DLX5 Regulates Development of Peripheral and Central Components of the Olfactory System

Abstract

Induction, neurogenesis, and synaptogenesis of the olfactory bulb are thought to require interactions with the olfactory epithelium. The Dlx family of homeobox genes is expressed in both the olfactory bulb and olfactory epithelium. In particular, Dlx5 is expressed in the olfactory placode, olfactory epithelium, and local circuit neurons of the olfactory bulb. Here we analyzed mice lacking DLX5 function. The Dlx5-/- mutation reduces the size of the olfactory epithelium. Although some olfactory neurons are formed, they fail to generate olfactory axons that innervate the olfactory bulb. Despite the lack of innervation, the olfactory bulb forms, and neurogenesis of projection and local circuit neurons proceeds. However, the mutation has a cell-autonomous effect on the ability of neural progenitors to produce olfactory bulb local circuit neurons, with granule cells more severely affected than periglomerular cells. In addition, the mutation has a noncell-autonomous effect on the morphogenesis of mitral cells.

Identification and characterization of a novel transcript down‐regulated in Dlx1/Dlx2 and up‐regulated in Pax6 mutant telencephalon

“…In the developing subpallium (future basal ganglia) Dlx1 and Dlx2 are expressed largely in the proliferating cells of the ventricular and subventricular zone (SVZ), whereas Dlx5 and Dlx6 are expressed in progressively more differentiated cells (Bulfone et al, 1993;Porteus et al, 1994;Anderson et al, 1997b;Eisenstat et al, 1999), suggesting that this gene family is involved in the regulation of different stages in the production of forebrain cells. This hypothesis is supported by the differentiation defects observed in Dlx mutants (Anderson et al, 1997a,b;Long et al, 2003;Perera et al, 2004).…”

Deletion of voltage‐gated channel affects glomerular refinement and odorant receptor expression in the mouse olfactory system

“…At the same time, each organ can develop independently in vivo or in vitro in the absence of normal pathfinding cues. For example, OSNs can fasciculate or even regenerate following complete surgical bulbectomy or in mouse genetic models that lack the OB or lack interactions between the OB and OE, and they can also project into foreign target tissues (Graziadei et al, 1978;Long et al, 2003;St. John et al, 2003;Storan and Key, 2004).…”

Dlx Homeobox Genes Promote Cortical Interneuron Migration from the Basal Forebrain by Direct Repression of the Semaphorin Receptor Neuropilin-2

“…There are distinct boundaries of Dlx1 and Dlx2 expression at the pallial-subpallial boundary (1). Insights into the functional role of Dlx genes in development have been primarily gained from analysis of the phenotypes of mice with targeted deletions of Dlx1/Dlx2 (5)(6)(7)(8), Dlx5 (9), and Dlx5/Dlx6 (10). The single Dlx1 and Dlx2 knockouts have relatively normal forebrain development at birth, which is consistent with functional redundancy between Dlx1 and Dlx2 in this anatomic region (1,4).…”