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Pintwala SK, Fraigne JJ, Belsham DD, Peever JH. Immortal orexin cell transplants restore motor-arousal synchrony during cataplexy. Curr Biol 2023; 33:1550-1564.e5. [PMID: 37044089 DOI: 10.1016/j.cub.2023.03.077] [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: 12/08/2022] [Revised: 03/11/2023] [Accepted: 03/27/2023] [Indexed: 04/14/2023]
Abstract
Waking behaviors such as sitting or standing require suitable levels of muscle tone. But it is unclear how arousal and motor circuits communicate with one another so that appropriate motor tone occurs during wakefulness. Cataplexy is a peculiar condition in which muscle tone is involuntarily lost during normal periods of wakefulness. Cataplexy therefore provides a unique opportunity for identifying the signaling mechanisms that synchronize motor and arousal behaviors. Cataplexy occurs when hypothalamic orexin neurons are lost in narcolepsy; however, it is unclear if motor-arousal decoupling in cataplexy is directly or indirectly caused by orexin cell loss. Here, we used genomic, proteomic, chemogenetic, electrophysiological, and behavioral assays to determine if grafting orexin cells into the brain of cataplectic (i.e., orexin-/-) mice restores normal motor-arousal behaviors by preventing cataplexy. First, we engineered immortalized orexin cells and found that they not only produce and release orexin but also exhibit a gene profile that mimics native orexin neurons. Second, we show that engineered orexin cells thrive and integrate into host tissue when transplanted into the brain of mice. Next, we found that grafting only 200-300 orexin cells into the dorsal raphe nucleus-a region densely innervated by native orexin neurons-reduces cataplexy. Last, we show that real-time chemogenetic activation of orexin cells restores motor-arousal synchrony by preventing cataplexy. We suggest that orexin signaling is critical for arousal-motor synchrony during wakefulness and that the dorsal raphe plays a pivotal role in coupling arousal and motor behaviors.
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Affiliation(s)
- Sara K Pintwala
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Jimmy J Fraigne
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Denise D Belsham
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Obstetrics and Gynecology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - John H Peever
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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Lieu CV, Loganathan N, Belsham DD. Mechanisms Driving Palmitate-Mediated Neuronal Dysregulation in the Hypothalamus. Cells 2021; 10:3120. [PMID: 34831343 PMCID: PMC8617942 DOI: 10.3390/cells10113120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 12/17/2022] Open
Abstract
The hypothalamus maintains whole-body homeostasis by integrating information from circulating hormones, nutrients and signaling molecules. Distinct neuronal subpopulations that express and secrete unique neuropeptides execute the individual functions of the hypothalamus, including, but not limited to, the regulation of energy homeostasis, reproduction and circadian rhythms. Alterations at the hypothalamic level can lead to a myriad of diseases, such as type 2 diabetes mellitus, obesity, and infertility. The excessive consumption of saturated fatty acids can induce neuroinflammation, endoplasmic reticulum stress, and resistance to peripheral signals, ultimately leading to hyperphagia, obesity, impaired reproductive function and disturbed circadian rhythms. This review focuses on the how the changes in the underlying molecular mechanisms caused by palmitate exposure, the most commonly consumed saturated fatty acid, and the potential involvement of microRNAs, a class of non-coding RNA molecules that regulate gene expression post-transcriptionally, can result in detrimental alterations in protein expression and content. Studying the involvement of microRNAs in hypothalamic function holds immense potential, as these molecular markers are quickly proving to be valuable tools in the diagnosis and treatment of metabolic disease.
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Affiliation(s)
- Calvin V. Lieu
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada; (C.V.L.); (N.L.)
| | - Neruja Loganathan
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada; (C.V.L.); (N.L.)
| | - Denise D. Belsham
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada; (C.V.L.); (N.L.)
- Departments of Obstetrics/Gynecology and Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
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Spexin: Its role, regulation, and therapeutic potential in the hypothalamus. Pharmacol Ther 2021; 233:108033. [PMID: 34763011 DOI: 10.1016/j.pharmthera.2021.108033] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 12/14/2022]
Abstract
Spexin is the most recently discovered member of the galanin/kisspeptin/spexin family of peptides. This 14-amino acid peptide is highly conserved and is implicated in homeostatic functions including, but not limited to, metabolism, energy homeostasis, and reproduction. Spexin is expressed by neurons in the hypothalamus, which coordinate energy homeostasis and reproduction. Critically, levels of spexin appear to be altered in disorders related to energy homeostasis and reproduction, such as obesity, diabetes, and polycystic ovarian syndrome. In this review, we discuss the evidence for the involvement of spexin in the hypothalamic control of energy homeostasis and reproduction. The anorexigenic properties of spexin have been attributed to its effects on the energy-regulating neuropeptide Y/agouti-related peptide neurons and proopiomelanocortin neurons. While the role of spexin in reproduction remains unclear, there is evidence that gonadotropin-releasing hormone expressing neurons may produce and respond to spexin. Furthermore, we discuss the disorders and concomitant treatments, which have been reported to alter spexin expression, as well as the underlying signaling mechanisms that may be involved. Finally, we discuss the biochemical basis of spexin, its interaction with its cognate receptors, and how this information can be adapted to develop therapeutics for disorders related to the alteration of energy homeostasis and reproduction.
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McIlwraith EK, Belsham DD. Hypothalamic reproductive neurons communicate through signal transduction to control reproduction. Mol Cell Endocrinol 2020; 518:110971. [PMID: 32750397 DOI: 10.1016/j.mce.2020.110971] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/11/2020] [Accepted: 07/28/2020] [Indexed: 12/11/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus coordinate fertility and puberty. In order to achieve successful reproductive capacity, they receive signals from the periphery and from other hypothalamic neurons that coordinate energy homeostasis. Hormones, such as estradiol, insulin, leptin, and adiponectin, act directly or indirectly on GnRH and its associated reproductive neurons. Nutrients like glucose and fatty acids can also affect reproductive neurons to signal nutrient availability. Additionally, acute and chronic inflammation is reported to detrimentally affect GnRH and kisspeptin expression. All of these cues activate signal transduction pathways within neurons that lead to the changes in GnRH neuronal function. The signalling pathways can also be dysregulated by endocrine disrupting chemicals, which impair fertility by misappropriating common signalling pathways. The complex mechanisms controlling the levels of GnRH during the reproductive cycle rely on a carefully orchestrated set of signal transduction events to regulate the positive and negative feedback arms of the hypothalamic-pituitary-gonadal axis. If these signalling events are dysregulated, this will result is a downregulatory event leading to hypogonadal hypogonadism with decreased or absent fertility. Therefore, an understanding of the mechanisms involved in distinct neuronal signalling could provide an advantage to inform therapeutic interventions for infertility and reproductive disorders.
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Affiliation(s)
- Emma K McIlwraith
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Denise D Belsham
- Department of Physiology, University of Toronto, Toronto, ON, Canada; Obstetrics and Gynaecology and Medicine, University of Toronto, Toronto, ON, Canada.
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5
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Wang L, Tran A, Lee J, Belsham DD. Palmitate differentially regulates Spexin, and its receptors Galr2 and Galr3, in GnRH neurons through mechanisms involving PKC, MAPKs, and TLR4. Mol Cell Endocrinol 2020; 518:110991. [PMID: 32841709 DOI: 10.1016/j.mce.2020.110991] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/03/2020] [Accepted: 08/12/2020] [Indexed: 02/06/2023]
Abstract
The function of the gonadotropin-releasing hormone (GnRH) neuron is critical to maintain reproductive function and a significant decrease in GnRH can lead to disorders affecting fertility, including hypogonadotropic hypogonadism. Spexin (SPX) is a novel hypothalamic neuropeptide that exerts inhibitory effects on reproduction and feeding by acting through galanin receptor 2 (GALR2) and galanin receptor 3 (GALR3). Fatty acids can act as nutritional signals that regulate the hypothalamic-pituitary-gonadal (HPG) axis, and elevated levels of circulating saturated fatty acids associated with high fat diet (HFD)-feeding have been shown to induce neuroinflammation, endoplasmic reticulum stress and hormonal resistance in the hypothalamus, as well as alter neuropeptide expression. We previously demonstrated that palmitate, the most common saturated fatty acid in a HFD, elevates the expression of Spx, Galr2 and Galr3 mRNA in a model of appetite-regulating neuropeptide Y hypothalamic neurons. Here, we found that Spx, Galr2 and Galr3 mRNA were also significantly induced by palmitate in a model of reproductive GnRH neurons, mHypoA-GnRH/GFP. As a follow-up to our previous report, we examined the molecular pathways by which Spx and galanin receptor mRNA was regulated in this cell line. Furthermore, we performed inhibitor studies, which revealed that the effect of palmitate on Spx and Galr3 mRNA involved activation of the innate immune receptor TLR4, and we detected differential regulation of the three genes by the protein kinases PKC, JNK, ERK, and p38. However, the intracellular metabolism of palmitate to ceramide did not appear to be involved in the palmitate-mediated gene regulation. Overall, this suggests that SPX may play a role in reproduction at the level of the hypothalamus and the pathways by which Spx, Galr2 and Galr3 are altered by fatty acids could provide insight into the mechanisms underlying reproductive dysfunction in obesity.
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Affiliation(s)
- Lu Wang
- Departments of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada
| | - Andy Tran
- Departments of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada
| | - Juliette Lee
- Departments of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada
| | - Denise D Belsham
- Departments of Physiology, Faculty of Medicine, University of Toronto, Ontario, Canada; Medicine, Faculty of Medicine, University of Toronto, Ontario, Canada; Obstetrics and Gynecology, Faculty of Medicine, University of Toronto, Ontario, Canada.
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Oshimo Y, Munetomo A, Magata F, Suetomi Y, Sonoda S, Takeuchi Y, Tsukamura H, Ohkura S, Matsuda F. Estrogen increases KISS1 expression in newly generated immortalized KISS1-expressing cell line derived from goat preoptic area. J Reprod Dev 2020; 67:15-23. [PMID: 33100283 PMCID: PMC7902218 DOI: 10.1262/jrd.2020-053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Kisspeptin neurons located in the hypothalamic preoptic area (POA) are suggested to be responsible for the induction of the gonadotropin-releasing hormone
(GnRH) surge and the following luteinizing hormone (LH) surge to regulate female mammals’ ovulation. Accumulating evidence demonstrates that the preovulatory
level of estrogen activates the POA kisspeptin neurons (estrogen positive feedback), which in turn induces a GnRH/LH surge. This study aimed to derive a cell
line from goat POA kisspeptin neurons as an in vitro model to analyze the estrogen positive feedback mechanism in ruminants. Neuron-derived
cell clones obtained by the immortalization of POA tissue from a female Shiba goat fetus were analyzed for the expression of kisspeptin (KISS1)
and estrogen receptor α (ESR1) genes using quantitative real-time reverse transcription-polymerase chain reaction and three cell clones were
selected as POA kisspeptin neuron cell line candidates. One cell line (GP64) out of the three clones showed significant increase in the KISS1
level by incubation with estradiol for 24 h, indicating that the GP64 cells mimic endogenous goat POA kisspeptin neurons. The GP64 cells showed
immunoreactivities for kisspeptin and estrogen receptor α and retained a stable growth rate throughout three passages. Further, intracellular calcium levels in
the GP64 cells were increased by the KCl challenge, indicating their neurosecretory ability. In conclusion, we generated a new KISS1-expressing
cell line derived from goat POA. The current GP64 cell line could be a useful model to elucidate the estrogen positive feedback mechanism responsible for the
GnRH/LH surge generation in ruminants.
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Affiliation(s)
- Yukina Oshimo
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Arisa Munetomo
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Fumie Magata
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yuta Suetomi
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Shuhei Sonoda
- Laboratory of Veterinary Ethology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yukari Takeuchi
- Laboratory of Veterinary Ethology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Satoshi Ohkura
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Fuko Matsuda
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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Stanley S, Moheet A, Seaquist ER. Central Mechanisms of Glucose Sensing and Counterregulation in Defense of Hypoglycemia. Endocr Rev 2019; 40:768-788. [PMID: 30689785 PMCID: PMC6505456 DOI: 10.1210/er.2018-00226] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 01/17/2019] [Indexed: 12/12/2022]
Abstract
Glucose homeostasis requires an organism to rapidly respond to changes in plasma glucose concentrations. Iatrogenic hypoglycemia as a result of treatment with insulin or sulfonylureas is the most common cause of hypoglycemia in humans and is generally only seen in patients with diabetes who take these medications. The first response to a fall in glucose is the detection of impending hypoglycemia by hypoglycemia-detecting sensors, including glucose-sensing neurons in the hypothalamus and other regions. This detection is then linked to a series of neural and hormonal responses that serve to prevent the fall in blood glucose and restore euglycemia. In this review, we discuss the current state of knowledge about central glucose sensing and how detection of a fall in glucose leads to the stimulation of counterregulatory hormone and behavior responses. We also review how diabetes and recurrent hypoglycemia impact glucose sensing and counterregulation, leading to development of impaired awareness of hypoglycemia in diabetes.
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Affiliation(s)
- Sarah Stanley
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Amir Moheet
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Elizabeth R Seaquist
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
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Kowalchuk C, Kanagasundaram P, Belsham DD, Hahn MK. Antipsychotics differentially regulate insulin, energy sensing, and inflammation pathways in hypothalamic rat neurons. Psychoneuroendocrinology 2019; 104:42-48. [PMID: 30802709 DOI: 10.1016/j.psyneuen.2019.01.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/16/2019] [Accepted: 01/31/2019] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Second generation antipsychotic (AP)s remain the gold-standard treatment for schizophrenia and are widely used on- and off-label for other psychiatric illnesses. However, these agents cause serious metabolic side-effects. The hypothalamus is the primary brain region responsible for whole body energy regulation, and disruptions in energy sensing (e.g. insulin signaling) and inflammation in this brain region have been implicated in the development of insulin resistance and obesity. To elucidate mechanisms by which APs may be causing metabolic dysregulation, we explored whether these agents can directly impact energy sensing and inflammation in hypothalamic neurons. METHODS The rat hypothalamic neuronal cell line, rHypoE-19, was treated with olanzapine (0.25-100 uM), clozapine (2.5-100 uM) or aripiprazole (5-20 uM). Western blots measured the energy sensing protein AMPK, components of the insulin signaling pathway (AKT, GSK3β), and components of the MAPK pathway (ERK1/2, JNK, p38). Quantitative real-time PCR was performed to determine changes in the mRNA expression of interleukin (IL)-6, IL-10 and brain derived neurotrophic factor (BDNF). RESULTS Olanzapine (100 uM) and clozapine (100, 20 uM) significantly increased pERK1/2 and pJNK protein expression, while aripiprazole (20 uM) only increased pJNK. Clozapine (100 uM) and aripiprazole (5 and 20 uM) significantly increased AMPK phosphorylation (an orexigenic energy sensor), and inhibited insulin-induced phosphorylation of AKT. Olanzapine (100 uM) treatment caused a significant increase in IL-6 while aripiprazole (20 uM) significantly decreased IL-10. Olanzapine (100 uM) and aripiprazole (20 uM) increased BDNF expression. CONCLUSIONS We demonstrate that antipsychotics can directly regulate insulin, energy sensing, and inflammatory pathways in hypothalamic neurons. Increased MAPK activation by all antipsychotics, alongside olanzapine-associated increases in IL-6, and aripiprazole-associated decreases in IL-10, suggests induction of pro-inflammatory pathways. Clozapine and aripiprazole inhibition of insulin-stimulated pAKT and increases in AMPK phosphorylation (an orexigenic energy sensor) suggests impaired insulin action and energy sensing. Conversely, olanzapine and aripiprazole increased BDNF, which would be expected to be metabolically beneficial. Overall, our findings suggest differential effects of antipsychotics on hypothalamic neuroinflammation and energy sensing.
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Affiliation(s)
- Chantel Kowalchuk
- Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, M5T 1R8, Canada; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Pruntha Kanagasundaram
- Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, M5T 1R8, Canada
| | - Denise D Belsham
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
| | - Margaret K Hahn
- Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, M5T 1R8, Canada; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, M5T 1R8, Canada.
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9
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Spergel DJ. Modulation of Gonadotropin-Releasing Hormone Neuron Activity and Secretion in Mice by Non-peptide Neurotransmitters, Gasotransmitters, and Gliotransmitters. Front Endocrinol (Lausanne) 2019; 10:329. [PMID: 31178828 PMCID: PMC6538683 DOI: 10.3389/fendo.2019.00329] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 05/07/2019] [Indexed: 12/18/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neuron activity and GnRH secretion are essential for fertility in mammals. Here, I review findings from mouse studies on the direct modulation of GnRH neuron activity and GnRH secretion by non-peptide neurotransmitters (GABA, glutamate, dopamine, serotonin, norepinephrine, epinephrine, histamine, ATP, adenosine, and acetylcholine), gasotransmitters (nitric oxide and carbon monoxide), and gliotransmitters (prostaglandin E2 and possibly GABA, glutamate, and ATP). These neurotransmitters, gasotransmitters, and gliotransmitters have been shown to directly modulate activity and/or GnRH secretion in GnRH neurons in vivo or ex vivo (brain slices), from postnatal through adult mice, or in embryonic or immortalized mouse GnRH neurons. However, except for GABA, nitric oxide, and prostaglandin E2, which appear to be essential for normal GnRH neuron activity, GnRH secretion, and fertility in males and/or females, the biological significance of their direct modulation of GnRH neuron activity and/or GnRH secretion in the central regulation of reproduction remains largely unknown and requires further exploration.
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Levi NJ, Wilson CW, Redweik GAJ, Gray NW, Grzybowski CW, Lenkey JA, Moseman AW, Bertsch AD, Dao N, Walsh HE. Obesity-related cellular stressors regulate gonadotropin releasing hormone gene expression via c-Fos/AP-1. Mol Cell Endocrinol 2018; 478:97-105. [PMID: 30063946 DOI: 10.1016/j.mce.2018.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/14/2018] [Accepted: 07/25/2018] [Indexed: 12/15/2022]
Abstract
Obesity is a risk factor for infertility, but mechanisms underlying this risk are unclear. Fertility is regulated by hypothalamic gonadotropin-releasing hormone, encoded by the Gnrh1 gene. Because obesity promotes endoplasmic reticulum (ER) stress, we sought to determine how tunicamycin-induced ER stress affected Gnrh1 gene expression in the mouse hypothalamic cell line GT1-7. Tunicamycin repressed expression of Gnrh1 in a PKC- and JNK-dependent manner, while upregulating expression of a known Gnrh1 repressor, Fos. Obesity is associated with increased circulating free fatty acids, and exposure to palmitate promoted ER stress and inflammation. Fos expression increased with palmitate dose, but Gnrh1 expression was upregulated with low-dose palmitate and repressed with high-dose palmitate. Using a small molecule inhibitor, we determined that AP-1 was required for Gnrh1 repression by high-dose palmitate or tunicamycin-induced ER stress. These findings suggest that hypogonadism driven by decreased hypothalamic GnRH may be a component of obesity-related infertility.
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Affiliation(s)
- Noah J Levi
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Christopher W Wilson
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Graham A J Redweik
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Nathan W Gray
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Cody W Grzybowski
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Joseph A Lenkey
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Anthony W Moseman
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Alec D Bertsch
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Nhien Dao
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA
| | - Heidi E Walsh
- Department of Biology, Wabash College, PO Box 352, Crawfordsville, IN, 47933, USA.
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11
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Mcilwraith EK, Belsham DD. Phoenixin: uncovering its receptor, signaling and functions. Acta Pharmacol Sin 2018; 39:774-778. [PMID: 29671415 PMCID: PMC5943909 DOI: 10.1038/aps.2018.13] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 02/28/2018] [Indexed: 12/12/2022] Open
Abstract
Phoenixin (PNX) is a newly discovered peptide that has been linked to reproductive function, both in the hypothalamus and pituitary. This review will focus on the most recent discoveries related to this novel neuropeptide. Initially, it was found that PNX increased gonadotropin releasing hormone (GnRH)-stimulated luteinizing hormone (LH) release from pituitary cells. Importantly, knockdown of PNX in female rats extended the estrous cycle by 2.3 days. Using novel hypothalamic cell lines, we found that PNX has a stimulatory role on kisspeptin (Kiss) and GnRH gene expression and secretion. The PNX receptor was uncovered using siRNA knockdown of GPR173, an orphan receptor postulated to bind PNX. We have found that the PNX-R signaling through protein kinase A (PKA) in hypothalamic neurons. Althuogh a number of studies demonstrate that PNX plays an important role in reproductive function, there is also evidence that it may have other functions, regulating the heart, feeding, memory, and anxiety, both in the brain and the periphery.
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Affiliation(s)
| | - Denise D Belsham
- Departments of Physiology
- Obstetrics and Gynaecology and Medicine, University of Toronto, Toronto, ON, Canada
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12
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Treen AK, Luo V, Belsham DD. Phoenixin Activates Immortalized GnRH and Kisspeptin Neurons Through the Novel Receptor GPR173. Mol Endocrinol 2016; 30:872-88. [PMID: 27268078 DOI: 10.1210/me.2016-1039] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Reproductive function is coordinated by kisspeptin (Kiss) and GnRH neurons. Phoenixin-20 amide (PNX) is a recently described peptide found to increase GnRH-stimulated LH secretion in the pituitary. However, the effects of PNX in the hypothalamus, the putative signaling pathways, and PNX receptor have yet to be identified. The mHypoA-GnRH/GFP and mHypoA-Kiss/GFP-3 cell lines represent populations of GnRH and Kiss neurons, respectively. PNX increased GnRH and GnRH receptor (GnRH-R) mRNA expression, as well as GnRH secretion, in the mHypoA-GnRH/GFP cell model. In the mHypoA-Kiss/GFP-3 cell line, PNX increased Kiss1 mRNA expression. CCAAT/enhancer-binding protein (C/EBP)-β, octamer transcription factor-1 (Oct-1), and cAMP response element binding protein (CREB) binding sites are localized to the 5' flanking regions of the GnRH, GnRH-R, and Kiss1 genes. PNX decreased C/EBP-β mRNA expression in both cell models and increased Oct-1 mRNA expression in the mHypoA-GnRH/GFP neurons. PNX increased CREB phosphorylation in both cell models and phospho-ERK1/2 in the mHypoA-GnRH/GFP cell model, whereas inhibiting the cAMP/protein kinase A pathway prevented PNX induction of GnRH and Kiss1 mRNA expression. Importantly, we determined that the G protein-coupled receptor, GPR173, was strongly expressed in both GnRH and kisspeptin cell models and small interfering RNA knockdown of GPR173 prevented the PNX-mediated up-regulation of GnRH, GnRH-R, and Kiss1 mRNA expression and the down-regulation of C/EBP-β mRNA expression. PNX also increased GPR173 mRNA expression in the mHypoA-GnRH/GFP cells. Taken together, these studies are the first to implicate that PNX acts through GPR173 to activate the cAMP/protein kinase A pathway through CREB, and potentially C/EBP-β and/or Oct-1 to increase GnRH, GnRH-R, and Kiss1 gene expression, ultimately having a stimulatory effect on reproductive function.
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Affiliation(s)
- Alice K Treen
- Departments of Physiology (A.K.T., V.L., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Vicky Luo
- Departments of Physiology (A.K.T., V.L., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Denise D Belsham
- Departments of Physiology (A.K.T., V.L., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
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13
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Tran DQ, Ramos EH, Belsham DD. Induction of Gnrh mRNA expression by the ω-3 polyunsaturated fatty acid docosahexaenoic acid and the saturated fatty acid palmitate in a GnRH-synthesizing neuronal cell model, mHypoA-GnRH/GFP. Mol Cell Endocrinol 2016; 426:125-35. [PMID: 26923440 DOI: 10.1016/j.mce.2016.02.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 02/22/2016] [Accepted: 02/22/2016] [Indexed: 12/18/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons coordinate reproduction. However, whether GnRH neurons directly sense free fatty acids (FFAs) is unknown. We investigated the individual effects of the FFAs docosahexaenoic acid (DHA), palmitate, palmitoleate, and oleate (100 μM each) on Gnrh mRNA expression in the mHypoA-GnRH/GFP neuronal cell model. We report that 2 h exposure to palmitate or DHA increases Gnrh transcription. Using the inhibitors AH7614, K252c, U0126, wortmannin, and LY294002, we demonstrate that the effect of DHA is mediated through GPR120 to downstream PKC/MAPK and PI3K signaling. Our results indicate that the effect of palmitate may depend on palmitoyl-coA synthesis and PI3K signaling. Finally, we demonstrate that both DHA and palmitate increase Gnrh enhancer-derived RNA levels. Overall, these studies provide evidence that GnRH neurons directly sense FFAs. This will advance our understanding of the mechanisms underlying FFA sensing in the brain and provides insight into the links between nutrition and reproductive function.
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Affiliation(s)
- Dean Q Tran
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Ernesto H Ramos
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Denise D Belsham
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Obstetrics and Gynaecology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.
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14
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Treen AK, Luo V, Chalmers JA, Dalvi PS, Tran D, Ye W, Kim GL, Friedman Z, Belsham DD. Divergent Regulation of ER and Kiss Genes by 17β-Estradiol in Hypothalamic ARC Versus AVPV Models. Mol Endocrinol 2016; 30:217-33. [PMID: 26726951 DOI: 10.1210/me.2015-1189] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Kisspeptin (Kiss) and G-protein-coupled receptor (Gpr)54 have emerged as key regulators of reproduction. 17β-estradiol (E2)-mediated regulation of these neurons is nuclei specific, where anteroventral periventricular (AVPV) Kiss neurons are positively regulated by E2, whereas arcuate nucleus (ARC) neurons are inhibited. We have generated immortalized Kiss cell lines from male and female adult-derived murine hypothalamic primary culture, as well as cell lines from microdissected AVPV and ARC from female Kiss-green fluorescent protein (GFP) mice. All exhibit endogenous Kiss-1 expression, estrogen receptors (ER)s (ERα, ERβ, and Gpr30), as well as known markers of AVPV Kiss neurons in the mHypoA-50 and mHypoA-Kiss/GFP-4, vs markers of ARC Kiss neurons in the mHypoA-55 and the mHypoA-Kiss/GFP-3 lines. There was an increase in Kiss-1 mRNA expression at 24 hours in the AVPV lines and a repression of Kiss-1 mRNA at 4 hours in the ARC lines. An E2-mediated decrease in ERα mRNA expression at 24 hours in the AVPV cell lines was detected, and a significant decrease in Gpr30, ERα, and ERβ mRNA levels at 4 hours in the ARC cell lines was evident. ER agonists and antagonists determined the specific ERs responsible for mediating changes in gene expression. In the AVPV, ERα is required but not ERβ or GPR30, vs the ARC Kiss-expressing cell lines that require GPR30, and either ERα and/or ERβ. We determined cAMP response element-binding protein 1 was necessary for the down-regulation of Kiss-1 mRNA expression using small interfering RNA knockdown in the ARC cell model. These studies elucidate some of the molecular events involved in the differential E2-mediated regulation of unique and specific Kiss neuronal models.
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Affiliation(s)
- Alice K Treen
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Vicky Luo
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Jennifer A Chalmers
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Prasad S Dalvi
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Dean Tran
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Wenqing Ye
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Ginah L Kim
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Zoey Friedman
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
| | - Denise D Belsham
- Departments of Physiology (A.K.T., V.L., J.A.C., P.S.D., D.T., W.Y., G.L.K., Z.F., D.D.B.), Medicine (D.D.B.), and Obstetrics and Gynaecology (D.D.B.), University of Toronto, and Division of Cellular and Molecular Biology (D.D.B.), Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada M5S 1A8
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15
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Wellhauser L, Gojska NM, Belsham DD. Delineating the regulation of energy homeostasis using hypothalamic cell models. Front Neuroendocrinol 2015; 36:130-49. [PMID: 25223866 DOI: 10.1016/j.yfrne.2014.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/28/2014] [Accepted: 09/02/2014] [Indexed: 12/27/2022]
Abstract
Attesting to its intimate peripheral connections, hypothalamic neurons integrate nutritional and hormonal cues to effectively manage energy homeostasis according to the overall status of the system. Extensive progress in the identification of essential transcriptional and post-translational mechanisms regulating the controlled expression and actions of hypothalamic neuropeptides has been identified through the use of animal and cell models. This review will introduce the basic techniques of hypothalamic investigation both in vivo and in vitro and will briefly highlight the key advantages and challenges of their use. Further emphasis will be place on the use of immortalized models of hypothalamic neurons for in vitro study of feeding regulation, with a particular focus on cell lines proving themselves most fruitful in deciphering fundamental basics of NPY/AgRP, Proglucagon, and POMC neuropeptide function.
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Affiliation(s)
- Leigh Wellhauser
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Nicole M Gojska
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Denise D Belsham
- Departments of Physiology, Medicine and OB/GYN, University of Toronto, Toronto, Ontario M5G 1A8, Canada; Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario M5S 1A8, Canada.
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16
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Gojska NM, Friedman Z, Belsham DD. Direct regulation of gonadotrophin-releasing hormone (GnRH) transcription by RF-amide-related peptide-3 and kisspeptin in a novel GnRH-secreting cell line, mHypoA-GnRH/GFP. J Neuroendocrinol 2014; 26:888-97. [PMID: 25283492 DOI: 10.1111/jne.12225] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/09/2014] [Accepted: 09/24/2014] [Indexed: 11/30/2022]
Abstract
RF-amide-related peptide-3 [RFRP-3; also often referred to as the mammalian orthologue of the avian gonadotrophin-inhibitory hormone (GnIH)] and kisspeptin have emerged as potent modulators of neuroendocrine function via direct regulation of the reproductive axis in the hypothalamus and pituitary. There are few studies focusing on the direct regulatory effects of RFRP-3 and kisspeptin on gonadotrophin-releasing hormones (GnRH) neurones. We report their effect on GnRH mRNA expression and release in a novel GnRH neuronal cell model, mHypoA-GnRH/GFP, generated from adult-derived GnRH-GFP neurones. The neurones express receptors for both RFRP-3 and kisspeptin, Gpr147 and Gpr54, respectively. Incubation with 100 nm RFRP-3 results in attenuation of GnRH mRNA expression by approximately 60%. Conversely, incubation with 10 nm of Kiss-10 induced GnRH mRNA expression, whereas the combined effect was an overall repression of GnRH mRNA levels. With transcription inhibitors, the repression of GnRH mRNA levels was linked to a transcriptional mechanism but not mRNA stability. No significant changes in GnRH secretion were observed upon RFRP-3 exposure in these neurones. Our findings suggest that the suppressive signalling of RFRP-3 on GnRH transcription may dominate over kisspeptin induction in the mHypoA-GnRH/GFP GnRH neuronal cell model.
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Affiliation(s)
- N M Gojska
- Department of Physiology, University of Toronto, Toronto, ON, Canada
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17
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Xu Q, Liu X, Zheng X, Yao Y, Wang M, Liu Q. The transcriptional activity of Gli1 is negatively regulated by AMPK through Hedgehog partial agonism in hepatocellular carcinoma. Int J Mol Med 2014; 34:733-41. [PMID: 25017332 PMCID: PMC4121351 DOI: 10.3892/ijmm.2014.1847] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 07/03/2014] [Indexed: 01/08/2023] Open
Abstract
The aberrant activation of the Hedgehog (Hh) signaling pathway has been implicated in a variety of malignancies, including hepatocellular carcinoma (HCC). The mammalian 5' adenosine monophosphate-activated protein kinase (AMPK) plays a crucial role in cellular energy homeostasis. However, the interaction between the Hh and AMPK signaling pathways has not been investigated to date. In the present study, to the best of our knowlege, we report for the first time the negative regulation of glioma-associated oncogene 1 (Gli1), an important downstream effector of Hh, by the AMPK signal transduction pathway. Immunoprecipitation and GST-pull down assay showed a direct interaction between AMPK and Gli1. The overexpression of AMPK induced the downregulation of Gli1 expression, while the knockdown of AMPK upregulated Gli1 expression in a relatively short period of time (24 h or less). Our data suggest that AMPK may function as an upstream molecule that regulates Gli1 expression. Therefore, AMPK may play a role in the Hh signaling pathway, through which it regulates tumorigenesis.
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Affiliation(s)
- Qiuran Xu
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Xin Liu
- Department of Neurosurgery, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Xin Zheng
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yingmin Yao
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Maode Wang
- Department of Neurosurgery, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Qingguang Liu
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
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18
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Xu Q, Yang C, Du Y, Chen Y, Liu H, Deng M, Zhang H, Zhang L, Liu T, Liu Q, Wang L, Lou Z, Pei H. AMPK regulates histone H2B O-GlcNAcylation. Nucleic Acids Res 2014; 42:5594-604. [PMID: 24692660 PMCID: PMC4027166 DOI: 10.1093/nar/gku236] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Histone H2B O-GlcNAcylation is an important post-translational modification of chromatin during gene transcription. However, how this epigenetic modification is regulated remains unclear. Here we found that the energy-sensing adenosine-monophosphate-activated protein kinase (AMPK) could suppress histone H2B O-GlcNAcylation. AMPK directly phosphorylates O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT). Although this phosphorylation does not regulate the enzymatic activity of OGT, it inhibits OGT-chromatin association, histone O-GlcNAcylation and gene transcription. Conversely, OGT also O-GlcNAcylates AMPK and positively regulates AMPK activity, creating a feedback loop. Taken together, these results reveal a crosstalk between the LKB1-AMPK and the hexosamine biosynthesis (HBP)-OGT pathways, which coordinate together for the sensing of nutrient state and regulation of gene transcription.
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Affiliation(s)
- Qiuran Xu
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China
| | - Caihong Yang
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yu Du
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Yali Chen
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Hailong Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Min Deng
- Division of Oncology Research, Mayo Clinic, Rochester, MN 55905, USA
| | - Haoxing Zhang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China Division of Oncology Research, Mayo Clinic, Rochester, MN 55905, USA
| | - Lei Zhang
- Division of Oncology Research, Mayo Clinic, Rochester, MN 55905, USA
| | - Tongzheng Liu
- Division of Oncology Research, Mayo Clinic, Rochester, MN 55905, USA
| | - Qingguang Liu
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China
| | - Liewei Wang
- Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA
| | - Zhenkun Lou
- Division of Oncology Research, Mayo Clinic, Rochester, MN 55905, USA
| | - Huadong Pei
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
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19
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Morelli A, Comeglio P, Sarchielli E, Cellai I, Vignozzi L, Vannelli GB, Maggi M. Negative effects of high glucose exposure in human gonadotropin-releasing hormone neurons. Int J Endocrinol 2013; 2013:684659. [PMID: 24489542 PMCID: PMC3893744 DOI: 10.1155/2013/684659] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 12/13/2013] [Accepted: 12/18/2013] [Indexed: 01/01/2023] Open
Abstract
Metabolic disorders are often associated with male hypogonadotropic hypogonadism, suggesting that hypothalamic defects involving GnRH neurons may impair the reproductive function. Among metabolic factors hyperglycemia has been implicated in the control of the reproductive axis at central level, both in humans and in animal models. To date, little is known about the direct effects of pathological high glucose concentrations on human GnRH neurons. In this study, we investigated the high glucose effects in the human GnRH-secreting FNC-B4 cells. Gene expression profiling by qRT-PCR, confirmed that FNC-B4 cells express GnRH and several genes relevant for GnRH neuron function (KISS1R, KISS1, sex steroid and leptin receptors, FGFR1, neuropilin 2, and semaphorins), along with glucose transporters (GLUT1, GLUT3, and GLUT4). High glucose exposure (22 mM; 40 mM) significantly reduced gene and protein expression of GnRH, KISS1R, KISS1, and leptin receptor, as compared to normal glucose (5 mM). Consistent with previous studies, leptin treatment significantly induced GnRH mRNA expression at 5 mM glucose, but not in the presence of high glucose concentrations. In conclusion, our findings demonstrate a deleterious direct contribution of high glucose on human GnRH neurons, thus providing new insights into pathogenic mechanisms linking metabolic disorders to reproductive dysfunctions.
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Affiliation(s)
- Annamaria Morelli
- Section of Anatomy and Histology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Paolo Comeglio
- Section of Sexual Medicine and Andrology, Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
| | - Erica Sarchielli
- Section of Anatomy and Histology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Ilaria Cellai
- Section of Sexual Medicine and Andrology, Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
| | - Linda Vignozzi
- Section of Sexual Medicine and Andrology, Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
| | - Gabriella B. Vannelli
- Section of Anatomy and Histology, Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Mario Maggi
- Section of Sexual Medicine and Andrology, Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
- Centro Interuniversitario di Ricerca sulle Basi Molecolari della Malattie della Riproduzione (CIRMAR), 20122 Milan, Italy
- *Mario Maggi:
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