Nlz belongs to a family of zinc-finger-containing repressors and controls segmental gene expression in the zebrafish hindbrain

Abstract

The zebrafish nlz gene has a rostral expression limit at the presumptive rhombomere (r) 3/r4 boundary during gastrula stages, and its expression progressively expands rostrally to encompass both r3 and r2 by segmentation stages, suggesting a role for nlz in hindbrain development. We find that Nlz is a nuclear protein that associates with the corepressor Groucho, suggesting that Nlz acts to repress transcription. Consistent with a role as a repressor, misexpression of nlz causes a loss of gene expression in the rostral hindbrain, likely due to ectopic nlz acting prematurely in this domain, and this repression is accompanied by a partial expansion in the expression domains of r4-specific genes. To interfere with endogenous nlz function, we generated a form of nlz that lacks the Groucho binding site and demonstrate that this construct has a dominant negative effect. We find that interfering with endogenous Nlz function promotes the expansion of r5 and, to a lesser extent, r3 gene expression into r4, leading to a reduction in the size of r4. We conclude that Nlz is a transcriptional repressor that controls segmental gene expression in the hindbrain. Lastly, we identify additional nlz-related genes, suggesting that Nlz belongs to a family of zinc-finger proteins.

Rostral hindbrain patterning involves the direct activation of aKrox20transcriptional enhancer by Hox/Pbx and Meis factors

“…7B,C). The existence of such a negative regulation is consistent with the inactivation of Hoxa1, which results in an extension of the anterior domain of Krox20 into prospective r4 Rossel and Capecchi, 1999), and with the repressive activity of Nlz family members on Krox20 expression (Runko and Sagerström, 2003;Hoyle et al, 2004).…”

Zeppo1 is a novel metastasis promoter that repressesE-cadherinexpression and regulates p120-catenin isoform expression and localization

“…We therefore named Znf703 and Znf503 as Zeppo1 (Zinc finger elbow-related proline domain protein 1) and Zeppo2, respectively. Zpo1 and Zpo2 are also orthologs of the zebrafish Nlz1 (Runko and Sagerstrom 2003) and Nlz2 genes, respectively. Zpo1 and Zpo2 proteins are 54% identical.…”

“…Drosophila elbow and zebrafish Nlz1 proteins interact in vitro with the transcriptional corepressor Groucho (Dorfman et al 2002;Runko and Sagerstrom 2003). There are at least five members of the Groucho-related gene (Grg) family in mice (Gasperowicz and Otto 2005).…”

A novel role for Pax6 in the segmental organization of the hindbrain

“…Other TFs, such as Pbx/Meis, are also essential for hindbrain patterning via their synergistic activities with Hox factors (Aamar and Frank, 2004;Elkouby et al, 2012;Vlachakis et al, 2001;Wassef et al, 2008). Additional factors also modulate the expression of these TFs, such as Nab and Nlz (also known as Neurl1a), which colocalize with Krox20 but repress its transcription, leading to Krox20 restriction to the correct rhombomeres (García-Gutiérrez et al, 2011;Mechta-Grigoriou et al, 2000;Runko and Sagerström, 2003). Finally, Eph-ephrin signaling acts at the rhombomere interface and restricts cell intermixing by mediating repulsion.…”