title: TIMP3 Modulates GHR Abundance and GH Sensitivity.
abstract: GH receptor (GHR) binds GH at the cell surface via its extracellular domain and initiates intracellular signal transduction, resulting in important anabolic and metabolic actions. GH signaling is subject to dynamic regulation, which in part is exerted by modulation of cell surface GHR levels. Constitutive and inducible metalloprotease-mediated cleavage of GHR regulate GHR abundance and thereby modulate GH action. We previously demonstrated that GHR proteolysis is catalyzed by the TNF-α converting enzyme (TACE; ADAM17). Tissue inhibitors of metalloproteases-3 (TIMP3) is a natural specific inhibitor of TACE, although mechanisms underlying this inhibition are not yet fully understood. In the current study, we use two model cell lines to examine the relationships between cellular TACE, TIMP3 expression, GHR metalloproteolysis, and GH sensitivity. These two cell lines exhibited markedly different sensitivity to inducible GHR proteolysis, which correlated directly to their relative levels of mature TACE vs unprocessed TACE precursor and indirectly to their levels of cellular TIMP3. Our results implicate TIMP3 as a modulator of cell surface GHR abundance and the ability of GH to promote cellular signaling; these modulatory effects may be conferred by endogenous TIMP3 expression as well as exogenous TIMP3 exposure. Furthermore, our analysis suggests that TIMP3, in addition to regulating the activity of TACE, may also modulate the maturation of TACE, thereby affecting the abundance of the active form of the enzyme.
authors.affiliation: Department of Medicine (Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism, and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; The Institute of Cell Biology (X.W.), Shandong University School of Medicine, Jinan 250012, China; Department of Biochemistry and Biophysics (K.L.), Texas A&M University, College Station, Texas 77843; Department of Surgery (L.A.M.), University of Tennessee College of Medicine Chattanooga, Chattanooga, Tennessee 37403; Department of Medical Pharmacology and Physiology (G.E.D.), University of Missouri School of Medicine, Columbia, Missouri 65212; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Medicine (Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism, and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; The Institute of Cell Biology (X.W.), Shandong University School of Medicine, Jinan 250012, China; Department of Biochemistry and Biophysics (K.L.), Texas A&M University, College Station, Texas 77843; Department of Surgery (L.A.M.), University of Tennessee College of Medicine Chattanooga, Chattanooga, Tennessee 37403; Department of Medical Pharmacology and Physiology (G.E.D.), University of Missouri School of Medicine, Columbia, Missouri 65212; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233.
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Medicine (Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism, and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; The Institute of Cell Biology (X.W.), Shandong University School of Medicine, Jinan 250012, China; Department of Biochemistry and Biophysics (K.L.), Texas A&M University, College Station, Texas 77843; Department of Surgery (L.A.M.), University of Tennessee College of Medicine Chattanooga, Chattanooga, Tennessee 37403; Department of Medical Pharmacology and Physiology (G.E.D.), University of Missouri School of Medicine, Columbia, Missouri 65212; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Loesch
authors.affiliation: Department of Medicine (Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism, and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; The Institute of Cell Biology (X.W.), Shandong University School of Medicine, Jinan 250012, China; Department of Biochemistry and Biophysics (K.L.), Texas A&M University, College Station, Texas 77843; Department of Surgery (L.A.M.), University of Tennessee College of Medicine Chattanooga, Chattanooga, Tennessee 37403; Department of Medical Pharmacology and Physiology (G.E.D.), University of Missouri School of Medicine, Columbia, Missouri 65212; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233.
authors.forename: Larry A
authors.initials: LA
authors.lastname: May
authors.affiliation: Department of Medicine (Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism, and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; The Institute of Cell Biology (X.W.), Shandong University School of Medicine, Jinan 250012, China; Department of Biochemistry and Biophysics (K.L.), Texas A&M University, College Station, Texas 77843; Department of Surgery (L.A.M.), University of Tennessee College of Medicine Chattanooga, Chattanooga, Tennessee 37403; Department of Medical Pharmacology and Physiology (G.E.D.), University of Missouri School of Medicine, Columbia, Missouri 65212; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233.
authors.forename: George E
authors.initials: GE
authors.lastname: Davis
authors.affiliation: Department of Medicine (Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism, and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; The Institute of Cell Biology (X.W.), Shandong University School of Medicine, Jinan 250012, China; Department of Biochemistry and Biophysics (K.L.), Texas A&M University, College Station, Texas 77843; Department of Surgery (L.A.M.), University of Tennessee College of Medicine Chattanooga, Chattanooga, Tennessee 37403; Department of Medical Pharmacology and Physiology (G.E.D.), University of Missouri School of Medicine, Columbia, Missouri 65212; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233.
authors.forename: Jing
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Department of Medicine (Y.Z., J.J., S.J.F.), Division of Endocrinology, Diabetes, and Metabolism, and Department of Cell, Developmental, and Integrative Biology (S.J.F.), University of Alabama at Birmingham, Birmingham, Alabama 35294; The Institute of Cell Biology (X.W.), Shandong University School of Medicine, Jinan 250012, China; Department of Biochemistry and Biophysics (K.L.), Texas A&M University, College Station, Texas 77843; Department of Surgery (L.A.M.), University of Tennessee College of Medicine Chattanooga, Chattanooga, Tennessee 37403; Department of Medical Pharmacology and Physiology (G.E.D.), University of Missouri School of Medicine, Columbia, Missouri 65212; and Endocrinology Section (S.J.F.), Medical Service, Veterans Affairs Medical Center, Birmingham, Alabama 35233.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Frank
mesh_terms: D000072198:ADAM17 Protein; D000818:Animals; D020868:Gene Silencing / Q000187:drug effects; D013006:Growth Hormone / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D053614:Janus Kinase 2 / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D059748:Proteolysis / Q000187:drug effects; D011986:Receptors, Somatotropin / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000378:metabolism*
chemical_list: D011986:Receptors, Somatotropin; D050799:STAT5 Transcription Factor; D019717:Tissue Inhibitor of Metalloproteinase-3; D013006:Growth Hormone; D053614:Janus Kinase 2; D000072198:ADAM17 Protein; D013755:Tetradecanoylphorbol Acetate