CLONING GENES THAT REGULATE MYOCARDIOCYTE PROLIFERATION

Project: Research project

Description

Growth of cardiac myocytes is traditionally divided into two categories;
namely the increase in cell numbers which is observed during embryonic
development (hyperplastic growth), and the increase in cell mass which is
observed during neonatal life (hypertrophic growth). The gene products
which regulate these different types of myocardiocyte growth remain largely
uncharacterized. The experiments in this proposal are designed to identify
and clone gene which regulate proliferation in myocardiocytes. the
experiments are based on a transgenic model system in which expression of
the SV40 large T antigen oncogene was targeted to the cardiac atria with
the Atrial Natriuretic Factor promoter. The transgenic mice develop
unilateral right atrial hyperplasia; the hyperplastic atria are comprised
of differentiated, dividing myocytes. This model demonstrates that adult
myocardiocytes can re-enter the cell cycle in response to viral oncogene
expression. Further analysis of the transgenic mice has revealed several
properties which provide experimental inroads to identify and clone other
genes which control observations. Specifically, we will: 1) Identify and
clone the gene which promotes constitutive myocardiocyte hyperplasia in the
transgenic model. A genetic variant has been identified which is able to
complement T antigen and induce constitutive hyperplasia in atrial
myocytes. A combination of genetic and molecular approaches is proposed to
identify and clone this gene. 2) characterize the growth requirements of
myocardiocytes in culture. We have generated a putative cardiac cell line
derived from the transgenic tissue. These myocardiocytes divide rapidly in
culture, retain a highly differentiated cardiocyte phenotype, can be
repeatedly passaged, and exhibit spontaneous electrical and contractile
activities. Clone genes which, when altered, produce a hyperplastic
response in transgenic myocardiocytes. Atrial hyperplasia in the
transgenic model can follow a pattern which is dependent upon stocastic
genetic alterations (mutations). We propose to use a variation of standard
oncogene transfection studies to clone the genes which facilitate a
hyperplastic response. 4) Identify the array of genes which are expressed
specifically in proliferating myocardiocytes. We will perform
comprehensive screens to identify gene products who's expression is
specifically induced (or repressed) during myocardiocyte proliferation. 5)
Further develop second transgenic model system in which T antigen is
targeted to cardiac myocytes with the alpha-Myosin Heavy Chain promoter.
Initial experiments indicated that ventricular myocytes can also exhibit a
hyperplastic response to T antigen. We will characterize ventricular
hyperplasia in this new model, and further we will apply the approaches
described above to this new system. These experiments will help resolve a
fundamental question in cardiology; namely what genes regulate
myocardiocyte growth. Once these genes are identified, studies aimed at
assessing stimuli (hormonal or chemical) which mediate their expression may
ultimately provide a therapeutic basis for myocardiocyte regeneration in
vivo.
StatusFinished
Effective start/end date7/1/903/31/08

Funding

  • National Institutes of Health: $374,911.00
  • National Institutes of Health: $374,950.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $337,639.00
  • National Institutes of Health: $334,568.00
  • National Institutes of Health
  • National Institutes of Health: $353,669.00
  • National Institutes of Health: $344,412.00
  • National Institutes of Health: $374,988.00
  • National Institutes of Health
  • National Institutes of Health: $323,120.00
  • National Institutes of Health: $325,732.00
  • National Institutes of Health
  • National Institutes of Health: $237,044.00
  • National Institutes of Health: $290,441.00
  • National Institutes of Health: $366,061.00

Fingerprint

Organism Cloning
Cardiac Myocytes
Genes
Transgenic Mice
Viral Tumor Antigens
Growth
Clone Cells
Proteins
Polyomavirus Transforming Antigens
Hyperplasia
Cell Cycle
Tuberous Sclerosis
Oncogene Proteins
Carrier Proteins
Neoplasms
Muscle Cells
Phenotype
Therapeutics
Cell Division
Ventricular Myosins

ASJC

  • Medicine(all)