1
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Zhou M, Tamburini I, Van C, Molendijk J, Nguyen CM, Chang IYY, Johnson C, Velez LM, Cheon Y, Yeo R, Bae H, Le J, Larson N, Pulido R, Nascimento-Filho CHV, Jang C, Marazzi I, Justice J, Pannunzio N, Hevener AL, Sparks L, Kershaw EE, Nicholas D, Parker BL, Masri S, Seldin MM. Leveraging inter-individual transcriptional correlation structure to infer discrete signaling mechanisms across metabolic tissues. eLife 2024; 12:RP88863. [PMID: 38224289 PMCID: PMC10945578 DOI: 10.7554/elife.88863] [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] [Indexed: 01/16/2024] Open
Abstract
Inter-organ communication is a vital process to maintain physiologic homeostasis, and its dysregulation contributes to many human diseases. Given that circulating bioactive factors are stable in serum, occur naturally, and are easily assayed from blood, they present obvious focal molecules for therapeutic intervention and biomarker development. Recently, studies have shown that secreted proteins mediating inter-tissue signaling could be identified by 'brute force' surveys of all genes within RNA-sequencing measures across tissues within a population. Expanding on this intuition, we reasoned that parallel strategies could be used to understand how individual genes mediate signaling across metabolic tissues through correlative analyses of gene variation between individuals. Thus, comparison of quantitative levels of gene expression relationships between organs in a population could aid in understanding cross-organ signaling. Here, we surveyed gene-gene correlation structure across 18 metabolic tissues in 310 human individuals and 7 tissues in 103 diverse strains of mice fed a normal chow or high-fat/high-sucrose (HFHS) diet. Variation of genes such as FGF21, ADIPOQ, GCG, and IL6 showed enrichments which recapitulate experimental observations. Further, similar analyses were applied to explore both within-tissue signaling mechanisms (liver PCSK9) and genes encoding enzymes producing metabolites (adipose PNPLA2), where inter-individual correlation structure aligned with known roles for these critical metabolic pathways. Examination of sex hormone receptor correlations in mice highlighted the difference of tissue-specific variation in relationships with metabolic traits. We refer to this resource as gene-derived correlations across tissues (GD-CAT) where all tools and data are built into a web portal enabling users to perform these analyses without a single line of code (gdcat.org). This resource enables querying of any gene in any tissue to find correlated patterns of genes, cell types, pathways, and network architectures across metabolic organs.
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Affiliation(s)
- Mingqi Zhou
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Ian Tamburini
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Cassandra Van
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Jeffrey Molendijk
- Department of Anatomy and Physiology, University of MelbourneMelbourneAustralia
| | - Christy M Nguyen
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | | | - Casey Johnson
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Leandro M Velez
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Youngseo Cheon
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Reichelle Yeo
- Translational Research Institute, AdventHealthOrlandoUnited States
| | - Hosung Bae
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Johnny Le
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Natalie Larson
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Ron Pulido
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Carlos HV Nascimento-Filho
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Cholsoon Jang
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Ivan Marazzi
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Jamie Justice
- Veterans Administration Greater Los Angeles Healthcare System, Geriatric Research Education and Clinical Center (GRECC)Los AngelesUnited States
| | - Nicholas Pannunzio
- Divison of Hematology/Oncology, Department of Medicine, UC Irvine HealthIrvineUnited States
| | - Andrea L Hevener
- Department of Medicine, Division of Endocrinology, Diabetes, and Hypertension, David Geffen School of Medicine at UCLALos AngelesUnited States
- Iris Cantor-UCLA Women’s Health Research Center, David Geffen School of Medicine at UCLALos AngelesUnited States
| | - Lauren Sparks
- Translational Research Institute, AdventHealthOrlandoUnited States
| | - Erin E Kershaw
- Division of Endocrinology, Department of Medicine, University of PittsburgPittsburghUnited States
| | - Dequina Nicholas
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
- Department of Molecular Biology and Biochemistry, School of Biological Sciences, University of California IrvineIrvineUnited States
| | - Benjamin L Parker
- Department of Anatomy and Physiology, University of MelbourneMelbourneAustralia
| | - Selma Masri
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
| | - Marcus M Seldin
- Department of Biological Chemistry, UC IrvineIrvineUnited States
- Center for Epigenetics and Metabolism, UC IrvineIrvineUnited States
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Li N, Li C, Li B, Li C, Zhao Q, Huang Z, Shu Y, Qu X, Wang B, Li S, Xing C. Dual Activation of Calcium Channels Using Near-Infrared Responsive Conjugated Oligomer Nanoparticles for Precise Regulation of Blood Glucose Homeostasis. NANO LETTERS 2023; 23:10608-10616. [PMID: 37948661 DOI: 10.1021/acs.nanolett.3c03701] [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: 11/12/2023]
Abstract
The rarity of efficient tools with spatiotemporal resolution and biocompatibility capabilities remains a major challenge for further progress and application of signaling manipulation. Herein, biomimetic conjugated oligomeric nanoparticles (CM-CONs) were developed to precisely modulate blood glucose homeostasis via the two-pronged activation of calcium channels. Under near-infrared (NIR) laser irradiation, CM-CONs efficiently generate local heat and reactive oxygen species (ROS), thereby simultaneously activating thermosensitive transient receptor potential V1 (TRPV1) and ROS-sensitive transient receptor potential A1 (TRPA1) calcium channels in small intestinal endocrine cells. The activation of the channels mediates inward calcium flow and then promotes glucagon-like peptide (GLP-1) secretion. Both in vitro and in vivo studies indicate that CM-CONs effectively regulate glucose homeostasis in diabetic model mice upon NIR light irradiation. This work develops a two-pronged attack strategy for accurately controlling blood glucose homeostasis, holding great prospects in the treatment for diabetes.
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Affiliation(s)
- Ning Li
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
- College of Pharmaceutical Sciences, Soochow University, Suzhou 215000, P. R. China
| | - Chen Li
- School of Public Health, Tianjin Medical University, Tianjin 300070, P. R. China
| | - Boying Li
- School of Chemical Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Chaoqun Li
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Qi Zhao
- College of Pharmaceutical Sciences, Soochow University, Suzhou 215000, P. R. China
| | - Zhongming Huang
- College of Pharmaceutical Sciences, Soochow University, Suzhou 215000, P. R. China
| | - Yue Shu
- School of Public Health, Tianjin Medical University, Tianjin 300070, P. R. China
| | - Xiongwei Qu
- School of Chemical Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Baiqi Wang
- School of Public Health, Tianjin Medical University, Tianjin 300070, P. R. China
| | - Shengliang Li
- College of Pharmaceutical Sciences, Soochow University, Suzhou 215000, P. R. China
| | - Chengfen Xing
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, P. R. China
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3
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Zhou M, Tamburini IJ, Van C, Molendijk J, Nguyen CM, Chang IYY, Johnson C, Velez LM, Cheon Y, Yeo RX, Bae H, Le J, Larson N, Pulido R, Filho C, Jang C, Marazzi I, Justice JN, Pannunzio N, Hevener A, Sparks LM, Kershaw EE, Nicholas D, Parker B, Masri S, Seldin M. Leveraging inter-individual transcriptional correlation structure to infer discrete signaling mechanisms across metabolic tissues. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.10.540142. [PMID: 37214953 PMCID: PMC10197628 DOI: 10.1101/2023.05.10.540142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Abstract/IntroductionInter-organ communication is a vital process to maintain physiologic homeostasis, and its dysregulation contributes to many human diseases. Beginning with the discovery of insulin over a century ago, characterization of molecules responsible for signal between tissues has required careful and elegant experimentation where these observations have been integral to deciphering physiology and disease. Given that circulating bioactive factors are stable in serum, occur naturally, and are easily assayed from blood, they present obvious focal molecules for therapeutic intervention and biomarker development. For example, physiologic dissection of the actions of soluble proteins such as proprotein convertase subtilisin/kexin type 9 (PCSK9) and glucagon-like peptide 1 (GLP1) have yielded among the most promising therapeutics to treat cardiovascular disease and obesity, respectively1–4. A major obstacle in the characterization of such soluble factors is that defining their tissues and pathways of action requires extensive experimental testing in cells and animal models. Recently, studies have shown that secreted proteins mediating inter-tissue signaling could be identified by “brute-force” surveys of all genes within RNA-sequencing measures across tissues within a population5–9. Expanding on this intuition, we reasoned that parallel strategies could be used to understand how individual genes mediate signaling across metabolic tissues through correlative analyses of gene variation between individuals. Thus, comparison of quantitative levels of gene expression relationships between organs in a population could aid in understanding cross-organ signaling. Here, we surveyed gene-gene correlation structure across 18 metabolic tissues in 310 human individuals and 7 tissues in 103 diverse strains of mice fed a normal chow or HFHS diet. Variation of genes such asFGF21, ADIPOQ, GCGandIL6showed enrichments which recapitulate experimental observations. Further, similar analyses were applied to explore both within-tissue signaling mechanisms (liverPCSK9) as well as genes encoding enzymes producing metabolites (adiposePNPLA2), where inter-individual correlation structure aligned with known roles for these critical metabolic pathways. Examination of sex hormone receptor correlations in mice highlighted the difference of tissue-specific variation in relationships with metabolic traits. We refer to this resource asGene-DerivedCorrelationsAcrossTissues (GD-CAT) where all tools and data are built into a web portal enabling users to perform these analyses without a single line of code (gdcat.org). This resource enables querying of any gene in any tissue to find correlated patterns of genes, cell types, pathways and network architectures across metabolic organs.
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Affiliation(s)
- Mingqi Zhou
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Ian J. Tamburini
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Cassandra Van
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Jeffrey Molendijk
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, VIC, Australia
| | - Christy M Nguyen
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | | | - Casey Johnson
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Leandro M. Velez
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Youngseo Cheon
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Reichelle X. Yeo
- Translational Research Institute, AdventHealth, Orlando, FL, USA
| | - Hosung Bae
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Johnny Le
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Natalie Larson
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Ron Pulido
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Carlos Filho
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Cholsoon Jang
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Ivan Marazzi
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Jamie N. Justice
- Veterans Administration Greater Los Angeles Healthcare System, Geriatric Research Education and Clinical Center (GRECC), Los Angeles, CA, USA
| | - Nicholas Pannunzio
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Andrea Hevener
- Department of Medicine, Division of Endocrinology, Diabetes, and Hypertension, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Iris Cantor-UCLA Women’s Health Research Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Lauren M. Sparks
- Translational Research Institute, AdventHealth, Orlando, FL, USA
| | - Erin E. Kershaw
- Department of Internal Medicine, Section On Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Dequina Nicholas
- Division of Endocrinology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Benjamin Parker
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, VIC, Australia
| | - Selma Masri
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
- Center for Epigenetics and Metabolism, UC Irvine. Irvine, CA, USA
| | - Marcus Seldin
- Department of Biological Chemistry, UC Irvine. Irvine, CA, USA
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Lu L, Chen J, Tao W, Wang Z, Liu D, Zhou J, Wu X, Sun H, Li W, Tanabe G, Muraoka O, Zhao B, Wu L, Xie W. Design and Synthesis of Sulfonium Derivatives: A Novel Class of α-Glucosidase Inhibitors with Potent In Vivo Antihyperglycemic Activities. J Med Chem 2023; 66:3484-3498. [PMID: 36812150 DOI: 10.1021/acs.jmedchem.2c01984] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
We report the first attempt of double-spot structural modification on a side-chain moiety of sulfonium-type α-glucosidase inhibitors isolated from genus Salacia. A series of sulfonium salts with benzylidene acetal linkage at the C3' and C5' positions were designed and synthesized. In vitro enzyme inhibition evaluation showed that compounds with a strong electron-withdrawing group attached at the ortho position on the phenyl ring present stronger inhibitory activities. Notably, the most potent inhibitor 21b (1.0 mpk) can exhibit excellent hypoglycemic effects in mice, which can still compete with those of acarbose (20.0 mpk). Molecular docking of 21b demonstrated that besides conventional interacting patterns, the newly introduced benzylidene acetal moiety plays an important role in anchoring the whole molecule in a concave pocket of the enzyme. The successful identification of 21b as a lead compound for new drug discovery may provide a means for structure modification and diversification of the distinguished sulfonium-type α-glucosidase inhibitors.
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Affiliation(s)
- Lu Lu
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Jingyi Chen
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Wenxiang Tao
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Zhimei Wang
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Dan Liu
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Jiahui Zhou
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Xiaoxing Wu
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Haopeng Sun
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Wei Li
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Genzoh Tanabe
- Faculty of Pharmacy Kinki University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan
| | - Osamu Muraoka
- Faculty of Pharmacy Kinki University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan
| | - Bo Zhao
- Department of Chemical and Material Science, Nanjing Normal University, Nanjing 210009, P. R. China
| | - Liang Wu
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing 210009, P. R. China
| | - Weijia Xie
- State Key Laboratory of Natural Medicines (SKLNM) and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, P. R. China
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Wan W, Qin Q, Xie L, Zhang H, Wu F, Stevens RC, Liu Y. GLP-1R Signaling and Functional Molecules in Incretin Therapy. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020751. [PMID: 36677809 PMCID: PMC9866634 DOI: 10.3390/molecules28020751] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 01/14/2023]
Abstract
Glucagon-like peptide-1 receptor (GLP-1R) is a critical therapeutic target for type 2 diabetes mellitus (T2DM). The GLP-1R cellular signaling mechanism relevant to insulin secretion and blood glucose regulation has been extensively studied. Numerous drugs targeting GLP-1R have entered clinical treatment. However, novel functional molecules with reduced side effects and enhanced therapeutic efficacy are still in high demand. In this review, we summarize the basis of GLP-1R cellular signaling, and how it is involved in the treatment of T2DM. We review the functional molecules of incretin therapy in various stages of clinical trials. We also outline the current strategies and emerging techniques that are furthering the development of novel therapeutic drugs for T2DM and other metabolic diseases.
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Affiliation(s)
- Wenwei Wan
- iHuman Institute, ShanghaiTech University, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Qikai Qin
- iHuman Institute, ShanghaiTech University, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Linshan Xie
- iHuman Institute, ShanghaiTech University, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Hanqing Zhang
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Fan Wu
- Structure Therapeutics, South San Francisco, CA 94080, USA
| | - Raymond C. Stevens
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- Structure Therapeutics, South San Francisco, CA 94080, USA
- Correspondence: (R.C.S.); (Y.L.)
| | - Yan Liu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
- Correspondence: (R.C.S.); (Y.L.)
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6
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Elevated Glucagon-like Peptide-1 Receptor Level in the Paraventricular Hypothalamic Nucleus of Type 2 Diabetes Mellitus Patients. Int J Mol Sci 2022; 23:ijms232415945. [PMID: 36555587 PMCID: PMC9781792 DOI: 10.3390/ijms232415945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) agonists have been approved for the treatment of type 2 diabetes mellitus (T2DM); however, the brain actions of these drugs are not properly established. We used post mortem microdissected human hypothalamic samples for RT-qPCR and Western blotting. For in situ hybridization histochemistry and immunolabelling, parallel cryosections were prepared from the hypothalamus. We developed in situ hybridization probes for human GLP-1R and oxytocin. In addition, GLP-1 and oxytocin were visualized by immunohistochemistry. Radioactive in situ hybridization histochemistry revealed abundant GLP-1R labelling in the human paraventricular hypothalamic nucleus (PVN), particularly in its magnocellular subdivision (PVNmc). Quantitative analysis of the mRNA signal demonstrated increased GLP-1R expression in the PVNmc in post mortem hypothalamic samples from T2DM subjects as compared to controls, while there was no difference in the expression level of GLP-1R in the other subdivisions of the PVN, the hypothalamic dorsomedial and infundibular nuclei. Our results in the PVN were confirmed by RT-qPCR. Furthermore, we demonstrated by Western blot technique that the GLP-1R protein level was also elevated in the PVN of T2DM patients. GLP-1 fibre terminals were also observed in the PVNmc closely apposing oxytocin neurons using immunohistochemistry. The data suggest that GLP-1 activates GLP-1Rs in the PVNmc and that GLP-1R is elevated in T2DM patients, which may be related to the dysregulation of feeding behaviour and glucose homeostasis in T2DM.
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