EFFECT OF BETA-ADRENERGIC STIMULATION ON HUMAN iPSC-DERIVED ENGINEERED MUSCLE TISSUES CARRYING EITHER SOD1-G93A OR TARDBP/TDP-43 Q331K MUTATION

• Grant number: 25/04777-7
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Julio Cesar Batista Ferreira
• Grantee: Lisley Santos Ramalho
• Supervisor: Alexander Simon Tulloch Smith
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: University of Washington, United States
• Associated to the scholarship: 22/08635-4 - Role of the Sympathetic Nervous System in Amyotrophic Lateral Sclerosis (ALS), BP.DR

Abstract

Amyotrophic lateral sclerosis (ALS) is a terminal neurodegenerative disease characterized by skeletal muscle atrophy, paralysis, and death due to progressive loss of both upper and lower (cortical and spinal) motor neurons. A key pathological feature of both sporadic and familial ALS is the cytoplasmic mislocalization and aggregation of proteins such as SOD1 and TDP-43. Often underestimated, dysautonomia has been reported in ALS patients.However, its contribution to the onset and progression of ALS remains poorly understood. Our preliminary findings demonstrate that ALS mice carrying the SOD1-G93A mutation exhibit dysautonomia, characterized by increased sympathetic tone, decreased parasympathetic tone, and elevated skeletal muscle and circulatingnorepinephrine levels at late stages compared to controls. As proof of concept, either sustained administration of isoproterenol or genetic induction of sympathetic hyperactivity accelerates ALS symptoms in SOD1-G93A mutant mice. Interestingly, sustained adrenergic stimulation causes skeletal muscle hypertrophy in WT but not in ALS mice. These findings suggest that lack of skeletal muscle response to adrenergic stimulation in ALS mice is caused, at least in part, by dysautonomia-induced massive downregulation of beta-adrenergic receptors in skeletal muscle.Considering that skeletal muscle presents a high density of beta-adrenergic receptors (mainly beta-2 subtype), which seems to be severely affected in ALS, we propose to explore the functional, morphological and biochemical consequences of sustained adrenergic stimulation in human iPSC-derived engineered muscle tissues (EMTs).Specifically, we will investigate whether the presence of the CRISPR edited SOD1-G93A mutation impairs the response of human iPSC-derived engineered muscle tissues to sustained adrenergic stimulation. These findings will be validated using another TARDBP/TDP-43 Q331K mutation also associated with ALS in humans. We hypothesize that sustained adrenergic stimulation will desensitize beta-2 adrenergic receptors in human iPSCderived EMTs carrying either SOD1-G93A or TARDBP/TDP-43 Q331K mutation, but not in wild-type; therefore, blunting the activation of pro-survival pathways and beneficial tissue remodeling linked to beta-2 adrenergic receptors activation. Our findings will provide new insights into the skeletal muscle role of adrenergic stimulation in ALS; therefore, contributing to the development/validation of novel targets and therapeutic strategies to treat ALS. (AU)