Regional heterogeneity in gene expression profiles: a transcript analysis in human and rat heart.
BACKGROUND
Investigations involving biopsies of human cardiac tissue often assume that myocardial samples from a specific location are representative of the entire heart.


OBJECTIVE
There are significant regional differences in gene expression in the heart.


METHODS
We used two models. In the first model, seven whole human hearts were cut in 1-cm slices from apex to base and 11 distinct regions were sampled. Full thickness left ventricular tissue was further subdivided equally into an inner, outer, and middle region. In the second model, hearts were removed from adult Sprague-Dawley rats and were divided into 4 regions. Using species-specific quantitative reverse transcriptase-polymerase chain reaction, we measured transcript levels of myosin heavy chain beta (MHC-beta), glucose transporter 1 (GLUT 1), and atrial natriuretic factor (ANF) in tissue samples from both models.


RESULTS
In human heart, there were significant differences in transcript levels between regions. The following patterns could be recognized among the seven hearts. ANF expression was highest in the subendocardial region. MHC-beta and GLUT 1 transcript levels were higher in the right ventricle than the left ventricle. As expected, ANF transcript levels were highest in the atria, where MHC-beta and GLUT 1 expression was low. Analogous to the human studies, MHC-beta and GLUT 1 transcript levels were low in rat atria as compared to ventricles. In rat heart, MHC-beta expression was higher in the left ventricle than the right ventricle while GLUT 1 expression was not significantly different between ventricles.


CONCLUSIONS
Despite the large variability in transcript levels among different regions in human hearts, certain patterns in gene expression emerged suggesting that different anatomical regions of the heart also differ in respect to gene expression.
Sharma
Saumya
S
Division of Cardiology, University of Texas-Houston Medical School, 6431 Fannin, Houston, TX 77030, USA.
Razeghi
Peter
P
Shakir
Ali
A
Keneson
Bradley J
BJ
Clubb
Fred
F
Taegtmeyer
Heinrich
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D018740:Genetic Heterogeneity; D014644:Genetic Variation / Q000235:genetics; D051272:Glucose Transporter Type 1; D006325:Heart Atria / Q000737:chemistry / Q000378:metabolism; D006352:Heart Ventricles / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis / Q000235:genetics; D018995:Myosin Heavy Chains / Q000096:biosynthesis / Q000235:genetics; D024501:Nonmuscle Myosin Type IIB; D051381:Rats; D017207:Rats, Sprague-Dawley
D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; C495677:SLC2A1 protein, human; C495679:Slc2a1 protein, rat; D009320:Atrial Natriuretic Factor; D024501:Nonmuscle Myosin Type IIB; C103815:nonmuscle myosin type IIB heavy chain; D018995:Myosin Heavy Chains