Neurodegeneration-associated TDP-43 Interacts with Fragile X Mental Retardation Protein (FMRP)/Staufen (STAU1) and

Despite the identification of the 43 kDa transactive response DNA-binding protein (TDP-43) as a major pathological signatory protein in a wide range of neurodegenerative diseases, the mechanistic role of TDP-43 in neurodegenerative disorders is still poorly understood. Here, we report that TDP-43 is physically associated with fragile X mental retardation protein (FMRP) and Staufen (STAU1) to form a functional complex. Differential microarray analysis revealed that the expression of a collection of functionally important genes including Sirtuin (SIRT1) is regulated by this complex. RNA-immunoprecipitation (RIP) and RNA pull-down assays demonstrated that TDP43/FMRP/STAU1 specifically binds to the 3� -UTR of SIRT1 mRNA, and that knockdown the expression of any one of these three proteins resulted in the reduction of SIRT1 mRNA and protein. SIRT1 is implicated in double-stranded DNA break repair and is required for cell survival. Indeed, depletion of TDP-43/FMRP/STAU1 sensitizes cells to apoptosis and DNA damages. Collectively, our results revealed a molecular mechanism for the cellular function of TDP-43 and might shed new light on the understanding of the mechanistic role of TDP-43 in neurodegenerative diseases.