Mitochondrial metabolic flux modulation by beta estrogen receptors in hepatocytes in response to energy overloads

• Grant number: 24/13461-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Biological Sciences - Biochemistry - Metabolism and Bioenergetics
• Principal Investigator: Alicia Juliana Kowaltowski
• Grantee: Débora Santos Rocha
• Supervisor: Maria Rohm
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: German Research Center for Environmental Health, Germany
• Associated to the scholarship: 21/04781-3 - Energy metabolism regulation by beta-type estradiol receptor in hepatocytes and adipocytes submitted to energy overload, BP.PD

Abstract

Estrogen signaling is crucial for both reproductive functions and energy metabolism. Estradiol (E2) enhances insulin production and secretion in pancreatic beta cells and insulin signaling in various tissues, including the liver. This project aims to investigate ER²'s impact on liver metabolism, a topic that remains underexplored.Postmenopausal E2 deficiency increases the risk of metabolic diseases by causing visceral adipose tissue accumulation and elevated free fatty acids (FFAs), which impair insulin sensitivity. Hormone replacement therapy (HRT) with E2 can improve adipose tissue distribution and insulin sensitivity but has potential side effects, including a higher risk of hormone-responsive cancers. In the liver, ER± primarily mediates a plenty of E2's benefits by reducing triglyceride levels and steatosis. Also, preliminary studies suggest ER² may also reduce triglyceride accumulation in hepatocytes and enhance adipose tissue distribution to a more insuline-sensitive pattern. Although ER± activation is linked to metabolic benefits, it implies cancer risks, making ER² a potentially safer target due to its antitumor indicative effects.Mitochondrial effects of ER² activation are still under elucidation. Preliminary studies indicate ER² may enhance mitochondrial respiratory capacity and biogenesis. Considering this and, given the growing issues of obesity and aging, research ER²'s role in hepatocytes could reveal new therapeutic approaches.Our findings indicate that selective activation of ER² does not significantly alter the metabolic steady-state in hepatocytes. However, ER² activation does modify the hepatocytes response to metabolic challenges. Since the liver affects the metabolism of carbohydrates, lipids, and proteins, this could impact various tissues, including the endocrine pancreas and adipose tissue. Animal studies are ongoing to explore these effects.To further understand ER²'s metabolic impact, analyzing the metabolome and using dynamic metabolic flux analysis with stable isotopic tracers (13C) is planned. This method, that is not widespread in our research centers but is used internationally, will provide detailed insights into carbon fluxes that are promoting these metabolic outcomes. Collaboration with Dr. Maria Rohm's lab, who has expertise in the evaluation of metabolic diseases, focusing on the metabolism of carbohydrates and lipids, as well as experience in fluxomics analysis, will support this advanced analysis.AML12 cells will be treated for 24h with vehicle or diarilpropionitrile (ER² agonist) in control or energy overloading media (high glucose plus palmitate). The first experimental approach will assess the chronic effects of ER² activation on intact-cell and isolated mitochondrial. The second experiment will evaluate metabolic flexibility by stimulating cells with epinephrine or insulin after 24 hours of treatment. Fluxomic analysis will measure the response to these stimuli. Additionally, pharmacological modulators will be used to alter key enzyme activities to investigate their impact on pyruvate and fatty acid oxidation.