The lncRNA011760/miR-Novel-91/NIPA2 ceRNA Network Regulates Salinity Stress Response in Sea Cucumber (Apostichopus japonicus)

Low-salinity stress poses a critical constraint on commercial aquaculture and the survival of the sea cucumber (Apostichopus japonicus). This study investigated the regulatory network involving lncRNA011760, miR-novel-91, and their target gene NIPA2 in response to salinity fluctuations. Using integrated in vivo and in vitro functional assays, we demonstrate that lncRNA011760 acts as a competitive endogenous RNA (ceRNA) to sponge miR-novel-91, thereby alleviating the post-transcriptional repression of NIPA2. Based on these molecular dynamics, we propose a novel inhibition-adaptation-survival three-stage model. Initially (0–3 h), acute NIPA2 upregulation enhances Mg2+ transport efficiency to mitigate osmotic shock. During the mid-stage (3–24 h), miR-novel-91-mediated NIPA2 suppression creates a transient biosynthetic window, facilitating a shift from passive tolerance to active metabolic adaptation. Ultimately (24–48 h), lncRNA-driven NIPA2 restoration sustains Mg2+ homeostasis, allowing the organism to enter a low-metabolism survival mode. These stage-specific shifts reflect the inherent physiological strategies of sea cucumbers as osmoconformers.