Analysis of novel apolipoprotein B mutations using a modified U937 cell line LDL binding assay

Meng, Qingguo; Pajukanta, Päivi; Ilmonen, Marja; Schuster, Herbert; Schewe, Christiane; Andersson, Leif C.; Tikkanen, Matti J.

doi:10.1016/s0009-8981(96)06409-1

Cited by 4 publications

(3 citation statements)

References 19 publications

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“…Lipoproteins were prepared as described previously (8). Briefly, plasma was prepared from blood samples of normolipidemic subjects by centrifugation (3000 g).…”

Section: Preparation Of Ldl and Hdlmentioning

confidence: 99%

Expression of low and high density lipoprotein receptor genes in human adrenals

Liu

Heikkilä

Meng

et al. 2000

European Journal of Endocrinology

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Corticosteroids are synthesized from cholesterol which may arise from de novo synthesis or from the uptake of low or high density lipoproteins (LDL or HDL). In the present study, we compared the expression and regulation patterns of LDL receptor and CLA-1 (CD36 and LIMPII Analogous-1, an HDL receptor) genes in adult human adrenocortical tissues to shed more light on the relative contribution of LDL and HDL in human adrenal steroidogenesis. By screening 64 normal and pathological adrenal samples by Northern blotting, we found a positive correlation between LDL receptor and CLA-1 mRNA expression in the adrenal tissues (r = 0.547; spearman rank correlation test P < 0.01). Adrenal tissues adjacent to Cushing's adenomas contained consistently less LDL receptor and CLA-1 mRNA than normal adrenals (Mann-Whitney P < 0.05). In primary cultures of normal adrenal cells, accumulation of both LDL receptor and CLA-1 mRNAs was upregulated by ACTH in a dose-and time-dependent manner, with an earlier induction of LDL receptor than CLA-1 mRNA expression. (Bu) 2 cAMP also increased the levels of these two mRNAs. Addition of LDL, but not HDL, into the culture medium increased cortisol production in untreated adrenocortical cells. Both LDL and HDL enhanced ACTH-induced cortisol production, with the effect of LDL much stronger than that of HDL. Our data show that LDL receptor and CLA-1's expression is ACTH-dependent and occurs in parallel in human adrenal tissues. LDL rather than HDL may be used as the preferential source of cholesterol for steroidogenesis in human adult adrenocortical cells.

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“…Lipoproteins were prepared as described previously (8). Briefly, plasma was prepared from blood samples of normolipidemic subjects by centrifugation (3000 g).…”

Section: Preparation Of Ldl and Hdlmentioning

confidence: 99%

Expression of low and high density lipoprotein receptor genes in human adrenals

Liu

Heikkilä

Meng

et al. 2000

European Journal of Endocrinology

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“…The first mutation to be identified and characterized in APOB, APOB3500 now known as APOB3527, was discovered in late 1980s (9,14). In the following years, other alterations were described as p.Asn1914Ser, p.His1923Arg, p.Arg3507Trp, p.Arg3527Trp, p.Arg3558Cys, p.Trp4396Tyr and p.Ala4481Thr (9,11,(15)(16)(17); however, only p.Arg3507Trp, p.Arg3527Gln, p.Arg3558Cys, p.Trp4396Tyr were proved to be pathogenic, although there are controversial data regarding p.Arg3558Cys that seems to be influenced by environmental factors (16). The remaining variants were classified as polymorphisms (15).…”

Section: Introductionmentioning

confidence: 99%

“…In the following years, other alterations were described as p.Asn1914Ser, p.His1923Arg, p.Arg3507Trp, p.Arg3527Trp, p.Arg3558Cys, p.Trp4396Tyr and p.Ala4481Thr (9,11,(15)(16)(17); however, only p.Arg3507Trp, p.Arg3527Gln, p.Arg3558Cys, p.Trp4396Tyr were proved to be pathogenic, although there are controversial data regarding p.Arg3558Cys that seems to be influenced by environmental factors (16). The remaining variants were classified as polymorphisms (15). The penetrance of APOB mutations has been shown to be ,100% and patients with APOB mutations usually have a less-severe phenotype than FH patients due to LDLR mutations (2,14).…”

Section: Introductionmentioning

confidence: 99%

Novel functional APOB mutations outside LDL-binding region causing familial hypercholesterolaemia

Alves

Etxebarria

Soutar

et al. 2013

Human Molecular Genetics

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Familial hypercholesterolaemia (FH) is characterized by increased circulating low-density lipoprotein (LDL) cholesterol leading to premature atherosclerosis and coronary heart disease. Although FH is usually caused by mutations in LDLR, mutations in APOB and PCSK9 also cause FH but only a few mutations have been reported, APOB p.R3527Q being the most common. However, 30-80% of clinical FH patients do not present an identifiable mutation in any of the described genes. To identify the genetic cause of the hypercholesterolaemia in 65 patients without mutations in LDLR, PCSK9 or in fragments of exon 26 and 29 of APOB currently analysed, we performed whole sequencing of APOB by pyrosequencing. A total of 10 putative mutations in APOB were identified. Flow cytometry with fluorescently labelled LDL from patients and relatives showed that p.Arg1164Thr (exon 22) and p.Gln4494del (exon 29) presented a 40% decrease in internalization in lymphocytes and HepG2 cells, very similar to APOB3527. The proliferation assays with U937 cells showed reduced growth for both cases. The variant p.Tyr1247Cys was found to be neutral and other three alterations were considered polymorphisms. Our results emphasize the need to study the whole APOB in routine protocols to improve patient identification and cardiovascular risk assessment.

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