Journal article
Npr2 null mutants show initial overshooting followed by reduction of spiral ganglion axon projections combined with near-normal cochleotopic projection
Cell and tissue research, Vol.378(1), pp.15-32
10/2019
DOI: 10.1007/s00441-019-03050-6
PMCID: PMC7243364
PMID: 31201541
Abstract
Npr2 (natriuretic peptide receptor 2) affects bifurcation of neural crest or placode-derived afferents upon entering the brain stem/spinal cord, leading to a lack of either rostral or caudal branches. Previous work has shown that early embryonic growth of cochlear and vestibular afferents is equally affected in this mutant but later work on postnatal Npr2 point mutations suggested some additional effects on the topology of afferent projections and mild functional defects. Using multicolor lipophilic dye tracing, we show that absence of Npr2 has little to no effect on the initial patterning of inner ear afferents with respect to their dorsoventral cochleotopic-specific projections. However, in contrast to control animals, we found a variable degree of embryonic extension of auditory afferents beyond the boundaries of the anterior cochlear nucleus into the cerebellum that emanates only from apical spiral ganglion neurons. Such expansion has previously only been reported for Hox gene mutants and implies an unclear interaction of Hox codes with Npr2-mediated afferent projection patterning to define boundaries. Some vestibular ganglion neurons expand their projections to reach the cochlear apex and the cochlear nuclei, comparable to previous findings in Neurod1 mutant mice. Before birth, such expansions are reduced or lost leading to truncated projections to the anteroventral cochlear nucleus and expansion of low-frequency fibers of the apex to the posteroventral cochlear nucleus.
Details
- Title: Subtitle
- Npr2 null mutants show initial overshooting followed by reduction of spiral ganglion axon projections combined with near-normal cochleotopic projection
- Creators
- Hannes Schmidt - 0000 0001 2190 1447 grid.10392.39 Interfaculty Institute of Biochemistry University of Tübingen Tübingen GermanyBernd Fritzsch - 0000 0004 1936 8294 grid.214572.7 Department of Biology & Department of Otolaryngology, CLAS University of Iowa 128 Jefferson Avenue Iowa City IA 52242 USA
- Resource Type
- Journal article
- Publication Details
- Cell and tissue research, Vol.378(1), pp.15-32
- DOI
- 10.1007/s00441-019-03050-6
- PMID
- 31201541
- PMCID
- PMC7243364
- NLM abbreviation
- Cell Tissue Res
- ISSN
- 0302-766X
- eISSN
- 1432-0878
- Publisher
- Springer Berlin Heidelberg; Berlin/Heidelberg
- Grant note
- R01 AG060504 / NIH/NIA SCHM 2371/1 / Deutsche Forschungsgemeinschaft (http://dx.doi.org/10.13039/501100001659) FE 438/6-1 / DFG
- Language
- English
- Date published
- 10/2019
- Academic Unit
- Iowa Neuroscience Institute; Biology; Craniofacial Anomalies Research Center
- Record Identifier
- 9984070280102771
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