Revisiting the Daily Timing of POS Phagocytosis

Antonio E Paniagua; Harjas S Sabharwal; Kausalya Kethu; Andrew W Chang; David S Williams

doi:10.1007/978-3-031-27681-1_75

Revisiting the Daily Timing of POS Phagocytosis

Adv Exp Med Biol. 2023:1415:515-519. doi: 10.1007/978-3-031-27681-1_75.

Authors

Antonio E Paniagua¹, Harjas S Sabharwal², Kausalya Kethu², Andrew W Chang², David S Williams³

Affiliations

¹ Departments of Ophthalmology and Neurobiology, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA. paniagua@ucla.edu.
² Departments of Ophthalmology and Neurobiology, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
³ Departments of Ophthalmology and Neurobiology, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA. dswilliams@ucla.edu.

PMID: 37440080
DOI: 10.1007/978-3-031-27681-1_75

Abstract

Retinal pigment epithelium (RPE) cells daily ingest the tips of the photoreceptor outer segments (POSs), with phagosome number varying throughout a 24-h cycle. A major focus in the literature has been on a peak in phagosome concentration shortly after lights-on. Moreover, this peak has frequently been inferred to represent a peak in POS tip ingestion. Here, we have reviewed old and new literature on the daily cycle of phagosome number in the RPE and conclude that there is more variation in the timing of phagosome concentration peaks than is currently acknowledged. We also discuss that phagosome quantity is affected by the rate of phagosome degradation as well as the rate of ingestion; given that phagosome half-life may not be constant throughout the daily cycle, maximal POS ingestion may not necessarily coincide with a peak in phagosome concentration.

Keywords: Daily rhythm; Phagocytosis; Phagosome; Photoreceptor outer segment; RPE.

MeSH terms

Cells, Cultured
Neurons
Phagocytosis*
Phagosomes / metabolism
Retinal Photoreceptor Cell Outer Segment
Retinal Pigment Epithelium*

Grants and funding

R01 EY033035/EY/NEI NIH HHS/United States