ALS-associated mutations in TDP-43 increase its stability and promote TDP-43 complexes with FUS/TLS.
Dominant mutations in two functionally related DNA/RNA-binding proteins, trans-activating response region (TAR) DNA-binding protein with a molecular mass of 43 KDa (TDP-43) and fused in sarcoma/translocation in liposarcoma (FUS/TLS), cause an inherited form of ALS that is accompanied by nuclear and cytoplasmic aggregates containing TDP-43 or FUS/TLS. Using isogenic cell lines expressing wild-type or ALS-linked TDP-43 mutants and fibroblasts from a human patient, pulse-chase radiolabeling of newly synthesized proteins is used to determine, surprisingly, that ALS-linked TDP-43 mutant polypeptides are more stable than wild-type TDP-43. Tandem-affinity purification and quantitative mass spectrometry are used to identify TDP-43 complexes not only with heterogeneous nuclear ribonucleoproteins family proteins, as expected, but also with components of Drosha microprocessor complexes, consistent with roles for TDP-43 in both mRNA processing and microRNA biogenesis. A fraction of TDP-43 is shown to be complexed with FUS/TLS, an interaction substantially enhanced by TDP-43 mutants. Taken together, abnormal stability of mutant TDP-43 and its enhanced binding to normal FUS/TLS imply a convergence of pathogenic pathways from mutant TDP-43 and FUS/TLS in ALS.
Ling
Shuo-Chien
SC
Ludwig Institute for Cancer Research and Department of Neuroscience, University of California at San Diego, La Jolla, CA 92093-0670, USA.
Albuquerque
Claudio P
CP
Han
Joo Seok
JS
Lagier-Tourenne
Clotilde
C
Tokunaga
Seiya
S
Zhou
Huilin
H
Cleveland
Don W
DW
D000595:Amino Acid Sequence; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics*; D001665:Binding Sites; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D055550:Protein Stability; D034702:RNA-Binding Protein FUS / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D004268:DNA-Binding Proteins; D034702:RNA-Binding Protein FUS; D049452:Green Fluorescent Proteins