The miRNA-34a/Sirt1/p53 pathway in a rat model of lens regeneration

Background: There are many molecular factors involved in Wolffian and corneal lens regeneration, but few in lens regeneration by lens epithelial cells (LECs) in mammals. Silent information regulator 1 (Sirt1) has a variety of physiological functions, such as a transport hub, and is involved in pathological conditions. We studied the expression of the microRNA (miRNA)-34a/Sirt1/tumor protein p53 (p53) pathway in a rat model of lens regeneration. Methods: We performed extracapsular lens extraction in 42 healthy female Sprague-Dawley rats. Slit lamp observation was performed at 3, 7, 14, 21, 30, 60 and 90 days postoperatively, and the rats were killed humanely by cervical dislocation at 30, 60 and 90 days postoperatively to remove the eyeballs. We performed semiquantitative immunofluorescence analysis of Sirt1, p53, alpha-smooth muscle actin (alpha-SMA) and fibronectin (fn), and real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) to detect the relative expressions of miRNA-34a, Sirt1, p53, aquaporin 0 (AQP 0), gamma A-crystallin, and beaded filament structural protein 1 (BFSP1) mRNA in the lens and posterior capsule. Results: The posterior capsule wrinkled at 3 days and it increased at 7 days. At 14 days, pearl-like opacification appeared under the capsule, with increasing shrinkage. Greater mass-like proliferators in size and number accumulated under the capsule and at the equator after 21 days. A regenerated lens developed in the central depression of the capsule at 30 days, slightly protruding from it. Despite being thickened at 60 days, the central depression persisted, with a smaller change at 90 days than at 60 days. Although the relative mRNA expression of miRNA-34a and p53 in the lens and posterior capsule decreased over time (P=0.000), that of Sirt1 increased (P<0.01). alpha-SMA was uniformly expressed in the crystals and gradually decreased, while fn expression gradually increased. Conclusions: miRNA-34a expression decreased and Sirt1 expression increased during lens regeneration. Furthermore, p53 expression decreased, thus reducing apoptosis. Therefore, Sirt1 acted as a key factor in the pathway, and played a protective role in lens regeneration.