Somatic Mutational Landscape of Splicing Factor Genes and Their Functional Consequences across 33 Cancer Types

Hotspot mutations in splicing factor genes have been recently reported at high frequency in hematological malignancies, suggesting the importance of RNA splicing in cancer. We analyzed whole-exome sequencing data across 33 tumor types in The Cancer Genome Atlas (TCGA), and we identified 119 splicing factor genes with significant non-silent mutation patterns, including mutation over-representation, recurrent loss of function (tumor suppressor-like), or hotspot mutation profile (oncogene-like). Furthermore, RNA sequencing analysis revealed altered splicing events associated with selected splicing factor mutations. In addition, we were able to identify common gene pathway profiles associated with the presence of these mutations. Our analysis suggests that somatic alteration of genes involved in the RNA-splicing process is common in cancer and may represent an underappreciated hallmark of tumorigenesis

The cytoskeleton in spermatogenesis

As germ cells progress through spermatogenesis, they undergo a dramatic transformation, wherein a single, diploid spermatogonial stem cell ultimately produces thousands of highly specialised, haploid spermatozoa. The cytoskeleton is an integral aspect of all eukaryotic cells. It concomitantly provides both structural support and functional pliability, performing key roles in many fundamental processes including, motility, intracellular trafficking, differentiation and cell division. Accordingly, cytoskeletal dynamics underlie many key spermatogenic processes. This review summarises the organisational and functional aspects of the four major cytoskeletal components (actin, microtubules, intermediate filaments and septins) during the various spermatogenic phases in mammals. We focus on the cytoskeletal machinery of both germ cells and Sertoli cells, and thus, highlight the critical importance of a dynamic and precisely regulated cytoskeleton for male fertility.Jessica E M Dunleavy, Moira K O’Bryan, Peter G Stanton and Liza O’Donnel

Pituitary and testicular endocrine responses to exogenous gonadotrophin-releasing hormone (GnRH) and luteinising hormone in male dogs treated with GnRH agonist implants

The present study tested whether exogenous gonadotrophin-releasing hormone (GnRH) and luteinising hormone (LH) can stimulate LH and testosterone secretion in dogs chronically treated with a GnRH superagonist. Twenty male adult dogs were assigned to a completely randomised design comprising five groups of four animals. Each dog in the control group received a blank implant (placebo) and each dog in the other four groups received a 6-mg implant containing a slow-release formulation of deslorelin (d-Trp6-Pro 9-des-Gly10?LH-releasing hormone ethylamide). The same four control dogs were used for all hormonal challenges, whereas a different deslorelin-implanted group was used for each challenge. Native GnRH (5 μg kg-1 bodyweight, i.v.) was injected on Days 15, 25, 40 and 100 after implantation, whereas bovine LH (0.5 μg kg-1 bodyweight, i.v.) was injected on Days 16, 26, 41 and 101. On all occasions after Day 25-26 postimplantation, exogenous GnRH and LH elicited higher plasma concentrations of LH and testosterone in control than deslorelin-treated animals (P < 0.05). It was concluded that, in male dogs, implantation of a GnRH superagonist desensitised the pituitary gonadotrophs to GnRH and also led to a desensitisation of the Leydig cells to LH. This explains, at least in part, the profound reduction in the production of androgen and spermatozoa in deslorelin-treated male dogs

Gonadotropin suppression in men leads to a reduction in claudin-11 at the Sertoli cell tight junction

STUDY QUESTION Are Sertoli cell tight junctions (TJs) disrupted in men undergoing hormonal contraception? SUMMARY ANSWER Localization of the key Sertoli cell TJ protein, claudin-11, was markedly disrupted by 8 weeks of gonadotropin suppression, the degree of which was related to the extent of adluminal germ cell suppression. WHAT IS KNOWN ALREADY Sertoli cell TJs are vital components of the blood–testis barrier (BTB) that sequester developing adluminal meiotic germ cells and spermatids from the vascular compartment. Claudin-11 knockout mice are infertile; additionally claudin-11 is spatially disrupted in chronically gonadotropin-suppressed rats coincident with a loss of BTB function, and claudin-11 is disorganized in various human testicular disorders. These data support the Sertoli cell TJ as a potential site of hormonal contraceptive action. STUDY DESIGN, SIZE, DURATION BTB proteins were assessed by immunohistochemistry (n = 16 samples) and mRNA (n = 18 samples) expression levels in available archived testis tissue from a previous study of 22 men who had undergone 8 weeks of gonadotropin suppression and for whom meiotic and post-meiotic germ cell numbers were available. The gonadotropin suppression regimens were (i) testosterone enanthate (TE) plus the GnRH antagonist, acyline (A); (ii) TE + the progestin, levonorgestrel, (LNG); (iii) TE + LNG + A or (iv) TE + LNG + the 5α-reductase inhibitor, dutasteride (D). A control group consisted of seven additional men, with three archived samples available for this study. PARTICIPANTS/MATERIALS, SETTINGS, METHODS Immunohistochemical localization of claudin-11 (TJ) and other junctional type markers [ZO-1 (cytoplasmic plaque), β-catenin (adherens junction), connexin-43 (gap junction), vinculin (ectoplasmic specialization) and β-actin (cytoskeleton)] and quantitative PCR was conducted using matched frozen testis tissue. MAIN RESULTS AND THE ROLE OF CHANCE Claudin-11 formed a continuous staining pattern at the BTB in control men. Regardless of gonadotropin suppression treatment, claudin-11 localization was markedly disrupted and was broadly associated with the extent of meiotic/post-meiotic germ cell suppression; claudin-11 staining was (i) punctate (i.e. ‘spotty’ appearance) at the basal aspect of tubules when the average numbers of adluminal germ cells were &lt;15% of control, (ii) presented as short fragments with cytoplasmic extensions when numbers were 15–25% of control or (iii) remained continuous when numbers were &gt;40% of control. Changes in localization of connexin-43 and vinculin were also observed (smaller effects than for claudin-11) but ZO-1, β-catenin and β-actin did not differ, compared with control. LIMITATIONS, REASONS FOR CAUTION Claudin-11 was the only Sertoli cell TJ protein investigated, but it is considered to be the most pivotal of constituent proteins given its known implication in infertility and BTB function. We were limited to testis samples which had been gonadotropin-suppressed for 8 weeks, shorter than the 74-day spermatogenic wave, which may account for the heterogeneity in claudin-11 and germ cell response observed among the men. Longer suppression (12–24 weeks) is known to suppress germ cells further and claudin-11 disruption may be more uniform, although we could not access such samples. WIDER IMPLICATIONS OF THE FINDINGS These findings are important for our understanding of the sites of action of male hormonal contraception, because they suggest that BTB function could be ablated following long-term hormone suppression treatment