Md Shahnawaz

Chosun University, Gwangju, Gwangju, South Korea

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Publications (5)17.31 Total impact

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    ABSTRACT: Apoptosis is essential in the death process induced by Amyloid-β (Aβ), a major constituent of diffuse plaques found in Alzheimer's disease patients. However, we have found that caspase activation and cell death induced by staurosporine, employed to induce the intrinsic mitochondria-dependent apoptotic pathway, were significantly reduced by 42 amino-acid Aβ42, implying that the peptide also has a negative effect on the apoptotic process. The inhibitory effect of Aβ42 on the apoptotic pathway is associated with its interaction with procaspase-9 and consequent inhibition of Apaf-1 apoptosome assembly. We detected the inhibitory effect in the early stage (< 8 h) of apoptosis, but later caspase activation becomes obvious. Thus we inferred that the inhibitory process on apoptosis begins at an early stage, and the later robust activation surpasses it. We propose that the apoptotic manifestation in Aβ-treated cells is a combined consequence of those anti- and pro-apoptotic processes
    Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 01/2014; · 4.81 Impact Factor
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    ABSTRACT: Apoptosis is essential in the death process induced by Amyloid-β (Aβ), a major constituent of diffuse plaques found in Alzheimer's disease patients. However, we have found that caspase activation and cell death induced by staurosporine, employed to induce the intrinsic mitochondria-dependent apoptotic pathway, was significantly reduced by 42 amino-acid Aβ42, implying that the peptide also has a negative effect on the apoptotic process. The inhibitory effect of Aβ42 on the apoptotic pathway is associated with its interaction with procaspase-9 and consequent inhibition of Apaf-1 apoptosome assembly. We detected the inhibitory effect in the early stage (<8h) of apoptosis, but later caspase activation becomes obvious. Thus we inferred that the inhibitory process on apoptosis begins at an early stage, and the later robust activation surpasses it. We propose that the apoptotic manifestation in Aβ-treated cells is a combined consequence of those anti- and pro-apoptotic processes.
    Biochimica et Biophysica Acta 01/2014; · 4.66 Impact Factor
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    ABSTRACT: The aggregation of β-amyloid (Aβ) peptide from its monomeric to its fibrillar form importantly contributes to the development of Alzheimer's disease. Here, we investigated the effects ofE. coli maltose binding protein (MBP), which has been previously used as a fusion protein, on Aβ42 fibrillization, in order to improve understanding of the self-assembly process and the cytotoxic mechanism of Aβ42. MBP, at a sub-stoichiometric ratio with respect to Aβ42, was found to have chaperone-like inhibitory effects on β-sheet fibril formation, due to the accumulation of Aβ42 aggregates by sequestration of active Aβ42 species as Aβ42-MBP complexes. Furthermore, MBP increased the lag time of Aβ42 polymerization, decreased the growth rate of fibril extension, and suppressed Aβ42 mediated toxicity in human neuroblastoma SH-SY5Y cells. It appears that MBP decreases the active concentration of Aβ42 by sequestering it as Aβ42-MBP complex, and that this sequestration suppresses ongoing nucleation and retards the growth rate of Aβ42 species required for fibril formation. We speculate that inhibition of the growth rate of potent Aβ42 species by MBP suppresses Aβ42-mediated toxicity in SH-SY5Y cells.
    Archives of Biochemistry and Biophysics 08/2013; · 3.37 Impact Factor
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    ABSTRACT: Addition of amyloid β (Aβ) peptide Aβ40 to Aβ42 can delay Aβ42 aggregation, but consequent cytotoxicity has been reported to be enhanced or diminished. In the present study, we found that cytotoxicity was enhanced when human neuroblastoma SH-SY5Y cells were incubated in a mixture of wt Aβ42 and Aβ40wt at a ratio of 1 : 10-20 (0.1 : 1-2 μM) for 24-36 h, whereas the enhancement was detected in cells incubated for longer times (48-60 h) with the less amyloidogenic Flemish Aβ40 variant or in cells incubated for as short as 12 h with the more amyloidogenic Dutch variant. Reductions in cytotoxicity by Aβ40 were most prominently observed in the Flemish and wt Aβ40/Aβ42 mixture at ratio 1 : 20 incubated for a short time (~12 h). The most cytotoxic Aβ40/Aβ42 mixtures were enriched in Aβ protofibril-like structures, implying a strong correlation between cytotoxicity and this structure, the formation of which was dependent on amyloidogenic properties and incubation time. The consequences of the interactions were probably because of the different amyloidogenic properties of the Aβ40 variants, rather than to those of Aβ42, because aggregation rates of Aβ40 variants were highly dependent on sequence, whereas those of Aβ42 variants were not. These studies highlight a potential role for Aβ40 in cytotoxicity and provide novel mechanistic insights into the pathogenesis of each familial Alzheimer's disease-associated Aβ40 variant. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.
    Journal of Peptide Science 07/2013; · 2.07 Impact Factor
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    ABSTRACT: Proteins and peptides expressed in the prokaryotic system often form inclusion bodies. Solubilization and refolding procedures can be used for their recovery, but this process remains difficult. One strategy for improving the solubility of a protein of interest is to fuse it to a highly soluble protein. To select a suitable fusion partner capable of solubilizing the aggregation-prone (inclusion body-forming) proteins and peptides, Escherichia coli thermostable proteins were identified and tested. Among them, trigger factor (TF) protein was selected because of its high expression and stability. Using an expression system based on fusion to TF, selected proteins and peptides that otherwise form inclusion bodies were expressed in soluble state and were purified like other soluble proteins. This system provides a convenient method for production of aggregation-prone proteins and peptides.
    BioTechniques 06/2008; 44(6):787-96. · 2.40 Impact Factor

Publication Stats

15 Citations
17.31 Total Impact Points

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Institutions

  • 2008–2014
    • Chosun University
      • • College of Medicine
      • • Research Center for Proteineous Materials (RCPM)
      Gwangju, Gwangju, South Korea
  • 2013
    • University of Rajshahi
      • Department of Genetic Engineering and Biotechnology
      Rājshāhi, Rajshahi Division, Bangladesh