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Wyszukujesz frazę "Awasthi, Sanjay" wg kryterium: Autor


Wyświetlanie 1-5 z 5
Tytuł:
Transport of glutathione-conjugates in human erythrocytes.
Autorzy:
Sharma, Rajendra
Awasthi, Sanjay
Zimniak, Piotr
Awasthi, Yogesh
Powiązania:
https://bibliotekanauki.pl/articles/1044319.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
glutathione-conjugates
active transporters
erythrocytes
multidrug resistance
Opis:
The last step of detoxification of both endogenous and environmental toxicants is typically a conjugation that produces a bulky hydrophilic molecule. The excretion of such conjugates out of cells is of sufficient biological importance to have led to the evolution of ATP-driven export pumps for this purpose. The substrate specificity of such transporters is broad, and in some cases it has been shown to include not only anionic conjugates but also neutral or weakly cationic drugs. In the present article, we review the molecular identity, functional and structural characteristics of these pumps, mainly on the example of human erythrocytes, and discuss their physiological role in detoxification and in the multidrug resistance phenotype of cancer cells.
Źródło:
Acta Biochimica Polonica; 2000, 47, 3; 751-762
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lipid peroxidation and cell cycle signaling : 4-hydroxynonenal, a key molecule in stress mediated signaling.
Autorzy:
Yang, Yusong
Sharma, Rajendra
Sharma, Abha
Awasthi, Sanjay
Awasthi, Yogesh
Powiązania:
https://bibliotekanauki.pl/articles/1043608.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
glutathione S-transferase
RLIP76
4-hydroxynonenal
RalBP1
cell cycle signaling
apoptosis
Opis:
Role of lipid peroxidation products, particularly 4-hydroxynonenal (4-HNE) in cell cycle signaling is becoming increasingly clear. In this article, recent studies suggesting an important role of 4-HNE in stress mediated signaling for apoptosis are critically evaluated. Evidence demonstrating the modulation of UV, oxidative stress, and chemical stress mediated apoptosis by blocking lipid peroxidation by the α-class glutathione S-transferases (GSTs) is presented which suggest an important role of these enzymes in protection against oxidative stress and a role of lipid peroxidation products in stress mediated signaling. Overexpression of 4-HNE metabolizing GSTs (mGSTA4-4, hGSTA4-4, or hGST5.8) protects cells against 4-HNE, oxidative stress (H2O2 or xanthine/xanthine oxidase), and UV-A mediated apoptosis by blocking JNK and caspase activation suggesting a role of 4-HNE in the mechanisms of apoptosis caused by these stress factors. The intracellular concentration of 4-HNE appears to be crucial for the nature of cell cycle signaling and may be a determinant for the signaling for differentiation, proliferation, transformation, or apoptosis. The intracellular concentrations of 4-HNE are regulated through a coordinated action of GSTs (GSTA4-4 and hGST5.8) which conjugate 4-HNE to GSH to form the conjugate (GS-HNE) and the transporter 76 kDa Ral-binding GTPase activating protein (RLIP76), which catalyze ATP-dependent transport of GS-HNE. A mild stress caused by heat, UV-A, or H2O2 with no apparent effect on the cells in culture causes a rapid, transient induction of hGST5.8 and RLIP76. These stress preconditioned cells acquire ability to metabolize and exclude 4-HNE at an accelerated pace and acquire relative resistance to apoptosis by UV and oxidative stress as compared to unconditioned control cells. This resistance of stress preconditioned cells can be abrogated by coating the cells with anti-RLIP76 antibodies which block the transport of GS-HNE. These studies and previous reports discussed in this article strongly suggest a key role of 4-HNE in stress mediated signaling.
Źródło:
Acta Biochimica Polonica; 2003, 50, 2; 319-336
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Functional reconstitution of Ral-binding GTPase activating protein, RLIP76, in proteoliposomes catalyzing ATP-dependent transport of glutathione conjugate of 4-hydroxynonenal.
Autorzy:
Sharma, Rajendra
Sharma, Abha
Yang, Yusong
Awasthi, Sanjay
Singhal, Sharad
Zimniak, Piotr
Awasthi, Yogesh
Powiązania:
https://bibliotekanauki.pl/articles/1043735.pdf
Data publikacji:
2002
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
RLIP76
4-hydroxynonenal
Ral-binding GTPase activating protein
transport
glutathione conjugate of 4-hydroxynonenal
Opis:
Earlier studies from our laboratories have shown that RLIP76, a previously described Ral-binding GTPase activating protein (Jullien-Flores et al., 1995, J. Biol. Chem. 270: 22473), is identical with the xenobiotic transporter DNP-SG ATPase, and can catalyze ATP-dependent transport of glutathione-conjugates as well as doxorubin (Awasthi et al., 2000, Biochemistry, 39: 9327). We have now reconstituted purified bacterially expressed RLIP76 in proteoliposomes, and have studied ATP-dependent uptake of the glutathione conjugate of 4-hydroxynonenal (GS-HNE) by these vesicles. Results of these studies show that RLIP76 reconstituted in proteoliposomes catalyzes ATP-dependent transport of GS-HNE against a concentration gradient. The transport of GS-HNE is saturable with respect to ATP as well as GS-HNE with Km values of 1.4 mM and 2.5 μM, respectively. These studies demonstrate that RLIP76 mediates active transport of GS-HNE, and are consistent with our previous work showing that RLIP76-mediated efflux of GS-HNE regulates the intracellular concentration of 4-HNE and thereby affects 4-HNE mediated signaling.
Źródło:
Acta Biochimica Polonica; 2002, 49, 3; 693-701
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Purification and functional reconstitution of intact ral-binding GTPase activating protein, RLIP76, in artificial liposomes.
Autorzy:
Singhal, Sharad
Singhal, Jyotsana
Cheng, JiZhong
Pikuła, Sławomir
Sharma, Rajendra
Zimniak, Piotr
Awasthi, Yogesh
Awasthi, Sanjay
Powiązania:
https://bibliotekanauki.pl/articles/1044153.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
RLIP76
glutathione-conjugate
anthracycline
transport
proteolysis
Opis:
We have recently shown that RLIP76, a ral-binding GTPase activating protein, mediates ATP-dependent transport of glutathione-conjugates (GS-E) and doxorubicin (DOX) (S. Awasthi et al., Biochemistry 39, 9327, 2000). Transport function of RLIP76 was found to be intact despite considerable proteolytic fragmentation in preparations used for those studies, suggesting either that the residual intact RLIP76 was responsible for transport activity, or that the transport activity could be reconstituted by fragments of RLIP76. If the former were true, intact RLIP76 would have a much higher specific activity for ATP-hydrolysis than the fragmented protein. We have addressed this question by comparing transport properties of recombinant RLIP76 and human erythrocyte membrane RLIP76 purified in buffers treated with either 100 or 500 μM serine protease inhibitor, PMSF. The purity and identity of recombinant and human erythrocyte RLIP76 was established by SDS/PAGE and Western-blot analysis. These studies confirmed the origin of the 38 kDa protein, previously referred to as DNP-SG ATPase, from RLIP76. Higher PMSF concentration resulted in lower yield of the 38 kDa band and higher yield of intact RLIP76 from both human and recombinant source. In contrast, the substrate-stimulated ATPase activity in presence of DNP-SG, doxorubicin, daunorubicin, or colchicine were unaffected by increased PMSF; similarly, ATP-dependent transport of doxorubicin in proteoliposomes reconstituted with RLIP76 was unaffected by higher PMSF. These results indicated that limited proteolysis by serine proteases does not abrogate the transport function of RLIP76. Comparison of transport kinetics for daunorubicin between recombinant vs human erythrocyte RLIP76 revealed higher specific activity of transport for tissue purified RLIP76, indicating that additional factors present in tissue purified RLIP76 can modulate its transport activity.
Źródło:
Acta Biochimica Polonica; 2001, 48, 2; 551-562
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport functions and physiological significance of 76 kDa Ral-binding GTPase activating protein (RLIP76).
Autorzy:
Awasthi, Sanjay
Sharma, Rajendra
Yang, Yusong
Singhal, Sharad
Pikula, Slawomir
Bandorowicz-Pikula, Joanna
Singh, Shivendra
Zimniak, Piotr
Awasthi, Yogesh
Powiązania:
https://bibliotekanauki.pl/articles/1043688.pdf
Data publikacji:
2002
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
RLIP76
RalBP1
glutathione conjugate
multidrug resistance
transport
Opis:
We have recently demonstrated that a previously known Ral-binding GTPase activating protein, RLIP76, can also catalyze ATP-dependent transport of various structurally unrelated xeno- and endobiotics irrespective of their net charge (Awasthi et al., 2000, Biochemistry, 39: 9327). RLIP76 is a non-ATP binding cassette (ABC) protein but it has two ATP-binding sites and shows basal ATPase activity which is stimulated in the presence of its transport substrates (allocrites) such as doxorubicin (DOX) and S-(2,4-dinitrophenyl) glutathione (DNP-SG). Proteoliposomes reconstituted with purified RLIP76 catalyze ATP-dependent, saturable transport of DOX, as well as of glutathione-conjugates including leukotrienes (LTC4) and the GSH-conjugate of 4-hydroxynonenal (GS-HNE). In erythrocytes the majority of transport activity for DOX, GS-HNE, and LTC4 is accounted for by RLIP76. Cells exposed to mild oxidative stress show a rapid and transient induction of RLIP76 resulting in an increased efflux of GS-HNE and acquire resistance to oxidative stress mediated toxicity and apoptosis. Cells transfected with RLIP76 acquire resistance to DOX through increased efflux of the drug suggesting its possible role in the mechanisms of drug-resistance. In this article, we discuss the significance of transport functions of RLIP76 highlighting its role in the defense mechanisms against oxidative injury, and modulation of signaling mechanisms.
Źródło:
Acta Biochimica Polonica; 2002, 49, 4; 855-867
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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