Physiol. Genomics Journal of Neurophysiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Physiol. Genomics 26: 109-115, 2006. First published May 2, 2006; doi:10.1152/physiolgenomics.00281.2005
1094-8341/06 $8.00
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
26/2/109    most recent
00281.2005v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bilchick, K. C.
Right arrow Articles by Kass, D. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bilchick, K. C.
Right arrow Articles by Kass, D. A.
Received 12 November 2005; accepted in final form 19 April 2006.
Physiological Genomics 26:109-115 (2006)
1094-8341/06 $8.00 © 2006 American Physiological Society

Differential regional gene expression from cardiac dyssynchrony induced by chronic right ventricular free wall pacing in the mouse

Kenneth C. Bilchick1, Sudip K. Saha1, Ed Mikolajczyk3, Leslie Cope2, Will J. Ferguson4, Wayne Yu2, Steven Girouard3 and David A. Kass1

1 Division of Cardiology, Department of Medicine, School of Medicine, Baltimore, Maryland
2 Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, Maryland
3 Guidant Corporation, St. Paul, Minnesota
4 Agilent Technologies, Columbia, Maryland


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 GRANTS
 DISCLOSURES
 REFERENCES
 
Routine clinical right ventricular pacing generates left ventricular dyssynchrony manifested by early septal shortening followed by late lateral contraction, which, in turn, reciprocally stretches the septum. Dyssynchrony is disadvantageous to cardiac mechanoenergetics and worsens clinical prognosis, yet little is known about its molecular consequences. Here, we report the influence of cardiac dyssynchrony on regional cardiac gene expression in mice. Mice were implanted with a custom-designed miniature cardiac pacemaker and subjected to 1-wk overdrive right ventricular free wall pacing (720 beats/min, baseline heart rate 520–620 beats/min) to generate dyssynchrony (pacemaker: 3-V lithium battery, rate programmable, 1.5 g, bipolar lead). Electrical capture was confirmed by pulsed-wave Doppler and dyssynchrony by echocardiography. Gene expression from the left ventricular septal and lateral wall myocardium was assessed by microarray (dual-dye method, Agilent) using oligonucleotide probes and dye swap. Identical analysis was applied to four synchronously contracting controls. Of the 22,000 genes surveyed, only 18 genes displayed significant (P < 0.01) differential expression between septal/lateral walls >1.5 times that in synchronous controls. Gene changes were confirmed by quantitative PCR with excellent correlations. Most of the genes (n = 16) showed greater septal expression. Of particular interest were seven genes coding proteins involved with stretch responses, matrix remodeling, stem cell differentiation to myocyte lineage, and Purkinje fiber differentiation. One week of iatrogenic cardiac dyssynchrony triggered regional differential expression in relatively few select genes. Such analysis using a murine implantable pacemaker should facilitate molecular studies of cardiac dyssynchrony and help elucidate novel mechanisms by which stress/stretch stimuli due to dyssynchrony impact the normal and failing heart.

microarray; heart; activation timing


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
METHODS
 RESULTS
 DISCUSSION
 GRANTS
 DISCLOSURES
 REFERENCES
 
RECENT STUDIES have shown that dyssynchronous contraction of the left ventricle is a prominent and independent risk factor for worsened cardiovascular morbidity and mortality in patients with dilated heart failure (2). This pathophysiology occurs both from native conduction delay such as a left bundle branch block and artificial right ventricular pacing. Indeed, right ventricular pacing in patients who had reduced systolic function but were largely asymptomatic led to a greater incidence of worsening or new onset heart failure (26). Clinical studies employing biventricular stimulation (cardiac resynchronization therapy) to treat dyssynchrony have revealed significant benefits in both morbidity and mortality (3, 4).

Although the mechanical aspects of left ventricular dysfunction due to dyssynchrony have been well studied, the impact of dyssynchrony on molecular signaling remains ill defined. Studies have reported regional changes in calcium handling and stress kinase proteins as well as connexin 43, but these data reflect a small targeted sampling of potential changes that might occur (20). There have been no broad-based analyses of gene expression alterations from dyssynchrony. This has largely stemmed from the lack of a suitable animal model and, for clinical studies, the lack of appropriate regional tissue and difficulties in interpreting changes without adequate controls. Besides the human, the mammalian species most often utilized for genetic array analysis is the mouse. However, cardiac dyssynchrony in mice has not been previously studied, largely due to technical difficulties. To this end, we developed a custom miniature implantable mouse pacemaker capable of stimulating the murine heart at rates varying from 400 to 1,200 beats/min. In this study, we employed right ventricular free wall stimulation to generate cardiac dyssynchrony and then examined its effects on regional gene expression using differential microarray analysis.


   METHODS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
RESULTS
 DISCUSSION
 GRANTS
 DISCLOSURES
 REFERENCES
 
Miniature implantable mouse pacemaker.
Figure 1A shows the newly developed mouse pacemaker. The body of the pacemaker is 1.2 cm in diameter, weighs 1.5 g, and includes a 3-V lithium battery. The pacemaker is soldered to a 5-cm unipolar lead with a 1.75-turn solid platinum helix tip for tissue contact. A bipolar configuration is used to minimize thoracic muscle stimulation, with a 6-cm segment of 32-gauge insulated copper magnet wire soldered to the body and then wrapped around the main lead to terminate close to the distal helix. The pacemaker is painted with insulating material so that current flows between the helix and parallel wire rather than back to the pacemaker body via conductive tissues. To preserve battery life further, a resistor is connected in series with the helical lead. The pacemaker has four rate settings: 450, 550, 720, and 1,050 beats/min, with the rate adjusted by touching a magnet to the pacemaker body. Before implantation, the rate is set to 720 beats/min, and rate and output voltage are confirmed by oscilloscope.


Figure 1
View larger version (61K):
[in this window]
[in a new window]
  		Fig. 1. A: bipolar implantable mouse pacemaker compared with the size of a 19-gauge needle; B: mouse with pacemaker implanted in the abdomen (arrow).

 
Implant procedure.
The protocol was approved by the Johns Hopkins University Institutional Animal Care and Use Committee. Wild-type mice (C57Bl/6, 12 wk) were anesthetized with etomidate (10 mg/kg), intubated, and mechanically ventilated (6.7 µl/g at 120 breaths/min). Anesthesia was maintained with inhaled isoflurane (2%) while the electrocardiographic monitoring was performed. A ventral midline incision exposed the chest wall and abdomen, and abdominal subcutaneous tissue was dissected to create a pocket for the pacemaker. The right ventricular free wall was exposed by right anterolateral thoracotomy. After pericardial dissection, the pacemaker lead was advanced through the thoracotomy, placed perpendicular to the surface of the right ventricle, and fixed to the heart tissue by 1 revolutions of the distal screw lead. Capture was confirmed by electrocardiogram, and hemodynamic assessment (Fig. 2, A and B) was used to confirm stable mechanical function (Doppler aortic flow) at the 720 beats/min stimulation rate.


Figure 2
View larger version (87K):
[in this window]
[in a new window]
  		Fig. 2. Pulsed-wave Doppler aortic flow signal confirms the mechanical capture in conjunction with an electrocardiogram (ECG) showing right ventricular (RV) pacing.

 
The thoracotomy was closed with 6-0 Proline, and the site of lead entrance into the chest was sealed with glue to preserve an appropriate lead angle and position. The thorax was then evacuated by needle suction. After reconfirmation of capture by Doppler flow at varying pacing rates, the device was set to 720 beats/min. The pacemaker can was placed subcutaneously in the abdomen (Fig. 1B), and the skin closed with 5-0 silk. The animal was then allowed to recover. Successful implantation and capture for a period of at least 1 wk were achieved in 60% of mice.

Postoperative evaluation and terminal study.
Gene expression analysis was performed after 1 wk of pacing, a time when sustained capture was assured and documented by electrocardiographic and hemodynamic monitoring. At this time, animals (n = 4) were anesthetized and intubated, pacemaker capture was reconfirmed, and the heart was rapidly removed and washed in cold saline. The left ventricle was isolated and divided into septal and lateral wall halves that were further trimmed to provide septal and lateral free wall samples. The tissue was rapidly frozen in liquid nitrogen and stored for subsequent analysis. In addition to tissue from dyssynchronous mice, myocardium from normal controls (synchronous contraction, n = 4) was also obtained using the same procedure.

Physiological studies.
Chronic left ventricular dyssynchrony was documented by two-dimensional guided M-mode echocardiography (Sequoia C256, Siemens, 15-MHz linear array transducer) in several animals. In addition, the impact of right ventricular pacing-induced dyssynchrony on left ventricular chamber function was assessed by in vivo pressure-volume analysis (7) in 10 additional mice. For this assessment, anesthetized animals underwent a limited thoracotomy, after which a 1.4-Fr pressure-volume catheter A (SPR-719, Millar) was inserted into the heart via an apical stab and advanced to the aortic root. The catheter was interfaced with a custom-designed stimulator/analyzer, and pressure-volume data were recorded at 2 kHz for analysis.

RNA isolation and microarray design.
Total RNA was extracted with TRIzol reagent from left ventricular segments, and septal and lateral isolates from the four dyssynchronous mice were kept separate. RNA samples from the septal and lateral left ventricular walls of four synchronous control mice were pooled into a control septal and lateral sample. Functional genomic analysis was conducted on these 10 RNA samples (8 from dyssynchronous mice and 2 from control mice) with fluorophore reversal, such that each sample was assayed on two different microarrays. Corresponding septal and lateral samples from the same left ventricle were paired on the same microarray to achieve a direct comparison of the relative gene expression in different regions of the same heart.

Agilent Mouse Oligo microarray slides (G4121A, Agilent Technologies; Palo Alto, CA) containing >20,000 probes were used. The 60-mer oligonucleotide probes were oriented in the sense (5'–3') direction and spotted using Agilent's SurePrint fabrication technology, which utilizes an industrial-scale inkjet printer that synthesizes oligonucleotide probes in situ on glass wafers, which are then scribed onto bar-coded 1 x 3-in. glass slides. A complete probe list (G4121A) may be found online at http://www.chem.agilent.com/cag/bsp/oligoGL/011978_D_GeneList_20050310.html.

Microarray analysis.
Gene expression data were obtained using Agilent G2567AA Feature Extraction software, using defaults for all parameters except ratio terms, which were changed according to the Agilent protocol to fit the direct labeling procedure. Files and images, including error values and P values, were exported from the Agilent Feature Extraction software and loaded into Rosetta Resolver (version 3.2, build 3.2.2.0.33, Rosetta Biosoftware; Kirkland, WA). Four arrays for each sample pair, including fluorophore reversals, were combined into ratio experiments in Rosetta Resolver (21). Intensity plots were produced for each ratio experiment, and genes specifically output by this software were considered "signature genes" if P < 0.01. P values reflecting both microarray slide and biological variation were calculated using the Rosetta Resolver error model (21).

An alternate analysis was performed as follows. Agilent analysis was replaced with standard cDNA methods for within microarray normalization and background correction, and minor intermicroarray normalization was performed. Fluorophore swap pairs were averaged, and each gene was tested for differential expression using the significance analysis of microarrays (SAM) method (25).

PCR confirmation.
cDNA was synthesized from paced and pooled control RNA samples using TaqMan Reverse Transcription Reagents (Applied Biosystems). Real-time quantitative PCR (qPCR) was performed using TaqMan Universal PCR MasterMix and an ABI Prism 7700 Sequence Detector (Applied Biosystems) to confirm the results of the microarray. The following primer-probe mixes were used: dickkopf homolog 3 (dkk-3), matrilin-1 (COMP), myosin binding protein H (MyBP H), myosin regulatory light chain A, osteopontin, latent transforming growth factor-ß binding protein (LTBP)-2, and myosin binding protein C (MyBP C). The comparative cycle threshold method ({Delta}{Delta}Ct) was used to calculate septal cDNA expression relative to lateral cDNA expression, which was normalized using GAPDH cDNA expression for each sample. Paced and pooled control septal-to-lateral fold changes were then compared.

Sham pacemaker study.
To rule out effects of the surgical pacemaker implantation itself on regional gene expression, sham pacemakers were constructed that were identical to the functional pacemakers except that the battery was insulated from the attached pacemaker lead. These devices were then implanted in four additional mice (C57/Bl6, 12 wk) using the same surgical techniques as in the active-pacing animals. One week after the surgery, hearts were harvested in an identical manner, and qPCR was performed with the same seven probes listed above with a GAPDH probe for normalization. Regional expression for each gene was contrasted to mice with functional pacemakers and the pooled control sample.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
DISCUSSION
 GRANTS
 DISCLOSURES
 REFERENCES
 
Dyssynchrony in the intact mouse.
Figure 3 shows left ventricular dyssynchrony induced by right ventricular free wall pacing and assessed by M-mode echocardiography. Also shown for comparison is the M-mode echocardiogram in a mouse with normal contraction, showing the septal and lateral left ventricular walls contracting simultaneously. This would be expected with normal sinus rhythm or atrial pacing because the pacing impulse from the atrium is conducted through the atrioventricular node and the ventricles are activated simultaneously. In contrast, septal contraction was earlier in the left ventricles with right ventricular free wall pacing. The corresponding electrocardiograms from mice with atrial pacing and right ventricular pacing are also reproduced in Fig. 3.


Figure 3
View larger version (81K):
[in this window]
[in a new window]
  		Fig. 3. ECG and M-mode echocardiogram (Echo) in the mouse with atrial pacing versus RV free wall pacing. Dyssynchrony is demonstrated in the mouse with RV free wall pacing with early septal shortening and late lateral shortening (arrows).

 
Figure 4 shows an example of pressure-volume loops for normal sinus rhythm and right ventricular free wall pacing in the mouse, revealing a reduction in overall left ventricular function due to dyssynchrony. Compared with atrial pacing, right ventricular free wall stimulation lowered the mean peak rate of pressure rise (dP/dtmax) by 14 ± 8% (P = 0.001), stroke volume by 19 ± 13% (P = 0.01), and stroke work by 22 ± 11% (P = 0.005). The heart weights of mice after 2 wk of right ventricular free wall pacing were similar to those of controls.


Figure 4
View larger version (16K):
[in this window]
[in a new window]
  		Fig. 4. Pressure-volume loops in the mouse with a pacemaker implanted in the RV (RVP) compared with those in a mouse in normal sinus rhythm (NSR).

 
Microarray analysis.
The full dataset is MIAME compliant and may be accessed at the National Center for Biotechnology Information Gene Expression Omnibus (http://www.ncbi.nlm.nih.gov/geo/submission/geosubmi.cgi). RNA isolated from all hearts was analyzed by spectrophotometry and found to be of high quality. Of the >20,000 genes studied, the Agilent analysis revealed only 18 genes with significant (P < 0.01) differential expression between the left ventricular septal and lateral walls of a magnitude of 1.5-fold or greater, each being normalized for corresponding regional disparities (if any) in control synchronous hearts (Table 1). By the SAM method with a false discovery rate of 21% and a 1.5-fold threshold, 10 significant genes were identified, most of them among the original 18 already identified. The vast majority (16/18) of the genes identified by the Agilent method had septal expression increased over lateral expression.


View this table:
[in this window]
[in a new window]
  		Table 1. Significant genes in dyssynchronous hearts compared with synchronous control hearts

 
Relative changes in gene expression for the seven genes with prominent disparities identified by the Agilent method were confirmed by qPCR, and excellent correlations were obtained between qPCR and Agilent analysis for all genes tested (Table 2). Regional expression changes for dkk-3, myosin regulatory light chain A, matrilin-1, and MyBP H were greater than 5-fold by qPCR, whereas changes of 3.7-, 2.4-, and 1.6-fold were observed for osteopontin, LTBP-2, and MyBP C, respectively. These seven genes were also of particular interest due to their potential impact on cardiac structure and function. They included genes coding proteins involved with myocardial stretch response (matrilin-1 and osteopontin), matrix remodeling (matrilin-1, osteopontin, and LTBP-2), stem cell differentiation to myocyte lineage (dkk-3), and Purkinje fiber differentiation (MyBP H). As shown in Table 2, differential expression for most genes was the result of both an increase in septal expression and a decrease in lateral wall expression (compared with the synchronous pooled septal and lateral left ventricular samples). Such analysis was possible because gene expression by qPCR was measured relative to the housekeeping gene GAPDH.


View this table:
[in this window]
[in a new window]
  		Table 2. Subset of significant PCR-confirmed genes in dyssynchronous hearts after normalization to synchronous controls

 
As shown in Table 3, regional gene expression ratios as measured by qPCR in mice with sham pacemakers implanted in the right ventricle (n = 4) were close to unity and thus similar to that obtained in the pooled control sample. Regional expression ratios in dyssynchronous right ventricular free wall-paced mice (shown here without normalization to the pooled control) were statistically different from the sham results.


View this table:
[in this window]
[in a new window]
  		Table 3. Direct comparison of significant genes in mice with functional and nonfunctional pacemakers implanted in the RV

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
GRANTS
 DISCLOSURES
 REFERENCES
 
We developed a new experimental system for the study of spatial and temporal gene expression changes in the presence of mechanical dyssynchrony. By combining a novel miniature murine implantable pacemaker to create programmable dyssynchrony and microarray/PCR methods for quantifying regional gene expression, we demonstrated prominent regional changes in gene expression between the lateral and septal left ventricular walls. The genes that showed significant regional expression heterogeneity (a relatively small number compared with the total number of genes tested) are involved in important processes such as matrix remodeling, stem cell differentiation, myocardial stress responses, and hypertrophy.

Cardiac dyssynchrony, whether due to a left bundle branch block or iatrogenically induced by right ventricular free wall pacing, induces regional changes in mechanical function, loading, and metabolic requirements for the myocardium. Early shortening occurs in the septum, leading to greater prestretch (preload) in the lateral wall. Late shortening of the lateral wall occurs at somewhat higher stress but also leads to systolic rightward stretch of the septum. Studies have revealed corresponding acute increases in lateral versus septal perfusion and glucose metabolism. In a canine model of heart failure with dyssynchrony, we found regional protein expression of calcium-handling proteins [sarco(endo)plasmic reticular Ca2+-ATPase and phospholamban] and gap junction protein connexin 43 to be lower in the lateral wall than the septal wall, whereas the stress response MAPK (ERK1/2) was enhanced (20). However, this was not observed in dyssynchronous nonfailing hearts (19). The present model is closer to the latter condition, and our results point to different signaling such that the septal stretch may be more significant to localizing gene expression than lateral loading in this setting.

Importantly, there have been no prior systematic broad surveys of the molecular changes associated with dyssynchrony. A remarkable aspect of our findings is that only ~0.1% of the 22,000 genes assayed (representing nearly all the presently characterized and named genes in the mouse genome) revealed significant regional changes relative to synchronous controls. Among these, several had changes of greater than fivefold by qPCR. We were able to rule out that these regional changes were due to intrinsic differences between septum and lateral walls by employing pooled synchronous controls in the analysis. The expression ratio therefore represents the ratio of expression in lateral versus septal walls for dyssynchronous hearts normalized to the same ratio in synchronous hearts. For most of the significant genes, the synchronous heart regional ratios were very close to unity. The lack of significant changes in many genes was not due to marked scatter among individual samples but rather to consistent minimal differences in expression. This finding indicates that there was a high level of signal relative to noise and that targeted signaling is involved.

The broad functions of differentially expressed genes included stretch responses, matrix remodeling, stem cell differentiation to myocyte lineage, and Purkinje fiber differentiation.

Among them was osteopontin, which belongs to a family of matricellular proteins that are important for helping the heart respond to hemodynamic stress by modulating cell function and cell-matrix interactions (16). Osteopontin is regulated by Akt kinase (28) and is primarily expressed by cardiomyocytes in the heart (8). It modulates myocardial hypertrophy in response to chronic pressure overload in mice (27), promoting fibrosis by protecting cardiac fibroblasts from cell death (29). It is also involved in vascular remodeling, inflammation, and lipid metabolism (22). Osteopontin-deficient mice have exaggerated left ventricular dilation and reduced collagen deposition after a myocardial infarction, further suggesting that osteopontin has a beneficial effect on left ventricular remodeling in animals coping with stress (24).

Another differentially expressed gene was matrilin-1. Matrilins are involved in matrix remodeling and response to stress. Matrilin-1, formerly known as cartilage oligomeric matrix protein (13), contains von Willebrand factor A and EGF domains, can form filamentous networks with or without collagen and is first expressed in the mouse ventricular myocardium and endocardium during the second week postconception (17).

Heterogeneous expression of LTBP-2 was also observed. LTBPs belong to the fibrillin-LTBP family of extracellular matrix proteins and are important for the appropriate secretion and folding of tissue growth factor-ß proteins. They are potent regulators of extracellular matrix formation with important immunomodulatory and regulatory roles for cell growth (15).

Dkk-3 was differentially expressed with upregulation in the septum and downregulation in the lateral free wall of dyssynchronous left ventricles. The dkk family of genes, originally studied in Xenopus embryogenesis, inhibit Wnt signaling (12). Dkk-3 is expressed in many adult tissues, including the ventricular myocardium. The related protein dkk-1 plays an important role in adult stem cell proliferation through Wnt-5a antagonism (9, 10), suggesting another possible influence of this family of genes on cardiac growth and differentiation.

Two MyBPs, MyBP H and MyBP C, also had significant differences in regional gene expression. Interestingly, recent experiments in chicken hearts have shown that skeletal muscle-specific MyBP H is present exclusively in myofibril bands within Purkinje fibers (1), and its upregulation may be in response to the altered stimulation timing. MyBP C, a thick filament-associated protein localizing to the cross-bridge-containing C zones of striated muscle sarcomeres, is a substrate of cAMP kinase and plays an important role in the regulation of cross-bridge cycling and contraction (6). Clinical interest in C protein is due, in part, to mutations in this protein associated with hypertrophic cardiomyopathy.

Finally, significant regional differences in the expression of regulatory myosin light chain A were observed. Both regulatory and essential myosin light chain A are expressed in the left ventricle during development but are only expressed in adult left ventricles in the presence of heart disease. For example, left ventricular expression of essential myosin light chain A has been shown to increase in hearts with left ventricular hypertrophy (14) and decrease after surgical reduction of aortic stenosis in pressure-loaded hearts (23). Reconstitution of the protein with ventricular myosin increases actin-activated myosin ATPase activity, suggesting that contractility may be improved in vivo (11). Persistent left ventricular expression of regulatory myosin light chain A has been described in mice deficient in the retinoid X receptor-{alpha} (5). Decreased ventricular expression of regulatory myosin light chain A is thought to be due to repressed transcription, although the exact mechanism is unclear. The regulatory myosin light chain A promoter has binding sites for myocyte enhancer factor 2A, GATA-binding protein 4, serum response factor, and retinoic acid, so there are many possible candidates for reactivation (18). The septal/lateral wall disparities consistently observed in dyssynchronous mice but not in synchronous mice make atrial contamination unlikely.

Several limitations of this study should be noted. The present pacemakers are not constant-current devices. As a result, any short circuiting that might form due to fibrosis or fluid can drain the battery. We initially tried longer pacing periods but found that pacing capture was less predictable after 10–14 days. Thus our model is one of the early changes occurring in cardiac dyssynchrony without overt heart failure. Longer-term dyssynchrony and dyssynchrony superimposed on a failing heart could well involve more and different genes. Moreover, although a mouse model of dyssynchrony has advantages, including tight control over genetic background, improved signal-to-noise ratios in studying expression responses, and a potential to use transgenic and knockout models, it does not necessarily reflect dyssynchrony responses for a human heart.

In conclusion, cardiac dyssynchrony, itself, induces regional changes in gene expression that are consistent with early stages of cardiac remodeling. The present study serves to establish the feasibility of such studies, highlights novel genes involved in regional changes in activation timing, and indicates the apparent role of late septal systolic stretch in this behavior. Whether the spatial patterns of gene expression are sustained over longer periods of dyssynchrony, are accompanied by additional changes, and are altered by states of cardiac failure states remains the focus of ongoing investigations.


   GRANTS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 GRANTS
DISCLOSURES
 REFERENCES
 
This study was supported by National Heart, Lung, and Blood Institute Grants T32-HL-07227, PO1-HL-077180, and PO1-HL-59408 (to D. A. Kass), a grant from the Guidant Corporation, and the Abraham and Virginia Weiss Professorship (to D. A. Kass).


   DISCLOSURES
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 GRANTS
 DISCLOSURES
REFERENCES
 
D. A. Kass is a consultant and scientific advisory board member for the Guidant Corporation. S. Girouard and E. Mikolajczyk are employees of Guidant Corporation.


   ACKNOWLEDGMENTS
 
The authors thank Drs. Eiki Takimoto and Hunter Champion for the technical assistance in this project.


   FOOTNOTES
 
Article published online before print. See website for date of publication (http://physiolgenomics.physiology.org).

Address for reprint requests and other correspondence: D. A. Kass, Dept. of Medicine, Johns Hopkins Univ. School of Medicine, Ross Bldg. 835, 720 Rutland Ave., Baltimore, MD 21205 (e-mail: dkass{at}jhmi.edu).


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 GRANTS
 DISCLOSURES
 REFERENCES
 

  1. Alyonycheva T, Cohen-Gould L, Siewert C, Fischman DA, and Mikawa T. Skeletal muscle-specific myosin binding protein-H is expressed in Purkinje fibers of the cardiac conduction system. Circ Res 80: 665–672, 1997.[Abstract/Free Full Text]
  2. Baldasseroni S, De Biase L, Fresco C, Marchionni N, Marini M, Masotti G, Orsini G, Porcu M, Pozzar F, Scherillo M, and Maggioni AP. Cumulative effect of complete left bundle-branch block and chronic atrial fibrillation on 1-year mortality and hospitalization in patients with congestive heart failure. A report from the Italian network on congestive heart failure (in-CHF database). Eur Heart J 23: 1692–1698, 2002.[Abstract/Free Full Text]
  3. Bristow MR, Saxon LA, Boehmer J, Krueger S, Kass DA, De Marco T, Carson P, DiCarlo L, DeMets D, White BG, DeVries DW, and Feldman AM. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure. N Engl J Med 350: 2140–2150, 2004.[Abstract/Free Full Text]
  4. Cleland JG, Daubert JC, Erdmann E, Freemantle N, Gras D, Kappenberger L, and Tavazzi L. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med 352: 1539–1549, 2005.[Abstract/Free Full Text]
  5. Dyson E, Sucov HM, Kubalak SW, Schmid-Schonbein GW, DeLano FA, Evans RM, Ross J Jr, and Chien KR. Atrial-like phenotype is associated with embryonic ventricular failure in retinoid X receptor alpha–/– mice. Proc Natl Acad Sci USA 92: 7386–7390, 1995.[Abstract/Free Full Text]
  6. Flashman E, Redwood C, Moolman-Smook J, and Watkins H. Cardiac myosin binding protein C: its role in physiology and disease. Circ Res 94: 1279–1289, 2004.[Abstract/Free Full Text]
  7. Georgakopoulos D and Kass D. Minimal force-frequency modulation of inotropy and relaxation of in situ murine heart. J Physiol 534: 535–545, 2001.[Abstract/Free Full Text]
  8. Graf K, Do YS, Ashizawa N, Meehan WP, Giachelli CM, Marboe CC, Fleck E, and Hsueh WA. Myocardial osteopontin expression is associated with left ventricular hypertrophy. Circulation 96: 3063–3071, 1997.[Abstract/Free Full Text]
  9. Gregory CA, Singh H, Perry AS, and Prockop DJ. The Wnt signaling inhibitor dickkopf-1 is required for reentry into the cell cycle of human adult stem cells from bone marrow. J Biol Chem 278: 28067–28078, 2003.[Abstract/Free Full Text]
  10. Horwitz EM. Dkk-1-mediated expansion of adult stem cells. Trends Biotechnol 22: 386–388, 2004.[CrossRef][ISI][Medline]
  11. Khalina YN, Bartsch H, Petzhold D, Haase H, Podlubnaya ZA, Shpagina MD, and Morano I. Reconstitution of ventricular myosin with atrial light chains-1 improves its functional properties. Acta Biochim Pol 2005.
  12. Monaghan AP, Kioschis P, Wu W, Zuniga A, Bock D, Poustka A, Delius H, and Niehrs C. Dickkopf genes are co-ordinately expressed in mesodermal lineages. Mech Dev 87: 45–56, 1999.[CrossRef][ISI][Medline]
  13. Paulsson M and Heinegard D. Matrix proteins bound to associatively prepared proteoglycans from bovine cartilage. Biochem J 183: 539–545, 1979.[ISI][Medline]
  14. Ritter O, Luther HP, Haase H, Baltas LG, Baumann G, Schulte HD, and Morano I. Expression of atrial myosin light chains but not alpha-myosin heavy chains is correlated in vivo with increased ventricular function in patients with hypertrophic obstructive cardiomyopathy. J Mol Med 77: 677–685, 1999.[CrossRef][ISI][Medline]
  15. Saharinen J, Hyytiainen M, Taipale J, and Keski-Oja J. Latent transforming growth factor-beta binding proteins (LTBPs)–structural extracellular matrix proteins for targeting TGF-beta action. Cytokine Growth Factor Rev 10: 99–117, 1999.[CrossRef][ISI][Medline]
  16. Schellings MW, Pinto YM, and Heymans S. Matricellular proteins in the heart: possible role during stress and remodeling. Cardiovasc Res 64: 24–31, 2004.[Abstract/Free Full Text]
  17. Segat D, Frie C, Nitsche PD, Klatt AR, Piecha D, Korpos E, Deak F, Wagener R, Paulsson M, and Smyth N. Expression of matrilin-1, -2 and -3 in developing mouse limbs and heart. Matrix Biol 19: 649–655, 2000.[CrossRef][ISI][Medline]
  18. Small EM and Krieg PA. Molecular regulation of cardiac chamber-specific gene expression. Trends Cardiovasc Med 14: 13–18, 2004.[CrossRef][ISI][Medline]
  19. Spragg DD, Akar FG, Helm RH, Tunin RS, Tomaselli GF, and Kass DA. Abnormal conduction and repolarization in late-activated myocardium of dyssynchronously contracting hearts. Cardiovasc Res 67: 77–86, 2005.[Abstract/Free Full Text]
  20. Spragg DD, Leclercq C, Loghmani M, Faris OP, Tunin RS, DiSilvestre D, McVeigh ER, Tomaselli GF, and Kass DA. Regional alterations in protein expression in the dyssynchronous failing heart. Circulation 108: 929–932, 2003.[Abstract/Free Full Text]
  21. Stoughton R and Dai H. USPTO Patent Full-Text and Image Database. Statistical Combining of Cell Expression Profiles. US Patent No. 6351712 (online). http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6351712.PN.&OS=PN/6351712&RS=PN/6351712 [22 May 2006].
  22. Strom A, Franzen A, Wangnerud C, Knutsson AK, Heinegard D, and Hultgardh-Nilsson A. Altered vascular remodeling in osteopontin-deficient atherosclerotic mice. J Vasc Res 41: 314–322, 2004.[CrossRef][ISI][Medline]
  23. Sutsch G, Brunner UT, von Schulthess C, Hirzel HO, Hess OM, Turina M, Krayenbuehl HP, and Schaub MC. Hemodynamic performance and myosin light chain-1 expression of the hypertrophied left ventricle in aortic valve disease before and after valve replacement. Circ Res 70: 1035–1043, 1992.[Abstract/Free Full Text]
  24. Trueblood NA, Xie Z, Communal C, Sam F, Ngoy S, Liaw L, Jenkins AW, Wang J, Sawyer DB, Bing OH, Apstein CS, Colucci WS, and Singh K. Exaggerated left ventricular dilation and reduced collagen deposition after myocardial infarction in mice lacking osteopontin. Circ Res 88: 1080–1087, 2001.[Abstract/Free Full Text]
  25. Tusher VG, Tibshirani R, and Chu G. Significance analysis of microarrays applied to the ionizing radiation response. Proc Natl Acad Sci USA 98: 5116–5121, 2001.[Abstract/Free Full Text]
  26. Wilkoff BL, Cook JR, Epstein AE, Greene HL, Hallstrom AP, Hsia H, Kutalek SP, and Sharma A. Dual-chamber pacing or ventricular backup pacing in patients with an implantable defibrillator: the Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial. JAMA 288: 3115–3123, 2002.[Abstract/Free Full Text]
  27. Xie Z, Singh M, and Singh K. Osteopontin modulates myocardial hypertrophy in response to chronic pressure overload in mice. Hypertension 44: 826–831, 2004.[Abstract/Free Full Text]
  28. Zhang G, He B, and Weber GF. Growth factor signaling induces metastasis genes in transformed cells: molecular connection between Akt kinase and osteopontin in breast cancer. Mol Cell Biol 23: 6507–6519, 2003.[Abstract/Free Full Text]
  29. Zohar R, Zhu B, Liu P, Sodek J, and McCulloch CA. Increased cell death in osteopontin-deficient cardiac fibroblasts occurs by a caspase-3-independent pathway. Am J Physiol Heart Circ Physiol 287: H1730–H1739, 2004.[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 EuropaceHome page
A. Auricchio and F. W. Prinzen
Update on the pathophysiological basics of cardiac resynchronization therapy
Europace, July 1, 2008; 10(7): 797 - 800.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
26/2/109    most recent
00281.2005v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bilchick, K. C.
Right arrow Articles by Kass, D. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bilchick, K. C.
Right arrow Articles by Kass, D. A.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online
Copyright © 2006 by the American Physiological Society.