Transcription factors and age-related decline in apolipoprotein A-I expression

From Beats to Metabolism: the Heart at the Core of Interorgan Metabolic Cross Talk

The heart, once considered a mere blood pump, is now recognized as a multifunctional metabolic and endocrine organ. Its function is tightly regulated by various metabolic processes, at the same time it serves as an endocrine organ, secreting bioactive molecules that impact systemic metabolism. In recent years, research has shed light on the intricate interplay between the heart and other metabolic organs, such as adipose tissue, liver, and skeletal muscle. The metabolic flexibility of the heart and its ability to switch between different energy substrates play a crucial role in maintaining cardiac function and overall metabolic homeostasis. Gaining a comprehensive understanding of how metabolic disorders disrupt cardiac metabolism is crucial, as it plays a pivotal role in the development and progression of cardiac diseases. The emerging understanding of the heart as a metabolic and endocrine organ highlights its essential contribution to whole body metabolic regulation and offers new insights into the pathogenesis of metabolic diseases, such as obesity, diabetes, and cardiovascular disorders. In this review, we provide an in-depth exploration of the heart's metabolic and endocrine functions, emphasizing its role in systemic metabolism and the interplay between the heart and other metabolic organs. Furthermore, emerging evidence suggests a correlation between heart disease and other conditions such as aging and cancer, indicating that the metabolic dysfunction observed in these conditions may share common underlying mechanisms. By unraveling the complex mechanisms underlying cardiac metabolism, we aim to contribute to the development of novel therapeutic strategies for metabolic diseases and improve overall cardiovascular health.

Vascular Aging in the Invertebrate Chordate, Botryllus schlosseri

Vascular diseases affect over 1 billion people worldwide and are highly prevalent among the elderly, due to a progressive deterioration of the structure of vascular cells. Most of our understanding of these age-related cellular changes comes from in vitro studies on human cell lines. Further studies of the mechanisms underlying vascular aging in vivo are needed to provide insight into the pathobiology of age-associated vascular diseases, but are difficult to carry out on vertebrate model organisms. We are studying the effects of aging on the vasculature of the invertebrate chordate, Botryllus schlosseri. This extracorporeal vascular network of Botryllus is transparent and particularly amenable to imaging and manipulation. Here we use a combination of transcriptomics, immunostaining and live-imaging, as well as in vivo pharmacological treatments and regeneration assays to show that morphological, transcriptional, and functional age-associated changes within vascular cells are key hallmarks of aging in B. schlosseri, and occur independent of genotype. We show that age-associated changes in the cytoskeleton and the extracellular matrix reshape vascular cells into a flattened and elongated form and there are major changes in the structure of the basement membrane over time. The vessels narrow, reducing blood flow, and become less responsive to stimuli inducing vascular regression. The extracorporeal vasculature is highly regenerative following injury, and while age does not affect the regeneration potential, newly regenerated vascular cells maintain the same aged phenotype, suggesting that aging of the vasculature is a result of heritable epigenetic changes.

Disrupting the DREAM transcriptional repressor complex induces apolipoprotein overexpression and systemic amyloidosis in mice

DREAM (Dp, Rb-like, E2F, and MuvB) is a transcriptional repressor complex that regulates cell proliferation, and its loss causes neonatal lethality in mice. To investigate DREAM function in adult mice, we used an assembly-defective p107 protein and conditional deletion of its redundant family member p130. In the absence of DREAM assembly, mice displayed shortened survival characterized by systemic amyloidosis but no evidence of excessive cellular proliferation. Amyloid deposits were found in the heart, liver, spleen, and kidneys but not the brain or bone marrow. Using laser-capture microdissection followed by mass spectrometry, we identified apolipoproteins as the most abundant components of amyloids. Intriguingly, apoA-IV was the most detected amyloidogenic protein in amyloid deposits, suggesting apoA-IV amyloidosis (AApoAIV). AApoAIV is a recently described form, whereby WT apoA-IV has been shown to predominate in amyloid plaques. We determined by ChIP that DREAM directly regulated Apoa4 and that the histone variant H2AZ was reduced from the Apoa4 gene body in DREAM's absence, leading to overexpression. Collectively, we describe a mechanism by which epigenetic misregulation causes apolipoprotein overexpression and amyloidosis, potentially explaining the origins of nongenetic amyloid subtypes.

Proteomic profiling of archaeological human bone

Ancient protein analysis provides clues to human life and diseases from ancient times. Here, we performed shotgun proteomics of human archeological bones for the first time, using rib bones from the Hitotsubashi site (AD 1657-1683) in Tokyo, called Edo in ancient times. The output data obtained were analysed using Gene Ontology and label-free quantification. We detected leucocyte-derived proteins, possibly originating from the bone marrow of the rib. Particularly prevalent and relatively high expression of eosinophil peroxidase suggests the influence of infectious diseases. This scenario is plausible, considering the overcrowding and unhygienic living conditions of the Edo city described in the historical literature. We also observed age-dependent differences in proteome profiles, particularly for proteins involved in developmental processes. Among them, alpha-2-HS-glycoprotein demonstrated a strong negative correlation with age. These results suggest that analysis of ancient proteins could provide a useful indicator of stress, disease, starvation, obesity and other kinds of physiological and pathological information.

FADS2 genotype influences whole-body resting fat oxidation in young adult men

Considerable evidence supports an association between fatty acid desaturase 2 (FADS2) polymorphisms and the efficiency of converting alpha-linolenic acid (ALA) into eicosapentaenoic acid (EPA) via the desaturation-elongation pathway. However, ALA conversion into EPA represents only 1 of the metabolic fates for this essential fatty acid, as ALA is also highly oxidized. This study demonstrates for the first time that genetic variation in FADS2 (rs174576) is not only associated with the activity of the desaturation-elongation pathway, but also whole-body fat oxidation.

Blood plasma protein and lipid profile changes in calves during the first week of life

The present study was undertaken to determine blood plasma protein and lipid profile changes in healthy Polish Holstein-Fresian calves of Black-and-White variety. Blood was drawn immediately after birth, before first colostrum intake and at the 3rd, 6th, 12th, 24th, 36th, 48th and 72nd hour of life. Subsequent four blood samples were collected at 24 hour intervals until the 7th day of life. Plasma proteins within the isoelectric point ranging from 3.0 to 10.0 were separated using high resolution two-dimensional electrophoresis. Among the 74 protein spots detected and analyzed, 16 were significantly altered during the first week of life. Differentially expressed spots were excised from the gels and subjected to peptide mass fingerprinting using MALDI-TOF MS. In total, 12 spots were successfully identified, which correspond to three proteins, namely: apolipoprotein A-I, apolipoprotein A-IV and fibrinogen gamma-B chain. A gradual increase in plasma triglyceride, total cholesterol, HDL and LDL cholesterol values was shown during the first seven days of calves life. The lowest concentration of these indicators were observed at birth and was followed by a rapid increase during the first week of postnatal life. These changes appear to be related to the transition in energy sources, from a maternal nutrient supply comprising mainly carbohydrates and amino acids to a diet which was rich in fat - colostrum and milk. This was reflected by the intense up-regulation of plasma proteins related with lipid transport and lipoprotein metabolism during the first week of life.

Can proteomics yield insight into aging aorta?

The aging aorta exhibits structural and physiological changes that are reflected in the proteome of its component cells types. The advance in proteomic technologies has made it possible to analyze the quantity of proteins associated with the natural history of aortic aging. These alterations reflect the molecular and cellular mechanisms of aging and could provide an opportunity to predict vascular health. This paper focuses on whether discoveries stemming from the application of proteomic approaches of the intact aging aorta or vascular smooth muscle cells can provide useful insights. Although there have been limited studies to date, a number of interesting proteins have been identified that are closely associated with aging in the rat aorta. Such proteins, including milk fat globule-EGF factor 8, matrix metalloproteinase type-2, and vitronectin, could be used as indicators of vascular health, or even explored as therapeutic targets for aging-related vascular diseases.

GATA6 and FOXA2 regulate Wnt6 expression during extraembryonic endoderm formation

One of the earliest epithelial-to-mesenchymal transitions in mouse embryogenesis involves the differentiation of inner cell mass cells into primitive and then into parietal endoderm. These processes can be recapitulated in vitro using F9 teratocarcinoma cells, which differentiate into primitive endoderm when treated with retinoic acid (RA) and into parietal endoderm with subsequent treatment with dibutyryl cyclic adenosine monophosphate (db-cAMP). Our previous work on how primitive endoderm develops revealed that the Wnt6 gene is upregulated by RA, leading to the activation of the canonical WNT-β-catenin pathway. The mechanism by which Wnt6 is regulated was not determined, but in silico analysis of the human WNT6 promoter region had suggested that the GATA6 and FOXA2 transcription factors might be involved [1]. Subsequent analysis determined that both Gata6 and Foxa2 mRNA are upregulated in F9 cells treated with RA or RA and db-cAMP. More specifically, overexpression of Gata6 or Foxa2 alone induced molecular and morphological markers of primitive endoderm, which occurred concomitantly with the upregulation of the Wnt6 gene. Gata6- or Foxa2-overexpressing cells were also found to have increased levels in T-cell factor (TCF)-dependent transcription, and when these cells were treated with db-cAMP, they developed into parietal endoderm. Chromatin immunoprecipitation analysis revealed that GATA6 and FOXA2 were bound to the Wnt6 promoter, and overexpression studies showed that these transcription factors were sufficient to switch on the gene expression of a Wnt6 reporter construct. Together, these results provide evidence for the direct regulation of Wnt6 that leads to the activation of the canonical WNT-β-catenin pathway and subsequent induction of primitive extraembryonic endoderm.

Down-regulation of hepatic nuclear factor 4alpha on expression of human hepatic stimulator substance via its action on the proximal promoter in HepG2 cells

hHSS (human hepatic stimulator substance) stimulates hepatocyte growth. To understand the mechanism controlling hHSS expression, we analysed the proximal promoter activity and identified two regulatory regions (-212/-192 and -152/-132) that were important for transcription in HepG2 cells. Using the luciferase reporter assay, gel-shift experiments and ChIP (chromatin immunoprecipitation), we found that the transcription factors HNF4alpha (hepatocyte nuclear factor 4alpha) and Sp1 (stimulating protein-1) were essential for hHSS promoter activity and could directly bind to regions -209/-204 and -152/-145 respectively. We also confirmed that activation and repression of hHSS transcription induced by Sp1 and HNF4alpha resulted from binding of these factors to these two cis-elements respectively. Overexpression of HNF4alpha led to a dramatic repression of the promoter activity and, in contrast, the activity was markedly elevated by overexpression of Sp1. Furthermore, overexpression of HNF4alpha1, one of the HNF4alpha isoforms, resulted in a dramatic suppression of the promoter activity. Moreover, repression of HNF4alpha expression by siRNA (small interfering RNA) remarkably enhanced the hHSS mRNA level. It has been reported previously that expression of HNF4alpha is functionally regulated by dexamethasone. To further confirm the transcriptional control of HNF4alpha on hHSS, we tested the effect of dexamethasone on hHSS transcription in HepG2 cells. In the present study we have demonstrated that the expression of the hHSS gene was down-regulated at the transcriptional level by dexamethasone in HepG2 cells. A deletion and decoy assay revealed that binding of HNF4alpha to nucleotides -209/-204 was responsible for the suppression of hHSS promoter activity by dexamethasone. Increases in the HNF4alpha-binding activity and expression were simultaneously observed in an electrophoretic mobility-shift assay and Western blot analysis. These results suggested that Sp1 activates hHSS basal expression, but HNF4alpha inhibits hHSS gene expression.

Clock mutation facilitates accumulation of cholesterol in the liver of mice fed a cholesterol and/or cholic acid diet

Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and catabolic enzymes such as cytochrome P-450, family 7, subfamily A, and polypeptide 1 (CYP7A1). Since a circadian clock controls the gene expression of these enzymes, these genes exhibit circadian rhythm in the liver. In this study, we examined the relationship between a diet containing CH and/or cholic acid (CA) and the circadian regulation of Hmgcr, low-density lipoprotein receptor (Ldlr), and Cyp7a1 gene expression in the mouse liver. A 4-wk CA diet lowered and eventually abolished the circadian expression of these genes. Not only clock genes such as period homolog 2 (Drosophila) (Per2) and brain and muscle arnt-like protein-1 (Bmal1) but also clock-controlled genes such as Hmgcr, Ldlr, and Cyp7a1 showed a reduced and arrhythmic expression pattern in the liver of Clock mutant mice. The reduced gene expression of Cyp7a1 in mice fed a diet containing CA or CH + CA was remarkable in the liver of Clock mutants compared with wild-type mice, and high liver CH accumulation was apparent in Clock mutant mice. In contrast, a CH diet without CA only elevated Cyp7a1 expression in both wild-type and Clock mutant mice. The present findings indicate that normal circadian clock function is important for the regulation of CH homeostasis in the mouse liver, especially in conjunction with a diet containing high CH and CA.

Differential regulation of constitutive androstane receptor expression by hepatocyte nuclear factor4alpha isoforms

Constitutive androstane receptor (CAR; NR1I3) controls the metabolism and elimination of endogenous and exogenous toxic compounds by up-regulating a battery of genes. In this work, we analyzed the expression of human CAR (hCAR) in normal liver during development and in hepatocellular carcinoma (HCC) and investigated the effect of hepatocyte nuclear factor 4alpha isoforms (HNF4alpha1 and HNF4alpha7) on the hCAR gene promoter. By performing functional analysis of hCAR 5'-deletions including mutants, chromatin immunoprecipitation in human hepatocytes, electromobility shift and cotransfection assays, we identified a functional and species-conserved HNF4alpha response element (DR1: ccAGGCCTtTGCCCTga) at nucleotide -144. Both HNF4alpha isoforms bind to this element with similar affinity. However, HNF4alpha1 strongly enhanced hCAR promoter activity whereas HNF4alpha7 was a poor activator and acted as a repressor of HNF4alpha1-mediated transactivation of the hCAR promoter. PGC1alpha stimulated both HNF4alpha1-mediated and HNF4alpha7-mediated hCAR transactivation to the same extent, whereas SRC1 exhibited a marked specificity for HNF4alpha1. Transduction of human hepatocytes by HNF4alpha7-expressing lentivirus confirmed this finding. In addition, we observed a positive correlation between CAR and HNF4alpha1 mRNA levels in human liver samples during development, and an inverse correlation between CAR and HNF4alpha7 mRNA levels in HCC. These observations suggest that HNF4alpha1 positively regulates hCAR expression in normal developing and adult livers, whereas HNF4alpha7 represses hCAR gene expression in HCC.

Orphan nuclear receptors: therapeutic opportunities in skeletal muscle

Nuclear hormone receptors (NRs) are ligand-dependent transcription factors that bind DNA and translate physiological signals into gene regulation. The therapeutic utility of NRs is underscored by the diversity of drugs created to manage dysfunctional hormone signaling in the context of reproductive biology, inflammation, dermatology, cancer, and metabolic disease. For example, drugs that target nuclear receptors generate over $10 billion in annual sales. Almost two decades ago, gene products were identified that belonged to the NR superfamily on the basis of DNA and protein sequence identity. However, the endogenous and synthetic small molecules that modulate their action were not known, and they were denoted orphan NRs. Many of the remaining orphan NRs are highly enriched in energy-demanding major mass tissues, including skeletal muscle, brown and white adipose, brain, liver, and kidney. This review focuses on recently adopted and orphan NR function in skeletal muscle, a tissue that accounts for approximately 35% of the total body mass and energy expenditure, and is a major site of fatty acid and glucose utilization. Moreover, this lean tissue is involved in cholesterol efflux and secretes that control energy expenditure and adiposity. Consequently, muscle has a significant role in insulin sensitivity, the blood lipid profile, and energy balance. Accordingly, skeletal muscle plays a considerable role in the progression of dyslipidemia, diabetes, and obesity. These are risk factors for cardiovascular disease, which is the the foremost cause of global mortality (>16.7 million deaths in 2003). Therefore, it is not surprising that orphan NRs and skeletal muscle are emerging as therapeutic candidates in the battle against dyslipidemia, diabetes, obesity, and cardiovascular disease.

PGC-1beta down-regulation is associated with reduced ERRalpha activity and MCAD expression in skeletal muscle of senescence-accelerated mice

Mitochondrial dysfunction is involved in the development of aging. Here, we examined the effect of aging on the skeletal muscle expression of two isoforms of the transcriptional peroxisome proliferator-activated receptor gamma (PPARgamma) coactivator-1 (PGC-1) in an experimental murine model of accelerated aging, the senescence-accelerated mouse (SAM). The senescence-accelerated prone mice (SAM-P8) showed no changes in PGC-1alpha, but a decrease in PGC-1beta expression (52% reduction, p <.001) was observed compared to the senescence-accelerated resistant mice (SAM-R1). In agreement with the proposed role of PGC-1beta as an estrogen-related receptor (ERR) protein ligand, the expression of the ERRalpha target gene medium-chain acyl-coenzyme A dehydrogenase was strongly suppressed (85%, p <.001) in SAM-P8. The decrease in the expression of medium-chain acyl-coenzyme A dehydrogenase was consistent with the reduction in ERRalpha DNA-binding activity of SAM-P8. These findings indicate that the age-mediated decrease in PGC-1beta expression in SAM-P8 skeletal muscle affects the expression of genes involved in mitochondrial fatty acid oxidation.

The chicken ovalbumin upstream promoter-transcription factors modulate genes and pathways involved in skeletal muscle cell metabolism

The chicken ovalbumin upstream promoter-transcription factors (COUP-TFs) are "orphan" members of the nuclear hormone receptor (NR) superfamily. COUP-TFs are involved in organogenesis and neurogenesis. However, their role in skeletal muscle (and other major mass tissues) and metabolism remains obscure. Skeletal muscle accounts for approximately 40% of total body mass and energy expenditure. Moreover, this peripheral tissue is a primary site of glucose and fatty acid utilization. We utilize small interfering RNA (siRNA)-mediated attenuation of Coup-TfI and II (mRNA and protein) in a skeletal muscle cell culture model to understand the regulatory role of Coup-Tfs in this energy demanding tissue. This targeted NR repression resulted in the significant attenuation of genes that regulate lipid mobilization and utilization (including Pparalpha, Fabp3, and Cpt-1). This was coupled to reduced fatty acid beta-oxidation. Additionally we observed significant attenuation of Ucp1, a gene involved in energy expenditure. Concordantly, we observed a 5-fold increase in ATP levels in cells with siRNA-mediated repression of Coup-TfI and II. Furthermore, the expression of "classical" liver X receptor (LXR) target genes involved in reverse cholesterol transport (Abca1 and Abcg1) were both significantly repressed. Moreover, we observed that repression of the Coup-Tfs ablated the activation of Abca1, and Abcg1 mRNA expression by the selective LXR agonist, T0901317. In concordance, Coup-Tf-siRNA-transfected cells were refractory to Lxr-mediated reduction of total intracellular cholesterol levels in contrast to the negative control cells. In agreement Lxr-mediated activation of the Abca1 promoter in Coup-Tf-siRNA cells was attenuated. Collectively, these data suggest a pivotal role for Coup-Tfs in the regulation of lipid utilization/cholesterol homeostasis in skeletal muscle cells and the modulation of Lxr-dependent gene regulation.

Extravasation of plasma proteins can confound interpretation of proteomic studies of brain: A lesson from apo A-I in mesial temporal lobe epilepsy

Apolipoprotein A-I (apo A-I), a major component of high density lipoproteins, has been shown to be involved in lipid metabolism, cholesterol homeostasis and degeneration/regeneration of brain tissues and was proposed as a useful marker for the extent and severity of CNS injury. We searched for aberrant protein expression in hippocampus from patients with mesial temporal lobe epilepsy (MTLE) by an analytical method based on two-dimensional gel electrophoresis coupled with mass spectrometry (MALDI-TOF/TOF) and unambiguously identified 2 spots as apolipoprotein A-I forms in brain of MTLE patients with 7.5-fold increased levels (controls: 0.046 +/- 0.046; MTLE patients: 0.343 +/- 0.154, mean +/- SD, P = 0.003). Western blot analysis confirmed increased apo A-I levels in MTLE. Immunohistochemistry detected staining for apo A-I extracellularly in perivasal brain parenchyma, neuropil and areas with increased glial fibrillary acidic protein (GFAP) expression as well as some pyramidal neurons and subpial astrocytes. These findings indicate that the increase of apo A-I in MTLE was possibly not reflecting a pathogenetic role but was rather due to extravasates, bleedings or increase of microvascular endothelial cells known to synthesize apo A-I. Care has to be taken when protein expressional findings are to be interpreted in the presence of plasma proteins, including apo A-I, thus clearly representing a confounding factor.

Proteomic comparison between human young and old brains by two-dimensional gel electrophoresis and identification of proteins

To investigate molecular mechanisms of human brain aging, brain proteins were isolated from postmortem human young and old brains and profiled by two-dimensional gel electrophoresis (2-DE). With the help of special software, five down-regulated protein spots in two-dimensional gel electrophoresis gels of old brains were found compared with young brains, four of which was identified as a protein similar to peroxiredoxin 2 (accession-numbered as gi | 13631440), two of stathmin (phosphoprotein p19) and apolipoprotein A-I precursor (apo-AI) by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Eight common proteins, whose expressions were not altered between young and old brains, were also identified. The possible relevance of changes was analyzed. This study shows that the contribution of proteomics could be valuable in experimental gerontology field.

Sumoylation of Pdx1 is associated with its nuclear localization and insulin gene activation

Pancreatic duodenal homeobox-1 (Pdx1) is a transcription factor, and its phosphorylation is thought to be essential for activation of insulin gene expression. This phosphorylation is related to a concomitant shift in molecular mass from 31 to 46 kDa. However, we found that Pdx1 was modified by SUMO-1 (small ubiquitin-related modifier 1) in beta-TC-6 and COS-7 cells, which were transfected with Pdx1 cDNA. This modification contributed to the increase in molecular mass of Pdx1 from 31 to 46 kDa. Additionally, sumoylated Pdx1 localized in the nucleus. The reduction of SUMO-1 protein by use of RNA interference (SUMO-iRNAs) resulted in a significant decrease in Pdx1 protein in the nucleus. A 34-kDa form of Pdx1 was detected by the cells exposed to SUMO-iRNAs in the presence of lactacystin, a proteasome inhibitor. Furthermore, the reduced nuclear sumoylated Pdx1 content was associated with significant lower transcriptional activity of the insulin gene. These findings indicate that SUMO-1 modification is associated with both the localization and stability of Pdx1 as well as its effect on insulin gene activation.

Antioxidant vitamins and lipid therapy: end of a long romance?

During the past decade, the perception flourished that lipid and antioxidant therapy were 2 independent avenues for cardiovascular protection. However, studies have shown that commonly used antioxidant vitamin regimens do not prevent cardiovascular events. We found that the addition of antioxidant vitamins to simvastatin-niacin therapy substantially blunts the expected rise in the protective high density lipoprotein (HDL)2 cholesterol and lipoprotein(A-I) subfractions of HDL, with apparent adverse effects on the progression of coronary artery disease. To better understand this effect, 12 apolipoproteins, receptors, or enzymes that contribute to reverse cholesterol transport have been examined in terms of their relationship to HDL2 and lipoprotein(A-I) levels and the potential for antioxidant modulation of their gene expression. Three plausible candidate mechanisms are identified: (1) antioxidant stimulation of cholesteryl ester transfer protein expression/activity, (2) antioxidant suppression of macrophage ATP binding cassette transmembrane transporter A1 expression, and/or (3) antioxidant suppression of hepatic or intestinal apolipoprotein A-I synthesis or increase in apolipoprotein A-I catabolism. In summary, antioxidant vitamins E and C and beta-carotene, alone or in combination, do not protect against cardiovascular disease. Their use for this purpose may create a diversion away from proven therapies. Because these vitamins blunt the protective HDL2 cholesterol response to HDL cholesterol-targeted therapy, they are potentially harmful in this setting. We conclude that they should rarely, if ever, be recommended for cardiovascular protection.

ProteinChip technology: a new and facile method for the identification and measurement of high-density lipoproteins apoA-I and apoA-II and their glycosylated products in patients with diabetes and cardiovascular disease

This paper describes a ProteinChip technology for the identification and quantification of apolipoprotein profiles in crude biological samples. Expression levels of apoA-I and apoA-II and their glycosylated products were accomplished using single 1 microL plasma samples. In the present studies, strong anionic and weak cationic exchanger ProteinChips (SAX2 and WCX2 chip surfaces) were tested, and the WCX2 chip was found to be selective for specific apolipoproteins. Using the WCX2 chip and analysis via surface-enhanced laser desorption ionization mass spectrometry (SELDI-MS), apoA-I and apoA-II were separated as sharp peaks at 28 and 17 kD and did not overlap with other serum protein peaks. Since these assays can be completed on a large number of clinical samples in approximately 1 h, further development of this technique will facilitate both epidemiological studies and therapeutic trials in assessing the role of the apolipoproteins and their glycosylated products in atherosclerosis.

Combined expression of pancreatic duodenal homeobox 1 and islet factor 1 induces immature enterocytes to produce insulin

Immature rat intestinal stem cells (IEC-6) given the ability to express the transcription factor, pancreatic duodenal homeobox 1 (Pdx-1), yielded YK cells. Although these cells produced multiple enteroendocrine hormones, they did not produce insulin. Exposure of YK cells to 2 nmol/l betacellulin yielded BYK cells that showed the presence of insulin expression in cytoplasm and that secreted insulin into culture media. By examining the mechanism of differentiation in BYK cells, we found that another transcription factor, islet factor 1 (Isl-1) was newly expressed with the disappearance of Pax-6 expression in those cells after exposure to betacellulin. These results indicated that combined expression of Pdx-1 and Isl-1 in IEC-6 cells was required for the production of insulin. In fact, overexpression of both Pdx-1 and Isl-1 in IEC-6 cells (Isl-YK-12, -14, and -15 cells) gave them the ability to express insulin without exposure to betacellulin. Furthermore, implantation of the Isl-YK-14 cells into diabetic rats reduced the animals' plasma glucose levels; glucose levels dropped from 19.4 to 16.9 mmol/l 1 day after the injection of cells. As expected, the plasma insulin concentrations were 2.7 times higher in the diabetic rats injected with Isl-YK-14 cells compared to in controls. In summary, our results indicated that immature intestinal stem cells can differentiate into insulin-producing cells given the ability to express the transcription factors Pdx-1 and Isl-1.

Interaction between donor and recipient age in determining the risk of chronic renal allograft failure

OBJECTIVES

Donor age is a known risk factor for chronic allograft failure (CAF) in renal transplant recipients. We have recently shown that advanced recipient age is also a risk factor for CAF. To investigate the interaction between donor and recipient age, we analyzed 40,289 primary solitary Caucasian adult renal transplants registered at the United States Renal Data System (USRDS) from 1988 to 1997.

DESIGN

CAF was defined as allograft loss beyond 6 months posttransplantation, censored for death, recurrent disease, acute rejection, thrombosis, noncompliance, infection, or technical problems. Cox proportional hazards models were used to investigate the risk of allograft loss secondary to CAF. All models were corrected for 15 covariates including donor and recipient demographics, ischemic time, and human leukocyte antigen match. Donor and recipient age were categorized, and relative risk for allograft loss of the interaction between the obtained categorical covariates was evaluated.

SETTING

Retrospective data analysis using the USRDS.

PARTICIPANTS

All primary Caucasian renal transplant recipients from 1988 to 1997.

RESULTS

Patients aged 55 and older who received donor kidneys had a 110% increased risk of CAF (relative risk (RR) = 2.1, 95% confidence interval (CI) = 1.9-2.3, P< .001) and recipients aged 65 and older had a 90% increased risk for CAF (RR = 1.9, 95% CI = 1.61-2.1, P< .001), compared with the youngest reference groups. In addition, there was an additive and, in the long term, synergistic interaction between donor and recipient age in determining allograft loss.

CONCLUSIONS

Donor and recipient age had an independent, equivalently detrimental effect on renal allograft survival. An overall additive and, in the long term (beyond 36 months posttransplant), synergistic deleterious effect on renal allograft survival was observed for the interaction of donor and recipient age.

Study of the paraoxonase and platelet-activating factor acetylhydrolase activities with aging

The purpose of this study was to investigate, with aging, the activity of two enzymes associated to HDL and responsible for its anti-atherogenic activity; paraoxonase (PON1) and platelet-activating factor acetylhydrolase (PAF-AH). Ninety-five subjects aged between 26 and 77 years were recruited for the study. The prevalence of phenotype A, AB, and B in our subjects group was 69.47,21.05 and 9.47% respectively. Plasma as well as HDL paraoxonase activity decreased significantly with aging (r =-0.218, P < 0.039) and (r = -0.280, P < 0.006) respectively. PAF-AH activity was unchanged with aging however, we noted a negative correlation between PAF-AH and PON1 activity in HDL (r = -0.243, P < 0.02) and in LDL vs HDL (r =-0.462, P < 0.001).

Insulin production in a neuroectodermal tumor that expresses islet factor-1, but not pancreatic-duodenal homeobox 1

We studied a 60-yr-old female with a brain tumor who showed severe symptoms of hypoglycemia (plasma glucose, 2.2 mmol/L) and hyperinsulinemia (1.28 nmol/L) after radiotherapy. The cystic brain tumor contained proinsulin and insulin at concentrations of 13.6 and 1.22 nmol/L, respectively. Immunohistochemical studies showed the tumor cells were ectodermal in origin but not endodermal, based on three diagnostic features of neuroectodermal tumors 1) pseudorosette formation noted under light microscopy, 2) finding of a small number of dense core neurosecretory granules on electron microscopy, and 3) positive immunostaining for both neuronal specific enolase and protein gene product 9.5. These cells also expressed the transcription factor, neurogenin-3, NeuroD/beta 2, and islet factor I, which are believed to be transcription factors in neuroectoderm as well as in pancreatic islet cells, but not pancreatic-duodenal homeobox 1, Pax4, or Nkx2.2. In addition, they did not express glucagon, somatostatin, or glucagon-like peptide-1. Our results show the presence of proinsulin in an ectoderm cell brain tumor that does not express the homeobox gene, pancreatic-duodenal homeobox 1, but expresses other transcription factors, i.e. neurogenin3, NeuroD/beta 2, and islet factor-1, which are related to insulin gene expression in the brain tumor.

Relationship of recipient age and development of chronic allograft failure

BACKGROUND

The elderly are the fastest growing segment of the end stage renal disease (ERSD) population. Older renal transplant recipients experience fewer acute rejection episodes than do younger patients. Despite this, death censored graft survival is no better in these older transplant recipients than in younger recipients. We examined the United States Renal Data System (USRDS) database to determine whether recipient age itself has an independent effect on the development of chronic allograft failure (CAF).

METHODS

We analyzed 59,509 patients from the files of the USRDS. To determine whether age was an independent risk factor for CAF, the population was analyzed separately for Caucasians, African-Americans, and other ethnic groups. All renal transplant recipients from 1988 to 1997 were examined. Both univariate and multivariate analysis were performed using chronic allograft failure as the outcome of interest.

RESULTS

Actuarial 8-year censored graft survival was significantly decreased in the older age groups 67% for ages 18-49 vs. 61.8% for ages 50-64 vs. 50.7% for ages 65+ (P<0.001). In the multivariate analysis, recipient age was a strong and independent risk factor for the development of chronic allograft failure in Caucasians (RR 1.29 for ages 50-64, RR 1.67 for ages older than 65). These findings were reinforced by an analysis that was restricted to living donor transplants without acute rejection.

CONCLUSION

In Caucasians increased recipient age is an independent risk factor for the development of chronic renal allograft failure.