State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China.
PLoS One. 2013;8(1):e53919. doi: 10.1371/journal.pone.0053919. Epub 2013 Jan 10.
Pax6 is a pivotal transcription factor that plays a role during early eye morphogenesis, but its expression and function in eyelid development remain unknown. In this study, the expression patterns of Pax6 mRNA and protein were examined in the developing mouse eyelid at embryonic days 14.5, 15.5, and 16.5. The function of Pax6 in eyelid development was determined by comparing it to that in the eyes-open-at-birth mutant mouse. In the normally developing eyelid, Pax6 and Pax6(5a) mRNA levels were low at E14.5, increased at E15.5, and then declined at E16.5, accompanied by a change in the Pax6/Pax6(5a) ratio. Pax6 protein was mainly located in the mesenchyme and conjunctiva. It was expressed at low levels in the epidermis at E14.5, severely reduced at E15.5, but re-expressed in the keratinocyte cells of the periderm at E16.5. In contrast, Pax6 and the Pax6/Pax6(5a) ratio were considerably higher with strong nuclear expression in the mutant at E15.5. Next, we examined the relationship of Pax6 to epidermal cell proliferation, migration, and the associated signalling pathways. The Pax6 protein in the developing eyelid was negatively correlated with epidermal cell proliferation but not migration, and it is in contrast to the activation of the EGFR-ERK pathway. Our in vivo data suggest that Pax6 expression and the Pax6/Pax6(5a) ratio are at relatively low levels in the eyelid, and acting as a transcription factor, Pax6 is required for the initiation of eyelid formation and for differential development of the keratinised cells in the closed eyelid. The Pax6 protein is likely to be controlled by the EGFR-ERK pathways. An abnormal increase in Pax6 expression and the Pax6/Pax6(5a) ratio due to alteration of the pathway activity could suppress epidermal cell proliferation leading to the eyes-open-at-birth defect. This study offers insight into the function of the Pax6 protein in eyelid development.
Pax6 是一种关键的转录因子，在眼睛形态发生的早期发挥作用，但它在眼睑发育中的表达和功能尚不清楚。在这项研究中，在胚胎 14.5、15.5 和 16.5 天的发育中的小鼠眼睑中检查了 Pax6 mRNA 和蛋白的表达模式。通过比较出生时睁眼突变小鼠，确定了 Pax6 在眼睑发育中的功能。在正常发育的眼睑中，Pax6 和 Pax6(5a)mRNA 水平在 E14.5 时较低，在 E15.5 时增加，然后在 E16.5 时下降，同时 Pax6/Pax6(5a) 比值发生变化。Pax6 蛋白主要位于间充质和结膜中。在 E14.5 时表皮中表达水平较低，在 E15.5 时严重减少，但在 E16.5 时重新表达于周皮的角蛋白细胞中。相比之下，在突变体中，Pax6 和 Pax6/Pax6(5a) 比值在 E15.5 时明显较高，且核表达较强。接下来，我们研究了 Pax6 与表皮细胞增殖、迁移和相关信号通路的关系。发育中的眼睑中的 Pax6 蛋白与表皮细胞增殖呈负相关，但与迁移无关，与 EGFR-ERK 通路的激活相反。我们的体内数据表明，Pax6 的表达和 Pax6/Pax6(5a) 比值在眼睑中相对较低，作为转录因子，Pax6 对于眼睑形成的启动和闭合眼睑中角化细胞的差异发育是必需的。Pax6 蛋白可能受 EGFR-ERK 通路的控制。由于通路活性的改变导致 Pax6 表达和 Pax6/Pax6(5a) 比值的异常增加，可能会抑制表皮细胞的增殖，导致出生时睁眼缺陷。这项研究提供了对 Pax6 蛋白在眼睑发育中的功能的深入了解。
