Researchers at Oregon State University have been working on what could lead to the development of gene therapies for those born deaf. Mutations in a protein called otoferlin, which binds to calcium receptors in the sensory hair cells of the inner ear, can be directly linked to hearing loss.
The team found more than 60 mutations that weaken this bond to the sensory hair cells of the ear, marking the first of many steps to identifying successful therapies.
In a press release from OSU, Colin Johnson, associate professor of biochemistry and biophysics stated that, “a lot of genes will find various things to do, but otoferlin seems only to have one purpose, and that is to encode sound in the sensory hair cells in the inner ear. And small mutations in otoferlin render people profoundly deaf.”
The size of the protein has been causing problems for researchers thus far.
“The otoferlin gene is really big, and it makes a huge protein,” Johnson explains, “the traditional method for making a recombinant protein is using E. coli, but they loathe big proteins. This paper came up with a way of getting around that challenge.”
“We were trying to shorten the gene, to find a truncated form that can be used for gene therapy,” Johnson added.
“There is a size limit in terms of what you can package into the gene delivery vehicle, and otoferlin is too large. That’s the holy grail; trying to find a miniature version of otoferlin that can be packaged into the delivery vehicle, and then hopefully, the patient can start hearing.”
To get around these obstacles and find out how otoferlin mutations affected their bond to calcium receptors, the researchers developed a new way to assess that bond after identifying a truncated form of the protein that can function in the encoding of sound.
This research not only opens a door for people who are born with hearing loss, but for researchers working to solve similar problems through bioscience as well.
Johnson’s team included doctoral biochemistry student Nicole Hams, former biochemistry doctoral student Murugesh Padmanarayana, and assistant professor of biophysics Weihong Qiu.
By Andy Hahn