A mantle-enriched lncRNA7379 potentially modulates Smad1/5 signaling during shell formation in Pinctada fucata martensii.

Long non-coding RNAs (lncRNAs) are emerging regulators of diverse biological processes, but their mechanistic roles in molluscan biomineralization remain incompletely understood. Here, we identified a novel 635-nt lncRNA, lncRNA7379, from mantle transcriptome data of the pearl oyster Pinctada fucata martensii. lncRNA7379 showed a mantle-enriched expression pattern and dynamic responses after shell notching and under elevated temperature. Because shell injury and thermal exposure elicit broad physiological responses, these expression changes were treated as complementary contextual evidence rather than as biomineralization-specific readouts. RNA interference-mediated depletion of lncRNA7379 altered shell ultrastructure and increased the transcript abundance of MSX and Smad1/5. Subcellular fractionation and RNA FISH showed that lncRNA7379 was predominantly cytoplasmic. In heterologous 293 T cells, lncRNA7379 overexpression reduced Smad1/5 mRNA and protein levels, while RNA immunoprecipitation assays showed enrichment of lncRNA7379 in Smad1/5 immunoprecipitates. Together, these data support an association of lncRNA7379 with shell formation and suggest that it may modulate the PfSmad1/5-related regulatory network.