Study Of The Subcellular Localization And Function Of AIDA In Brown Adipocytes

Brown adipose tissue(BAT)is an important organ for maintaining body temperature and energy balance in mammals.Activated BAT could rapidly oxidize stored fat and generate heat through UCP1.The metabolic rate of the body is concurrently increased.AIDA is a protein containing a C2 domain,which enables AIDA to locate on the cell membrane.Previous studies of our lab have shown that AIDA inhibits the dietary fat absorption in the small intestine of mice,thereby preventing high-fat diet-induced obesity.However,there is little knowledge about the properties and functions of AIDA in the other tissues.According to our data on the tissue distribution of AIDA in mice,AIDA is abundantly expressed in BAT.Therefore,we focus on the BAT expressed AIDA in this thesis,we show that AIDA locates at the outer membrane of mitochondria by means of subcellular fractionation and Digitoninmediated permeabilization of mitochondrial membrane.Analysis of AIDA-associated organelles and APEX2 electron microscopy imaging experiments further demonstrate that the translocation of AIDA from the outer membrane to the intermembrane space of mitochondria in brown adipocytes is dependent on the phosphorylation of AIDA at serine 161.Finally,we investigated the biological function of AIDA in BAT via generating Aida brown adipocyte-specific knockout(Aida-BKO)mice.It was shown that the loss of AIDA in BAT did not lead to obesity of mice under normal conditions.In response to cold stress,phosphorylated AIDA by PKA translocates from the outer membrane to the intermembrane space of mitochondria to promote non-shivering thermogenesis in brown adipocytes.These findings provide a basis for further investigation of the spatiotemporal distribution of AIDA at the subcellular level and its physiological and pathological significance.