Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA.
Invest Ophthalmol Vis Sci. 2011 Jun 7;52(7):3962-9. doi: 10.1167/iovs.10-6866.
To examine the distribution and timing of expression of nonmuscle myosin IIB (nmMyH IIB) and the extraocular muscle (EOM)-specific myosin (EO-MyHC) during postnatal development of the rat extraocular muscles.
Whole orbits were collected from postnatal development day (P) 1 through P30 from Sprague-Dawley rats. Samples were analyzed by immunofluorescence microscopy and Western blot to examine the distribution and abundance of nmMyH IIB and EO-MyHC compared with other myosin isoforms and sarcomeric α-actinin. Polyclonal antibodies were produced to specifically detect EO-MyHC. Postnatal limb muscles were used as control.
Analysis of EOM morphology in the developing orbits indicates that the global and orbital layers are not evident until day P15. The distribution of nmMyH IIB changes between days P10 and P15 from a subsarcolemma distribution to an intrafiber distribution in the global layer. EO-MyHC appears by day p15, primarily in the orbital layer of the EOMs. Sarcomeric α-actinin was equally abundant in the EOMs at all stages. Fetal MyHC was the predominant isoform at day P1 but slowly diminished in abundance with age in a layer-specific manner.
These data demonstrate that significant changes occur in the EOMs from P10 to P15 and suggest that visual stimulation may play a role in the signals that regulate both nmMyH IIB and EO-MyHC developmental transitions. The pronounced distinctions of the orbital and global layers occurring by P15 establish the adult morphologic phenotype of the muscle.
研究非肌肉肌球蛋白 IIB（nmMyH IIB）和眼外肌（EOM）特异性肌球蛋白（EO-MyHC）在大鼠眼外肌出生后发育过程中的分布和表达时间。
从 Sprague-Dawley 大鼠出生后第 1 天（P）至第 30 天（P）收集整个眼眶。通过免疫荧光显微镜和 Western blot 分析样本，与其他肌球蛋白同工型和肌节α-辅肌动蛋白比较，研究 nmMyH IIB 和 EO-MyHC 的分布和丰度。制备了多克隆抗体来特异性检测 EO-MyHC。将出生后肢体肌肉用作对照。
对发育中眼眶 EOM 形态的分析表明，直到 P15 日，整体层和眶层才明显。nmMyH IIB 的分布在 P10 至 P15 之间从亚肌膜分布变为整体层中的纤维内分布。EO-MyHC 在 P15 日出现，主要存在于 EOM 的眶层中。肌节α-辅肌动蛋白在所有阶段在 EOM 中含量相等。胎儿 MyHC 是 P1 日的主要同工型，但随着年龄的增长以层特异性的方式逐渐减少。
这些数据表明，EOM 从 P10 到 P15 发生了重大变化，并表明视觉刺激可能在调节 nmMyH IIB 和 EO-MyHC 发育转变的信号中发挥作用。到 P15 日，眶层和整体层的明显区别建立了肌肉的成年形态表型。
