Characterization of candidate genes for bovine adipogenesis reveals differences of TUSC5 isoforms caused by novel alternative splicing

Abstract

Different transcripts generated by alternative splicing have led to new insights to reconsider gene functions. Here, by progressively screening 31 candidate genes, we detected 3 genes that could be regulated by the peroxisome proliferator activated receptor gamma 2 (PPARG2), one isoform of the PPARG that specifically expressed in adipose tissue. Alternative splicing events of two genes regulated by PPARG2 - cell death-inducing DFFA-like effector c (CIDEC) and tumor suppressor candidate 5 (TUSC5) — were further investigated. Similar results regarding their subcellular localization were observed for two isoforms of CIDEC. We validated the existence and coding ability of a novel TUSC5 transcript (TUSC5a). Differences became apparent between the two TUSC5 transcript isoforms in terms of expression and subcellular localization, possibly caused by a 29 amino acid insertion. The expression of the TUSC5a was significantly delayed, and showed that uniquely expressed in adipose tissue and differently expressed with TUSC5b during adipocyte differentiation. Subcellular localization analyses showed that both TUSC5 isoforms existed in the endplasmic reticulum but with different localization and no interaction with CIDEC isoforms. In summary, our candidate gene-based approach provides further depth to our understanding of the process of adipogenesis, highlighting the functional diversity of one gene generated by alternative splicing.