Abstract
The molecular and functional expression of serpentine membrane receptors for vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), and calcitonin (CT) were characterized in human thymus and thymomas from myasthenia gravis (MG) patients and thymic epithelial cells either in primary culture (PTEC) or transformed by the simian virus 40 large T (SV40LT) oncogene (LT-TEC). Using RT-PCR combined with Southern analysis, we identified the PCR products corresponding to the receptor (-R) transcripts for VIP, CGRP, and CT in thymus from control subjects and MG patients with either hyperplasia or thymoma. Similar expressions of the VIP- and CGRP-R transcripts were observed in PTEC, whereas the CT-R message was not detected. In LT-TEC, the signals for VIP-R, CGRP-R, and CT-R transcripts were seen with a lower intensity than those in control and MG thymus. In agreement with our molecular analysis, 1) VIP was the most potent peptide among VIP-related peptides (VIP > PACAP > PHM > PHV) to stimulate cAMP production through specific type 1 VIP receptors in both PTEC and LT-TEC; 2) cAMP generation was induced by CGRP in PTEC and by CT in LT-TEC; 3) in frozen thymic sections and by flow cytometry, type 1 VIP-R, CGRP-R, and CT-R were localized in epithelial cells; and 4) in parallel, the transcription of the acetylcholine receptor alpha subunit (the main autoantigen in MG) was induced by CGRP and CT in PTEC and LT-TEC, respectively. Our data suggest that the neuroendocrine peptides VIP, CGRP, and CT may exert functional roles during MG and malignant transformation of the human thymus.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adolescent
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Adult
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Antigens, Viral, Tumor / physiology
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Blotting, Southern
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Calcitonin / pharmacology
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Calcitonin Gene-Related Peptide / pharmacology
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Cell Culture Techniques / methods
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Cell Line, Transformed
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Cell Transformation, Viral
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Child
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Child, Preschool
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Epithelial Cells / cytology
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Epithelial Cells / metabolism
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Flow Cytometry
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Gene Expression Regulation / drug effects
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Gene Expression Regulation / immunology
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Humans
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Immunohistochemistry
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Infant
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Middle Aged
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Myasthenia Gravis / immunology
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Myasthenia Gravis / metabolism*
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Receptors, Calcitonin / biosynthesis
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Receptors, Calcitonin / genetics
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Receptors, Calcitonin / physiology
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Receptors, Calcitonin Gene-Related Peptide / biosynthesis
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Receptors, Calcitonin Gene-Related Peptide / genetics
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Receptors, Calcitonin Gene-Related Peptide / physiology
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Receptors, Cholinergic / genetics
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Receptors, Neuropeptide / biosynthesis*
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Receptors, Neuropeptide / genetics
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Receptors, Neuropeptide / physiology*
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Receptors, Vasoactive Intestinal Peptide / biosynthesis
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Receptors, Vasoactive Intestinal Peptide / genetics
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Receptors, Vasoactive Intestinal Peptide / physiology
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Reverse Transcriptase Polymerase Chain Reaction
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Simian virus 40 / physiology
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Thymoma / metabolism*
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Thymus Gland / cytology
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Thymus Gland / metabolism*
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Vasoactive Intestinal Peptide / pharmacology
Substances
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Antigens, Viral, Tumor
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Receptors, Calcitonin
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Receptors, Calcitonin Gene-Related Peptide
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Receptors, Cholinergic
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Receptors, Neuropeptide
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Receptors, Vasoactive Intestinal Peptide
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Vasoactive Intestinal Peptide
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Calcitonin
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Calcitonin Gene-Related Peptide