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Zhou YS, Tao HB, Lv SS, Liang KQ, Shi WY, Liu KY, Li YY, Chen LY, Zhou L, Yin SJ, Zhao QR. Effects of Kv1.3 knockout on pyramidal neuron excitability and synaptic plasticity in piriform cortex of mice. Acta Pharmacol Sin 2024:10.1038/s41401-024-01275-y. [PMID: 38862816 DOI: 10.1038/s41401-024-01275-y] [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: 08/13/2023] [Accepted: 03/24/2024] [Indexed: 06/13/2024] Open
Abstract
Kv1.3 belongs to the voltage-gated potassium (Kv) channel family, which is widely expressed in the central nervous system and associated with a variety of neuropsychiatric disorders. Kv1.3 is highly expressed in the olfactory bulb and piriform cortex and involved in the process of odor perception and nutrient metabolism in animals. Previous studies have explored the function of Kv1.3 in olfactory bulb, while the role of Kv1.3 in piriform cortex was less known. In this study, we investigated the neuronal changes of piriform cortex and feeding behavior after smell stimulation, thus revealing a link between the olfactory sensation and body weight in Kv1.3 KO mice. Coronal slices including the anterior piriform cortex were prepared, whole-cell recording and Ca2+ imaging of pyramidal neurons were conducted. We showed that the firing frequency evoked by depolarization pulses and Ca2+ influx evoked by high K+ solution were significantly increased in pyramidal neurons of Kv1.3 knockout (KO) mice compared to WT mice. Western blotting and immunofluorescence analyses revealed that the downstream signaling molecules CaMKII and PKCα were activated in piriform cortex of Kv1.3 KO mice. Pyramidal neurons in Kv1.3 KO mice exhibited significantly reduced paired-pulse ratio and increased presynaptic Cav2.1 expression, proving that the presynaptic vesicle release might be elevated by Ca2+ influx. Using Golgi staining, we found significantly increased dendritic spine density of pyramidal neurons in Kv1.3 KO mice, supporting the stronger postsynaptic responses in these neurons. In olfactory recognition and feeding behavior tests, we showed that Kv1.3 conditional knockout or cannula injection of 5-(4-phenoxybutoxy) psoralen, a Kv1.3 channel blocker, in piriform cortex both elevated the olfactory recognition index and altered the feeding behavior in mice. In summary, Kv1.3 is a key molecule in regulating neuronal activity of the piriform cortex, which may lay a foundation for the treatment of diseases related to piriform cortex and olfactory detection.
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Affiliation(s)
- Yong-Sheng Zhou
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Hao-Bo Tao
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Si-Si Lv
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Ke-Qin Liang
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Wen-Yi Shi
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Ke-Yi Liu
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Yun-Yun Li
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Lv-Yi Chen
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Ling Zhou
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China
| | - Shi-Jin Yin
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China.
| | - Qian-Ru Zhao
- Department of Chemical Biology, School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, 430074, China.
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2
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Stark R. The olfactory bulb: A neuroendocrine spotlight on feeding and metabolism. J Neuroendocrinol 2024; 36:e13382. [PMID: 38468186 DOI: 10.1111/jne.13382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/22/2024] [Accepted: 02/25/2024] [Indexed: 03/13/2024]
Abstract
Olfaction is the most ancient sense and is needed for food-seeking, danger protection, mating and survival. It is often the first sensory modality to perceive changes in the external environment, before sight, taste or sound. Odour molecules activate olfactory sensory neurons that reside on the olfactory epithelium in the nasal cavity, which transmits this odour-specific information to the olfactory bulb (OB), where it is relayed to higher brain regions involved in olfactory perception and behaviour. Besides odour processing, recent studies suggest that the OB extends its function into the regulation of food intake and energy balance. Furthermore, numerous hormone receptors associated with appetite and metabolism are expressed within the OB, suggesting a neuroendocrine role outside the hypothalamus. Olfactory cues are important to promote food preparatory behaviours and consumption, such as enhancing appetite and salivation. In addition, altered metabolism or energy state (fasting, satiety and overnutrition) can change olfactory processing and perception. Similarly, various animal models and human pathologies indicate a strong link between olfactory impairment and metabolic dysfunction. Therefore, understanding the nature of this reciprocal relationship is critical to understand how olfactory or metabolic disorders arise. This present review elaborates on the connection between olfaction, feeding behaviour and metabolism and will shed light on the neuroendocrine role of the OB as an interface between the external and internal environments. Elucidating the specific mechanisms by which olfactory signals are integrated and translated into metabolic responses holds promise for the development of targeted therapeutic strategies and interventions aimed at modulating appetite and promoting metabolic health.
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Affiliation(s)
- Romana Stark
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, Australia
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3
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Cheng S, Jiang D, Lan X, Liu K, Fan C. Voltage-gated potassium channel 1.3: A promising molecular target in multiple disease therapy. Biomed Pharmacother 2024; 175:116651. [PMID: 38692062 DOI: 10.1016/j.biopha.2024.116651] [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: 02/20/2024] [Revised: 04/21/2024] [Accepted: 04/24/2024] [Indexed: 05/03/2024] Open
Abstract
Voltage-gated potassium channel 1.3 (Kv1.3) has emerged as a pivotal player in numerous biological processes and pathological conditions, sparking considerable interest as a potential therapeutic target across various diseases. In this review, we present a comprehensive examination of Kv1.3 channels, highlighting their fundamental characteristics and recent advancements in utilizing Kv1.3 inhibitors for treating autoimmune disorders, neuroinflammation, and cancers. Notably, Kv1.3 is prominently expressed in immune cells and implicated in immune responses and inflammation associated with autoimmune diseases and chronic inflammatory conditions. Moreover, its aberrant expression in certain tumors underscores its role in cancer progression. While preclinical studies have demonstrated the efficacy of Kv1.3 inhibitors, their clinical translation remains pending. Molecular imaging techniques offer promising avenues for tracking Kv1.3 inhibitors and assessing their therapeutic efficacy, thereby facilitating their development and clinical application. Challenges and future directions in Kv1.3 inhibitor research are also discussed, emphasizing the significant potential of targeting Kv1.3 as a promising therapeutic strategy across a spectrum of diseases.
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Affiliation(s)
- Sixuan Cheng
- Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Hubei Key Laboratory of Molecular Imaging, Wuhan 430022, China
| | - Dawei Jiang
- Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Hubei Key Laboratory of Molecular Imaging, Wuhan 430022, China
| | - Xiaoli Lan
- Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Hubei Key Laboratory of Molecular Imaging, Wuhan 430022, China
| | - Kun Liu
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Cheng Fan
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
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4
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Wang H, Jayasankar N, Thamaraikani T, Viktor P, Mohany M, Al-Rejaie SS, Alammar HK, Anad E, Alhili F, Hussein SF, Amin AH, Lakshmaiya N, Ahsan M, Bahrami A, Akhavan-Sigari R. Quercetin modulates expression of serum exosomal long noncoding RNA NEAT1 to regulate the miR-129-5p/BDNF axis and attenuate cognitive impairment in diabetic mice. Life Sci 2024; 340:122449. [PMID: 38253310 DOI: 10.1016/j.lfs.2024.122449] [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: 10/24/2023] [Revised: 01/08/2024] [Accepted: 01/17/2024] [Indexed: 01/24/2024]
Abstract
AIMS Cognitive impairment poses a considerable health challenge in the context of type 2 diabetes mellitus (T2DM), emphasizing the need for effective interventions. This study delves into the therapeutic efficacy of quercetin, a natural flavonoid, in mitigating cognitive impairment induced by T2DM in murine models. MATERIALS AND METHODS Serum exosome samples were obtained from both T2DM-related and healthy mice for transcriptome sequencing, enabling the identification of differentially expressed mRNAs and long noncoding RNAs (lncRNAs). Subsequent experiments were conducted to ascertain the binding affinity between mmu-miR-129-5p, NEAT1 and BDNF. The structural characteristics and dimensions of isolated exosomes were scrutinized, and the expression levels of exosome-associated proteins were quantified. Primary mouse hippocampal neurons were cultured for in vitro validation, assessing the expression of pertinent genes as well as neuronal vitality, proliferation, and apoptosis capabilities. For in vivo validation, a T2DM mouse model was established, and quercetin treatment was administered. Changes in various parameters, cognitive ability, and the expression of insulin-related proteins, along with pivotal signaling pathways, were monitored. KEY FINDINGS Analysis of serum exosomes from T2DM mice revealed dysregulation of NEAT1, mmu-miR-129-5p, and BDNF. In vitro investigations demonstrated that NEAT1 upregulated BDNF expression by inhibiting mmu-miR-129-5p. Overexpression of mmu-miR-129-5p or silencing NEAT1 resulted in the downregulation of insulin-related protein expression, enhanced apoptosis, and suppressed neuronal proliferation. In vivo studies validated that quercetin treatment significantly ameliorated T2DM-related cognitive impairment in mice. SIGNIFICANCE These findings suggest that quercetin holds promise in inhibiting hippocampal neuron apoptosis and improving T2DM-related cognitive impairment by modulating the NEAT1/miR-129-5p/BDNF pathway within serum exosomes.
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Affiliation(s)
- Hui Wang
- Department of Plastic Surgery, The Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu 322000, China
| | - Narayanan Jayasankar
- Department of Pharmacology, SRM Institute of Science and Technology, SRM College of Pharmacy, Kattankulathur 603203, Tamil Nadu, India
| | - Tamilanban Thamaraikani
- Department of Pharmacology, SRM Institute of Science and Technology, SRM College of Pharmacy, Kattankulathur 603203, Tamil Nadu, India
| | - Patrik Viktor
- Keleti Károly Faculty of Business and Management, Óbuda University, Tavaszmező, H-1084 Budapest, Hungary
| | - Mohamed Mohany
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Salim S Al-Rejaie
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | | | - Enaam Anad
- Department of Medical Laboratory Technics, Al-Noor University College, Nineveh, Iraq
| | - Farah Alhili
- Medical Technical College, Al-Farahidi University, Iraq
| | - Sinan F Hussein
- Department of Pharmacy, Al-Zahrawi University College, Karbala, Iraq
| | - Ali H Amin
- Zoology Department, Faculty of Science, Mansoura University, Mansoura 35516, Egypt
| | - Natrayan Lakshmaiya
- Department of Mechanical Engineering, Saveetha School of Engineering, SIMATS, Chennai, Tamil Nadu, India
| | - Muhammad Ahsan
- Department of Measurements and Control Systems, Silesian University of Technology, Gliwice, Poland; Joint Doctoral School, Silesian University of Technology, Akademicka 2A, Gliwice, Poland.
| | - Abolfazl Bahrami
- Biomedical Center for Systems Biology Science Munich, Ludwig-Maximilians-University, Munich, Germany.
| | - Reza Akhavan-Sigari
- Department of Health Care Management and Clinical Research, Collegium Humanum Warsaw, Poland; Department of Neurosurgery, University Medical Center Tuebingen, Germany
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5
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Dai Q, Du Z, Jing L, Zhang R, Tang W. Enzyme-Responsive Modular Peptides Enhance Tumor Penetration of Quantum Dots via Charge Reversal Strategy. ACS APPLIED MATERIALS & INTERFACES 2024; 16:6208-6220. [PMID: 38279946 DOI: 10.1021/acsami.3c11500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2024]
Abstract
Quantum dots (QDs) are colloidal semiconductor nanoparticles acting as fluorescent probes for detection, disease diagnosis, and photothermal and photodynamic therapy. However, their performance in cancer treatment is limited by inadequate tumor accumulation and penetration due to the larger size of nanoparticles compared to small molecules. To address this challenge, charge reversal nanoparticles offer an effective strategy to prolong blood circulation time and achieve enhanced endocytosis and tumor penetration. In this study, we leveraged the overexpressed γ-glutamyl transpeptidase (GGT) in many human tumors and developed a library of modular peptides to serve as water-soluble surface ligands of QDs. We successfully transferred the QDs from the organic phase to the aqueous phase within 5 min. And through systematic tuning of the peptide sequence, we optimized the fluorescent stability of QDs and their charge reversal behavior in response to GGT. The resulting optimal peptide stabilized QDs in aqueous solution with a high fluorescent retention rate of 93% after three months and realized the surface charge reversal of QDs triggered by GGT in vitro. The binding between the peptide and QD surface was investigated by using saturation transfer differential nuclear magnetic resonance (STD NMR). Thanks to its charge reversal ability, the GGT-responsive QDs exhibited enhanced cellular uptake in GGT-expressing cancer cells and deeper penetration in the 3D multicellular spheroids. This enzyme-responsive modular peptide can lead to specific tumor targeting and deeper tumor penetration, holding great promise to enhance the treatment efficacy of QD-based theranostics.
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Affiliation(s)
- Qiuju Dai
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Zhen Du
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Lihong Jing
- Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Bei Yi Jie 2, Zhong Guan Cun, Beijing 100190, China
| | - Rongchun Zhang
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Wen Tang
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
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6
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Sun HZ, Shen FS, Li XX, Liu C, Xue Y, Han XH, Chen XY, Chen L. Exendin-4 increases the firing activity of hippocampal CA1 neurons through TRPC4/5 channels. Neurosci Res 2024; 199:48-56. [PMID: 37595875 DOI: 10.1016/j.neures.2023.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 07/24/2023] [Accepted: 08/15/2023] [Indexed: 08/20/2023]
Abstract
The central neuropeptide GLP-1 is synthesized by preproglucagon (PPG) neurons in the brain. GLP-1 receptors are widely distributed in central nervous system. Hippocampus is a key component of the limbic system which is involved in learning, memory, and cognition. Previous studies have shown that overexpression of GLP-1 receptors in the hippocampus could improve the process of learning and memory. However, up to now, the direct electrophysiological effects and possible molecular mechanisms of GLP-1 in hippocampal CAl neurons remain unexplored. The present study aims to evaluate the effects and mechanisms of GLP-1 on the spontaneous firing activity of hippocampal CAl neurons. Employing multibarrel single-unit extracellular recordings, the present study showed that micro-pressure administration of GLP-1 receptor agonist, exendin-4, significantly increased the spontaneous firing rate of hippocampal CA1 neurons in rats. Furthermore, application of the specific GLP-1 receptor antagonist, exendin(9-39), alone significantly decreased the firing rate of CA1 neurons, suggesting that endogenous GLP-1 modulates the firing activity of CA1 neurons. Co-application of exendin(9-39) completely blocked exendin-4-induced excitation of hippocampal CA1 neurons. Finally, the present study demonstrated for the first time that the transient receptor potential canonical 4 (TRPC4)/TRPC5 channels may be involved in exendin-4-induced excitation. The present studies may provide a rationale for further investigation of the modulation of GLP-1 on learning and memory as well as its possible involvement in Alzheimer's disease.
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Affiliation(s)
- Hui-Zhe Sun
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Fang-Shuai Shen
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Xiao-Xue Li
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Cui Liu
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Yan Xue
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Xiao-Hua Han
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Xin-Yi Chen
- Department of International Medicine, Affiliated Hospital of Qingdao University, Qingdao, China.
| | - Lei Chen
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China.
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7
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Wang XY, Liu Y, Cao LX, Li YZ, Wan P, Qiu DL. Glucagon-like peptide-1 facilitates cerebellar parallel fiber glutamate release through PKA signaling in mice in vitro. Sci Rep 2023; 13:7948. [PMID: 37193712 DOI: 10.1038/s41598-023-34070-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 04/24/2023] [Indexed: 05/18/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is mainly secreted by preproglucagon neurons; it plays important roles in modulating neuronal activity and synaptic transmission through its receptors. In the present study, we investigated the effects of GLP-1 on parallel fiber-Purkinje cell (PF-PC) synaptic transmission in mouse cerebellar slices using whole-cell patch-clamp recording and pharmacology methods. In the presence of a γ-aminobutyric acid type A receptor antagonist, bath application of GLP-1 (100 nM) enhanced PF-PC synaptic transmission, with an increased amplitude of evoked excitatory postsynaptic synaptic currents (EPSCs) and a decreased paired-pulse ratio. The GLP-1-induced enhancement of evoked EPSCs was abolished by a selective GLP-1 receptor antagonist, exendin 9-39, as well as by the extracellular application of a specific protein kinase A (PKA) inhibitor, KT5720. In contrast, inhibiting postsynaptic PKA with a protein kinase inhibitor peptide-containing internal solution failed to block the GLP-1-induced enhancement of evoked EPSCs. In the presence of a mixture of gabazine (20 μM) and tetrodotoxin (1 μM), application GLP-1 significantly increased frequency, but not amplitude of miniature EPSCs via PKA signaling pathway. The GLP-1-induced increase in miniature EPSC frequency was blocked by both exendin 9-39 and KT5720. Together, our results indicate that GLP-1 receptor activation enhances glutamate release at PF-PC synapses via the PKA signaling pathway, resulting in enhanced PF-PC synaptic transmission in mice in vitro. These findings suggest that, in living animals, GLP-1 has a critical role in the modulation of cerebellar function by regulating excitatory synaptic transmission at PF-PC synapses.
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Affiliation(s)
- Xin-Yuan Wang
- Department of Neurology, Affiliated Hospital of Yanbian University, Yanji, 133000, Jilin, China
| | - Yang Liu
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, 132013, Jilin, China
| | - Li-Xin Cao
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, 133000, Jilin, China
| | - Yu-Zi Li
- Department of Cardiology, Affiliated Hospital of Yanbian University, Yanji, 133000, Jilin, China
| | - Peng Wan
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, 132013, Jilin, China.
| | - De-Lai Qiu
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, 132013, Jilin, China.
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8
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Wang Y, Hurley A, De Giorgi M, Tanner MR, Hu RC, Pennington MW, Lagor WR, Beeton C. Adeno-Associated virus 8 delivers an immunomodulatory peptide to mouse liver more efficiently than to rat liver. PLoS One 2023; 18:e0283996. [PMID: 37040361 PMCID: PMC10089316 DOI: 10.1371/journal.pone.0283996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 03/21/2023] [Indexed: 04/12/2023] Open
Abstract
Targeting the Kv1.3 potassium channel has proven effective in reducing obesity and the severity of animal models of autoimmune disease. Stichodactyla toxin (ShK), isolated from the sea anemone Stichodactyla helianthus, is a potent blocker of Kv1.3. Several of its analogs are some of the most potent and selective blockers of this channel. However, like most biologics, ShK and its analogs require injections for their delivery, and repeated injections reduce patient compliance during the treatment of chronic diseases. We hypothesized that inducing the expression of an ShK analog by hepatocytes would remove the requirement for frequent injections and lead to a sustained level of Kv1.3 blocker in the circulation. To this goal, we tested the ability of Adeno-Associated Virus (AAV)8 vectors to target hepatocytes for expressing the ShK analog, ShK-235 (AAV-ShK-235) in rodents. We designed AAV8 vectors expressing the target transgene, ShK-235, or Enhanced Green fluorescent protein (EGFP). Transduction of mouse livers led to the production of sufficient levels of functional ShK-235 in the serum from AAV-ShK-235 single-injected mice to block Kv1.3 channels. However, AAV-ShK-235 therapy was not effective in reducing high-fat diet-induced obesity in mice. In addition, injection of even high doses of AAV8-ShK-235 to rats resulted in a very low liver transduction efficiency and failed to reduce inflammation in a well-established rat model of delayed-type hypersensitivity. In conclusion, the AAV8-based delivery of ShK-235 was highly effective in inducing the secretion of functional Kv1.3-blocking peptide in mouse, but not rat, hepatocytes yet did not reduce obesity in mice fed a high-fat diet.
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Affiliation(s)
- Yuqing Wang
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ayrea Hurley
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Marco De Giorgi
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mark R. Tanner
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Rong-Chi Hu
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States of America
| | | | - William R. Lagor
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Christine Beeton
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States of America
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9
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Liu Y, Cao LX, Wang WY, Piao YR, Wang JY, Chu CP, Bing YH, Qiu DL. GLP-1 enhances hyperpolarization-activated currents of mouse cerebellar Purkinje cell in vitro. Front Mol Neurosci 2023; 16:1126447. [PMID: 37089690 PMCID: PMC10113493 DOI: 10.3389/fnmol.2023.1126447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 03/16/2023] [Indexed: 04/08/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is mainly secreted by preglucagonergic neurons in the nucleus tractus solitarius, which plays critical roles in regulation of neuronal activity in the central nervous system through its receptor. In the cerebellar cortex, GLP-1 receptor is abundantly expressed in the molecular layer, Purkinje cell (PC) layer and granular layer, indicating that GLP-1 may modulate the cerebellar neuronal activity. In this study, we investigated the mechanism by which GLP1 modulates mouse cerebellar PC activity in vitro. After blockade of glutamatergic and GABAergic synaptic transmission in PCs, GLP1 increased the spike firing rate accompanied by depolarization of membrane potential and significantly depressed the after-hyperpolarizing potential and outward rectifying current of spike firing discharges via GLP1 receptors. In the presence of TTX and Ba2+, GLP1 significantly enhanced the hyperpolarized membrane potential-evoked instant current, steady current, tail current (I-tail) and hyperpolarization-activated (IH) current. Application of a selective IH channel antagonist, ZD7288, blocked IH and abolished the effect of GLP1 on PC membrane currents. The GLP1 induced enhancement of membrane currents was also abolished by a selective GLP1 receptor antagonist, exendin-9-39, as well as by protein kinase A (PKA) inhibitors, KT5720 and H89. In addition, immunofluorescence detected GLP1 receptor in the mouse cerebellar cortex, mostly in PCs. These results indicated that GLP1 receptor activation enhanced IH channel activity via PKA signaling, resulting in increased excitability of mouse cerebellar PCs in vitro. The present findings indicate that GLP1 plays a critical role in modulating cerebellar function by regulating the spike firing activity of mouse cerebellar PCs.
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Affiliation(s)
- Yang Liu
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin, China
| | - Li-Xin Cao
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin, China
| | - Wei-Yao Wang
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, Jilin, China
| | - Yong-Rui Piao
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin, China
- Department of Urology, Affiliated Hospital of Yanbian University, Yanji, Jilin, China
| | - Jun-Ya Wang
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin, China
| | - Chun-Ping Chu
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, Jilin, China
| | - Yan-Hua Bing
- Functional Experiment Center, College of Medicine, Yanbian University, Yanji, Jilin, China
- *Correspondence: Yan-Hua Bing,
| | - De-Lai Qiu
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin, China
- Department of Physiology, College of Basic Medicine, Jilin Medical University, Jilin, Jilin, China
- De-Lai Qiu, ;
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10
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Tsuneki H, Sugiyama M, Ito T, Sato K, Matsuda H, Onishi K, Yubune K, Matsuoka Y, Nagai S, Yamagishi T, Maeda T, Honda K, Okekawa A, Watanabe S, Yaku K, Okuzaki D, Otsubo R, Nomoto M, Inokuchi K, Nakagawa T, Wada T, Yasui T, Sasaoka T. Food odor perception promotes systemic lipid utilization. Nat Metab 2022; 4:1514-1531. [PMID: 36376564 DOI: 10.1038/s42255-022-00673-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 09/30/2022] [Indexed: 11/16/2022]
Abstract
Food cues during fasting elicit Pavlovian conditioning to adapt for anticipated food intake. However, whether the olfactory system is involved in metabolic adaptations remains elusive. Here we show that food-odor perception promotes lipid metabolism in male mice. During fasting, food-odor stimulation is sufficient to increase serum free fatty acids via adipose tissue lipolysis in an olfactory-memory-dependent manner, which is mediated by the central melanocortin and sympathetic nervous systems. Additionally, stimulation with a food odor prior to refeeding leads to enhanced whole-body lipid utilization, which is associated with increased sensitivity of the central agouti-related peptide system, reduced sympathetic activity and peripheral tissue-specific metabolic alterations, such as an increase in gastrointestinal lipid absorption and hepatic cholesterol turnover. Finally, we show that intermittent fasting coupled with food-odor stimulation improves glycemic control and prevents insulin resistance in diet-induced obese mice. Thus, olfactory regulation is required for maintaining metabolic homeostasis in environments with either an energy deficit or energy surplus, which could be considered as part of dietary interventions against metabolic disorders.
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Affiliation(s)
- Hiroshi Tsuneki
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan.
| | - Masanori Sugiyama
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Toshihiro Ito
- Laboratory of Proteome Research, National Institutes of Biomedical Innovation, Health, and Nutrition, Osaka, Japan
| | - Kiyofumi Sato
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Hiroki Matsuda
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Kengo Onishi
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Koharu Yubune
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Yukina Matsuoka
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Sanaka Nagai
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Towa Yamagishi
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Takahiro Maeda
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Kosuke Honda
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Akira Okekawa
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Shiro Watanabe
- Division of Nutritional Biochemistry, University of Toyama, Toyama, Japan
| | - Keisuke Yaku
- Department of Molecular and Medical Pharmacology, University of Toyama, Toyama, Japan
| | - Daisuke Okuzaki
- Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Ryota Otsubo
- Laboratory of Infectious Diseases and Immunity, National Institutes of Biomedical Innovation, Health, and Nutrition, Osaka, Japan
- Laboratory of Immunobiologics Evaluation, Center for Vaccine and Adjuvant Research, National Institutes of Biomedical Innovation, Health, and Nutrition, Osaka, Japan
| | - Masanori Nomoto
- Department of Biochemistry, University of Toyama, Toyama, Japan
- Research Centre for Idling Brain Science, University of Toyama, Toyama, Japan
| | - Kaoru Inokuchi
- Department of Biochemistry, University of Toyama, Toyama, Japan
- Research Centre for Idling Brain Science, University of Toyama, Toyama, Japan
| | - Takashi Nakagawa
- Department of Molecular and Medical Pharmacology, University of Toyama, Toyama, Japan
| | - Tsutomu Wada
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan
| | - Teruhito Yasui
- Laboratory of Infectious Diseases and Immunity, National Institutes of Biomedical Innovation, Health, and Nutrition, Osaka, Japan.
- Laboratory of Immunobiologics Evaluation, Center for Vaccine and Adjuvant Research, National Institutes of Biomedical Innovation, Health, and Nutrition, Osaka, Japan.
- Laboratory of Pharmaceutical Integrated Omics, Department of Pharmaceutical Engineering, Facility of Engineering, Toyama Prefectural University, Toyama, Japan.
| | - Toshiyasu Sasaoka
- Department of Clinical Pharmacology, University of Toyama, Toyama, Japan.
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11
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Kolling LJ, Tatti R, Lowry T, Loeven AM, Fadool JM, Fadool DA. Modulating the Excitability of Olfactory Output Neurons Affects Whole-Body Metabolism. J Neurosci 2022; 42:5966-5990. [PMID: 35710623 PMCID: PMC9337614 DOI: 10.1523/jneurosci.0190-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 01/29/2023] Open
Abstract
Metabolic state can alter olfactory sensitivity, but it is unknown whether the activity of the olfactory bulb (OB) may fine tune metabolic homeostasis. Our objective was to use CRISPR gene editing in male and female mice to enhance the excitability of mitral/tufted projection neurons (M/TCs) of the OB to test for improved metabolic health. Ex vivo slice recordings of MCs in CRISPR mice confirmed increased excitability due the targeted loss of Kv1.3 channels, which resulted in a less negative resting membrane potential (RMP), enhanced action potential (AP) firing, and insensitivity to the selective channel blocker margatoxin (MgTx). CRISPR mice exhibited enhanced odor discrimination using a habituation/dishabituation paradigm. CRISPR mice were challenged for 25 weeks with a moderately high-fat (MHF) diet, and compared with littermate controls, male mice were resistance to diet-induced obesity (DIO). Female mice did not exhibit DIO. CRISPR male mice gained less body weight, accumulated less white adipose tissue, cleared a glucose challenge more quickly, and had less serum leptin and liver triglycerides. CRISPR male mice consumed equivalent calories as control littermates, and had unaltered energy expenditure (EE) and locomotor activity, but used more fats for metabolic substrate over that of carbohydrates. Counter to CRISPR-engineered mice, by using chemogenetics to decrease M/TC excitability in male mice, activation of inhibitory designer receptors exclusively activated by designer drugs (DREADDs) caused a decrease in odor discrimination, and resulted in a metabolic profile that was obesogenic, mice had reduced EE and oxygen consumption (VO2). We conclude that the activity of M/TC projection neurons canonically carries olfactory information and simultaneously can regulate whole-body metabolism.SIGNIFICANCE STATEMENT The olfactory system drives food choice, and olfactory sensitivity is strongly correlated to hunger and fullness. Olfactory function thereby influences nutritional balance and obesity outcomes. Obesity has become a health and financial crisis in America, shortening life expectancy and increasing the severity of associated illnesses. It is expected that 51% of Americans will be obese by the year 2030. Using CRISPR gene editing and chemogenetic approaches, we discovered that changing the excitability of output neurons in the olfactory bulb (OB) affects metabolism and body weight stabilization in mice. Our results suggest that long-term therapeutic targeting of OB activity to higher processing centers may be a future clinical treatment of obesity or type II Diabetes.
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Affiliation(s)
- Louis John Kolling
- Institute of Molecular Biophysics, The Florida State University, Tallahassee, Florida 32306
| | - Roberta Tatti
- Department of Biological Science, The Florida State University, Tallahassee, Florida 32306
| | - Troy Lowry
- Department of Biological Science, The Florida State University, Tallahassee, Florida 32306
| | - Ashley M Loeven
- Department of Biological Science, The Florida State University, Tallahassee, Florida 32306
| | - James M Fadool
- Department of Biological Science, The Florida State University, Tallahassee, Florida 32306
- Program in Neuroscience, The Florida State University, Tallahassee, Florida 32306
| | - Debra Ann Fadool
- Institute of Molecular Biophysics, The Florida State University, Tallahassee, Florida 32306
- Department of Biological Science, The Florida State University, Tallahassee, Florida 32306
- Program in Neuroscience, The Florida State University, Tallahassee, Florida 32306
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12
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Jovanovic P, Riera CE. Olfactory system and energy metabolism: a two-way street. Trends Endocrinol Metab 2022; 33:281-291. [PMID: 35177346 DOI: 10.1016/j.tem.2022.01.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/11/2022] [Accepted: 01/16/2022] [Indexed: 12/31/2022]
Abstract
Olfactory perception guides daily decisions regarding food consumption, social interactions, and predator avoidance in all mammalian species. Volatile inputs, comprising odorants and pheromones, are relayed to the olfactory bulb (OB) from nasal sensory neurons cells and transferred to secondary processing regions within the brain. Olfaction has recently been shown to shape homeostatic and maladaptive processes of energy intake and expenditure through neuronal circuits involving the medial basal hypothalamus. Reciprocally, gastrointestinal hormones, such as ghrelin and leptin, the secretion of which depends on satiety and adiposity levels, might also influence olfactory sensitivity to alter food-seeking behaviors. Here, in addition to reviewing recent updates on identifying these neuronal networks, we also discuss how bidirectional neurocircuits existing between olfactory and energy processing centers can become dysregulated during obesity.
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Affiliation(s)
- Predrag Jovanovic
- Center for Neural Science and Medicine, Biomedical Sciences Department and Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, 127 South San Vicente Boulevard, Los Angeles, CA 90048, USA
| | - Celine E Riera
- Center for Neural Science and Medicine, Biomedical Sciences Department and Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, 127 South San Vicente Boulevard, Los Angeles, CA 90048, USA; Department of Neurology, Cedars-Sinai Medical Center, Movement Disorder Program, 127 South San Vicente Boulevard, Los Angeles, CA 90048, USA; David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
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13
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Chen XY, Chen L, Yang W, Xie AM. GLP-1 Suppresses Feeding Behaviors and Modulates Neuronal Electrophysiological Properties in Multiple Brain Regions. Front Mol Neurosci 2022; 14:793004. [PMID: 34975402 PMCID: PMC8718614 DOI: 10.3389/fnmol.2021.793004] [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] [Received: 10/11/2021] [Accepted: 11/29/2021] [Indexed: 11/24/2022] Open
Abstract
The glucagon-like peptide-1 (GLP-1) plays important roles in the regulation of food intake and energy metabolism. Peripheral or central GLP-1 suppresses food intake and reduces body weight. The electrophysiological properties of neurons in the mammalian central nervous system reflect the neuronal excitability and the functional organization of the brain. Recent studies focus on elucidating GLP-1-induced suppression of feeding behaviors and modulation of neuronal electrophysiological properties in several brain regions. Here, we summarize that activation of GLP-1 receptor (GLP-1R) suppresses food intake and induces postsynaptic depolarization of membrane potential and/or presynaptic modulation of glutamatergic or GABAergic neurotransmission in brain nuclei located within the medulla oblongata, pons, mesencephalon, diencephalon, and telencephalon. This review may provide a background to guide future research about the cellular mechanisms of GLP-1-induced feeding inhibition.
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Affiliation(s)
- Xin-Yi Chen
- Department of International Medicine, Affiliated Hospital of Qingdao University, Qingdao, China.,Department of Neurology, Affiliated Hospital of Qingdao University, Qingdao, China
| | - Lei Chen
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Wu Yang
- Department of International Medicine, Affiliated Hospital of Qingdao University, Qingdao, China
| | - An-Mu Xie
- Department of Neurology, Affiliated Hospital of Qingdao University, Qingdao, China
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14
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Chelette BM, Loeven AM, Gatlin DN, Landi Conde DR, Huffstetler CM, Qi M, Fadool DA. Consumption of dietary fat causes loss of olfactory sensory neurons and associated circuitry that is not mitigated by voluntary exercise in mice. J Physiol 2021; 600:1473-1495. [PMID: 34807463 PMCID: PMC10102708 DOI: 10.1113/jp282112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 11/05/2021] [Indexed: 12/12/2022] Open
Abstract
Excess nutrition causes loss of olfactory sensory neurons (OSNs) and reduces odour discrimination and odour perception in mice. To separate diet-induced obesity from the consumption of dietary fat, we designed pair-feeding experiments whereby mice were maintained on isocaloric diets for 5 months, which prevented increased fat storage. To test our hypothesis that adiposity was not a prerequisite for loss of OSNs and bulbar projections, we used male and female mice with an odorant receptor-linked genetic reporter (M72tauLacZ; Olfr160) to visualize neural circuitry changes resulting from elevated fat in the diet. Simultaneously we monitored glucose clearance (diagnostic for prediabetes), body fat deposition, ingestive behaviours, select inflammatory markers and energy metabolism. Axonal projections to defined olfactory glomeruli were visualized in whole-mount brains, and the number of OSNs was manually counted across whole olfactory epithelia. After being pair fed a moderately high-fat (MHF) diet, mice of both sexes had body weight, adipose deposits, energy expenditure, respiratory exchange ratios and locomotor activity that were unchanged from control-fed mice. Despite this, they were still found to lose OSNs and associated bulbar projections. Even with unchanged adipocyte storage, pair-fed animals had an elevation in TNF cytokines and an intermediate ability for glucose clearance. Albeit improving health metrics, access to voluntary running while consuming an ad libitum fatty diet still precipitated a loss of OSNs and associated axonal projections for male mice. Our results support that long-term macronutrient imbalance can drive anatomical loss in the olfactory system regardless of total energy expenditure. KEY POINTS: Obesity can disrupt the structure and function of organ systems, including the olfactory system that is important for food selection and satiety. We designed dietary treatments in mice such that mice received fat, but the total calories provided were the same as in control diets so that they would not gain weight or increase adipose tissue. Mice that were not obese but consumed isocaloric fatty diets still lost olfactory neuronal circuits, had fewer numbers of olfactory neurons, had an elevation in inflammatory signals and had an intermediate ability to clear glucose (prediabetes). Mice were allowed access to running wheels while consuming fatty diets, yet still lost olfactory structures. We conclude that a long-term imbalance in nutrition that favours fat in the diet disrupts the olfactory system of mice in the absence of obesity.
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Affiliation(s)
- Brandon M Chelette
- Department of Biological Science, Florida State University, Tallahassee, FL, USA.,Programs in Neuroscience, Florida State University, Tallahassee, FL, USA
| | - Ashley M Loeven
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Destinee N Gatlin
- Department of Biological Science, Florida State University, Tallahassee, FL, USA.,Programs in Neuroscience, Florida State University, Tallahassee, FL, USA
| | - Daniel R Landi Conde
- Department of Biological Science, Florida State University, Tallahassee, FL, USA.,Programs in Neuroscience, Florida State University, Tallahassee, FL, USA
| | - Carley M Huffstetler
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Meizhu Qi
- Department of Biological Science, Florida State University, Tallahassee, FL, USA.,Programs in Neuroscience, Florida State University, Tallahassee, FL, USA
| | - Debra Ann Fadool
- Department of Biological Science, Florida State University, Tallahassee, FL, USA.,Programs in Neuroscience, Florida State University, Tallahassee, FL, USA.,Molecular Biophysics, Florida State University, Tallahassee, FL, USA
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15
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Naseem MU, Tajti G, Gaspar A, Szanto TG, Borrego J, Panyi G. Optimization of Pichia pastoris Expression System for High-Level Production of Margatoxin. Front Pharmacol 2021; 12:733610. [PMID: 34658872 PMCID: PMC8511391 DOI: 10.3389/fphar.2021.733610] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/30/2021] [Indexed: 11/16/2022] Open
Abstract
Margatoxin (MgTx) is a high-affinity blocker of voltage-gated potassium (Kv) channels. It inhibits Kv1.1–Kv1.3 ion channels in picomolar concentrations. This toxin is widely used to study physiological function of Kv ion channels in various cell types, including immune cells. Isolation of native MgTx in large quantities from scorpion venom is not affordable. Chemical synthesis and recombinant production in Escherichia coli need in vitro oxidative refolding for proper disulfide bond formation, resulting in a very low yield of peptide production. The Pichia pastoris expression system offers an economical approach to overcome all these limitations and gives a higher yield of correctly refolded recombinant peptides. In this study, improved heterologous expression of recombinant MgTx (rMgTx) in P. pastoris was obtained by using preferential codons, selecting the hyper-resistant clone against Zeocin, and optimizing the culturing conditions. About 36 ± 4 mg/L of >98% pure His-tagged rMgTx (TrMgTx) was produced, which is a threefold higher yield than has been previously reported. Proteolytic digestion of TrMgTx with factor Xa generated untagged rMgTx (UrMgTx). Both TrMgTx and UrMgTx blocked the Kv1.2 and Kv1.3 currents (patch-clamp) (Kd for Kv1.2 were 64 and 14 pM, and for Kv1.3, 86 and 50 pM, respectively) with comparable potency to the native MgTx. The analysis of the binding kinetics showed that TrMgTx had a lower association rate than UrMgTx for both Kv1.2 and Kv1.3. The dissociation rate of both the analogues was the same for Kv1.3. However, in the case of Kv1.2, TrMgTx showed a much higher dissociation rate with full recovery of the block than UrMgTx. Moreover, in a biological functional assay, both peptides significantly downregulated the expression of early activation markers IL2R and CD40L in activated CD4+ TEM lymphocytes whose activation was Kv1.3 dependent. In conclusion, the authors report that the Pichia expression system is a powerful method to produce disulfide-rich peptides, the overexpression of which could be enhanced noticeably through optimization strategies, making it more cost-effective. Since the presence of the His-tag on rMgTx only mildly altered the block equilibrium and binding kinetics, recombinant toxins could be used in ion channel research without removing the tag and could thus reduce the cost and time demand for toxin production.
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Affiliation(s)
- Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gabor Tajti
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Gaspar
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology, Institute of Chemistry, University of Debrecen, Debrecen, Hungary
| | - Tibor G Szanto
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jesús Borrego
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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