TY - JOUR
T1 - Altered function and structure of low-density lipoprotein receptor in compactin (ML236B)-resistant mutants of Chinese hamster cells
AU - Takashi, Yoshida
AU - Akihiko, Yoshimura
AU - Mayumi, Ono
AU - Shigeaki, Hori
AU - Michinori, Waki
AU - Michihiko, Kuwano
N1 - Funding Information:
We thank Dr. M. Krieger (M.I.T.) for his kind gift of anti-NH, antibody and we also thank Dr. D.W. Russell (University of Texas Health Science Center) for his kind gift of total human cDNA for LDL receptor. We also thank Dr. D. Schlessinger (Washington University) and Dr. Y. Ikehara (Fukuoka University) for reading this paper. This work is supported by a grant-in-aid from the Ministry of Education, Science and Culture, Japan.
PY - 1987/10/17
Y1 - 1987/10/17
N2 - Mutants resistant to compactin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, have been previously isolated from the Chinese hamster V79 cell line. Two compactin-resistant mutants, MF-1 and MF-2, show altered responses to human low-density lipoprotein (LDL). Accumulation of fluorescentlabeled LDL was much reduced. Ligand blotting showed LDL receptor activity in MF-1 and MF-2 cells of about one half to one third that of V79. Internalization and degradation of LDL in MF-1 or MF-2 cells were about one tenth those in V79 cells, suggesting that the LDL binding as well as the LDL internalization of the compactin-resistant clones was altered. Down-regulation of LDL receptor activity as well as hydroxymethylglutaryl CoA reductase was observed in V79 cells treated with LDL, while there appeared to be much less down-regulation in MF-1 and MF-2 cells. Using anti-LDL receptor antibody, MF-1 and MF-2 cells were found to produce smaller-sized mature forms of LDL receptor: the molecular mass of the mutant LDL receptor was 3-5 kDa smaller than that of the parental LDL receptor. Altered O-linked oligosaccharides or amino acid sequence might account for the decreased molecular mass and aberrant properties of the LDL receptor in MF-1 and MF-2.
AB - Mutants resistant to compactin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, have been previously isolated from the Chinese hamster V79 cell line. Two compactin-resistant mutants, MF-1 and MF-2, show altered responses to human low-density lipoprotein (LDL). Accumulation of fluorescentlabeled LDL was much reduced. Ligand blotting showed LDL receptor activity in MF-1 and MF-2 cells of about one half to one third that of V79. Internalization and degradation of LDL in MF-1 or MF-2 cells were about one tenth those in V79 cells, suggesting that the LDL binding as well as the LDL internalization of the compactin-resistant clones was altered. Down-regulation of LDL receptor activity as well as hydroxymethylglutaryl CoA reductase was observed in V79 cells treated with LDL, while there appeared to be much less down-regulation in MF-1 and MF-2 cells. Using anti-LDL receptor antibody, MF-1 and MF-2 cells were found to produce smaller-sized mature forms of LDL receptor: the molecular mass of the mutant LDL receptor was 3-5 kDa smaller than that of the parental LDL receptor. Altered O-linked oligosaccharides or amino acid sequence might account for the decreased molecular mass and aberrant properties of the LDL receptor in MF-1 and MF-2.
KW - Compactin-resistant mutant
KW - Endocytosis
KW - Hydroxymethylglutaryl-CoA reductase (Chinese hamster cells)
KW - LDL receptor
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U2 - 10.1016/0005-2760(87)90086-5
DO - 10.1016/0005-2760(87)90086-5
M3 - Article
C2 - 3663697
AN - SCOPUS:0023270883
VL - 921
SP - 575
EP - 586
JO - BBA - Specialised Section On Lipids and Related Subjects
JF - BBA - Specialised Section On Lipids and Related Subjects
SN - 1388-1981
IS - 3
ER -