title: SPEG (Striated Muscle Preferentially Expressed Protein Kinase) Is Essential for Cardiac Function by Regulating Junctional Membrane Complex Activity.
abstract: BACKGROUND
  Junctional membrane complexes (JMCs) in myocytes are critical microdomains, in which excitation-contraction coupling occurs. Structural and functional disruption of JMCs underlies contractile dysfunction in failing hearts. However, the role of newly identified JMC protein SPEG (striated muscle preferentially expressed protein kinase) remains unclear.
  
  
  OBJECTIVE
  To determine the role of SPEG in healthy and failing adult hearts.
  
  
  RESULTS
  Proteomic analysis of immunoprecipitated JMC proteins ryanodine receptor type 2 and junctophilin-2 (JPH2) followed by mass spectrometry identified the serine-threonine kinase SPEG as the only novel binding partner for both proteins. Real-time polymerase chain reaction revealed the downregulation of SPEG mRNA levels in failing human hearts. A novel cardiac myocyte-specific Speg conditional knockout (MCM-Spegfl/fl) model revealed that adult-onset SPEG deficiency results in heart failure (HF). Calcium (Ca2+) and transverse-tubule imaging of ventricular myocytes from MCM-Spegfl/flmice post HF revealed both increased sarcoplasmic reticulum Ca2+spark frequency and disrupted JMC integrity. Additional studies revealed that transverse-tubule disruption precedes the development of HF development in MCM-Spegfl/flmice. Although total JPH2 levels were unaltered, JPH2 phosphorylation levels were found to be reduced in MCM-Spegfl/flmice, suggesting that loss of SPEG phosphorylation of JPH2 led to transverse-tubule disruption, a precursor of HF development in SPEG-deficient mice.
  
  
  CONCLUSIONS
  The novel JMC protein SPEG is downregulated in human failing hearts. Acute loss of SPEG in mouse hearts causes JPH2 dephosphorylation and transverse-tubule loss associated with downstream Ca2+mishandling leading to HF. Our study suggests that SPEG could be a novel target for the treatment of HF.
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Ann P
authors.initials: AP
authors.lastname: Quick
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Qiongling
authors.initials: Q
authors.lastname: Wang
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Leonne E
authors.initials: LE
authors.lastname: Philippen
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Giselle
authors.initials: G
authors.lastname: Barreto-Torres
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: David Y
authors.initials: DY
authors.lastname: Chiang
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: David
authors.initials: D
authors.lastname: Beavers
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Guoliang
authors.initials: G
authors.lastname: Wang
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Maha
authors.initials: M
authors.lastname: Khalid
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Julia O
authors.initials: JO
authors.lastname: Reynolds
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Hannah M
authors.initials: HM
authors.lastname: Campbell
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Jordan
authors.initials: J
authors.lastname: Showell
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Mark D
authors.initials: MD
authors.lastname: McCauley
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
authors.forename: Arjen
authors.initials: A
authors.lastname: Scholten
authors.affiliation: From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.). wehrens@bcm.edu.
authors.forename: Xander H T
authors.initials: XH
authors.lastname: Wehrens
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D005260:Female; D057809:HEK293 Cells; D006333:Heart Failure / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008875:Middle Aged; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000096:biosynthesis* / Q000235:genetics; D040901:Proteomics / Q000379:methods*
chemical_list: D008565:Membrane Proteins; D009124:Muscle Proteins; D009219:Myosin-Light-Chain Kinase; C000589042:JP2 protein, mouse; C484400:Speg protein, mouse
keywords: calcium signaling; heart failure; mass spectrometry; phosphorylation; proteomics