24S-Hydroxycholesterol

24S-Hydroxycholesterol (24S-HC), also known as cholest-5-ene-3,24-diol or cerebrosterol, is an endogenous oxysterol produced by neurons in the brain to maintain cholesterol homeostasis.[1] It was discovered in 1953 by Alberto Ercoli, S. Di Frisco, and Pietro de Ruggieri, who first isolated the molecule in the horse brain[2] and then demonstrated its presence in the human brain.[3]

24S-Hydroxycholesterol
Names
IUPAC name
cholest-5-ene-3,24-diol
Other names
cerebrosterol
Identifiers
3D model (JSmol)
3218472
ChEBI
ChEMBL
ChemSpider
KEGG
UNII
Properties
C27H46O2
Molar mass 402.653 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Structure

24S-HC is produced by a hydroxy group substitution at carbon number 24 in cholesterol, catalyzed by the enzyme cholesterol 24-hydroxylase (CYP46A1).[4]

Production of 24S-hydroxycholesterol from cholesterol, as catalyzed by CYP46A1.

Function

24S-HC binds to apolipoproteins such as apoE, apoJ, and apoA1 to form HDL-like complexes[5] which can cross the blood-brain barrier more easily than free cholesterol. Thus, 24S-HC production serves as one of several counterbalancing mechanisms for cholesterol synthesis in the brain.[1][6] After entering general blood circulation and traveling to the liver, 24S-HC can be sulfated, glucuronidated, or converted into bile acids, which can ultimately be excreted.[7]

24S-HC is an agonist of liver X receptors, a class of nuclear receptors that sense oxysterols. In the brain, liver X receptor beta is the primary LXR type which interacts with 24S-HC.[5] 24S-HC levels sensed by LXRs can regulate the expression of SREBP mRNA and protein, which in turn regulate cholesterol synthesis and fatty acid synthesis.[8]

24S-HC may participate in several aspects of brain development and function, such as axon and dendrite growth or synaptogenesis.[4] Regulation of 24S-HC metabolism in neurons may play a role in their health and function, as well as their response to injury or disease.[9] Blood plasma levels of 24S-HC may be altered after acute brain injuries such as stroke[10] or in neurodegenerative diseases such as Alzheimer's disease, Huntington's disease, and multiple sclerosis.[11][12]

References
  1. Mahley RW (2016). "Central Nervous System Lipoproteins: ApoE and Regulation of Cholesterol Metabolism". Arterioscler Thromb Vasc Biol. 36 (7): 1305–15. doi:10.1161/ATVBAHA.116.307023. PMC 4942259. PMID 27174096.
  2. Ercoli A, Di Frisco S, De Ruggieri P (1953). "Isolation, constitution and biological significance of cerebrosterol, a companion of cholesterol in the horse brain". Boll Soc Ital Biol Sper. 29 (4): 494–7. PMID 13105923.
  3. Di Frisco S, De Ruggieri P, Ercoli A (1953). "Isolation of cerebrosterol from human brain". Boll Soc Ital Biol Sper. 29 (7): 1351–2. PMID 13140512.
  4. Lund EG, Xie C, Kotti T, Turley SD, Dietschy JM, Russell DW (2003). "Knockout of the cholesterol 24-hydroxylase gene in mice reveals a brain-specific mechanism of cholesterol turnover". J Biol Chem. 278 (25): 22980–8. doi:10.1074/jbc.M303415200. PMID 12686551.
  5. Wang Y, Kumar N, Crumbley C, Griffin PR, Burris TP (2010). "A second class of nuclear receptors for oxysterols: Regulation of RORalpha and RORgamma activity by 24S-hydroxycholesterol (cerebrosterol)". Biochim Biophys Acta. 1801 (8): 917–23. doi:10.1016/j.bbalip.2010.02.012. PMC 2886165. PMID 20211758.
  6. Björkhem I (2007). "Rediscovery of cerebrosterol". Lipids. 42 (1): 5–14. doi:10.1007/s11745-006-1003-2. PMID 17393206.
  7. Lütjohann D (2006). "Cholesterol metabolism in the brain: importance of 24S-hydroxylation". Acta Neurol Scand Suppl. 185: 33–42. doi:10.1111/j.1600-0404.2006.00683.x. PMID 16866909.
  8. Cartagena CM, Burns MP, Rebeck GW (2010). "24S-hydroxycholesterol effects on lipid metabolism genes are modeled in traumatic brain injury". Brain Res. 1319: 1–12. doi:10.1016/j.brainres.2009.12.080. PMC 2826556. PMID 20053345.
  9. Sun MY, Linsenbardt AJ, Emnett CM, Eisenman LN, Izumi Y, Zorumski CF, Mennerick S (2016). "24(S)-Hydroxycholesterol as a Modulator of Neuronal Signaling and Survival". Neuroscientist. 22 (2): 132–44. doi:10.1177/1073858414568122. PMC 4821654. PMID 25628343.
  10. Sun MY, Taylor A, Zorumski CF, Mennerick S (2017). "24S-hydroxycholesterol and 25-hydroxycholesterol differentially impact hippocampal neuronal survival following oxygen-glucose deprivation". PLOS ONE. 12 (3): e0174416. Bibcode:2017PLoSO..1274416S. doi:10.1371/journal.pone.0174416. PMC 5367825. PMID 28346482.
  11. Leoni V, Caccia C (2013). "24S-hydroxycholesterol in plasma: a marker of cholesterol turnover in neurodegenerative diseases". Biochimie. 95 (3): 595–612. doi:10.1016/j.biochi.2012.09.025. PMID 23041502.
  12. Bandaru VV, Haughey NJ (2014). "Quantitative detection of free 24S-hydroxycholesterol, and 27-hydroxycholesterol from human serum". BMC Neurosci. 15: 137. doi:10.1186/s12868-014-0137-z. PMC 4304132. PMID 25539717.
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