Alteration of POLDIP3 Splicing Associated With Loss of Function of TDP-43 in Tissues Affected With ALS

PLoS One. 2012;7(8):e43120. doi: 10.1371/journal.pone.0043120. Epub 2012 Aug 10.

Abstract

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease caused by selective loss of motor neurons. In the ALS motor neurons, TAR DNA-binding protein of 43 kDa (TDP-43) is dislocated from the nucleus to cytoplasm and forms inclusions, suggesting that loss of a nuclear function of TDP-43 may underlie the pathogenesis of ALS. TDP-43 functions in RNA metabolism include regulation of transcription, mRNA stability, and alternative splicing of pre-mRNA. However, a function of TDP-43 in tissue affected with ALS has not been elucidated. We sought to identify the molecular indicators reflecting on a TDP-43 function. Using exon array analysis, we observed a remarkable alteration of splicing in the polymerase delta interacting protein 3 (POLDIP3) as a result of the depletion of TDP-43 expression in two types of cultured cells. In the cells treated with TDP-43 siRNA, wild-type POLDIP3 (variant-1) decreased and POLDIP3 lacking exon 3 (variant-2) increased. The RNA binding ability of TDP-43 was necessary for inclusion of POLDIP3 exon 3. Moreover, we found an increment of POLDIP3 variant-2 mRNA in motor cortex, spinal cord and spinal motor neurons collected by laser capture microdissection with ALS. Our results suggest a loss of TDP-43 function in tissues affected with ALS, supporting the hypothesis that a loss of function of TDP-43 underlies the pathogenesis of ALS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing*
  • Amyotrophic Lateral Sclerosis / genetics*
  • Amyotrophic Lateral Sclerosis / metabolism*
  • Cell Line
  • Cell Size
  • Cells, Cultured
  • DNA-Binding Proteins / metabolism*
  • Exons
  • Gene Expression
  • HeLa Cells
  • Humans
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Protein Interaction Domains and Motifs
  • Protein Isoforms
  • RNA Precursors / genetics
  • RNA Precursors / metabolism
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / metabolism

Substances

  • DNA-Binding Proteins
  • Nuclear Proteins
  • POLDIP3 protein, human
  • Protein Isoforms
  • RNA Precursors
  • RNA-Binding Proteins

Grant support

This work was supported by Grant-1 in-Aid for Scientific Research (A) (23240049, 22249036) and Grant-in-Aid for challenging Exploratory Research (22659169) from Japan Society for the Promotion of Science, and Grant-in-Aid for Scientific Research on Innovative Areas (22113506) from Ministry of Education, Culture, Sports, Sceience and Technology, Japan, and Grant-in-Aid for the Research Committee of CNS Degenerative Diseases (201024015A) form Ministry of Health, Labor and Welfare, Japan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.