Free ADP levels in transgenic mouse liver expressing creatine kinase. Effects of enzyme activity, phosphagen type, and substrate concentration.

Creatine kinase (CK) is normally found at high levels in muscle and brain and catalyzes the reaction phosphocreatine (PCr) + MgADP + H+<==>creatine (Cr) + MgATP. CK is not normally found at high levels in liver. A line of transgenic mice that express high levels of the BB-dimer of CK (CKB) in liver has allowed us to assess the role of CKB during periods of low oxygen stress. During 40 min of ischemia of normal perfused livers at 25 degrees C, ATP levels are depleted, and pH decreases to 6.6. pH recovers to a preischemic level after 30 min of reperfusion of normal livers; however, P(i) levels are significantly higher and ATP levels significantly lower than preischemic values. In transgenic liver with an initial PCr-to-ATP ratio of 4.5, ATP levels are maintained until PCr is markedly depleted. pH remains at preischemic levels for 16 min of ischemia of transgenic livers. During this length of ischemia in normal livers, pH has dropped to 6.9. pH, P(i), and ATP levels return to preischemic values within 30 min of reperfusion in transgenic livers containing PCr and CK. During 90 min of hypoxia of normal perfused livers at 37 degrees C, ATP is depleted. After 15 min of hypoxia of normal livers, there is a significant increase in the release of lactate dehydrogenase (LDH). In transgenic livers, ATP is maintained, and no increase in LDH release is observed for up to 90 min, depending on the level of PCr before hypoxia. These results demonstrate the role of CKB in buffering ATP levels and regulating intracellular pH during periods of low oxygen stress.(ABSTRACT TRUNCATED AT 250 WORDS)

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Energy metabolism and regeneration in transgenic mouse liver expressing creatine kinase after major hepatectomy

Gastroenterology ◽

10.1053/gast.1996.v110.pm8613006 ◽

1996 ◽

Vol 110 (4) ◽

pp. 1166-1174 ◽

Cited By ~ 29

Author(s):

S Satoh ◽

A Tanaka ◽

E Hatano ◽

T Inomoto ◽

S Iwata ◽

...

Keyword(s):

Creatine Kinase ◽

Energy Metabolism ◽

Transgenic Mouse ◽

Mouse Liver ◽

Major Hepatectomy

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In vivo1H MRS and31P MRSI of the response to cyclocreatine in transgenic mouse liver expressing creatine kinase

NMR in Biomedicine ◽

10.1002/nbm.3391 ◽

2015 ◽

Vol 28 (12) ◽

pp. 1634-1644 ◽

Cited By ~ 1

Author(s):

Min-Hui Cui ◽

Kamaiah Jayalakshmi ◽

Laibin Liu ◽

Chandan Guha ◽

Craig A. Branch

Keyword(s):

Creatine Kinase ◽

Transgenic Mouse ◽

Mouse Liver

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Inhibition of tumor necrosis factor-induced apoptosis in transgenic mouse liver expressing creatine kinase

Liver International ◽

10.1111/j.1478-3231.2004.0939.x ◽

2004 ◽

Vol 24 (4) ◽

pp. 384-393 ◽

Cited By ~ 25

Author(s):

Etsuro Hatano ◽

Akira Tanaka ◽

Akiyoshi Kanazawa ◽

Shigeru Tsuyuki ◽

Shoji Tsunekawa ◽

...

Keyword(s):

Creatine Kinase ◽

Tumor Necrosis Factor ◽

Transgenic Mouse ◽

Mouse Liver ◽

Tumor Necrosis ◽

Induced Apoptosis ◽

Necrosis Factor

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Creatine kinase of heart mitochondria. The progressive loss of enzyme activity during in vivo ischemia and its correlation to depressed myocardial function.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)89717-4 ◽

1985 ◽

Vol 260 (1) ◽

pp. 208-214 ◽

Cited By ~ 5

Author(s):

J A Bittl ◽

M L Weisfeldt ◽

W E Jacobus

Keyword(s):

Creatine Kinase ◽

Enzyme Activity ◽

Myocardial Function ◽

Heart Mitochondria ◽

Progressive Loss

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Altered Proteolysis and Global Gene Expression in Hepatitis B Virus X Transgenic Mouse Liver

Journal of Virology ◽

10.1128/jvi.80.3.1405-1413.2006 ◽

2006 ◽

Vol 80 (3) ◽

pp. 1405-1413 ◽

Cited By ~ 21

Author(s):

Zongyi Hu ◽

Zhensheng Zhang ◽

Jin Woo Kim ◽

Ying Huang ◽

T. Jake Liang

Keyword(s):

Gene Expression ◽

Hepatitis B Virus ◽

Hepatitis B ◽

Transgenic Mouse ◽

Mouse Liver ◽

Global Gene Expression ◽

Pleiotropic Effect ◽

B Virus ◽

Number Of Genes

ABSTRACT Hepatitis B virus X (HBX) is essential for the productive infection of hepatitis B virus (HBV) in vivo and has a pleiotropic effect on host cells. We have previously demonstrated that the proteasome complex is a cellular target of HBX, that HBX alters the proteolytic activity of proteasome in vitro, and that inhibition of proteasome leads to enhanced viral replication, suggesting that HBX and proteasome interaction plays a crucial role in the life cycle and pathogenesis of HBV. In the present study, we tested the effect of HBX on the proteasome activities in vivo in a transgenic mouse model in which HBX expression is developmentally regulated by the mouse major urinary promoter in the liver. In addition, microarray analysis was performed to examine the effect of HBX expression on the global gene expression profile of the liver. The results showed that the peptidase activities of the proteasome were reduced in the HBX transgenic mouse liver, whereas the activity of another cellular protease was elevated, suggesting a compensatory mechanism in protein degradation. In the microarray analysis, diverse genes were altered in the HBX mouse livers and the number of genes with significant changes increased progressively with age. Functional clustering showed that a number of genes involved in transcription and cell growth were significantly affected in the HBX mice, possibly accounting for the observed pleiotropic effect of HBX. In particular, insulin-like growth factor-binding protein 1 was down-regulated in the HBX mouse liver. The down-regulation was similarly observed during acute woodchuck hepatitis virus infection. Other changes including up-regulation of proteolysis-related genes may also contribute to the profound alterations of liver functions in HBV infection.

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β-GLUCURONIDASE OF RABBIT POLYMORPHONUCLEAR LEUCOCYTES

Canadian Journal of Research ◽

10.1139/cjr50e-012 ◽

1950 ◽

Vol 28e (3) ◽

pp. 69-79 ◽

Cited By ~ 10

Author(s):

R. J. Rossiter ◽

Esther Wong

Keyword(s):

Enzyme Activity ◽

Blood Plasma ◽

Substrate Concentration ◽

Final Concentration ◽

White Cell ◽

Polymorphonuclear Leucocytes ◽

Michaelis Constant ◽

Glucuronidase Activity ◽

Arsanilic Acid ◽

Optimum Ph

Rabbit polymorphonuclear leucocytes contain an enzyme capable of hydrolyzing biosynthetic phenolphthalein mono-β-glucuronide. The concentration of the enzyme in the white cell is some 2000 times the concentration of the enzyme in the blood plasma. Under the conditions of study, the β-glucuronidase activity was proportional to the concentration of the enzyme. The effect of substrate concentration on the enzyme activity was studied and the Michaelis constant, Ks, determined. The course of the reaction was linear with time for the first 12 hr. and then fell off slightly during the next 12 hr. The optimum pH of the enzyme was 4.45 in either 0.2 M acetate or 0.2 M phthalate buffer. It was not inhibited by cyanide, azide, iodoacetate, fluoride, glycine, thiourea, urethane, arsanilic acid, acetophenone, o-cresol or m-cresol, in a final concentration of 0.01 M. The possible function of β-glucuronidase in rabbit polymorphonuclear leucocytes is discussed.

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Immunoassay of muscle-specific creatine kinase with a monoclonal antibody and application to myogenesis and muscular dystrophy

Biochemical Journal ◽

10.1042/bj2130417 ◽

1983 ◽

Vol 213 (2) ◽

pp. 417-425 ◽

Cited By ~ 8

Author(s):

G E Morris ◽

L P Head

Keyword(s):

Monoclonal Antibody ◽

Creatine Kinase ◽

Enzyme Activity ◽

Total Protein ◽

Plasma Concentrations ◽

Thigh Muscle ◽

Cell Protein ◽

Enzyme Linked Immunosorbent Assay ◽

Activity Measurements

A competition e.l.i.s.a. (enzyme-linked immunosorbent assay) is described that enables direct measurement of the muscle-specific polypeptide of chick creatine kinase (M-CK) in extracts of differentiating muscle-cell cultures and in blood plasma samples, even in the presence of embryonic, or brain-type, creatine kinase. The characteristics of the assay can be considerably improved by the use of a monoclonal antibody, CK-ART, instead of rabbit antisera, and we offer an explanation for this in terms of heterogeneity of antibody affinities in polyclonal antisera. In addition to native enzyme, the assay will measure creatine kinase unfolded and inactivated by 8 M-urea treatment. During chick muscle differentiation in vitro, M-CK increased from 7.5% of the total creatine kinase at 24h to 76.0% at 143h, in good agreement with isoenzyme separation data. As a percentage of the total cell protein, M-CK increased by 156-340-fold over the same period and constituted 0.38-0.56% of the total protein in late cultures. E.l.i.s.a. measurements on 17-20-day embryonic thigh-muscle extracts, which contain almost exclusively M-CK, agree well with enzyme activity and radioimmunoassay. M-CK constituted 0.7-1.6% of the total protein in 17-19-day embryonic thigh muscle. Plasma M-CK concentrations in normal 2-8-week-old chickens were found to be in the range 0.5-0.9 micrograms/ml. Plasma concentrations of 32-56 micrograms/ml were found in 8-week-old dystrophic chickens by both e.l.i.s.a. and enzyme-activity measurements. The results suggest that inactive or unfolded forms of M-CK do not normally exist, in any significant amounts, in cell and tissue extracts or in freshly prepared samples of plasma.

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