The Effect Of Cochlea Specific Knockout FGF13 On Auditory Function Of Mice And Its Influence On Spiral Ganglion Cells And Hair Cells

Fibroblast growth factor homologous factors?FHFs?,as a kind of special type of fibroblast growth factor?FGF?,play widely roles in the fields of cardiovascular,nervous system,cancer and so on,which have attracted much attention.A series of studies have found that the loss of function mutation of fgf13 gene can lead to the occurrence of borjeson-forssman-lehmann syndrome?BFLS?,Widervanck syndrome and congenital hypertrichosis.Through the study of literature,we found that the onset of hearing loss often occurred in patients with these syndromes.But what is the role of FGF13 in the hearing and whether the occurrence of hearing loss is related to FGF13abnormalities,are unclear at present.Based on previous studies about the role of FGF13 and our preliminary experimental results,we propose the following hypothesis:FGF13 may play an important role in auditory function and its abnormalities in expression or function may be related with the occurrence of hearing loss.In order to verify this hypothesis,this subject first generated cochlea specific FGF13 knockout mice,and detected the effects of FGF13knockout on auditory function at whole body level.Then we explored the expression pattern of FGF13 in cochlea at tissue level,finally we detected the influences of FGF13 knockout on cochlea spiral ganglion neurons and hair cells at cellular level to explore its possible mechanism.This study will provide important experimental data for revealing the role of FGF13 in auditory function as well as its possible mechanism,and theoretical basis for the correlation of FGF13 and hearing loss,which have important significance for basic research and clinical study.Objective:To detect the role of FGF13 in auditory function and its effects on spiral ganglion neurons and hair cells by generating and using cochlea specific FGF13 knockout mice.Methods:?1?Crossing FGF13-flox mice with Atoh1-cre mice to obtain cochlea specific knockout FGF13 mice?Atoh1-FGF13?.?2?Using mouse tail genotyping method and real-time quantitative PCR?qPCR?technique to identify and evaluate the FGF13 knockout efficiency.?3?Using the auditory brainstem response?ABR?and the distorted product otoacoustic emission technique?DPOAE?to detect the auditory function of mice,and to observe whether FGF13 knockout is related to the onset of hearing loss.?4?qPCR technique and immunofluorescence staining were used to detect the expression pattern of FGF13 in cochlea.?5?Using immunohistochemistry and whole-mount staining to detect the effects of cochlea FGF13 knockout on spiral ganglion neurons?SGNs?and hair cells?HCs?.Results:?1?We obtained the cochlear specific FGF13 knockout mice,and the qPCR test results showed that the FGF13 m RNA in cochlea was significantly reduced,suggesting that the knockout effect was good.?2?ABR test results showed that the hearing thresholds of FGF13homozygous mice(FGF13^-/-)were significantly increased,while those of results of DPOAE test showed that there was no obvious damage to the function of outer hair cells in FGF13^-/-mice.?3?FGF13 was highly expressed in the cytoplasm and cytomembrane of cochlea spiral ganglion neurons and hair cells in mice,and among the several sub-types of FGF13,FGF13VY sub-type was highest expressed in cochlea.?4?The density of spiral ganglion neurons in FGF13^-/-mice was significantly decreased,while the morphology and structure of hair cells showed no significant abnormalities.Conclusion:Cochlea knockout FGF13 can cause hearing loss in mice,and ABR thresholds were significantly increased at 8-32 KHz frequency,while there were no obvious anomalies in DPOAE detection.The density of spiral ganglion neurons was decreased,but the morphology and structure of hair cells showed no significant changes,suggesting that knockout FGF13may cause auditory abnormalities by affecting the spiral ganglion neurons.