By PLoS, [RxPG] To function, each living cell needs both to build new and to degrade old or damaged proteins. To accomplish that, a number of intracellular systems work in concert to keep the cell healthy and from clogging up with damaged proteins. When proteins or peptides mutate, they can present major problems
to the clearing up of the intracellular environment. In Huntington¡¦s disease (HD) the disease provoking mutation in the huntingtin gene eventually causes the cell to build up intranuclear and cellular inclusions of protein-aggregates, made up primarily of huntingtin. One cellular organelle with a central role of clearing such protein build up in the cell is the ubiquitin proteasome system (UPS).
In Huntington¡¦s disease (HD) brains and other tissues, UPS activity is inhibited and intraneuronal nuclear protein aggregates of mutant huntingtin in HD brains indicate dysfunction of the UPS. From these results, the researchers hypothesized that enhancing UPS function would improve catalytic degradation of abnormal proteins in HD. They first genetically engineered proteasome activators involved in either non-ubiquitinated protein degradation pathways(PA28×) or subunits of PA700, the 26S proteasome ubiquitinated pathway (S5a) into transducible lentiviral vectors. To address the therapeutic hypothesis experimentally, the researchers transduced UPS subunits into HD skin fibroblasts or HD mutant protein expressing striatum-derived neurons. They determined how this intervention altered cell survival after exposure to toxins known to simulate pathological mechanisms in HD.
The manuscript shows that cellular changes due to expression of huntingtin protein with longer CAG repeats can reduce the ubiquitin proteasome system (UPS) function in Huntington¡¦s disease cells. Following compromise of the UPS, the overexpression of proteasome activator PA28×n can specifically recover proteasome function and improve cell viability in both HD model and patient cells.
These remarkable results demonstrate for the first time that it is possible to intervene therapeutically in the proteolytic pathways and organelles that participate in the specific degradation of misfolded and abnormal proteins.
Funding information and declaration of competing interests:This work was primarily supported by NIH, the Vaughan Foundation and in part by a KRF Grant funded by the Korean Government, Hanyang University and BK21 fellowship.
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About Dr. Sanjukta Acharya
This news story has been reviewed by Dr. Sanjukta Acharya before its publication on RxPG News website. Dr. Sanjukta Acharya, MBBS is the chief editor for RxPG News website. She oversees all the medical news submissions and manages the medicine section of the website. She has a special interest in diabetes and endocrinology.
RxPG News is committed to promotion and implementation of Evidence Based Medical Journalism in all channels of mass media including internet.
Additional information about the news article
The researchers were Hyemyung Seo, Kai-Christian Sonntag1, Woori Kim, Elena Cattaneo and Ole Isacson
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