image: Cockayne syndrome B (CSB) protein is known to be abundant in the nucleus where it participates in DNA repair. However, a fraction of CSB is located at the centrosome, the microtubule-organizing center of the cell, where it colocalizes with the alpha-tubulin acetyltransferase MEC-17 and the histone deacetylase HDAC6. The functional interplay between these proteins appears to be important for induction of acetyl-alpha-tubulin, a post-translational modification required for promoting the stress-protective mechanism autophagy. In the skin, CSB-induced autophagy protects integrity of the subcutaneous fat. Absence of a functional CSB protein in Cockayne syndrome leading to dysfunction of alpha-tubulin acetylation and autophagy as well as degeneration of subcutaneous fat in the skin of CSB-deficient mice can be prevented by administration of the pan-HDAC inhibitor SAHA indicating that CSB-mediated protein acetylation is critical for maintaining integrity of subcutaneous fat. view more
Credit: IUF Leibniz Research Institute for Environmental Medicine
Duesseldorf, 29/08/2018. The Cockayne syndrome is a very rare hereditary disease, which can lead among others to dwarfism, neurological impairment, premature aging and a shortened life span. Skin symptoms include a striking sensitivity to UV rays and a dramatic loss of subcutaneous fat. The disease is caused in 80 % of the cases by a mutation in the CSB gene. There is no curative treatment. The CSB protein is well known for its role in DNA repair and the Cockayne syndrome therefore usually described as a DNA repair deficiency syndrome. This view, however, does not explain the diverse clinical phenotype of the patients and hence, the CSB protein most likely serves important biological functions beyond DNA repair.
A study of the IUF - Leibniz Research Institute for Environmental Medicine and the Heinrich Heine University Duesseldorf (HHU), Germany, now shows for the first time that the CSB protein is not only present in the nucleus but also at the centrosome of the cell where it enhances acetylation (a certain modification) of alpha-Tubulin (a protein which forms routes of transportation in the cell) and thereby regulates autophagy (the degradation of cellular material in the cell fluid). If the protein is not able to fulfill this task, an imbalance in protein acetylation occurs. Administration of the histone deacetylase inhibitor SAHA, which inhibits a certain protein family in reversing acetylation, was able to restore this balance. Of note, the loss of subcutaneous fat, i.e. a hallmark of Cockayne syndrome B, could also be restored by SAHA in the mouse model. These results, which have been generated across several species including nematodes, mice and human skin cells, were now published in "Science Translational Medicine". Future studies will assess if the HDAC inhibitor SAHA, which is a FDA approved drug for treating certain forms of cutaneous T cell lymphoma, is also suitable for the treatment of patients with Cockayne syndrome.
"More and more biological functions beyond DNA repair are being discovered for proteins, which were originally described as DNA repair enzymes. Examples are the CSB protein but also the XPA protein which causes a very severe subtype of Xeroderma pigmentosum", says Prof. Jean Krutmann, director of the IUF. "This paradigm shift might allow us to identify new strategies for the treatment of these incurable diseases".
The investigations with the nematodes were conducted by a liaison group between the IUF and the Central Institute of Clinical Chemistry and Laboratory Medicine of the Heinrich Heine University in Duesseldorf, Germany, which is led by Dr. Natascia Ventura.
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Source
Majora M, Sondenheimer K, Knechten M, Uthe I, Esser C, Schiavi A, Ventura N, Krutmann J: HDAC inhibition improves autophagic and lysosomal function to prevent loss of subcutaneous fat in a mouse model of Cockayne syndrome. Sci Transl Med 2018.
More information, including a copy of the paper, can be found online at the Science Translational Medicine press package at http://www.eurekalert.org/jrnls/scitransmed. You will need your user ID and password to access this information.
About the IUF
The IUF - Leibniz Research Institute for Environmental Medicine investigates the molecular mechanisms through which particles, radiation and environmental chemicals harm human health. The main working areas are environmentally induced aging of the cardiopulmonary system and the skin as well as disturbances of the nervous and immune system. Through development of novel model systems the IUF contributes to the improvement of risk assessment and the identification of novel strategies for the prevention / therapy of environmentally induced health damage.
More information: http://www.iuf-duesseldorf.com.
The IUF is part of the Leibniz Association: http://www.leibniz-gemeinschaft.de/en/home.
Journal
Science Translational Medicine