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Researchers investigate epithelial cell-to-cell communication in the eye with new precision

Published on 22.3.2022
Tampere University
tutkimukseen liittyvä kuvaThe study focused on intercellular communication in the retinal pigment epithelial tissue (RPE). (A) Retinal pigment epithelium antibody staining of gap junctions (yellow) and tight junctions (purple) between the cells from a mouse eye. Image size 135x135 µm. (B) Communication between gap junctions was investigated by simultaneously measuring antibody staining in two adjacent cells using tiny microelectrodes. Image size 33x65µm. Photo: Julia Fadyukov
Vision is based on the continuous and precisely regulated interaction between dozens of cell types present in the eye. A recent study investigated the function and intercellular communication of the retinal pigment epithelial tissue which is responsible for the wellness of the retina. The study found that the electrical properties of epithelial cells can be regulated by gap junctions very rapidly. Gap junction halves, or hemichannels, were also found on the surface of the cells, yet their functions have not yet been resolved.

In the study, Julia Fadjukov, a doctoral researcher at Tampere University, utilised a highly accurate cellular measurement method that opened a new possibility for studying epithelial tissue communication.

“The cells of the retinal pigment epithelium (RPE) are tightly interconnected, and they have a dense network of intracellular channels or gap junctions. While gap junctions can transmit intercellular messages, their role in shaping the electrical properties of these cells has not been characterised in epithelial tissue before,” says Fadjukov, the first author of the study.

The study also suggests that epithelial cells can communicate with retinal sensory cells through surface hemichannels.

“This is very exciting news for researchers because several important functions of the epithelial tissue, such as retinal renewal, require precise regulation in accordance with the circadian rhythm,” Fadjukov continues.

Next, the research team wants to investigate whether the communication via intercellular gap junctions is also regulated during these health-promoting activities of our vision. For example, retinal renewal has been found to be impaired in several eye diseases for which current treatments are highly inadequate.

The study led by Adjunct Professor Soile Nymark was conducted by researchers working at Tampere University and the University of Jyväskylä in Finland and Northwestern University in Chicago, Illinois.

Collaboration with Professor Gregory Schwartz’s research group in the United States began with a researcher exchange enabled by a mobility grant awarded by Tampere University’s Doctoral School. During her visit, Fadjukov used electrophysiological measurement methods to determine the function of epithelial cells differentiated from stem cells and the epithelial cells intact in tissue isolated from mice’s eyes.

The measurements of mouse cells are especially challenging because the dark cells are poorly visible under the microscope and their surface is full of bulging membrane structures known as microvilli. This significantly complicates measurements conducted with small microelectrodes, which in this study had to be performed on two adjacent cells simultaneously. This type of gap junction communication measurements on the epithelial tissue have not been published before.

The study was published in the prestigious Journal of General Physiology.

Julia Fadjukov; Sophia Wienbar; Satu Hakanen; Vesa Aho; Maija Vihinen-Ranta; Teemu O. Ihalainen; Gregory W. Schwartz and Soile Nymark. Gap junctions and connexin hemichannels both contribute to the electrical properties of retinal pigment epithelium. Journal of General Physiology 4 April 2022; 154 (4): e202112916. doi: https://doi.org/10.1085/jgp.202112916

Further information:
University Researcher, Adjunct Professor Soile Nymark, +358 40 849 0009 soile.nymark [at] tuni.fi
Faculty of Medicine and Health Technology