Review
The role of Atonal transcription factors in the development of mechanosensitive cells

https://doi.org/10.1016/j.semcdb.2013.03.010Get rights and content

Highlights

  • Atonal transcription factors specify mechanosensitive cells in vertebrates and invertebrates.

  • The genetic targets of atonal factors are beginning to be identified.

  • Atonal factors promote sensory cell regeneration in some vertebrates, but not mammals.

Abstract

Mechanosensation is an evolutionarily ancient sensory modality seen in all main animal groups. Mechanosensation can be mediated by sensory neurons or by dedicated receptor cells that form synapses with sensory neurons. Evidence over the last 15–20 years suggests that both classes of mechanosensory cells can be specified by the atonal class of basic helix-loop-helix transcription factors. In this review we discuss recent work addressing how atonal factors specify mechanosensitive cells in vertebrates and invertebrates, and how the redeployment of these factors underlies the regeneration of mechanosensitive cells in some vertebrate groups.

Section snippets

Atonal genes and mechanosensory cells

Two bHLH gene families are associated with sensory cells across metazoans–the achaete-scute and atonal families. Of these, the atonal genes are particularly strongly linked with the specification of photo- and mechanoreceptor cells [1]. The atonal gene was discovered in Drosophila as a proneural transcription factor for mechanoreceptive neurons and photoreceptor cells [2], [3]. Jellyfish atonal homologues are expressed in photoreceptive and mechanosensory cells [4]. In vertebrates, these two

Drosophila Atonal and the development of sensory neurons

Ch neurons form part of internal sense organs that mediate proprioception (Ch organs are typically located to respond to joint or body movement), and hearing and gravitaxis (the large Ch neuron array of Johnston's Organ in the antenna) [18]. During the formation of the precursors of these neurons within the ectoderm (sense organ precursors or SOPs), atonal functions as a ‘typical’ proneural gene in that its expression is necessary and sufficient for SOP specification [2]. It is transiently

The role of vertebrate Atoh1 genes in the development of mechanosensory hair cells

The developmental module that uses atonal family bHLH genes to regulate the development of mechanosensory cells is thought to be evolutionarily ancient [11]. As discussed above, invertebrates such as Drosophila use this module to generate intrinsically mechanosensitive neurons, whereas some vertebrate sensory systems have split the function of the mechanosensitive neuron into a sensory receptor cell (such as a hair cell or Merkel cell) that makes synaptic connections with a sensory neuron that

The role of Atoh1 in the regeneration of hair cells

Mammals are unable to regenerate their auditory hair cells after damage, and display only a very limited degree of regeneration in the vestibular system (reviewed in Ref. [104]). In contrast, non-mammalian vertebrates show robust hair cell regeneration after damage due to the proliferation and trans-differentiation of supporting cells. Non-mammalian vestibular sensory organs and the lateral line organs of teleosts also show a steady ongoing turnover of hair cells [105], [106]. Accordingly,

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