👤 J Peter Rubin

Resource trade-off theory suggests that increased performance on a given trait comes at the cost of decreased performance on other traits. Growth data from 1889 subjects (996 girls) were used from the GrowUp1974 Gothenburg study. Energy Trade-Off (ETO) between height and weight for individuals with extreme body types was characterized using a novel ETO-Score (ETOS). Four extreme body types were defined based on height and ETOI at early adulthood: tall-slender, short-stout, short-slender, and tall-stout; their growth trajectories assessed from ages 0.5-17.5 years.A GWAS using UK BioBank data was conducted to identify gene variants associated with height, BMI, and for the first time with ETOS. Height and ETOS trajectories show a two-hit pattern with profound changes during early infancy and at puberty for tall-slender and short-stout body types. Several loci (including FTO, ADCY3, GDF5, ) and pathways were identified by GWAS as being highly associated with ETOS. The most strongly associated pathways were related to "extracellular matrix," "signal transduction," "chromatin organization," and "energy metabolism." ETOS represents a novel anthropometric trait with utility in describing body types. We discovered the multiple genomic loci and pathways probably involved in energy trade-off. Show less

Western dietary habits are partially characterized by increased uptake of fructose, which contributes to metabolic dysregulation and associated liver diseases. For example, a diet enriched with fructose drives insulin resistance and non-alcoholic fatty liver disease (NAFLD). The molecular hubs that control fructose-induced metabolic dysregulation are poorly understood. Apolipoprotein A5 (apoA5) controls triglyceride metabolism with a putative role in hepatic lipid deposition. We explored apoA5 as a rheostat for fructose-induced hepatic and metabolic disease in mammals. ApoA5 knock out (-/-) and wildtype (wt) mice were fed with high fructose diet or standard diet for 10 weeks. Afterwards, we conducted a metabolic characterization by insulin tolerance test as well as oral glucose tolerance test. Additionally, hepatic lipid content as well as transcription patterns of key enzymes and transcription factors in glucose and lipid metabolism were evaluated. Despite comparable body weight, insulin sensitivity was significantly improved in high fructose diet fed apoA5 (-/-) when compared to wildtype mice on the same diet. In parallel, hepatic triglyceride content was significantly lower in apoA5 (-/-) mice than in wt mice. No difference was seen between apoA5 (-/-) and wt mice on a standard diet. ApoA5 is involved in fructose-induced metabolic dysregulation and associated hepatic steatosis suggesting that apoA5 may be a novel target to treat metabolic diseases. Show less

Variable retention outcomes remain a significant issue in autologous fat grafting procedures. Among seemingly similar patients, using identical harvesting procedures, variability in graft retention is noted. Recent data suggest that the inherent characteristics of donor adipose tissue dictate graft healing outcomes. The goal of this study was to elucidate intrinsic qualities of human adipose tissue that confer resistance to ischemic stress to therapeutically target such mechanisms and improve overall results of fat grafts. Whole fat from 5 female patients was cultured in vitro under severe (1% O Analysis of adipocyte survival with perilipin suggested improved viability for tissue obtained from high BMI donors. Microarray data revealed a significant positive correlation for induced expression of ANGPTL4, a survival gene, and subject BMI ( The innate resilience of adipocytes to hypoxia and relative macrophage activation play a crucial role in fat graft retention. This study suggests that adipose tissue from high BMI donors demonstrates greater resistance to hypoxia-induced apoptosis associated with an increased expression of ANGPTL4. Therefore, therapeutic interventions that target this factor may improve clinical adipose graft survival. Show less

Most prostate cancers are treated, although more than 80% remain clinically insignificant and fewer than 3% are fatal. This retrospective study of 240 radical prostatectomy cases with comprehensive follow-up was a search for reliable markers of prostate cancer prognosis evaluable on biopsy specimens to enable minimization of unnecessary treatment, morbidity, and costs. Representative cancer and benign tissue from each prostatectomy specimen was made into tissue microarrays and stained with antibodies targeting 20 gene sequences. Traditional clinical and pathologic prognosticators and the 20 antibody stains were correlated with patient outcomes. By univariable analysis 4 of 20 antibodies (STMN1/stathmin 1, CYP4Z1/cytochrome p450-4z1, CDH1/E-cadherin, and Hey2), Gleason score, perineural invasion, and apical involvement were statistically significant outcome predictors for biopsy tissue. By multivariate analysis, Gleason score, Hey2, and CYP4Z1 were independently predictive. STMN1 and CDH1 were not independent of Gleason score but remain useful because marker interpretation is objective and Gleason scores often differ for biopsy and prostatectomy specimens. Show less

Peroxisome proliferator-activated receptor (PPAR)gamma is a key regulator in adipose tissue. The rare variant Pro12Ala of PPARgamma2 is associated with a decreased risk of insulin resistance. Being dietary PPARgamma ligands, conjugated linoleic acids (CLAs) received considerable attention because of their effects on body composition, cancer, atherosclerosis, diabetes, obesity and inflammation, although some effects were only demonstrated in animal trials and the results in human studies were not always consistent. In the present study effects of CLA supplementation on genome wide gene expression in adipose tissue biopsies from 11 Ala12Ala and 23 Pro12Pro men were investigated. Subjects underwent four intervention periods (4 wk) in a randomized double blind cross-over design receiving 4.25 g/d of either cis-9, trans-11 CLA, trans-10,cis-12 CLA, 1:1 mixture of both isomers or a reference linoleic acid oil preparation. After each intervention biopsies were taken, whole genome expression microarrays were applied, and genes of interest were verified by realtime PCR. The following genes of lipid metabolism were regulated by CLA: LDLR, FASN, SCD, FADS1 and UCP2 were induced, while ABCA1, CD36 and CA3 were repressed. Transcription factors PPARgamma, NFAT5, CREB5 and EBF1, the adipokine NAMPT, members of the insulin signaling cascade SORBS1 and IGF1 and IL6ST were repressed, while the adipokine THBS1 and GLUT4 involved in insulin signaling were induced. Compared to trans-10,cis-12 CLA and the CLA mixture the cis-9, trans-11 CLA isomer exerted weaker effects. Only CD36 (-1.2 fold) and THBS1 (1.5 fold) were regulated. The CLA effect on expression of PPARgamma and leptin genes depends on the PPARgamma2 genotype. The data suggest that the isomer specific influence of CLA on glucose and lipid metabolism is genotype dependent and at least in part mediated by PPARgamma. http://www.controlled-trials.com: ISRCTN91188075. Show less

ApoAV, a newly discovered apoprotein, affects plasma triglyceride level. To determine how this occurs, we studied triglyceride-rich lipoprotein (TRL) metabolism in mice deficient in apoAV. No significant difference in triglyceride production rate was found between apoa5(-/-) mice and controls. The presence or absence of apoAV affected TRL catabolism. After the injection of 14C-palmitate and 3H-cholesterol labeled chylomicrons and (125)I-labeled chylomicron remnants, the disappearance of 14C, 3H, and (125)I was significantly slower in apoa5(-/-) mice relative to controls. This was because of diminished lipolysis of TRL and the reduced rate of uptake of their remnants in apoa5(-/-) mice. Observed elevated cholesterol level was caused by increased high-density lipoprotein (HDL) cholesterol in apoa5(-/-) mice. VLDL from apoa5(-/-) mice were poor substrate for lipoprotein lipase, and did not bind to the low-density lipoprotein (LDL) receptor as well as normal very-low-density lipoprotein (VLDL). LDL receptor levels were slightly elevated in apoa5(-/-) mice consistent with lower remnant uptake rates. These alterations may be the result of the lower apoE-to-apoC ratio found in VLDL isolated from apoa5(-/-) mice. These results support the hypothesis that the absence of apoAV slows lipolysis of TRL and the removal of their remnants by regulating their apoproteins content after secretion. Show less

The apolipoprotein A5 gene (APOA5) has been repeatedly implicated in lowering plasma triglyceride levels. Since several studies have demonstrated that hyperinsulinemia is associated with hypertriglyceridemia, we sought to determine whether APOA5 is regulated by insulin. Here, we show that cell lines and mice treated with insulin down-regulate APOA5 expression in a dose-dependent manner. Furthermore, we found that insulin decreases human APOA5 promoter activity, and subsequent deletion and mutation analyses uncovered a functional E box in the promoter. Electrophoretic mobility shift and chromatin immunoprecipitation assays demonstrated that this APOA5 E box binds upstream stimulatory factors (USFs). Moreover, in transfection studies, USF1 stimulates APOA5 promoter activity, and the treatment with insulin reduced the binding of USF1/USF2 to the APOA5 promoter. The inhibition of the phosphatidylinositol 3-kinase (PI3K) pathway abolished insulin's effect on APOA5 gene expression, while the inhibition of the P70 S6 kinase pathway with rapamycin reversed its effect and increased APOA5 gene expression. Using an oligonucleotide precipitation assay for USF from nuclear extracts, we demonstrate that phosphorylated USF1 fails to bind to the APOA5 promoter. Taken together, these data indicate that insulin-mediated APOA5 gene transrepression could involve a phosphorylation of USFs through the PI3K and P70 S6 kinase pathways that modulate their binding to the APOA5 E box and results in APOA5 down-regulation. The effect of exogenous hyperinsulinemia in men showed a decrease in the plasma ApoAV level. These results suggest a potential contribution of the APOA5 gene in hypertriglyceridemia associated with hyperinsulinemia. Show less

Combined hyperlipidemia is a common disorder, characterized by a highly atherogenic lipoprotein profile and a substantially increased risk of coronary heart disease. The purpose of this study was to establish whether variations of apolipoprotein A5 (APOA5), a newly discovered gene of lipid metabolism located 30 kbp downstream of the APOA1/C3/A4 gene cluster, contributes to the transmission of familial combined hyperlipidemia (FCHL). We performed linkage and association tests on 128 families. Two independent alleles, APOA5c.56G and APOC3c.386G, of the APOA1/C3/A4/A5 gene cluster were overtransmitted in FCHL (P=0.004 and 0.007, respectively). This was paired with reduced transmission of the common APOA1/C3/A4/A5 haplotype (frequency 0.4461) to affected subjects (P=0.012). The APOA5c.56G genotype accounted for 7.3% to 13.8% of the variance in plasma triglyceride levels in probands (P<0.004). The APOC3c.386G genotypes accounted for 4.4% to 5.1% of the variance in triglyceride levels in FCHL spouses (P<0.007), suggesting that this allele marks a FCHL quantitative trait as well as representing a susceptibility locus for the condition. A combined linkage and association analysis establishes that variation at the APOA1/C3/A4/A5 gene cluster contributes to FCHL transmission in a substantial proportion of northern European families. Show less

Both the apolipoprotein A5 and C3 genes have repeatedly been shown to play an important role in determining plasma triglyceride concentrations in humans and mice. In mice, transgenic and knockout experiments indicate that plasma triglyceride levels are strongly altered by changes in the expression of either of these 2 genes. In humans, common polymorphisms in both genes have also been associated with plasma triglyceride concentrations. These similar findings raised the issue of the relationship between these 2 genes and altered triglycerides. To address this issue, we generated independent lines of mice that either overexpressed ("double transgenic") or completely lacked ("double knockout") both apolipoprotein genes. We report that both "double transgenic" and "double knockout" mice display normal triglyceride concentrations compared with overexpression or deletion of either gene alone. Furthermore, we find that human ApoAV plasma protein levels in the "double transgenic" mice are approximately 500-fold lower than human ApoCIII levels, supporting ApoAV as a potent triglyceride modulator despite its low concentration. Together, these data support that APOA5 and APOC3 independently influence plasma triglyceride concentrations but in an opposing manner. Show less

Members of the apolipoprotein gene cluster (APOA1/C3/A4/A5) on human chromosome 11q23 play an important role in lipid metabolism. Polymorphisms in both APOA5 and APOC3 are strongly associated with plasma triglyceride concentrations. The close genomic locations of these two genes as well as their functional similarity have hindered efforts to define whether each gene independently influences human triglyceride concentrations. In this study, we examined the linkage disequilibrium and haplotype structure of 49 SNPs in a 150-kb region spanning the gene cluster. We identified a total of five common APOA5 haplotypes with a frequency of greater than 8% in samples of northern European origin. The APOA5 haplotype block did not extend past the 7 SNPs in the gene and was separated from the other apolipoprotein gene in the cluster by a region of significantly increased recombination. Furthermore, one previously identified triglyceride risk haplotype of APOA5 (APOA5*3) showed no association with three APOC3 SNPs previously associated with triglyceride concentrations, in contrast to the other risk haplotype (APOA5*2), which was associated with all three minor APOC3 SNP alleles. These results highlight the complex genetic relationship between APOA5 and APOC3 and support the notion that APOA5 represents an independent risk gene affecting plasma triglyceride concentrations in humans. Show less

Genetic studies in non-human primates serve as a potential strategy for identifying genomic intervals where polymorphisms impact upon human disease-related phenotypes. It remains unclear, however, whether independently arising polymorphisms in orthologous regions of non-human primates leads to similar variation in a quantitative trait found in both species. To explore this paradigm, we studied a baboon apolipoprotein gene cluster (APOA1/C3/A4/A5) for which the human gene orthologs have well-established roles in influencing plasma HDL-cholesterol and triglyceride concentrations. Our extensive polymorphism analysis of this 68 kb gene cluster in 96 pedigreed baboons identified several haplotype blocks each with limited diversity, consistent with haplotype findings in humans. To determine whether baboons, like humans, also have particular haplotypes associated with lipid phenotypes, we genotyped 634 well-characterized baboons using 16 haplotype tagging SNPs. Genetic analysis of single SNPs, as well as haplotypes, revealed an association of APOA5 and APOC3 variants with HDL-cholesterol and triglyceride concentrations, respectively. Thus, independent variation in orthologous genomic intervals does associate with similar quantitative lipid traits in both species, supporting the possibility of uncovering human quantitative trait loci genes in a highly controlled non-human primate model. Show less

The recently discovered APOA5 gene has been shown in humans and mice to be important in determining plasma triglyceride levels, a major cardiovascular disease risk factor. apoAV represents the first described apolipoprotein where overexpression lowers triglyceride levels. Since fibrates represent a commonly used therapy for lowering plasma triglycerides in humans, we investigated their ability to modulate APOA5 gene expression and consequently influence plasma triglyceride levels. Human primary hepatocytes treated with Wy 14,643 or fenofibrate displayed a strong induction of APOA5 mRNA. Deletion and mutagenesis analyses of the proximal APOA5 promoter firmly demonstrate the presence of a functional peroxisome proliferator-activated receptor response element. These findings demonstrate that APOA5 is a highly responsive peroxisome proliferator-activated receptor alpha target gene and support its role as a major mediator for how fibrates reduce plasma triglycerides in humans. Show less

Apolipoprotein A5 (APOA5) is a newly described member of the apolipoprotein gene family whose initial discovery arose from comparative sequence analysis of the mammalian APOA1/C3/A4 gene cluster. Functional studies in mice indicated that alteration in the level of APOA5 significantly affected plasma triglyceride concentrations. Mice that overexpressed human APOA5 displayed significantly reduced triglycerides, whereas mice that lacked apoa5 had a large increase in this lipid parameter. Studies in humans have also suggested an important role for APOA5 in determining plasma triglyceride concentrations. In these experiments, polymorphisms in the human gene were found to define several common haplotypes that were associated with significant changes in triglyceride concentrations in multiple populations. Several separate clinical studies have provided consistent and strong support for the effect with 24% of whites, 35% of blacks, and 53% of Hispanics who carry APOA5 haplotypes associated with increased plasma triglyceride levels. In summary, APOA5 represents a newly discovered gene involved in triglyceride metabolism in both humans and mice whose mechanism of action remains to be deciphered. Show less

Cysteine proteinases, which are encoded by at least seven genes, play a critical role in the pathogenesis of invasive amebiasis caused by Entamoeba histolytica. The study of these enzymes has been hampered by the inability to obtain significant quantities of the individual native proteinases. We have now expressed functionally active recombinant ACP1 (EhCP3) and ACP2 (EhCP2) proteinases in baculoviral expression vectors. The purified recombinant ACP1 and ACP2 proteinases exhibited similar activities for fluorogenic peptide substrates, especially in their preference for an arginine residue at the P2 position. Although ACP1 and ACP2 are structurally cathepsin L, homology modeling revealed that the aspartic acid in the S2 pocket would result in a substrate specificity for positively charged amino acids, like cathepsin B. The hydrolysis of peptide substrates was strongly inhibited by small peptidyl inhibitors specifically designed for parasitic cysteine proteinases. Confocal and immunoelectron microscopy localization of the proteinases with monoclonal and monospecific antibodies raised to the recombinant enzymes and peptides demonstrated that ACP2 was membrane-associated while ACP1 was cytoplasmic. Following phagocytosis of erythrocytes, ACP1, as well as the membrane-associated cysteine proteinase, ACP2, were incorporated into phagocytic vesicles. These studies suggest that E. histolytica has a redundancy of cysteine proteinases for intracellular digestion and that they may be recruited from different cellular compartments to the site of digestion of phagocytosed cells. The production of active proteinases in baculovirus and large scale recombinant enzymes in bacteria should further our understanding of the role of different cysteine proteinase gene products in virulence. Show less

Since triglycerides (TG) are a major independent risk factor for coronary heart disease, understanding their genetic and environmental determinants is of major importance. Mouse models indicate an inverse relationship between levels of the newly identified apolipoprotein AV (APOAV) and TG concentrations. We have examined the relative influence of human APOA5 variants on plasma lipids, compared to the impact of variation in APOC3 and APOA4 which lie in the same cluster. Single nucleotide polymorphisms (SNPs) in APOA5 (S19W, -1131T>C) and APOA4 (T347S, Q360H) and an APOA4/A5 intergenic T>C SNP were examined in a large study of healthy middle-aged men (n=2808). APOA5 19WW and -1131CC men had 52% and 40% higher TG (P<0.003) compared to common allele homozygotes, respectively, effects which were independent and additive. APOA4 347SS men had 23% lower TG compared to TT men (P<0.002). Haplotype analysis was carried out to identify TG-raising alleles and included, in addition, four previously genotyped APOC3 SNPs (-2845T>G, -482C>T, 1100C>T, and 3238C>G). The major TG-raising alleles were defined by APOA5 W19 and APOC3 -482T. This suggests that the TG-lowering effect of APOA4 S347 might merely reflect the strong negative linkage disequilibrium with the common alleles of these variants. Thus variation in APOA5 is associated with differences in TGs in healthy men, independent of those previously reported for APOC3, while association between APOA4 and TG reflects linkage disequilibrium with these sites. The molecular mechanisms for these effects remain to be determined. Show less

The recently identified apolipoprotein A5 gene (APOA5) has been shown to play an important role in determining plasma triglyceride concentrations in humans and mice. We previously identified an APOA5 haplotype (designated APOA5*2) that is present in approximately 16% of Caucasians and is associated with increased plasma triglyceride concentrations. In this report we describe another APOA5 haplotype (APOA5*3) containing the rare allele of the single nucleotide polymorphism c.56C>G that changes serine to tryptophan at codon 19 and is independently associated with high plasma triglyceride levels in three different populations. In a sample of 264 Caucasian men and women with plasma triglyceride concentrations above the 90th percentile or below the 10th percentile, the APOA5*3 haplotype was more than three-fold more common in the group with high plasma triglyceride levels. In a second independently ascertained sample of Caucasian men and women (n=419) who were studied while consuming their self-selected diets as well as after high-carbohydrate diets and high-fat diets, the APOA5*3 haplotype was associated with increased plasma triglyceride levels on all three dietary regimens. In a third population comprising 2660 randomly selected individuals, the APOA5*3 haplotype was found in 12% of Caucasians, 14% of African-Americans and 28% of Hispanics and was associated with increased plasma triglyceride levels in both men and women in each ethnic group. These findings establish that the APOA5 locus contributes significantly to inter-individual variation in plasma triglyceride levels in humans. Together, the APOA5*2 and APOA5*3 haplotypes are found in 25-50% of African-Americans, Hispanics and Caucasians and support the contribution of common human variation to quantitative phenotypes in the general population. Show less

Comparison of genomic DNA sequences from human and mouse revealed a new apolipoprotein (APO) gene (APOAV) located proximal to the well-characterized APOAI/CIII/AIV gene cluster on human 11q23. Mice expressing a human APOAV transgene showed a decrease in plasma triglyceride concentrations to one-third of those in control mice; conversely, knockout mice lacking Apoav had four times as much plasma triglycerides as controls. In humans, single nucleotide polymorphisms (SNPs) across the APOAV locus were found to be significantly associated with plasma triglyceride levels in two independent studies. These findings indicate that APOAV is an important determinant of plasma triglyceride levels, a major risk factor for coronary artery disease. Show less

We present a clinicopathological study and the first molecular genetic analysis of a family with 2 siblings affected by a rare, protracted form of juvenile neuronal ceroid lipofuscinosis (JNCL). Molecular genetic studies showed that both siblings, in addition to being heterozygous for the 1.02-kb CLN3 deletion, a common mutation in JNCL, also had a G-to-A missense mutation at nucleotide 1,020 of the CLN3 cDNA sequence on the non-1.02-kb deletion chromosomes. This point mutation resulted in a substitution of glutamic acid by lysine at position 295 of the CLN3 protein. Thus, a single point mutation at residue 295 of the CLN3 protein in protracted JNCL may underlie the phenotype in this form, which differs from that in classic JNCL. Show less

Cln3 cyclin of the budding yeast Saccharomyces cerevisiae is a key regulator of Start, a cell cycle event in G1 phase at which cells become committed to division. The time of Start is sensitive to Cln3 levels, which in turn depend on the balance between synthesis and rapid degradation. Here we report that the breakdown of Cln3 is ubiquitin dependent and involves the ubiquitin-conjugating enzyme Cdc34 (Ubc3). The C-terminal tail of Cln3 functions as a transferable signal for degradation. Sequences important for Cln3 degradation are spread throughout the tail and consist largely of PEST elements, which have been previously suggested to target certain proteins for rapid turnover. The Cln3 tail also appears to contain multiple phosphorylation sites, and both phosphorylation and degradation of Cln3 are deficient in a cdc28ts mutant at the nonpermissive temperature. A point mutation at Ser-468, which lies within a Cdc28 kinase consensus site, causes approximately fivefold stabilization of a Cln3-beta-galactosidase fusion protein that contains a portion of the Cln3 tail and strongly reduces the phosphorylation of this protein. These data indicate that the degradation of Cln3 involves CDC28-dependent phosphorylation events. Show less