Protein deprivation not only has immediate regulatory effects on gene expression, but can also have long-term effects through chromatin-associated mechanisms. However, there are significant gaps in our knowledge about the impact of dietary protein fluctuation on basic cell functions, including transcription. At the level of individual tissues/cells, dietary protein deficiency is reflected as amino acid (AA) limitation and therefore, AA deprivation of cultured cells is a useful model to investigate the genomic mechanisms of transcriptional control. Dietary protein limitation in vivo or AA deprivation in cell culture activates a multi-pathway AA response (AAR) that is one of several stress-activated signaling mechanisms that culminate in ATF4 synthesis. A microarray study identified members of the FOS/JUN family of transcription factors as AA-regulated genes in human HepG2 hepatocellular carcinoma (HCC) cells. Subsequent studies showed that cJUN regulates several downstream genes that are known AAR targets. Two additional novel observations were made. First, the induction of the cJUN gene is ATF4-independent, and therefore, must contain a novel AA response element (AARE), which may be linked to a novel signaling pathway. Second, the induction of cJUN occurs in human HCC cells, but not in primary human hepatocytes or in a non-transformed immortalized hepatocyte cell line. The proposed studies are innovative because: 1) they will provide the first investigation of a protein/AA responsive gene by an ATF4-independent mechanism, and 2) they will establish the mechanism for regulation of the cJUN gene in an animal tumor model in vivo, as well as in cultured human hepatoma cells and normal hepatocytes. Our global hypothesis is that the cJUN gene contains a novel AARE and is activated in HCC cells by an ATF4-independent signaling pathway, and that elevated cJUN expression supports continued HCC proliferation during dietary protein or AA limitation. The proposed experiments will test the following hypotheses: (Hypothesis I) The cJUN gene is the target of a novel ATF4-independent AA signaling pathway;(Hypothesis II) The cJUN gene exhibits novel AA-responsive transcriptional mechanisms;and (Hypothesis III) cJUN modulates AAR genes and cell proliferation during protein/AA limitation.

Public Health Relevance

Sufficient dietary protein/amino acid availability is an important factor in maintenance of health, especially during pregnancy, fetal/neonatal development, and in the progression of a wide range of diseases, including diabetes and cancer. Despite these important relationships, the influence of dietary protein/amino acid fluctuation on fundamental cellular processes and pathological states, such as the development and maintenance of tumors, are topics about which we know relatively little. The proposed research will investigate the mechanisms that lead the FOS/JUN family of proteins, major regulators of gene expression and cell proliferation, to be induced by amino acid limitation of human tumor cells, but not their normal counterparts.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK094729-04
Application #
8721948
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Maruvada, Padma
Project Start
2011-09-23
Project End
2015-08-31
Budget Start
2014-09-01
Budget End
2015-08-31
Support Year
4
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Florida
Department
Biochemistry
Type
Schools of Medicine
DUNS #
City
Gainesville
State
FL
Country
United States
Zip Code
32611
Yuniati, Laurensia; van der Meer, Laurens T; Tijchon, Esther et al. (2016) Tumor suppressor BTG1 promotes PRMT1-mediated ATF4 function in response to cellular stress. Oncotarget 7:3128-43
Shan, Jixiu; Donelan, William; Hayner, Jaclyn N et al. (2015) MAPK signaling triggers transcriptional induction of cFOS during amino acid limitation of HepG2 cells. Biochim Biophys Acta 1853:539-48
Guimarães-Camboa, Nuno; Stowe, Jennifer; Aneas, Ivy et al. (2015) HIF1α Represses Cell Stress Pathways to Allow Proliferation of Hypoxic Fetal Cardiomyocytes. Dev Cell 33:507-21
Palmer, Elizabeth Emma; Hayner, Jaclyn; Sachdev, Rani et al. (2015) Asparagine Synthetase Deficiency causes reduced proliferation of cells under conditions of limited asparagine. Mol Genet Metab 116:178-86
Crawford, Rebecca R; Prescott, Eugenia T; Sylvester, Charity F et al. (2015) Human CHAC1 Protein Degrades Glutathione, and mRNA Induction Is Regulated by the Transcription Factors ATF4 and ATF3 and a Bipartite ATF/CRE Regulatory Element. J Biol Chem 290:15878-91
Shan, Jixiu; Balasubramanian, Mukundh N; Donelan, William et al. (2014) A mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)-dependent transcriptional program controls activation of the early growth response 1 (EGR1) gene during amino acid limitation. J Biol Chem 289:24665-79
Fan, Alex Xiucheng; Papadopoulos, Giorgio L; Hossain, Mir A et al. (2014) Genomic and proteomic analysis of transcription factor TFII-I reveals insight into the response to cellular stress. Nucleic Acids Res 42:7625-41
Teske, Brian F; Fusakio, Michael E; Zhou, Donghui et al. (2013) CHOP induces activating transcription factor 5 (ATF5) to trigger apoptosis in response to perturbations in protein homeostasis. Mol Biol Cell 24:2477-90
Han, Jaeseok; Back, Sung Hoon; Hur, Junguk et al. (2013) ER-stress-induced transcriptional regulation increases protein synthesis leading to cell death. Nat Cell Biol 15:481-90
Fu, Lingchen; Kilberg, Michael S (2013) Elevated cJUN expression and an ATF/CRE site within the ATF3 promoter contribute to activation of ATF3 transcription by the amino acid response. Physiol Genomics 45:127-37

Showing the most recent 10 out of 15 publications