Cholesterol 24-hydroxylase is an enzyme that in humans is encoded by the CYP46A1gene.[1][2]
This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This endoplasmic reticulum protein is expressed in the brain, where it converts cholesterol to 24S-hydroxycholesterol. While cholesterol cannot pass the blood–brain barrier, 24S-hydroxycholesterol can be secreted in the brain into the circulation to be returned to the liver for catabolism.[2]
Björkhem I, Lütjohann D, Diczfalusy U, et al. (1998). "Cholesterol homeostasis in human brain: turnover of 24S-hydroxycholesterol and evidence for a cerebral origin of most of this oxysterol in the circulation". J. Lipid Res. 39 (8): 1594–600. PMID9717719.
Bogdanovic N, Bretillon L, Lund EG, et al. (2002). "On the turnover of brain cholesterol in patients with Alzheimer's disease. Abnormal induction of the cholesterol-catabolic enzyme CYP46 in glial cells". Neurosci. Lett. 314 (1–2): 45–8. doi:10.1016/S0304-3940(01)02277-7. PMID11698143.
Papassotiropoulos A, Streffer JR, Tsolaki M, et al. (2003). "Increased brain beta-amyloid load, phosphorylated tau, and risk of Alzheimer disease associated with an intronic CYP46 polymorphism". Arch. Neurol. 60 (1): 29–35. doi:10.1001/archneur.60.1.29. PMID12533085.
Mast N, Norcross R, Andersson U, et al. (2004). "Broad substrate specificity of human cytochrome P450 46A1 which initiates cholesterol degradation in the brain". Biochemistry. 42 (48): 14284–92. doi:10.1021/bi035512f. PMID14640697.
Ota T, Suzuki Y, Nishikawa T, et al. (2004). "Complete sequencing and characterization of 21,243 full-length human cDNAs". Nat. Genet. 36 (1): 40–5. doi:10.1038/ng1285. PMID14702039.
Chalmers KA, Culpan D, Kehoe PG, et al. (2004). "APOE promoter, ACE1 and CYP46 polymorphisms and beta-amyloid in Alzheimer's disease". NeuroReport. 15 (1): 95–8. doi:10.1097/00001756-200401190-00019. PMID15106838.
Borroni B, Archetti S, Agosti C, et al. (2004). "Intronic CYP46 polymorphism along with ApoE genotype in sporadic Alzheimer Disease: from risk factors to disease modulators". Neurobiol. Aging. 25 (6): 747–51. doi:10.1016/j.neurobiolaging.2003.08.004. PMID15165699.
Kabbara A, Payet N, Cottel D, et al. (2004). "Exclusion of CYP46 and APOM as candidate genes for Alzheimer's disease in a French population". Neurosci. Lett. 363 (2): 139–43. doi:10.1016/j.neulet.2004.03.066. PMID15172102.
Wang B, Zhang C, Zheng W, et al. (2004). "Association between a T/C polymorphism in intron 2 of cholesterol 24S-hydroxylase gene and Alzheimer's disease in Chinese". Neurosci. Lett. 369 (2): 104–7. doi:10.1016/j.neulet.2004.07.020. PMID15450677.
Golanska E, Hulas-Bigoszewska K, Wojcik I, et al. (2005). "CYP46: a risk factor for Alzheimer's disease or a coincidence?". Neurosci. Lett. 383 (1–2): 105–8. doi:10.1016/j.neulet.2005.03.049. PMID15936520.
Shibata N, Kawarai T, Lee JH, et al. (2006). "Association studies of cholesterol metabolism genes (CH25H, ABCA1 and CH24H) in Alzheimer's disease". Neurosci. Lett. 391 (3): 142–6. doi:10.1016/j.neulet.2005.08.048. PMID16157450.
Ma SL, Tang NL, Lam LC, Chiu HF (2006). "Polymorphisms of the cholesterol 24-hydroxylase (CYP46A1) gene and the risk of Alzheimer's disease in a Chinese population". International psychogeriatrics / IPA. 18 (1): 37–45. doi:10.1017/S1041610205003108. PMID16734927.
Wang F, Jia J (2007). "Polymorphisms of cholesterol metabolism genes CYP46 and ABCA1 and the risk of sporadic Alzheimer's disease in Chinese". Brain Res. 1147: 34–8. doi:10.1016/j.brainres.2007.02.005. PMID17335784.