Recurring mutations found by sequencing an acute myeloid leukemia genome.

Background: The full complement of DNA mutations that are responsible for the pathogenesis of acute myeloid leukemia (AML) is not yet known.

Methods: We used massively parallel DNA sequencing to obtain a very high level of coverage (approximately 98%) of a primary, cytogenetically normal, de novo genome for AML with minimal maturation (AML-M1) and a matched normal skin genome.

Results: We identified 12 acquired (somatic) mutations within the coding sequences of genes and 52 somatic point mutations in conserved or regulatory portions of the genome.

Somatic mutations affect key pathways in lung adenocarcinoma.

Determining the genetic basis of cancer requires comprehensive analyses of large collections of histopathologically well-classified primary tumours. Here we report the results of a collaborative study to discover somatic mutations in 188 human lung adenocarcinomas. DNA sequencing of 623 genes with known or potential relationships to cancer revealed more than 1,000 somatic mutations across the samples.

Akt-dependent cell size regulation by the adhesion molecule on glia occurs independently of phosphatidylinositol 3-kinase and Rheb signaling.

The role of cell adhesion molecules in mediating interactions with neighboring cells and the extracellular matrix has long been appreciated. More recently, these molecules have been shown to modulate intracellular signal transduction cascades critical for cell growth and proliferation. Expression of adhesion molecule on glia (AMOG) is downregulated in human and mouse gliomas, suggesting that AMOG may be important for growth regulation in the brain.

Serine 518 phosphorylation modulates merlin intramolecular association and binding to critical effectors important for NF2 growth suppression.

The neurofibromatosis 2 (NF2) tumor suppressor protein, merlin, functions as a negative growth regulator; however, the molecular mechanisms that underlie merlin regulation remain elusive. Recent studies have implicated merlin phosphorylation in regulating merlin subcellular localization and growth suppression. P21-activated kinase (PAK), a downstream target of Rac1/Cdc42, directly phosphorylates merlin at Serine 518.

Functional significance of S6K overexpression in meningioma progression.

One common genetic change in anaplastic meningiomas is amplification of chromosome 17q23 containing the S6 kinase (S6K) gene. We show, for the first time to our knowledge, increased S6K mRNA expression in anaplastic meningiomas compared with benign tumors. To evaluate S6K as a candidate meningioma progression gene, we generated IOMM-Lee human meningioma cell lines overexpressing S6K.

Characterization of chicken Nf2/merlin indicates regulatory roles in cell proliferation and migration.

The neurofibromatosis 2 (NF2) tumor suppressor protein merlin, or schwannomin, functions as a negative growth regulator such that inactivating mutations in Nf2 predispose humans to tumors. In addition, merlin has a critical role during embryonic development. Nf2-deficient mice die early during embryogenesis, with defects in gastrulation and extraembryonic tissues.

Effect of merlin phosphorylation on neurofibromatosis 2 (NF2) gene function.

The neurofibromatosis 2 (NF2) tumor suppressor gene product, merlin, belongs to the ezrin-radixin-moesin (ERM) subgroup of the Protein 4.1 family, which links cell surface glycoproteins to the actin cytoskeleton. Previous studies have suggested that phosphorylation of merlin, similar to other ERM proteins, may regulate its function.

Genetic heterogeneity of stably transfected cell lines revealed by expression profiling with oligonucleotide microarrays.

Large-scale gene expression measurements with oligonucleotide microarrays have contributed tremendously to biological research. However, to distinguish between relevant expression changes and falsely identified positives, the source and magnitude of errors must be understood. Here, we report a source of biological variability in microarray experiments with stably transfected cell lines.

Functional analysis of the relationship between the neurofibromatosis 2 tumor suppressor and its binding partner, hepatocyte growth factor-regulated tyrosine kinase substrate.

Individuals with the neurofibromatosis 2 (NF2) inherited tumor predisposition syndrome are prone to the development of nervous system tumors, including schwannomas and meningiomas. The NF2 tumor suppressor protein, merlin or schwannomin, inhibits cell growth and motility as well as affects actin cytoskeleton-mediated processes. Merlin interacts with several proteins that might mediate merlin growth suppression, including hepatocyte growth factor-regulated tyrosine kinase substrate (HRS or HGS).

Functional analysis of neurofibromatosis 2 (NF2) missense mutations.

Neurofibromatosis 2 (NF2) is a tumor predisposition syndrome in which affected individuals develop nervous system tumors at an increased frequency. The most common tumor in individuals with NF2 is the schwannoma, which is composed of neoplastic Schwann cells lacking NF2 gene expression. Moreover, inactivation of the NF2 gene is observed in nearly all sporadic schwannomas, suggesting that the NF2 gene is a critical growth regulator for Schwann cells.

The NF2 tumor suppressor gene product, merlin, mediates contact inhibition of growth through interactions with CD44.

The neurofibromatosis-2 (NF2) gene encodes merlin, an ezrin-radixin-moesin-(ERM)-related protein that functions as a tumor suppressor. We found that merlin mediates contact inhibition of growth through signals from the extracellular matrix. At high cell density, merlin becomes hypo-phosphorylated and inhibits cell growth in response to hyaluronate (HA), a mucopolysaccharide that surrounds cells.

The protein 4.1 tumor suppressor, DAL-1, impairs cell motility, but regulates proliferation in a cell-type-specific fashion.

The neurofibromatosis 2 (NF2) tumor suppressor belongs to the Protein 4.1 family of molecules that link the actin cytoskeleton to cell surface glycoproteins. We have previously demonstrated that the NF2 protein, merlin, can suppress cell growth in vitro and in vivo as well as impair actin cytoskeleton-associated processes, such as cell spreading, attachment, and motility.

The NF2 interactor, hepatocyte growth factor-regulated tyrosine kinase substrate (HRS), associates with merlin in the "open" conformation and suppresses cell growth and motility.

The neurofibromatosis 2 tumor suppressor protein, merlin or schwannomin, functions as a negative growth regulator; however, its mechanism of action is not known. In an effort to determine how merlin regulates cell growth, we analyzed a recently identified novel merlin interactor, hepatocyte growth factor-regulated tyrosine kinase substrate (HRS). We demonstrate that regulated overexpression of HRS in rat schwannoma cells results in similar effects as overexpression of merlin, including growth inhibition, decreased motility and abnormalities in cell spreading.

Neurofibromatosis 2 tumor suppressor protein, merlin, forms two functionally important intramolecular associations.

The neurofibromatosis 2 (NF2) tumor suppressor gene product, merlin (schwannomin) forms an intramolecular association that is required for negative growth regulation in vitro and in vivo. In an effort to develop a molecular model for merlin relevant to its tumor suppressor function, we further characterized merlin intramolecular folding. We now demonstrate that merlin forms two intramolecular associations, one between the amino terminal (N-term) domain and the carboxyl terminal (C-term) domain and another within the amino terminal domain (N-term/N-term) itself.

Increased expression of the NF2 tumor suppressor gene product, merlin, impairs cell motility, adhesionand spreading.

The neurofibromatosis 2 ( NF2 ) gene product, merlin, is a tumor suppressor protein mutated in schwanno-mas and several other tumors. Merlin, which shares significant homology with the actin-associated proteins ezrin, radixin and moesin (ERM proteins), inhibits cell growth when overexpressed in cell lines. The similarities between merlin and ERM proteins suggest that merlin's growth-regulatory capabilities may be due to alterations in cytoskeletal function.

Cloning and identification of annexin II as an autocrine/paracrine factor that increases osteoclast formation and bone resorption.

Autocrine products of osteoclasts such as interleukin-6 may play an important role in normal osteoclast formation and activity. To identify novel stimulatory factors for osteoclasts, we have prepared a mammalian cDNA expression library generated from highly purified human osteoclast-like multinucleated cells (MNC) formed in long term bone marrow cultures and screened this library for autocrine factors that enhance MNC formation. A candidate clone which stimulated MNC formation was isolated.

Tartrate-resistant acid phosphatase gene expression as a facile reporter gene for screening transfection efficiency in mammalian cell cultures.

The efficiency of DNA transfection into mammalian cell cultures has been monitored using a variety of reporter assays. However, the common procedures are expensive, time-consuming and usually cannot identify the transfected cell population directly. In the present communication we describe a simple, inexpensive and efficient method to directly identify DNA transfection in mammalian cells using tartrate-resistant acid phosphatase (TRAP) gene expression.

Xeroderma pigmentosum variant cells are not defective in the repair of (6-4) photoproducts.

Using radioimmunoassays specific for (6-4) photoproducts and cyclobutane dimers, Xeroderma pigmentosum variant cells appear to have a normal capacity for the repair of each of these lesions. However, these assays measure an early stage in the repair pathway and we do not exclude the possibility that repair is not successfully completed following UV irradiation and excision of DNA photoproducts.

Further characterisation of a polyclonal antiserum for DNA photoproducts: the use of different labelled antigens to control its specificity.

Synthetic polynucleotides irradiated with far (254 nm) or near (320 nm) UV-light were used to characterise 3 different radioimmunoassay systems. Antiserum raised against DNA irradiated with a high dose of far-UV-light was found to have at least 2 antibody populations. A competitive assay in which the labelled antigen was irradiated at 254 nm was found to be specific for Pyr(6-4)Pyo adducts, the antibody-binding sites being sensitive to a secondary photolytic dose of 320-nm light.

(6-4)Photoproducts are removed from the DNA of UV-irradiated mammalian cells more efficiently than cyclobutane pyrimidine dimers.

A polyclonal antiserum raised against UV-irradiated DNA can be used to assay cyclobutane pyrimidine dimers and Pyr(6-4)Pyo photoproducts specifically by changing the nature of the 32P-labelled antigen. Pyr(6-4)Pyo photoproducts were removed faster than cyclobutane dimers in UV-irradiated human, hamster and mouse cells. Xeroderma pigmentosum cells from complementation groups A, C and D were deficient in the repair of both lesions.

Biological consequences of photoproducts in mammalian cell DNA partially substituted with 5-bromouracil.

The response of Chinese hamster ovary cells in which 10 per cent of the thymine of one DNA strand was substituted with bromouracil (BU) was compared with normal cells following u.v. irradiation.