Mei Methawasin1, Joshua G Strom1, Rebecca E Slater1, Vanessa Fernandez1, Chandra Saripalli1, Henk Granzier2. 1. From Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson. 2. From Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson. granzier@email.arizona.edu.
Abstract
BACKGROUND: Left ventricular (LV) stiffening contributes to heart failure with preserved ejection fraction (HFpEF), a syndrome with no effective treatment options. Increasing the compliance of titin in the heart has become possible recently through inhibition of the splicing factor RNA binding motif-20. Here, we investigated the effects of increasing the compliance of titin in mice with diastolic dysfunction. METHODS: Mice in which the RNA recognition motif (RRM) of one of the RNA binding motif-20 alleles was floxed and that expressed the MerCreMer transgene under control of the αMHC promoter (referred to as cRbm20ΔRRM mice) were used. Mice underwent transverse aortic constriction (TAC) surgery and deoxycorticosterone acetate (DOCA) pellet implantation. RRM deletion in adult mice was triggered by injecting raloxifene (cRbm20ΔRRM-raloxifene), with dimethyl sulfoxide (DMSO)-injected mice (cRbm20ΔRRM-DMSO) as the control. Diastolic function was investigated with echocardiography and pressure-volume analysis; passive stiffness was studied in LV muscle strips and isolated cardiac myocytes before and after elimination of titin-based stiffness. Treadmill exercise performance was also studied. Titin isoform expression was evaluated with agarose gels. RESULTS: cRbm20ΔRRM-raloxifene mice expressed large titins in the hearts, called supercompliant titin (N2BAsc), which, within 3 weeks after raloxifene injection, made up ≈45% of total titin. TAC/DOCA cRbm20ΔRRM-DMSO mice developed LV hypertrophy and a marked increase in LV chamber stiffness as shown by both pressure-volume analysis and echocardiography. LV chamber stiffness was normalized in TAC/DOCA cRbm20ΔRRM-raloxifene mice that expressed N2BAsc. Passive stiffness measurements on muscle strips isolated from the LV free wall revealed that extracellular matrix stiffness was equally increased in both groups of TAC/DOCA mice (cRbm20ΔRRM-DMSO and cRbm20ΔRRM-raloxifene). However, titin-based muscle stiffness was reduced in the mice that expressed N2BAsc (TAC/DOCAcRbm20ΔRRM-raloxifene). Exercise testing demonstrated significant improvement in exercise tolerance in TAC/DOCA mice that expressed N2BAsc. CONCLUSIONS: Inhibition of the RNA binding motif-20-based titin splicing system upregulates compliant titins, which improves diastolic function and exercise tolerance in the TAC/DOCA model. Titin holds promise as a therapeutic target for heart failure with preserved ejection fraction.
BACKGROUND: Left ventricular (LV) stiffening contributes to heart failure with preserved ejection fraction (HFpEF), a syndrome with no effective treatment options. Increasing the compliance of titin in the heart has become possible recently through inhibition of the splicing factor RNA binding motif-20. Here, we investigated the effects of increasing the compliance of titin in mice with diastolic dysfunction. METHODS:Mice in which the RNA recognition motif (RRM) of one of the RNA binding motif-20 alleles was floxed and that expressed the MerCreMer transgene under control of the αMHC promoter (referred to as cRbm20ΔRRM mice) were used. Mice underwent transverse aortic constriction (TAC) surgery and deoxycorticosterone acetate (DOCA) pellet implantation. RRM deletion in adult mice was triggered by injecting raloxifene (cRbm20ΔRRM-raloxifene), with dimethyl sulfoxide (DMSO)-injected mice (cRbm20ΔRRM-DMSO) as the control. Diastolic function was investigated with echocardiography and pressure-volume analysis; passive stiffness was studied in LV muscle strips and isolated cardiac myocytes before and after elimination of titin-based stiffness. Treadmill exercise performance was also studied. Titin isoform expression was evaluated with agarose gels. RESULTS: cRbm20ΔRRM-raloxifenemice expressed large titins in the hearts, called supercompliant titin (N2BAsc), which, within 3 weeks after raloxifene injection, made up ≈45% of total titin. TAC/DOCA cRbm20ΔRRM-DMSOmice developed LV hypertrophy and a marked increase in LV chamber stiffness as shown by both pressure-volume analysis and echocardiography. LV chamber stiffness was normalized in TAC/DOCA cRbm20ΔRRM-raloxifenemice that expressed N2BAsc. Passive stiffness measurements on muscle strips isolated from the LV free wall revealed that extracellular matrix stiffness was equally increased in both groups of TAC/DOCAmice (cRbm20ΔRRM-DMSO and cRbm20ΔRRM-raloxifene). However, titin-based muscle stiffness was reduced in the mice that expressed N2BAsc (TAC/DOCAcRbm20ΔRRM-raloxifene). Exercise testing demonstrated significant improvement in exercise tolerance in TAC/DOCAmice that expressed N2BAsc. CONCLUSIONS: Inhibition of the RNA binding motif-20-based titin splicing system upregulates compliant titins, which improves diastolic function and exercise tolerance in the TAC/DOCA model. Titin holds promise as a therapeutic target for heart failure with preserved ejection fraction.
Authors: Clyde W Yancy; Mariell Jessup; Biykem Bozkurt; Javed Butler; Donald E Casey; Mark H Drazner; Gregg C Fonarow; Stephen A Geraci; Tamara Horwich; James L Januzzi; Maryl R Johnson; Edward K Kasper; Wayne C Levy; Frederick A Masoudi; Patrick E McBride; John J V McMurray; Judith E Mitchell; Pamela N Peterson; Barbara Riegel; Flora Sam; Lynne W Stevenson; W H Wilson Tang; Emily J Tsai; Bruce L Wilkoff Journal: Circulation Date: 2013-06-05 Impact factor: 29.690
Authors: Anoop K Shetty; Simon G Duckett; Matthew R Ginks; Yinglaing Ma; Manav Sohal; Julian Bostock; Stam Kapetanakis; Jagmeet P Singh; Kawal Rhode; Matthew Wright; Mark D O'Neill; Jaswinder S Gill; Gerald Carr-White; Reza Razavi; Christopher Aldo Rinaldi Journal: Eur Heart J Cardiovasc Imaging Date: 2012-11-22 Impact factor: 6.875
Authors: Wei Guo; Sebastian Schafer; Marion L Greaser; Michael H Radke; Martin Liss; Thirupugal Govindarajan; Henrike Maatz; Herbert Schulz; Shijun Li; Amanda M Parrish; Vita Dauksaite; Padmanabhan Vakeel; Sabine Klaassen; Brenda Gerull; Ludwig Thierfelder; Vera Regitz-Zagrosek; Timothy A Hacker; Kurt W Saupe; G William Dec; Patrick T Ellinor; Calum A MacRae; Bastian Spallek; Robert Fischer; Andreas Perrot; Cemil Özcelik; Kathrin Saar; Norbert Hubner; Michael Gotthardt Journal: Nat Med Date: 2012-05 Impact factor: 53.440
Authors: Steven M Markowitz; Jason M Lewen; Christopher J Wiggenhorn; William T Abraham; Kenneth M Stein; Sei Iwai; Bruce B Lerman Journal: J Cardiovasc Electrophysiol Date: 2008-10-30
Authors: Margaret M Redfield; Horng H Chen; Barry A Borlaug; Marc J Semigran; Kerry L Lee; Gregory Lewis; Martin M LeWinter; Jean L Rouleau; David A Bull; Douglas L Mann; Anita Deswal; Lynne W Stevenson; Michael M Givertz; Elizabeth O Ofili; Christopher M O'Connor; G Michael Felker; Steven R Goldsmith; Bradley A Bart; Steven E McNulty; Jenny C Ibarra; Grace Lin; Jae K Oh; Manesh R Patel; Raymond J Kim; Russell P Tracy; Eric J Velazquez; Kevin J Anstrom; Adrian F Hernandez; Alice M Mascette; Eugene Braunwald Journal: JAMA Date: 2013-03-27 Impact factor: 56.272
Authors: Loek van Heerebeek; Constantijn P M Franssen; Nazha Hamdani; Freek W A Verheugt; G Aernout Somsen; Walter J Paulus Journal: Curr Heart Fail Rep Date: 2012-12
Authors: Michael H Radke; Jun Peng; Yiming Wu; Mark McNabb; O Lynne Nelson; Henk Granzier; Michael Gotthardt Journal: Proc Natl Acad Sci U S A Date: 2007-02-20 Impact factor: 11.205
Authors: Henk L Granzier; Michael H Radke; Jun Peng; Dirk Westermann; O Lynne Nelson; Katharina Rost; Nicholas M P King; Qianli Yu; Carsten Tschöpe; Mark McNabb; Douglas F Larson; Siegfried Labeit; Michael Gotthardt Journal: Circ Res Date: 2009-08-13 Impact factor: 17.367
Authors: Nicholas M P King; Methajit Methawasin; Joshua Nedrud; Nicholas Harrell; Charles S Chung; Michiel Helmes; Henk Granzier Journal: J Gen Physiol Date: 2011-01 Impact factor: 4.086
Authors: Dimitrios Maragiannis; Paulino A Alvarez; Mohamad G Ghosn; Karen Chin; Jeremy J Hinojosa; John M Buergler; Dipan J Shah; Sherif F Nagueh Journal: Int J Cardiovasc Imaging Date: 2017-07-26 Impact factor: 2.357