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Apelin, a newly identified adipokine up-regulated by insulin and obesity.
- Source :
-
Endocrinology [Endocrinology] 2005 Apr; Vol. 146 (4), pp. 1764-71. Date of Electronic Publication: 2005 Jan 27. - Publication Year :
- 2005
-
Abstract
- The results presented herein demonstrate that apelin is expressed and secreted by both human and mouse adipocytes. Apelin mRNA levels in isolated adipocytes are close to other cell types present in white adipose tissue or other organs known to express apelin such as kidney, heart, and to a lesser extent brown adipose tissue. Apelin expression is increased during adipocyte differentiation stage. A comparison of four different models of obesity in mice showed a large increase in both apelin expression in fat cells and apelin plasma levels in all the hyperinsulinemia-associated obesities and clearly demonstrated that obesity or high-fat feeding are not the main determinants of the rise of apelin expression. The lack of insulin in streptozotocin-treated mice is associated with a decreased expression of apelin in adipocytes. Furthermore, apelin expression in fat cells is strongly inhibited by fasting and recovered after refeeding, in a similar way to insulin. A direct regulation of apelin expression by insulin is observed in both human and mouse adipocytes and clearly associated with the stimulation of phosphatidylinositol 3-kinase, protein kinase C, and MAPK. These data provide evidence that insulin exerts a direct control on apelin gene expression in adipocytes. In obese patients, both plasma apelin and insulin levels were significantly higher, suggesting that the regulation of apelin by insulin could influence blood concentrations of apelin. The present work identifies apelin as a novel adipocyte endocrine secretion and focuses on its potential link with obesity-associated variations of insulin sensitivity status.
- Subjects :
- Adipocytes cytology
Adipocytes metabolism
Adipokines
Adipose Tissue metabolism
Animals
Apelin
Carrier Proteins physiology
Cell Differentiation
Female
Gene Expression Regulation
Humans
Hyperinsulinism metabolism
Insulin blood
Intercellular Signaling Peptides and Proteins
Mice
Mice, Inbred C57BL
Up-Regulation
Carrier Proteins genetics
Insulin pharmacology
Obesity metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0013-7227
- Volume :
- 146
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Endocrinology
- Publication Type :
- Academic Journal
- Accession number :
- 15677759
- Full Text :
- https://doi.org/10.1210/en.2004-1427