Elsevier

Developmental Biology

Volume 253, Issue 1, 1 January 2003, Pages 150-162
Developmental Biology

Regular Article
Novel Activities of Mafb Underlie Its Dual Role in Hindbrain Segmentation and Regional Specification

https://doi.org/10.1006/dbio.2002.0864Get rights and content
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Abstract

The bZip transcription factor Mafb is expressed in two segments of the developing vertebrate hindbrain: the rhombomeres 5 and 6. Loss of Mafb expression in the mouse mutant kreisler leads to elimination of r5 and to alterations of r6 regional identity. Here, we further investigated the role of Mafb in hindbrain patterning using gain-of-function experiments in the chick embryo. Our work has revealed novel functions for Mafb, including a positive autoregulatory activity, the capacity to repress Hoxb1 expression, and the capacity to synergise with or antagonise Krox20 activity. These different activities appear to be spatially restricted in the hindbrain, presumably due to interactions with other factors. Reinvestigation of the kreisler mutation indicated that it also results in an ectopic activation of Mafb in rhombomere 3, accounting for the previously described molecular alterations of this rhombomere in the mutant. Together, these data allow us to refine our view of the dual function of Mafb in both segmentation and specification of anteroposterior identity in the hindbrain.

Keywords

hindbrain
rhombomere
segmentation
Mafb
Hox
Eph
kreisler
Krox20

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1

Current address: Vertebrate Development Laboratory, Cancer Research UK, 44 Lincoln's Inn Fields, London, WC2A 3PX, UK.

2

To whom correspondence should be addressed. Fax: +33 1 44 32 39 88. E-mail: [email protected].