Abstract 19727: ROCK2 Mediates Browning of White Fat and Protects Against Obesity
Background: The Rho-activated kinases (ROCK1 and ROCK2) are serine threonine kinases that are ubiquitously expressed with higher levels of ROCK2 compared to ROCK1 in adipocytes. Recent studies suggest that ROCK2 may be an important regulator of energy metabolism and obesity. However, its role in adipocyte development and function is unknown.
Methods and Result: To determine the role of ROCK2 in adipocyte development and obesity, we generated adipocyte-specific deletion (ROCK2adipoQ-/-) and overexpression (CA-ROCKadipoQ+/+) of ROCK2 in mice. Compared to control mice, CA-ROCKadipoQ+/+ mice exhibited increased browning of inguinal white adipose tissue (iWAT). Indeed, immunohistochemical staining of iWAT in CA-ROCKadipoQ+/+ mice showed that UCP1 was upregulated. Furthermore, CA-ROCKadipoQ+/+ mice on high fat diet were resistant to weight gain and obesity for up to 18 weeks. This is in contrast to ROCK2adipoQ-/- mice, which developed more weight gain or obesity than control mice. To determine the physiological effects of ROCK2 on browning of iWAT, control and ROCK2adipoQ-/- mice were exposed to 4°C for 1 week. In control mice, cold exposure increased ROCK2 activity and lead to browning of iWAT. However, the iWAT in ROCK2adipoQ-/- mice failed to undergo browning. Analysis of gene expression in iWAT demonstrated increased UCP1 and mitochondria proteins in control but not ROCK2adipoQ-/- mice. Thermal imaging revealed that ROCK2adipoQ-/- mice were unable to maintain basal body temperature after prolonged cold exposure. In contrast, the heat map of the CA-ROCKadipoQ+/+ mice showed an elevation of body temperature, particularly in areas of iWAT as compared to that of control littermates.
Conclusions: ROCK2 mediates the “browning” of white adipocytes and prevents the development of obesity through increased thermogenesis. These findings suggest that the activation of ROCK2 in adipocytes may have therapeutic benefits in preventing diet-induced obesity.
Author Disclosures: P. Chen: None. C. Park: None. E. Karrar: None. C. Wang: None. J. Liao: Consultant/Advisory Board; Modest; consultancy for Asahi-Kasei Pharmaceuticals, Celgene, and Sanofi-Aventis.
This research has received full or partial funding support from the American Heart Association.
- © 2014 by American Heart Association, Inc.