Neurotrophic activity of an homeobox peptide.

The sixty aminoacid-long peptide corresponding to the homeobox of Antennapedia (pAntp) translocates through the membrane of neurons in culture and reaches their nuclei. This process is followed by an enhanced morphological differentiation of the neurons. Internalization by neurons is 4-fold that observed with fibroblasts. This difference is abolished upon treatment with Endo-N which specifically cleaves alpha, 2-8 bounds in polysialic acid (PSA). To understand the mode of action of the peptide, the authors constructed three mutants modified in their capacity to specifically bind promoters and/or to translocate through the cell membrane. The biological properties of the mutants demonstrate that the neurotrophic action of pAntp requires its internalization and the integrity of its specific DNA-binding capacity.