Subfatin is a novel adipokine and unlike meteorin in adipose and brain expression

Aim Adipose tissue releases adipokines that play important roles in metabolic and cardiocerebro- vascu- lar homeostasis. This study was to discover novel adipokines using caloric restriction model. Methods Adipokine candidates were captured by gene array and bioinformatics analysis and verified by preparation of recombinant pro- tein and antibody. Results We established a potential secreted protein database containing 208 genes and identi- fied a novel adipokine, Subfatin, that was the highest expressed in subcutaneous fat of both rodents and humans a- mong 15 detected tissues. The secreted mammalian Subfatin was a glycosylated protein. Subfatin was located dif- fusely throughout the adipose tissue except lipid droplets, with comparable expression between adipocytes and stro- real cells, but much lower expression in macrophages than adipocytes. Subfatin was downregulated in white adipose tissue of caloric restriction rats, whereas dramatically upregulated during white adipocyte differentiation as well as in white adipose tissue of diet-induced obese mice. Subfatin was annotated as Meteorin-like （Metrnl） in public data- bases, a similar transcript of Meteorin （Metrn, also known as glial cell differentiation regulator）. Meteorin dis- played a brain-specific expression and was scarce in various adipose tissues, in contrast to the tissue expression pat- terns of Subfatin. Conclusions Subfatin is a novel adipokine regulated by adipogenesis and obesity, with tissue distribution different from its homologue Meteorin.