Low-density-lipoprotein-receptor mRNA content of fibroblasts from normal and familial hypercholesterolaemic subjects.
The amount of mRNA for the low-density-lipoprotein (LDL) receptor in cultured human fibroblasts was estimated by hybridization of the poly(A)-rich RNA fraction with a DNA probe, using the recovery of beta-actin mRNA to correct for losses. During incubation of the cells with lipoprotein-deficient serum (LPDS) both the LDL-receptor mRNA content and the rate of receptor protein synthesis increased fourfold during the first 16 h and then fell by approximately 50% during the next 24 h. The content of beta-actin mRNA fell by a similar amount, so that the ratio of receptor/beta-actin mRNAs rose and then remained constant. The fall in beta-actin mRNA content during incubation with LPDS was not prevented by the addition of cholesterol to the medium. In cells from a homozygous familial hypercholesterolaemic (FH) subject that bound 20% of the normal amount of LDL, the content of LDL-receptor mRNA and the changes during incubation with LPDS or free sterols were similar to normal. Cells from a familial hypercholesterolaemic subject that produced no immunodetectable receptor protein produced a small amount of receptor mRNA of apparently normal size which responded in the same way as in normal cells to LPDS and free sterols.
Knight
B L
BL
Medical Research Council Lipoprotein Team, Hammersmith Hospital, London, England.
Patel
D D
DD
Gavigan
S J
SJ
Soutar
A K
AK
D000199:Actins / Q000032:analysis; D002478:Cells, Cultured; D002845:Chromatography / Q000379:methods; D015342:DNA Probes; D004586:Electrophoresis / Q000379:methods; D005347:Fibroblasts / Q000032:analysis*; D006720:Homozygote; D006801:Humans; D006938:Hyperlipoproteinemia Type II / Q000235:genetics / Q000378:metabolism*; D008214:Lymphocytes / Q000032:analysis; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000032:analysis; D015347:RNA Probes; D012333:RNA, Messenger / Q000032:analysis*; D011973:Receptors, LDL / Q000032:analysis* / Q000096:biosynthesis
D000199:Actins; D015342:DNA Probes; D015347:RNA Probes; D012333:RNA, Messenger; D011973:Receptors, LDL; D011061:Poly A