Hair cell regeneration or the expression of related factors that regulate the fate specification of supporting cells in the cochlear ducts of embryonic and posthatch chickens

Hair cells in posthatch chickens regenerate spontaneously through mitosis or the transdifferentiation of supporting cells in response to antibiotic injury. However, how embryonic chicken cochleae respond to antibiotic treatment remains unknown. This study is the first to indicate that unlike hair cells in post hatch chickens, the auditory epithelium was free from antibiotic injury (25-250 mg gentamicin/kg) in embryonic chickens, although FITC-conjugated gentamicin actually reached embryonic hair cells. Next, we examined and counted the cells and performed labeling for BrdU, Sox2, Atoh1/Math1, PV or p27(kip1) (triple or double labeling) in the injured cochlea ducts after gentamicin treatment at 2 h (h), 15 h, 24 h, 2 days (d), 3 d and 7 d after BrdU treatment in posthatch chickens. Our results indicated that following gentamicin administration, proliferating cells (BrdU+) were labeled for Atoh1/Math1 in the damaged areas 3d after gentamicin administration, whereas hair cells (PV+) renewed through mitosis (BrdU+) or direct transdifferentiation (BrdU-) were evident only after 5 d of gentamicin administration. In addition, Sox2 expression was up-regulated in triggered supporting cells at an early stage of regeneration, but stopped at the advent of mature hair cells. Our study also indicated that p27(kip1) was expressed in both hair cells and supporting cells but was down-regulated in a subgroup of the supporting cells that gave rise to hair cells. These data and the obtained dynamic changes of the cells labeled for BrdU, Sox2, Atoh1/Math1, PV or p27(kip1) are useful for understanding supporting cell behaviors and their fate specification during hair cell regeneration. (C) 2015 Elsevier B.V. All rights reserved.

孵化后的鸡的毛细胞在受到抗生素损伤时会通过有丝分裂或支持细胞的转分化自发再生。然而，胚胎期鸡的耳蜗如何应对抗生素处理仍然未知。本研究首次表明，与孵化后的鸡的毛细胞不同，胚胎期鸡的听觉上皮在（25 - 250毫克庆大霉素/千克）抗生素处理下未受损伤，尽管异硫氰酸荧光素标记的庆大霉素实际上到达了胚胎期毛细胞。接下来，我们在孵化后的鸡给予溴脱氧尿苷（BrdU）处理后2小时（h）、15小时、24小时、2天（d）、3天和7天，对庆大霉素处理后的受损耳蜗管进行细胞检查和计数，并对BrdU、Sox2、Atoh1/Math1、PV或p27(kip1)进行标记（三重或双重标记）。我们的结果表明，在给予庆大霉素后，增殖细胞（BrdU⁺）在庆大霉素给药3天后在受损区域被标记为Atoh1/Math1，而通过有丝分裂（BrdU⁺）或直接转分化（BrdU⁻）更新的毛细胞（PV⁺）仅在庆大霉素给药5天后才明显出现。此外，Sox2的表达在再生早期的被触发的支持细胞中上调，但在成熟毛细胞出现时停止。我们的研究还表明，p27(kip1)在毛细胞和支持细胞中均有表达，但在产生毛细胞的一部分支持细胞中下调。这些数据以及所获得的对BrdU、Sox2、Atoh1/Math1、PV或p27(kip1)标记的细胞的动态变化有助于理解毛细胞再生过程中支持细胞的行为及其命运特化。（C）2015爱思唯尔有限公司。保留所有权利。