Abstract
Purpose :
Retinitis pigmentosa (RP), characterized by the gradual loss of rod and cone photoreceptors that eventually leads to blindness, is the most common inherited retinal disorder, affecting more than 2.5 million people worldwide. However, the underlying pathogenesis of RP remains unclear and there is no effective cure for RP. Mutations in the Mer receptor tyrosine kinase (MerTK) gene induce the phagocytic dysfunction of retinal pigment epithelium (RPE) cells, leading to RP. Studies have indicated that filamentous actin (F-actin)—which is regulated by chaperonin-containing TCP1 subunit 5 (CCT5)—plays a vital role in phagocytosis in RPE cells. However, whether CCT5/F-actin signaling is involved in MerTK-associated RP remains largely unknown. Therefore, the present study explored the relationship between CCT5, F-actin, and RP, and the potential molecular mechanism underlying this disease.
Methods :
In the present study, we specifically knocked down MerTK and CCT5 through siRNA transfection and upregulating CCT5 using CCT5-specific lentiviral vectors (CCT5-Le), then examined the expression of CCT5, F-actin, cofilin, LIMK1, and SSH1, the arrangement of F-actin, the cell proliferation, migration, and phagocytic function of human primary RPE (HsRPE) cells.
Results :
We found that MerTK downregulation inhibited cell proliferation, migration, and phagocytic function; significantly decreased the expression of F-actin; and disrupted the regular arrangement of F-actin. Importantly, our findings firstly indicate that CCT5 interacts with F-actin and is inhibited by MerTK siRNA in HsRPE cells. Upregulating CCT5 using CCT5-Le rescued the cell proliferation, migration, and phagocytic function of HsRPE cells under MerTK-associated RP by increasing the expression of F-actin and restoring its regular arrangement via the LIMK1/cofilin, but not the SSH1/cofilin, pathway.
Conclusions :
In conclusion, CCT5 protects against MerTK-associated RP in RPE cells by interacting with F-actin and activating the LIMK1/cofilin pathway. This finding provide a new perspective for research into the mechanisms underlying MerTK-associated RP and provide a new direction for future studies of the molecular mechanisms of RP pathogenesis.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.