Molecular Characterization and Growth Association of Two Apolipoprotein A-Ib Genes in Common Carp (Cyprinus carpio)

Apolipoprotein A-I (ApoA-I) is functionally involved in the transportation and metabolism of lipids in vertebrates. In this study, two isoforms of apoA-Ib in common carp (Cyprinus carpio L.) were characterized. Sequence comparison and phylogenetic analysis showed that C. carpio ApoA-Ib is relatively conserved within cyprinid fishes. During embryonic development, C. carpioapoA-Ib was first expressed at the stage of multi-cells, and the highest mRNA level was observed at the stage of optic vesicle. A ubiquitous expression pattern was detected in various tissues with extreme predominance in the liver. Significantly different expression levels were observed between light and heavy body weight groups and also in the compensatory growth test. Seventeen and eight single-nucleotide polymorphisms (SNPs) were identified in matured mRNA of the C. carpioapoA-Ib.1 and apoA-Ib.2, respectively. Two of these SNPs (apoA-Ib.2-g.183A>T and apoA-Ib.2-g.1753C>T) were significantly associated with body weight and body length in two populations of common carp. These results indicate that apoA-Ib may play an important role in the modulation of growth and development in common carp.

Distribution of apolipoprotein ai-containing lipoprotein subclasses in plasma of normolipidemic subjects

The distribution of apoA-I among apoA-I-containing lipoprotein (AI-Lp) subclasses in plasma was studied by immunoblotting utilizing agarose gel matrix incorporating anti-apoA-I as the transfer medium. Nine AI-Lp subclasses were detected in the plasma of normolipidemics, with relative molecular masses ranging from 70,000 to ≥ 354,000 and diameters from 7.12 to ≥ 11.6 nm. The mass distribution of AI-Lp subclasses was significantly different between males and females, and some subclasses increased gradually with age while others decreased. There was a significant strong positive correlation between subclass 1 (M(r) 70,000–75,000) and subclass 3 (M(r) 105,000–126,000) in all subjects and age groups. Analysis of similar AI-Lp or HDL subclasses reported in the literature showed variability in the sizes reported by various workers. This stresses the need for a unified classification of such subclasses, and this work contributes to this direction. The quantitative nature of the method used in this work compared with the semiquantitative approaches used earlier makes it a better method for the study of the quantitative changes of the subclasses in various physiological and pathological states. The method helps to generate ideas for in vitro and in vivo studies of apoA-I exchange among subclasses and in vivo kinetic studies. Conclusion. Plasma level of the AILp subclasses varied quantitatively with age and gender, and strong correlations were detected between some subclasses. This work contributes to a better classification of AI-Lp subclasses according to their size. Comparison of the method used here with the methods reported in the literature revealed its advantages.

Concentrations of electrophoretic and size subclasses of apolipoprotein A-I-containing particles in human peripheral lymph

When cultured cells are exposed to plasma, the initial acceptors of unesterified cholesterol are small lipid-poor apolipoprotein A-I (apoA-I)-containing high density lipoproteins (HDLs) with pre-beta electrophoretic mobility. These are converted by lecithin:cholesterol acyltransferase into larger spheroidal cholesteryl ester-rich HDLs with alpha mobility. To study the determinants of the concentration of small pre-beta HDLs in tissue fluids, we collected prenodal peripheral lymph from 34 fasted normal men. By crossed immunoelectrophoresis, the concentration of pre-beta HDLs in lymph averaged 20% of that in plasma. On multiple regression analysis, pre-beta apoA-I concentration in lymph was directly related to pre-beta apoA-I concentration in plasma and independently to alpha apoA-I concentration in lymph. Similar results were obtained when the same apoA-I-containing particles were quantified by size exclusion chromatography. Lymph pre-beta apoA-I concentration was low in a subject with familial lecithin:cholesterol acyltransferase deficiency, despite a normal plasma pre-beta apoA-I concentration, but was normal in a subject with familial lipoprotein lipase deficiency. These results suggest that the concentration of small pre-beta HDLs in human tissue fluids is determined only in part by the transfer of pre-beta HDLs across capillary endothelium from plasma. Local production, by remodeling of spheroidal alpha HDLs in tissue fluids, may be equally important. Lipolysis of triglyceride-rich lipoproteins by lipoprotein lipase appears to have little effect.

Subclasses of LpA-I in coronary artery disease: distribution and cholesterol efflux ability

We analysed the distribution of LpA-I particles according to their molecular weight in 34 men with symptomatic coronary artery disease (CAD) and 11 men with no symptoms of CAD (control group). Using an original rapid and reproducible gradient gel electrophoresis technique, three LpA-I subclasses were defined: large (L-LpA-I), intermediate (I-LpA-I) and small LpA-I (S-LpA-I). The proportion of L-LpA-I was significantly lower in the CAD group (37.5 +/- 18.5%) than in the control group (58.9 +/- 15.0%) (P < 0.01). Conversely, a significantly (P < 0.05) higher proportion of I-LpA-I (31.9 +/- 20.7%) was observed in the CAD group compared with the control group (14.2 +/- 8.2%). Also, in the CAD group, the proportion of L-LpA-I was positively associated with the plasma level of LpA-I (P < 0.05) and, conversely, the proportion of S-LpA-I was negatively associated with LpA-I levels (P < 0.01). L-LpA-I and I-LpA-I from CAD patients and from control subjects were most effective in promoting cholesterol efflux from Fu5AH rat hepatoma cells, whereas S-LpA-I was ineffective in this regard. In conclusion, the decreased ratio in CAD patients of L-LpA-I, lipoprotein subspecies that are required for cholesterol efflux from cells, suggests a potential anti-atherogenic effect of these particles associated with the larger LpA-I subfractions.

Apolipoprotein A-II production rate is a major factor regulating the distribution of apolipoprotein A-I among HDL subclasses LpA-I and LpA-I:A-II in normolipidemic humans

HDLs are heterogeneous in their apolipoprotein composition. Apolipoprotein (apo) A-I and apoA-II are the major proteins found in HDL and form the two major HDL subclasses: those that contain only apoA-I (LpA-I) and those that contain both apoA-I and apoA-II (LpA-I:A-II). Substantial evidence indicates that these two subclasses differ in their in vivo metabolism and effect on atherosclerosis, with LpA-I the more specifically protective subfraction against atherosclerosis. The purpose of this study was to investigate the effect of apoA-I and apoA-II production and catabolism on plasma LpA-I and LpA-I:A-II levels. Fifty normolipidemic subjects (those with HDL cholesterol levels in the top and bottom tenth percentiles were excluded) underwent kinetic studies with radiolabeled apoA-I and apoA-II, and the kinetic parameters of apoA-I and apoA-II were correlated with LpA-I and LpA-I:A-II levels. ApoA-I levels were strongly correlated with apoA-I residence times and less strongly correlated with apoA-I production rates. In contrast, apoA-II levels were correlated only with apoA-II production rates and not with apoA-II residence times. Levels of apoA-I in LpA-I were correlated with apoA-I residence times, whereas levels of apoA-I in LpA-I:A-II were correlated primarily with apoA-II production rates. The fraction of apoA-I in LpA-I was highly inversely correlated with apoA-II production rate (r = -.67, P < .001). In multiple regression analysis, apoA-II production rate was the most significant independent variable determining percent apoA-I in LpA-I among all the kinetic parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of apolipoprotein A-I-containing lipoproteins in IDDM

In IDDM patients, serum high-density lipoprotein cholesterol concentrations have been reported to be normal or elevated. The spectrum of high-density lipoprotein particles is highly heterogeneous, but no data are available on the subpopulations of high-density lipoprotein in IDDM. We, therefore, studied the spectrum of high-density lipoprotein particles in 86 IDDM patients (51 men and 35 women) 37 +/- 10 yr of age and in 74 sex-, age-, and body mass index-matched healthy nondiabetic subjects. The concentrations of high-density lipoprotein and HDL2 cholesterol were higher in the IDDM group than in the control subjects (P < 0.01). The apoA-I-to-apoA-II ratio was higher in the IDDM patients than in the nondiabetic subjects (P < 0.001) because of an increased concentration of LpA-I particles (61 +/- 17 vs. 53 +/- 15, P < 0.01). LpA-I particles correlated positively with high-density lipoprotein and HDL2 cholesterol in the two groups. Postheparin plasma lipoprotein lipase activity was significantly higher in the IDDM group than in the control group (P < 0.001), whereas postheparin plasma hepatic lipase activities were similar in both groups. Plasma cholesteryl ester transfer protein activity was estimated in an in vitro isotopic assay using exogenous labeled donor (low-density) and acceptor (high-density) lipoproteins in the absence of native lipoproteins. We observed no difference in cholesteryl ester transfer protein activity between the groups, and no significant correlations existed between cholesteryl ester transfer protein activity and high-density lipoprotein subpopulations.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipoprotein subclasses in genetic studies: the Berkeley data set

In conjunction with a study examining the inheritance of LDL subclass patterns in a healthy population, measurements of lipids, lipoproteins, and lipoprotein subclasses were performed in 301 individuals in 27 kindreds. Questionnaires were used to obtain information on use of medications, hormones, cigarettes, and alcohol. Laboratory data from this study (the Berkeley data set) include measurements of LDL and HDL size subclasses by nondenaturing gradient gel electrophoresis, and measurement of apolipoprotein A-I by radial immunodiffusion.