Abstract
Purpose :
Megalin (also known as Lrp2) is a member of the low-density lipoprotein receptor family and is involved in the transport and uptake of a variety of molecules including nutrients, hormones and their carrier proteins, and signaling molecules. This study is aimed to investigate the expression and the role of megalin/LRP2 in photoreceptor cells.
Methods :
The expression of Lrp2 in mouse and human eyes were examined by immunohistrochemitry. The expression of Lrp2 mRNA was conducted in mouse photoreceptor line 661W cells. Lrp2-shRNA was transfected into 661W cell to knock down (KD) Lrp2 gene. The cells were then stimulated with LPS, hydrogen peroxide, and serum starvation. Cell viability was examined using the cell counting kit-8 (CCK8) assay. Expression of iNOS, IL-6, LC3, mTOR, and Nrf2 was examined by real-time qPCR.
Results :
Lrp2 was detected in Müller, RPE and photoreceptors in mouse and human eyes and 661W cells.Approximately 80% knock down of Lrp2 mRNA was achieved in 661W cells, which was further confirmed at protein level by western blot. LPS and hydrogen peroxide treatment significantly reduced Lrp2 expression in 661W cells. Knockdown Lrp2 reduced the proliferation of 661W cells under normal conditions, and impaired cell viability under oxidative stress. Lrp2-KD cells expressed lower levels of LC3, mTOR, but higher levels of Nrf2 following starvation and hydrogen peroxide treatment. Lrp2 konckdown reduced LPS-induced upregulation of iNOS and IL-6 in 661W cells.
Conclusions :
Photoreceptors express high levels of Lrp2, which may be involved in the inflammatory and autophagy pathways in photoreceptors under disease conditions.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.