The selective continued linkage of centromeres from mitosis to interphase in the absence of mammalian separase

Separase is an evolutionarily conserved protease that is essential for chromosome segregation and cleaves cohesin Scc1/Rad21, which joins the sister chromatids together. Although mammalian separase also functions in chromosome segregation, our understanding of this process in mammals is still incomplete. We generated separase knockout mice, reporting an essential function for mammalian separase. Separase-deficient mouse embryonic fibroblasts exhibited severely restrained increases in cell number, polyploid chromosomes, and amplified centrosomes. Chromosome spreads demonstrated that multiple chromosomes connected to a centromeric region. Live observation demonstrated that the chromosomes of separase-deficient cells condensed, but failed to segregate, although subsequent cytokinesis and chromosome decondensation proceeded normally. These results establish that mammalian separase is essential for the separation of centromeres, but not of the arm regions of chromosomes. Other cell cycle events, such as mitotic exit, DNA replication, and centrosome duplication appear to occur normally. We also demonstrated that heterozygous separase-deficient cells exhibited severely restrained increases in cell number with apparently normal mitosis in the absence of securin, which is an inhibitory partner of separase

18. asırda "Hırkai şerif" ziyareti

Taha Toros Arşivi, Dosya No: 120-Saraylar. Not: Gazetenin "Tarihten Sahifeler" köşesinde yayımlanmıştır.İstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Hexokinase 2 in colorectal cancer: a potent prognostic factor associated with glycolysis, proliferation and migration

Background. It is well known that proliferating carcinoma cells preferentially use aerobic glycolysis rather than oxidative phosphorylation for energy production. Hexokinase 2 (HK2) plays a pivotal role in the glycolytic pathway. Previous studies have demonstrated that HK2 activity is markedly increased in various malignant neoplasms, but the clinical and biological significance of HK2 remain largely unclear in the colorectal carcinoma. Patients and methods. We performed immunohistochemistry for HK2 in 195 colorectal carcinoma tissues. We also used HCT8 and HT29 colon carcinoma cells in in vitro studies. Results. HK2 immunoreactivity was detected in 100 out of 195 (51%) colorectal carcinoma tissues, and the immunohistochemical HK2 status was significantly associated with tumor size, depth of invasion, liver metastasis and TNM stage in these cases. Moreover, the HK2 status was significantly associated with increased incidence of recurrence and overall mortality of the patients, and multivariate analyses demonstrated that HK2 status was an independent prognostic factor for both disease-free and overall survival. Subsequent in vitro experiments revealed that both HCT8 and HT29 colon carcinoma cells transfected with specific siRNA for HK2 significantly decreased the lactate production, proliferation activity and migration property. Conclusion. These results suggest that HK2 plays important roles in the glycolytic, proliferation and migration properties of colorectal carcinoma and, therefore, HK2 status is a potent worse prognostic factor in colorectal cancer patient