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Fate‐mapping analysis using Rorb‐IRES‐Cre reveals apical‐to‐basal gradient of Rorb expression in mouse cochlea
Author(s) -
Li Chao,
Wang Yunfeng,
Wang Guangqin,
Lu Ying,
He Shunji,
Sun Yuwei,
Liu Zhiyong
Publication year - 2020
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/dvdy.111
Subject(s) - biology , cochlea , conditional gene knockout , inner ear , vestibular system , microbiology and biotechnology , embryonic stem cell , basal (medicine) , hair cell , anatomy , phenotype , neuroscience , gene , genetics , endocrinology , insulin
Background Conditional loss‐of‐function studies are widely conducted using the Cre/Loxp system because this helps circumvent embryonic or neonatal lethality problems. However, Cre strains specific to the inner ear are lacking, and thus lethality frequently occurs even in conditional knockout studies. Results Here, we report a Rorb‐IRES‐Cre knockin mouse strain in which the Cre recapitulates the expression pattern of endogenous Rorb (RAR‐related orphan receptor beta). Analysis of Rorb‐IRES‐Cre/+ ; Rosa26‐CAG‐LSL‐tdTomato/+ cochlear samples revealed that tdTomato was expressed at the apical turn only by E12.5. TdTomato was observed in the apical and middle turns but was minimally expressed in the basal turn at E15.5, E18.5, and P5. However, most of the auditory hair cells (HCs) and supporting cells (SCs) in all three turns were tdTomato+ at P15 and P30. Intriguingly, no tdTomato+ vestibular cells were detected until P5 and a few cells were present at P15 and P30. Finally, we also confirmed Rorb mRNA and protein expression in cochlear HCs and SCs at P30. Conclusions We reveal that Rorb expression exhibits an apical‐to‐basal gradient in cochleae. The cochlear‐specific and apical‐to‐basal‐gradient Rorb Cre activity should enable discrimination of gene functions in cochlear vs vestibular regions as well as low‐frequency vs high‐frequency regions in the cochlea.