Are vasoactive neuropeptide autoimmune fatigue-related disorders mediated via G protein-coupled receptors?
Vasoactive neuropeptides such as pituitary adenylate cyclase activating polypeptide (PACAP), calcitonin gene related peptide (CGRP) and vasoactive intestinal peptide (VIP) have been implicated in a number of fatigue-related conditions. Associations of these vasoactive neuropeptides with heat shock proteins (hsps) and cytosine-guanosine dinucleotide (CpG) DNA fragments in autoimmune phenomena have been postulated to interfere with receptor signal activation for adenylate cyclase and other vital cellular processes. However, a specific mechanism for receptor dysfunction has not been explored to date. G protein-coupled receptors (GPCRs) constitute a high proportion of biological receptor mechanisms and serve a wide range of substances including nucleosides, nucleotides, catecholamines, calcium, histamine, serotonin and prostaglandins. They are complex transmembrane hepta-helical serpentine structures with specific binding capabilities resulting in conformational changes that activate cognate cyclic GMP (G proteins). GPCRs adapt to certain stimuli through desensitisation and changes in phosphorylation and are subject to distortions of signalling processes. Hence, these vital signalling structures are susceptible to impairment of function through a range of mechanisms. One of their vital functions is signalling through adenylate cyclase, a vital step in cyclic AMP metabolism. This step involves ATP metabolism and therefore is a crucial mediator of cellular energy pathways. Some GPCRs act to inhibit adenylate cyclase (Gi proteins). Also vasoactive neuropeptides, such as PACAP display a number of receptor isotypes including null variants. Overexpression of Gi proteins and null variant receptors may account for major disruptions of signal transduction and ATP/cAMP metabolism. This paper examines the possible role of GPCR dysfunction in contributing to fatigue-related vasoactive neuropeptide autoimmune disorders which may include chronic fatigue syndrome (CFS), Gulf War syndrome (GWS) and even sudden infant death syndrome (SIDS).
Staines
Donald
D
Gold Coast Public Health Unit, 10-12 Young Street, Southport 4215, Qld., Australia. don_staines@health.qld.gov.au
D000255:Adenosine Triphosphate / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D001327:Autoimmune Diseases / Q000276:immunology*; D015740:Calcitonin Gene-Related Peptide / Q000276:immunology; D000242:Cyclic AMP / Q000378:metabolism; D015673:Fatigue Syndrome, Chronic / Q000276:immunology*; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D008954:Models, Biological; D009414:Nerve Growth Factors / Q000276:immunology; D009479:Neuropeptides / Q000276:immunology*; D018377:Neurotransmitter Agents / Q000276:immunology; D009842:Oligopeptides / Q000737:chemistry; D018923:Persian Gulf Syndrome / Q000276:immunology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013398:Sudden Infant Death / Q000276:immunology; D014660:Vasoactive Intestinal Peptide / Q000276:immunology
C495401:ADCYAP1 protein, human; D009414:Nerve Growth Factors; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009842:Oligopeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D043562:Receptors, G-Protein-Coupled; D014660:Vasoactive Intestinal Peptide; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D015740:Calcitonin Gene-Related Peptide