Structural specializations of the sperm tail

Sperm motility is crucial to reproductive success in sexually reproducing organisms. Impaired sperm movement causes male infertility, which is increasing globally. Sperm are powered by a microtubule-based molecular machine-the axoneme-but it is unclear how axonemal microtubules are ornamented to support motility in diverse fertilization environments. Here, we present high-resolution structures of native axonemal doublet microtubules (DMTs) from sea urchin and bovine sperm, representing external and internal fertilizers. We identify \u3e60 proteins decorating sperm DMTs; at least 15 are sperm associated and 16 are linked to infertility. By comparing DMTs across species and cell types, we define core microtubule inner proteins (MIPs) and analyze evolution of the tektin bundle. We identify conserved axonemal microtubule-associated proteins (MAPs) with unique tubulin-binding modes. Additionally, we identify a testis-specific serine/threonine kinase that links DMTs to outer dense fibers in mammalian sperm. Our study provides structural foundations for understanding sperm evolution, motility, and dysfunction at a molecular level

Co-Deletion of Chromosome 1p/19q and IDH1/2 Mutation in Glioma Subsets of Brain Tumors in Chinese Patients

OBJECTIVE: To characterize co-deletion of chromosome 1p/19q and IDH1/2 mutation in Chinese brain tumor patients and to assess their associations with clinical features. METHODS: In a series of 528 patients with gliomas, pathological and radiological materials were reviewed. Pathological constituents of tumor subsets, incidences of 1p/19q co-deletion and IDH1/2 mutation in gliomas by regions and sides in the brain were analyzed. RESULTS: Overall, 1p and 19q was detected in 339 patients by FISH method while the sequence of IDH1/2 was determined in 280 patients. Gliomas of frontal, temporal and insular origin had significantly different pathological constituents of tumor subsets (P<0.001). Gliomas of frontal origin had significantly higher incidence of 1p/19q co-deletion (50.4%) and IDH1/2 mutation (73.5%) than those of non-frontal origin (27.0% and 48.5%, respectively) (P<0.001), while gliomas of temporal origin had significantly lower incidence of 1p/19q co-deletion (23.9%) and IDH1/2 mutation (41.7%) than those of non-temporal origin (39.9% and 63.2%, respectively) (P = 0.013 and P = 0.003, respectively). Subgroup analysis confirmed these findings in oligoastrocytic and oligodendroglial tumors, respectively. Although the difference of 1p/19q co-deletion was not statistically significant in temporal oligodendroglial tumors, the trend was marginally significant (P = 0.082). However, gliomas from different sides of the brain did not show significant different pathological constituents, incidences of 1p/19q co-deletion or IDH1/2 mutation. CONCLUSION: Preferential distribution of pathological subsets, 1p/19q co-deletion and IDH1/2 mutation were confirmed in some brain regions in Chinese glioma patients, implying their distinctive tumor genesis and predictive value for prognosis

Structural specializations of the sperm tail

Sperm motility is crucial to reproductive success in sexually reproducing organisms. Impaired sperm movement causes male infertility, which is increasing globally. Sperm are powered by a microtubule-based molecular machine-the axoneme-but it is unclear how axonemal microtubules are ornamented to support motility in diverse fertilization environments. Here, we present high-resolution structures of native axonemal doublet microtubules (DMTs) from sea urchin and bovine sperm, representing external and internal fertilizers. We identify >60 proteins decorating sperm DMTs; at least 15 are sperm associated and 16 are linked to infertility. By comparing DMTs across species and cell types, we define core microtubule inner proteins (MIPs) and analyze evolution of the tektin bundle. We identify conserved axonemal microtubule-associated proteins (MAPs) with unique tubulin-binding modes. Additionally, we identify a testis-specific serine/threonine kinase that links DMTs to outer dense fibers in mammalian sperm. Our study provides structural foundations for understanding sperm evolution, motility, and dysfunction at a molecular level

A Toxin-Antitoxin Module in Bacillus subtilis Can Both Mitigate and Amplify Effects of Lethal Stress

Bacterial type-2 (protein-protein) toxin-antitoxin (TA) modules are two-gene operons that are thought to participate in the response to stress. Previous work with Escherichia coli has led to a debate in which some investigators conclude that the modules protect from stress, while others argue that they amplify lethal stress and lead to programmed cell death. To avoid ambiguity arising from the presence of multiple TA modules in E. coli, the effect of the sole type-2 toxin-antitoxin module of Bacillus subtilis was examined for several types of lethal stress.Genetic knockout of the toxin gene, ndoA (ydcE), conferred protection to lethal stressors that included kanamycin, moxifloxacin, hydrogen peroxide, and UV irradiation. However, at low doses of UV irradiation the ndoA deficiency increased lethality. Indeed, gradually increasing UV dose with the ndoA mutant revealed a crossover response--from the mutant being more sensitive than wild-type cells to being less sensitive. For high temperature and nutrient starvation, the toxin deficiency rendered cells hypersensitive. The ndoA deficiency also reduced sporulation frequency, indicating a role for toxin-antitoxin modules in this developmental process. In the case of lethal antimicrobial treatment, deletion of the toxin eliminated a surge in hydrogen peroxide accumulation observed in wild-type cells.A single toxin-antitoxin module can mediate two opposing effects of stress, one that lowers lethality and another that raises it. Protective effects are thought to arise from toxin-mediated inhibition of translation based on published work. The enhanced, stress-mediated killing probably involves toxin-dependent accumulation of reactive oxygen species, since a deficiency in the NdoA toxin suppressed peroxide accumulation following antimicrobial treatment. The type and perhaps the level of stress appear to be important for determining whether this toxin will have a protective or detrimental effect

Gastrointestinal Hyperplasia with Altered Expression of DNA Polymerase β

Background: Altered expression of DNA polymerase β (Pol β) has been documented in a large percentage of human tumors. However, tumor prevalence or predisposition resulting from Pol β over-expression has not yet been evaluated in a mouse model. Methodology/Principal Findings: We have recently developed a novel transgenic mouse model that over-expresses Pol β. These mice present with an elevated incidence of spontaneous histologic lesions, including cataracts, hyperplasia of Brunner's gland and mucosal hyperplasia in the duodenum. In addition, osteogenic tumors in mice tails, such as osteoma and osteosarcoma were detected. This is the first report of elevated tumor incidence in a mouse model of Pol β over-expression. These findings prompted an evaluation of human gastrointestinal tumors with regard to Pol β expression. We observed elevated expression of Pol β in stomach adenomas and thyroid follicular carcinomas, but reduced Pol β expression in esophageal adenocarcinomas and squamous carcinomas. Conclusions/Significance: These data support the hypothesis that balanced and proficient base excision repair protein expression and base excision repair capacity is required for genome stability and protection from hyperplasia and tumor formation

Transcriptional Coactivation of Bone-Specific Transcription Factor Cbfa1 by TAZ

Core-binding factor 1 (Cbfa1; also called Runx2) is a transcription factor belonging to the Runt family of transcription factors that binds to an osteoblast-specific cis-acting element (OSE2) activating the expression of osteocalcin, an osteoblast-specific gene. Using the yeast two-hybrid system, we identified a transcriptional coactivator, TAZ (transcriptional coactivator with PDZ-binding motif), that binds to Cbfa1. A functional relationship between Cbfa1 and TAZ is demonstrated by the coimmunoprecipitation of TAZ by Cbfa1 and by the fact that TAZ induces a dose-dependent increase in the activity of osteocalcin promoter-luciferase constructs by Cbfa1. A dominant-negative construct of TAZ in which the coactivation domains have been deleted reduces osteocalcin gene expression down to basal levels. NIH 3T3, MC 3T3, and ROS 17/2.8 cells showed the expected nuclear localization of Cbfa1, whereas TAZ was distributed throughout the cytoplasm with some nuclear localization when transfected with either Cbfa1 or TAZ. Upon cotransfection by both Cbfa1 and TAZ, the transfected TAZ shows predominant nuclear localization. The dominant-negative construct of TAZ shows minimal nuclear localization upon cotransfection with Cbfa1. These data indicate that TAZ is a transcription coactivator for Cbfa1 and may be involved in the regulation of osteoblast differentiation