Progress 03/01/07 to 02/29/12
Outputs
OUTPUTS: "Besides designing, executing, analyzing and publishing experiments described in the outcomes/impacts section, the following outputs were generated. Diet-induced Obesity Decreases Liver Fe Stores in Mice Fed Iron Deficient, Adequate or Excessive Diets. Healy, B.J., Killilea D.W. and Hintze K.J. Experimental Biology. 2012. Transcritional and translational regulation of ferritin. K.J. Hintze. Children's Hospital of Oakland Research Institute. Elizabeth Theil: 55 Years of Research Symposium. 2011. Invited Talk Iron Metabolism and Obesity. K.J. Hintze. Utah State Hospital. 2011. Invited Talk." PARTICIPANTS: "Korry Hintze (Project leader) Robert Ward (Collaborator, USU) Heidi Wengreen (Collaborator, USU) James McClung (Collaborator, United States Army) David Killilea (Collaborator, Children's Hospital of Oakland) Elizabeth Theil (Collaborator, Children's Hospital of Oakland) Brett Healy (Graduate Student) Dallin Snow (Graduate Student) Darren Nabor (Undergraduate) Hunter Timbimboo (Undergraduate)" TARGET AUDIENCES: Local, State, International PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
"Besides designing, executing, analyzing and publishing experiments described in the outcomes/impacts section, the following outputs were generated. Diet-induced Obesity Decreases Liver Fe Stores in Mice Fed Iron Deficient, Adequate or Excessive Diets. Healy, B.J., Killilea D.W. and Hintze K.J. Experimental Biology. 2012. Transcritional and translational regulation of ferritin. K.J. Hintze. Children's Hospital of Oakland Research Institute. Elizabeth Theil: 55 Years of Research Symposium. 2011. Invited Talk Iron Metabolism and Obesity. K.J. Hintze. Utah State Hospital. 2011. Invited Talk."
Publications
- No publications reported this period
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Besides designing, executing, analyzing and publishing experiments described in the outcomes/impacts section, the following outputs were generated. Diet-induced Obesity Decreases Liver Fe Stores in Mice Fed Iron Deficient, Adequate or Excessive Diets. Healy, B.J., Killilea D.W. and Hintze K.J. Experimental Biology. 2012. Transcritional and translational regulation of ferritin. K.J. Hintze. Children's Hospital of Oakland Research Institute. Elizabeth Theil: 55 Years of Research Symposium. 2011. Invited Talk Iron Metabolism and Obesity. K.J. Hintze. Utah State Hospital. 2011. Invited Talk. PARTICIPANTS: Korry Hintze (Project leader), Robert Ward (Collaborator, USU), Heidi Wengreen (Collaborator, USU), James McClung (Collaborator, United States Army), David Killilea (Collaborator, Children's Hospital of Oakland), Elizabeth Theil (Collaborator, Children's Hospital of Oakland), Brett Healy (Graduate Student), Dallin Snow (Graduate Student), Darren Nabor (Undergraduate) and Hunter Timbimboo (Undergraduate). TARGET AUDIENCES: Local, State, International. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Iron is an absolute requirement for life; it is involved in several biochemical reactions ranging from cell respiration to DNA synthesis. The biology of iron is fraught with paradoxes; the same chemical properties that make iron essential can also catalyze the production of free radicals that have been implicated in the etiology of most chronic diseases that plague modern society. Diseases associated with iron toxicity such as hemochromatosis, sickle cell anemia and thalassemia are among the most common inherited diseases worldwide. Conversely, dietary iron deficiency is the most common mineral deficiency affecting an estimated 1.5 billion people worldwide. In the United States, 6.6% of reproductive aged women are iron deficient as well as 11% of children and adolescents. The link between slow cognitive development and iron deficiency makes the potential social and economic impact of iron deficiency great and stresses the need for understanding the mechanisms of iron metabolism and absorption from the diet. Exacerbating the iron deficiency epidemic is obesity. It has long been known that obesity is associated with poor iron status. Studies have demonstrated this association in children and adolescents, adult men and women, and postmenopausal women and as an independent factor contributing to iron deficiency. Obesity is becoming one of the most pressing health issues facing society. Obesity rates are increasing worldwide, the World Health Organization (WHO) estimated recently that, 1.6 billion adults were overweight; and at least 400 million adults were obese. The WHO projects that by 2015, approximately 2.3 billion adults will be overweight and more than 700 million will be obese. For the first time in human history, over-nutrition is emerging as larger problem than under-nutrition. Because a significant proportion of the worlds population is iron deficient, obese or both; it is absolutely critical to understand the mechanisms underlying obesity induced iron deficiency. Since the start of this project, I have completed several cellular iron metabolism studies. Some of the novel discoveries of this research include: i) First to demonstrate that ferritin is regulated by the heme-binding, transcription repressor bach1. ii) First to demonstrate thioredoxin reductase is regulated by bach1. iii) First to develop an in-vitro co-culture system to model obesity effects on iron metabolism. iv) First to show that adipocyte hypoxia increases hepcidin expression. v) First to demonstrate a hierarchy of hepatocyte hepcidin expression in response to iron availability or hypoxia. vi) First to show that obesity reduces liver iron stores independent of dietary iron intake . Based on data published thus far and my increasing visibility in the field, I am hopeful to obtain NIH funding for this line of research in the next year. The overall conclusion of these studies is that obesity increases chronic inflammation through adipocyte hypoxia. Inflammation in turn increases hepcidin production and decreases iron absorption and iron levels in the liver. These studies suggest that obese compared to lean people may be at greater risk for iron deficiency anemia.
Publications
- UTAO+262 Hintze, K. J., & McClung, J. P., (2011). Hepcidin: A Critical Regulator of Iron Metabolism during Hypoxia.: Advances in Hematology, 2011. (Published).
- UTAO+262 Hintze, K. J., Jeffery, E., Kong, T., Lei, X., & Finley, J., (2011). In vivo actions of antioxidants: new perspectives.: Journal of Agricultural and Food Chemistry, 59: 6837-46. (Published).
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Outputs for 2010 include the development of a cell culture model to emulate obesity as it relates to iron metabolism. This work resulted in the publication of a peer-reviewed manuscript as well as submission of another manuscript currently in review. Based on this work I was invited to give a talk this year at the National American Chemical Society Meeting and have also been invited to speak at the conference "Essentiality, Health Aspects and Toxicity of Trace Elements in Humans" that will be held on October 16-21, 2011 in Belek (Antalya), Turkey. This work was also the basis for an NIH R01 grant submission that was unfortunately not funded but is planned for re-submission in February of 2011. Milestones and deliverables for this year include 1) Cloning and characterization of the hepcidin promoter (completed and published). 2) Studies examining the effect of iron and hypoxia on hepcidin promoter activity (completed and published). 3) Development of co-culture models to model obesity in-vitro and examine effects on hepcidin expression and iron metabolism (completed and published). The final output of this project is development of diet-induced obesity/iron metabolism mouse model and is currently underway. PARTICIPANTS: Korry Hintze, Project Director; Brett Healy, Graduate Student TARGET AUDIENCES: Local, State, International PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Published work generated this year was the first to show that fat cell hypoxia (a hallmark of obesity) plays a role in increased hepcidin expression resulting in poor dietary iron absorption and provides a molecular link between obesity and poor iron status. This finding is important because it has long been known that obesity is linked to poor iron status regardless of dietary iron intake. However, the mechanisms of why this is the case have been elusive and work completed this year provides insight on why obesity decreases iron status.
Publications
- No publications reported this period
- Hintze, K. J., Snow, D., Nabor, D., Timbimboo, H. (2010). Adipocyte Hypoxia Increases Hepatocyte Hepcidin Expression. Biological Trace Element Research, online publication DOI 10.1007/s12011-010-8932-6.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Iron is an absolute requirement for life; it is involved in several biochemical reactions ranging from cell respiration to DNA synthesis. The biology of iron is fraught with paradoxes; diseases associated with iron toxicity are among the most common inherited diseases worldwide. Conversely, iron deficiency is the most common mineral deficiency affecting 1.5 billion people worldwide. The link between impaired cognition and iron deficiency makes the impact of iron deficiency great and stresses the need for understanding mechanisms of iron metabolism. Exacerbating the iron deficiency epidemic is obesity. Obesity is associated with poor iron status. Studies have demonstrated this in children, adolescents, adults and postmenopausal women and is an independent factor contributing to iron deficiency. Obesity is becoming one of the most pressing health issues facing society. Obesity rates are increasing worldwide, the World Health Organization estimates 1.6 billion adults are overweight; and 400 million adults are obese. Because a significant proportion of the worlds population is iron deficient, obese or both; it is absolutely critical to understand the mechanisms underlying obesity induced iron deficiency. Because of the dual nature of iron, uptake and partitioning is exquisitely regulated. Perhaps the most significant recent breakthrough in dietary iron regulation was the discovery of the hormone hepcidin. Hepcidin plays a key role in regulating organismal iron metabolism. Increases in hepcidin expression deplete serum iron levels, prevents iron efflux from enterocytes and macrophages. Hepcidin targets and degrades the cellular iron exporter ferroportin, thus preventing iron efflux from hepatocytes, macrophages and enterocytes dropping systemic iron levels. Hepcidin expression is increased by iron overload and inflammation and decreased by hypoxia. Thus, hepcidin is the iron/inflammation/oxygen sensor that signals the mucosal block phenomenon, anemia of infection and increased iron uptake during hypoxia. Interleukin-6 (IL-6) appears to play a key role in increasing hepcidin expression in response to inflammation. Chronic inflammation is one of the hallmarks of obesity. Recently it was shown that adipose tissue in obese mice is more hypoxic than adipose tissue from lean mice. This difference in O2 tension results in increased gene expression in expected genes such as VEGF and heme-oxygenase, but also inflammatory cytokines TNF-a IL-1 and IL-6. Increased expression of cytokines was also demonstrated in adipocytes cultured under hypoxic conditions (1% O2) suggesting that this system is an ideal model to study the effects of hypoxia on adipocyte cytokine gene expression. Therefore, the overall objective is to investigate the links between obesity induced inflammation, hepcidin expression and iron status. Obesity will be modeled in-vitro using conditioned media from hypoxic adipocytes. Adipocyte hypoxia is known to mediate the inflammatory signature of central obesity. This model will be used to assess: hepatocyte hepcidin expression, hepcidin promoter construct activity with or without key regulatory mutations. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Local, State, International PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The hepcidin promoter has been successfully cloned into a luciferase reporter construct. Studies have been completed examining the effects of differing dietary forms of iron and/or hypoxia on hepcidin expression. Furthermore, using the same experimental conditions, results have been verified using quantitative PCR. A cell culture model using culture media from hypoxic adipocytes on hepcidin expressing hepatocytes has been developed. Utilizing this model I have demonstrated that hypoxic 3T3-L1 adipocytes secrete increased amounts of IL-6 and signal hepcidin expression in hepatocytes. I have also shown through hepcidin promoter mutation analysis that increased hepatocyte hepcidin expression via hypoxic adipocytes is dependent on the STAT3 binding site in the hepcidin promoter.
Publications
- Nemere I., Hintze, K. 2008. Novel hormone receptors. Journal of Cellular Biochemistry 103:401-7.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: In the United States, estimates of iron deficiency in women of reproductive age are 6.6% and for children and adolescents, 11%. This translates to ~54% of Utahns at risk with ~5% iron deficiency. Perhaps the most significant recent breakthrough in dietary iron regulation was the discovery of the peptide hormone hepcidin. Hepcidin is synthesized in the liver in response to infection or excess iron and expression is decreased by anemia and hypoxia. It appears that hepcidin is the key signal for decreasing plasma iron as a host defense mechanism by limiting iron for pathogens as well as limiting iron efflux from enterocytes in response to iron overload. Currently, cell culture models of iron absorption lack hepcidin feedback. Essentially, these models mimic some types of the iron overload disease hemochromatosis that are characterized by hepcidin deficiency leading to a disconnect between liver iron stores and intestinal iron absorption. In normal iron absorption, hepcidin is essential to the "mucosal block" phenomenon wherein iron absorption is curtailed after dietary iron overload. Existing cell models of iron absorption consider only one side of the equation and not physiologically relevant to whole organism iron metabolism. Therefore, Objective 1) is to develop a cell culture model of dietary iron absorption that incorporates hepcidin feedback using Caco2 enterocytes and conditioned media from hepcidin expressing Huh7 cells. Objective 2) To determine how iron and hypoxia signal hepcidin expression, the promoter of the human hepcidin gene will be cloned into a luciferase reporter construct. Despite the fact that heme-iron is the most abundant dietary iron source, much less is kown about its transport into enterocytes than inorganic iron. Recently, a heme carrier protein (HCP1) was identified in mouse duodenum. HCP1 expression is responsive to hypoxia and to a lesser extent, iron status. The mechanisms of how HCP1 is regulated by iron or hypoxia are not currently known. It is likely that HCP1 is regulated by promoter/transcription factor interactions that are sensitive to iron and/or hypoxia. The third objective To test the hypothesis that hypoxia and heme regulation of the HCP1 gene is mediated through the gene promoter; the HCP1 promoter will be cloned (-3000 to the transcription start site) into a luciferase reporter construct. A series of 10 nested deletion constructs (300 bp) will also be generated for promoter characterization. To determine regulatory regions of the HCP1 promoter, deletion constructs will be transfected into a duodenal cell line (HT29) and cells will be exposed to: hypoxia (1% O2) or heme (80 uM). Studies have been completed or are underway examining the effects of differing dietary forms of iron and/or hypoxia on hepcidin expression. Furthermore, using the same experimental conditions, results have been verified using quantitative PCR. Data obtained thus far has been submitted in abstract form to be presented at Experimental Biology 2009. This data will be used for an NIH grant submission and a manuscript currently in development. PARTICIPANTS: Collaborations Dr William Self, University of Central Florida : Trivalent Arsenicals and Thioredoxin Reductase Expression. Dr Robert Ward and Dr Ilka Nemere, Utah State University: Inhibitory effect of milk fat fractions on the occurrence of dimethylhydrazine induced Aberrant Crypt Foci in rats. Associate Member, Center For Advanced Nutrition TARGET AUDIENCES: Local, State, International PROJECT MODIFICATIONS: Recent literature has questioned the validity of whether the heme carrier protein (HCP1) is the true intestinal heme transporter. After consulting with colleagues in the field, Objective 3 (To test the hypothesis that hypoxia and heme regulation of the HCP1 gene is mediated through the gene promoter) has been discontinued. Objective 2 has been expanded to examine the effects of hypoxia induced adipocyte inflammation on hepcidin expression. It has been known for several years that obesity leads to decreased iron absorption but the mechanism remains unclear. Adipocyte hypoxia, a hallmark of obesity, increases expression of inflammatory cytokines. Experiments conducted over the last year in my lab have confirmed that hepatocyte hepcidin expression is increased when exposed to media from hypoxic adipocytes. This data suggests a possible mechanism for obesity induced anemia and is currently being pursued.
Impacts
In the last year most progress has been made on objective 2 (To determine how iron and hypoxia signal hepcidin expression), the promoter of the human hepcidin gene will be cloned into a luciferase reporter construct. The hepcidin promoter has been successfully cloned into a luciferase reporter construct. Moreover, emerging data suggests that obesity induced inflammation by hypoxic adipocytes may influence hepcidin expression. Therefore a cell culture model using culture media from hypoxic adipocytes on hepcidin expressing hepatocytes has been developed.
Publications
- Meno SR, Nelson R, Hintze KJ, Self WT. 2008. Exposure to monomethylarsonous acid (MMA(III)) leads to altered selenoprotein synthesis in a primary human lung cell model. Toxicol Appl Pharmacol. :In Press.
- Nabor, D Hintze, K.J 2008. Effects of Sulforaphane on IMR-90 Phase II Enzyme Induction and Cell Senescence.. FASEB Journal 22:700.29.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Research: Converted derelict lab space into a functioning molecular biology lab. Established cell culture facility in the Nutrition & Food Sciences Department. Ongoing Research Cloning and Characterization of the Heme Carrier Protein Promoter Hepcidin Regulation by Iron and Oxygen Effect of Phase II Enzymes on the IMR-90 Aging Cell Model Inhibitory effect of milk fat fractions on the occurrence of dimethylhydrazine induced Aberrant Crypt Foci in rats Effect of AP2 Knockout on the Aberrant Crypt Foci Colon Cancer Model. Effect of Hypoxia on Phase II Enzyme Regulation Presentations: Invited presentation: Selenium and Human Health. USANA Corporation, Salt Lake City, UT.
PARTICIPANTS: Collaborations Dr William Self, University of Central Florida : Trivalent Arsenicals and Thioredoxin Reductase Expression. Dr David Killilea, Children's Hospital of Oakland Research Institute: Effect of Phase II Enzyme Inducers on the IMR-90 Aging Cell Model. Dr Robert Ward and Dr Ilka Nemere, Utah State University: Inhibitory effect of milk fat fractions on the occurrence of dimethylhydrazine induced Aberrant Crypt Foci in rats. Dr Quinton Winger, Utah State University: Effect of AP2 Knockout on the Aberrant Crypt Foci Colon Cancer Model. Associate Member, Center For Advanced Nutrition.
TARGET AUDIENCES: Local, State, International
Impacts
It is estimated that 1 billion suffer from iron deficiency and is the most common nutrient deficiency worldwide. Conversely, the iron overload disease hemochromatosis is the most common genetic disease among people of European descent. Therefore, it is crucial to understand the molecular mechanisms that relate to dietary iron absorption and transport. Ongoing work from my laboratory is focused on the molecular events involved with iron regulation. This work will increase our understanding of how dietary iron is regulated and will help in devising strategies to combat both iron deficiency and overload.
Publications
- Hintze KJ, Katoh Y, Igarashi K, Theil EC. 2007. Bach1 Repression of Ferritin and Thioredoxin Reductase1 Is Heme-sensitive in Cells and in Vitro and Coordinates Expression with Heme Oxygenase1, beta-Globin, and NADP(H) Quinone (Oxido) Reductase1.. Journal of Biological Chemistry 282:34365.
- Nemere I., Hintze, K. 2007. Novel hormone receptors. Journal of Cellular Biochemistry (in press).
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