Free cholesterol overloading induced smooth muscle cells death and activated both ER- and mitochondrial-dependent death pathway.
OBJECTIVE
Smooth muscle cells (SMCs) death promotes atherosclerotic lesion necrosis and plaque destabilization. We investigated the potential mechanisms of rat SMCs death in response to excess free cholesterol (FC).


RESULTS
Rat aortic SMCs were incubated with "water soluble cholesterol" and acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor Sandoz58035 to establish FC-overloading cell model. Disruption of mitochondrial network and endoplasmic reticulum (ER) was observed after 12h incubation by transient transfection. After treated for 24h, enhanced cell death was noted as detected by propidium iodide (PI) staining/flow cytometry (P<0.001 vs. control). SMCs death was associated with markedly decreased mitochondrial transmembrane potential (Deltaphim), as well as upregulation of cellular reactive oxygen species (ROS) and ER stress. We also investigated possible signaling pathways involved in excess FC-initiated cell death and found that unfolded protein response (UPR) was activated, with increased cellular Bax expression and release of mitochondrial cytochrome c.


CONCLUSIONS
Our findings suggested that FC-overloading might trigger SMCs death. Both ER- and mitochondria-based signals might be implicated in these lethal events.
Kedi
Xu
X
Dept of Biomedical Engineering, Zhejiang University, Key Laboratory of Biomedical Engineering of Ministry of Education, Zheda Road 38, Hangzhou, 310027, Zhejiang, China.
Ming
Yan
Y
Yongping
Wang
W
Yi
Yang
Y
Xiaoxiang
Zheng
Z
D000577:Amides / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D005487:Foam Cells / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D008565:Membrane Proteins / Q000378:metabolism; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D017646:Organosilicon Compounds / Q000494:pharmacology; D018384:Oxidative Stress; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D013194:Staining and Labeling / Q000379:methods; D002785:Sterol O-Acyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013997:Time Factors; D051742:Transcription Factor CHOP / Q000378:metabolism; D056811:Unfolded Protein Response; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D047392:beta-Cyclodextrins / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP
D000577:Amides; D002784:Cholesterol; D045304:Cytochromes c; D004791:Enzyme Inhibitors; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D017646:Organosilicon Compounds; D017382:Reactive Oxygen Species; D002785:Sterol O-Acyltransferase; D051742:Transcription Factor CHOP; D051028:bcl-2-Associated X Protein; D047392:beta-Cyclodextrins; C494828:Bax protein, rat; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C018551:glucose-regulated proteins; C108732:methyl-beta-cyclodextrin; C040256:SAN 58035