Transcription factors and coactivators controlling nutrient and hormonal regulation of hepatic gluconeogenesis. 2012

Sarawut Jitrapakdee
Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand. scsji@mahidol.ac.th

Hepatic gluconeogenesis is a major pathway that maintains normal plasma glucose levels during prolonged starvation. The aim of this review is to provide insights into the integration of transcriptional regulation of gluconeogenic enzyme genes in response to nutritional and hormonal changes. The roles of transcription factors/co-regulators in response to those factors will be discussed. Overall, glucagon and glucocorticoids are positive regulators of gluconeogenesis. Glucagon, via cAMP, promotes the interaction of cAMP-responsive binding protein with CREB-regulated transcription coactivator 2 which facilitates its binding to cAMP-responsive elements (CREs). The response to glucocorticoids is mediated by the glucocorticoid receptor that binds to glucocorticoid responsive elements (GREs) in the promoters of gluconeogenic genes. These CREs and GREs may be arranged as distinct elements or combined to form a "unit" to ensure the maximal transcriptional response to these hormones. The hepatocyte nuclear factors, forkhead O box, and the peroxisome proliferator-activated receptor-γ coactivator 1α can also synergistically increase transcription of gluconeogenic genes. Surtuin 1, an energy sensor can also modify the transcriptional activity of some of these transcription factors. In contrast, insulin secreted during fed conditions acts to repress transcription of gluconeogenic enzymes. This is achieved via activation of Akt/PKB and the consequent disruption of interactions between certain transcription factors/coactivators and their positive response elements in the promoters of those genes. Hypothalamic signaling via the insulin/leptin axis also regulates hepatic gluconeogenesis. Mice lacking the above transcription factors/coactivators show impaired gluconeogenesis, indicating their essential roles in the control of this vital metabolic process.

UI MeSH Term Description Entries
D008099 Liver A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances. Livers
D008112 Liver Glycogen Glycogen stored in the liver. (Dorland, 28th ed) Hepatic Glycogen,Glycogen, Hepatic,Glycogen, Liver
D005786 Gene Expression Regulation Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation. Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
D005943 Gluconeogenesis Biosynthesis of GLUCOSE from nonhexose or non-carbohydrate precursors, such as LACTATE; PYRUVATE; ALANINE; and GLYCEROL.
D006728 Hormones Chemical substances having a specific regulatory effect on the activity of a certain organ or organs. The term was originally applied to substances secreted by various ENDOCRINE GLANDS and transported in the bloodstream to the target organs. It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects. Hormone,Hormone Receptor Agonists,Agonists, Hormone Receptor,Receptor Agonists, Hormone
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014157 Transcription Factors Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process. Transcription Factor,Factor, Transcription,Factors, Transcription
D015398 Signal Transduction The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway. Cell Signaling,Receptor-Mediated Signal Transduction,Signal Pathways,Receptor Mediated Signal Transduction,Signal Transduction Pathways,Signal Transduction Systems,Pathway, Signal,Pathway, Signal Transduction,Pathways, Signal,Pathways, Signal Transduction,Receptor-Mediated Signal Transductions,Signal Pathway,Signal Transduction Pathway,Signal Transduction System,Signal Transduction, Receptor-Mediated,Signal Transductions,Signal Transductions, Receptor-Mediated,System, Signal Transduction,Systems, Signal Transduction,Transduction, Signal,Transductions, Signal
D015533 Transcriptional Activation Processes that stimulate the GENETIC TRANSCRIPTION of a gene or set of genes. Gene Activation,Genetic Induction,Transactivation,Induction, Genetic,Trans-Activation, Genetic,Transcription Activation,Activation, Gene,Activation, Transcription,Activation, Transcriptional,Genetic Trans-Activation,Trans Activation, Genetic

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