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JAK2/STAT3 Pathway is Required for α7nAChR-Dependent Expression of POMC and AGRP Neuropeptides in Male Mice.
Cell Physiol Biochem. 2019; 53(4):701-712.CP

Abstract

BACKGROUND/AIMS

Cholinergic signalling mediated by the activation of muscarinic and nicotinic receptors has been described in the literature as a classic and important signalling pathway in the regulation of the inflammatory response. Recent research has investigated the role of acetylcholine, the physiological agonist of these receptors, in the control of energy homeostasis at the central level. Studies have shown that mice that do not express acetylcholine in brain regions regulating energy homeostasis present with excessive weight gain and hyperphagia. However, it has not yet been well-described in the literature which cholinergic receptor subunits are involved in this response; moreover, the signalling pathways responsible for the observed effects are not fully delineated. The hypothalamus is the regulating centre of energy homeostasis, and the α7 subunit of the nicotinic acetylcholine receptor (α7nAChR) is highly expressed in this region. When active, α7nAChR recruits proteins such as JAK2/STAT3 to mediate its signalling; the same intracellular components are required by leptin, an anorexigenic hormone. The aim of the present study was to evaluate the role of the hypothalamic α7nAChR in the control of energy homeostasis.

METHODS

The work was performed on Swiss male mice. Initially, using immunofluorescent staining on brain sections, the presence of α7nAChR in hypothalamic cells regulating energy homeostasis was evaluated. Animals were submitted to stereotaxis in the lateral ventricle and intracerebroventricular stimulation (ICV) was used for the administration of an agonist (PNU) or antagonist (α-bungarotoxin) of α7nAChR. Metabolic parameters were evaluated and the expression of neuropeptides was evaluated in the hypothalamus by real-time PCR and western blot. The expression of hypothalamic neuropeptides was evaluated in mice treated with siRNA or inhibitors of JAK2/STAT3 (AG490 and STATTIC) proteins. We also evaluated food intake in α7nAChR knockout animals (α7KO). Additionally, in mouse hypothalamic cell culture (the mypHoA-POMC/GFP lineage), we evaluated the expression of neuropeptides and pSTAT3 after stimulation with PNU.

RESULTS

Our results indicate co-localisation of α7nAChR with α-MSH, AgRP and NPY in hypothalamic cells. Pharmacological activation of α7nAChR reduced food intake and increased hypothalamic POMC expression and decreased NPY and AgRP mRNA levels and the protein content of pAMPK. Inhibition of α7nAChR with an antagonist increased the mRNA content of NPY and AgRP. Inhibition of α7nAChR with siRNA led to the suppression of POMC expression and an increase in AgRP mRNA levels. α7KO mice showed no changes in food intake. Inhibition of proteins involved in the JAK2/STAT3 signalling pathway reversed the effects observed after PNU stimulation. POMC-GFP cells, when treated with PNU, showed increased POMC expression and nuclear translocation of pSTAT3.

CONCLUSION

Thus, selective activation of α7nAChR is able to modulate important markers of the response to food intake, suggesting that α7nAChR activation can suppress the expression of orexigenic markers and favour the expression of anorexics using the intracellular JAK2/STAT3 machinery.

Authors+Show Affiliations

School of Applied Sciences, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil. Obesity and Comorbidities Research Centre, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil. Obesity and Comorbidities Research Centre, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil. Obesity and Comorbidities Research Centre, University of Campinas, Campinas, Brazil.School of Applied Sciences, University of Campinas, Campinas, Brazil, torsoni@unicamp.br. Obesity and Comorbidities Research Centre, University of Campinas, Campinas, Brazil.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31592599

Citation

Souza, Camilla Mendes, et al. "JAK2/STAT3 Pathway Is Required for α7nAChR-Dependent Expression of POMC and AGRP Neuropeptides in Male Mice." Cellular Physiology and Biochemistry : International Journal of Experimental Cellular Physiology, Biochemistry, and Pharmacology, vol. 53, no. 4, 2019, pp. 701-712.
Souza CM, do Amaral CL, Souza SC, et al. JAK2/STAT3 Pathway is Required for α7nAChR-Dependent Expression of POMC and AGRP Neuropeptides in Male Mice. Cell Physiol Biochem. 2019;53(4):701-712.
Souza, C. M., do Amaral, C. L., Souza, S. C., de Souza, A. C. P., de Cássia Alves Martins, I., Contieri, L. S., Milanski, M., Torsoni, A. S., Ignacio-Souza, L. M., & Torsoni, M. A. (2019). JAK2/STAT3 Pathway is Required for α7nAChR-Dependent Expression of POMC and AGRP Neuropeptides in Male Mice. Cellular Physiology and Biochemistry : International Journal of Experimental Cellular Physiology, Biochemistry, and Pharmacology, 53(4), 701-712. https://doi.org/10.33594/000000166
Souza CM, et al. JAK2/STAT3 Pathway Is Required for α7nAChR-Dependent Expression of POMC and AGRP Neuropeptides in Male Mice. Cell Physiol Biochem. 2019;53(4):701-712. PubMed PMID: 31592599.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - JAK2/STAT3 Pathway is Required for α7nAChR-Dependent Expression of POMC and AGRP Neuropeptides in Male Mice. AU - Souza,Camilla Mendes, AU - do Amaral,Camilla Libardi, AU - Souza,Suleyma Costa, AU - de Souza,Anelise Cristina Parras, AU - de Cássia Alves Martins,Isis, AU - Contieri,Leticia Sanches, AU - Milanski,Marciane, AU - Torsoni,Adriana Souza, AU - Ignacio-Souza,Leticia Martins, AU - Torsoni,Marcio Alberto, PY - 2019/10/02/accepted PY - 2019/10/9/entrez PY - 2019/10/9/pubmed PY - 2019/11/20/medline KW - Energy homeostasis KW - Hypothalamus KW - Mice KW - nAChR KW - α7nAChR SP - 701 EP - 712 JF - Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology JO - Cell. Physiol. Biochem. VL - 53 IS - 4 N2 - BACKGROUND/AIMS: Cholinergic signalling mediated by the activation of muscarinic and nicotinic receptors has been described in the literature as a classic and important signalling pathway in the regulation of the inflammatory response. Recent research has investigated the role of acetylcholine, the physiological agonist of these receptors, in the control of energy homeostasis at the central level. Studies have shown that mice that do not express acetylcholine in brain regions regulating energy homeostasis present with excessive weight gain and hyperphagia. However, it has not yet been well-described in the literature which cholinergic receptor subunits are involved in this response; moreover, the signalling pathways responsible for the observed effects are not fully delineated. The hypothalamus is the regulating centre of energy homeostasis, and the α7 subunit of the nicotinic acetylcholine receptor (α7nAChR) is highly expressed in this region. When active, α7nAChR recruits proteins such as JAK2/STAT3 to mediate its signalling; the same intracellular components are required by leptin, an anorexigenic hormone. The aim of the present study was to evaluate the role of the hypothalamic α7nAChR in the control of energy homeostasis. METHODS: The work was performed on Swiss male mice. Initially, using immunofluorescent staining on brain sections, the presence of α7nAChR in hypothalamic cells regulating energy homeostasis was evaluated. Animals were submitted to stereotaxis in the lateral ventricle and intracerebroventricular stimulation (ICV) was used for the administration of an agonist (PNU) or antagonist (α-bungarotoxin) of α7nAChR. Metabolic parameters were evaluated and the expression of neuropeptides was evaluated in the hypothalamus by real-time PCR and western blot. The expression of hypothalamic neuropeptides was evaluated in mice treated with siRNA or inhibitors of JAK2/STAT3 (AG490 and STATTIC) proteins. We also evaluated food intake in α7nAChR knockout animals (α7KO). Additionally, in mouse hypothalamic cell culture (the mypHoA-POMC/GFP lineage), we evaluated the expression of neuropeptides and pSTAT3 after stimulation with PNU. RESULTS: Our results indicate co-localisation of α7nAChR with α-MSH, AgRP and NPY in hypothalamic cells. Pharmacological activation of α7nAChR reduced food intake and increased hypothalamic POMC expression and decreased NPY and AgRP mRNA levels and the protein content of pAMPK. Inhibition of α7nAChR with an antagonist increased the mRNA content of NPY and AgRP. Inhibition of α7nAChR with siRNA led to the suppression of POMC expression and an increase in AgRP mRNA levels. α7KO mice showed no changes in food intake. Inhibition of proteins involved in the JAK2/STAT3 signalling pathway reversed the effects observed after PNU stimulation. POMC-GFP cells, when treated with PNU, showed increased POMC expression and nuclear translocation of pSTAT3. CONCLUSION: Thus, selective activation of α7nAChR is able to modulate important markers of the response to food intake, suggesting that α7nAChR activation can suppress the expression of orexigenic markers and favour the expression of anorexics using the intracellular JAK2/STAT3 machinery. SN - 1421-9778 UR - https://www.unboundmedicine.com/medline/citation/31592599/JAK2/STAT3_Pathway_is_Required_for_α7nAChR_Dependent_Expression_of_POMC_and_AGRP_Neuropeptides_in_Male_Mice_ L2 - https://www.cellphysiolbiochem.com/Articles/?DOI=10.33594/000000166 DB - PRIME DP - Unbound Medicine ER -