Cardiac-specific deletion of the microtubule-binding protein CENP-F causes dilated cardiomyopathy

Ellen Dees,Cristi L Galindo,Jeffrey N Rottman,R Pierre Hunt,Katherine L Moynihan,David M Bader,Ryan D Pooley,Paul M Miller

doi:10.1242/dmm.008680

Abstract

SUMMARYCENP-F is a large multifunctional protein with demonstrated regulatory roles in cell proliferation, vesicular transport and cell shape through its association with the microtubule (MT) network. Until now, analysis of CENP-F has been limited to in vitro analysis. Here, using a Cre-loxP system, we report the in vivo disruption of CENP-F gene function in murine cardiomyocytes, a cell type displaying high levels of CENP-F expression. Loss of CENP-F function in developing myocytes leads to decreased cell division, blunting of trabeculation and an initially smaller, thin-walled heart. Still, embryos are born at predicted mendelian ratios on an outbred background. After birth, hearts lacking CENP-F display disruption of their intercalated discs and loss of MT integrity particularly at the costamere; these two structures are essential for cell coupling/electrical conduction and force transduction in the heart. Inhibition of myocyte proliferation and cell coupling as well as loss of MT maintenance is consistent with previous reports of generalized CENP-F function in isolated cells. One hundred percent of these animals develop progressive dilated cardiomyopathy with heart block and scarring, and there is a 20% mortality rate. Importantly, although it has long been postulated that the MT cytoskeleton plays a role in the development of heart disease, this study is the first to reveal a direct genetic link between disruption of this network and cardiomyopathy. Finally, this study has broad implications for development and disease because CENP-F loss of function affects a diverse array of cell-type-specific activities in other organs.

Highlights

Given the high expression of murine CENP-F in the developing heart (Fig. 1A), mice with the first five exons of CENP-F flanked by loxP sites (Fig. 1B) were crossed with a cardiac troponin T-Cre mouse to generate a cardiomyocyte-specific targeted deletion of CENP-F
CENP-F is ubiquitous in the developing embryo but the highest levels of expression are observed in the heart and regions of the brain. (B) A schematic presentation of the targeted CENP-F gene with the location of loxP sites marked by yellow arrowheads
Because high-level CENPF expression parallels the period of cardiomyocyte mitosis and CENP-F is thought to regulate cell proliferation in vitro, we examined the impact of CENP-F loss of function on myocyte proliferation

Summary

Introduction

Cardiomyopathies are divided into three categories on the basis of the phenotype of the diseased ventricles: hypertrophic, dilated or restrictive (Franz et al, 2001; Seidman and Seidman, 2001). Single gene defects in sarcomeric or other cardiac muscle proteins are important causes of primary cardiomyopathy Most of these gene defects cause hypertrophic forms of cardiomyopathy, but others can cause either hypertrophic or dilated cardiomyopathy, depending on genetic background or on the specific function of the protein that is affected by the mutation (Franz et al, 2001; Olson et al, 2001; Seidman and Seidman, 2001; Carniel et al, 2005). Mutations in -cardiac actin cause hypertrophic cardiomyopathy when they affect actin-myosin interaction

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