Phosphoinositide Lipids in Ocular Tissues.

Ammaji Rajala,Richard S Brush,Khuong Nguyen,Austin Mccauley,Raju V.S Rajala

doi:10.3390/biology9060125

Ammaji Rajala, Richard S Brush + Show 3 more

Open Access

https://doi.org/10.3390/biology9060125

Copy DOI

Abstract

Inositol phospholipids play an important role in cell physiology. The inositol head groups are reversibly phosphorylated to produce seven distinct phosphorylated inositides, commonly referred to as phosphoinositides (PIs). These seven PIs are dynamically interconverted from one PI to another by the action of PI kinases and PI phosphatases. The PI signals regulate a wide variety of cellular functions, including organelle distinction, vesicular transport, cytoskeletal organization, nuclear events, regulation of ion channels, cell signaling, and host–pathogen interactions. Most of the studies of PIs in ocular tissues are based on the PI enzymes and PI phosphatases. In this study, we examined the PI levels in the cornea, retinal pigment epithelium (RPE), and retina using PI-binding protein as probes. We have examined the lipids PI(3)P, PI(4)P, PI(3,4)P2, PI(4,5)P2, and PI(3,4,5)P3, and each is present in the cornea, RPE, and retina. Alterations in the levels of these PIs in mouse models of retinal disease and corneal infections have been reported, and the results of our study will help in the management of anomalous phosphoinositide metabolism in ocular tissues.

Highlights

Phosphoinositides are low-abundance lipids and constitute ~0.5% to 1% of the total phospholipid pool
Light passes through the cornea and the image is processed in the retina, whereas the retinal pigment epithelium (RPE) provides nourishment to the retina
Pathogens hijack the PI pathways and use them for entry and survival in During viral infection, pathogens hijack the PI pathways and use them for entry and survival in the host cell [20,21,22]. Consistent with these studies, we previously reported that corneal cells infected the host cell [20,21,22]. Consistent with these studies, we previously reported that corneal cells infected with Adenovirus 19 utilize class I phosphoinositide 3-kinase/Akt activation for viral pathogenesis [23]

Summary

Introduction

Phosphoinositides are low-abundance lipids and constitute ~0.5% to 1% of the total phospholipid pool. The free hydroxyl groups on the inositol ring undergo phosphorylation by PI kinases; the phosphorylation products are called phosphoinositides [2]. By the action of PI kinases and PI phosphatases, seven distinct phosphoinositide signaling molecules have been identified [1,2] (Figure 1). These seven distinct phosphoinositide signals regulate various cellular events, including vesicular trafficking, cytoskeletal organization, membrane fusion, phagocytosis, and cell survival [1,2,3]. The presence of PI signaling pathways, mainly the PI kinases and PI phosphatases in the cornea [5], retina, and RPE [3,6], has been reported previously.

Methods

Results

Conclusion