Species Human Entrez 545 | Human Mouse Ensembl ENSG00000175054 | |
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Aliases ATR, ATR serine/threonine kinase, FCTCS, FRP1, MEC1, SCKL, SCKL1 External IDs MGI: 108028 HomoloGene: 96916 GeneCards: ATR | ||
Serine/threonine-protein kinase ATR also known as ataxia telangiectasia and Rad3-related protein (ATR) or FRAP-related protein 1 (FRP1) is an enzyme that, in humans, is encoded by the ATR gene. ATR belongs to the phosphatidylinositol 3-kinase-related kinase protein family.
Contents
Function
ATR is a serine/threonine-specific protein kinase that is involved in sensing DNA damage and activating the DNA damage checkpoint, leading to cell cycle arrest. ATR is activated in response to persistent single-stranded DNA, which is a common intermediate formed during DNA damage detection and repair. Single-stranded DNA occurs at stalled replication forks and as an intermediate in DNA repair pathways such as nucleotide excision repair and homologous recombination repair. ATR works with a partner protein called ATRIP to recognize single-stranded DNA coated with RPA. Once ATR is activated, it phosphorylates Chk1, initiating a signal transduction cascade that culminates in cell cycle arrest. In addition to its role in activating the DNA damage checkpoint, ATR is thought to function in unperturbed DNA replication.
ATR is related to a second checkpoint-activating kinase, ATM, which is activated by double strand breaks in DNA or chromatin disruption.
Clinical significance
Mutations in ATR are responsible for Seckel syndrome, a rare human disorder that shares some characteristics with ataxia telangiectasia, which results from ATM mutation.
ATR/ChK1 inhibitors can potentiate the effect of DNA cross-linking agents. The first clinical trials using inhibitors of ATR have been initiated by AstraZeneca, preferably in ATM-mutated chronic lymphocytic leukaemia (CLL), prolymphocytic leukaemia (PLL) or B-cell lymphoma patients and by Vertex Pharmaceuticals in advanced solid tumours.
Aging
Deficiency of ATR expression in adult mice leads to the appearance of age-related alterations such as hair graying, hair loss, kyphosis (rounded upper back), osteoporosis and thymic involution. Furthermore there are dramatic reductions with age in tissue-specific stem and progenitor cells, and exhaustion of tissue renewal and homeostatic capacity. There was also an early and permanent loss of spermatogenesis. However there was no significant increase in tumor risk.
Seckel syndrome
In humans, hypomorphic mutations (partial loss of gene function) in the ATR gene are linked to Seckel syndrome, a condition characterized by proportionate dwarfism, developmental delay, marked microcephaly, dental malocclusion and thoracic kyphosis. A senile or progeroid appearance has also been frequently noted in Seckel patients.
Homologous recombinational repair
Somatic cells of mice deficient in ATR have a decreased frequency of homologous recombination and an increased level of chromosomal damage. This finding implies that ATR is required for homologous recombinational repair of endogenous DNA damage.
Drosophila mitosis and meiosis
Mei-41 is the Drosophila ortholog of ATR. During mitosis in Drosophila DNA damages caused by exogenous agents are repaired by an homologous recombination process that depends on mei-41(ATR). Mutants defective in mei-41(ATR) have increased sensitivity to killing by exposure to the DNA damaging agents UV , and methyl methanesulfonate. Deficiency of mei-41(ATR) also causes reduced spontaneous allelic recombination (crossing over) during meiosis suggesting that wild-type mei-41(ATR) is employed in recombinational repair of spontaneous DNA damages during meiosis.
Interactions
Ataxia telangiectasia and Rad3 related has been shown to interact with: