| Budget Amount *help |
¥15,300,000 (Direct Cost: ¥15,300,000)
Fiscal Year 2004: ¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 2003: ¥7,900,000 (Direct Cost: ¥7,900,000)
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| Research Abstract |
The mammalian inner ear consists of six distinct sensory organs : three cristae of the semicircular canals, two maculae of the saccule and utricle, and the organ of Corti of the cochlea. Despite its complexity, the inner ear derives from a simple cyctic structure known as an otocyst. However, molecular mechanisms underlying inner ear development are largely unknown. To identify molecule(s) involved in the formation and/or further differentiation of the otocyst, we isolated a secreted molecule, OC29, from a rat otocyst cDNA library by the signal sequence trap method. OC29 was revealed to be a rat homologue of human WFIKKN. OC29 is preferentially expressed in the developing inner ear and dorsal neural tube. In the inner ear, the expression of OC29 is first detectable at embryonic day 11.5 (E11.5), broadly in the dorsolateral region of the otocyst, which gives rise to the vestibular organ. At E12.5, the expression of OC29 becomes restricted to the presumptive sensory organ, mainly to the BMP4-positive presumptive cristae, and expression becomes reduced at later stages. These results suggested that OC29 may have a role in the early development of the inner ear sensory organ, particularly in the formation of the cristae of the semicircular canals.
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