An image of the human brain.
(photo credit: REUTERS)
A recent discovery by researchers at Tel Aviv University may soon change the way Alzheimer’s disease is diagnosed and treated.
The study, published in the journal Translational Psychiatry, describe a gene that codes for a particular protein that researchers discovered.
The protein then turns off signals that it normally produces.
That process, in turn, blocks the brain from moving brain chemicals in their regular manner, also known as neurotransmission, thereby contributing to Alzheimer’s disease.
As a result of the research, it may one day be possible to diagnose the leading cause of dementia with a simple blood test, and new therapies may follow that will be able to halt its progression.
The gene, called RGS2 (Regulator of Protein Signaling 2), has never before been implicated in Alzheimer’s disease. The researchers reported that lower RGS2 expression in Alzheimer’s disease patient cells increases their sensitivity to toxic effects of amyloid-â.
The study was led by two researchers at TAU ’s Sackler School of Medicine: Dr. David Gurwitz, of the human molecular genetics and biochemistry department; and Prof. Illana Gozes, the Lily and Avraham Gildor Chair for the Investigation of Growth Factors, head of the Elton Laboratory for Molecular Neuroendocrinology and a member of TAU ’s Adams Super Center for Brain Studies and Sagol School of Neuroscience.
“Alzheimer’s researchers have until now zeroed in on two specific pathological hallmarks of the chronic neurodegenerative disease: deposits of misfolded amyloid- â (Aâ) peptide plaques, and phosphorylated tau protein neurofibrillary tangles found in diseased brains,” Gurwitz said. “But recent studies suggest amyloid-â plaques are also a common feature of healthy older brains. This raises questions about the central role of Aâ peptides in Alzheimer’s disease pathology.”
The researchers pinpointed a common suspect – the RGS2 gene – by combining genome-wide gene expression profiling of Alzheimer’s disease blood-derived cell lines, with data-mining of previously published gene expression datasets. They found a reduced expression of RGS2 in Alzheimer’s disease blood-derived cell lines, and then validated the observation by examining datasets derived from blood samples and postmortem brain tissue samples from Alzheimer’s disease patients.
“Several genes and their protein products are already known to be implicated in Alzheimer’s disease pathology, but RGS2 has never been studied in this context,” Gurwitz said. “We now propose that whether or not Aâ is a primary culprit in Alzheimer’s disease, neuroprotective mechanisms activated during early disease phases lead to reduced RGS2 expression.”
The TAU study also proposes that reduced RGS2 expression increases the susceptibility of brain neurons to the potentially damaging effects of Aâ. “We found that reduced expression of RGS2 is already noticeable in blood cells during mild cognitive impairment, the earliest phase of Alzheimer’s,” Gurwitz said. “This supported our theory that the reduced RGS2 expression represents a ‘protective mechanism’ triggered by ongoing brain neurodegeneration.”
“Our new observations must now be corroborated by other research groups,” Gurwitz concluded. “The next step will be to design early blood diagnostics and novel therapeutics to offset the negative effects of reduced expression of the RGS2 protein in the brain.”