Expression of Islet1 marks the sensory and neuronal lineages in the mammalian inner ear

Kristen Radde-Gallwitz, Ling Pan, Lin Gan, Xi Lin, Neil Segil, Ping Chen

Research output: Contribution to journalArticlepeer-review

95 Scopus citations


Several basic helix-loop-helix (bHLH) genes have been shown to be essential for the generation of the auditory sensory hair cells or the spiral ganglion (SG) neurons that innervate the hair cells in the cochlea, as well as a variety of cell types in the other nervous systems. However, it remains elusive what cellular context-dependent mechanisms confer the inner ear-specific neuronal or sensory competency/identities. We explored the possibility that one of the mechanisms responsible for generating cellular diversity in the nervous system through cooperative action of bHLH and LIM-homeodomain (LIM-HD) transcriptional factors might also contribute to the inner ear-specific sensory and/or neuronal competency. Here, we show that Islet1 (Isl1), a LIM-HD protein, is expressed early in the otocyst in the region that gives rise to both the auditory sensory organ, the organ of Corti, and SG neurons. Subsequently, the expression of Isl1 is maintained in SG neurons but is transitory in the sensory lineage. At embryonic day 12 (E12) in mice, the expression of Isl1 marks distinctively the ventral portion of the nascent cochlear epithelium encompassing the primordial organ of Corti. At E13, Isl1 is maintained at relatively high levels in the sensory primordium while down-regulated in the other regions of the cochlear duct. As the sensory epithelium starts to differentiate, it is down-regulated in the entire cochlear epithelium. The expression of Isl1 in the developing inner ear reveals an early and likely a common step in the development of both sensory and neuronal lineages of the inner ear, and suggests its potential role in the inner ear-specific sensory and neuronal cell development.

Original languageEnglish (US)
Pages (from-to)412-421
Number of pages10
JournalJournal of Comparative Neurology
Issue number4
StatePublished - Sep 27 2004
Externally publishedYes


  • LIM-HD
  • Math1
  • Organ of Corti
  • Sensory hair cells
  • Spiral ganglion neurons
  • bHLH

ASJC Scopus subject areas

  • Neuroscience(all)


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