Researchers from the Max Delbrück Center for Molecular Medicine (MDC) in Berlin-Buch have discovered that a gene, known to control lens development in mice and humans, is also vital for the development of neurons responsible for mechanosensory function. The neurobiologists discovered that mice, whose c-MAF gene had been removed from the nerve cells, experienced an impaired sensation of touch, and that this is similar in human carriers of a mutant c-MAF gene.

Young individuals with such a mutation can already suffer from cataracts, which is a clouding of the lens that commonly affects older people.

Professor Carmen Birchmeier and Dr. Hagen Wende together with Professor Gary Lewin and Dr. Stefan Lechner demonstrated that this mutation causes patients’ to experience difficulties in holding objects, for instance, a sheet of paper.

Professor Birchmeier explained:

“c-Maf is an important gene for the development of the
peripheral nerve cells.”

The development of the neurons that detect touch, called mechanosensory neurons, are controlled by the c-Maf gene, which was previously known as a major regulator of lens development.

The gene also plays a role in the dorsal root ganglia, a collection of nerve cells located next to the spinal cord, where the cell bodies of mechanosensory neurons are located. The nerve cells form long axons, a special cellular extension that arises from the cell body, which terminates in the skin’s touch corpuscles or hair shafts. These axons detect mechanical stimuli, which are subsequently transformed into electrical signals and transmitted to the brain.

For instance, when a person’s fingers stroke over a surface, the surface structure triggers high-frequency vibrations in the finger, which evoke a response by specific touch receptors, such as the Pacinian corpuscles.

Mice with a deactivated c-Maf gene only formed a few Pacinian corpuscles, which also happened to be impaired. This means mice are unable to recognize high-frequency vibrations, and the same applies for a Swiss family with an inherited mutant c-Maf gene. As a result, the affected patients develop cataracts at an early age and have an impaired sense of touch.

Written by Petra Rattue