{"id":{"repo_id":"wfu","oai_identifier":"oai:wakespace.lib.wfu.edu:10339/14862"},"canonical_url":"https://search.dev.ndltd.org/etd/wfu/oai:wakespace.lib.wfu.edu:10339/14862","repository":{"repo_id":"wfu","name":"Wake Forest University","base_url":"https://wakespace.lib.wfu.edu/oai/request"},"display":{"title":"ROLE OF APOLIPOPROTEIN A-V IN TRIGLYCERIDE METABOLISM","abstract":"ApoA-V, a 366 amino acid protein synthesized by the liver, was identified in 2001 by comparative sequence analysis. The APOA5 gene is located downstream of the AI/CIII/AIV gene cluster on human chromosome 11q23. Apolipoprotein A-V (apoA-V) plasma concentrations are low (~100-200 µg/L) in comparison to other apolipoproteins, yet exert significant effects on triglyceride homeostasis. To examine the basis for its low concentration in plasma, the secretion efficiency of apoA-V was measured in stably transfected McA-RH7777 rat hepatoma cells. Pulse-chase analysis revealed that only ~20% of newly synthesized apoA-V was secreted into culture medium within two hours post-synthesis. Similar results were obtained in transfected nonhepatic (CHO) cells. In neither cell system was apoA-V found associated with cell surface heparin sulfate proteoglycans. Similar results were also obtained when endogenous mouse apoA-V was analyzed in primary hepatocytes. In addition to its low secretion efficiency, the electrophoretic banding pattern of apoA-V suggested that the protein is susceptible to intracellular proteolysis with ~60% undergoing presecretory turnover within 2 hours post-synthesis. To study the regulation of apoA-V by lipid synthesis, stably transfected McA-RH7777 cells were treated with 0.8 mM sodium oleate. The resulting increase in triglyceride synthesis resulted in a dramatic decline in apoA-V secretion, a corresponding increase in cell-associated apoA-V, but no change in total apoA-V recovery. Reduced secretion was accompanied by movement of apoA-V onto cytosolic lipid droplets, as evidenced by apoA-V's colocalization with ADRP, a lipid droplet marker, and its flotation during sucrose gradient ultracentrifugation. The possible intracellular role of apoA-V in the regulation of apoB and TG secretion was examined by generating stably transfected doxycycline-inducible McA-RH7777 cells. Upon induction of apoA-V expression, a 32% decrease in apoB-100 secretion and a 21% decrease in triglyceride secretion were observed. In addition, apoA-V expression caused a 57% decrease in the apoA-V in the d<1.006 g/ml VLDL density fraction during equilibrium density gradient ultracentrifugation. These results indicate that 1) apoA-V inefficiently traffics within the secretory pathway but that its intracellular itinerary may be regulated by changes in TG synthesis and/or accumulation and 2) part of the effect of apoA-V on TG metabolism could be exerted at the level of hepatic TG mobilization and secretion.","abstract_html":"ApoA-V, a 366 amino acid protein synthesized by the liver, was identified in 2001 by comparative sequence analysis. The APOA5 gene is located downstream of the AI/CIII/AIV gene cluster on human chromosome 11q23. Apolipoprotein A-V (apoA-V) plasma concentrations are low (~100-200 µg/L) in comparison to other apolipoproteins, yet exert significant effects on triglyceride homeostasis. To examine the basis for its low concentration in plasma, the secretion efficiency of apoA-V was measured in stably transfected McA-RH7777 rat hepatoma cells. Pulse-chase analysis revealed that only ~20% of newly synthesized apoA-V was secreted into culture medium within two hours post-synthesis. Similar results were obtained in transfected nonhepatic (CHO) cells. In neither cell system was apoA-V found associated with cell surface heparin sulfate proteoglycans. Similar results were also obtained when endogenous mouse apoA-V was analyzed in primary hepatocytes. In addition to its low secretion efficiency, the electrophoretic banding pattern of apoA-V suggested that the protein is susceptible to intracellular proteolysis with ~60% undergoing presecretory turnover within 2 hours post-synthesis. To study the regulation of apoA-V by lipid synthesis, stably transfected McA-RH7777 cells were treated with 0.8 mM sodium oleate. The resulting increase in triglyceride synthesis resulted in a dramatic decline in apoA-V secretion, a corresponding increase in cell-associated apoA-V, but no change in total apoA-V recovery. Reduced secretion was accompanied by movement of apoA-V onto cytosolic lipid droplets, as evidenced by apoA-V&#x27;s colocalization with ADRP, a lipid droplet marker, and its flotation during sucrose gradient ultracentrifugation. The possible intracellular role of apoA-V in the regulation of apoB and TG secretion was examined by generating stably transfected doxycycline-inducible McA-RH7777 cells. Upon induction of apoA-V expression, a 32% decrease in apoB-100 secretion and a 21% decrease in triglyceride secretion were observed. In addition, apoA-V expression caused a 57% decrease in the apoA-V in the d&lt;1.006 g/ml VLDL density fraction during equilibrium density gradient ultracentrifugation. These results indicate that 1) apoA-V inefficiently traffics within the secretory pathway but that its intracellular itinerary may be regulated by changes in TG synthesis and/or accumulation and 2) part of the effect of apoA-V on TG metabolism could be exerted at the level of hepatic TG mobilization and secretion.","abstract_has_math":false,"creators":["Blade, Anna"],"institution":"Wake Forest University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2009,"date_issued":"2009-05-28T15:57:27Z","date_published":"2009-05-28T15:57:27Z","updated_at":"2026-07-27T22:01:07Z","subjects":["Apolipoprotein"],"languages":["en_US"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10339/14862","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Blade, Anna"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2009-05-28T15:57:27Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2009-05-28T15:57:27Z"]},{"key":"dc:date.issued","label":"Date","values":["2009-05-28T15:57:27Z"]},{"key":"dc:publisher","label":"Institution","values":["Wake Forest University"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Apolipoprotein"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10339/14862"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["ApoA-V, a 366 amino acid protein synthesized by the liver, was identified in 2001 by comparative sequence analysis. The APOA5 gene is located downstream of the AI/CIII/AIV gene cluster on human chromosome 11q23. Apolipoprotein A-V (apoA-V) plasma concentrations are low (~100-200 µg/L) in comparison to other apolipoproteins, yet exert significant effects on triglyceride homeostasis. To examine the basis for its low concentration in plasma, the secretion efficiency of apoA-V was measured in stably transfected McA-RH7777 rat hepatoma cells. Pulse-chase analysis revealed that only ~20% of newly synthesized apoA-V was secreted into culture medium within two hours post-synthesis. Similar results were obtained in transfected nonhepatic (CHO) cells. In neither cell system was apoA-V found associated with cell surface heparin sulfate proteoglycans. Similar results were also obtained when endogenous mouse apoA-V was analyzed in primary hepatocytes. In addition to its low secretion efficiency, the electrophoretic banding pattern of apoA-V suggested that the protein is susceptible to intracellular proteolysis with ~60% undergoing presecretory turnover within 2 hours post-synthesis. To study the regulation of apoA-V by lipid synthesis, stably transfected McA-RH7777 cells were treated with 0.8 mM sodium oleate. The resulting increase in triglyceride synthesis resulted in a dramatic decline in apoA-V secretion, a corresponding increase in cell-associated apoA-V, but no change in total apoA-V recovery. Reduced secretion was accompanied by movement of apoA-V onto cytosolic lipid droplets, as evidenced by apoA-V's colocalization with ADRP, a lipid droplet marker, and its flotation during sucrose gradient ultracentrifugation. The possible intracellular role of apoA-V in the regulation of apoB and TG secretion was examined by generating stably transfected doxycycline-inducible McA-RH7777 cells. Upon induction of apoA-V expression, a 32% decrease in apoB-100 secretion and a 21% decrease in triglyceride secretion were observed. In addition, apoA-V expression caused a 57% decrease in the apoA-V in the d<1.006 g/ml VLDL density fraction during equilibrium density gradient ultracentrifugation. These results indicate that 1) apoA-V inefficiently traffics within the secretory pathway but that its intracellular itinerary may be regulated by changes in TG synthesis and/or accumulation and 2) part of the effect of apoA-V on TG metabolism could be exerted at the level of hepatic TG mobilization and secretion."]},{"key":"dc:title","label":"Title","values":["ROLE OF APOLIPOPROTEIN A-V IN TRIGLYCERIDE METABOLISM"]}]}],"canonical_facts":{"dc:creator":["Blade, Anna"],"dc:date.accessioned":["2009-05-28T15:57:27Z"],"dc:date.available":["2009-05-28T15:57:27Z"],"dc:date.issued":["2009-05-28T15:57:27Z"],"dc:description.abstract":["ApoA-V, a 366 amino acid protein synthesized by the liver, was identified in 2001 by comparative sequence analysis. The APOA5 gene is located downstream of the AI/CIII/AIV gene cluster on human chromosome 11q23. Apolipoprotein A-V (apoA-V) plasma concentrations are low (~100-200 µg/L) in comparison to other apolipoproteins, yet exert significant effects on triglyceride homeostasis. To examine the basis for its low concentration in plasma, the secretion efficiency of apoA-V was measured in stably transfected McA-RH7777 rat hepatoma cells. Pulse-chase analysis revealed that only ~20% of newly synthesized apoA-V was secreted into culture medium within two hours post-synthesis. Similar results were obtained in transfected nonhepatic (CHO) cells. In neither cell system was apoA-V found associated with cell surface heparin sulfate proteoglycans. Similar results were also obtained when endogenous mouse apoA-V was analyzed in primary hepatocytes. In addition to its low secretion efficiency, the electrophoretic banding pattern of apoA-V suggested that the protein is susceptible to intracellular proteolysis with ~60% undergoing presecretory turnover within 2 hours post-synthesis. To study the regulation of apoA-V by lipid synthesis, stably transfected McA-RH7777 cells were treated with 0.8 mM sodium oleate. The resulting increase in triglyceride synthesis resulted in a dramatic decline in apoA-V secretion, a corresponding increase in cell-associated apoA-V, but no change in total apoA-V recovery. Reduced secretion was accompanied by movement of apoA-V onto cytosolic lipid droplets, as evidenced by apoA-V's colocalization with ADRP, a lipid droplet marker, and its flotation during sucrose gradient ultracentrifugation. The possible intracellular role of apoA-V in the regulation of apoB and TG secretion was examined by generating stably transfected doxycycline-inducible McA-RH7777 cells. Upon induction of apoA-V expression, a 32% decrease in apoB-100 secretion and a 21% decrease in triglyceride secretion were observed. In addition, apoA-V expression caused a 57% decrease in the apoA-V in the d<1.006 g/ml VLDL density fraction during equilibrium density gradient ultracentrifugation. These results indicate that 1) apoA-V inefficiently traffics within the secretory pathway but that its intracellular itinerary may be regulated by changes in TG synthesis and/or accumulation and 2) part of the effect of apoA-V on TG metabolism could be exerted at the level of hepatic TG mobilization and secretion."],"dc:identifier.uri":["http://hdl.handle.net/10339/14862"],"dc:language.iso":["en_US"],"dc:publisher":["Wake Forest University"],"dc:subject":["Apolipoprotein"],"dc:title":["ROLE OF APOLIPOPROTEIN A-V IN TRIGLYCERIDE METABOLISM"],"dc:type":["Dissertation"]},"updated_at":"2026-07-27T22:01:07Z"}