Tracing transcriptomic changes to uncover unknown roles of TZDs

University Of Pennsylvania, Philadelphia PA

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Abstract

? DESCRIPTION (provided by applicant): Obesity, caused by excess calories stored as fat in white adipose tissue (WAT), is a major risk factor for metabolic disorders including type 2 diabetes. The discovery of fat-burning brown adipose tissue (BAT) in humans has raised the exciting possibility that BAT may be targeted to treat obesity and metabolic diseases. Thiazolidinediones (TZDs) can function to convert WAT into a brown-like state, and they have been used as a remedy for diabetes, but their clinical use has been limited because of serious side effects. A molecular understanding of TZD action will lead to the development of efficacious yet lower-risk drugs for metabolic disorders. In our preliminary studies, we observed widespread co-transcriptional splicing in nascent RNAs (GROseq). We found that TZDs regulate co-transcriptional splicing as well as the transcription levels of splicesomal genes. Interestingly, genes with altered co-transcriptional splicing ratios were associated with browning effect and PPAR signaling pathway. Based on these observations, we propose to study alternative splicing regulated by TZDs and determine the association with insulin sensitivity. Also, we recently found that TZDs re-distribute Med1 occupancy, a subunit of the Mediator. Interestingly, Med23, another subunit of the Mediator, regulates alternative splicing. Based on these observations, we aim to study if the mediator redistribution is associated with alternative splicing. Moreover, we further aim to study RNA stability by integrating nascent RNA (GROseq) and steady-state RNA (RNAseq). Isoforms spliced differently have different half-lives. Using a systematic way to integrate transcriptomic data we will investigate if TZDs regulate RNA stability. Our innovative approach to use nascent and steady-state RNAs will enhance our understanding of TZDs by fully exploiting the transcriptomic landscapes. The comprehensive nature of our study will reveal previously unrecognized regulatory mechanisms of TZDs in regulating alternative splicing and RNA stability. Our study will lead us to the identification of efficacious, low-risk drug targets fr the metabolic disorders that pervade society.