Biologists first created a map of the work of genes in the retina of a primate. This is important for combating eye diseases, since only primates have a central fossa on the retina, thanks to which we distinguish colors and subtle details of objects.
The achievement is described in a scientific article published in Cell magazine by a group led by Joshua Sanes of Harvard University.
A classic biomedical research object is a laboratory mouse. However, as mentioned above, mice do not have a central fossa, this most important detail of the human eye, the damage of which can be associated with numerous diseases leading to blindness.
The anatomy of the central fossa is well studied. However, for the first time, scientists have determined in which cells of which genes it works (expressed).
Recall that the gene is an instruction for the synthesis of RNA, and RNA is an instruction for the synthesis of protein. All cells of the body contain the same DNA, but they differ in what genes in one or another cell RNA is actually synthesized (and through it proteins), and which “are silent.” Proteins determine almost all cell activity.
To map the working genes, the authors examined 165 thousand cells of the macaque eye and sequenced the RNA of each of them. Half of the cells were taken from the central fossa, and the rest from the periphery of the retina. Both neurons and the “bricks” of other tissues were analyzed.
Biologists have identified more than 60 types of cells that differ in anatomical details. More than 80% of these types were found both in the central fossa and in the periphery. However, there are important differences between these two regions. The difference was, firstly, in how often cells of one or another type met, and secondly, in the same gene expression.
Armed with these results, biologists have verified where about 200 genes work, whose activity in humans is associated with the development of blindness. It turned out that some of them are selectively expressed in the central fossa. This is especially true of genes responsible for susceptibility to macular degeneration and macular edema, and these are one of the most common causes of blindness.
“For example, we found that one susceptibility gene for macular degeneration in rods and cones of the central fossa is expressed at a much higher level than in peripheral rods and cones,” Sanes says. “Similarly, we found two susceptibility genes for diabetic macular edema, expressed in the blood vessels of the central fossa more intensely than at the periphery. ”
By comparing their data with the gene expression atlas in the mouse retina, known from the work of the precursors, biologists found that these genes either do not work at all in rodents or are included in other places of the retina than in primates. That is why the data obtained can be invaluable help in the fight against human diseases.