Activating the ERK pathway (extracellular signal‐regulated kinase pathway) has proven beneficial in several models of Huntington's disease (HD), and drugs that are protective in HD models have recently been found to activate ERK. Thus, the ERK cascade may be a potential target for therapeutic intervention in this currently untreatable disorder. HD is caused by an expanded polyglutamine repeat in the huntingtin (Htt) protein that actuates a diverse set of pathogenic mechanisms. In response to mutant Htt, ERK is activated and directs (...) a protective transcriptional response and inhibits caspase activation. Paradoxically, Htt also interferes with several signaling events of the ERK pathway. Mutant Htt compromises the ERK‐dependent transcriptional response to corticostriatal BDNF signaling. Mutant Htt also hinders glutamate uptake from the synaptic cleft by down‐regulating ERK‐dependent expression of glutamate transporters, leaving cells vulnerable to excitotoxicity. Some of this cellular complexity can be capitalized on to achieve selective activation of ERK, which can be protective. (shrink)

Neurodegenerative diseases are becoming increasingly common as life expectancy increases. Recent years have seen tremendous progress in the identification of genes that cause these diseases. While mutations have been found and cellular processes defined that are altered in the disease state, the identification of treatments and cures has proven more elusive. The process of finding drugs and therapies to treat human diseases can be slow, expensive and frustrating. Can model organisms such as Drosophila speed the process of finding cures and (...) treatments for human neurodegenerative diseases? We pose three questions, (1) can one mimic the essential features of human diseases in an organism like Drosophila, (2) can one cure a model organisms of human disease and (3) will these efforts accelerate the identification of useful therapies for testing in mice and ultimately humans? Here we focus on the use of Drosophila to identify potential treatments for neurodegenerative diseases such as Huntington's and we discuss how well these therapies translate into mammalian systems. BioEssays 26:485–496, 2004. © 2004 Wiley Periodicals, Inc. (shrink)