X chromosome reactivation perturbs intracellular self/not-self discrimination.
New reports indicate a chromosomal rather than hormonal basis for the susceptibility of females to autoimmune disease. It is held that if females reactivate an inactivated X chromosome, there will be overexpression of certain X-located genes affecting immune function. Hence, normal mechanisms of self/not-self discrimination might be impaired resulting in immune reaction to self antigens. However, the data are also consistent with the long-held view that the demands of intracellular self/not-self discrimination have driven the evolution of X-chromosome dosage compensation. It was proposed that, whether cells are in male or female bodies, concentrations of proteins are fine-tuned up to their aggregation thresholds. A disruption of this equilibrium, by agents originating either externally (for example, virus) or internally (for example, reactivated X chromosome), generates homoaggregates that trigger responses against the respective not-self or self antigens. Thus, female susceptibility to autoimmune disease may not be because certain immune system genes happen to be X-located, but because self/not-self discrimination was the raison d'être for X-chromosome dosage compensation in the first place.
Forsdyke
Donald R
DR
Department of Biochemistry, Queen's University, Ontario, Canada. forsdyke@queensu.ca
D001324:Autoantigens / Q000276:immunology / Q000378:metabolism; D015551:Autoimmunity / Q000235:genetics; D041321:Chromosomes, Human, X / Q000235:genetics* / Q000378:metabolism; D004303:Dosage Compensation, Genetic / Q000276:immunology* / Q000502:physiology; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000235:genetics / Q000276:immunology; D012330:RNA, Double-Stranded / Q000276:immunology / Q000378:metabolism; D017634:Self Tolerance / Q000235:genetics*
D001324:Autoantigens; D012330:RNA, Double-Stranded