Mechanistic Insights into Org 43553-Induced Energy Expenditure In Vitro

Overview

The obesity epidemic, a leading driver of chronic diseases such as cardiovascular disease and type II diabetes, remains inadequately addressed by current pharmacological treatments. GLP-1 agonists, while effective in appetite suppression, frequently cause adverse side effects, including significant lean mass loss, underscoring the need for innovative therapies. Org 43553, a low - molecular-weight agonist of the luteinizing hormone receptor (LHCGR), presents a promising alternative by selectively preventing fa t gain in vivo. This study investigates the mechanisms by which Org 43553 enhances energy expenditure in vitro, utilizing 3T3-L1 adipocytes as a model system. Our results reveal that Org 43553 significantly increases intracellular oxygen consumption rate (OCR) in a dose -dependent manner, independently of UCP1 activation, suggesting a unique pharmacologic pathway f or fat loss induction. Furthermore, Org 43553 triggers phospholipase C (PLC) activity but not cAMP production, activating a calcium - and extracellular signal-regulated kinase (ERK 1/2) -dependent signaling cascade. RNA sequencing identified ATF3 as a key upregulated transcription factor, along with its downstream targets, suggesting its potential involvement in enhancing mitochondrial activity and en ergy expenditure. The role of ATF3 was further validated with siAtf3 knockdown experiments, confirming its function as a primary driver of Org 43553 -induced changes in mitochondrial respiration. Ultimately, our findings uncover a previously uncharacterized non-canonical mechanism by which Org 43553 stimulates energy expenditure in adipose tissue, underscoring its potential as a next -generation obesity therapy and establishing a foundation for future research into targeted metabolic disease treatments.

Competition history

• JSHS 2025 Category not listed

Resources

• National JSHS abstract book ↗

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