EXPRESSION OF THE NEUROFIBROMATOSIS-2 (NF2) GENE ISOFORMS DURING RAT EMBRYONIC-DEVELOPMENT

The neurofibromatosis 2 (NF2) gene product, merlin, encodes a 595 amin o acid protein with sequence similarity to a family of proteins linkin g cell membrane proteins to the cytoskeleton. Two isoforms of merlin h ave been described which differ by the presence (type 2 merlin) or abs ence (type 1 merlin) of exon 16 sequences inserted into the extreme ca rboxyl terminus of the protein. To determine the role of this importan t negative growth regulator during normal embryonic development, the e xpression of these two merlin isoforms was examined at representative stages of rat embryogenesis and in adult tissues. Partial sequence ana lysis of the rat merlin gene demonstrated striking amino acid identity to the published mouse and human merlin gene sequences. In situ hybri dization and RT-PCR analyses demonstrated that rat merlin is widely ex pressed during embryogenesis and early postnatal life in most tissues but becomes restricted to the brainstem, cerebellum, dorsal root gangl ia, spinal cord, adrenal gland and testis in adult animals. The elucid ation of the pattern of merlin gene expression in adult and embryonic tissues provides the foundations for future studies aimed at determini ng the function(s) of this protein during cell differentiation and emb ryonic development.