genes on chromosomal aberration frequency in healthy humans

Genomic instability is a characteristic of a majority of human malignancies. Chromosomal instability is a common form of genomic instability that can be caused by defects in mitotic checkpoint genes. Chromosomal aberrations in peripheral blood are also indicative of genotoxic exposure and potential cancer risk. We evaluated associations between inherited genetic variants in 33 mitotic checkpoint genes and the frequency of chromosomal aberrations (CAs) in the presence and absence of environmental genotoxic exposure. Associations with both chromosome and chromatid type of aberrations were evaluated in two cohorts of healthy individuals, namely an exposed and a reference group consisting of 607 and 866 individuals, respectively. Binary logistic and linear regression analyses were performed for the association studies. Bonferroni-corrected significant p-value was 5 × 10-4 for 99 tests based on the number of analyzed genes and phenotypes. In the reference group the most prominent associations were found with variants in CCNB1, a master regulator of mitosis, and in genes involved in kinetochore function, including CENPH and TEX14, whereas in the exposed group the main association was found with variants in TTK, also an important gene in kinetochore function. How the identified variants may affect the fidelity of mitotic checkpoint remains to be investigated, however, the present study suggests that genetic variation may partly explain interindividual variation in the formation of CAs.

MCF7 Spheroid Development: New Insight about Spatio/Temporal Arrangements of TNTs, Amyloid Fibrils, Cell Connections, and Cellular Bridges

Human breast adenocarcinoma cells (MCF7) grow in three-dimensional culture as spheroids that represent the structural complexity of avascular tumors. Therefore, spheroids offer a powerful tool for studying cancer development, aggressiveness, and drug resistance. Notwithstanding the large amount of data regarding the formation of MCF7 spheroids, a detailed description of the morpho-functional changes during their aggregation and maturation is still lacking. In this study, in addition to the already established role of gap junctions, we show evidence of tunneling nanotube (TNT) formation, amyloid fibril production, and opening of large stable cellular bridges, thus reporting the sequential events leading to MCF7 spheroid formation. The variation in cell phenotypes, sustained by dynamic expression of multiple proteins, leads to complex networking among cells similar to the sequence of morphogenetic steps occurring in embryogenesis/organogenesis. On the basis of the observation that early events in spheroid formation are strictly linked to the redox homeostasis, which in turn regulate amyloidogenesis, we show that the administration of N-acetyl-l-cysteine (NAC), a reactive oxygen species (ROS) scavenger that reduces the capability of cells to produce amyloid fibrils, significantly affects their ability to aggregate. Moreover, cells aggregation events, which exploit the intrinsic adhesiveness of amyloid fibrils, significantly decrease following the administration during the early aggregation phase of neutral endopeptidase (NEP), an amyloid degrading enzyme.

Recurrent Mutations in APC and CTNNB1 and Activated Wnt/β-catenin Signaling in Intraductal Papillary Neoplasms of the Bile Duct: A Whole Exome Sequencing Study

This study aimed to elucidate the genetic landscape of biliary papillary neoplasms. Of 28 cases examined, 7 underwent whole exome sequencing, while the remaining 21 were used for validation studies with targeted sequencing. In the whole exome sequencing study, 4/7 cases had mutations in either APC or CTNNB1, both of which belong to the Wnt/β-catenin pathway. Somatic mutations were also identified in genes involved in RAS signaling (KRAS, BRAF), a cell cycle regulator (CDC27), histone methyltransferase (KMT2C, KMT2D), and DNA mismatch repair (MSH3, MSH6, PMS1). Combined with discovery and validation cohorts, mutations in APC or CTNNB1 were observed in 6/28 subjects (21%) and were mutually exclusive. When the cases were classified into intraductal papillary neoplasms of the bile duct (IPNBs, n=14) and papillary cholangiocarcinomas (n=14) based on the recently proposed classification criteria, mutations in APC and CTNNB1 appeared to be entirely restricted to IPNBs with 6/14 cases (43%) harboring mutations in either gene. These genetic alterations were detected across the 3 nonintestinal histologic types. In immunohistochemistry, the aberrant cytoplasmic and/or nuclear expression of β-catenin was found in not only 5/6 IPNBs with APC or CTNNB1 mutations, but also 6/8 cases with wild-type APC and CTNNB1 (total 79%). In addition, APC and CTNNB1 alterations were exceptional in nonpapillary cholangiocarcinomas (n=29) with a single case harboring CTNNB1 mutation (3%). This study demonstrated recurrent mutations in APC and CTNNB1 in nonintestinal-type IPNBs, suggesting that activation of the Wnt/β-catenin signaling pathway is relevant to the development and progression of IPNBs.

Testicular Cancer: Genes, Environment, Hormones

Testicular cancer (TC) represents one of the most peculiar clinical challenges at present. In fact, currently treatments are so effective ensuring a 5 years disease-free survival rate in nearly 95% of patients. On the other hand however, TC represents the most frequent newly diagnosed form of cancer in men between the ages of 14 and 44 years, with an incidence ranging from <1 to 9.9 affected individuals per 100,000 males across countries, while the overall incidence is also increasing worldwide. Furthermore, cancer survivors show a 2% risk of developing cancer in the contralateral testis within 15 years of initial diagnosis. This complex and multifaceted scenario requires a great deal of effort to understand the clinical base of available evidence. It is now clear that genetic, environmental and hormonal risk factors concur and mutually influence both the development of the disease and its prognosis, in terms of response to treatment and the risk of recurrence. In this paper, the most recent issues describing the relative contribution of the aforementioned risk factors in TC development are discussed. In addition, particular attention is paid to the exposure to environmental chemical substances and thermal stress, whose role in cancer development and progression has recently been investigated at the molecular level.

Genetic mechanisms underlying spermatic and testicular traits within and among cattle breeds: systematic review and prioritization of GWAS results

Reduced bull fertility imposes economic losses in bovine herds. Specifically, testicular and spermatic traits are important indicators of reproductive efficiency. Several genome-wide association studies (GWAS) have identified genomic regions associated with these fertility traits. The aims of this study were as follows: 1) to perform a systematic review of GWAS results for spermatic and testicular traits in cattle and 2) to identify key functional candidate genes for these traits. The identification of functional candidate genes was performed using a systems biology approach, where genes shared between traits and studies were evaluated by a guilt by association gene prioritization (GUILDify and ToppGene software) in order to identify the best functional candidates. These candidate genes were integrated and analyzed in order to identify overlapping patterns among traits and breeds. Results showed that GWAS for testicular-related traits have been developed for beef breeds only, whereas the majority of GWAS for spermatic-related traits were conducted using dairy breeds. When comparing traits measured within the same study, the highest number of genes shared between different traits was observed, indicating a high impact of the population genetic structure and environmental effects. Several chromosomal regions were enriched for functional candidate genes associated with fertility traits. Moreover, multiple functional candidate genes were enriched for markers in a species-specific basis, taurine (Bos taurus) or indicine (Bos indicus). For the different candidate regions identified in the GWAS in the literature, functional candidate genes were detected as follows: B. Taurus chromosome X (BTX) (TEX11, IRAK, CDK16, ATP7A, ATRX, HDAC6, FMR1, L1CAM, MECP2, etc.), BTA17 (TRPV4 and DYNLL1), and BTA14 (MOS, FABP5, ZFPM2). These genes are responsible for regulating important metabolic pathways or biological processes associated with fertility, such as progression of spermatogenesis, control of ciliary activity, development of Sertoli cells, DNA integrity in spermatozoa, and homeostasis of testicular cells. This study represents the first systematic review on male fertility traits in cattle using a system biology approach to identify key candidate genes for these traits.

Emerging Contributions of Cancer/Testis Antigens to Neoplastic Behaviors

Tumors of nearly every origin activate the expression of genes normally restricted to gametogenic cells. These genes encode proteins termed cancer/testis (CT) antigens, since expression outside of their naturally immune-privileged site can evoke an immune response. Despite extensive efforts to exploit CT antigens as immunotherapeutic targets, investigation of whether these proteins participate in tumorigenic processes has lagged. Here, we discuss emerging evidence that demonstrates that CT antigens can confer a selective advantage to tumor cells by promoting oncogenic processes or permitting evasion of tumor-suppressive mechanisms. These advances indicate the inherent flexibility of tumor cell regulatory networks to engage aberrantly expressed proteins to promote neoplastic behaviors, which could ultimately present novel therapeutic entry points.

Polo-like kinase 1 inhibition results in misaligned chromosomes and aberrant spindles in porcine oocytes during the first meiotic division

Polo-like kinase 1 (Plk1), a type of serine/threonine protein kinase, has been implicated in various functions in the regulation of mitotic processes. However, these kinase's roles in meiotic division are not fully understood, particularly in the meiotic maturation of porcine oocytes. In this study, the expression and spatiotemporal localization of Plk1 were initially assessed in the meiotic process of pig oocytes by utilizing Western blotting with immunofluorescent staining combined with confocal microscopy imaging technique. The results showed that Plk1 was expressed and exhibited a dynamic subcellular localization throughout the meiotic process. After germinal vesicle breakdown (GVBD), Plk1 was detected prominently around the condensed chromosomes and subsequently exhibited a similar subcellular localization to α-tubulin throughout subsequent meiotic phases, with particular enrichment being observed near spindle poles at MI and MII. Inhibition of Plk1 via a highly selective inhibitor, GSK461364, led to the failure of first polar body extrusion in porcine oocytes, with the majority of the treated oocytes being arrested in GVBD. Further subcellular structure examination results indicated that Plk1 inhibition caused the great majority of oocytes with spindle abnormalities and chromosome misalignment during the first meiotic division. The results of this study illustrate that Plk1 is critical for the first meiotic division in porcine oocytes through its influence on spindle organization and chromosome alignment, which further affects the ensuing meiotic cell cycle progression.

Loss of PFKFB4 induces cell death in mitotically arrested ovarian cancer cells

Taxanes represent some of the most commonly used chemotherapeutic agents for ovarian cancer treatment. However, they are only effective in approximately 40% of patients. Novel therapeutic strategies are required to potentiate their effect and improve patient outcome. A hallmark of many cancers is the constitutive activation of the PI3K/AKT pathway, which drives cell survival and metabolism. We discovered a striking decrease in AKT activity coupled with a significant reduction in glucose 6-phosphate and ATP levels during mitotic arrest in the majority of ovarian cancer cell lines tested, indicating a potential metabolic vulnerability. A high-content siRNA screen to detect novel metabolic targets in mitotically arrested ovarian cancer cells identified the glycolytic enzyme PFKFB4. PFKFB4 depletion increased caspase 3/7 activity, and levels of reactive oxygen species only in mitotically arrested cells, and significantly enhanced mitotic cell death after paclitaxel treatment. Depletion of PFKFB3 demonstrated a similar phenotype. The observation that some ovarian cancer cells lose AKT activity during mitotic arrest and become vulnerable to metabolic targeting is a new concept in cancer therapy. Thus, combining mitotic-targeted therapies with glycolytic inhibitors may act to potentiate the effects of antimitotics in ovarian cancer through mitosis-specific cell death.

The secret life of kinases: insights into non-catalytic signalling functions from pseudokinases

Over the past decade, our understanding of the mechanisms by which pseudokinases, which comprise ∼10% of the human and mouse kinomes, mediate signal transduction has advanced rapidly with increasing structural, biochemical, cellular and genetic studies. Pseudokinases are the catalytically defective counterparts of conventional, active protein kinases and have been attributed functions as protein interaction domains acting variously as allosteric modulators of conventional protein kinases and other enzymes, as regulators of protein trafficking or localisation, as hubs to nucleate assembly of signalling complexes, and as transmembrane effectors of such functions. Here, by categorising mammalian pseudokinases based on their known functions, we illustrate the mechanistic diversity among these proteins, which can be viewed as a window into understanding the non-catalytic functions that can be exerted by conventional protein kinases.

Identification of 19 new risk loci and potential regulatory mechanisms influencing susceptibility to testicular germ cell tumor

Genome-wide association studies (GWAS) have transformed understanding of susceptibility to testicular germ cell tumors (TGCTs), but much of the heritability remains unexplained. Here we report a new GWAS, a meta-analysis with previous GWAS and a replication series, totaling 7,319 TGCT cases and 23,082 controls. We identify 19 new TGCT risk loci, roughly doubling the number of known TGCT risk loci to 44. By performing in situ Hi-C in TGCT cells, we provide evidence for a network of physical interactions among all 44 TGCT risk SNPs and candidate causal genes. Our findings implicate widespread disruption of developmental transcriptional regulators as a basis of TGCT susceptibility, consistent with failed primordial germ cell differentiation as an initiating step in oncogenesis. Defective microtubule assembly and dysregulation of KIT-MAPK signaling also feature as recurrently disrupted pathways. Our findings support a polygenic model of risk and provide insight into the biological basis of TGCT.

The equilibrium of ubiquitination and deubiquitination at PLK1 regulates sister chromatid separation

PLK1 regulates almost every aspect of mitotic events, including mitotic entry, spindle assembly, chromosome alignment, sister chromatid segregation, metaphase-anaphase transition, cytokinesis, etc. In regulating the chromosome alignment and sister chromatid segregation, PLK1 has to be localized to and removed from kinetochores at the right times, and the underlying mechanism that regulates PLK1 both spatially and temporally only became clearer recently. It has been found that deubiquitination and ubiquitination of PLK1 are responsible for its localization to and dissociation from the kinetochores, respectively. The equilibrium of this ubiquitination and deubiquitination plays an important role in regulating proper chromosome alignment and timely sister chromatid segregation. Here, we summarize and discuss the recent findings in investigating the spatial and temporal regulation of PLK1 during chromosome alignment and sister chromatid segregation.

Molecular Regulation of the Spindle Assembly Checkpoint by Kinases and Phosphatases

The spindle assembly checkpoint (SAC) is a surveillance mechanism contributing to the preservation of genomic stability by monitoring the microtubule attachment to, and/or the tension status of, each kinetochore during mitosis. The SAC halts metaphase to anaphase transition in the presence of unattached and/or untensed kinetochore(s) by releasing the mitotic checkpoint complex (MCC) from these improperly-oriented kinetochores to inhibit the anaphase-promoting complex/cyclosome (APC/C). The reversible phosphorylation of a variety of substrates at the kinetochore by antagonistic kinases and phosphatases is one major signaling mechanism for promptly turning on or turning off the SAC. In such a complex network, some kinases act at the apex of the SAC cascade by either generating (monopolar spindle 1, MPS1/TTK and likely polo-like kinase 1, PLK1), or contributing to generate (Aurora kinase B) kinetochore phospho-docking sites for the hierarchical recruitment of the SAC proteins. Aurora kinase B, MPS1 and budding uninhibited by benzimidazoles 1 (BUB1) also promote sister chromatid biorientation by modulating kinetochore microtubule stability. Moreover, MPS1, BUB1, and PLK1 seem to play key roles in APC/C inhibition by mechanisms dependent and/or independent on MCC assembly. The protein phosphatase 1 and 2A (PP1 and PP2A) are recruited to kinetochores to oppose kinase activity. These phosphatases reverse the phosphorylation of kinetochore targets promoting the microtubule attachment stabilization, sister kinetochore biorientation and SAC silencing. The kinase-phosphatase network is crucial as it renders the SAC a dynamic, graded-signaling, high responsive, and robust process thereby ensuring timely anaphase onset and preventing the generation of proneoplastic aneuploidy.

Genetic changes associated with testicular cancer susceptibility

Testicular germ cell tumor (TGCT) is a highly heritable cancer primarily affecting young white men. Genome-wide association studies (GWAS) have been particularly effective in identifying multiple common variants with strong contribution to TGCT risk. These loci identified through association studies have implicated multiple genes as associated with TGCT predisposition, many of which are unique among cancer types, and regulate processes such as pluripotency, sex specification, and microtubule assembly. Together these biologically plausible genes converge on pathways involved in male germ cell development and maturation, and suggest that perturbation of them confers susceptibility to TGCT, as a developmental defect of germ cell differentiation.

Defining the Schistosoma haematobium kinome enables the prediction of essential kinases as anti-schistosome drug targets

The blood fluke Schistosoma haematobium causes urogenital schistosomiasis, a neglected tropical disease (NTD) that affects more than 110 million people. Treating this disease by targeted or mass administration with a single chemical, praziquantel, carries the risk that drug resistance will develop in this pathogen. Therefore, there is an imperative to search for new drug targets in S. haematobium and other schistosomes. In this regard, protein kinases have potential, given their essential roles in biological processes and as targets for drugs already approved by the US Food and Drug Administration (FDA) for use in humans. In this context, we defined here the kinome of S. haematobium using a refined bioinformatic pipeline. We classified, curated and annotated predicted kinases, and assessed the developmental transcription profiles of kinase genes. Then, we prioritised a panel of kinases as potential drug targets and inferred chemicals that bind to them using an integrated bioinformatic pipeline. Most kinases of S. haematobium are very similar to those of its congener, S. mansoni, offering the prospect of designing chemicals that kill both species. Overall, this study provides a global insight into the kinome of S. haematobium and should assist the repurposing or discovery of drugs against schistosomiasis.

Usp16 regulates kinetochore localization of Plk1 to promote proper chromosome alignment in mitosis

During the G2 to M phase transition, a portion of mitotic regulator Plk1 localizes to the kinetochores and regulates the initiation of kinetochore-microtubule attachments for proper chromosome alignment. Once kinetochore-microtubule attachment is achieved, this portion of Plk1 is removed from the kinetochores as a result of ubiquitination. However, the crucial molecular mechanism that promotes the localization and the maintenance of Plk1 on the kinetochores until metaphase is still unclear. We report that ubiquitin-specific peptidase 16 (Usp16) plays a key role during this process. Usp16 deubiquitinates Plk1, resulting in an enhanced interaction with kinetochore-localized proteins such as BubR1, and thereby retains Plk1 on the kinetochores to promote proper chromosome alignment in early mitosis. Down-regulation of Usp16 causes increased ubiquitination and decreased kinetochore localization of Plk1. Thus, our data unveil a unique mechanism by which Usp16 promotes the localization and maintenance of Plk1 on the kinetochores for proper chromosome alignment.

Whole-exome sequencing reveals the mutational spectrum of testicular germ cell tumours

Testicular germ cell tumours (TGCTs) are the most common cancer in young men. Here we perform whole-exome sequencing (WES) of 42 TGCTs to comprehensively study the cancer's mutational profile. The mutation rate is uniformly low in all of the tumours (mean 0.5 mutations per Mb) as compared with common cancers, consistent with the embryological origin of TGCT. In addition to expected copy number gain of chromosome 12p and mutation of KIT, we identify recurrent mutations in the tumour suppressor gene CDC27 (11.9%). Copy number analysis reveals recurring amplification of the spermatocyte development gene FSIP2 (15.3%) and a 0.4 Mb region at Xq28 (15.3%). Two treatment-refractory patients are shown to harbour XRCC2 mutations, a gene strongly implicated in defining cisplatin resistance. Our findings provide further insights into genes involved in the development and progression of TGCT.

The oncogenic STP axis promotes triple-negative breast cancer via degradation of the REST tumor suppressor

Defining the molecular networks that drive breast cancer has led to therapeutic interventions and improved patient survival. However, the aggressive triple-negative breast cancer subtype (TNBC) remains recalcitrant to targeted therapies because its molecular etiology is poorly defined. In this study, we used a forward genetic screen to discover an oncogenic network driving human TNBC. SCYL1, TEX14, and PLK1 ("STP axis") cooperatively trigger degradation of the REST tumor suppressor protein, a frequent event in human TNBC. The STP axis induces REST degradation by phosphorylating a conserved REST phospho-degron and bridging REST interaction with the ubiquitin-ligase βTRCP. Inhibition of the STP axis leads to increased REST protein levels and impairs TNBC transformation, tumor progression, and metastasis. Expression of the STP axis correlates with low REST protein levels in human TNBCs and poor clinical outcome for TNBC patients. Our findings demonstrate that the STP-REST axis is a molecular driver of human TNBC.

An oncofetal and developmental perspective on testicular germ cell cancer

Germ cell tumors (GCTs) represent a diverse group of tumors presumably originating from (early fetal) developing germ cells. Most frequent are the testicular germ cell cancers (TGCC). Overall, TGCC is the most frequent malignancy in Caucasian males (20-40 years) and remains an important cause of (treatment related) mortality in these young men. The strong association between the phenotype of TGCC stem cell components and their totipotent ancestor (fetal primordial germ cell or gonocyte) makes these tumors highly relevant from an onco-fetal point of view. This review subsequently discusses the evidence for the early embryonic origin of TGCCs, followed by an overview of the crucial association between TGCC pathogenesis, genetics, environmental exposure and the (fetal) testicular micro-environment (genvironment). This culminates in an evaluation of three genvironmentally modulated hallmarks of TGCC directly related to the oncofetal pathogenesis of TGCC: (1) maintenance of pluripotency, (2) cell cycle control/cisplatin sensitivity and (3) regulation of proliferation/migration/apoptosis by KIT-KITL mediated receptor tyrosine kinase signaling. Briefly, TGCC exhibit identifiable stem cell components (seminoma and embryonal carcinoma) and progenitors that show large and consistent similarities to primordial/embryonic germ cells, their presumed totipotent cells of origin. TGCC pathogenesis depends crucially on a complex interaction of genetic and (micro-)environmental, i.e. genvironmental risk factors that have only been partly elucidated despite significant effort. TGCC stem cell components also show a high degree of similarity with embryonic stem/germ cells (ES) in the regulation of pluripotency and cell cycle control, directly related to their exquisite sensitivity to DNA damaging agents (e.g. cisplatin). Of note, (ES specific) micro-RNAs play a pivotal role in the crossover between cell cycle control, pluripotency and chemosensitivity. Moreover, multiple consistent observations reported TGCC to be associated with KIT-KITL mediated receptor tyrosine kinase signaling, a pathway crucially implicated in proliferation, migration and survival during embryogenesis including germ cell development. In conclusion, TGCCs are a fascinating model for onco-fetal developmental processes especially with regard to studying cell cycle control, pluripotency maintenance and KIT-KITL signaling. The knowledge presented here contributes to better understanding of the molecular characteristics of TGCC pathogenesis, translating to identification of at risk individuals and enhanced quality of care for TGCC patients (diagnosis, treatment and follow-up).

The mitosis-regulating and protein-protein interaction activities of astrin are controlled by aurora-A-induced phosphorylation

Cells display dramatic morphological changes in mitosis, where numerous factors form regulatory networks to orchestrate the complicated process, resulting in extreme fidelity of the segregation of duplicated chromosomes into two daughter cells. Astrin regulates several aspects of mitosis, such as maintaining the cohesion of sister chromatids by inactivating Separase and stabilizing spindle, aligning and segregating chromosomes, and silencing spindle assembly checkpoint by interacting with Src kinase-associated phosphoprotein (SKAP) and cytoplasmic linker-associated protein-1α (CLASP-1α). To understand how Astrin is regulated in mitosis, we report here that Astrin acts as a mitotic phosphoprotein, and Aurora-A phosphorylates Astrin at Ser(115). The phosphorylation-deficient mutant Astrin S115A abnormally activates spindle assembly checkpoint and delays mitosis progression, decreases spindle stability, and induces chromosome misalignment. Mechanistic analyses reveal that Astrin phosphorylation mimicking mutant S115D, instead of S115A, binds and induces ubiquitination and degradation of securin, which sequentially activates Separase, an enzyme required for the separation of sister chromatids. Moreover, S115A fails to bind mitosis regulators, including SKAP and CLASP-1α, which results in the mitotic defects observed in Astrin S115A-transfected cells. In conclusion, Aurora-A phosphorylates Astrin and guides the binding of Astrin to its cellular partners, which ensures proper progression of mitosis.

COX-2 inhibitors arrest prostate cancer cell cycle progression by down-regulation of kinetochore/centromere proteins

BACKGROUND

Previous studies have shown that COX-2 inhibitors inhibit cancer cell proliferation. However, the molecular mechanism remains elusive.

METHODS

Prostate cancer LNCaP, 22Rv1, and PC3 cells were cultured and treated with the COX-2 inhibitors celecoxib and CAY10404. Knockdown of COX-2 in LNCaP cells was carried out using lentiviral vector-loaded COX-2 shRNA. Cell cycle progression and cell proliferation were analyzed by flow cytometry, microscopy, cell counting, and the MTT assay. The antagonists of EP1, EP2, EP3, and EP4 were used to examine the effects of the PGE2 signaling. The effect of COX-2 inhibitors and COX-2 knockdown on expression of the kinetochore/centromere genes and proteins was determined by RT-PCR and immunoblotting.

RESULTS

Treatment with the COX-2 inhibitors celecoxib and CAY10404 or knockdown of COX-2 significantly inhibited prostate cancer cell proliferation. Flow-cytometric analysis and immunofluorescent staining confirmed the cell cycle arrested at the G2/M phase. Biochemical analysis showed that inhibition of COX-2 or suppression of COX-2 expression induced a dramatic down-regulation of key proteins in the kinetochore/centromere assembly, such as ZWINT, Cdc20, Ndc80, CENP-A, Bub1, and Plk1. Furthermore, the EP1 receptor antagonist SC51322, but not the EP2, EP3, and EP4 receptor antagonists, produced similar effects to the COX-2 inhibitors on cell proliferation and down-regulation of kinetochore/centromere proteins, suggesting that the effect of the COX-2 inhibition is through inactivation of the EP1 receptor signaling.

CONCLUSIONS

Our studies indicate that inhibition of COX-2 can arrest prostate cancer cell cycle progression through inactivation of the EP1 receptor signaling and down-regulation of kinetochore/centromere proteins.

Cause and consequence of cancer/testis antigen activation in cancer

Tumor cells frequently exhibit widespread epigenetic aberrations that significantly alter the repertoire of expressed proteins. In particular, it has been known for nearly 25 years that tumors frequently reactivate genes whose expression is typically restricted to germ cells. These gene products are classified as cancer/testis antigens (CTAs) owing to their biased expression pattern and their immunogenicity in cancer patients. While these genes have been pursued as targets for anticancer vaccines, whether these reactivated testis proteins have roles in supporting tumorigenic features is less studied. Recent evidence now indicates that these proteins can be directly employed by the tumor cell regulatory environment to support cell-autonomous behaviors. Here, we review the history of the CTA field and present recent findings indicating that CTAs can play functional roles in supporting tumorigenesis.

Comparative transcriptome analysis of obligately asexual and cyclically sexual rotifers reveals genes with putative functions in sexual reproduction, dormancy, and asexual egg production

BACKGROUND

Sexual reproduction is a widely studied biological process because it is critically important to the genetics, evolution, and ecology of eukaryotes. Despite decades of study on this topic, no comprehensive explanation has been accepted that explains the evolutionary forces underlying its prevalence and persistence in nature. Monogonont rotifers offer a useful system for experimental studies relating to the evolution of sexual reproduction due to their rapid reproductive rate and close relationship to the putatively ancient asexual bdelloid rotifers. However, little is known about the molecular underpinnings of sex in any rotifer species.

RESULTS

We generated mRNA-seq libraries for obligate parthenogenetic (OP) and cyclical parthenogenetic (CP) strains of the monogonont rotifer, Brachionus calyciflorus, to identify genes specific to both modes of reproduction. Our differential expression analysis identified receptors with putative roles in signaling pathways responsible for the transition from asexual to sexual reproduction. Differential expression of a specific copy of the duplicated cell cycle regulatory gene CDC20 and specific copies of histone H2A suggest that such duplications may underlie the phenotypic plasticity required for reproductive mode switch in monogononts. We further identified differential expression of genes involved in the formation of resting eggs, a process linked exclusively to sex in this species. Finally, we identified transcripts from the bdelloid rotifer Adineta ricciae that have significant sequence similarity to genes with higher expression in CP strains of B. calyciflorus.

CONCLUSIONS

Our analysis of global gene expression differences between facultatively sexual and exclusively asexual populations of B. calyciflorus provides insights into the molecular nature of sexual reproduction in rotifers. Furthermore, our results offer insight into the evolution of obligate asexuality in bdelloid rotifers and provide indicators important for the use of monogononts as a model system for investigating the evolution of sexual reproduction.

Identification of nine new susceptibility loci for testicular cancer, including variants near DAZL and PRDM14

Testicular germ cell tumor (TGCT) is the most common cancer in young men and is notable for its high familial risks. So far, six loci associated with TGCT have been reported. From genome-wide association study (GWAS) analysis of 307,291 SNPs in 986 TGCT cases and 4,946 controls, we selected for follow-up 694 SNPs, which we genotyped in a further 1,064 TGCT cases and 10,082 controls from the UK. We identified SNPs at nine new loci (1q22, 1q24.1, 3p24.3, 4q24, 5q31.1, 8q13.3, 16q12.1, 17q22 and 21q22.3) showing association with TGCT (P < 5 × 10(-8)), which together account for an additional 4-6% of the familial risk of TGCT. The loci include genes plausibly related to TGCT development. PRDM14, at 8q13.3, is essential for early germ cell specification, and DAZL, at 3p24.3, is required for the regulation of germ cell development. Furthermore, PITX1, at 5q31.1, regulates TERT expression and is the third TGCT-associated locus implicated in telomerase regulation.

Meta-analysis identifies four new loci associated with testicular germ cell tumor

We conducted a meta-analysis to identify new susceptibility loci for testicular germ cell tumor (TGCT). In the discovery phase, we analyzed 931 affected individuals and 1,975 controls from 3 genome-wide association studies (GWAS). We conducted replication in 6 independent sample sets comprising 3,211 affected individuals and 7,591 controls. In the combined analysis, risk of TGCT was significantly associated with markers at four previously unreported loci: 4q22.2 in HPGDS (per-allele odds ratio (OR) = 1.19, 95% confidence interval (CI) = 1.12-1.26; P = 1.11 × 10(-8)), 7p22.3 in MAD1L1 (OR = 1.21, 95% CI = 1.14-1.29; P = 5.59 × 10(-9)), 16q22.3 in RFWD3 (OR = 1.26, 95% CI = 1.18-1.34; P = 5.15 × 10(-12)) and 17q22 (rs9905704: OR = 1.27, 95% CI = 1.18-1.33; P = 4.32 × 10(-13) and rs7221274: OR = 1.20, 95% CI = 1.12-1.28; P = 4.04 × 10(-9)), a locus that includes TEX14, RAD51C and PPM1E. These new TGCT susceptibility loci contain biologically plausible genes encoding proteins important for male germ cell development, chromosomal segregation and the DNA damage response.

Regulatory mechanisms of kinetochore-microtubule interaction in mitosis

Interaction of microtubules with kinetochores is fundamental to chromosome segregation. Kinetochores initially associate with lateral surfaces of microtubules and subsequently become attached to microtubule ends. During these interactions, kinetochores can move by sliding along microtubules or by moving together with depolymerizing microtubule ends. The interplay between kinetochores and microtubules leads to the establishment of bi-orientation, which is the attachment of sister kinetochores to microtubules from opposite spindle poles, and subsequent chromosome segregation. Molecular mechanisms underlying these processes have been intensively studied over the past 10 years. Emerging evidence suggests that the KNL1-Mis12-Ndc80 (KMN) network plays a central role in connecting kinetochores to microtubules, which is under fine regulation by a mitotic kinase, Aurora B. However, a growing number of additional molecules are being shown to be involved in the kinetochore-microtubule interaction. Here I overview the current range of regulatory mechanisms of the kinetochore-microtubule interaction, and discuss how these multiple molecules contribute cooperatively to allow faithful chromosome segregation.

Switching Polo-like kinase-1 on and off in time and space

Polo-like kinase (Plk)1 executes several essential functions to promote cell division. These functions range from centrosome maturation in late G2 phase to the regulation of cytokinesis, which necessitates precise separation of Plk1-dependent substrate phosphorylation over time. Multiple levels of control are in place to ensure that Plk1-dependent phosphorylation of its various substrates is properly coordinated in time and space. Here, we review the current knowledge on the mechanisms that enforce the temporal and spatial control of Plk1 activity, and how this results in coordinated phosphorylation of its many different substrates. We also review a number of newly discovered functions of Plk1 that provide more insights into the spatiotemporal control of Plk1-dependent substrate phosphorylation.