X-inactivation and the dynamic maintenance of gene silencing

• Published in: Molecular genetics and metabolism Vol. 92; no. 1; pp. 56 - 62
• Main Author: Salstrom, Jennifer L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2007
• Subjects: Chromosomes, Human, X - genetics; Dosage Compensation, Genetic; Epigenetic; Gene Silencing - physiology; Genetic Linkage; Heterochromatin; Histone; Humans; LINE; Methylation; Silencing; Trans; X Chromosome Inactivation - physiology; X-inactivation; Xist; X-inactivation; Heterochromatin; LINE; Epigenetic; Xist; Silencing; Histone; Methylation; Trans
• ISSN: 1096-7192; 1096-7206
• DOI: 10.1016/j.ymgme.2007.05.015

X-inactivation has long been a topic of fascination for educators, researchers, and clinicians alike. From complex patterns of inheritance to phenotypic variation among females with X-linked traits, a myriad of hypothesis and interpretations exist. Once thought to be random yet complete, X-inactivation has proven itself the poster child of the exception rather than the rule. Indeed, patterns of X-inactivation are all too often non-random, and many X-linked genes are capable of escaping X-inactivation. Similarly, X-inactivation is well-known for being stably maintained for life, but some previously inactivated X-linked genes reactivate with increasing age. Moreover, recent papers illustrate that X-inactivation can be challenged in other ways, thereby rendering the stability of X-inactivation compromised. This review describes factors involved in the maintenance of X-inactivation as we know it and discusses these emerging data that suggest a more dynamic model of the maintenance of X-inactivation may be in order.