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Box Transcription Factor (box + transcription_factor)
Selected AbstractsAging does not reduce the hepatocyte proliferative response of mice to the primary mitogen TCPOBOPHEPATOLOGY, Issue 4 2004Giovanna M. Ledda-Columbano It has been shown that the magnitude of DNA synthesis and the time at which maximal DNA synthesis occurs after two-thirds partial hepatectomy (PH) is greatly reduced in the liver of aged rodents compared to young animals. This reduction could represent an intrinsic defect in proliferation or a more specialized change in the response to PH. We therefore evaluated the proliferative capacity of hepatocytes in aged animals, following treatment with primary liver mitogens. We show that treatment of 12-month-old CD-1 mice with the hepatomitogen 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) caused an increase in hepatocyte proliferation similar to that seen in young (8-week-old) mice. The labeling index was 82% in the livers of aged mice versus 76% in young animals. Histological observation demonstrated that the number of hepatocytes entering mitoses was similar in both groups; the mitotic indices were 2.5 per thousand and 2.7 per thousand, respectively. Additional experiments showed that the timing of DNA synthesis and M phase were nearly identical in both aged and young mice. Stimulation of hepatocyte DNA synthesis was associated with increased expression of several cell cycle-associated proteins (cyclin D1, cyclin A, cyclin B1, E2F, pRb, and p107); all were comparable in aged mice and young mice. TCPOBOP treatment also increased expression of the Forkhead Box transcription factor m1b (Foxm 1b) to a similar degree in both groups. In conclusion, hepatocytes retain their proliferative capacity in old age despite impaired liver regeneration. These findings suggest that therapeutic use of mitogens would alleviate the reduction in hepatocyte proliferation observed in the elderly. (Hepatology 2000;40:981,988). [source] IL-27 controls the development of inducible regulatory T cells and Th17 cells via differential effects on STAT1EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2007Clemens Neufert Abstract IL-27 is an IL-12-related cytokine frequently present at sites of inflammation that can promote both anti- and pro-inflammatory immune responses. Here, we have analyzed the mechanisms how IL-27 may drive such divergent immune responses. While IL-27 suppressed the development of proinflammatory Th17 cells, a novel role for this cytokine in inhibiting the development of anti-inflammatory, inducible regulatory T cells (iTreg) was identified. In fact, IL-27 suppressed the development of adaptive, TGF-,-induced Forkhead box transcription factor p3-positive (Foxp3+) Treg. Whereas the blockade of Th17 development was dependent on the transcription factor STAT1, the suppression of iTreg development was STAT1 independent, suggesting that IL-27 utilizes different signaling pathways to shape T cell-driven immune responses. Our data thus demonstrate that IL-27 controls the development of Th17 and iTreg cells via differential effects on STAT1. [source] mRNA metabolism of flowering-time regulators in wild-type Arabidopsis revealed by a nuclear cap binding protein mutant, abh1THE PLANT JOURNAL, Issue 6 2007Josef M. Kuhn Summary The precise regulation of RNA metabolism has crucial roles in numerous developmental and physiological processes such as the induction of flowering in plants. Here we report the identification of processes associated with mRNA metabolism of flowering-time regulators in wild-type Arabidopsis plants, which were revealed by an early flowering mutation, abh1, in an Arabidopsis nuclear mRNA cap-binding protein. By using abh1 as an enhancer of mRNA metabolism events, we identify non-coding polyadenylated cis natural antisense transcripts (cis-NATs) at the CONSTANS locus in wild-type plants. Our analyses also reveal a regulatory function of FLC intron 1 during transcript maturation in wild type. Moreover, transcripts encoding the FLM MADS box transcription factor are subject to premature intronic polyadenylation in wild type. In each case, abh1 showed altered patterns in RNA metabolism in these events compared with wild type. Together, abh1 enhances steps in the RNA metabolism that allowed us to identify novel molecular events of three key flowering-time regulators in wild-type plants, delivering important insights for further dissecting RNA-based mechanisms regulating flowering time in Arabidopsis. [source] Generation of mice harboring a Sox6 conditional null allele,GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 5 2006Bogdan Dumitriu Abstract Sox6 belongs to the family of Sry-related HMG box transcription factors, which determine cell fate and differentiation in various lineages. Sox6 is expressed in several tissues, including cartilage, testis, neuronal, and erythropoietic tissues. Mice lacking Sox6 have revealed critical roles for Sox6 in several of these tissues, but their multiple defects and early lethality has limited studies in specific cell types and in postnatal mice. We show here that we have generated mice harboring a Sox6 conditional null allele (Sox6fl+) by flanking the second coding exon with loxP sites. This allele encodes wildtype Sox6 protein, is expressed normally, and is efficiently converted into a null allele (Sox6fl,) by Cre-mediated recombination in somatic and germ cells. Sox6fl+/fl+ mice are indistinguishable from wildtype mice, and Sox6fl,/fl, mice from Sox6,/, mice. These Sox6 conditional null mice will thus be valuable for further uncovering the roles of Sox6 in various processes in vivo. genesis 44:219,224, 2006. Published 2006 Wiley-Liss, Inc. [source] | |||||||||||||