Evaluating pharmacological targeting of actin regulatory pathways during aging in C. elegans

Actin is a highly conserved cytoskeletal protein that regulates numerous cellular processes essential for tissue homeostasis and healthy aging. Although genetic studies have established important roles for actin and actin-binding proteins in longevity, pharmacological approaches offer complementary advantages for manipulating conserved cytoskeletal pathways across model systems. Here, we systematically evaluated the effects of small-molecule modulators targeting distinct actin regulatory pathways on lifespan, locomotor function, and tissue-specific actin organization in Caenorhabditis elegans. Animals were treated with compounds targeting the Arp2/3 complex (CK666), tropomyosin-dependent actin regulation (TR100), formins (SMIFH2), cofilin regulation (SZ-3), or actin stabilization (phalloidin). Among the compounds tested, only CK666 consistently produced a dose-dependent reduction in lifespan and exacerbated age-associated muscle actin disorganization, identifying Arp2/3-mediated actin branching as a critical regulator of cytoskeletal integrity during aging. CK666 also transiently disrupted hypodermal actin organization early in adulthood. In contrast, SMIFH2, TR100, phalloidin, and SZ-3 produced little or no detectable disruption of muscle actin organization, despite previous genetic studies demonstrating roles for several of these pathways in aging. Comparison with prior RNAi studies suggests that pharmacological perturbation can reproduce some aspects of actin dysfunction but may be limited by compound stability, drug delivery, or inefficient targeting of proteins in C. elegans. Together, these findings establish a framework for evaluating pharmacological modulation of actin during aging, identify CK666-mediated Arp2/3 inhibition as the most robust pharmacological perturbation under the conditions tested, and highlight important considerations for translating genetic discoveries into pharmacological strategies to target cytoskeletal function during aging.