Cristiana de Carvalho Ribeiro1, Antonio Henrique Baccin Martins3, Rodrigo Ribeiro Resende1, Dulce Elena Casarini2, João Bosco Pesquero3 and Henning Ulrich1*. *Corresponding author.

Kinins are vasoactive peptides generated upon proteolytic cleavage of low- and high-molecular weight kininogens by kallikreins. These peptides have a well established signaling role in inflammation and homeostasis. Nevertheless, emerging evidence suggests that bradykinin and other kinins are stored in the central nervous system and may act as neuromediators in the nociceptive response and as differentiation factor in P19 embryonal carcinoma cells. Bradykinin has been shown to promote neuronal differentiation of this cell line by using an autocrine loop of receptor activation (Martins et al. J. Biol. Chem. 280, 19576-19586, 2005). In this abstract we report that in addition to secretion of increasing concentration of bradykinin into the culture medium, reaching maximal values of 0.7 nmol/106 cells  when neuronal differentiation was complete, metabolites arising from bradykinin hydrolysis were also detected. The breakdown products bradykinin-(1-5), bradykinin-(1-7) and des-Arg9-bradykinin were quantified by reversed-phase HPLC and shown to be 1.2 nmol/106 cells, 0.4 nmol/106 cells, and 0.9 nmol/106 cells, respectively. The presence of these peptides resulting from bradykinin hydrolysis demonstrates the functional expression of enzymes of the kallikrein-kinin system, including carboxypeptidases M and N, angiotensin converting enzyme and neutral endopeptidase. Further studies must be performed to establish a connection between expression and activity pattern of these enzymes and the outcome of neuronal differentiation.
Supported by FAPESP, CNPq and CAPES.