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Isozymes delta of phosphoinositide-specific phospholipase C and their role in signal transduction in the cell.

100%
Ochocka A.-M., Pawelczyk T.
Acta Biochimica Polonica
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2003
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vol. 50
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issue 4
1097-1110
EN
Phospholipase C (PLC, EC 3.1.4.11) is an enzyme crucial for the phosphoinositol pathway and whose activity is involved in eukaryotic signal transduction as it generates two second messengers: diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). There are four major types of phospholipase C named: β, γ, δ and the recently discovered ε, but this review will focus only on the recent advances for the γ isozymes of PLC. So far, four d isozymes (named γ1-4) have been discovered and examined. They differ with regard to cellular distribution, activities, biochemical features and involvement in human ailments.
2
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Overexpression of ID1 reverses the repression of human dental pulp stem cells differentiation induced by TWIST1 silencing

81%
Maciejewska I., Sakowicz-Burkiewicz M., Krzeminska M., Pawelczyk T.
Acta Biochimica Polonica
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2017
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vol. 64
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issue 4
615-619
EN
Multiple studies showed that the cessation of TWIST1 expression is the prerequisite for osteoblasts' maturation. However, recent reports revealed that the function of TWIST1 is different in the dental pulp stem cells (DPSCs), where a high level of TWIST1 expression promoted DPSCs' differentiation. The aim of the study was to investigate the impact of TWIST1 and ID1 on the differentiation process in the human DPSCs. Methods: TWIST1 and ID1 expression in the DSPCs was modulated by lentivirus transduction. Genes expression was assessed with qRT-PCR. The proteins level was evaluated by Western blot. The DPSCs differentiation was assessed with the proliferation, alkaline phosphatase (ALP) activity, and calcium concentration assays. Results: TWIST1 silencing suppressed the expression of ID1 and both the early and late markers of odontoblasts' differentiation detected at the transcript and protein level. The forced overexpression of ID1 increased the expression of the late markers of odontoblasts differentiation but diminished the expression of the early markers. DPCSs with the silenced TWIST1 and subsequent ID1 overexpression displayed an increase in the expression of the late markers of odontoblasts differentiation. Cells with silenced TWIST1 and overexpressing ID1 had increased activity of ALP, higher calcium concentration and decreased proliferation rate. The high level of ID1 expression might be a critical factor stimulating DPSCs differentiation and it might compensate the repressed differentiation of DPSCs caused by TWIST1 silencing. Conclusion: The mutual correlation between the expression level of TWIST1 and ID1 might be a critical factor driving the process of the human odontoblasts' differentiation.
3
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Recent advances in studies on biochemical and structural properties of equilibrative and concentrative nucleoside transporters

81%
Podgorska M., Kocbuch K., Pawelczyk T.
Acta Biochimica Polonica
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2005
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vol. 52
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issue 4
749-758
EN
Nucleoside transporters (NT) facilitate the movement of nucleosides and nucleobases across cell membranes. NT-mediated transport is vital for the synthesis of nucleic acids in cells that lack de novo purine synthesis. Some nucleosides display biological activity and act as signalling molecules. For example, adenosine exerts a potent action on many physiological processes including vasodilatation, hormone and neurotransmitter release, platelet aggregation, and lipolysis. Therefore, carrier-mediated transport of this nucleoside plays an important role in modulating cell function, because the efficiency of the transport processes determines adenosine availability to its receptors or to metabolizing enzymes. Nucleoside transporters are also key elements in anticancer and antiviral therapy with the use of nucleoside analogues. Mammalian cells possess two major nucleoside transporter families: equilibrative (ENT) and concentrative (CNT) Na+-dependent ones. This review characterizes gene loci, substrate specificity, tissue distribution, membrane topology and structure of ENT and CNT proteins. Regulation of nucleoside transporters by various factors is also presented.
4
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Effect of insulin and glucose on adenosine metabolizing enzymes in human B lymphocytes

71%
Kocbuch K., Sakowicz-Burkiewicz M., Grden M., Szutowicz A., Pawelczyk T.
Acta Biochimica Polonica
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2009
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vol. 56
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issue 3
439-446
EN
In diabetes several aspects of immunity are altered, including the immunomodulatory action of adenosine. Our study was undertaken to investigate the effect of different glucose and insulin concentrations on activities of adenosine metabolizing enzymes in human B lymphocytes line SKW 6.4. The activity of adenosine deaminase in the cytosolic fraction was very low and was not affected by different glucose concentration, but in the membrane fraction of cells cultured with 25 mM glucose it was decreased by about 35% comparing to the activity in cells maintained in 5 mM glucose, irrespective of insulin concentration. The activities of 5'-nucleotidase (5'-NT) and ecto-5'-NT in SKW 6.4 cells depended on insulin concentration, but not on glucose. Cells cultured with 10-8 M insulin displayed an about 60% lower activity of cytosolic 5'-NT comparing to cells maintained at 10-11 M insulin. The activity of ecto-5'-NT was decreased by about 70% in cells cultured with 10-8 M insulin comparing to cells grown in 10-11 M insulin. Neither insulin nor glucose had an effect on adenosine kinase (AK) activity in SKW 6.4 cells or in human B cells isolated from peripheral blood. The extracellular level of adenosine and inosine during accelerated catabolism of cellular ATP depended on glucose, but not on insulin concentration. Concluding, our study demonstrates that glucose and insulin differentially affect the activities of adenosine metabolizing enzymes in human B lymphocytes, but changes in those activities do not correlate with the adenosine level in cell media during accelerated ATP catabolism, implying that nucleoside transport is the primary factor determining the extracellular level of adenosine.
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