首页|Math5 expression and function in the central auditory system

Math5 expression and function in the central auditory system

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The basic helix-loop-helix (bHLH) transcription factor Math5 (Atoh7) is required for retinal ganglion cell (RGC) and optic nerve development. Using Math5-lacZ knockout mice, we have identified an additional expression domain for Math5 outside the eye, in functionally connected structures of the central auditory system. In the adult hindbrain, the cytoplasmic Math5-lacZ reporter is expressed within the ventral cochlear nucleus (VCN), in a subpopulation of neurons that project to medial nucleus of the trapezoid body (MNTB), lateral superior olive (LSO), and lateral lemniscus (LL). These cells were identified as globular and small spherical bushy cells based on their morphology, abundance, distribution within the cochlear nucleus (CN), co-expression of Kv1.1, Kv3.1b and Kcnq4 potassium channels, and projection patterns within the auditory brainstem. Math5-lacZ is also expressed by cochlear root neurons in the auditory nerve. During embryonic development, Math5-lacZ was detected in precursor cells emerging from the caudal rhombic lip from embryonic day (E)12 onwards, consistent with the time course of CN neurogenesis. These cells co-express MOB and are post-mitotic. Math5 expression in the CN was verified by mRNA in situ hybridization, and the identity of positive neurons was confirmed morphologically using a Math5-Cre BAC transgene with an alkaline phosphatase reporter. The hindbrains of Math5 mutants appear grossly normal, with the exception of the CN. Although overall CN dimensions are unchanged, the lacZ-positive cells are significantly smaller in Math5 -/- mice compared to Math5 +/- mice, suggesting these neurons may function abnormally. The auditory brainstem response (ABR) of Math5 mutants was evaluated in a BALB/cJ congenic background. ABR thresholds of Math5 -/- mice were similar to those of wild-type and heterozygous mice, but the interpeak latencies for Peaks II-IV were significantly altered. These temporal changes are consistent with a higher-level

Math5cochlear nucleusAVCNPVCNmouseatonalMath1bHLHglobular bushy cellsspherical bushy cellsCochlear root neuronsauditory processingABR latencybinaural integrationinteraural intensity differenceinteraural time differencephase lockingcalyx of heldKv1.1Kv3.1Kcnq4MafBCre recombinasefluoro-goldtract-tracinginferior colliculusmultipolar cellsrhombic lipVENTRAL COCHLEAR NUCLEUSKV3.1 POTASSIUM CHANNELRETINAL GANGLION-CELLBRAIN-STEM LESIONSINFERIOR COLLICULUSMULTIPLE-SCLEROSISTRAPEZOID BODYROOT NEURONSHEARING-LOSSRHOMBIC-LIP

Saul SM、Brzezinski JA、Altschuler RA、Shore SE、Rudolph DD、Kabara LL、Halsey KE、Hufnagel RB、Zhou J、Dolan DF

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Univ Michigan, Dept Human Genet, Ann Arbor, MI 48109 USA

Univ Michigan, Dept Internal Med, Ann Arbor, MI 48109 USA

Univ Michigan, Kresge Hearing Res Inst, Ann Arbor, MI 48109 USA

Univ Cincinnati, Childrens Hosp Res Fdn, Coll Med, Cincinnati, OH 45229 USA

Univ Cincinnati, Dept Pediat, Coll Med, Cincinnati, OH 45229 USA

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2008

Molecular and cellular neurosciences

Molecular and cellular neurosciences

ISSN：1044-7431
年,卷(期)：2008.37(1)