Multiple roles of PPARα in brown adipose tissue under constitutive and cold conditions

Abstract

Peroxisome proliferator-activated receptor α (PPARα) is a member of the nuclear receptor family, regulating fatty acid degradation in many organs. Two-dimensional SDS-PAGE of brown adipose tissue (BAT) from PPARα-null mice produced a higher-density spot. Proteomic analysis indicated that the protein was pyruvate dehydrogenase β (PDHβ). To observe PDHβ regulation in BAT, the organ was stimulated by long-term cold exposure, and the activities of associated enzymes were investigated. Histological and biochemical analyses of BAT showed a significant decrease in the triglyceride content in wild-type mice and some degree of decrease in PPARα-null mice on cold exposure. Analyses of molecules related to glucose metabolism showed that the expression of PDHβ is under PPARα-specific regulation, and that glucose degradation ability may decrease on cold exposure. In contrast, analyses of molecules related to fatty acid metabolism showed that numerous PPARα/γ target molecules are induced on cold exposure, and that fatty acid degradation ability in wild-type mice is markedly enhanced and also increases to same degree in PPARα-null mice on cold exposure. Thus, this study proposes novel and multiple roles of PPARα in BAT. © 2009 The Authors. Journal compilation © 2009 by the Molecular Biology Society of Japan/Blackwell Publishing Ltd.