scholarly journals A hormone-encoding gene identifies a pathway for cardiac but not skeletal muscle gene transcription.

1994 ◽  
Vol 14 (5) ◽  
pp. 3115-3129 ◽  
Author(s):  
C Grépin ◽  
L Dagnino ◽  
L Robitaille ◽  
L Haberstroh ◽  
T Antakly ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Regulatory Elements ◽  
Cardiac Cells ◽  
Skeletal Myocytes ◽  
Encoding Gene ◽  
Muscle Gene ◽  
Encoding Genes ◽  
Dependent Pathway ◽  
Gata Gene

In contrast to skeletal muscle, the mechanisms responsible for activation and maintenance of tissue-specific transcription in cardiac muscle remain poorly understood. A family of hormone-encoding genes is expressed in a highly specific manner in cardiac but not skeletal myocytes. This includes the A- and B-type natriuretic peptide (ANP and BNP) genes, which encode peptide hormones with crucial roles in the regulation of blood volume and pressure. Since these genes are markers of cardiac cells, we have used them to probe the mechanisms for cardiac muscle-specific transcription. Cloning and functional analysis of the rat BNP upstream sequences revealed unexpected structural resemblance to erythroid but not to muscle-specific promoters and enhancers, including a requirement for regulatory elements containing GATA motifs. A cDNA clone corresponding to a member of the GATA family of transcription factors was isolated from a cardiomyocyte cDNA library. Transcription of this GATA gene is restricted mostly to the heart and is undetectable in skeletal muscle. Within the heart, GATA transcripts are localized in ANP- and BNP-expressing myocytes, and forced expression of the GATA protein in heterologous cells markedly activates transcription from the natural cardiac muscle-specific ANP and BNP promoters. This GATA-dependent pathway defines the first mechanism for cardiac muscle-specific transcription. Moreover, the present findings reveal striking similarities between the mechanisms controlling gene expression in hematopoietic and cardiac cells and may have important implications for studies of cardiogenesis.

A hormone-encoding gene identifies a pathway for cardiac but not skeletal muscle gene transcription

1994 ◽  
Vol 14 (5) ◽  
pp. 3115-3129
Author(s):  
C Grépin ◽  
L Dagnino ◽  
L Robitaille ◽  
L Haberstroh ◽  
T Antakly ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Regulatory Elements ◽  
Cardiac Cells ◽  
Skeletal Myocytes ◽  
Encoding Gene ◽  
Muscle Gene ◽  
Encoding Genes ◽  
Dependent Pathway ◽  
Gata Gene

In contrast to skeletal muscle, the mechanisms responsible for activation and maintenance of tissue-specific transcription in cardiac muscle remain poorly understood. A family of hormone-encoding genes is expressed in a highly specific manner in cardiac but not skeletal myocytes. This includes the A- and B-type natriuretic peptide (ANP and BNP) genes, which encode peptide hormones with crucial roles in the regulation of blood volume and pressure. Since these genes are markers of cardiac cells, we have used them to probe the mechanisms for cardiac muscle-specific transcription. Cloning and functional analysis of the rat BNP upstream sequences revealed unexpected structural resemblance to erythroid but not to muscle-specific promoters and enhancers, including a requirement for regulatory elements containing GATA motifs. A cDNA clone corresponding to a member of the GATA family of transcription factors was isolated from a cardiomyocyte cDNA library. Transcription of this GATA gene is restricted mostly to the heart and is undetectable in skeletal muscle. Within the heart, GATA transcripts are localized in ANP- and BNP-expressing myocytes, and forced expression of the GATA protein in heterologous cells markedly activates transcription from the natural cardiac muscle-specific ANP and BNP promoters. This GATA-dependent pathway defines the first mechanism for cardiac muscle-specific transcription. Moreover, the present findings reveal striking similarities between the mechanisms controlling gene expression in hematopoietic and cardiac cells and may have important implications for studies of cardiogenesis.

scholarly journals Multiple regulatory elements contribute differentially to muscle creatine kinase enhancer activity in skeletal and cardiac muscle.

1993 ◽  
Vol 13 (5) ◽  
pp. 2753-2764 ◽  
Author(s):  
S L Amacher ◽  
J N Buskin ◽  
S D Hauschka
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Regulatory Elements ◽  
High Level Expression ◽  
Muscle Creatine Kinase ◽  
Skeletal Myocytes ◽  
E Box ◽  
Nonmuscle Cells ◽  
High Level

We have used transient transfections in MM14 skeletal muscle cells, newborn rat primary ventricular myocardiocytes, and nonmuscle cells to characterize regulatory elements of the mouse muscle creatine kinase (MCK) gene. Deletion analysis of MCK 5'-flanking sequence reveals a striated muscle-specific, positive regulatory region between -1256 and -1020. A 206-bp fragment from this region acts as a skeletal muscle enhancer and confers orientation-dependent activity in myocardiocytes. A 110-bp enhancer subfragment confers high-level expression in skeletal myocytes but is inactive in myocardiocytes, indicating that skeletal and cardiac muscle MCK regulatory sites are distinguishable. To further delineate muscle regulatory sequences, we tested six sites within the MCK enhancer for their functional importance. Mutations at five sites decrease expression in skeletal muscle, cardiac muscle, and nonmuscle cells. Mutations at two of these sites, Left E box and MEF2, cause similar decreases in all three cell types. Mutations at three sites have larger effects in muscle than nonmuscle cells; an A/T-rich site mutation has a pronounced effect in both striated muscle types, mutations at the MEF1 (Right E-box) site are relatively specific to expression in skeletal muscle, and mutations at the CArG site are relatively specific to expression in cardiac muscle. Changes at the AP2 site tend to increase expression in muscle cells but decrease it in nonmuscle cells. In contrast to reports involving cotransfection of 10T1/2 cells with plasmids expressing the myogenic determination factor MyoD, we show that the skeletal myocyte activity of multimerized MEF1 sites is 30-fold lower than that of the 206-bp enhancer. Thus, MyoD binding sites alone are not sufficient for high-level expression in skeletal myocytes containing endogenous levels of MyoD and other myogenic determination factors.

Multiple regulatory elements contribute differentially to muscle creatine kinase enhancer activity in skeletal and cardiac muscle

1993 ◽  
Vol 13 (5) ◽  
pp. 2753-2764 ◽  
Author(s):  
S L Amacher ◽  
J N Buskin ◽  
S D Hauschka
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Regulatory Elements ◽  
High Level Expression ◽  
Muscle Creatine Kinase ◽  
Skeletal Myocytes ◽  
E Box ◽  
Nonmuscle Cells ◽  
High Level

We have used transient transfections in MM14 skeletal muscle cells, newborn rat primary ventricular myocardiocytes, and nonmuscle cells to characterize regulatory elements of the mouse muscle creatine kinase (MCK) gene. Deletion analysis of MCK 5'-flanking sequence reveals a striated muscle-specific, positive regulatory region between -1256 and -1020. A 206-bp fragment from this region acts as a skeletal muscle enhancer and confers orientation-dependent activity in myocardiocytes. A 110-bp enhancer subfragment confers high-level expression in skeletal myocytes but is inactive in myocardiocytes, indicating that skeletal and cardiac muscle MCK regulatory sites are distinguishable. To further delineate muscle regulatory sequences, we tested six sites within the MCK enhancer for their functional importance. Mutations at five sites decrease expression in skeletal muscle, cardiac muscle, and nonmuscle cells. Mutations at two of these sites, Left E box and MEF2, cause similar decreases in all three cell types. Mutations at three sites have larger effects in muscle than nonmuscle cells; an A/T-rich site mutation has a pronounced effect in both striated muscle types, mutations at the MEF1 (Right E-box) site are relatively specific to expression in skeletal muscle, and mutations at the CArG site are relatively specific to expression in cardiac muscle. Changes at the AP2 site tend to increase expression in muscle cells but decrease it in nonmuscle cells. In contrast to reports involving cotransfection of 10T1/2 cells with plasmids expressing the myogenic determination factor MyoD, we show that the skeletal myocyte activity of multimerized MEF1 sites is 30-fold lower than that of the 206-bp enhancer. Thus, MyoD binding sites alone are not sufficient for high-level expression in skeletal myocytes containing endogenous levels of MyoD and other myogenic determination factors.

scholarly journals Distinct gene expression patterns in skeletal and cardiac muscle are dependent on common regulatory sequences in the MLC1/3 locus.

1996 ◽  
Vol 16 (8) ◽  
pp. 4524-4534 ◽  
Author(s):  
M J McGrew ◽  
N Bogdanova ◽  
K Hasegawa ◽  
S H Hughes ◽  
R N Kitsis ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Consensus Sequence ◽  
Expression Patterns ◽  
Methylation Status ◽  
Regulatory Elements ◽  
Protein Isoforms ◽  
Regulatory Sequences ◽  
Enhancer Element

The myosin light-chain 1/3 locus (MLC1/3) is regulated by two promoters and a downstream enhancer element which produce two protein isoforms in fast skeletal muscle at distinct stages of mouse embryogenesis. We have analyzed the expression of transcripts from the internal MLC3 promoter and determined that it is also expressed in the atria of the heart. Expression from the MLC3 promoter in these striated muscle lineages is differentially regulated during development. In transgenic mice, the MLC3 promoter is responsible for cardiac-specific reporter gene expression while the downstream enhancer augments expression in skeletal muscle. Examination of the methylation status of endogenous and transgenic promoter and enhancer elements indicates that the internal promoter is not regulated in a manner similar to that of the MLC1 promoter or the downstream enhancer. A GATA protein consensus sequence in the proximal MLC3 promoter but not the MLC1 promoter binds with high affinity to GATA-4, a cardiac muscle- and gut-specific transcription factor. Mutation of either the MEF2 or GATA motifs in the MLC3 promoter attenuates its activity in both heart and skeletal muscles, demonstrating that MLC3 expression in these two diverse muscle types is dependent on common regulatory elements.

scholarly journals Analysis of muscle creatine kinase gene regulatory elements in skeletal and cardiac muscles of transgenic mice.

1996 ◽  
Vol 16 (4) ◽  
pp. 1649-1658 ◽  
Author(s):  
D B Donoviel ◽  
M A Shield ◽  
J N Buskin ◽  
H S Haugen ◽  
C H Clegg ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Transgenic Mice ◽  
Cardiac Muscle ◽  
Muscle Cells ◽  
Regulatory Elements ◽  
Muscle Creatine Kinase ◽  
Regulatory Regions ◽  
Mouse Muscle ◽  
Muscle Creatine

Regulatory regions of the mouse muscle creatine kinase (MCK) gene, previously discovered by analysis in cultured muscle cells, were analyzed in transgenic mice. The 206-bp MCK enhancer at nt-1256 was required for high-level expression of MCK-chloramphenicol acetyltransferase fusion genes in skeletal and cardiac muscle; however, unlike its behavior in cell culture, inclusion of the 1-kb region of DNA between the enhancer and the basal promoter produced a 100-fold increase in skeletal muscle activity. Analysis of enhancer control elements also indicated major differences between their properties in transgenic muscles and in cultured muscle cells. Transgenes in which the enhancer right E box or CArG element were mutated exhibited expression levels that were indistinguishable from the wild-type transgene. Mutation of three conserved E boxes in the MCK 1,256-bp 5' region also had no effect on transgene expression in thigh skeletal muscle expression. All these mutations significantly reduced activity in cultured skeletal myocytes. However, the enhancer AT-rich element at nt - 1195 was critical for expression in transgenic skeletal muscle. Mutation of this site reduced skeletal muscle expression to the same level as transgenes lacking the 206-bp enhancer, although mutation of the AT-rich site did not affect cardiac muscle expression. These results demonstrate clear differences between the activity of MCK regulatory regions in cultured muscles cells and in whole adult transgenic muscle. This suggests that there are alternative mechanism of regulating the MCK gene in skeletal and cardiac muscle under different physiological states.

scholarly journals THE ULTRASTRUCTURE OF MAMMALIAN CARDIAC MUSCLE

1961 ◽  
Vol 9 (2) ◽  
pp. 325-351 ◽  
Author(s):  
Richard J. Stenger ◽  
David Spiro
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Surface Membrane ◽  
Cardiac Cells ◽  
Papillary Muscles ◽  
Structural Components ◽  
Thin Filaments ◽  
Cytoplasmic Granules ◽  
Intercalated Discs ◽  
Structural Aspects

Papillary muscles of rat and dog hearts were fixed in such a way as to prevent excessive shortening during the procedure. The material was embedded in either araldite or methacrylate and was stained in various ways. The filamentous fine structure of mammalian cardiac muscle is similar to that previously described for striated skeletal muscle. The sarcomeres are composed of a set of thick and thin filaments which interdigitate in the A band proper. The filament ratios and the filamentous array are in accord with those found in skeletal muscle. The functional significance of this twofold array of filaments is not entirely clear. Various other structural aspects of cardiac cells such as surface membranes, mitochondria, nuclei, and cytoplasmic granules are described. The sarcoplasmic reticulum is discussed in detail as are the various structural components forming the intercalated discs. Fairly frequent deep invaginations of the sarcolemma with basement membrane are observed in addition to the intercalated discs. These surface membrane invaginations probably explain the branching appearance of cardiac fibers as seen under the light microscope.

scholarly journals Developmental stage-specific regulation of atrial natriuretic factor gene transcription in cardiac cells.

1994 ◽  
Vol 14 (1) ◽  
pp. 777-790 ◽  
Author(s):  
S Argentin ◽  
A Ardati ◽  
S Tremblay ◽  
I Lihrmann ◽  
L Robitaille ◽  
...  
Keyword(s):  
Cardiac Muscle ◽  
Cardiac Myocytes ◽  
Atrial Natriuretic Factor ◽  
Promoter Activity ◽  
Regulatory Elements ◽  
Cardiac Cells ◽  
Genetic Switch ◽  
Regulatory Pathways ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

Cardiac myocytes undergo a major genetic switch within the first week of postnatal development, when cell division ceases terminally and many cardiac genes are either activated or silenced. We have developed stage-specific cardiocyte cultures to analyze transcriptional control of the rat atrial natriuretic factor (ANF) gene to identify the mechanisms underlying tissue-specific and developmental regulation of this gene in the heart. The first 700 bp of ANF flanking sequences was sufficient for cardiac muscle- and stage-specific expression in both atrial and ventricular myocytes, and a cardiac muscle-specific enhancer was localized between -136 and -700 bp. Deletion of this enhancer markedly reduced promoter activity in cardiac myocytes and derepressed ANF promoter activity in nonexpressing cells. Two distinct domains of the enhancer appeared to contribute differentially to cardiac specificity depending on the differentiation stage of the myocytes. DNase I footprinting of the enhancer domain active in differentiated cells revealed four putative regulatory elements including an A+T-rich region and a CArG element. Deletion mutagenesis and promoter reconstitution assays revealed an important role for the CArG-containing element exclusively in cardiac cells, where its activity was switched on in differentiated myocytes. Transcriptional activity of the ANF-CArG box correlated with the presence of a cardiac- and stage-specific DNA-binding complex which was not recognized by the c-fos serum response element. Thus, the use of this in vitro model system representing stage-specific cardiac development unraveled the presence of different regulatory mechanisms for transcription of the ANF gene during cardiac differentiation and may be useful for studying the regulatory pathways of other genes that undergo switching during cardiac myogenesis.

scholarly journals Developmental stage-specific regulation of atrial natriuretic factor gene transcription in cardiac cells

1994 ◽  
Vol 14 (1) ◽  
pp. 777-790
Author(s):  
S Argentin ◽  
A Ardati ◽  
S Tremblay ◽  
I Lihrmann ◽  
L Robitaille ◽  
...  
Keyword(s):  
Cardiac Muscle ◽  
Cardiac Myocytes ◽  
Atrial Natriuretic Factor ◽  
Promoter Activity ◽  
Regulatory Elements ◽  
Cardiac Cells ◽  
Genetic Switch ◽  
Regulatory Pathways ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

Cardiac myocytes undergo a major genetic switch within the first week of postnatal development, when cell division ceases terminally and many cardiac genes are either activated or silenced. We have developed stage-specific cardiocyte cultures to analyze transcriptional control of the rat atrial natriuretic factor (ANF) gene to identify the mechanisms underlying tissue-specific and developmental regulation of this gene in the heart. The first 700 bp of ANF flanking sequences was sufficient for cardiac muscle- and stage-specific expression in both atrial and ventricular myocytes, and a cardiac muscle-specific enhancer was localized between -136 and -700 bp. Deletion of this enhancer markedly reduced promoter activity in cardiac myocytes and derepressed ANF promoter activity in nonexpressing cells. Two distinct domains of the enhancer appeared to contribute differentially to cardiac specificity depending on the differentiation stage of the myocytes. DNase I footprinting of the enhancer domain active in differentiated cells revealed four putative regulatory elements including an A+T-rich region and a CArG element. Deletion mutagenesis and promoter reconstitution assays revealed an important role for the CArG-containing element exclusively in cardiac cells, where its activity was switched on in differentiated myocytes. Transcriptional activity of the ANF-CArG box correlated with the presence of a cardiac- and stage-specific DNA-binding complex which was not recognized by the c-fos serum response element. Thus, the use of this in vitro model system representing stage-specific cardiac development unraveled the presence of different regulatory mechanisms for transcription of the ANF gene during cardiac differentiation and may be useful for studying the regulatory pathways of other genes that undergo switching during cardiac myogenesis.

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