Eur J Anat, 19 (2): 189-195 (2015)

Caspase-2 immunohistochemistry in differentiating cells during mouse cephalic development

Nathalie Vanmuylder, Marie Lejong, Myriam Choa-Duterre and Stéphane Louryan

Laboratoire dâ??Anatomie, Biomécanique et Organogenèse, Université Libre de Bruxelles, Faculté de Médecine, Bruxelles, Belgium

ABSTRACT Caspases are proteases primarily involved in the process of apoptosis; however, caspases can exert non-apoptotic functions. The purpose of this work was to use immunohistochemistry to analyse the expression sites of caspase-2 during normal mouse cephalic development and in embryos exposed to irradiation. Control embryos from embryonic day 9 (E9) to E17 were analysed, and E9 and 10 irradiated embryos were removed and observed after administration of 2 Gy irradiation at embryonic day 9. Surprisingly, not only apoptotic cells expressed caspase-2. In addition, numerous cell populations in normal and experimental embryos displayed transient but intense caspase-2 immunoreactivity, with nuclear and cytoplasmic localisation. This immunoreactivity was not observed with caspase-3 and -9 antibodies.Cranial neural crest cells, premuscular blastemata, cartilage, teeth, the heart, the eye and some other structures displayed caspase-2 expression, with progressive changes during embryonic development. These changing patterns evoke progressive waves of cell differentiation in specific cell populations. Little is known regarding the non-apoptotic functions of caspase-2. Despite the difficulty in understanding the role of this protease during cell differentiation, the fact that caspase-2 is known to prevent DNA damage and to protect the cell cycle could be closely associated with our observations, which point to the need for further research, particularly in caspase-2 knockout mice.

Keywords: Caspase-2, Embryo, Development, Head, Cell differentiation