Hsiao g Chan

Whole-genome and whole-exome sequencing of bladder cancer identifies frequent alterations in genes involved in sister chromatid cohesion and segregation

Bladder cancer is one of the most common cancers worldwide, with transitional cell carcinoma (TCC) being the predominant form. Here we report a genomic analysis of TCC by both whole-genome and whole-exome sequencing of 99 individuals with TCC. Beyond confirming recurrent mutations in genes previously identified as being mutated in TCC, we identified additional altered genes and pathways that were implicated in TCC. Notably, we discovered frequent alterations in STAG2 and ESPL1, two genes involved in the sister chromatid cohesion and segregation (SCCS) process. Furthermore, we also detected a recurrent fusion involving FGFR3 and TACC3, another component of SCCS, by transcriptome sequencing of 42 DNA-sequenced tumors. Overall, 32 of the 99 tumors (32%) harbored genetic alterations in the SCCS process. Our analysis provides evidence that genetic alterations affecting the SCCS process may be involved in bladder tumorigenesis and identifies a new therapeutic possibility for bladder cancer.

An epididymis-specific |[beta]|-defensin is important for the initiation of sperm maturation

Although the role of the epididymis, a male accessory sex organ, in sperm maturation has been established for nearly four decades, the maturation process itself has not been linked to a specific molecule of epididymal origin. Here we show that Bin1b, a rat epididymis-specific β-defensin with antimicrobial activity, can bind to the sperm head in different regions of the epididymis with varied binding patterns. In addition, Bin1b-expressing cells, either of epididymal origin or from a Bin1b-transfected cell line, can induce progressive sperm motility in immotile immature sperm. This induction of motility is mediated by the Bin1b-induced uptake of Ca2+, a mechanism that has a less prominent role in maintaining motility in mature sperm. In vivo antisense experiments show that suppressed expression of Bin1b results in reduced binding of Bin1b to caput sperm and in considerable attenuation of sperm motility and progressive movement. Thus, β-defensin is important for the acquisition of sperm motility and the initiation of sperm maturation.

Cystic fibrosis transmembrane conductance regulator is vital to sperm fertilizing capacity and male fertility

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel, mutations of which cause cystic fibrosis, a disease characterized by defective Cl− and HCO3− transport. Although >95% of all CF male patients are infertile because of congenital bilateral absence of the vas deferens (CBAVD), the question whether CFTR mutations are involved in other forms of male infertility is under intense debates. Here we report that CFTR is detected in both human and mouse sperm. CFTR inhibitor or antibody significantly reduces the sperm capacitation, and the associated HCO3−-dependent events, including increases in intracellular pH, cAMP production and membrane hyperpolarization. The fertilizing capacity of the sperm obtained from heterozygous CFTR mutant mice is also significantly lower compared with that of the wild-type. These results suggest that CFTR in sperm may be involved in the transport of HCO3− important for sperm capacitation and that CFTR mutations with impaired CFTR function may lead to reduced sperm fertilizing capacity and male infertility other than CBAVD.

Involvement of CFTR in uterine bicarbonate secretion and the fertilizing capacity of sperm

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-activated chloride channel expressed in a wide variety of epithelial cells, mutations of which are responsible for the hallmark defective chloride secretion observed in cystic fibrosis (CF). Although CFTR has been implicated in bicarbonate secretion, its ability to directly mediate bicarbonate secretion of any physiological significance has not been shown. We demonstrate here that endometrial epithelial cells possess a CFTR-mediated bicarbonate transport mechanism. Co-culture of sperm with endometrial cells treated with antisense oligonucleotide against CFTR, or with bicarbonate secretion-defective CF epithelial cells, resulted in lower sperm capacitation and egg-fertilizing ability. These results are consistent with a critical role of CFTR in controlling uterine bicarbonate secretion and the fertilizing capacity of sperm, providing a link between defective CFTR and lower female fertility in CF.

The cystic fibrosis transmembrane conductance regulator in reproductive health and disease

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel regulated by cAMP‐dependent phosphorylation, which is expressed in epithelial cells of a wide variety of tissues including the reproductive tracts. Mutations in the gene encoding CFTR cause cystic fibrosis, a common genetic disease in Caucasian populations with a multitude of clinical manifestations including infertility/subfertility in both sexes. However, the physiological role of CFTR in reproduction and its involvement in the pathogenesis of reproductive diseases remain largely unknown. This review discusses the role of CFTR in regulating fluid volume and bicarbonate secretion in the reproductive tracts and their importance in various reproductive events. We also discuss the contribution of CFTR dysfunction to a number of pathological conditions. The evidence presented is consistent with an important role of CFTR in reproductive health and disease, suggesting that CFTR might be a potential target for the diagnosis and treatment of reproductive diseases including infertility.

Implant-Derived Magnesium Induces Local Neuronal Production of CGRP to Improve Bone-Fracture Healing in Rats

Orthopedic implants containing biodegradable magnesium have been used for fracture repair with considerable efficacy; however, the underlying mechanisms by which these implants improve fracture healing remain elusive. Here we show the formation of abundant new bone at peripheral cortical sites after intramedullary implantation of a pin containing ultrapure magnesium into the intact distal femur in rats. This response was accompanied by substantial increases of neuronal calcitonin gene-related polypeptide-α (CGRP) in both the peripheral cortex of the femur and the ipsilateral dorsal root ganglia (DRG). Surgical removal of the periosteum, capsaicin denervation of sensory nerves or knockdown in vivo of the CGRP-receptor-encoding genes Calcrl or Ramp1 substantially reversed the magnesium-induced osteogenesis that we observed in this model. Overexpression of these genes, however, enhanced magnesium-induced osteogenesis. We further found that an elevation of extracellular magnesium induces magnesium transporter 1 (MAGT1)-dependent and transient receptor potential cation channel, subfamily M, member 7 (TRPM7)-dependent magnesium entry, as well as an increase in intracellular adenosine triphosphate (ATP) and the accumulation of terminal synaptic vesicles in isolated rat DRG neurons. In isolated rat periosteum-derived stem cells, CGRP induces CALCRL- and RAMP1-dependent activation of cAMP-responsive element binding protein 1 (CREB1) and SP7 (also known as osterix), and thus enhances osteogenic differentiation of these stem cells. Furthermore, we have developed an innovative, magnesium-containing intramedullary nail that facilitates femur fracture repair in rats with ovariectomy-induced osteoporosis. Taken together, these findings reveal a previously undefined role of magnesium in promoting CGRP-mediated osteogenic differentiation, which suggests the therapeutic potential of this ion in orthopedics.

Activation of the epithelial Na + channel triggers prostaglandin E 2 release and production required for embryo implantation

Embryo implantation remains a poorly understood process. We demonstrate here that activation of the epithelial Na+ channel (ENaC) in mouse endometrial epithelial cells by an embryo-released serine protease, trypsin, triggers Ca2+ influx that leads to prostaglandin E2 (PGE2) release, phosphorylation of the transcription factor CREB and upregulation of cyclooxygenase 2, the enzyme required for prostaglandin production and implantation. We detected maximum ENaC activation, as indicated by ENaC cleavage, at the time of implantation in mice. Blocking or knocking down uterine ENaC in mice resulted in implantation failure. Furthermore, we found that uterine ENaC expression before in vitro fertilization (IVF) treatment is markedly lower in women with implantation failure as compared to those with successful pregnancy. These results indicate a previously undefined role of ENaC in regulating the PGE2 production and release required for embryo implantation, defects that may be a cause of miscarriage and low success rates in IVF.

Distribution and regulation of ENaC subunit and CFTR mRNA expression in murine female reproductive tract

The present study investigated the regional distribution and cyclic changes in the mRNA expression of epithelial Na+ channel (ENaC) subunit and cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated Cl- channel, in adult female mouse reproductive tract. In situ hybridization revealed that in contrast to the abundant expression of CFTR, ENaC (alpha, beta, gamma) mRNA signal was not detected throughout the estrus cycle in the ovary and oviduct. Messenger RNA for all ENaC subunits was abundantly detected in the cervical and vaginal epithelia throughout the estrus cycle but for CFTR, mRNA was found only at proestrus. In the uterine epithelium, alphaENaC mRNA was detected at diestrus but not found at any other stage, while CFTR mRNA was only detected at early estrus but not other stages. Semi-quantitative RT-PCR detected mRNA for all ENaC subunits in the uterus throughout the cycle with maximal expression at diestrus and CFTR mRNA was only found in the early stages of the cycle. The involvement of ENaC and CFTR in Na+ absorption and Cl- secretion was demonstrated in cultured endometrial epithelia using the short-circuit current technique and found to be influenced by ovarian hormones. Taken together, these data indicate a main secretory role of the ovary and oviduct and a predominantly absorptive role of the cervix and vagina. The present results also suggest an ability of the uterus to secrete and absorb at different stages of the estrus cycle. Variations in the fluid profiles may be dictated by the regional and cyclic variations in expression of ENaC and CFTR and are likely to contribute to various reproductive events in different regions of the female reproductive tract.

Morin hydrate: a potential antioxidant in minimizing the free-radicals-mediated damage to cardiovascular cells by anti-tumor drugs.

The co-incubation of morin hydrate with either doxorubicin or mitomycin C could minimize the toxicity of these anti-tumor drugs on cardiovascular cells, such as red blood cells, human umbilical vein endothelial cells (ECV304) and primary mouse cardiomyocytes, whereas morin hydrate did not lower the cytotoxicity of the drugs on human hepatocellular carcinoma cells (HepG2). Morin hydrate may not exert its antioxidant effect by enhancing the antioxidant enzymatic activity because it did not cause any induction on the mRNA levels of manganese superoxide dismutase expression in ECV304 cells and HepG2 cells.

Glucose-induced electrical activities and insulin secretion in pancreatic islet β-cells are modulated by CFTR

The cause of insulin insufficiency remains unknown in many diabetic cases. Up to 50% adult patients with cystic fibrosis (CF), a disease caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR), develop CF-related diabetes (CFRD) with most patients exhibiting insulin insufficiency. Here we show that CFTR is a regulator of glucose-dependent electrical acitivities and insulin secretion in β-cells. We demonstrate that glucose elicited whole-cell currents, membrane depolarization, electrical bursts or action potentials, Ca2+ oscillations and insulin secretion are abolished or reduced by inhibitors or knockdown of CFTR in primary mouse β-cells or RINm5F β-cell line, or significantly attenuated in CFTR mutant (DF508) mice compared with wild-type mice. VX-809, a newly discovered corrector of DF508 mutation, successfully rescues the defects in DF508 β-cells. Our results reveal a role of CFTR in glucose-induced electrical activities and insulin secretion in β-cells, shed light on the pathogenesis of CFRD and possibly other idiopathic diabetes, and present a potential treatment strategy.