Unveiling the adipose tissue contribution to the microRNA pool in distal tissues: a novel approach for extracellular microRNA tracking

• Grant number: 23/09641-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date until: November 01, 2023
• End date until: October 31, 2024
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Marcelo Alves da Silva Mori
• Grantee: Gabriel Palermo Ruiz
• Supervisor: Carl Ronald Kahn
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: Harvard University, Boston, United States
• Associated to the scholarship: 18/21635-8 - Study of the role of miR-203-3p in adipose tissue metabolism and in the pathogenesis of metabolic diseases in mice, BP.DD

Abstract

Metabolic syndrome affects 25% of the adult population, emerging as one of the largest public health concerns worldwide. Obesity, insulin resistance and impaired glucose metabolism are the main drivers of metabolic syndrome. Adipose tissue dysfunction is intimately linked to the onset of these conditions, and this is associated with the ability of adipocytes to synthesize and secrete microRNAs (miRNAs). Seminal discoveries by the Kahn lab in collaboration with the Mori lab have shown that adipose tissue is the main contributor to the circulating pool of exosomal miRNAs in mice, and that adipose tissue-derived miRNAs can regulate gene expression in distal tissues. Subsequent to these findings, several examples of cell non-autonomous mechanisms involving adipose tissue-derived miRNA have been described, highlighting the importance of such mechanisms to mediate adipose tissue's endocrine function. However, in all of these studies, the transfer of miRNAs from the adipose tissue to other tissues have only been indirectly demonstrated. Moreover, the contribution of adipose-derived miRNAs to the pool of miRNAs in a given tissue has never been determined, in part due to the lack of proper models. To address these issues, a new tool to track extracellular miRNAs in vivo in mice has been developed by the Kahn lab. The approach is based on thiol(SH)-linked alkylation of nascent RNAs by tissue-specific expression of the enzyme UPRT and by feeding mice with 4-thiouracil, followed by biotinylation of these RNAs and profiling of the labeled miRNAs in multiple organs. By directing UPRT expression to the adipocyte, the model allows measurement of adipocyte-derived miRNA levels across the body, unraveling new target tissues for miRNAs produced by adipocytes. Considering the focus of my thesis on miR-203-3p, and the demonstration that miR-203-3p is regulated in adipose tissue by several metabolic stimuli and secreted by adipocytes, we propose: i) to characterize mice with UPRT expression in adipocytes (Adipo-UPRT); ii) to profile adipocyte-derived miRNAs in multiple organs of interest in response to different metabolic challenges; and iii) use this model and other complementary models to investigate how adipocyte-derived miR-203-3p is regulated in vivo and distributed across the body. In addition to shed light onto the cell non-autonomous roles of miR-203-3p, this model will benefit and support other ongoing projects of the Mori and the Kahn labs, unveiling the contribution of adipose tissue-derived miRNAs to the pool of miRNAs in any tissue of interest. (AU)