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TheScientificWorldJOURNAL
Volume 10 (2010), Pages 1667-1678
http://dx.doi.org/10.1100/tsw.2010.154
Mini-Review Article

Dysfunction of G Protein-Coupled Receptor Kinases in Alzheimer’'s Disease

1Laboratory for Alzheimer's Disease and Aging Research, VA Medical Center, Kansas City, MO, USA
2Department of Neurology, University of Kansas Medical Center, Kansas City, KS, USA
3Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA

Received 21 January 2010; Revised 29 June 2010; Accepted 6 July 2010

Academic Editor: Rudy Tanzi

Copyright © 2010 William Z. Suo and Longxuan Li.

Abstract

Although mutations and variations of several genes have been identified to be involved in Alzheimer's disease (AD), the efforts towards understanding the pathogenic mechanisms of the disease still have a long journey to go. One such effort is to identify the signal transduction deficits, for which previous studies have suggested that the central problems appear to be at the interface between G proteins and their coupled receptors. G protein-coupled receptor kinases (GRKs) are a small family of serine/threonine protein kinases primarily acting at the “receptor-G protein interface””. Recent studies have indicated the possible involvement of GRK, primarily GRK2 and GRK5, dysfunction in the pathogenesis of AD. It seems that mild, soluble, β-amyloid accumulation can lead to a reduced membrane (functional) and an elevated cytosolic GRK2/5. The increased cytosolic GRK2 appears to be colocalized with damaged mitochondria and neurofibrillary tangles. Moreover, the total levels of GRK2, not only in the brain, but also in peripheral blood samples, are increased in a manner inversely correlated with the patient's cognitive levels. The deficiency of GRK5, on the other hand, impairs presynaptic M2 autoreceptor desensitization, which leads to a reduced acetylcholine release, axonal/synaptic degenerative changes, and associated amnestic, mild cognitive impairment. It also promotes an evil cycle to further increase Beta-amyloid accumulation and exaggerates brain inflammation, possibly even the basal forebrain cholinergic degeneration. Therefore, continuous efforts in this direction are necessary before translating the knowledge to any therapeutic strategies.