Page last updated: 2024-10-24

random inactivation of X chromosome

Definition

Target type: biologicalprocess

Compensating for the two-fold variation in X-chromosome:autosome ratios between sexes by a global inactivation of all, or most of, the genes on either the paternal or maternal X-chromosome in the XX sex. [GOC:dph, GOC:sdb_2009, GOC:tb, PMID:32189388]

Random inactivation of the X chromosome, also known as X-inactivation, is a process that occurs in female mammals to compensate for the dosage difference between males (XY) and females (XX) in terms of X-linked genes. This intricate mechanism ensures that females do not express twice the amount of X-linked gene products compared to males.

The process begins early in embryonic development, typically around the 16-cell stage. One of the two X chromosomes in each cell is randomly chosen to be inactivated, becoming highly condensed and forming a structure called a Barr body. This inactive X chromosome is largely silenced, meaning its genes are not transcribed into RNA.

The selection of which X chromosome to inactivate is random and independent in each cell. This means that different cells in a female’s body can have different X chromosomes inactivated, leading to a mosaic pattern of X chromosome expression.

The inactivation process is initiated by a non-coding RNA called XIST (X-inactive specific transcript). XIST is transcribed from the X chromosome that will be inactivated and coats that chromosome, silencing its genes.

The X chromosome inactivation process is a complex and tightly regulated process involving several key factors. It is essential for proper development in female mammals and helps to ensure equal expression of X-linked genes between males and females.

X inactivation has important implications for human health. It explains why females who carry a mutated X chromosome may not exhibit the same severity of disease as males with the same mutation. However, the random nature of X inactivation can also lead to variations in disease expression among females, depending on which X chromosome is inactivated in different cells.'
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Proteins (2)

ProteinDefinitionTaxonomy
Polycomb protein SUZ12A polycomb protein SUZ12 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q15022]Homo sapiens (human)
Breast cancer type 1 susceptibility proteinA breast cancer type 1 susceptibility protein that is encoded in the genome of human. [PRO:DNx]Homo sapiens (human)

Compounds (7)

CompoundDefinitionClassesRoles
beta-thujaplicinbeta-thujaplicin : A monoterpenoid that is cyclohepta-2,4,6-trien-1-one substituted by a hydroxy group at position 2 and an isopropyl group at position 4. Isolated from Thuja plicata and Chamaecyparis obtusa, it exhibits antimicrobial activities.

beta-thujaplicin: structure
cyclic ketone;
enol;
monoterpenoid
antibacterial agent;
antifungal agent;
antineoplastic agent;
antiplasmodial drug;
plant metabolite
tanshinonetanshinone: from root of Salvia miltiorrhiza Bunge; RN given refers to tanshinone I; cardioprotective agent and neuroprotective agentabietane diterpenoidanticoronaviral agent
przewaquinone dprzewaquinone D: isolated from root of Salvia przewalskii; structure given in first source; RN given refers to the trans- isomer, przewaquinone D
tanshinone ii atashinone IIA: a cardiovascular agent with antineoplastic activity; isolated from Salvia miltiorrhiza; structure in first sourceabietane diterpenoid
epz-6438tazemetostat: a histone methyltransferase EZH2 inhibitor with antineoplastic activity
gsk-2816126GSK-2816126: inhibits EZH2 methyltransferase; structure in first sourcepiperazines;
pyridines
gsk343GSK343 : A member of the class of indazoles that is 1-isopropyl-1H-indazole-4-carboxamide in which the nitrogen of the carboxamide group is substituted by a (6-methyl-2-oxo-4-propyl-1,2-dihydropyridin-3-yl)methyl group and in which the indazole ring is substituted at position 6 by a 2-(4-methylpiperazin-1-yl)pyridin-4-yl group. A highly potent and selective EZH2 inhibitor (IC50 = 4 nM).

GSK343: an EZH2 methyltransferase inhibitor
aminopyridine;
indazoles;
N-alkylpiperazine;
N-arylpiperazine;
pyridone;
secondary carboxamide
antineoplastic agent;
apoptosis inducer;
EC 2.1.1.43 (enhancer of zeste homolog 2) inhibitor