Angiotensinogen, adipocyte differentiation and fat mass enlargement.

PURPOSE OF REVIEW: Angiotensinogen and components of the renin-angiotensin system are expressed in adipose tissue of rodents and humans, but the role of generated angiotensin II has remained intriguing. Moreover, the functional importance of angiotensin II receptor subtypes in preadipocytes and adipocytes still remains a controversial subject. RECENT
FINDINGS: Recent findings in transgenic mice have emphasized the upregulation of angiotensinogen expression by glucocorticoids. Furthermore, angiotensinogen products, that is angiotensin II and possibly angiotensin II-related products, have been found to act locally in modulating adipose tissue growth in an autocrine/paracrine manner. Cellularity measurements show that fat mass enlargement is associated with adipocyte hypertrophy, consistent with the upregulation of the fatty acid synthetase gene by angiotensin II depicted at the molecular level. Together, these findings suggest a mechanism by which transient or chronic overexpression of angiotensinogen in adipose tissue favors lipogenesis in adipocytes and leads to a 'vicious' circle whereby adipose tissue development is further increased.
SUMMARY: Additional studies are warranted to characterize angiotensin II-related receptors, if any, and to clarify the role played by angiotensin II receptor subtypes and metabolites in various metabolic aspects of white adipose tissue.