A NOVEL CROTAMINE FUNCTION OBSERVED IN THE MOUSE EMBRYONIC STEM CELLS

KERKIS, I.(1), KERKIS, A.(1), RÁDIS-BAPTISTA, G.(2), OLIVEIRA, E. B.(3), YAMANE, T.(2)

(1)Dept. of Genetics, Institute of Bioscience, University of São Paulo, (2)Molecular Toxinology Lab., Butantan Institute, (3)Dept. of Biochemistry, Faculty of Medicine of Ribeirão Preto, University of São Paulo.

The venom arsenal developed by poisonous animals contains toxins that disrupt the prey homeostasis – a hunting strategy evolved during million of years. Not surprisingly, the toxic repertory encompasses polypeptides with very conserved structural domains able to mimic endogenous modulators and to interrupt cell function.  The toxin crotamine, a cationic peptide (4.4 kDa, pI >9.5) occurs in the venom of Crotalus durissus terrificus (South American rattlesnake). Its 3-D structure is not yet solved, but comparison of its primary amino acid sequence, and its predicted secondary structure, with other peptides constrained also by three cysteine bridges, indicates that it could adopt a spatial conformation similar to beta-defensins or knottins. Both conformation types include members of multiple functions such as ion channel modulators, antimicrobial peptides, and also cell growth factors. Using mouse embryonic stem (ES) cells we were able to detect a novel function of crotamine peptide that is typical of cell signaling modulators. The dual function of crotamine is essentially dependent of concentration in the cell culture medium. At the concentration above 10-4 M/ml crotamine was cytotoxic to undifferentiated ES cells. We also found that at day 3 of treatment with crotamine (10-6 M/ml -10-7 M/m) the differentiating ES cells produced cells of ectoderm origin (nerve cells). In addition, the Cy3-labelled crotamine was selectively included into the chromatin of proliferated ES cells. The role of crotamine in the regulation of ES cells proliferation and differentiation is discussed.

Support: FAPESP

CORRESPONDENCE TO:

Alexander Kerkis, Instituto de Biociências, USP - Rua do Matão 277/350, Cidade Universitária, São Paulo, SP, CEP: 05508-900, Brasil, Email: akerkis@usp.br