Showing papers by "Yoichi Shinkai published in 2006"
TL;DR: Genetic studies show that epigenetic changes actually have an important role in the inhibition of Oct-3/4 re-expression, thereby preventing reprogramming.
Abstract: Oct-3/4 is a POU domain homeobox gene that is expressed during gametogenesis and in early embryonic cells, where it has been shown to be important for maintaining pluripotency. Following implantation, this gene undergoes a novel multi-step programme of inactivation. Transcriptional repression is followed by a pronounced increase in histone H3 methylation on Lys 9 that is mediated by the SET-containing protein, G9a. This step sets the stage for local heterochromatinization via the binding of HP1 and is required for subsequent de novo methylation at the promoter by the enzymes Dnmt3a/3b. Genetic studies show that these epigenetic changes actually have an important role in the inhibition of Oct-3/4 re-expression, thereby preventing reprogramming.
679 citations
TL;DR: It is shown that T BP‐2 expression is markedly up‐regulated during fasting in wild‐type mice, while TBP‐2−/− mice were predisposed to death with bleeding tendency, as well as hepatic and renal dysfunction as a result of 48 h of fasting.
Abstract: Thioredoxin binding protein-2 (TBP-2) is a negative regulator of thioredoxin and has multiple regulatory functions in cellular redox, growth, differentiation, apoptosis, and aging. To investigate the function of TBP-2 in vivo, we generated mice with targeted inactivation of TBP-2 (TBP-2-/- mice). Here, we show that TBP-2 expression is markedly up-regulated during fasting in wild-type mice, while TBP-2-/- mice were predisposed to death with bleeding tendency, as well as hepatic and renal dysfunction as a result of 48 h of fasting. The fasting-induced death was rescued by supplementation of glucose but not by that of oleic acid, suggesting that inability of fatty acid utilization plays an important role in the anomaly of TBP-2-/- mice. In these mice, plasma free fatty acids levels are higher, whereas glucose levels are lower than those of wild-type mice. Compared with wild-type mice, TBP-2-/- mice showed increased levels of plasma ketone bodies, pyruvate and lactate, indicating that Krebs cycle-mediated fatty acid utilization is impaired. Because the fatal impairment of fatty acid utilization is a characteristically metabolic feature of Reye (-like) syndrome, TBP-2-/- mouse may represent a novel model for investigating the pathophysiology of these disorders.
121 citations
TL;DR: Data indicate that Wiz not only contributes to the stability of G9a but also links the G 9a/GLP heteromeric complex to the CtBP co-repressor machinery.
119 citations
TL;DR: This method should be useful for future production of knockouts of multiple genes in livestock and is faster and more economical than backcrossing to produce homozygous knockouts.
Abstract: BACKGROUND Gene targeting in large animals has the potential to be useful in medicine as well as in agriculture. Previously, we reported the first successful targeting of the bovine alpha1,3-galactosyltransferase (alpha1,3GT) gene and establishment of a heterozygous knockout cell line. In this report, we generated both heterozygous and homozygous knockout bovine cell lines, and alpha1,3GT-gene knockout cattle. METHODS alpha1,3GT gene-disruption was accomplished using primary fetal fibroblasts with a single targeting vector, a promoter-less positive selection vector containing IRES (internal ribosome entry site)-antibiotic-resistance gene (neo) cassette and loxP sequences. At each step in establishing heterozygous and homozygous knockout cell lines, the antibiotic-resistance gene cassette in the targeted allele was removed by a Cre-loxP recombination system that utilizes an adenovirus with transient Cre recombinase expression. A nuclear transfer was performed using alpha1,3GT fetal fibroblasts, and one alpha1,3GT knockout calf was generated but died shortly after birth (day 287). RESULTS Necropsy revealed normal morphology in all organs. The calf weighed 22.3 kg at birth and this value is within the normal range. CONCLUSION The alpha1,3GT knockout- and antibiotic-resistance gene free (alpha1,3GT(-/-)neo-) cells could be cloned normally. Thus, cloned cattle from alpha1,3GT(-/-) neo- cells are potentially safer for human use. Additionally, our strategy is faster and more economical than backcrossing to produce homozygous knockouts. This method should be useful for future production of knockouts of multiple genes in livestock.
21 citations
TL;DR: Although Rad54‐deficient ALT ES cells showed radiosensitivity in line with expectation, cell growth and telomeres were maintained for more than 200 cell divisions, and this is the first genetic evidence that mouse Rad54 is dispensable for the ALT pathway.
Abstract: Some immortal cells use the alternative lengthening of telomeres (ALT) pathway to maintain their telomeres instead of telomerase. Previous studies revealed that homologous recombination (HR) contributes to the ALT pathway. To further elucidate molecular mechanisms, we inactivated Rad54 involved in HR, in mouse ALT embryonic stem (ES) cells. Although Rad54-deficient ALT ES cells showed radiosensitivity in line with expectation, cell growth and telomeres were maintained for more than 200 cell divisions. Furthermore, although MMC-stimulated sister chromatid exchange (SCE) was suppressed in the Rad54-deficient ALT ES cells, ALT-associated telomere SCE was not affected. This is the first genetic evidence that mouse Rad54 is dispensable for the ALT pathway.
9 citations
Journal Article•
2 citations