Expression and regulation of the anti-apoptotic MCL-1 protein in human B-cell lymphoma
Expression and regulation of the anti-apoptotic MCL-1 protein in human B-cell lymphoma
Mcl-1 is an anti-apoptotic member of the Bcl-2 family of proteins. Enforced expression of Mcl-1 promotes lymphomagenesis in transgenic mice. However, the functional role and mechanisms controlling expression of Mcl-1 in human B-cell lymphoma remain unclear. Using immunoblotting and immunohistochemistry, I demonstrated that Mcl-1 was widely expressed in a panel of lymphoma cell lines and in primary material from patients with different types of NHL. Reporter gene analysis demonstrated that Mcl-1 promoter activity with B-cell lymphoma cells was dependent on the presence of binding sites for Ets, Spl and SRF transcription factors. A high level of Mcl-1 expression was required for B-lymphoma cell survival since transfection of Mcl-1 specific antisense oligodeoxynucleotides was sufficient to trigger apoptosis.
Cisplatin-induced apoptosis of B-lymphoma cells was associated with decreased expression of the Mcl-1 RNA and protein. Caspase-dependent cleavage of Mcl-1 in B-cell lines and primary malignant B-cells generated a 28kDa Mcl-1 cleavage fragment which accumulated during apoptosis and Mcl-1 was efficiently cleaved by caspases at evolutionarily conserved aspartic acid residues (Asp127 and Asp157) in vitro.
Overexpression of the carboxyl terminal Mcl-1 cleavage product containing the BH3 domain into NIH3T3 cells was sufficient to induce cell death. In contrast to Mcl-1, Bcl-2 and Bcl-XL were not substantially down regulated and were relatively resistant to caspase cleavage in vitro and in intact cells. Mcl-1 strongly interacted with the pro-apoptotic Bim, and this interaction is likely to influence the apoptotic threshold.
Mcl-1 is a key survival protein in human B cell lymphoma and Mcl-1 down regulation and cleavage is likely to serve as a positive feedback loop to ensure efficient cell killing. Interfering with Mcl-1 function may provide an attractive strategy in the treatment of Mcl-1 positive B-cell lymphoma.
University of Southampton
2004
Michels, Jörg Erwin
(2004)
Expression and regulation of the anti-apoptotic MCL-1 protein in human B-cell lymphoma.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Mcl-1 is an anti-apoptotic member of the Bcl-2 family of proteins. Enforced expression of Mcl-1 promotes lymphomagenesis in transgenic mice. However, the functional role and mechanisms controlling expression of Mcl-1 in human B-cell lymphoma remain unclear. Using immunoblotting and immunohistochemistry, I demonstrated that Mcl-1 was widely expressed in a panel of lymphoma cell lines and in primary material from patients with different types of NHL. Reporter gene analysis demonstrated that Mcl-1 promoter activity with B-cell lymphoma cells was dependent on the presence of binding sites for Ets, Spl and SRF transcription factors. A high level of Mcl-1 expression was required for B-lymphoma cell survival since transfection of Mcl-1 specific antisense oligodeoxynucleotides was sufficient to trigger apoptosis.
Cisplatin-induced apoptosis of B-lymphoma cells was associated with decreased expression of the Mcl-1 RNA and protein. Caspase-dependent cleavage of Mcl-1 in B-cell lines and primary malignant B-cells generated a 28kDa Mcl-1 cleavage fragment which accumulated during apoptosis and Mcl-1 was efficiently cleaved by caspases at evolutionarily conserved aspartic acid residues (Asp127 and Asp157) in vitro.
Overexpression of the carboxyl terminal Mcl-1 cleavage product containing the BH3 domain into NIH3T3 cells was sufficient to induce cell death. In contrast to Mcl-1, Bcl-2 and Bcl-XL were not substantially down regulated and were relatively resistant to caspase cleavage in vitro and in intact cells. Mcl-1 strongly interacted with the pro-apoptotic Bim, and this interaction is likely to influence the apoptotic threshold.
Mcl-1 is a key survival protein in human B cell lymphoma and Mcl-1 down regulation and cleavage is likely to serve as a positive feedback loop to ensure efficient cell killing. Interfering with Mcl-1 function may provide an attractive strategy in the treatment of Mcl-1 positive B-cell lymphoma.
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Published date: 2004
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Local EPrints ID: 465374
URI: http://eprints.soton.ac.uk/id/eprint/465374
PURE UUID: aa3d5db4-c5ae-431e-a1cc-bbace236debd
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Date deposited: 05 Jul 2022 00:40
Last modified: 05 Jul 2022 00:40
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Author:
Jörg Erwin Michels
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