Differential contributions of Caenorhabditis elegans histone deacetylases to huntingtin polyglutamine toxicity.
Expansion of a polyglutamine tract in the huntingtin protein causes neuronal degeneration and death in Huntington's disease patients, but the molecular mechanisms underlying polyglutamine-mediated cell death remain unclear. Previous studies suggest that expanded polyglutamine tracts alter transcription by sequestering glutamine rich transcriptional regulatory proteins, thereby perturbing their function. We tested this hypothesis in Caenorhabditis elegans neurons expressing a human huntingtin fragment with an expanded polyglutamine tract (Htn-Q150). Loss of function alleles and RNA interference (RNAi) were used to examine contributions of C. elegans cAMP response element-binding protein (CREB), CREB binding protein (CBP), and histone deacetylases (HDACs) to polyglutamine-induced neurodegeneration. Deletion of CREB (crh-1) or loss of one copy of CBP (cbp-1) enhanced polyglutamine toxicity in C. elegans neurons. Loss of function alleles and RNAi were then used to systematically reduce function of each C. elegans HDAC. Generally, knockdown of individual C. elegans HDACs enhanced Htn-Q150 toxicity, but knockdown of C. elegans hda-3 suppressed toxicity. Neuronal expression of hda-3 restored Htn-Q150 toxicity and suggested that C. elegans HDAC3 (HDA-3) acts within neurons to promote degeneration in response to Htn-Q150. Genetic epistasis experiments suggested that HDA-3 and CRH-1 (C. elegans CREB homolog) directly oppose each other in regulating transcription of genes involved in polyglutamine toxicity. hda-3 loss of function failed to suppress increased neurodegeneration in hda-1/+;Htn-Q150 animals, indicating that HDA-1 and HDA-3 have different targets with opposing effects on polyglutamine toxicity. Our results suggest that polyglutamine expansions perturb transcription of CREB/CBP targets and that specific targeting of HDACs will be useful in reducing associated neurodegeneration.
Bates
Emily A
EA
Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Victor
Martin
M
Jones
Adriana K
AK
Shi
Yang
Y
Hart
Anne C
AC
D000375:Aging / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D050882:CREB-Binding Protein / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D002232:Carbocyanines; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology; D006655:Histone Deacetylases / Q000145:classification / Q000502:physiology*; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006877:Hydroxamic Acids / Q000494:pharmacology; D009410:Nerve Degeneration / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism / Q000633:toxicity*; D034622:RNA Interference / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
C035005:3,3'-dihexadecylindocarbocyanine; D002232:Carbocyanines; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; C086055:HTT protein, human; D000071058:Huntingtin Protein; D006877:Hydroxamic Acids; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D012333:RNA, Messenger; C097188:polyglutamine; C012589:trichostatin A; D050882:CREB-Binding Protein; D006655:Histone Deacetylases