Allele frequencies of apolipoprotein A-I and A-II gene locus DNA polymorphisms in Boston-based whites

Allele frequencies for four restriction fragment length polymorphisms of the apolipoprotein A-I gene locus and one restriction fragment length polymorphism of apolipoprotein A-II gene locus were determined in more than 100 North American whites and are reported herein.     

Isolation, expression and characterization of a human apolipoprotein B 100-specific cDNA clone

The isolation and characterization of a human apolipoprotein B 100-specific cDNA clone (lambda gt-B1) containing a 1321 base pairs (bp) spanning insert is described. It encodes the 3'-nontranslated 281 bp long region up to the polyadenylation site and 1040 bp of the C-terminal coding region of 345 amino-acid residues of human apo B 100 and the stop codon. The lambda gt-B1 cDNA clone has been isolated from a human hepatoma cDNA expression library by immunoscreening using affinity-purified polyclonal anti apo B 100 antibodies. The nucleotide sequence of the apo B 100 insert has been determined. A part of the polypeptide sequence derived from this nucleotide sequence was identical with the amino-acid sequence obtained by protein sequencing of a purified cyanogen bromide fragment of apo B 100. The fusion protein consisting of beta-galactosidase and the 345 amino-acid residue long C-terminus of apo B 100 had an apparent molecular mass of 148 kDa in NaDodSO4 polyacrylamide gel electrophoresis. In Northern blot hybridization analysis the insert of the apo B 100-cDNA clone hybridized to a 20 to 22 kb mRNA from adult human liver.     

The isolation of a genomic clone containing the apolipoprotein CII gene and the detection of linkage disequilibrium between two common DNA polymorphisms around the gene

Summary We report the isolation of a genomic clone containing the apolipoprotein CII (apo CII) gene and 5 and 3 flanking sequences. A detailed restriction map of the gene has been constructed and DNA fragments that are unique, or low copy number sequences in the genome have been identified. One of these detects a common restriction fragment length polymorphism (RFLP) with the enzyme BglI. Marked linkage disequilibrium is observed between this RFLP and that detected with the apo CII cDNA clone, even though the two variable restriction enzyme sites are approximately 12 kb apart. However, the usefulness of the apo CII gene as a marker for linkage studies is increased by the use of both RFLPs.     

Human apolipoprotein B: identification of cDNA clones and characterization of mRNA.

Apolipoprotein B (apoB) is a major protein component of low density and very low density lipoproteins. Because of its large size and heterogeneity, molecular studies of apoB have been difficult, and its structure and regulation remain poorly understood. We now report the identification of human apoB cDNA clones by antibody screening of hepatoma libraries in the expression vector lambda gt11. Both oligo(dT) primed and random primed libraries were constructed and screened with polyclonal antibodies to intact apoB, as well as with antibodies raised against a synthetic peptide based on the limited amino acid sequence available for apoB. The identity of the clones was unambiguously established by comparisons of the cloned cDNA sequences with apoB amino acid sequences. The clones hybridize to an exceptionally large 20 kb mRNA that is present in liver and intestine but not other tissues examined, consistent with the distribution expected from protein biosynthetic studies. The properties of the mRNA have implications for the biogenesis of the multiple apoB molecular weight forms secreted by liver and intestine.     

The FIC1 gene: structure and polymorphisms in baboon

A genome scan performed on 648 pedigreed baboons to detect and localize quantitative trait loci (QTL) for lipoprotein phenotypes that are known risk factors for atherosclerosis indicated the presence of a QTL on chromosome 18q that exerts a major influence on HDL-cholesterol (HDL-C) related phenotypes. Inspection of the human gene map revealed that the familial intrahepatic cholestatis gene 1 (FIC1) maps to the homologous region of baboon chromosome 18 containing the major QTL influencing HDL-C phenotypes. FIC1 is a strong biological candidate for this QTL because HDL-C is the preferred precursor for bile acid synthesis. In this study, we cloned and sequenced FIC1 cDNA and found that it is highly conserved between human and baboon. We also sequenced FIC1 cDNAs from a panel of unrelated baboons revealing single nucleotide polymorphisms (SNPs) and a polymorphic dinucleotide repeat. None of the baboon SNPs corresponded to human FIC1 mutations associated with familial intrahepatic cholestasis or benign recurrent intrahepatic cholestasis disorders.     

Isolation and characterisation of a cDNA clone for human apolipoprotein CI and assignment of the gene to chromosome 19

Summary We have synthesised a mixed oligonucleotide 17 bases long and used it to isolate cDNA clones for apolipoprotein CI (apo CI) from an adult liver cDNA library. The partial sequence of one of these clones confirms its identity. We have used this probe and Southern blotting techniques to identify the human apo CI gene in DNA from a series of rodent x human somatic cell hybrids. Our Results provide evidence for the assignment of this gene to human chromosome 19.     

The unique role of apolipoprotein A-I in HDL remodeling and metabolism

PURPOSE OF REVIEW: To rationalize the distinctive biological behavior of apolipoprotein (apo)A-I and apoA-II in light of differences in their respective structures, properties, and physico-chemical behavior. RECENT FINDINGS: The distinctive metabolic behavior of apoA-I compared with that of apoA-II, which are revealed as differences in their interactions with the HDL receptor, scavenger receptor class B type I, can be understood in terms of their physico-chemical properties. Detergent and chaotropic perturbation of HDL unmasks properties that distinguish apoA-I from apoA-II and emulate the secondary effects of lecithin: cholesterol acyltransferase, cholesteryl ester transfer protein, and phospholipid transfer protein - the key protein factors in HDL remodeling, that is, formation of lipid-free apoA-I but not apoA-II and particle fusion. Thus, of the two major HDL apolipoproteins, apoA-I is the more plastic and labile and this difference gives apoA-I a unique physiological role that has been verified in mouse models of HDL metabolism. SUMMARY: The compositions, structures, and properties of HDL particles are important determinants of the mechanisms by which these antiatherogenic lipoproteins are metabolized. Although the plasma lipid transfer proteins and lipid-modifying enzymes are important determinants of HDL processing, the distinctive structures and properties of apoA-I and apoA-II, the two major HDL proteins, determine in different ways the thermodynamic stability of HDL - the former through its greater plasticity and the latter by its higher lipophilicity. These distinctions have been revealed by physico-chemical studies of HDL stability in the context of numerous studies of enzyme and lipid transfer activities and of the interaction of HDL with its hepatic scavenger receptor.     

Sequencing and identification of a cDNA clone for tomato polygalacturonase.

The 2a isoenzyme of tomato polygalacturonase was purified from ripe fruit and characterised. The N-terminal amino acid sequence of the protein was determined in order to identify polygalacturonase cDNA clones. The nucleotide sequence of a ripening-related cDNA (pTOM 6) was determined and found to encode the N-terminal sequence of mature polygalacturonase 2a. The complete open reading frame encodes a polypeptide of molecular weight 50,051, including a putative pre-sequence of 71 amino acids.     

Isolation and characterization of a cDNA clone for porcine thyroid peroxidase

We undertook the molecular cloning of porcine thyroid peroxidase (TPO). Four oligonucleotide probes were synthesized on the basis of amino acid sequences of 3 tryptic peptides from highly purified porcine TPO. These probes were used to screen a pig thyroid cDNA library. Seven of 16 selected clones (0.45-1.15 kb in size) reacted with all 4 probes. Nucleotide sequencing of the 1.15 kb at the 3'-end of the structural gene revealed the complementary sequence to all 4 probes as well as the nucleotides coding for the entire length of the 3 tryptic peptides. There is an open reading frame of 332 amino acid residues. On Northern blot analysis this gene codes for an mRNA species of 2.85 kb, corresponding to the anticipated size of the mRNA for the intact TPO molecule. We have therefore cloned and characterized a cDNA clone coding for approx. 36% of porcine thyroid peroxidase.     

Molecular genetic studies of gene identification for sarcopenia

Sarcopenia, which is characterized by a progressive decrease of skeletal muscle mass and function with aging, is closely related to several common diseases (such as cardiovascular and airway diseases) and functional impairment/disability. Strong genetic determination has been reported for muscle mass and muscle strength, two most commonly recognized and studied risk phenotypes for sarcopenia, with heritability ranging from 30 to 85% for muscle strength and 45–90% for muscle mass. Sarcopenia has been the subject of increasing genetic research over the past decade. This review is designed to comprehensively summarize the most important and representative molecular genetic studies designed to identify genetic factors associated with sarcopenia. We have methodically reviewed whole-genome linkage studies in humans, quantitative trait loci mapping in animal models, candidate gene association studies, newly reported genome-wide association studies, DNA microarrays and microRNA studies of sarcopenia or related skeletal muscle phenotypes. The major results of each study are tabulated for easy comparison and reference. The findings of representative studies are discussed with respect to their influence on our present understanding of the genetics of sarcopenia. This is a comprehensive review of molecular genetic studies of gene identification for sarcopenia, and an overarching theme for this review is that the currently accumulating results are tentative and occasionally inconsistent and should be interpreted with caution pending further investigation. Consequently, this overview should enhance recognition of the need to validate/replicate the genetic variants underlying sarcopenia in large human cohorts and animal. We believe that further progress in understanding the genetic etiology of sarcopenia will provide valuable insights into important fundamental biological mechanisms underlying muscle physiology that will ultimately lead to improved ability to recognize individuals at risk for developing sarcopenia and our ability to treat this debilitating condition.     

Sequencing and genetic analysis of a bovine DQA cDNA clone

The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number M90306.     

DNA polymorphisms of the apolipoprotein B and A-I/C-III genes are associated with variations of serum low density lipoprotein cholesterol level in childhood.

A number of restriction fragment length polymorphisms (RFLPs) of the apolipoprotein B (apoB) and apolipoprotein A-I/C-III(apoA-I/C-III) genes have been found to be associated with serum lipoprotein levels in many adult populations. In order to examine whether these genetic polymorphisms influence serum lipoprotein levels in childhood and adolescence, we determined the apoB XbaI and apoA-I/C-III SstI genotypes and serum lipoprotein concentrations in 307 healthy Finns aged 9 to 21 years. In the age groups of 9, 12, and 15 years, subjects homozygous for the X2 allele (the XbaI site present) of the apoB gene had mean serum low-density lipoprotein (LDL) cholesterol levels (3.69, 3.43, and 3.15 mmol/l, respectively) that were 12-20% higher than those in subjects homozygous for the absence of this allele (3.08, 3.02, and 2.80 mmol/l, respectively). This association was more significant in males than in females. At the age of 9 to 18 years, subjects carrying the S2 allele (SstI site present) of the apoA-I/C-III gene complex had an approximately 6-15% higher mean serum LDL-cholesterol level than those homozygous for its absence. The combined genotype X2+S2+ (the simultaneous presence of the X2 allele and the S2 allele) was associated with an even more marked elevation of serum LDL-cholesterol level than either allele alone. As an example, the serum LDL cholesterol concentration was 20% higher in 9-year-old subjects with at least one X2 and one S2 allele than in those without either allele (3.55 vs. 2.97 mmol/l, P less than 0.005). The S2 allele was found to be significantly more frequent in eastern than in western Finland, whereas no significant areal differences were seen in the occurrence of the X2 allele. In conclusion, genetic variations of the apoB and apoA-I/C-III gene loci influence serum lipoprotein concentrations already in childhood.     

Isolation and genetic characterization of the porcine apolipoprotein E gene

The present report describes the isolation and genetic characterization of the porcine apolipoprotein E (ape-E) gene. A single positive recombinant phage clone containing a 10·7-kb insert was isolated from a porcine genomic library, and a 4·2-kb fragment was subcloned and sequenced. The 4·2-kb fragment contained the entire apo-E gene in addition to upstream and downstream sequences (GenBank accession no. 470240). The porcine apo-E gene is made up of four exons and three introns, and encodes a preapo-E protein comprised of a signal peptide of 18 amino acids and a mature protein of 299 amino acids. The porcine apo-E gene contains a (CG)₁₃ microsatellite marker within intron three. This microsatellite is moderately polymorphic, and at least four alleles were evident at this locus among 10 animals from each of the Yorkshire, Hampshire, Landrace and Duroc breeds. Finally, localization of the porcine apo-E gene to chromosome 6 band q2·1 was determined by fluorescent in situ hybridization and confirmed by genetic linkage analysis.