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Kajani S, Laker RC, Ratkova E, Will S, Rhodes CJ. Hepatic glucagon action: beyond glucose mobilization. Physiol Rev 2024; 104:1021-1060. [PMID: 38300523 DOI: 10.1152/physrev.00028.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 02/02/2024] Open
Abstract
Glucagon's ability to promote hepatic glucose production has been known for over a century, with initial observations touting this hormone as a diabetogenic agent. However, glucagon receptor agonism [when balanced with an incretin, including glucagon-like peptide 1 (GLP-1) to dampen glucose excursions] is now being developed as a promising therapeutic target in the treatment of metabolic diseases, like metabolic dysfunction-associated steatotic disease/metabolic dysfunction-associated steatohepatitis (MASLD/MASH), and may also have benefit for obesity and chronic kidney disease. Conventionally regarded as the opposing tag-team partner of the anabolic mediator insulin, glucagon is gradually emerging as more than just a "catabolic hormone." Glucagon action on glucose homeostasis within the liver has been well characterized. However, growing evidence, in part thanks to new and sensitive "omics" technologies, has implicated glucagon as more than just a "glucose liberator." Elucidation of glucagon's capacity to increase fatty acid oxidation while attenuating endogenous lipid synthesis speaks to the dichotomous nature of the hormone. Furthermore, glucagon action is not limited to just glucose homeostasis and lipid metabolism, as traditionally reported. Glucagon plays key regulatory roles in hepatic amino acid and ketone body metabolism, as well as mitochondrial turnover and function, indicating broader glucagon signaling consequences for metabolic homeostasis mediated by the liver. Here we examine the broadening role of glucagon signaling within the hepatocyte and question the current dogma, to appreciate glucagon as more than just that "catabolic hormone."
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Affiliation(s)
- Sarina Kajani
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, Maryland, United States
| | - Rhianna C Laker
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, Maryland, United States
| | - Ekaterina Ratkova
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Mölndal, Sweden
| | - Sarah Will
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, Maryland, United States
| | - Christopher J Rhodes
- Early Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gaithersburg, Maryland, United States
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2
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Tan VWT, Salmi TM, Karamalakis AP, Gillespie A, Ong AJS, Balic JJ, Chan YC, Bladen CE, Brown KK, Dawson MA, Cox AG. SLAM-ITseq identifies that Nrf2 induces liver regeneration through the pentose phosphate pathway. Dev Cell 2024; 59:898-910.e6. [PMID: 38366599 DOI: 10.1016/j.devcel.2024.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 12/07/2023] [Accepted: 01/24/2024] [Indexed: 02/18/2024]
Abstract
The liver exhibits a remarkable capacity to regenerate following injury. Despite this unique attribute, toxic injury is a leading cause of liver failure. The temporal processes by which the liver senses injury and initiates regeneration remain unclear. Here, we developed a transgenic zebrafish model wherein hepatocyte-specific expression of uracil phosphoribosyltransferase (UPRT) enabled the implementation of SLAM-ITseq to investigate the nascent transcriptome during initiation of liver injury and regeneration. Using this approach, we identified a rapid metabolic transition from the fed to the fasted state that was followed by induction of the nuclear erythroid 2-related factor (Nrf2) antioxidant program. We find that activation of Nrf2 in hepatocytes is required to induce the pentose phosphate pathway (PPP) and improve survival following liver injury. Mechanistically, we demonstrate that inhibition of the PPP disrupts nucleotide biosynthesis to prevent liver regeneration. Together, these studies provide fundamental insights into the mechanism by which early metabolic adaptation to injury facilitates tissue regeneration.
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Affiliation(s)
- Vicky W T Tan
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Talhah M Salmi
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Anthony P Karamalakis
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Andrea Gillespie
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia
| | - Athena Jessica S Ong
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Jesse J Balic
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Yih-Chih Chan
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Cerys E Bladen
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Kristin K Brown
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia; Department of Biochemistry and Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Mark A Dawson
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia; Department of Clinical Haematology, Peter MacCallum Cancer Centre & Royal Melbourne Hospital, Melbourne, VIC 3000, Australia; Centre for Cancer Research, The University of Melbourne, Melbourne, VIC 3000, Australia.
| | - Andrew G Cox
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia; Department of Biochemistry and Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia.
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3
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Sen D, Maniyadath B, Chowdhury S, Kaur A, Khatri S, Chakraborty A, Mehendale N, Nadagouda S, Sandra U, Kamat SS, Kolthur-Seetharam U. Metabolic regulation of CTCF expression and chromatin association dictates starvation response in mice and flies. iScience 2023; 26:107128. [PMID: 37416476 PMCID: PMC10320512 DOI: 10.1016/j.isci.2023.107128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 05/16/2023] [Accepted: 06/10/2023] [Indexed: 07/08/2023] Open
Abstract
Coordinated temporal control of gene expression is essential for physiological homeostasis, especially during metabolic transitions. However, the interplay between chromatin architectural proteins and metabolism in regulating transcription is less understood. Here, we demonstrate a conserved bidirectional interplay between CTCF (CCCTC-binding factor) expression/function and metabolic inputs during feed-fast cycles. Our results indicate that its loci-specific functional diversity is associated with physiological plasticity in mouse hepatocytes. CTCF differential expression and long non-coding RNA-Jpx mediated changes in chromatin occupancy, unraveled its paradoxical yet tuneable functions, which are governed by metabolic inputs. We illustrate the key role of CTCF in controlling temporal cascade of transcriptional response, with effects on hepatic mitochondrial energetics and lipidome. Underscoring the evolutionary conservation of CTCF-dependent metabolic homeostasis, CTCF knockdown in flies abrogated starvation resistance. In summary, we demonstrate the interplay between CTCF and metabolic inputs that highlights the coupled plasticity of physiological responses and chromatin function.
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Affiliation(s)
- Devashish Sen
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Babukrishna Maniyadath
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Shreyam Chowdhury
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Arshdeep Kaur
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Subhash Khatri
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Arnab Chakraborty
- Department of Biology, Indian Institute of Science Education and Research, Pune, Maharashtra 411008, India
| | - Neelay Mehendale
- Department of Biology, Indian Institute of Science Education and Research, Pune, Maharashtra 411008, India
| | - Snigdha Nadagouda
- Tata Institute of Fundamental Research- Hyderabad (TIFR-H), Hyderabad, Telangana 500046, India
| | - U.S. Sandra
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Siddhesh S. Kamat
- Department of Biology, Indian Institute of Science Education and Research, Pune, Maharashtra 411008, India
| | - Ullas Kolthur-Seetharam
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
- Tata Institute of Fundamental Research- Hyderabad (TIFR-H), Hyderabad, Telangana 500046, India
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4
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Emerging Role of SMILE in Liver Metabolism. Int J Mol Sci 2023; 24:ijms24032907. [PMID: 36769229 PMCID: PMC9917820 DOI: 10.3390/ijms24032907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/29/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023] Open
Abstract
Small heterodimer partner-interacting leucine zipper (SMILE) is a member of the CREB/ATF family of basic leucine zipper (bZIP) transcription factors. SMILE has two isoforms, a small and long isoform, resulting from alternative usage of the initiation codon. Interestingly, although SMILE can homodimerize similar to other bZIP proteins, it cannot bind to DNA. As a result, SMILE acts as a co-repressor in nuclear receptor signaling and other transcription factors through its DNA binding inhibition, coactivator competition, and direct repression, thereby regulating the expression of target genes. Therefore, the knockdown of SMILE increases the transactivation of transcription factors. Recent findings suggest that SMILE is an important regulator of metabolic signals and pathways by causing changes in glucose, lipid, and iron metabolism in the liver. The regulation of SMILE plays an important role in pathological conditions such as hepatitis, diabetes, fatty liver disease, and controlling the energy metabolism in the liver. This review focuses on the role of SMILE and its repressive actions on the transcriptional activity of nuclear receptors and bZIP transcription factors and its effects on liver metabolism. Understanding the importance of SMILE in liver metabolism and signaling pathways paves the way to utilize SMILE as a target in treating liver diseases.
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5
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Sadasivam N, Radhakrishnan K, Choi HS, Kim DK. Emerging Role of SMILE in Liver Metabolism. Int J Mol Sci 2023; 24:2907. [DOI: https:/doi.org/10.3390/ijms24032907 academic] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/18/2023] Open
Abstract
Small heterodimer partner-interacting leucine zipper (SMILE) is a member of the CREB/ATF family of basic leucine zipper (bZIP) transcription factors. SMILE has two isoforms, a small and long isoform, resulting from alternative usage of the initiation codon. Interestingly, although SMILE can homodimerize similar to other bZIP proteins, it cannot bind to DNA. As a result, SMILE acts as a co-repressor in nuclear receptor signaling and other transcription factors through its DNA binding inhibition, coactivator competition, and direct repression, thereby regulating the expression of target genes. Therefore, the knockdown of SMILE increases the transactivation of transcription factors. Recent findings suggest that SMILE is an important regulator of metabolic signals and pathways by causing changes in glucose, lipid, and iron metabolism in the liver. The regulation of SMILE plays an important role in pathological conditions such as hepatitis, diabetes, fatty liver disease, and controlling the energy metabolism in the liver. This review focuses on the role of SMILE and its repressive actions on the transcriptional activity of nuclear receptors and bZIP transcription factors and its effects on liver metabolism. Understanding the importance of SMILE in liver metabolism and signaling pathways paves the way to utilize SMILE as a target in treating liver diseases.
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Affiliation(s)
- Nanthini Sadasivam
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Kamalakannan Radhakrishnan
- Clinical Vaccine R&D Centre, Department of Microbiology, Combinatorial Tumour Immunotheraphy MRC, Medical School, Chonnam National University, Gwangju 58128, Republic of Korea
| | - Hueng-Sik Choi
- School of Biological Sciences and Technology, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Don-Kyu Kim
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, Republic of Korea
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6
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Kapadia B, Behera S, Kumar ST, Shah T, Edwin RK, Babu PP, Chakrabarti P, Parsa KV, Misra P. PIMT regulates hepatic gluconeogenesis in mice. iScience 2023; 26:106120. [PMID: 36866247 PMCID: PMC9972567 DOI: 10.1016/j.isci.2023.106120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/29/2022] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
The physiological and metabolic functions of PIMT/TGS1, a third-generation transcriptional apparatus protein, in glucose homeostasis sustenance are unclear. Here, we observed that the expression of PIMT was upregulated in the livers of short-term fasted and obese mice. Lentiviruses expressing Tgs1-specific shRNA or cDNA were injected into wild-type mice. Gene expression, hepatic glucose output, glucose tolerance, and insulin sensitivity were evaluated in mice and primary hepatocytes. Genetic modulation of PIMT exerted a direct positive impact on the gluconeogenic gene expression program and hepatic glucose output. Molecular studies utilizing cultured cells, in vivo models, genetic manipulation, and PKA pharmacological inhibition establish that PKA regulates PIMT at post-transcriptional/translational and post-translational levels. PKA enhanced 3'UTR-mediated translation of TGS1 mRNA and phosphorylated PIMT at Ser656, increasing Ep300-mediated gluconeogenic transcriptional activity. The PKA-PIMT-Ep300 signaling module and associated PIMT regulation may serve as a key driver of gluconeogenesis, positioning PIMT as a critical hepatic glucose sensor.
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Affiliation(s)
- Bandish Kapadia
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India
| | - Soma Behera
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India
| | - Sireesh T. Kumar
- Department of Biotechnology, University of Hyderabad, Hyderabad 500046, India
| | - Tapan Shah
- Department of Biochemistry, Saurashtra University, Rajkot 360005, India
| | - Rebecca Kristina Edwin
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India
| | | | | | - Kishore V.L. Parsa
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India,Corresponding author
| | - Parimal Misra
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India,Corresponding author
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7
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AMPK inhibits liver gluconeogenesis: fact or fiction? Biochem J 2023; 480:105-125. [PMID: 36637190 DOI: 10.1042/bcj20220582] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/21/2022] [Accepted: 01/04/2023] [Indexed: 01/14/2023]
Abstract
Is there a role for AMPK in the control of hepatic gluconeogenesis and could targeting AMPK in liver be a viable strategy for treating type 2 diabetes? These are frequently asked questions this review tries to answer. After describing properties of AMPK and different small-molecule AMPK activators, we briefly review the various mechanisms for controlling hepatic glucose production, mainly via gluconeogenesis. The different experimental and genetic models that have been used to draw conclusions about the role of AMPK in the control of liver gluconeogenesis are critically discussed. The effects of several anti-diabetic drugs, particularly metformin, on hepatic gluconeogenesis are also considered. We conclude that the main effect of AMPK activation pertinent to the control of hepatic gluconeogenesis is to antagonize glucagon signalling in the short-term and, in the long-term, to improve insulin sensitivity by reducing hepatic lipid content.
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8
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Acevedo‐Acevedo S, Stefkovich ML, Kang SWS, Cunningham RP, Cultraro CM, Porat‐Shliom N. LKB1 acts as a critical brake for the glucagon-mediated fasting response. Hepatol Commun 2022; 6:1949-1961. [PMID: 35357082 PMCID: PMC9315124 DOI: 10.1002/hep4.1942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/23/2022] [Accepted: 03/06/2022] [Indexed: 11/08/2022] Open
Abstract
As important as the fasting response is for survival, an inability to shut it down once nutrients become available can lead to exacerbated disease and severe wasting. The liver is central to transitions between feeding and fasting states, with glucagon being a key initiator of the hepatic fasting response. However, the precise mechanisms controlling fasting are not well defined. One potential mediator of these transitions is liver kinase B1 (LKB1), given its role in nutrient sensing. Here, we show LKB1 knockout mice have a severe wasting and prolonged fasting phenotype despite increased food intake. By applying RNA sequencing and intravital microscopy, we show that loss of LKB1 leads to a dramatic reprogramming of the hepatic lobule through robust up-regulation of periportal genes and functions. This is likely mediated through the opposing effect that LKB1 has on glucagon pathways and gene expression. Conclusion: Our findings show that LKB1 acts as a brake to the glucagon-mediated fasting response, resulting in "periportalization" of the hepatic lobule and whole-body metabolic inefficiency. These findings reveal a mechanism by which hepatic metabolic compartmentalization is regulated by nutrient-sensing.
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Affiliation(s)
- Suehelay Acevedo‐Acevedo
- Thoracic and GI Malignancies BranchCenter for Cancer ResearchNational Cancer Institute, NIHBethesdaMarylandUSA
| | - Megan L. Stefkovich
- Thoracic and GI Malignancies BranchCenter for Cancer ResearchNational Cancer Institute, NIHBethesdaMarylandUSA
| | - Sun Woo Sophie Kang
- Thoracic and GI Malignancies BranchCenter for Cancer ResearchNational Cancer Institute, NIHBethesdaMarylandUSA
| | - Rory P. Cunningham
- Thoracic and GI Malignancies BranchCenter for Cancer ResearchNational Cancer Institute, NIHBethesdaMarylandUSA
| | - Constance M. Cultraro
- Thoracic and GI Malignancies BranchCenter for Cancer ResearchNational Cancer Institute, NIHBethesdaMarylandUSA
| | - Natalie Porat‐Shliom
- Thoracic and GI Malignancies BranchCenter for Cancer ResearchNational Cancer Institute, NIHBethesdaMarylandUSA
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9
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Rodgers RL. Glucagon, cyclic AMP, and hepatic glucose mobilization: A half‐century of uncertainty. Physiol Rep 2022; 10:e15263. [PMID: 35569125 PMCID: PMC9107925 DOI: 10.14814/phy2.15263] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 12/14/2022] Open
Abstract
For at least 50 years, the prevailing view has been that the adenylate cyclase (AC)/cyclic AMP (cAMP)/protein kinase A pathway is the predominant signal mediating the hepatic glucose‐mobilizing actions of glucagon. A wealth of evidence, however, supports the alternative, that the operative signal most of the time is the phospholipase C (PLC)/inositol‐phosphate (IP3)/calcium/calmodulin pathway. The evidence can be summarized as follows: (1) The consensus threshold glucagon concentration for activating AC ex vivo is 100 pM, but the statistical hepatic portal plasma glucagon concentration range, measured by RIA, is between 28 and 60 pM; (2) Within that physiological concentration range, glucagon stimulates the PLC/IP3 pathway and robustly increases glucose output without affecting the AC/cAMP pathway; (3) Activation of a latent, amplified AC/cAMP pathway at concentrations below 60 pM is very unlikely; and (4) Activation of the PLC/IP3 pathway at physiological concentrations produces intracellular effects that are similar to those produced by activation of the AC/cAMP pathway at concentrations above 100 pM, including elevated intracellular calcium and altered activities and expressions of key enzymes involved in glycogenolysis, gluconeogenesis, and glycogen synthesis. Under metabolically stressful conditions, as in the early neonate or exercising adult, plasma glucagon concentrations often exceed 100 pM, recruiting the AC/cAMP pathway and enhancing the activation of PLC/IP3 pathway to boost glucose output, adaptively meeting the elevated systemic glucose demand. Whether the AC/cAMP pathway is consistently activated in starvation or diabetes is not clear. Because the importance of glucagon in the pathogenesis of diabetes is becoming increasingly evident, it is even more urgent now to resolve lingering uncertainties and definitively establish glucagon’s true mechanism of glycemia regulation in health and disease.
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Affiliation(s)
- Robert L. Rodgers
- Department of Biomedical and Pharmaceutical Sciences College of Pharmacy University of Rhode Island Kingston Rhode Island USA
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10
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Goldberg D, Charni-Natan M, Buchshtab N, Bar-Shimon M, Goldstein I. Hormone-controlled cooperative binding of transcription factors drives synergistic induction of fasting-regulated genes. Nucleic Acids Res 2022; 50:5528-5544. [PMID: 35556130 PMCID: PMC9177981 DOI: 10.1093/nar/gkac358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 04/22/2022] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
During fasting, hepatocytes produce glucose in response to hormonal signals. Glucagon and glucocorticoids are principal fasting hormones that cooperate in regulating glucose production via gluconeogenesis. However, how these hormone signals are integrated and interpreted to a biological output is unknown. Here, we use genome-wide profiling of gene expression, enhancer dynamics and transcription factor (TF) binding in primary mouse hepatocytes to uncover the mode of cooperation between glucagon and glucocorticoids. We found that compared to a single treatment with each hormone, a dual treatment directs hepatocytes to a pro-gluconeogenic gene program by synergistically inducing gluconeogenic genes. The cooperative mechanism driving synergistic gene expression is based on ‘assisted loading’ whereby a glucagon-activated TF (cAMP responsive element binding protein; CREB) leads to enhancer activation which facilitates binding of the glucocorticoid receptor (GR) upon glucocorticoid stimulation. Glucagon does not only activate single enhancers but also activates enhancer clusters, thereby assisting the loading of GR also across enhancer units within the cluster. In summary, we show that cells integrate extracellular signals by an enhancer-specific mechanism: one hormone-activated TF activates enhancers, thereby assisting the loading of a TF stimulated by a second hormone, leading to synergistic gene induction and a tailored transcriptional response to fasting.
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Affiliation(s)
- Dana Goldberg
- Institute of Biochemistry, Food Science and Nutrition. The Robert H. Smith Faculty of Agriculture, Food and Environment. The Hebrew University of Jerusalem. POB 12, Rehovot 7610001, Israel
| | - Meital Charni-Natan
- Institute of Biochemistry, Food Science and Nutrition. The Robert H. Smith Faculty of Agriculture, Food and Environment. The Hebrew University of Jerusalem. POB 12, Rehovot 7610001, Israel
| | - Nufar Buchshtab
- Institute of Biochemistry, Food Science and Nutrition. The Robert H. Smith Faculty of Agriculture, Food and Environment. The Hebrew University of Jerusalem. POB 12, Rehovot 7610001, Israel
| | - Meirav Bar-Shimon
- Institute of Biochemistry, Food Science and Nutrition. The Robert H. Smith Faculty of Agriculture, Food and Environment. The Hebrew University of Jerusalem. POB 12, Rehovot 7610001, Israel
| | - Ido Goldstein
- Institute of Biochemistry, Food Science and Nutrition. The Robert H. Smith Faculty of Agriculture, Food and Environment. The Hebrew University of Jerusalem. POB 12, Rehovot 7610001, Israel
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11
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Varticovski L, Stavreva DA, McGowan A, Raziuddin R, Hager GL. Endocrine disruptors of sex hormone activities. Mol Cell Endocrinol 2022; 539:111415. [PMID: 34339825 PMCID: PMC8762672 DOI: 10.1016/j.mce.2021.111415] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 12/20/2022]
Abstract
Sex hormones, such as androgens, estrogens and progestins are naturally occurring compounds that tightly regulate endocrine systems in a variety of living organisms. Uncontrolled environmental exposure to these hormones or their biological and synthetic mimetics has been widely documented. Furthermore, water contaminants penetrate soil to affect flora, fauna and ultimately humans. Because endocrine systems evolved to respond to very small changes in hormone levels, the low levels found in the environment cannot be ignored. The combined actions of sex hormones with glucocorticoids and other nuclear receptors disruptors creates additional level of complexity including the newly described "dynamic assisted loading" mechanism. We reviewed the extensive literature pertaining to world-wide detection of these disruptors and created a detailed Table on the development and current status of methods used for their analysis.
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Affiliation(s)
- L Varticovski
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - D A Stavreva
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - A McGowan
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - R Raziuddin
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - G L Hager
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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12
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Zhou X, Yan Q, Yang H, Ren A, He Z, Tan Z. Maternal intake restriction programs the energy metabolism, clock circadian regulator and mTOR signals in the skeletal muscles of goat offspring probably via the protein kinase A-cAMP-responsive element-binding proteins pathway. ANIMAL NUTRITION (ZHONGGUO XU MU SHOU YI XUE HUI) 2021; 7:1303-1314. [PMID: 34786503 PMCID: PMC8567324 DOI: 10.1016/j.aninu.2021.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 08/25/2021] [Accepted: 09/08/2021] [Indexed: 01/25/2023]
Abstract
The biological mechanism by which maternal undernutrition increases the metabolic disorder risk of skeletal muscles in offspring is not fully understood. We hypothesize that maternal intake restriction influences metabolic signals in the skeletal muscles of offspring via a glucagon-mediated pathway. Twenty-four pregnant goats were assigned to the control group (100% of the nutrients requirement, n = 12) and restricted group (60% of the control feed allowance from pregnant days 45 to 100, n = 12). Blood and L ongissimus thoracis muscle were sampled from dams (100 d of gestation), fetuses (100 d of gestation), and kids (90 d after birth) in each group. The data were analyzed using the linear MIXED model, with the multiple comparison method of SIDAK applied. Intake restriction reduced (P < 0.05) the total blood protein of dams and fetuses. Maternal restriction decreased (P < 0.05) the cAMP-responsive element-binding protein 1 (CREB1), CREB-binding protein (CREBBP), protein kinase A (PKA), aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1), protein kinase B (AKT1), mammalian target of rapamycin (mTOR), and regulatory-associated protein of mTOR (RPTOR) mRNA expression in the fetuses, and reduced (P < 0.05) the CREBBP, nuclear receptor subfamily 1 group H member 3 (NR1H3), D-box binding PAR bZIP transcription factor (DBP) and PKA mRNA levels in the kids, but increased (P < 0.05) the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1 A) and tuberous sclerosis 2 (TSC2) mRNA levels in the fetuses. The mRNA expression of clock circadian regulator (CLOCK) and TSC2 genes was increased (P < 0.05) in the restricted kids. The protein expression of total PKA and phosphorylated PKA in the restricted fetuses and kids were downregulated (P < 0.05), and the protein expression of total mTOR and phosphorylated mTOR were reduced (P < 0.05) in the restricted fetuses and kids. Maternal intake restriction regulated fat oxidation, protein synthesis, and circadian clock expression in the muscles of the offspring probably via the glucagon-mediated PKA-CREB pathway, which reveals a noteworthy molecular pathway that maternal undernutrition leads to metabolic adaptation of skeletal muscle in offspring.
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Affiliation(s)
- Xiaoling Zhou
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China
- University of the Chinese Academy of Science, Beijing, 100049, China
- College of Animal Science, Tarim University, Alaer, 843300, China
| | - Qiongxian Yan
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China
- Hunan Co-Innovation Center for Utilization of Botanical Functional Ingredients, Changsha, 410128, China
| | - Hong Yang
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China
| | - Ao Ren
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China
| | - Zhixiong He
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China
| | - Zhiliang Tan
- CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, South-Central Experimental Station of Animal Nutrition and Feed Science in Ministry of Agriculture, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China
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13
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Korenfeld N, Finkel M, Buchshtab N, Bar-Shimon M, Charni-Natan M, Goldstein I. Fasting Hormones Synergistically Induce Amino Acid Catabolism Genes to Promote Gluconeogenesis. Cell Mol Gastroenterol Hepatol 2021; 12:1021-1036. [PMID: 33957303 PMCID: PMC8346669 DOI: 10.1016/j.jcmgh.2021.04.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/27/2021] [Accepted: 04/27/2021] [Indexed: 12/10/2022]
Abstract
BACKGROUND & AIMS Gluconeogenesis from amino acids (AAs) maintains glucose homeostasis during fasting. Although glucagon is known to regulate AA catabolism, the contribution of other hormones to it and the scope of transcriptional regulation dictating AA catabolism are unknown. We explored the role of the fasting hormones glucagon and glucocorticoids in transcriptional regulation of AA catabolism genes and AA-dependent gluconeogenesis. METHODS We tested the RNA expression of AA catabolism genes and glucose production in primary mouse hepatocytes treated with fasting hormones (glucagon, corticosterone) and feeding hormones (insulin, fibroblast growth factor 19). We analyzed genomic data of chromatin accessibility and chromatin immunoprecipitation in mice and primary mouse hepatocytes. We performed chromatin immunoprecipitation in livers of fasted mice to show binding of cAMP responsive element binding protein (CREB) and the glucocorticoid receptor (GR). RESULTS Fasting induced the expression of 31 genes with various roles in AA catabolism. Of them, 15 were synergistically induced by co-treatment of glucagon and corticosterone. Synergistic gene expression relied on the activity of both CREB and GR and was abolished by treatment with either insulin or fibroblast growth factor 19. Enhancers adjacent to synergistically induced genes became more accessible and were bound by CREB and GR on fasting. Akin to the gene expression pattern, gluconeogenesis from AAs was synergistically induced by glucagon and corticosterone in a CREB- and GR-dependent manner. CONCLUSIONS Transcriptional regulation of AA catabolism genes during fasting is widespread and is driven by glucagon (via CREB) and corticosterone (via GR). Glucose production in hepatocytes is also synergistically augmented, showing that glucagon alone is insufficient in fully activating gluconeogenesis.
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Affiliation(s)
- Noga Korenfeld
- Institute of Biochemistry, Food Science and Nutrition. Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of Jerusalem, Rehovot, Israel
| | - Maya Finkel
- Institute of Biochemistry, Food Science and Nutrition. Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of Jerusalem, Rehovot, Israel
| | - Nufar Buchshtab
- Institute of Biochemistry, Food Science and Nutrition. Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of Jerusalem, Rehovot, Israel
| | - Meirav Bar-Shimon
- Institute of Biochemistry, Food Science and Nutrition. Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of Jerusalem, Rehovot, Israel
| | - Meital Charni-Natan
- Institute of Biochemistry, Food Science and Nutrition. Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of Jerusalem, Rehovot, Israel
| | - Ido Goldstein
- Institute of Biochemistry, Food Science and Nutrition. Robert H. Smith Faculty of Agriculture, Food and EnvironmentThe Hebrew University of Jerusalem, Rehovot, Israel.
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14
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Kim H, Lee DS, An TH, Park TJ, Lee EW, Han BS, Kim WK, Lee CH, Lee SC, Oh KJ, Bae KH. GADD45β Regulates Hepatic Gluconeogenesis via Modulating the Protein Stability of FoxO1. Biomedicines 2021; 9:biomedicines9010050. [PMID: 33435535 PMCID: PMC7827134 DOI: 10.3390/biomedicines9010050] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/26/2020] [Accepted: 01/07/2021] [Indexed: 01/07/2023] Open
Abstract
Increased hepatic gluconeogenesis is one of the main contributors to the development of type 2 diabetes. Recently, it has been reported that growth arrest and DNA damage-inducible 45 beta (GADD45β) is induced under both fasting and high-fat diet (HFD) conditions that stimulate hepatic gluconeogenesis. Here, this study aimed to establish the molecular mechanisms underlying the novel role of GADD45β in hepatic gluconeogenesis. Both whole-body knockout (KO) mice and adenovirus-mediated knockdown (KD) mice of GADD45β exhibited decreased hepatic gluconeogenic gene expression concomitant with reduced blood glucose levels under fasting and HFD conditions, but showed a more pronounced effect in GADD45β KD mice. Further, in primary hepatocytes, GADD45β KD reduced glucose output, whereas GADD45β overexpression increased it. Mechanistically, GADD45β did not affect Akt-mediated forkhead box protein O1 (FoxO1) phosphorylation and forskolin-induced cAMP response element-binding protein (CREB) phosphorylation. Rather it increased FoxO1 transcriptional activity via enhanced protein stability of FoxO1. Further, GADD45β colocalized and physically interacted with FoxO1. Additionally, GADD45β deficiency potentiated insulin-mediated suppression of hepatic gluconeogenic genes, and it were impeded by the restoration of GADD45β expression. Our finding demonstrates GADD45β as a novel and essential regulator of hepatic gluconeogenesis. It will provide a deeper understanding of the FoxO1-mediated gluconeogenesis.
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Affiliation(s)
- Hyunmi Kim
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
- Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea
| | - Da Som Lee
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
- Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea
| | - Tae Hyeon An
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
- Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea
| | - Tae-Jun Park
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
| | - Eun-Woo Lee
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
| | - Baek Soo Han
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
- Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea
| | - Won Kon Kim
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
- Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea
| | - Chul-Ho Lee
- Laboratory Animal Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea;
| | - Sang Chul Lee
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
- Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea
| | - Kyoung-Jin Oh
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
- Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea
- Correspondence: (K.-J.O.); (K.-H.B.)
| | - Kwang-Hee Bae
- Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea; (H.K.); (D.S.L.); (T.H.A.); (T.-J.P.); (E.-W.L.); (B.S.H.); (W.K.K.); (S.C.L.)
- Department of Functional Genomics, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34141, Korea
- Correspondence: (K.-J.O.); (K.-H.B.)
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15
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Arige V, Yule DI. Pivotal role of type-1 inositol 1,4,5-trisphosphate receptor for glucagon-induced gluconeogenesis. Cell Calcium 2020; 90:102243. [PMID: 32562974 DOI: 10.1016/j.ceca.2020.102243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/08/2020] [Accepted: 06/08/2020] [Indexed: 10/24/2022]
Abstract
We highlight a recent paper which documents the important role that Ca2+ release through type-1 Inositol 1,4,5-trisphosphate receptor (IP3R1) plays in the acute regulation by glucagon of gluconeogenesis in hepatocytes. The specificity is likely the result of discrete localization close to mitochondria and PKA-dependent phosphorylation of IP3R1 which enhances Ca2+ release.
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Affiliation(s)
- Vikas Arige
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY, 14642, United States
| | - David I Yule
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY, 14642, United States.
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16
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Payne JA, Proszkowiec-Weglarz M, Ellestad LE. Delayed access to feed alters expression of genes associated with carbohydrate and amino acid utilization in newly hatched broiler chicks. Am J Physiol Regul Integr Comp Physiol 2019; 317:R864-R878. [PMID: 31596116 PMCID: PMC6962625 DOI: 10.1152/ajpregu.00117.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 12/24/2022]
Abstract
Newly hatched chicks must transition from lipid-rich yolk to carbohydrate-rich feed as their primary nutrient source, and posthatch delays in access to feed can have long-term negative consequences on growth and metabolism. In this study, impacts of delayed access to feed at hatch on expression of genes related to nutrient uptake and utilization in two metabolically important tissues, liver and muscle, were determined in broiler (meat-type) chickens. Hatched chicks were given access to feed within 3 h (fed) or delayed access to feed for 48 h (delayed fed), and liver and breast muscle were collected from males at hatch and 4 h, 1 day, 2 days, 4 days, and 8 days posthatch for analysis of gene expression. Differential expression of carbohydrate response element-binding protein and peroxisome proliferator-activated receptor-γ in muscle and liver was observed, with results indicating a transitional delay from lipid to carbohydrate metabolism when hatched chicks were not given immediate access to feed. Extended upregulation of insulin receptor mRNA was observed in both tissues in delayed fed birds, suggesting increased sensitivity to circulating levels of the hormone. Developmental delays in expression patterns of cationic amino acid transporters 1 and 2 in both tissues and large neutral amino acid transporter 1 in muscle were also apparent when immediate feed access was prevented. These data suggest that delayed transition to carbohydrate use and altered nutrient transport and utilization within liver and breast muscle are key factors negatively affecting growth and metabolism following delayed feed access in broiler chickens.
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Affiliation(s)
- Jason A Payne
- Department of Poultry Science, University of Georgia, Athens, Georgia
| | - Monika Proszkowiec-Weglarz
- Animal Biosciences and Biotechnology Laboratory, United States Department of Agriculture, Agricultural Research Services, Northeast Area, Beltsville, Maryland
| | - Laura E Ellestad
- Department of Poultry Science, University of Georgia, Athens, Georgia
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