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Xia YQ, Yang Y, Liu YY, Cheng JX, Liu Y, Li CH, Liu PF. DNA Methylation Analysis Reveals Potential Mechanism in Takifugu rubripes Against Cryptocaryon irritans Infection. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2024; 26:288-305. [PMID: 38446292 DOI: 10.1007/s10126-024-10296-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Accepted: 02/02/2024] [Indexed: 03/07/2024]
Abstract
Takifugu rubripes (T. rubripes) is a valuable commercial fish, and Cryptocaryon irritans (C. irritans) has a significant impact on its aquaculture productivity. DNA methylation is one of the earliest discovered ways of gene epigenetic modification and also an important form of modification, as well as an essential type of alteration that regulates gene expression, including immune response. To further explore the anti-infection mechanism of T. rubripes in inhibiting this disease, we determined genome-wide DNA methylation profiles in the gill of T. rubripes using whole-genome bisulfite sequencing (WGBS) and combined with RNA sequence (RNA-seq). A total of 4659 differentially methylated genes (DMGs) in the gene body and 1546 DMGs in the promoter between the infection and control group were identified. And we identified 2501 differentially expressed genes (DEGs), including 1100 upregulated and 1401 downregulated genes. After enrichment analysis, we identified DMGs and DEGs of immune-related pathways including MAPK, Wnt, ErbB, and VEGF signaling pathways, as well as node genes prkcb, myca, tp53, and map2k2a. Based on the RNA-Seq results, we plotted a network graph to demonstrate the relationship between immune pathways and functional related genes, in addition to gene methylation and expression levels. At the same time, we predicted the CpG island and transcription factor of four immune-related key genes prkcb and mapped the gene structure. These unique discoveries could be helpful in the understanding of C. irritans pathogenesis, and the candidate genes screened may serve as optimum methylation-based biomarkers that can be utilized for the correct diagnosis and therapy T. rubripes in the development of the ability to resist C. irritans infection.
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Affiliation(s)
- Yu-Qing Xia
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, People's Republic of China
- Key Laboratory of Environment Controlled Aquaculture (Dalian Ocean University), Ministry of Education, 52 Heishijiao Street, Dalian, 116023, People's Republic of China
| | - Yi Yang
- Key Laboratory of Environment Controlled Aquaculture (Dalian Ocean University), Ministry of Education, 52 Heishijiao Street, Dalian, 116023, People's Republic of China
- College of Marine Technology and Environment, Dalian Ocean University, 52 Heishijiao Street, Dalian, 116023, People's Republic of China
| | - Yan-Yun Liu
- Key Laboratory of Environment Controlled Aquaculture (Dalian Ocean University), Ministry of Education, 52 Heishijiao Street, Dalian, 116023, People's Republic of China
- College of Marine Technology and Environment, Dalian Ocean University, 52 Heishijiao Street, Dalian, 116023, People's Republic of China
| | - Jian-Xin Cheng
- Key Laboratory of Environment Controlled Aquaculture (Dalian Ocean University), Ministry of Education, 52 Heishijiao Street, Dalian, 116023, People's Republic of China
- College of Life Science, Liaoning Normal University, Dalian, 116081, People's Republic of China
| | - Ying Liu
- Key Laboratory of Environment Controlled Aquaculture (Dalian Ocean University), Ministry of Education, 52 Heishijiao Street, Dalian, 116023, People's Republic of China
- College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, People's Republic of China
| | - Cheng-Hua Li
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, People's Republic of China.
| | - Peng-Fei Liu
- Key Laboratory of Environment Controlled Aquaculture (Dalian Ocean University), Ministry of Education, 52 Heishijiao Street, Dalian, 116023, People's Republic of China.
- College of Marine Technology and Environment, Dalian Ocean University, 52 Heishijiao Street, Dalian, 116023, People's Republic of China.
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Wade H, Pan K, Duan Q, Kaluzny S, Pandey E, Fatumoju L, Saraswathi V, Wu R, Harris EN, Su Q. Akkermansia muciniphila and its membrane protein ameliorates intestinal inflammatory stress and promotes epithelial wound healing via CREBH and miR-143/145. J Biomed Sci 2023; 30:38. [PMID: 37287024 DOI: 10.1186/s12929-023-00935-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 05/30/2023] [Indexed: 06/09/2023] Open
Abstract
BACKGROUND The intestinal epithelial barrier is the interface for interaction between gut microbiota and host metabolic systems. Akkermansia muciniphila (A. muciniphila) is a key player in the colonic microbiota that resides in the mucus layer, whose abundance is selectively decreased in the faecal microbiota of inflammatory bowel disease (IBD) patients. This study aims to investigate the regulatory mechanism among A. muciniphila, a transcription factor cAMP-responsive element-binding protein H (CREBH), and microRNA-143/145 (miR-143/145) in intestinal inflammatory stress, gut barrier integrity and epithelial regeneration. METHODS A novel mouse model with increased colonization of A muciniphila in the intestine of CREBH knockout mice, an epithelial wound healing assay and several molecular biological techniques were applied in this study. Results were analysed using a homoscedastic 2-tailed t-test. RESULTS Increased colonization of A. muciniphila in mouse gut enhanced expression of intestinal CREBH, which was associated with the mitigation of intestinal endoplasmic reticulum (ER) stress, gut barrier leakage and blood endotoxemia induced by dextran sulfate sodium (DSS). Genetic depletion of CREBH (CREBH-KO) significantly inhibited the expression of tight junction proteins that are associated with gut barrier integrity, including Claudin5 and Claudin8, but upregulated Claudin2, a tight junction protein that enhances gut permeability, resulting in intestinal hyperpermeability and inflammation. Upregulation of CREBH by A. muciniphila further coupled with miR-143/145 promoted intestinal epithelial cell (IEC) regeneration and wound repair via insulin-like growth factor (IGF) and IGFBP5 signalling. Moreover, the gene expressing an outer membrane protein of A. muciniphila, Amuc_1100, was cloned into a mammalian cell-expression vector and successfully expressed in porcine and human IECs. Expression of Amuc_1100 in IECs could recapitulate the health beneficial effect of A. muciniphila on the gut by activating CREBH, inhibiting ER stress and enhancing the expression of genes involved in gut barrier integrity and IEC's regeneration. CONCLUSIONS This study uncovers a novel mechanism that links A. muciniphila and its membrane protein with host CREBH, IGF signalling and miRNAs in mitigating intestinal inflammatory stress-gut barrier permeability and promoting intestinal wound healing. This novel finding may lend support to the development of therapeutic approaches for IBD by manipulating the interaction between host genes, gut bacteria and its bioactive components.
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Affiliation(s)
- Henry Wade
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 5DL, UK
| | - Kaichao Pan
- Department of Medicine, Section of Cardiology, University of Chicago, Chicago, USA
| | - Qihua Duan
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 5DL, UK
| | - Szczepan Kaluzny
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 5DL, UK
| | - Ekta Pandey
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA
| | - Linda Fatumoju
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA
| | | | - Rongxue Wu
- Department of Medicine, Section of Cardiology, University of Chicago, Chicago, USA
| | - Edward N Harris
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA
| | - Qiaozhu Su
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 5DL, UK.
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Yang M, Pan M, Huang D, Liu J, Guo Y, Liu Y, Zhang W. Glucagon Promotes Gluconeogenesis through the GCGR/PKA/CREB/PGC-1α Pathway in Hepatocytes of the Japanese Flounder Paralichthys olivaceus. Cells 2023; 12:cells12071098. [PMID: 37048171 PMCID: PMC10093564 DOI: 10.3390/cells12071098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/25/2023] [Accepted: 03/29/2023] [Indexed: 04/14/2023] Open
Abstract
In order to investigate the mechanism of glucagon regulation of gluconeogenesis, primary hepatocytes of the Japanese flounder (Paralichthys olivaceus) were incubated with synthesized glucagon, and methods based on inhibitors and gene overexpression were employed. The results indicated that glucagon promoted glucose production and increased the mRNA levels of glucagon receptor (gcgr), guanine nucleotide-binding protein Gs α subunit (gnas), adenylate cyclase 2 (adcy2), protein kinase A (pka), cAMP response element-binding protein 1 (creb1), peroxisome proliferator-activated receptor-γ coactivator 1α (pgc-1α), phosphoenolpyruvate carboxykinase 1 (pck1), and glucose-6-phosphatase (g6pc) in the hepatocytes. An inhibitor of GCGR decreased the mRNA expression of gcgr, gnas, adcy2, pka, creb1, pgc-1α, pck1, g6pc, the protein expression of phosphorylated CREB and PGC-1α, and glucose production. The overexpression of gcgr caused the opposite results. An inhibitor of PKA decreased the mRNA expression of pgc-1α, pck1, g6pc, the protein expression of phosphorylated-CREB, and glucose production in hepatocytes. A CREB-targeted inhibitor significantly decreased the stimulation by glucagon of the mRNA expression of creb1, pgc-1α, and gluconeogenic genes, and glucose production decreased accordingly. After incubating the hepatocytes with an inhibitor of PGC-1α, the glucagon-activated mRNA expression of pck1 and g6pc was significantly down-regulated. Together, these results demonstrate that glucagon promotes gluconeogenesis through the GCGR/PKA/CREB/PGC-1α pathway in the Japanese flounder.
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Affiliation(s)
- Mengxi Yang
- The Key Laboratory of Aquaculture Nutrition and Feeds (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao 266003, China
- Hunan Engineering Technology Research Center of Featured Aquatic Resources Utilization, Fisheries College, Hunan Agricultural University, Changsha 410128, China
| | - Mingzhu Pan
- The Key Laboratory of Aquaculture Nutrition and Feeds (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao 266003, China
| | - Dong Huang
- The Key Laboratory of Aquaculture Nutrition and Feeds (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao 266003, China
| | - Jiahuan Liu
- The Key Laboratory of Aquaculture Nutrition and Feeds (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao 266003, China
| | - Yanlin Guo
- The Key Laboratory of Aquaculture Nutrition and Feeds (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao 266003, China
| | - Yue Liu
- The Key Laboratory of Aquaculture Nutrition and Feeds (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao 266003, China
| | - Wenbing Zhang
- The Key Laboratory of Aquaculture Nutrition and Feeds (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao 266003, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
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Lee NH, Myeong SH, Son HJ, Hwang JW, Lee NK, Chang JW, Na DL. Ethionamide Preconditioning Enhances the Proliferation and Migration of Human Wharton's Jelly-Derived Mesenchymal Stem Cells. Int J Mol Sci 2020; 21:E7013. [PMID: 32977637 PMCID: PMC7583833 DOI: 10.3390/ijms21197013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 12/15/2022] Open
Abstract
Mesenchymal stem cells (MSCs) are a useful source for cell-based therapy of a variety of immune-mediated diseases, including neurodegenerative disorders. However, poor migration ability and survival rate of MSCs after brain transplantation hinder the therapeutic effects in the disease microenvironment. Therefore, we attempted to use a preconditioning strategy with pharmacological agents to improve the cell proliferation and migration of MSCs. In this study, we identified ethionamide via the screening of a drug library, which enhanced the proliferation of MSCs. Preconditioning with ethionamide promoted the proliferation of Wharton's jelly-derived MSCs (WJ-MSCs) by activating phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase/extracellular signal-regulated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK)1/2 signaling. Preconditioning with ethionamide also enhanced the migration ability of MSCs by upregulating expression of genes associated with migration, such as C-X-C motif chemokine receptor 4 (CXCR4) and C-X-C motif chemokine ligand 12 (CXCL12). Furthermore, preconditioning with ethionamide stimulated the secretion of paracrine factors, including neurotrophic and growth factors in MSCs. Compared to naïve MSCs, ethionamide-preconditioned MSCs (ETH-MSCs) were found to survive longer in the brain after transplantation. These results suggested that enhancing the biological process of MSCs induced by ethionamide preconditioning presents itself as a promising strategy for enhancing the effectiveness of MSCs-based therapies.
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Affiliation(s)
- Na-Hee Lee
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea; (N.-H.L.); (S.H.M.); (H.J.S.); (J.W.H.)
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Neuroscience Center, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Stem Cell & Regenerative Medicine Institute, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea;
| | - Su Hyeon Myeong
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea; (N.-H.L.); (S.H.M.); (H.J.S.); (J.W.H.)
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Neuroscience Center, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Stem Cell & Regenerative Medicine Institute, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea;
| | - Hyo Jin Son
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea; (N.-H.L.); (S.H.M.); (H.J.S.); (J.W.H.)
- Neuroscience Center, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Stem Cell & Regenerative Medicine Institute, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea;
- School of Medicine, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
| | - Jung Won Hwang
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea; (N.-H.L.); (S.H.M.); (H.J.S.); (J.W.H.)
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Neuroscience Center, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Stem Cell & Regenerative Medicine Institute, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea;
| | - Na Kyung Lee
- Stem Cell & Regenerative Medicine Institute, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea;
- School of Medicine, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Samsung Alzheimer Research Center, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
| | - Jong Wook Chang
- Stem Cell & Regenerative Medicine Institute, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea;
- R & D Center, ENCell Co. Ltd., Seoul 06072, Korea
| | - Duk L. Na
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea; (N.-H.L.); (S.H.M.); (H.J.S.); (J.W.H.)
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Neuroscience Center, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
- Stem Cell & Regenerative Medicine Institute, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea;
- Samsung Alzheimer Research Center, Samsung Medical Center, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
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Lednev EM, Kravchenko IV, Furalyov VA, Lysenko EA, Lemesheva IS, Grushin AA, Dubrov VE, Vinogradova OL, Popov DV. Effect of amino acids on IGF1 gene expression in human myotubes and skeletal muscle. Growth Horm IGF Res 2020; 53-54:101323. [PMID: 32408253 DOI: 10.1016/j.ghir.2020.101323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 04/11/2020] [Accepted: 04/24/2020] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Insulin-like growth factor I (IGF1) is an important regulator of collagen and extracellular matrix protein expression. We aimed to evaluate the effect of amino acids (AAs) on expression of IGF1 and IGF1-dependent genes in human myotubes and skeletal muscle and supposed that AAs administration increases IGF1 levels in blood and expression of IGF1 and IGF1-dependent genes in trained skeletal muscle, thereby reducing training-induced muscle damage. DESIGN Human myotubes were incubated with Arg and Leu for 24 h. Then, the effects of long-term branched chain AAs administration (10 weeks, 0.1 g/kg body mass/day) to volunteers (six subjects per AAs and placebo groups) performing large training volumes regularly (cross country skiers, training twice a day) were examined. RESULTS Incubating the myotubes with AAs increases expression of IGF1 mRNA isoforms and IGF1 secretion by 2-3 times. In athletes, long-term AAs administration increased basal blood levels of IGF1 (~50%) and expression of IGF1Ea mRNA slightly in skeletal muscle. There is no marked increase in expression of COL1A1, COL3A1, COL5A1, and LOX genes in skeletal muscle after AAs administration. However, expression of these genes in the combined group (placebo + AAs; n = 12) significantly correlated with the expression of IGF1Ea mRNA in muscle and did not correlate with IGF1 levels in the blood. CONCLUSIONS AAs administration increases IGF1 expression in vitro and in vivo. To obtain more pronounced changes in expression of IGF1 and IGF1-dependent genes in skeletal muscle, it may be necessary to increase the dose and/or duration of AAs administration.
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Affiliation(s)
- Egor M Lednev
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation.
| | - Irina V Kravchenko
- Federal Research Centre «Fundamentals of Biotechnology» of the Russian Academy of Sciences, 33 build 2, Leninsky prospect, Moscow 119071, Russian Federation
| | - Vladimir A Furalyov
- Federal Research Centre «Fundamentals of Biotechnology» of the Russian Academy of Sciences, 33 build 2, Leninsky prospect, Moscow 119071, Russian Federation
| | - Evgeny A Lysenko
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation
| | - Iulia S Lemesheva
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation
| | - Alexandr A Grushin
- Russian Olympic Committee, Luzhnetskaya Embankment 8, Russia, Moscow 119991, Russian Federation
| | - Vadim E Dubrov
- Lomonosov Moscow State University, Faculty of Fundamental Medicine, 27 build. 1, Lomonosovsky Prospekt, Moscow 119991, Russian Federation
| | - Olga L Vinogradova
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation
| | - Daniil V Popov
- Institute of Biomedical Problems of the RAS, 76A Khoroshevskoye Shosse, Moscow 123007, Russian Federation
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Zhang C, Lian A, Xu Y, Jiang Q. Signal Transduction Mechanisms for Glucagon-Induced Somatolactin Secretion and Gene Expression in Nile Tilapia ( Oreochromis niloticus) Pituitary Cells. Front Endocrinol (Lausanne) 2020; 11:629077. [PMID: 33613457 PMCID: PMC7890253 DOI: 10.3389/fendo.2020.629077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 12/23/2020] [Indexed: 11/13/2022] Open
Abstract
Glucagon (GCG) plays a stimulatory role in pituitary hormone regulation, although previous studies have not defined the molecular mechanism whereby GCG affects pituitary hormone secretion. To this end, we identified two distinct proglucagons, Gcga and Gcgb, as well as GCG receptors, Gcgra and Gcgrb, in Nile tilapia (Oreochromis niloticus). Using the cAMP response element (CRE)-luciferase reporter system, tilapia GCGa and GCGb could reciprocally activate the two GCG receptors expressed in human embryonic kidney 293 (HEK293) cells. Quantitative real-time PCR analysis revealed that differential expression of the Gcga and Gcgb and their cognate receptors Gcgra and Gcgrb was found in the various tissues of tilapia. In particular, the Gcgrb is abundantly expressed in the neurointermediate lobe (NIL) of the pituitary gland. In primary cultures of tilapia NIL cells, GCGb effectively stimulated SL release, with parallel rises in the mRNA levels, and co-incubation with the GCG antagonist prevented GCGb-stimulated SL release. In parallel experiments, GCGb treatment dose-dependently enhanced intracellular cyclic adenosine monophosphate (cAMP) accumulation with increasing inositol 1,4,5-trisphosphate (IP3) concentration and the resulting in transient increases of Ca2+ signals in the primary NIL cell culture. Using selective pharmacological approaches, the adenylyl cyclase (AC)/cAMP/protein kinase A (PKA) and phospholipase C (PLC)/IP3/Ca2+/calmodulin (CaM)/CaMK-II pathways were shown to be involved in GCGb-induced SL release and mRNA expression. Together, these results provide evidence for the first time that GCGb can act at the pituitary level to stimulate SL release and gene expression via GCGRb through the activation of the AC/cAMP/PKA and PLC/IP3/Ca2+/CaM/CaMK-II cascades.
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