STARD4
Template:PBB StAR-related lipid transfer protein 4 (STARD4) is a soluble protein involved in cholesterol transport. It can transfer up to 7 sterol molecules per minute between artificial membranes.[1]
Function
STARD4 may regulate cholesterol levels in many cells, including in the liver. STARD4 has specifically been linked to the movement of cholesterol to the endoplasmic reticulum. The protein is associated with the endoplasmic reticulum and lipid droplets.[2] Increases in the protein relate to cell stress.[3]
High levels of STARD4 increases the synthesis of bile acids and cholesterol esters in liver hepatocytes.[4] Reductions in cholesterol synthesis by cells increase STARD4 levels while StarD4 declines in mice fed a high cholesterol diet.[5][6]
Increases in levels of either master gene regulator SREBP-1a or SREBP2, which both promote the production of proteins involved in cholesterol synthesis, increase StarD4 levels in mouse liver.[7] Conversely, increased STARD4 increases active SREBP2 levels.
Loss of the protein in mice has little effect.[8] Mice without functional STARD4 weigh less and females tend to have lower cholesterol profiles. The most dramatic change observed to date is a reduction in NPC-1, a protein involved in bringing cholesterol into cells.
Structure
The protein is 205 amino acids long in the human (224 in the mouse) and almost entirely consists of a StAR-related transfer (START) domain. It also lends its name to the subgroup of START domain proteins it is part of, StarD4. This subfamily includes STARD5 and STARD6 and is closely related to the StarD1/D3 group.
References
- ^ Mesmin B, Pipalia NH, Lund FW, Ramlall TF, Sokolov A, Eliezer D, Maxfield FR (2011). "STARD4 abundance regulates sterol transport and sensing". Mol Biol Cell. 22 (21): 4004–15. doi:10.1091/mbc.E11-04-0372. PMC 3204063. PMID 21900492.
{{cite journal}}: Cite has empty unknown parameter:|month=(help)CS1 maint: multiple names: authors list (link) - ^ Rodriguez-Agudo D, Calderon-Dominguez M, Ren S, Marques D, Redford K, Medina-Torres MA, Hylemon P, Gil G, Pandak WM (October 2011). "Subcellular localization and regulation of StarD4 protein in macrophages and fibroblasts". Biochim Biophys Acta. 1811 (10): 597–606. doi:10.1016/j.bbalip.2011.06.028. PMC 3156897. PMID 21767660.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Yamada S, Yamaguchi T, Hosoda A, Iwawaki T, Kohno K (May 2006). "Regulation of human STARD4 gene expression under endoplasmic reticulum stress". Biochem Biophys Res Commun. 343 (4): 1079–85. doi:10.1016/j.bbrc.2006.03.051. PMID 16579971.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Rodriguez-Agudo D, Ren S, Wong E, Marques D, Redford K, Gil G, Hylemon P, Pandak WM (July 2008). "Intracellular cholesterol transporter StarD4 binds free cholesterol and increases cholesteryl ester formation". J Lipid Res. 49 (7): 1409–19. doi:10.1194/jlr.M700537-JLR200. PMC 2431108. PMID 18403318.
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link) - ^ Soccio RE, Adams RM, Maxwell KN, Breslow JL (March 2005). "Differential Gene Regulation of StarD4 and StarD5 Cholesterol Transfer Proteins: Activation of StARD4 by sterol regulatory element-binding protein-2 and StARD5 by endoplasmic reticulum stress". J Biol Chem. 280 (4): 19410–8. doi:10.1074/jbc.M501778200. PMID 15760897.
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link) - ^ Soccio RE, Adams RM, Romanowski MJ, Sehayek E, Burley SK, Breslow JL (May 2002). "The cholesterol-regulated StarD4 gene encodes a StAR-related lipid transfer protein with two closely related homologues, StarD5 and StarD6". Proc Natl Acad Sci U S A. 99 (10): 6943–8. doi:10.1073/pnas.052143799. PMC 124508. PMID 12011452.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Horton JD, Shah NA, Warrington JA, Anderson NN, Park SW, Brown MS, Goldstein JL (October 2003). "Combined analysis of oligonucleotide microarray data from transgenic and knockout mice identifies direct SREBP target genes". Proc Natl Acad Sci U S A. 100 (21): 12027–32. doi:10.1073/pnas.1534923100. PMC 218707. PMID 14512514.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Riegelhaupt JJ, Waase MP, Garbarino J, Cruz DE, Breslow JL (May 2010). "Targeted disruption of steroidogenic acute regulatory protein D4 leads to modest weight reduction and minor alterations in lipid metabolism". J Lipid Res. 51 (5): 1134–43. doi:10.1194/jlr.M003095. PMC 2853440. PMID 19965609.
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link)