Abstract
In the field of neurodegenerative disease, the so-called polyglutamine diseases hold a unique place. These nine different diseases, which include Huntington disease and several forms of spinocerebellar ataxia, involve nine different genes. But each gene carries the same mutation—an increase in the number of CAG nucleotide triplets. In the normal genes, the number of CAG units is 30 or less; in the mutated form, this grows to 35 or more. CAG codes for the amino acid glutamine, and the consequence of each mutation is to create an expanded polyglutamine tract within the protein encoded by the gene. The presence of this tract kills nerve cells, by a mechanism or mechanisms that still remain unclear.
Highlights
Because uncontrolled cell division is so dangerous for an organism, the well-behaved cell must know when to divide, and—crucially—when not to
A cell in such a temporary, nondividing state is said to be “quiescent.” Signals that send a cell into quiescence include loss of contact with the underlying surface, too much contact with neighboring cells, and not receiving specific growth factors from the surroundings
The reversibility of quiescence contrasts with the cell cycle arrest induced by inhibition of cyclin-dependent kinase (CDK), a key regulatory protein
Summary
Because uncontrolled cell division is so dangerous for an organism, the well-behaved cell must know when to divide, and—crucially—when not to. After 20 days, there were over 100 genes whose change in expression linked them to quiescence These included those that regulate metabolism and cell division, as might be expected, and genes that suppress the transition to two other cell fates— differentiation and programmed death. The expression of these genes (along with many others) was increased, indicating the active nature of the quiescent state. The identification of different quiescent states, induced by the three different signals, may lead to a better understanding of context-specific control of cell growth during development and repair, in muscle, but perhaps in other tissues as well.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
