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Author Notes:

Correspondence to: Ping Chen, Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA. pchen@cellbio.emory.edu.

We thank Paul Chen, Juan Llamas, and Welly Makmura for animal care; Seung-Jong Yoo, Jeffrey Saeks, and Connie Tang for technical assistance in cryosection preparation; Jane E. Johnson for Math1/GFP animals; Christine Petit and A. El-Amraoui for myosin VIIa antibody; Frank Middleton for Affymetrix microarray analysis; Matthew Holley for communications on expressions of otocyst-specific genes; and the Developmental Studies Hybridoma Bank for Isl1 antibody.


Research Funding:

Grant sponsor: National Institutes of Health; Grant number: EY013426; Grant number: DC04709; Grant number: DC004189; Grant number: DC005213.


  • Science & Technology
  • Life Sciences & Biomedicine
  • Neurosciences
  • Zoology
  • Neurosciences & Neurology
  • organ of Corti
  • spiral ganglion neurons
  • sensory hair cells
  • LIM-HD
  • bHLH
  • Math1
  • MATH1
  • GENE
  • MICE

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


Journal Title:

Journal of Comparative Neurology


Volume 477, Number 4


, Pages 412-421

Type of Work:

Article | Post-print: After Peer Review


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.

Copyright information:

© 2004 Wiley-Liss, Inc.

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