Study identifies SID-1-dependent genes affecting reproduction and transgenerational epigenetic inheritance in C. elegans
Researchers studying the nematode C. elegans have identified two SID-1-dependent genes, sdg-1 and sdg-2, whose altered expression can reduce brood size and affect germline development across generations. Loss of the transmembrane protein SID-1 — which normally allows double-stranded RNA to enter cells — triggers gene expression changes that can persist for hundreds of generations. The findings suggest that extracellular RNA import may have evolved as a mechanism to modulate long-lasting epigenetic states, with potential implications for understanding transgenerational inheritance.
A new preprint study on the roundworm C. elegans reports the identification of an expanded set of SID-1-dependent genes (SDGs) — genes whose expression is altered when the dsRNA-importing protein SID-1 is absent — and characterizes two of them, sdg-1 and sdg-2, in detail. Both genes are expressed in the germline, and deletion of either can reduce brood size in certain lineages, indicating reproductive consequences. The SDG-1 protein shows dynamic localization, appearing in nuclei under some conditions and colocalizing with perinuclear germ granules and microtubules, while SDG-2 is constitutively present in both cytoplasm and nucleus. Notably, animals engineered to express an SDG-1::mCherry fusion protein show germline morphology defects and fewer early progeny, and some of these defects persist even in siblings where the sdg-1 coding sequence has been deleted, pointing to transgenerational epigenetic effects of the tagged protein itself. SDG-2's predicted structure suggests it may interact with TRA-1, a Gli-type transcription factor that regulates spermatogenesis, hinting at a mechanistic link to sex-specific reproductive pathways. The authors propose that SID-1-mediated import of extracellular dsRNA — or other SID-1 functions — may have evolved to help organisms manage the lingering effects of ancestral epigenetic changes on reproduction.
What's missing
As a preprint, this work has not yet undergone formal peer review. The study does not establish whether analogous SID-1-dependent transgenerational mechanisms exist in organisms beyond C. elegans, nor does it resolve the precise molecular pathway by which SID-1 activity regulates SDG expression. The functional significance of SDG-2's predicted interaction with TRA-1 remains unvalidated experimentally.
What different sources said
- bioRxivCenter
Two SID-1-dependent genes sensitive to heritable epigenetic changes can also impact reproduction
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