Paralogous lncRNAs CYTOR and MORRBID share a conserved trans-acting function in MEK–ERK signalling, preprint reports

A preprint deposited on bioRxiv examines CYTOR and MORRBID, two paralogous long non-coding RNAs (lncRNAs) — RNA molecules that do not encode protein but play regulatory roles in gene expression. MORRBID is evolutionarily conserved across vertebrates, while CYTOR is its primate-specific duplicate; both arose from genomic duplication.

LncRNAs are known for rapid evolutionary turnover and functional divergence, making the question of what happens to regulatory function after duplication scientifically interesting. The authors demonstrate that, despite acquiring distinct transcript variants shaped by their different genomic neighbourhoods, CYTOR and MORRBID maintain a robust, shared trans-acting function — meaning they act on genes located elsewhere in the genome rather than purely in cis. Specifically, both lncRNAs influence MEK–ERK signalling, a pathway central to cell proliferation, differentiation, and survival.

The finding suggests that functional conservation can persist across lncRNA paralogues even when sequence and structural context have substantially diverged — a result with implications for understanding how non-coding regulatory elements evolve and how duplication shapes genome function. This is a preprint and has not yet been peer-reviewed.