Latent process genes for cell differentiation are common decoders of neurite extension length

Abstract

A latent process involving signal transduction and gene expression is needed as a preparation step for cellular function. We previously found that nerve growth factor (NGF)-induced cell differentiation has a latent process, which is dependent on ERK activity and gene expression and required for subsequent neurite extension. A latent process can be considered a preparation step that decodes extracellular stimulus information into cellular functions; however, molecular mechanisms of this process remain unknown. I identified Metrnl, Dclk1, and Serpinb1a as latent process (LP) genes that are induced during the latent process with distinct temporal expression profiles and are required for subsequent neurite extension in PC12 cells. The LP gene products showed distinct spatial localization. Overexpression of all LP genes together, but not of each gene separately, enhanced NGF-induced neurite extension. The LP genes showed distinct dependency on the duration of ERK activity, and they were also induced during the latent process of pituitary adenylate cyclase-activating polypeptide (PACAP)- and forskolin-induced cell differentiation. Regardless of neurotrophic factors, expression levels of the LP genes during the latent process (0-12 h), but not phosphorylation levels of ERK, always correlated with subsequent neurite extension length (12-24 h). Thus, the LP genes appeared to be the common decoders for neurite extension length regardless of neurotrophic factors, and they may function in distinct temporal and spatial manners during the latent process. Our findings provide molecular insight into the physiological meaning of the latent process as the preparation step for decoding information for future phenotypic change.