TRIOBP

The TRIOBP gene provides instructions for making a protein called TRIO and F-actin binding protein (Triobp). Within cells, the Triobp protein likely regulates aspects of the cytoskeleton, the structural framework that helps to determine cell shape, size, and movement. The Triobp protein is thought to help control the organization of actin filaments, which are long, thin fibers that make up a significant part of the cytoskeleton . Actin filaments are necessary for several normal cellular functions, such as cell division, cell movement (motility), maintenance of cell shape, transport of proteins and other molecules within cells, and chemical signaling between cells.

There are two versions of Triobp, a short version found in most body tissues, and a long version made only in the brain, the eye, and the inner ear. Because of its presence in the inner ear, especially the snail-shaped structure called the cochlea, researchers are interested in this protein's role in hearing. Triobp probably plays a role in the development and maintenance of stereocilia, which are hairlike projections that line the inner ear. Stereocilia, which are rich in actin, bend in response to sound waves. This bending motion is essential for converting sound waves to nerve impulses, a critical process for normal hearing.

nonsyndromic deafness - caused by mutations in the TRIOBP gene

Researchers have identified at least nine TRIOBP mutations that cause a form of nonsyndromic deafness (hearing loss without related signs and symptoms affecting other parts of the body) called DFNB28. Almost all of these mutations introduce a premature stop signal in the instructions for making the long version of Triobp. As a result, an abnormally small version of this protein is made in the brain and inner ear. The abnormal protein probably cannot interact with the actin filaments within stereocilia, leading to hearing loss.