Search

WISP1 (Wnt1-inducible signaling pathway protein-1, also known as CCN4) is a member of the secreted extracellular matrix-associated proteins of the CCN family and a target gene of the Wingless-type (WNT) signaling pathway. Growing evidence links the WNT signaling pathway to the regulation of adipogenesis and low-grade inflammation in obesity. We aimed to validate WISP1 as a novel adipokine. Human adipocyte differentiation was associated with increased WISP1 expression and secretion. Stimulation of human macrophages with WISP1 led to a proinflammatory response. Circulating WISP1 and WISP1 subcutaneous adipose tissue expression were regulated by weight changes in humans and mice. WISP1 expression in visceral and subcutaneous fat tissue was associated with markers of insulin resistance and inflammation in glucose-tolerant subjects. In patients with nonalcoholic fatty liver disease, we found no correlation among disease activity score, liver fat content, and WISP1 expression. Insulin regulated WISP1 expression in adipocytes in vitro but had no acute effect on WISP1 gene expression in subcutaneous fat tissue in overweight subjects who had undergone hyperinsulinemic clamp experiments. The data suggest that WISP1 may play a role in linking obesity to inflammation and insulin resistance and could be a novel therapeutic target for obesity. [ABSTRACT FROM AUTHOR]

Reduced expression of the INDY (I'm not dead yet) tricarboxylate carrier increased life span in different species by mechanisms akin to caloric restriction. The mammalian INDY homolog (mIndy) gene expression seems to be regulated by hormonal and/or nutritional factors. The underlying mechanisms are still unknown. The current study revealed that mIndy expression and [14C]-citrate uptake was induced by physiological concentrations of glucagon via a cAMP- and cAMP-responsive-element-binding protein (CREB)-dependent mechanism in primary rat hepatocytes. The promoter sequence of mIndy located upstream of the most frequent transcription start site was determined by 5'-race. In silico analysis identified a CREB-binding site within this promoter fragment of mIndy. Functional relevance for the CREB-binding site was demonstrated with reporter gene constructs, which were induced by CREB activation when under the control of a fragment of wild type promoter whereas promoter activity was lost after site directed mutagenesis of the CREB-binding site. Moreover, CREB binding to this promoter element was confirmed by chromatin immunoprecipiation in rat liver. In vivo studies revealed that mIndy was induced in livers of fasted as well as HFD-streptozotocin-diabetic rats, in which CREB is constitutively activated. mIndy induction was completely prevented when CREB was depleted in these rats by antisense oligonucleotides. Together, these data suggest that mIndy is a CREB-dependent glucagon target gene, which is induced in fasting and in type 2 diabetes. Increased mINDY expression might contribute to the metabolic consequences of diabetes in the liver. [ABSTRACT FROM AUTHOR]