Introduction Directory UMM :Data Elmu:jurnal:A:Atherosclerosis:Vol153.Issue1.Nov2000:
Atherosclerosis 153 2000 23 – 35
7b-Hydroxycholesterol induces Ca
2 +
oscillations, MAP kinase activation and apoptosis in human aortic smooth muscle cells
Mikko P.S. Ares
a,
, M. Isabella Po¨rn-Ares
b
, Sara Moses
c
, Johan Thyberg
d
, Lisa Juntti-Berggren
e
, Per-Olof Berggren
e
, Anna Hultga˚rdh-Nilsson
c
, Bengt Kallin
f
, Jan Nilsson
a
a
Wallenberg Laboratory, Uni6ersity Hospital MAS, Lund Uni6ersity, S-
20502
Malmo¨, Sweden
b
Di6ision of Experimental Pathology, Uni6ersity Hospital MAS, Lund Uni6ersity, S-
20502
Malmo¨, Sweden
c
Department of Cell and Molecular Biology, Section for Connecti6e Tissue Biology, Lund Uni6ersity, P.O. Box
94
, S-
221 00
Lund, Sweden
d
Department of Cell and Molecular Biology, Karolinska Institutet, S-
17177
Stockholm, Sweden
e
Rolf Luft Center for Diabetes Research, Department of Endocrinology, Karolinska Hospital, Karolinska Institutet, S-
17176
Stockholm, Sweden
f
Department of Medicine, Atherosclerosis Research Unit, King Gustaf Vth Research Institute, Karolinska Hospital, Karolinska Institutet, S-
17176
Stockholm, Sweden Received 23 June 1999; received in revised form 25 November 1999; accepted 7 January 2000
Abstract
In the present study, we characterize the early cytotoxic effects of 7b-hydroxycholesterol, a major cytotoxin in oxidized LDL, in human aortic smooth muscle cells. Within a few minutes after addition, 7b-hydroxycholesterol induced Ca
2 +
oscillations with a frequency of : 0.3 – 0.4 min
− 1
. A few hours later, thapsigargin-sensitive Ca
2 +
pools were depleted, indicating that 7b-hydrox- ycholesterol perturbs intracellular Ca
2 +
homeostasis. The mitogen-activated protein kinases MAPKs ERK1 and ERK2 but not JNK were activated within 5 min after addition of 7b-hydroxycholesterol. The side-chain hydroxylated oxysterols 25-hydroxyc-
holesterol and 27-hydroxycholesterol were more potent in inducing apoptosis than 7b-hydroxycholesterol and cholesterol-5a,6a- epoxide, as determined by TUNEL staining. Addition of TNFa 10 ngml and IFNg 20 ngml enhanced the cytotoxicity of
oxysterols and potentiated apoptosis. The cytokines alone were not toxic to smooth muscle cells at these concentrations. 25-Hydroxycholesterol and 7b-hydroxycholesterol but not cholesterol inhibited protein synthesis at 4 – 8 h as determined by
[
35
S]methionine incorporation assay. Morphologically, oxysterol-induced cell death was characterized by disorganization of the ER and Golgi membranes. The Ca
2 +
and ERK signals preceded the ultrastructural changes induced by 7b-hydroxycholesterol. © 2000 Elsevier Science Ireland Ltd. All rights reserved.
Keywords
:
7b-Hydroxycholesterol; Ca
2 +
oscillations; MAP kinase activation www.elsevier.comlocateatherosclerosis