title: Expression and p75 neurotrophin receptor dependence of cholesterol synthetic enzymes in adult mouse brain.
abstract: Normal brain function depends critically on cholesterol. Although cholesterol is synthesized locally in the adult brain, the precise anatomical localization of cholesterogenic enzymes is not known. Here we show that 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoAred) and 7-dehydrocholesterol reductase (7dhcred), the first and last enzymes, respectively, in the cholesterol biosynthesis pathway, are co-expressed in neurons throughout adult murine brain. Co-localization is most prominent in cortical, hippocampal, and cholinergic neurons. Since adult hippocampal and cholinergic neurons express p75 neurotrophin receptors (p75NTR) we hypothesized that p75NTR regulates expression of cholesterogenic enzymes. Treatment of Neuro2a neuroblastoma cells or primary cerebellar cultures with siRNA downregulates p75NTR and decreases the expression level of HMG-CoAred and 7dhcred. Native neuroblastoma cell lines with differential expression of p75NTR differentially express 7dhcred; 7dhcred expression correlates with p75NTR expression. This suggests that, in p75NTR-expressing cells, p75NTR regulates cholesterol synthesis through regulation of HMG-CoAred and 7dhcred expression. The unexpected localization of cholesterogenic enzymes in adult neurons suggests that at least some adult neurons retain the ability to synthesize cholesterol.
authors.affiliation: Pediatric Center for Neuroscience, Children's Hospital of Pittsburgh, Department of Pediatrics, University of Pittsburgh, PA, United States.
authors.forename: Zeljka
authors.initials: Z
authors.lastname: Korade
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Mi
authors.forename: Carmel
authors.initials: C
authors.lastname: Portugal
authors.forename: Nina F
authors.initials: NF
authors.lastname: Schor
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000096:biosynthesis*; D015536:Down-Regulation / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000201:enzymology*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D020800:Receptor, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D020800:Receptor, Nerve Growth Factor; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019995:7-dehydrocholesterol reductase; D000109:Acetylcholine