Jiajia Han | Search PubMed

PubMed2026

Skin-innervating glutamatergic neurons modulate aging.

Peripheral nerves regulate skin homeostasis by secreting neurotransmitters, but their role during skin aging remains incompletely understood. Here, we report that cutaneous denervation accelerates skin aging, as evidenced by collagen reduction. Neurofilament heavy chain (Nefh) is decreased in aged skin and is predominantly expressed in vesicular glutamate transporter 2-positive (Vglut2+) skin-innervating glutamatergic neurons. Notably, dermal fibroblasts, the primary producers of collagen, frequently contact Nefh+ nerve fibers. Moreover, Nefh deletion in Vglut2+ glutamatergic neurons drives skin fibroblast senescence and collagen loss, whereas additional glutamate improves skin aging phenotypes. Mechanistically, cyclin-dependent kinase 5 (Cdk5) interacts with both Nefh and Vglut2 and maintains glutamate release and collagen homeostasis. Additionally, in skin fibroblasts, solute carrier family 1 member 3 (Slc1a3) governs the collagen-promoting and anti-senescence functions of glutamate. Together, these findings reveal Nefh-mediated glutamatergic neuromodulation of skin aging and provide therapeutic targets for aging-related skin disorders.

Animals↗

PubMed2026

Twisting the End Game: How Telomere Chromatin Modifications Shape Telomere Maintenance.

Cell division inevitably shortens telomeric DNA owing to the end-replication problem. Eukaryotic chromosomes possess specialized telomere structures to maintain genomic stability. In most proliferative cells, telomerase adds telomeric repeats during S-phase. In differentiated cells where telomerase is silenced, telomeres shorten progressively, thereby compromising genomic integrity. Consequently, cancer cells universally activate alternative telomere maintenance mechanisms during malignant transformation: ~80% reactivate telomerase, while a portion of the rest rely on BIR (break-induced replication)-mediated homologous recombination-based ALT (alternative lengthening of telomeres). Although these mechanisms are stable once established, the initial determinants influencing a cancer cell's choice remain poorly understood. This review discusses recent molecular insights into how telomeric chromatin properties profoundly impact this choice. After briefly introducing telomere chromatin characteristics and key players in its maintenance and dynamics, we discuss the mechanisms by which cancer cells acquire distinct telomere replication capabilities. In particular, we present an in-depth analysis linking telomere heterochromatin status to ALT. Furthermore, based on recent advances, we propose a coupled feedforward loop model explaining how the ALT state becomes "locked in" once initiated. Finally, we offer novel perspectives on rational, telomere-centric therapeutic interventions for ALT-positive cancers, focusing on strategies designed to disrupt such feedforward loops by manipulating telomeric chromatin structure.

Humans↗