Autophagy and Macropinocytosis: Keeping an Eye on the Corneal/Limbal Epithelia

Abstract

Autophagy and macropinocytosis are processes that are vital for cellular homeostasis, and help cells respond to stress and take up large amounts of material, respectively. The limbal and corneal epithelia have the machinery necessary to carry out both processes; however, autophagy and macropinocytosis are relatively understudied in these two epithelia. In this Perspectives, we describe the basic principles behind macropinocytosis and autophagy, discuss how these two processes are regulated in the limbal and corneal epithelia, consider how these two processes impact on the physiology of limbal and corneal epithelia, and elaborate on areas of future research in autophagy and macropinocytosis as related to the limbal/corneal epithelia.

Single-Cell RNA Transcriptome Helps Define the Limbal/Corneal Epithelial Stem/Early Transit Amplifying Cells and How Autophagy Affects This Population

“…Autophagy is the means by which cells adapt and respond to differing intrinsic and extrinsic cellular-related stress situations 67–70. Thus, it was not surprising that one of the most downregulated genes in the beclin 1 +/− scRNA-seq data set was histone H2ax (Fig.…”

Myelinosome Organelles in the Retina of R6/1 Huntington Disease (HD) Mice: Ubiquitous Distribution and Possible Role in Disease Spreading

“…Remarkably, in SH-SY5Y acceptor cells, myelinosomes clustered in large vacuoles located close to the plasma membrane. The aspect and the size (ø1.8 ± 0.20 μm ( n = 22)) of vacuoles harboring myelinosome vesicles resembled macropinosomes, which are the vacuoles formed during the macropinocytosis process [ 60 , 61 ]. Quantification analysis showed that each vacuole contained 2.37 ± 0.34 ( n = 27) myelinosomes, but several vacuoles harbored up to 8 myelinosomes.…”

Blue Light Induces Impaired Autophagy through Nucleotide-Binding Oligomerization Domain 2 Activation on the Mouse Ocular Surface

“…Autophagy is generally recognized to play an essential role in homeostasis by mediating the breakdown and conversion of defective organelles within the cells. Recent studies have shown that alterations in autophagy are involved in multiple ocular diseases, such as dry eye, pterygium, and retinal neurodegeneration [ 6 , 7 , 8 , 19 , 20 ]. Furthermore, autophagy plays an important role in blue-light-induced damage.…”

“…Autophagy is a conserved process that recycles defective cellular organelles and macromolecules. The process is upregulated in conditions such as oxidative stress, when cells need to remove unnecessary or dysfunctional components [ 8 ]. Recently, several studies have shown that blue light irradiation promotes apoptosis by the induction of impaired autophagy in RPE cells [ 6 ].…”