Proteomic Analysis of adipose tissue derived Exosome-like vesicles

Scope: Adipose tissue is regarded as a true endocrine organ. Recent studies showed that adipose tissue derived exosomes could serve as carrier of circulating miRNAs to regulate distant targets. However, the characteristics of exosomal proteins released from adipose tissue have not been investigated yet. Methods and Results: In this study, we conducted a complementary protein profiling on exosome-like vesicles derived from adipose tissue (ELV-AT) with Label-free Quantitative Proteomic Analysis. A total of 3229 ELV-AT proteins were identified, among which only 266 proteins have been annotated as adipokines. 3 undefined adipokine candidates (NPM3, STEAP3, and DAD1) were selected for further validation. These 3 proteins were expressed in both white and brown adipose tissue, upregulated during adipogenic differentiation of both 3T3-L1 cells and adipose derived stem cells (ADSCs). Expressions of NPM3, DAD1 in ELV-AT were significantly decreased in obese subjects compared with lean controls while obesity could not alter the expression of STEAP3. Conclusions: Our profiling study of the ELV-AT proteins expands the list of adipokines and highlights the pivotal role of exosomal adipokines in the regulation of multiple biological processes within adipose tissue