Regulatory Functions of TDP-43 and FMRP in Non-Neuronal Diseases: Are Co-Targeted mRNAs the Keys?

RNA binding proteins (RBPs) act as the central nodal point in shaping the cellular transcriptome through their involvement in various aspects of RNA metabolism including stability, splicing, polyadenylation, modifications, translation and transport. Dysregulation in the function of various RBPs can be associated with different human pathophysiological conditions. Owing to their ability to regulate various RNA metabolism-associated processes, the same RBPs can functionally be involved in human pathologies with distinct underlying pathophysiological mechanisms. Two such important RBPs, namely TDP-43 and FMRP, have long been implicated respectively, in neurodegenerative diseases like amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) etc. and in neurodevelopmental diseases like fragile-X syndrome (FXS). However, numerous recent reports indicate that these ubiquitously expressed proteins can regulate important cellular functions and signaling cascades, misregulation which results in different disease phenotypes. In this review, the association of TDP-43 and FMRP with different non-neuronal disease mechanisms has been discussed. Furthermore, to anticipate yet-to-be-explored non-neuronal disease mechanisms involving mismanagement in co-regulation of spatial and temporal transport/translation processes of TDP-43 and FMRP targeted RNAs, as observed in neuronal diseases for example, autism, RNA target databases of these two proteins are compared followed by GO and KEGG analysis. The lists of RNAs co-targeted by TDP-43 and FMRP are presumably involved in different non-neuronal diseases and disease-associated mechanistic pathways and will open up new phases of research to establish new disease mechanism(s). Different disease mechanisms and their interconnections expectantly will also lead to the discovery of new drug targets.