Stress responses of PML nuclear domains are ablated by ataxin-1 and other nucleoprotein inclusions.
The polyglutamine diseases are characterized by expansion of triplet CAG repeats that encode polyglutamine tracts in otherwise unrelated proteins. One plausible explanation for the neurodegeneration of these disorders proposes that inclusions of such proteins sequester other significant nuclear proteins in inactive form. The present study shows that PML protein is sequestered by inclusions of the pathogenic mutant form of the polyglutamine protein ataxin-1 and that this sequestration removes from the nucleus the free 0.2-1 microm diameter PML nuclear domains (PML-NDs), together with at least one of their many cargo proteins (Sp100). The present study demonstrates that this sequestration can be effected equally by another nuclear protein, RED, which lacks a polyglutamine tract, but expresses a polar zipper repeat. The sequestered PML-NDs no longer respond to stress signals (heat shock or ionizing radiation) to which they are normally sensitive. In both cases, there is independent evidence that the cells initiate other responses to their injury (nuclear translocation of heat shock protein or generation of gamma-H2AX-rich nuclear foci, respectively). The data thus provide strong evidence that multiple species of nuclear inclusion functionally sequester PML-NDs. This mechanism is likely to distort cellular responses to injury of many different types.
Dovey
Claire L
CL
Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
Varadaraj
Archana
A
Wyllie
Andrew H
AH
Rich
Tina
T
D000067696:Ataxin-1; D000067528:Ataxins; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism* / Q000528:radiation effects; D004249:DNA Damage; D005720:Gamma Rays; D006360:Heat-Shock Proteins / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D045586:Intranuclear Inclusion Bodies / Q000502:physiology* / Q000528:radiation effects; D009363:Neoplasm Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009687:Nuclear Proteins / Q000378:metabolism* / Q000502:physiology*; D009698:Nucleoproteins / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
C000593749:ATXN1 protein, human; D000067696:Ataxin-1; D000067528:Ataxins; D006360:Heat-Shock Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D009698:Nucleoproteins; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human