Dysfunction of the cholesterol biosynthetic pathway in Huntington's disease.
The expansion of a polyglutamine tract in the ubiquitously expressed huntingtin protein causes Huntington's disease (HD), a dominantly inherited neurodegenerative disease. We show that the activity of the cholesterol biosynthetic pathway is altered in HD. In particular, the transcription of key genes of the cholesterol biosynthetic pathway is severely affected in vivo in brain tissue from HD mice and in human postmortem striatal and cortical tissue; this molecular dysfunction is biologically relevant because cholesterol biosynthesis is reduced in cultured human HD cells, and total cholesterol mass is significantly decreased in the CNS of HD mice and in brain-derived ST14A cells in which the expression of mutant huntingtin has been turned on. The transcription of the genes of the cholesterol biosynthetic pathway is regulated via the activity of sterol regulatory element-binding proteins (SREBPs), and we found an approximately 50% reduction in the amount of the active nuclear form of SREBP in HD cells and mouse brain tissue. As a consequence, mutant huntingtin reduces the transactivation of an SRE-luciferase construct even under conditions of SREBP overexpression or in the presence of an exogenous N-terminal active form of SREBP. Finally, the addition of exogenous cholesterol to striatal neurons expressing mutant huntingtin prevents their death in a dose-dependent manner. We conclude that the cholesterol biosynthetic pathway is impaired in HD cells, mice, and human subjects, and that the search for HD therapies should also consider cholesterol levels as both a potential target and disease biomarker.
Valenza
Marta
M
Department of Pharmacological Sciences, Center of Excellence on Neurodegenerative Diseases, University of Milan, 20133 Milan, Italy.
Rigamonti
Dorotea
D
Goffredo
Donato
D
Zuccato
Chiara
C
Fenu
Simone
S
Jamot
Laure
L
Strand
Andrew
A
Tarditi
Alessia
A
Woodman
Ben
B
Racchi
Marco
M
Mariotti
Caterina
C
Di Donato
Stefano
S
Corsini
Alberto
A
Bates
Gillian
G
Pruss
Rebecca
R
Olson
James M
JM
Sipione
Simonetta
S
Tartari
Marzia
M
Cattaneo
Elena
E
D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002784:Cholesterol / Q000096:biosynthesis*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006816:Huntington Disease / Q000378:metabolism* / Q000473:pathology*; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D051780:Sterol Regulatory Element Binding Protein 1 / Q000378:metabolism; D013997:Time Factors; D014162:Transfection / Q000379:methods
D012333:RNA, Messenger; D051780:Sterol Regulatory Element Binding Protein 1; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019995:7-dehydrocholesterol reductase