Nanog protein is expressed in the interior cells of compacted morulae and maintained till epiblasts but downregulated by implantation stage. It is also expressed in embryonic stem cells, embryonic carcinoma cells and ...Nanog protein is expressed in the interior cells of compacted morulae and maintained till epiblasts but downregulated by implantation stage. It is also expressed in embryonic stem cells, embryonic carcinoma cells and embryonic germ cells but disappeared in differentiated ES cells. In this study, we have isolated, sequenced, and performed the first characterization of the Nanog promoter. The transcription start sites were mapped by primer extension analysis. Two promoter regions were found upstream the transcription start sites and the expression of major Nanog promoter/ reporter gene construct is abolished in differentiated F9 EC cells as compared to the undifferentiated counterpart. We also showed that a putative octamer motif (ATGCAAAA) is necessary for the major promoter activity. Gel shift and supershift assays showed that Oct-1, Oct-4 and Oct-6 protein selectively bind to the octamer motif.展开更多
Insulin can stimulate hepatic expression of carbohydrate-responsive element-binding protein （ChREBP）. As recent studies revealed potential metabolic beneficial effects of ChREBP, we asked whether its expression can ...Insulin can stimulate hepatic expression of carbohydrate-responsive element-binding protein （ChREBP）. As recent studies revealed potential metabolic beneficial effects of ChREBP, we asked whether its expression can also be regulated by the dietary polyphenoi curcumin. We also aimed to determine mechanisms underlying ChREBP stimulation by insulin and curcumin. The effect of insulin on ChREBP expression was assessed in mouse hepatocytes, while the effect of curcumin was assessed in mouse hepatocytes and with curcumin garage in mice. Chemical inhibitors for insulin signaling molecules were utilized to identify involved signaling molecules, and the involvement of p21-activated protein kinase 1 （Pakl） was determined with its chemical inhibitor and Pokl-/- hepatocytes. We found that both insulin and curcumin-stimulated ChREBP expression in Akt-independent but MEK/ERK-dependent manner, involving the inactivation of the transcriptional repressor Oct-1. Aged Pokl-/- mice showed reduced body fat volume. Pakl inhibition or its genetic deletion attenuated the stimulatory effect of insulin or curcumin on ChREBP expression. Our study hence suggests the existence of a novel signaling cascade Pakl/MEK/ERK/Oct-1 for both insulin and curcumin in exerting their glucose-lowering effect via promoting hepatic ChREBP production, supports the recognition of beneficial functions of ChREBP, and brings us a new overview on dietary polyphenols.展开更多
文摘Nanog protein is expressed in the interior cells of compacted morulae and maintained till epiblasts but downregulated by implantation stage. It is also expressed in embryonic stem cells, embryonic carcinoma cells and embryonic germ cells but disappeared in differentiated ES cells. In this study, we have isolated, sequenced, and performed the first characterization of the Nanog promoter. The transcription start sites were mapped by primer extension analysis. Two promoter regions were found upstream the transcription start sites and the expression of major Nanog promoter/ reporter gene construct is abolished in differentiated F9 EC cells as compared to the undifferentiated counterpart. We also showed that a putative octamer motif (ATGCAAAA) is necessary for the major promoter activity. Gel shift and supershift assays showed that Oct-1, Oct-4 and Oct-6 protein selectively bind to the octamer motif.
文摘Insulin can stimulate hepatic expression of carbohydrate-responsive element-binding protein （ChREBP）. As recent studies revealed potential metabolic beneficial effects of ChREBP, we asked whether its expression can also be regulated by the dietary polyphenoi curcumin. We also aimed to determine mechanisms underlying ChREBP stimulation by insulin and curcumin. The effect of insulin on ChREBP expression was assessed in mouse hepatocytes, while the effect of curcumin was assessed in mouse hepatocytes and with curcumin garage in mice. Chemical inhibitors for insulin signaling molecules were utilized to identify involved signaling molecules, and the involvement of p21-activated protein kinase 1 （Pakl） was determined with its chemical inhibitor and Pokl-/- hepatocytes. We found that both insulin and curcumin-stimulated ChREBP expression in Akt-independent but MEK/ERK-dependent manner, involving the inactivation of the transcriptional repressor Oct-1. Aged Pokl-/- mice showed reduced body fat volume. Pakl inhibition or its genetic deletion attenuated the stimulatory effect of insulin or curcumin on ChREBP expression. Our study hence suggests the existence of a novel signaling cascade Pakl/MEK/ERK/Oct-1 for both insulin and curcumin in exerting their glucose-lowering effect via promoting hepatic ChREBP production, supports the recognition of beneficial functions of ChREBP, and brings us a new overview on dietary polyphenols.
