TPM1 drives cytoskeleton-immunometabolism coupling and LGALS9/CD45-mediated neuroinflammatory propagation in retinitis pigmentosa.

Abstract

Retinitis pigmentosa (RP), the most prevalent inherited retinal degeneration, features progressive photoreceptor loss with no approved disease-modifying therapies. While microglia-driven neuroinflammation accelerates RP progression, its sustaining mechanisms remain elusive. Through integrated multiomics profiling of retinal degeneration 10 (rd10) mice, we identify tropomyosin 1 (TPM1) as a previously unrecognized cytoskeletal-immune regulator orchestrating spatial neuroinflammation in RP. Genetic ablation of <i>Tpm1</i> attenuated microglial reactivity and preserved vision, whereas overexpression triggered self-reinforcing inflammation via four interlocked axes: (i) TPM1-mediated activator protein-1 (AP-1) hyperactivation initiates senescence-associated secretory phenotype (SASP) through mitogen-activated protein kinase (MAPK) kinase/extracellular signal-regulated kinase 3-dependent MAPK signaling; (ii) SASP subsequently mediates reduced phagocytosis; (iii) <i>Tpm1-Apoe/Fabp5</i> axis disruption precipitates lipid droplet accumulation with cholesterol crystallization; (iv) galectin-9 (LGALS9)/CD45-mediated intermicroglial signaling propagates inflammatory signals across the retina. Our work redefines TPM1 as a linchpin in self-sustaining neurodegeneration cycles, where cytoskeletal dysfunction fuels immunometabolic collapse. These findings unveil precision therapeutic strategies targeting TPM1 hubs-notably the LGALS9/CD45 axis-to disrupt inflammatory cycles while preserving retinal homeostasis.