nlz gene family is required for hindbrain patterning in the zebrafish

This study describes the conserved niz gene family whose members encode unusual zinc finger proteins. In the zebrafish neurectoderm, both nIz1 and the newly isolated nIz2 are expressed in the presumptive hindbrain and midbrain/hindbrain boundary, where expression of nIz1 is dependent on pax2a. In addition, nIz2 is uniquely expressed more anteriorly, in the presumptive midbrain and diencephalon. Overexpression of NIz proteins during gastrula stages inhibits hindbrain development. In particular, ectopically expressed NIz1 inhibits formation of future rhombomeres 2 and 3 (r2, r3), whereas neighboring r1 and r4 are not affected. Conversely, simultaneous reduction of NIz1 and NIz2 protein function by expression of antisense morpholino-modified oligomers leads to expansion of future r3 and r5, with associated loss of r4. These data indicate that one function of the niz gene family is to specify or maintain r4 identity, and to limit r3 and r5 during hindbrain formation. (C) 2004 Wiley-Liss, Inc.