Disease relevance of Apoa4

• Obesity induced by a high-fat diet downregulates apolipoprotein A-IV gene expression in rat hypothalamus [1].
• We examined the effect of ileal infusions of lipid emulsion on mRNA levels and biosynthesis of apolipoprotein A-IV (apo A-IV) in jejunal Thiry-Vella fistulas in rats [2].
• Expression of biologically active rat apolipoprotein AIV in Escherichia coli [3].
• ApoA-IV is secreted on discrete HDL particles by the rat hepatoma cell line McA-RH7777 transfected with ApoA-IV cDNA [4].
• Among the identified proteins, apolipoprotein A-IV may protect lipid peroxidation and atherosclerosis induced by TCDD exposure and the expression level of phosphoglycerate mutase increases due to hyperthyroidism induced by TCDD exposure [5].

Psychiatry related information on Apoa4

• Increased apolipoprotein A-IV in rat mesenteric lymph after lipid meal acts as a physiological signal for satiation [6].

High impact information on Apoa4

• Altered regulation of apolipoprotein A-IV gene expression in the liver of the genetically obese Zucker rat [7].
• Suppression of food intake by apolipoprotein A-IV is mediated through the central nervous system in rats [8].
• The aim of this experiment was to investigate whether the anorectic effect of apolipoprotein A-IV (apo A-IV) after lipid feeding is mediated via the central nervous system [8].
• BACKGROUND & AIMS: We recently showed that intracisternal injection of apolipoprotein A-IV (apo A-IV), a protein produced by the small intestine in response to fat, inhibits gastric acid secretion [9].
• Mechanism of action of intracisternal apolipoprotein A-IV in inhibiting gastric acid secretion in rats [9].

Biological context of Apoa4

• Diurnal rhythm of apolipoprotein A-IV in rat hypothalamus and its relation to food intake and corticosterone [10].
• Transcriptional regulation of the apolipoprotein A-IV gene involves synergism between a proximal orphan receptor response element and a distant enhancer located in the upstream promoter region of the apolipoprotein C-III gene [11].
• When heat-inactivated plasma was incubated in the presence of a purified lecithin:cholesterol acyltransferase preparation, cholesterol esterification was restored and apolipoprotein A-IV was redistributed from the lipoprotein-free fraction to the lipoprotein fraction in such a manner that greater than 90% was present in the lipoprotein fraction [12].
• Apolipoprotein B messenger RNA editing in rat liver: developmental and hormonal modulation is divergent from apolipoprotein A-IV gene expression despite increased hepatic lipogenesis [13].
• Rat apolipoprotein AIV (apo AIV) is a 43-kDa intestinal apolipoprotein that is important in lipid metabolism and the suppression of food intake [3].

Anatomical context of Apoa4

• Apolipoprotein A-IV (apo A-IV) is a satiety protein synthesized in the small intestine and hypothalamus [10].
• Apolipoprotein A-IV (apo A-IV), a peptide expressed by enterocytes in the mammalian small intestine and released in response to long-chain triglyceride absorption, may be involved in the regulation of gastric acid secretion and gastric motility [14].
• Apolipoprotein A-IV expression is limited to intestinal and hepatic cells, suggesting a tissue specific transcriptional regulation of its gene [11].
• Cholestyramine and a fat-free diet lower apolipoprotein A-IV mRNA in jejunum and cholestyramine lowers apolipoprotein A-I mRNA in ileum of rats [15].
• ApoAIV increased progressively in parallel with the restoration of the intestinal mucosa; after 48 hours of refeeding, plasma concentrations of apo AIV were significantly correlated with jejunal villous height and protein content (P less than .01) [16].

Associations of Apoa4 with chemical compounds

• After a 4-hr, 37 degrees C incubation, greater than 90% of total plasma apolipoprotein A-IV was present in the lipoprotein fraction and the percentage of plasma cholesterol present as cholesteryl ester increased from 58% to 74% [12].
• Role of thyroid hormone in the expression of apolipoprotein A-IV and C-III genes in rat liver [17].
• The density of the DMPC/apolipoprotein A-IV particles was determined to be 1.08 g/ml and the particles were visualized by electron microscopy as discs which were 5.8 nm thick and 18.0 nm in diameter [18].
• In contrast to plasma high density lipoprotein (HDL) the hepatocyte particles contained significant concentrations of triacylglycerol and apolipoproteins of Mr greater than 100,000 and lacked apolipoprotein A-IV [19].
• When applied to the culture for 24 h at 10(-7) M, a concentration shown to inhibit cholesterol synthesis by 61%, simvastatin increased apolipoprotein BH and BL synthesis and secretion and strongly decreased apolipoprotein AI synthesis and secretion whereas apolipoprotein AIV remained unaffected [20].

Physical interactions of Apoa4

• However, by competition studies it was found that apolipoprotein A-I competed for the binding to DMPC more effectively than did apolipoprotein A-IV [18].

Regulatory relationships of Apoa4

• We tested whether exogenous peptide YY (PYY) can stimulate synthesis and lymphatic secretion of intestinal apolipoprotein AIV (apo AIV) [21].

Other interactions of Apoa4

• Concentrations of apolipoprotein A-IV and the high-molecular-weight form of apolipoprotein B were markedly high during the early suckling periods and decreased at weaning [22].
• This protocol enables the measurement of apolipoprotein concentrations that are at least 10 times lower than normally detectable; 0.2 micrograms of apolipoprotein A-IV, 0.2 micrograms of apolipoprotein A-I, and 0.8 micrograms of apolipoprotein E can be easily detected in samples of 2 ml [23].
• ApoA-IV metabolism in the rat: role of lipoprotein lipase and apolipoprotein transfer [24].
• Effect of insulin, glucagon or dexamethasone on the production of apolipoprotein A-IV in cultured rat hepatocytes [25].
• Effect of leptin on intestinal apolipoprotein AIV in response to lipid feeding [26].

Analytical, diagnostic and therapeutic context of Apoa4

• Ileal apolipoprotein A-IV mRNA tended to be lower in rats fed cholestyramine and a fat-free diet than in controls [15].
• The apolipoprotein A-IV preparation was characterized by SDS-gel electrophoresis, isoelectric focusing, amino acid analysis and immunodiffusion [18].
• Total cellular RNA, isolated from rat intestinal epithelium, was translated in a wheat germ cell-free system, and the primary translation product of apolipoprotein A-IV mRNA was purified by immunoprecipitation with monospecific antibody [27].
• We studied the effects of insulin, glucagon or dexamethasone on the production of apolipoprotein A-IV (apo A-IV) by cultured rat hepatocytes, using specific radioimmunoassay for rat apo A-IV [25].
• Intravenous infusion of hexamethonium and atropine but not propranolol diminishes apolipoprotein A-IV gene expression in rat ileum [28].

References