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Apolipoprotein E alleles in nonagenarian subjects
Abstracts/
APOLlPOPROTElN NONAGENARIAN
E ALLELES SUBJECTS
Atherosclerosis
112 (1995)
265
261-267
BINDING OF LDL FROM TWO PATIENTS WITH HOMOZYGOUS FAMILIAL DEFECTIVE APOB-100 (FDB)
LDL-RECEPTOR
IN
Rea IM’, hlcDowell IT;\@, Smye M*, Stout R\V1.MONICA Project 3, Departments of Geriatric Medicine’, Climeal Biochenustrv*. Epidemiology and Rlblic HeaIth3, The Queen’s l!nivcrWy oi 11clfasr
Gallagher
JJ, Myant
NB.
MRC
Lipoprotein
Team,
HammersmithHospital, London
These rcsulls suggest thal longevity is negative11 associated \vilh 111~E4 allele and positively associated uilh E7.
In FDB, Arg3500 is replaced by Gln in apoB, leading to defective LDL-receptor binding of LDL containing mutant apoB (mutant LDL). In heterozygotes, in whom about 70% of LDL is mutant, affinity of total LDL is 30% normal. Affinity of mutant LDL separated from heterozygotes is <5% of normal. We have identified 2 homozygotes by DNA sequencingand have measuredaffinity, for receptorsin vitro, of LDL and VLDL remnants. The patients were a 65-yr-old man with coronary heart disease (CHD) (plasma cholesterol (PC) 9.5 mmol/l before treatment, 5.5 on statin) and his 68-yr-old sister without signs of CHD (PC 12 mmolll before and 5.0 on statin). Binding at 4°C and 37°C showed affinity of apoE-free LDL from the homozygoteswas lo-15% normal; affmity of VLDL remnantswas normal. We conclude (1) affinity of mutant LDL in FDB is much reducedbut high enough for significant receptor-mediatedcatabolism; (2) normal affinity of VLDL remnants(? mediatedby apoE) permits increasedremoval of LDL precursorsif hepatic receptors are stimulated and explains responseto statin.
DIFFERENTIAL BINDING OF LDL SUBFRACTIONS TO HUMAN ARTER[AL PROTECGLYCAN.
THE STRUCTURE AND COMPOSITION OF PRE-BETA HIGH DENSITY LIPOPROTEIN
The Ap3E gene has 3 alleles coding for the the proteins apoE?-, apoW and apoW E4 has been reported to bc assoctated will1 hvpercholcsterolaemia, ischaemic heart discase and Alzhcimcrs disease. In this preltminary study, ApoE phenotype was determined by clcclrofocusmg and immunoblotting 114 >90 year old subjects and comporcd to 2071 subjects aged 30-65 years rccruitcd from the same geographical arcn by the \!‘HO MONICA (MONltcring of trends and dcte~m~!~wls in CArdlo\ :Lscttlar &vase) pro-icct. The E4 LLIICICwas rcduccd In Ihc notiagcnatian group (X2=1 1.1; p=O.O008), the E3 unchanged u hilt lhc E2 ullclc crcqucnc!. iv39 Incrcnscd (X2=4.0; p=O.O47). Allele
E2
F.3
E4
9
‘i., 75.8 80.3
%
8.3 MONICA >90 year group 12.2
15.9 7.5
41&u V, Griffin BA, Packard CJ, Shepherd J. Dept. of Pathological Biochemistry, University of Glasgow, Royal Infirmary, Glasgow, Scotland, G4 OSF. The association between small, dense LDL with coronary artery disease(CAD) may derive in part from differential binding of LDL subfractions to arterial wall pmteoglycans(AF’G). The objective of this study was to determine whether a high proportion of small, dense.LDL(LDL-III, d 1.044-1.064g/ml) within total LDL increases the latter’s binding affinity for APG. Total LDL (d. 1.0191.063g/mI) was isolated from the plasma of I6 CAD positive patients and the LDL subfraction profile determined by density gradient cenbifugation. Binding assays were performed using total LDL(O.lmg/ml apoLDL) and a standard preparation of APG containing 2Spg/ml chondmitin sulphate. The extent of AK&LDL complex formation was followed by absorbancc(at 6OOnm) after 30 minutes of incubation at 25’C. LDL-APG complex formation showed a positive association with the concentration of LDL-III within total LDL (r = 0.7 pcO.002) but a negative one with the concentration of the least dense LDL-I (r = -0.5. ~0.02) and none with intermediate LDL-II. In addition the LDL-I/III ratio was negatively associated with APG binding (r = -0.66, pcO.005). In conclusion, the concentration of LDL-III within total LDL was shown to be the most significant determinant of LDL-APC complex formation. These findings demonstrate a potentially pmatherogenic property of raised LDL-III and highlight the important mle of .$PG as a sequestmnt of small, dense LDL in the arterial intima-media.
MI O’Kane, RA Aitcheson. CM Maguire. ‘DP Nicholls, ER Trimble. Department of Clinical Biochemistry. The Queen’s University of Belfast and ‘The Royal Victoria Hospital Belfast On account of its lability and low concentration there has been difficulty in defining (I) fhe struclure and composition and (2) /he relationship 10 olphn HDL, of pre-beta HDL whose importance lies in its possible role as a primary acceptor of cell cholesterol Using a sensitive chemiluminescent assay we reappraised molecular weight, protein and lipid composition. Molecular weight was assigned by gel filtration chromatography of plasma: pre-beta HDL eluted as two fractions, 44kDa and 78kDn. comprising two thirds and one third of total pre-beta HDL respectively. The protein and lipid composition was studied in plasma pre-beta HDL purified by immunoaff~nity chromatography/agarose electrophoresis and was found to contain ape AI [28kDa]as the sole protein component together with phospholipid 0.52 (0.2). cholesterol ester 0.15 (0.07 ), and free cholesterol 0. I (0.02) mmol/g protem, mean (SD). Thus. 44kDa pre-beta HDL may contain a single apo AI molecule and 78kDa prc-beta HDL one or two apo AI molecules. Basic apo AI pro-proteins AI-l and AI-2 [ - 10% of apo AI in alpha HDL] were absent from pre-beta HDL. The apo AI in prc-beta HDL, therefore, cannot be the sole precursor of apo AI in alpha HDL.
APOLlPOPROTElN NONAGENARIAN
E ALLELES SUBJECTS
Atherosclerosis
112 (1995)
265
261-267
BINDING OF LDL FROM TWO PATIENTS WITH HOMOZYGOUS FAMILIAL DEFECTIVE APOB-100 (FDB)
LDL-RECEPTOR
IN
Rea IM’, hlcDowell IT;\@, Smye M*, Stout R\V1.MONICA Project 3, Departments of Geriatric Medicine’, Climeal Biochenustrv*. Epidemiology and Rlblic HeaIth3, The Queen’s l!nivcrWy oi 11clfasr
Gallagher
JJ, Myant
NB.
MRC
Lipoprotein
Team,
HammersmithHospital, London
These rcsulls suggest thal longevity is negative11 associated \vilh 111~E4 allele and positively associated uilh E7.
In FDB, Arg3500 is replaced by Gln in apoB, leading to defective LDL-receptor binding of LDL containing mutant apoB (mutant LDL). In heterozygotes, in whom about 70% of LDL is mutant, affinity of total LDL is 30% normal. Affinity of mutant LDL separated from heterozygotes is <5% of normal. We have identified 2 homozygotes by DNA sequencingand have measuredaffinity, for receptorsin vitro, of LDL and VLDL remnants. The patients were a 65-yr-old man with coronary heart disease (CHD) (plasma cholesterol (PC) 9.5 mmol/l before treatment, 5.5 on statin) and his 68-yr-old sister without signs of CHD (PC 12 mmolll before and 5.0 on statin). Binding at 4°C and 37°C showed affinity of apoE-free LDL from the homozygoteswas lo-15% normal; affmity of VLDL remnantswas normal. We conclude (1) affinity of mutant LDL in FDB is much reducedbut high enough for significant receptor-mediatedcatabolism; (2) normal affinity of VLDL remnants(? mediatedby apoE) permits increasedremoval of LDL precursorsif hepatic receptors are stimulated and explains responseto statin.
DIFFERENTIAL BINDING OF LDL SUBFRACTIONS TO HUMAN ARTER[AL PROTECGLYCAN.
THE STRUCTURE AND COMPOSITION OF PRE-BETA HIGH DENSITY LIPOPROTEIN
The Ap3E gene has 3 alleles coding for the the proteins apoE?-, apoW and apoW E4 has been reported to bc assoctated will1 hvpercholcsterolaemia, ischaemic heart discase and Alzhcimcrs disease. In this preltminary study, ApoE phenotype was determined by clcclrofocusmg and immunoblotting 114 >90 year old subjects and comporcd to 2071 subjects aged 30-65 years rccruitcd from the same geographical arcn by the \!‘HO MONICA (MONltcring of trends and dcte~m~!~wls in CArdlo\ :Lscttlar &vase) pro-icct. The E4 LLIICICwas rcduccd In Ihc notiagcnatian group (X2=1 1.1; p=O.O008), the E3 unchanged u hilt lhc E2 ullclc crcqucnc!. iv39 Incrcnscd (X2=4.0; p=O.O47). Allele
E2
F.3
E4
9
‘i., 75.8 80.3
%
8.3 MONICA >90 year group 12.2
15.9 7.5
41&u V, Griffin BA, Packard CJ, Shepherd J. Dept. of Pathological Biochemistry, University of Glasgow, Royal Infirmary, Glasgow, Scotland, G4 OSF. The association between small, dense LDL with coronary artery disease(CAD) may derive in part from differential binding of LDL subfractions to arterial wall pmteoglycans(AF’G). The objective of this study was to determine whether a high proportion of small, dense.LDL(LDL-III, d 1.044-1.064g/ml) within total LDL increases the latter’s binding affinity for APG. Total LDL (d. 1.0191.063g/mI) was isolated from the plasma of I6 CAD positive patients and the LDL subfraction profile determined by density gradient cenbifugation. Binding assays were performed using total LDL(O.lmg/ml apoLDL) and a standard preparation of APG containing 2Spg/ml chondmitin sulphate. The extent of AK&LDL complex formation was followed by absorbancc(at 6OOnm) after 30 minutes of incubation at 25’C. LDL-APG complex formation showed a positive association with the concentration of LDL-III within total LDL (r = 0.7 pcO.002) but a negative one with the concentration of the least dense LDL-I (r = -0.5. ~0.02) and none with intermediate LDL-II. In addition the LDL-I/III ratio was negatively associated with APG binding (r = -0.66, pcO.005). In conclusion, the concentration of LDL-III within total LDL was shown to be the most significant determinant of LDL-APC complex formation. These findings demonstrate a potentially pmatherogenic property of raised LDL-III and highlight the important mle of .$PG as a sequestmnt of small, dense LDL in the arterial intima-media.
MI O’Kane, RA Aitcheson. CM Maguire. ‘DP Nicholls, ER Trimble. Department of Clinical Biochemistry. The Queen’s University of Belfast and ‘The Royal Victoria Hospital Belfast On account of its lability and low concentration there has been difficulty in defining (I) fhe struclure and composition and (2) /he relationship 10 olphn HDL, of pre-beta HDL whose importance lies in its possible role as a primary acceptor of cell cholesterol Using a sensitive chemiluminescent assay we reappraised molecular weight, protein and lipid composition. Molecular weight was assigned by gel filtration chromatography of plasma: pre-beta HDL eluted as two fractions, 44kDa and 78kDn. comprising two thirds and one third of total pre-beta HDL respectively. The protein and lipid composition was studied in plasma pre-beta HDL purified by immunoaff~nity chromatography/agarose electrophoresis and was found to contain ape AI [28kDa]as the sole protein component together with phospholipid 0.52 (0.2). cholesterol ester 0.15 (0.07 ), and free cholesterol 0. I (0.02) mmol/g protem, mean (SD). Thus. 44kDa pre-beta HDL may contain a single apo AI molecule and 78kDa prc-beta HDL one or two apo AI molecules. Basic apo AI pro-proteins AI-l and AI-2 [ - 10% of apo AI in alpha HDL] were absent from pre-beta HDL. The apo AI in prc-beta HDL, therefore, cannot be the sole precursor of apo AI in alpha HDL.