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LON-8 is a small secreted hypodermal precursor protein (signal
peptide-bearing) that acts on the cuticle/apical extracellular matrix
(aECM) to regulate larval elongation/body size and male ray morphology,
acting largely independently of DBL-1/Sma/Mab transcriptional control but
genetically interacting with the collagen-modifying enzymes dpy-11 and
dpy-18.
"lon-8/Y59A8B.20 encodes a small secreted hypodermal protein that functions in the extracellular cuticle/aECM to regulate larval elongation/body size and male ray morphology, acting largely independently of DBL-1/Sma/Mab transcriptional control but genetically interacting with collagen-modifying enzymes dpy-11 and dpy-18."
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The strongest mechanistic interpretation is that LON-8 is a secreted
hypodermal factor acting on the cuticle/aECM, influencing body length and
specialized cuticular structures such as male rays; the biochemical mode
of action remains undefined and any BPTI/Kunitz protease-inhibitor
activity is treated as a hypothesis only.
"The strongest interpretation supported by experimental genetics is that LON-8 is a **secreted hypodermal factor acting on the cuticle/aECM**, influencing body length and specialized cuticular structures (male rays). This is supported by its signal peptide, hypodermal expression, and genetic suppression by collagen-modifying enzyme knockdowns (dpy-11, dpy-18)."
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A 2025 systematic endogenous-tagging study (Ragle et al., bioRxiv) created
an endogenous LON-8::mNG knock-in, describing LON-8 as a secreted protein
implicated in cuticle morphology, and reported localization to cuticle
structures including the male tail fan, with atypical FRAP recovery in the
L4 vulva relative to most knock-ins.
"report systematic endogenous tagging of aECM components including **LON-8::mNG**, describing LON-8 as a secreted protein implicated in cuticle morphology. They further report localization to cuticle structures including the **male tail fan**, and note atypical FRAP recovery for LON-8::mNG in the L4 vulva relative to most knock-ins."
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A C. elegans apical extracellular matrix review (Cohen & Sundaram, 2020)
lists LON-8 among proteins important for building male rays, describing it
as a short, secreted peptide/protein in the ray/cuticle context.
"Review on *C. elegans* apical extracellular matrices lists **LON-8** among proteins important for building **male rays**, describing it as a **short, secreted peptide/protein** in the ray/cuticle context"