Regulation of RNA degradation pathways during the lipopolysaccharide response in Macrophages.

The innate immune response to LPS is highly dynamic yet tightly regulated. The majority of studies of gene expression have focussed on transcription. However, it is also important to understand how post-transcriptional pathways are regulated in response to inflammatory stimuli as the rate of RNA degradation relative to new transcription is important for overall expression.

SMG1 heterozygosity exacerbates haematopoietic cancer development in Atm null mice by increasing persistent DNA damage and oxidative stress.

Suppressor of morphogenesis in genitalia 1 (SMG1) and ataxia telangiectasia mutated (ATM) are members of the PI3-kinase like-kinase (PIKK) family of proteins. ATM is a well-established tumour suppressor. Loss of one or both alleles of ATM results in an increased risk of cancer development, particularly haematopoietic cancer and breast cancer in both humans and mouse models.

A rat model of ataxia-telangiectasia: evidence for a neurodegenerative phenotype.

Ataxia-telangiectasia (A-T), an autosomal recessive disease caused by mutations in the ATM gene is characterised by cerebellar atrophy and progressive neurodegeneration which has been poorly recapitulated in Atm mutant mice. Consequently, pathways leading to neurodegeneration in A-T are poorly understood. We describe here the generation of an Atm knockout rat model that does not display cerebellar atrophy but instead paralysis and spinal cord atrophy, reminiscent of that seen in older patients and milder forms of the disorder.

Rats with a missense mutation in Atm display neuroinflammation and neurodegeneration subsequent to accumulation of cytosolic DNA following unrepaired DNA damage.

Mutations in the ataxia-telangiectasia (A-T)-mutated () gene give rise to the human genetic disorder A-T, characterized by immunodeficiency, cancer predisposition, and neurodegeneration. Whereas a series of animal models recapitulate much of the A-T phenotype, they fail to present with ataxia or neurodegeneration. We describe here the generation of an missense mutant [amino acid change of leucine (L) to proline (P) at position 2262 (L2262P)] rat by intracytoplasmic injection (ICSI) of mutant sperm into oocytes.

Senataxin controls meiotic silencing through ATR activation and chromatin remodeling.

Senataxin, defective in ataxia oculomotor apraxia type 2, protects the genome by facilitating the resolution of RNA-DNA hybrids (R-loops) and other aspects of RNA processing. Disruption of this gene in mice causes failure of meiotic recombination and defective meiotic sex chromosome inactivation, leading to male infertility. Here we provide evidence that the disruption of Setx leads to reduced SUMOylation and disruption of protein localization across the XY body during meiosis.

R-loops in proliferating cells but not in the brain: implications for AOA2 and other autosomal recessive ataxias.

Disruption of the Setx gene, defective in ataxia oculomotor apraxia type 2 (AOA2) leads to the accumulation of DNA/RNA hybrids (R-loops), failure of meiotic recombination and infertility in mice. We report here the presence of R-loops in the testes from other autosomal recessive ataxia mouse models, which correlate with fertility in these disorders. R-loops were coincident in cells showing high basal levels of DNA double strand breaks and in those cells undergoing apoptosis.

Senataxin plays an essential role with DNA damage response proteins in meiotic recombination and gene silencing.

Senataxin, mutated in the human genetic disorder ataxia with oculomotor apraxia type 2 (AOA2), plays an important role in maintaining genome integrity by coordination of transcription, DNA replication, and the DNA damage response. We demonstrate that senataxin is essential for spermatogenesis and that it functions at two stages in meiosis during crossing-over in homologous recombination and in meiotic sex chromosome inactivation (MSCI). Disruption of the Setx gene caused persistence of DNA double-strand breaks, a defect in disassembly of Rad51 filaments, accumulation of DNA:RNA hybrids (R-loops), and ultimately a failure of crossing-over.

Myeloma-induced alloreactive T cells arising in myeloma-infiltrated bones include double-positive CD8+CD4+ T cells: evidence from myeloma-bearing mouse model.

The graft-versus-myeloma (GVM) effect represents a powerful form of immune attack exerted by alloreactive T cells against multiple myeloma cells, which leads to clinical responses in multiple myeloma transplant recipients. Whether myeloma cells are themselves able to induce alloreactive T cells capable of the GVM effect is not defined. Using adoptive transfer of T naive cells into myeloma-bearing mice (established by transplantation of human RPMI8226-TGL myeloma cells into CD122(+) cell-depleted NOD/SCID hosts), we found that myeloma cells induced alloreactive T cells that suppressed myeloma growth and prolonged survival of T cell recipients.

Dramatic extension of tumor latency and correction of neurobehavioral phenotype in Atm-mutant mice with a nitroxide antioxidant.

Mutations in the ATM gene (mutated in ataxia telangiectasia) in both humans and mice predispose to lymphoid tumors. A defect in this gene also causes neurodegeneration in humans and a less severe neurological phenotype in mice. There is some evidence that oxidative stress contributes to these defects, suggesting that antioxidants could alleviate the phenotype.

Regulation of the Atm promoter in vivo.

While ATM, the protein defective in the human genetic disorder ataxia-telangiectasia (A-T), is primarily activated as a preexisting protein by radiation, there is also evidence that expression of the protein can be regulated at the transcriptional level. Activation of the ATM promoter by ionizing radiation has been reported only in quiescent cells in culture. To investigate how the Atm promoter is regulated in vivo, we generated transgenic mice that express the luciferase reporter gene under the control of the murine Atm promoter.

Oxidative stress is responsible for deficient survival and dendritogenesis in purkinje neurons from ataxia-telangiectasia mutated mutant mice.

Atm gene-disrupted mice recapitulate the majority of characteristics observed in patients with the genetic disorder ataxia-telangiectasia (A-T). However, although they exhibit defects in neuromotor function and a distinct neurological phenotype, they do not show the progressive neurodegeneration seen in human patients, but there is evidence that ataxia-telangiectasia mutated (Atm)-deficient animals have elevated levels of oxidized macromolecules and some neuropathology. We report here that in vitro survival of cerebellar Purkinje cells from both Atm "knock-out" and Atm "knock-in" mice was significantly reduced compared with their wild-type littermates.