Gene Regulator May Contribute to Protein Pileup in Exfoliation Glaucoma

In exfoliation glaucoma, a protein dandruff clogs the outflow pathway for the fluid in our eyes.

A recent study shows that variants of the same gene that enables us to make connective tissue by crosslinking proteins is associated with this unusual glaucoma.

Scientists have been examining RNA in human eye tissue, that helps control LOXL1 gene expression, with the idea that it may be a culprit in the destructive pileup of LOXL1 protein inside the eye.

A new $440,000 grant from the National Eye Institute is helping Dr. Yutao Liu and his colleagues further explore the relationship between the gene and this long, noncoding RNA dubbed “lncLOXL1”.

The team aims to find treatment targets for this glaucoma, which is generally more aggressive and difficult to treat than primary open angle glaucoma, its more common counterpart. Geneticist Liu from the Department of Cellular Biology and Anatomy at the Medical College of Georgia at Augusta University expands:

“Variants of this gene are associated with the disease in every population we have studied worldwide.”

They established that the expression of LOXL1 was consistently elevated early in the process of glaucoma development in every population.

High levels of LOXL1 protein that clog outflow tracts for the eye’s aqueous humor also are a constant in all those patients. Still, there is conflicting evidence about the role of the suspect gene because removing or overexpressing it doesn’t always result in protein accumulation and high pressure inside the eye, at least in animals.

So far, they have established that the expression level of the gene and lncLOXL1 correlate in both gene variations the scientists have seen in the human populations they have studied. They also have seen that as disease progresses, the gene expression goes down even as the protein piles up, typically at about age 60.

One of the many things they want to know now is what happens to the lncLOXL1 expression in disease. Does its expression also go down when disease becomes symptomatic, or does its parallel expression with the gene part ways at that point?

Knowing that will help determine whether it might one day need to be turned up or down to help patients, Liu says.

They also are further refining exactly what lncLOXL1 does and how it does it by looking at what genes/proteins are affected when it’s knocked out and overexpressed.

“We are looking at what happens to expression of both the LOXL1 gene and its protein when we remove lncLOXL1 from the equation and when we overexpress it,” Liu says.

The team are also investigating other inflammatory factors which may contribute to glaucoma.

This article has been republished from materials provided by Augusta University. Note: material may have been edited for length and content. For further information, please contact the cited source.

Reference:
Drewry, M. D., Challa, P., Kuchtey, J. G., Navarro, I., Helwa, I., Hu, Y., . . . Liu, Y. (2018). Differentially expressed microRNAs in the aqueous humor of patients with exfoliation glaucoma or primary open-angle glaucoma. Human Molecular Genetics, 27(7), 1263-1275. doi:10.1093/hmg/ddy040