Relationship between AMPK and the transcriptional balance of clock-related genes in skeletal muscle

Vieira, Elaine; Nilsson, Elisabeth; Nerstedt, Annika; Ormestad, Mattias; Long, Yun; García-Rovés, Pablo M.; Zierath, Juleen R.; Mahlapuu, Margit

doi:10.1152/ajpendo.90510.2008

Cited by 63 publications

(49 citation statements)

References 35 publications

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“…In contrast, significant feeding, RER, and metabolic rhythms were detected in all B-SAP controls during both LD and DD. Metabolic rate and RER have been shown to be rhythmic in controls during LD (69,90), but they have not been examined previously in DD.…”

Section: Discussionmentioning

confidence: 98%

Leptin-sensitive neurons in the arcuate nuclei contribute to endogenous feeding rhythms

Wiater

Oostrom

et al. 2012

American Journal of Physiology-Regulatory, Integrative and Comp

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Li AJ, Wiater MF, Oostrom MT, Smith BR, Wang Q, Dinh TT, Roberts BL, Jansen HT, Ritter S. Leptin-sensitive neurons in the arcuate nuclei contribute to endogenous feeding rhythms. Am J Physiol Regul Integr Comp Physiol 302: R1313-R1326, 2012. First published April 4, 2012 doi:10.1152/ajpregu.00086.2012.-Neural sites that interact with the suprachiasmatic nuclei (SCN) to generate rhythms of unrestricted feeding remain unknown. We used the targeted toxin, leptin conjugated to saporin (Lep-SAP), to examine the importance of leptin receptor-B (LepR-B)-expressing neurons in the arcuate nucleus (Arc) for generation of circadian feeding rhythms. Rats given Arc Lep-SAP injections were initially hyperphagic and rapidly became obese (the "dynamic phase" of weight gain). During this phase, Lep-SAP rats were arrhythmic under 12:12-h light-dark (LD) conditions, consuming 59% of their total daily intake during the daytime, compared with 36% in blank-SAP (B-SAP) controls. Lep-SAP rats were also arrhythmic in continuous dark (DD), while significant circadian feeding rhythms were detected in all B-SAP controls. Approximately 8 wk after injection, Lep-SAP rats remained obese but transitioned into a "static phase" of weight gain marked by attenuation of their hyperphagia and rate of weight gain. In this phase, Arc Lep-SAP rats exhibited circadian feeding rhythms under LD conditions, but were arrhythmic in continuous light (LL) and DD. Lep-SAP injections into the ventromedial hypothalamic nucleus did not cause hyperphagia, obesity, or arrhythmic feeding in either LD or DD. Electrolytic lesion of the SCN produced feeding arrhythmia in DD but not hyperphagia or obesity. Results suggest that both Arc Lep-SAP neurons and SCN are required for generation of feeding rhythms entrained to photic cues, while also revealing an essential role for the Arc in maintaining circadian rhythms of ad libitum feeding independent of light entrainment.

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Section: Discussionmentioning

confidence: 98%

Leptin-sensitive neurons in the arcuate nuclei contribute to endogenous feeding rhythms

Wiater

Oostrom

et al. 2012

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Samples were subjected to the following conditions: 10 min at 95°C, 40 cycles of 10 s at 95°C, 7 s at 60°C and 12 s at 72°C, and a melting curve of 63 to 95°C with a slope of 0.1°C/s. The housekeeping gene Rplp0 (ribosomal protein large P0) was used as the endogenous control for quantification [18]. Leptin treatment did not affect expression of this gene (ESM Fig.…”

Section: Methodsmentioning

confidence: 99%

Leptin downregulates expression of the gene encoding glucagon in alphaTC1-9 cells and mouse islets

et al. 2011

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Aims/hypothesis Leptin, released by adipocytes, can modulate glucose homeostasis through direct actions on pancreatic alpha and beta cells. Although this hormone rapidly regulates alpha cell exocytosis, its long-term effects on glucagon gene expression are currently unknown. Methods We analysed glucagon mRNA levels and protein content in alphaTC1-9 cells and isolated mouse islets cultured with leptin, as well as in islets from mice treated in vivo with leptin. We also studied the involvement of the signal transducers and activators of transcription (STAT) pathway by western blot, immunofluorescence and interference RNA. Results Leptin incubation (0.0625-18.75 nmol/l) for 24 h inhibited glucagon gene expression in alphaTC1-9 cells. This inhibitory effect was also observed in isolated mouse islets cultured with leptin, as well as in islets from mice treated with leptin for 5 days. In contrast, no changes were detected in islets from db/db mice, which lack leptin receptors. Leptin treatment also reduced the glucagon protein content in alphaTC1-9 cells and mouse islets. Moreover, leptin induced phosphorylation of STAT3 and its translocation to the nucleus, which was confirmed by western blot analysis in alphaTC1-9 cells and by immunofluorescence in isolated alpha cells. Interestingly, the effect of leptin on glucagon mRNA levels was significantly reduced by Stat3 knockdown. In contrast, pharmacological inhibition of the phosphoinositide 3-kinase pathway did not affect leptin actions. Conclusions/interpretation Our results demonstrate that leptin can regulate glucagon gene expression in alpha cells via a STAT3 pathway, and are important for understanding the role of leptin in glucose homeostasis.

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“…myoD and IGF-I (Miller et al, 2007). AMPK signalling cascades, which regulate cellular energy status (Fig.2), may also control the transcription of clock-related genes (Vieira et al, 2008). formation and myosin accumulation in C2C12 cells (Williamson et al, 2009) and increased the expression of MuRF1 and MAFbx (Tong et al, 2009).…”

Section: Perspectives For Future Researchmentioning

confidence: 99%

Growth and the regulation of myotomal muscle mass in teleost fish

Johnston

Bower

Macqueen

2011

Journal of Experimental Biology

406

333

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SummaryTeleost muscle first arises in early embryonic life and its development is driven by molecules present in the egg yolk and modulated by environmental stimuli including temperature and oxygen. Several populations of myogenic precursor cells reside in the embryonic somite and external cell layer and contribute to muscle fibres in embryo, larval, juvenile and adult stages. Many signalling proteins and transcription factors essential for these events are known. In all cases, myogenesis involves myoblast proliferation, migration, fusion and terminal differentiation. Maturation of the embryonic muscle is associated with motor innervation and the development of a scaffold of connective tissue and complex myotomal architecture needed to generate swimming behaviour. Adult muscle is a heterogeneous tissue composed of several cell types that interact to affect growth patterns. The development of capillary and lymphatic circulations and extramuscular organs -notably the gastrointestinal, endocrine, neuroendocrine and immune systems -serves to increase information exchange between tissues and with the external environment, adding to the complexity of growth regulation. Teleosts often exhibit an indeterminate growth pattern, with body size and muscle mass increasing until mortality or senescence occurs. The dramatic increase in myotomal muscle mass between embryo and adult requires the continuous production of muscle fibres until 40-50% of the maximum body length is reached. Sarcomeric proteins can be mobilised as a source of amino acids for energy metabolism by other tissues and for gonad generation, requiring the dynamic regulation of muscle mass throughout the life cycle. The metabolic and contractile phenotypes of muscle fibres also show significant plasticity with respect to environmental conditions, migration and spawning. Many genes regulating muscle growth are found as multiple copies as a result of paralogue retention following whole-genome duplication events in teleost lineages. The extent to which indeterminate growth, ectothermy and paralogue preservation have resulted in modifications of the genetic pathways regulating muscle growth in teleosts compared to mammals largely remains unknown. This review describes the use of compensatory growth models, transgenesis and tissue culture to explore the mechanisms of muscle growth in teleosts and provides some perspectives on future research directions.

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Relationship between AMPK and the transcriptional balance of clock-related genes in skeletal muscle

Cited by 63 publications

References 35 publications

Leptin-sensitive neurons in the arcuate nuclei contribute to endogenous feeding rhythms

Leptin-sensitive neurons in the arcuate nuclei contribute to endogenous feeding rhythms

Leptin downregulates expression of the gene encoding glucagon in alphaTC1-9 cells and mouse islets

Growth and the regulation of myotomal muscle mass in teleost fish

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