MERTK-Dependent Ensheathment of Photoreceptor Outer Segments by Human Pluripotent Stem Cell-Derived Retinal Pigment Epithelium

Research output: Contribution to journalResearch articleContributedpeer-review



Maintenance of a healthy photoreceptor-retinal pigment epithelium (RPE) interface is essential for vision. At the center of this interface, apical membrane protrusions stemming from the RPE ensheath photoreceptor outer segments (POS), and are possibly involved in the recycling of POS through phagocytosis. The molecules that regulate POS ensheathment and its relationship to phagocytosis remain to be deciphered. By means of ultrastructural analysis, we revealed that Mer receptor tyrosine kinase (MERTK) ligands, GAS6 and PROS1, rather than αVβ5 integrin receptor ligands, triggered POS ensheathment by human embryonic stem cell (hESC)-derived RPE. Furthermore, we found that ensheathment is required for POS fragmentation before internalization. Consistently, POS ensheathment, fragmentation, and internalization were abolished in MERTK mutant RPE, and rescue of MERTK expression in retinitis pigmentosa (RP38) patient RPE counteracted these defects. Our results suggest that loss of ensheathment due to MERTK dysfunction might contribute to vision impairment in RP38 patients.


Original languageEnglish
Pages (from-to)374-389
Number of pages16
JournalStem cell reports
Issue number3
Publication statusPublished - 10 Mar 2020

External IDs

PubMedCentral PMC7066375
Scopus 85081643637
ORCID /0000-0001-5624-1717/work/142239010
ORCID /0000-0002-0926-6556/work/142250475


Sustainable Development Goals


  • Cell Line, Human Embryonic Stem Cells/metabolism, Humans, Ligands, Mutation/genetics, Phagocytosis, Pluripotent Stem Cells/metabolism, Receptors, Vitronectin/metabolism, Retinal Photoreceptor Cell Outer Segment/enzymology, Retinal Pigment Epithelium/metabolism, c-Mer Tyrosine Kinase/genetics