Reversibility Of Modifications Research Articles

Epigenetic plasticity of chromatin in embryonic and hematopoietic stem/progenitor cells: therapeutic potential of cell reprogramming

During embryonic development and adult life, the plasticity and reversibility of modifications that affect the chromatin structure is important in the expression of genes involved in cell fate decisions and the maintenance of cell-differentiated state. Epigenetic changes in DNA and chromatin, which must occur to allow the accessibility of transcriptional factors at specific DNA-binding sites, are regarded as emerging major players for embryonic and hematopoietic stem cell (HSC) development and lineage differentiation. Epigenetic deregulation of gene expression, whether it be in conjunction with chromosomal alterations and gene mutations or not, is a newly recognized mechanism that leads to several diseases, including leukemia. The reversibility of epigenetic modifications makes DNA and chromatin changes attractive targets for therapeutic intervention. Here we review some of the epigenetic mechanisms that regulate gene expression in pluripotent embryonic and multipotent HSCs but may be deregulated in leukemia, and the clinical approaches designed to target the chromatin structure in leukemic cells.

Pore-forming peptide of Entamoeba histolytica significance of positively charged amino acid residues for its mode of action

Amoebapore is a 77-residue pore-forming peptide from Entamoeba histolytica with antibacterial and cytolytic properties. It contains eight lysine residues and one histidine residue. Chemical modifications of amoebapore with various reagents affecting either both types of cationic residues or lysine and histidine residues separately resulted in virtually complete loss of pore-forming activity. The activity was restored by reversal of modifications. Whereas amoebapore was no longer capable of binding to phospholipid vesicles when its lysine residues were modified, the modification of the single histidine primarily affected oligomerization of the peptide upon membrane association.