scholarly journals Poly(adenosine diphosphate ribose) polymerase activity and nicotinamide adenine dinucleotide in differentiating cardiac muscle

1976 ◽  
Vol 154 (2) ◽  
pp. 387-393 ◽  
Author(s):  
W C. Claycomb
Keyword(s):  
Cyclic Amp ◽  
Dna Synthesis ◽  
Cardiac Muscle ◽  
Dna Polymerase ◽  
Specific Activity ◽  
Polymerase Activity ◽  
Neonatal Rat ◽  
Dibutyryl Cyclic Amp ◽  
Fresh Tissue ◽  
Dna Polymerase Α

Poly(ADP-ribose) polymerase activity in nuclei isolated from differentiating cardiac muscle of the rat has been characterized and its activity measured during development. Optimum enzyme activity is observed at pH 8.5. Poly(ADP-ribose) polymerase is inhibited by ATP, thymidine, nicotinamide, theophylline, 3-isobutyl-1-methylxanthine and caffeine and stimulated by actinomycin D. The activity measured under optimal assay conditions increases during differentiation of cardiac muscle and is inversely related to the rate of DNA synthesis and to the activities of DNA polymerase α and thymidine kinase. When DNA synthesis and the activity of DNA polymerase α are inhibited in cardiac muscle of the 1-day-old neonatal rat by dibutyryl cyclic AMP or isoproterenol, the specific activity of poly(ADP-ribose) polymerase measured in isolated nuclei is increased. The concentration of NAD+ in cardiac muscle increases during postnatal development. In the adult compared with the 1-day-old neonatal rat the concentration of NAD+ relative to fresh tissue weight, DNA or protein increased 1.7-fold, 5.2-fold or 1.4-fold respectively. The concentration of NAD+ in cardiac muscle of the 1-day-old neonatal rat can be increased by approx. 20% by dibutyryl cyclic AMP. These data suggest that NAD+ and poly(ADP-ribose) polymerase may be involved with the repression of DNA synthesis and cell proliferation in differentiating cardiac muscle.

Increase in DNA polymerase α activity associated with DNA synthesis due to FSH or oestrogen in ovaries of immature rats

1986 ◽  
Vol 110 (2) ◽  
pp. 353-360 ◽  
Author(s):  
S. Usuki ◽  
M. Shioda
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerase ◽  
Dna Content ◽  
Specific Activity ◽  
Polymerase Activity ◽  
Dna Polymerase Α ◽  
Immature Rats ◽  
Hypophysectomized Rats ◽  
Α Activity ◽  
Intact Rats

ABSTRACT DNA polymerase activities and DNA content of ovaries from immature intact rats (4–29 days after birth), hypophysectomized rats and hormone-treated hypophysectomized rats were measured. During normal ovarian growth DNA polymerase α activity and DNA content of ovaries increased. The polymerase activity decreased gradually after hypophysectomy without any alteration in the DNA content. Administration of ovine FSH (2 μg/day) or oestradiol-17β (1 mg/day) to hypophysectomized rats enhanced ovarian DNA content and DNA polymerase α activity, whereas DNA polymerase β activity did not change significantly. These results suggest that DNA polymerase α participates in DNA synthesis in these ovaries. The specific activity of DNA polymerase α (the activity per μg DNA) in the ovaries increased between 4 and 14 days after birth, and then remained almost constant; the specific activity declined gradually after hypophysectomy. Administration of FSH or oestradiol-17β but not of ovine LH, progesterone or testosterone to hypophysectomized rats restored the specific activity. Mixing experiments with different kinds of ovarian extracts suggested that no activators of DNA polymerase α were present in the extracts. These results suggest that FSH or oestrogen causes the induction of DNA polymerase α accompanied by DNA synthesis during cell proliferation in ovaries of immature rats. J. Endocr. (1986) 110, 353–360

scholarly journals Biochemical aspects of cardiac muscle differentiation. Determination of deoxyribonucleic acid template availability and 3′-hydroxyl termini in nuclei and chromatin by using exogenous deoxyribonucleic acid polymerases

1978 ◽  
Vol 171 (2) ◽  
pp. 289-298 ◽  
Author(s):  
William C. Claycomb
Keyword(s):  
Dna Synthesis ◽  
Cardiac Muscle ◽  
Dna Polymerase ◽  
Deoxyribonucleic Acid ◽  
Dna Polymerases ◽  
Dna Polymerase Α ◽  
Dna Template ◽  
Hydroxyl Termini ◽  
Density Shift

Experiments were designed to determine whether DNA synthesis ceases in terminally differentiating cardiac muscle of the rat because the activity of the putative replicative DNA polymerase (DNA polymerase α) is lost or whether the activity of this enzyme is lost because DNA synthesis ceases. DNA-template availability and 3′-hydroxyl termini in nuclei and chromatin, isolated from cardiac muscle at various times during the developmental period in which DNA synthesis and the activity of DNA polymerase α are decreasing, were measured by using Escherichia coli DNA polymerase I, Micrococcus luteus DNA polymerase and DNA polymerase α under optimal conditions. Density-shift experiments with bromodeoxyuridine triphosphate and isopycnic analysis indicate that DNA chains being replicated semi-conservatively in vivo continue to be elongated in isolated nuclei by exogenous DNA polymerases. DNA template and 3′-hydroxyl termini available to exogenously added DNA polymerases do not change as cardiac muscle differentiates and the rate of DNA synthesis decreases and ceases in vivo. Template availability and 3′-hydroxyl termini are also not changed in nuclei isolated from cardiac muscle in which DNA synthesis had been inhibited by administration of isoproterenol and theophylline to newborn rats. DNA-template availability and 3′-hydroxyl termini, however, were substantially increased in nuclei and chromatin from cardiac muscle of adult rats. This increase is not due to elevated deoxyribonuclease activity in nuclei and chromatin of the adult. Electron microscopy indicates that this increase is also not due to dispersal of the chromatin or disruption of nuclear morphology. Density-shift experiments and isopycnic analysis of DNA from cardiac muscle of the adult show that it is more fragmented than DNA from cardiac-muscle cells that are, or have recently ceased, dividing. These studies indicate that DNA synthesis ceases in terminally differentiating cardiac muscle because the activity of a replicative DNA polymerase is lost, rather than the activity of this enzyme being lost because DNA synthesis ceases.

scholarly journals Heterotrimeric PCNA Increases the Activity and Fidelity of Dbh, a Y-family Translesion DNA Polymerase Prone to Creating Single-Base Deletion Mutations

2020 ◽  
Author(s):  
Yifeng Wu ◽  
William Jaremko ◽  
Ryan C. Wilson ◽  
Janice D. Pata
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerase ◽  
Polymerase Activity ◽  
List Type ◽  
Single Base ◽  
Deletion Mutations ◽  
Single Base Deletion ◽  
Translesion Dna ◽  
Y Family

AbstractDbh is a Y-family translesion DNA polymerase from Sulfolobus acidocaldarius, an archaeal species that grows in harsh environmental conditions. Biochemically, Dbh displays a distinctive mutational profile, creating single-base deletion mutations at extraordinarily high frequencies (up to 50%) in specific repeat sequences. In cells, however, Dbh does not appear to contribute significantly to spontaneous frameshifts in these same sequence contexts. This suggests that either the error-prone DNA synthesis activity of Dbh is reduced in vivo and/or Dbh is restricted from replicating these sequences. Here, we test the hypothesis that the propensity for Dbh to make single base deletion mutations is reduced through interaction with the S. acidocaldarius heterotrimeric sliding clamp processivity factor, PCNA-123. We first confirm that Dbh physically interacts with PCNA-123, with the interaction requiring both the PCNA-1 subunit and the C-terminal 10 amino acids of Dbh, which contain a predicted PCNA-interaction peptide (PIP) motif. This interaction stimulates the polymerase activity of Dbh, even on short, linear primer-template DNA by increasing the rate of nucleotide incorporation. This stimulation requires an intact PCNA-123 heterotrimer and a DNA duplex length of at least 18 basepairs, the minimal length predicted from structural data to bind to both the polymerase and the clamp. Finally, we find that PCNA-123 increases the fidelity of Dbh on a single-base deletion hotspot sequence 3-fold by promoting an increase in the rate of correct, but not incorrect, nucleotide addition and propose that PCNA-123 induces Dbh to adopt a more active conformation that is less prone to creating deletions during DNA synthesis.HighlightsPCNA increases the fidelity of Dbh polymerase on a deletion-hotspot sequence.The interaction stimulates incorporation of the correct, but not incorrect, nucleotide.A minimal duplex length of 18 bp is required for PCNA to stimulate polymerase activity.Structural modeling suggests that PCNA induces a conformational change in Dbh.

scholarly journals Factors that prevent the premature appearance of glucokinase in neonatal rat liver

1980 ◽  
Vol 186 (3) ◽  
pp. 817-826 ◽  
Author(s):  
M J O Wakelam ◽  
M B Allen ◽  
D G Walker
Keyword(s):  
Angiotensin Ii ◽  
Cyclic Amp ◽  
Insulin Release ◽  
Rat Liver ◽  
Neonatal Rat ◽  
Oral Glucose ◽  
Dibutyryl Cyclic Amp ◽  
Simultaneous Treatment ◽  
Physiological Factors ◽  
Glucose Administration

1. The physiological factors that prevent the precocious appearance of glucokinase activity in the 13-day-old rat that can be induced by oral glucose administration were explored. 2. Evidence is presented that the galactose component of milk sugar is inhibitory. In the absence of this inhibitory galactose, the amount of glucose necessary to effect appreciable induction is greater than that present in milk. 3. The induction is prevented both by administration of mannoheptulose, which inhibits insulin release, and by excess insulin; the amount of insulin available therefore seems to be critical. 4. The inhibition of induction by galactose does not appear to be via competition with glucose but by enhancing insulin release and thereby making this excessive. The relative amounts of glucose and insulin appear to be important in regulating glucokinase induction. 5. The precocious induction of glucokinase by glucose is inhibited by simultaneous treatment with approriate amounts of adrenaline, glucagon, dibutyryl cyclic AMP or isoprenaline but not by vasopressin or angiotensin II. 6. No single cause of glucokinase induction in neonatal rat liver can be recognized. The process is subject to regulation by many factors at a time subsequent to when competence to synthesize the enzyme has been established.

scholarly journals REPAIR DNA SYNTHESIS IN DIFFERENTIATED EMBRYONIC MUSCLE CELLS

1972 ◽  
Vol 52 (3) ◽  
pp. 589-597 ◽  
Author(s):  
Frank E. Stockdale ◽  
Michael C. O'neill
Keyword(s):  
Skeletal Muscle ◽  
Dna Synthesis ◽  
Dna Polymerase ◽  
Uv Irradiation ◽  
Life Time ◽  
Muscle Cells ◽  
Polymerase Activity ◽  
Repair Synthesis ◽  
Entire Life ◽  
Embryonic Muscle

The differentiation of embryonic skeletal muscle cells is closely coupled with the cessation of normal DNA replication. Once these cells begin to differentiate, they normally never undergo semiconservative replication of DNA during the entire life time of the muscle cell. Cessation of DNA synthesis has been shown to be accompanied by a loss of 80–90% of the replicative DNA polymerase activity of these cells. Despite this loss the studies reported here demonstrate that muscle cells retain the ability to synthesize DNA of a repair type after UV irradiation. These results suggest that the control exercised over semiconservative DNA synthesis during differentiation of these cells does not extend to repair synthesis after UV irradiation.

Stimulation of aromatase activity in the fetal rat testis by cyclic AMP and FSH

1988 ◽  
Vol 118 (3) ◽  
pp. 485-489 ◽  
Author(s):  
J.-P. Weniger ◽  
A. Zeis
Keyword(s):  
Cyclic Amp ◽  
Specific Activity ◽  
Isotopic Dilution ◽  
Aromatase Activity ◽  
Dibutyryl Cyclic Amp ◽  
Rat Testis ◽  
Fetal Rat ◽  
Fetal Rats ◽  
Stimulation Of

ABSTRACT The effect of dibutyryl cyclic AMP and FSH on oestrogen biosynthesis was investigated in testes from 18- to 21-day-old fetal rats cultured in vitro in the presence of tritiated testosterone. Oestrone and oestradiol concentrations were measured by determination of constant specific activity after isotopic dilution. Dibutyryl cyclic AMP and FSH markedly stimulated the conversion of testosterone into both oestrone and oestradiol at all stages studied. Oestradiol synthesis was stimulated by two- to sevenfold, while stimulation of oestrone synthesis was even greater. The results demonstrate that the aromatase enzyme system of the fetal rat testis responds to cyclic AMP and FSH. J. Endocr. (1988) 118, 485–489

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