The Wilms Tumor Gene,Wt1, Is Critical for Mouse Spermatogenesis via Regulation of Sertoli Cell Polarity and Is Associated with Non-Obstructive Azoospermia in Humans

Azoospermia is one of the major reproductive disorders which cause male infertility in humans; however, the etiology of this disease is largely unknown. In the present study, six missense mutations of WT1 gene were detected in 529 human patients with non-obstructive azoospermia (NOA), indicating a strong association between WT1 mutation and NOA. The Wilms tumor gene, Wt1, is specifically expressed in Sertoli cells (SCs) which support spermatogenesis. To examine the functions of this gene in spermatogenesis, Wt1 was deleted in adult testis using Wt1^flox and Cre-ER^TM mice strains. We found that inactivation of Wt1 resulted in massive germ cell death and only SCs were present in most of the seminiferous tubules which was very similar to NOA in humans. In investigating the potential mechanism for this, histological studies revealed that the blood–testis barrier (BTB) was disrupted in Wt1 deficient testes. In vitro studies demonstrated that Wt1 was essential for cell polarity maintenance in SCs. Further studies found that the expression of cell polarity associated genes (Par6b and E-cadherin) and Wnt signaling genes (Wnt4, Wnt11) were downregulated in Wt1 deficient SCs, and that the expression of Par6b and E-cadherin was regulated by Wnt4. Our findings suggest that Wt1 is important in spermatogenesis by regulating the polarity of SCs via Wnt signaling pathway and that WT1 mutation is one of the genetic causes of NOA in humans.     

Molecular and Clinical Characteristics of Clonal Complex 59 Methicillin-Resistant Staphylococcus aureus Infections in Mainland China

Detailed molecular analyses of Clonal Complex 59 (CC59) methicillin-resistant Staphylococcus aureus (MRSA) isolates from children in seven major cities across Mainland China were examined. A total of 110 CC59 isolates from invasive and non-invasive diseases were analyzed by multilocus sequence typing (MLST), Staphylococcus cassette chromosome mec (SCCmec) typing, staphylococcal protein A (spa) typing and pulsed-field gel electrophoresis (PFGE). Antibiotics susceptibilities, carriage of plasmids and 42 virulence genes and the expression of virulence factors were examined. ST59 (101/110, 91.8%) was the predominant sequence type (ST), while single locus variants (SLVs) belonging to ST338 (8/110, 7.3%) and ST375 (1/110, 0.9%) were obtained. Three SCCmec types were found, namely type III (2.7%), type IV (74.5%) and type V (22.7%). Seven spa types including t437, which accounted for 87.3%, were determined. Thirteen PFGE types were obtained. PFGE types A and B were the major types totally accounting for 81.8%. The dominant clone was ST59-t437-IVa (65.5%), followed by ST59-t437-V (14.5%). The positive rate of luks-PV and lukF-PV PVL encoding (pvl) gene was 55.5%. Plasmids were detected in 83.6% (92/110) of the strains. The plasmid size ranging from 23.4 kb to 50 kb was most prevalent which accounted for 83.7% (77/92). A significantly lower expression of hla was found in ST59-t437-IVa compared with ST59-t437-V. Among the 110 cases, 61.8% of the patients were less than 1 year old. A total of 90 cases (81.8%) were community-associated (CA) infections whereas 20 cases (18.2%) were hospital-associated (HA) infections. Out of the 110 patients, 36.4% (40/110) were diagnosed with invasive infectious diseases in which ST59-t437-IVa accounted for 67.5% (27/40). In brief, ST59-t437-IVa was proved as the dominant clone in CC59 MRSA strains. The carriage rate of pvl gene was high. CC59 MRSA could result in CA and HA infections. The majortiy of MRSA infection children were in young age.     

Ubiquitin ligase A20 regulates p53 protein in human colon epithelial cells

Background

Intestinal polyps may further develop into colon cancer; the pathogenesis is not clear. The p53 gene is an important anti-cancer gene in the body, which is suppressed in cancer. The ubiquitin E3 ligase A20 (A20) plays a role in regulating the activities of epithelial cells. This study was designed to investigate the role of the colon polyp epithelium-derived A20 in the pathogenesis of colon cancer.

Results

Eighty-eight colon cancer patients and 136 colon polyp patients were recruited into this study. Human colon cancer tissue, the epithelium of adenomas polyp and hyperplastic polyp showed high levels of A20, which had a positive correlation with the cancerous tendency of colon polyps. The levels of A20 were much higher in the adenomas and hyperplastic polyps than that in the inflammatory polyps; the latter showed less cancerous tendency. A20 bound p53 to form complexes in colon cancer tissue and colon polyps. Over expression of A20 suppresses P53 protein levels in the HEK293 cells.

Conclusions

A20 may play an important role in the cancerous tendency of colon polyposis.     

A Hypomorphic Lsd1 Allele Results in Heart Development Defects in Mice

Lysine-specific demethylase 1 (Lsd1/Aof2/Kdm1a), the first enzyme with specific lysine demethylase activity to be described, demethylates histone and non-histone proteins and is essential for mouse embryogenesis. Lsd1 interacts with numerous proteins through several different domains, most notably the tower domain, an extended helical structure that protrudes from the core of the protein. While there is evidence that Lsd1-interacting proteins regulate the activity and specificity of Lsd1, the significance and roles of such interactions in developmental processes remain largely unknown. Here we describe a hypomorphic Lsd1 allele that contains two point mutations in the tower domain, resulting in a protein with reduced interaction with known binding partners and decreased enzymatic activity. Mice homozygous for this allele die perinatally due to heart defects, with the majority of animals suffering from ventricular septal defects. Molecular analyses revealed hyperphosphorylation of E-cadherin in the hearts of mutant animals. These results identify a previously unknown role for Lsd1 in heart development, perhaps partly through the control of E-cadherin phosphorylation.     

质膜H~＋－ATP酶在玉米叶片渗透调节中的作用

干早胁迫下,玉米幼叶生长部位质膜Ｈ＋－ＡＴＰ酶活性显著上升,游离脯氨酸、可溶性糖和无机离子亦同时在玉米叶片生长部位大量积累,二者之间呈明显的正相关．质膜Ｈ＋－ＡＴＰ酶的专一性抑制剂Ｎａ３ＶＯ４在干旱胁迫下强烈抑制游离脯氨酸的积累,说明ＰＭＨ＋－ＡＴＰａｓｅ参与了玉米叶片的渗透调节过程．     

Perspectives on the origin of microfilaments,microtubules, the relevant chaperonin system and cytoskeletal motors--a commentary on the spirochaete origin of flagella

The origin of cytoskeleton and the origin of relevant intracelluar transportation system are big problemsfor understanding the emergence of eukaryotic cells. The present article snmmarized relevant information of evidences and molecular traces on the origin of actin, tubulin, the chaperonin system for folding them,myosins, kinesins, axonemal dyneins and cytoplasmic dyneins. On this basis the authors proposed a seriesof works, which should be done in the future, and indicated the ways for reaching the targets.These targets are mainly: 1) the reconstruction of evolutionary path from MreB protein of archaeal ancestor ofeukaryotic cells to typical actin; 2) the finding of the MreB or MreB-related proteins in crenarchaea andusing them to examine J. A. Lake‘‘s hypothesis on the origin of eukaryote from “eocytes“ (crenarchaea);3) the examinations of the existence and distribution of cytoskeleton made of MreB-related protein withincoccoid archaea, especially in amoeboid archaeon Thermoplasm acidophilnm; 4) using Thermoplasma asa model of archaeal ancestor of eukaryotic cells; 5) the searching for the homolog of ancestral dynein inpresent-day living archaea. During the writing of this article, Margulis‘‘ famous spirochaete hypothesis onthe origin of flagella and cilia was unexpectedly involved and analyzed from aspects of tubulin.% dyneinsand spirochaetes. Actually, spirochaete cannot be reasonably ass,med as the ectosymbiotic ancestor of eukaryotic flagella and cilia, since their swing depends upon large amount of bacterial flagella beneath theflexible outer wall, but not depends upon their intracelluar tubules and the assumed dyneins. In this case,if they had “evolved“ into cilia and lost their bacterial fiagella, they would immediately become immobile!In fact, tubulin and dynein-like proteins have not been found in any spirochaete.     

塞内卡病毒A结构蛋白VP2诱导PK-15细胞自噬的研究

本研究在塞内卡病毒A(Senecavirus A,SVA)诱导自噬的基础上,着重探究VP2蛋白在细胞自噬过程中的作用。构建VP2基因真核表达载体pcDNA3.1-VP2,将其转染至PK-15细胞,通过检测自噬蛋白和相关基因的表达情况,明确VP2蛋白对细胞自噬的影响。结果显示,本研究成功构建了pcDNA3.1-VP2真核表达载体,且SVA VP2基因在PK-15细胞中正常表达;与对照组相比,VP2蛋白显著上调LC3蛋白的表达水平（P<0.01）;同时,自噬基因LC3、Beclin-1和ATG5转录水平均显著提高（P<0.01）。综上所述,本研究证实SVA VP2蛋白可诱导PK-15细胞自噬,且VP2蛋白与自噬蛋白和基因表达水平呈正相关,为进一步研究病毒感染与致病机制打下基础。     

Comparative genomics analyses of alpha-keratins reveal insights into evolutionary adaptation of marine mammals

Background

Diversity of hair in marine mammals was suggested as an evolutionary innovation to adapt aquatic environment, yet its genetic basis remained poorly explored. We scanned α-keratin genes, one major structural components of hair, in 16 genomes of mammalian species, including seven cetaceans, two pinnipeds, polar bear, manatee and five terrestrial species.

Results

Extensive gene loss and high pseudogenization rate of α-keratin genes were identified in cetaceans when compared to terrestrial artiodactylans (average number of α-keratins 37.29 vs. 58.33; pseudogenization rate 29.89% vs. 8.00%), especially of hair follicle-specific keratin genes (average pseudogenization rate in cetaceans of 43.88% relative to 3.80% artiodactylian average). Compared to toothed whale, the much more number of intact functional α-keratin genes was examined in the baleen whale that had specific keratinized baleen. In contrast, the number of keratin genes in pinnipeds, polar bear and manatee were comparable to those of their respective terrestrial relatives. Additionally, four keratin genes (K39, K9, K42, and K74) were found to be pseudogenes or lost uniquely in cetaceans and manatees.

Conclusions

Species-specific evolution of α-keratin gene family identified in the marine mammals might be responsible for their different hair characteristics. Increased gene loss and pseudogenization rate identified in cetacean lineages was likely to contribute to hair-less phenotype to adaptation for complete aquatic environment. However, the fully aquatic manatee still remained the comparable number of intact genes to its terrestrial relative, probably due to its perioral bristles and bristle-like hairs on the oral disk. By contrast, similar evolution pattern of α-keratin gene repertoire in the pinnipeds, polar bear and their terrestrial relatives was likely due to abundant hair to keep warm when they went ashore. Interestingly, some keratin genes were exclusively lost in cetaceans and manatees, likely as a result of convergent hair-loss phenotype to inhabit completely aquatic environment in both groups.

     

N-acetylglucosaminyltransferase V mediates cell migration and invasion of mouse mammary tumor cells 4TO7 via RhoA and Rac1 signaling pathway

In tumor cells, alterations in cellular glycosylation may play a key role in their metastatic behavior. Using small interfering RNA against GnT-V, we found that the expression of GnT-V and β1,6GlcNAc branching were significantly reduced which was particularly accompanied by the arrest in both cell migration and invasion as compared to the negative control. Moreover, the suppressed GnT-V expression by siRNA technique inactivated the signaling molecules including Rac1, cofilin, Erk and Akt, and activated RhoA levels in cells lacking GnT-V, but revealed no impact on Cdc42 activity. All these notions disclose for the first time that GnT-V and β1, 6GlcNAc branching mediate the cell migration and invasion in Rac1-positive and RhoA-negative regulatory manners. Yunxue Zhao and Jing Li contributed equally to this work.     

Mapping quantitative trait loci associated with arsenic accumulation in rice (Oryza sativa)

The quantitative trait loci (QTLs) associated with arsenic (As) accumulation in rice were mapped using a doubled haploid population established by anther culture of F1 plants from a cross between a Japonica cultivar CJ06 and an Indica cultivar TN1 (Oryza sativa). Four QTLs for arsenic (As) concentrations were detected in the map. At the seedling stage, one QTL was mapped on chromosome 2 for As concentrations in shoots with 24.4% phenotypic variance and one QTL for As concentrations in roots was detected on chromosome 3. At maturity, two QTLs for As concentrations in grains were found on chromosomes 6 and 8, with 26.3 and 35.2% phenotypic variance, respectively. No common loci were detected among these three traits. Interestingly, the QTL on chromosome 8 was found to be colocated for As concentrations in grain at maturity and shoot phosphorus (P) concentrations at seedling stage. These results provide an insight into the genetic basis of As uptake and accumulation in rice, and will be useful in identifying genes associated with As accumulation.