scholarly journals Preproenkephalin mRNA expression in developing rat heart and in cultured ventricular cardiac muscle cells

1989 ◽  
Vol 258 (1) ◽  
pp. 73-78 ◽  
Author(s):  
J P Springhorn ◽  
W C Claycomb
Keyword(s):  
Cardiac Muscle ◽  
Cell Cultures ◽  
Translational Regulation ◽  
Muscle Cells ◽  
Heart Cell ◽  
Developmentally Regulated ◽  
Adult Rats ◽  
Cardiac Muscle Cells ◽  
Adult Rat ◽  
Developing Rat

Heart muscle tissue has previously been reported to have the highest content of preproenkephalin (ppEnk) mRNA of any tissue in the adult rat. We have determined that it is present in the ventricular cardiac muscle cells of the heart and is developmentally regulated. The expression of ppEnk mRNA was observed to be low throughout the first 2 weeks of postnatal development and decreases substantially during week 3. Expression was again low by week 4, but by adulthood (approx. 3 months), it reached a maximum. ppEnk mRNA was actively expressed in primary cardiac muscle cell cultures prepared from both neonatal and adult rats. Its steady-state content in cell cultures was observed to be increased by cyclic AMP and 3-isobutyl-1-methylxanthine. The phorbol ester phorbol 12-myristate 13-acetate elicited a transient effect (i.e. an increase was observed at 4 h and a return to control values by 24 h). We speculate that enkephalin may play a multi-functional role in the differentiation of neonatal cardiac muscle cells and in the terminally differentiated adult heart cell. We demonstrate that the primary culture systems employed in this study will be useful models with which to explore both transcriptional and translational regulation of ppEnk mRNA in the heart.

scholarly journals Proto-oncogene expression in proliferating and differentiating cardiac and skeletal muscle

1987 ◽  
Vol 247 (3) ◽  
pp. 701-706 ◽  
Author(s):  
W C Claycomb ◽  
N A Lanson
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Muscle Tissue ◽  
Cellular Proliferation ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Specific Cell ◽  
Adult Rats ◽  
Cardiac Muscle Cells ◽  
Oncogene Expression

We have examined the expression of 13 proto-oncogenes in proliferating and terminally differentiated cardiac and skeletal muscle. Total RNA was prepared from intact ventricular cardiac-muscle tissue and from purified ventricular cardiac-muscle cells of neonatal and adult rats and from cultured proliferating and terminally differentiated L6A1 rat skeletal-muscle cells. cDNA probes for histone H4, thymidine kinase, myosin heavy chain and M-creatine kinase were used to assess cellular proliferation and differentiation. Oncogenes c-myc, c-raf, c-erb-A, c-ras-H, c-ski, and c-sis were expressed in both proliferating and differentiated cardiac muscle tissue and cells, whereas c-myb expression was not observed in either. c-src was expressed only in neonatal cardiac muscle tissue and cells. c-fms, c-abl, and c-ras-K were expressed in tissue from both neonatal and adult animals but only in purified cells from neonatal animals. c-fes/fps was expressed only in neonatal cardiac muscles cells. c-fos expression was not observed in cardiac-muscle tissue from either neonatal or adult rats, but surprisingly was abundantly expressed in freshly isolated cardiac-muscle cells from animals of both ages. These results emphasize that biochemical analysis using intact cardiac-muscle tissue may not necessarily reflect muscle-specific cell processes. They also show that the expression of c-fos can be activated by the cell isolation procedure. c-myc, c-ski, c-ras-H, c-ras-K, c-abl, c-raf and c-erb-A were expressed in both proliferating and terminally differentiated skeletal-muscle cells, whereas c-myb, c-fos, c-src and c-fms transcripts were observed only in proliferating cells. c-fes/fps and c-sis were not expressed in dividing or fused skeletal-muscle cells. These results demonstrate unique tissue and cell-specific patterns of proto-oncogene expression and suggest that these genes may be involved with the regulation of cellular proliferation and terminal differentiation in striated muscle.

scholarly journals Proliferating cell nuclear antigen in developing and adult rat cardiac muscle cells.

1991 ◽  
Vol 69 (5) ◽  
pp. 1353-1360 ◽  
Author(s):  
T A Marino ◽  
S Haldar ◽  
E C Williamson ◽  
K Beaverson ◽  
R A Walter ◽  
...  
Keyword(s):  
Cardiac Muscle ◽  
Proliferating Cell Nuclear Antigen ◽  
Muscle Cells ◽  
Nuclear Antigen ◽  
Cardiac Muscle Cells ◽  
Adult Rat ◽  
Proliferating Cell

Translation of heart preproenkephalin mRNA and secretion of enkephalin peptides from cultured cardiac myocytes

1992 ◽  
Vol 263 (5) ◽  
pp. H1560-H1566 ◽  
Author(s):  
J. P. Springhorn ◽  
W. C. Claycomb
Keyword(s):  
Cardiac Muscle ◽  
Muscle Cells ◽  
Neonatal Rat ◽  
Ribonuclease Protection Assay ◽  
Cardiac Muscle Cells ◽  
Adult Rat ◽  
Rabbit Reticulocyte Lysate System ◽  
Ribonuclease Protection ◽  
Carboxy Terminal

Rat ventricular cardiac muscle has previously been shown to contain exceptionally high levels of preproenkephalin mRNA (ppEnk mRNA). We have recently determined that the level of ppEnk mRNA is developmentally and hormonally regulated in rat ventricular cardiac muscle tissue and in cultured myocytes (J. P. Springhorn and W. C. Claycomb. Biochem. J. 258: 73-77, 1989). We demonstrate in the current study that heart ppEnk mRNA is structurally identical at the 5' end to brain ppEnk mRNA using a ribonuclease protection assay and that heart ppEnk mRNA can be translated in vitro using a rabbit reticulocyte lysate system. In vitro synthesized preproenkephalin peptides were immunoprecipitated with a polyclonal antibody directed to the carboxy-terminal seven amino acids of preproenkephalin. We have also established by radioimmunoassay that enkephalin-containing peptides are secreted from cultured neonatal and adult rat ventricular cardiac muscle cells. This secretion is linear with respect to time and can be stimulated by phorbol 12-myristate 13-acetate (PMA) and adenosine 3',5'-cyclic monophosphate (cAMP). It was determined by column chromatography that cAMP induced neonatal rat ventricular cardiac muscle cells to secrete Met5-enkephalin-Arg6-Phe7, whereas PMA plus 3-isobutyl-1-methylxanthine induced adult rat ventricular cardiac muscle cells to secrete Met5-enkephalin. These studies establish that ventricular heart muscle ppEnk mRNA can be translated and that enkephalin peptides are secreted from ventricular cardiac muscle cells.

Ultrastructure of cultured atrial cardiac muscle cells from adult rats

1984 ◽  
Vol 171 (2) ◽  
pp. 191-206 ◽  
Author(s):  
R. L. Moses ◽  
William C. Claycomb
Keyword(s):  
Cardiac Muscle ◽  
Muscle Cells ◽  
Adult Rats ◽  
Cardiac Muscle Cells
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