Uses K Electrical Signalling to Orchestrate Host Sensing, Inter-Bacterial Communication and Differentiation.

Prokaryotic communities coordinate quorum behaviour in response to external stimuli to control fundamental processes including inter-bacterial communication. The obligate intracellular bacterial pathogen adopts two developmental forms, invasive elementary bodies (EBs) and replicative reticulate bodies (RBs), which reside within a specialised membrane-bound compartment within the host cell termed an inclusion. The mechanisms by which this bacterial community orchestrates different stages of development from within the inclusion in coordination with the host remain elusive.

Bridging the continuum: Analysis of the alignment of undergraduate and postgraduate accreditation standards.

Several influential national/international bodies including The Bologna Accord, The Carnegie Foundation and The Future of Medical Education in Canada (FMEC) have called for increased coordination across the medical education continuum. FMEC recognizes accreditation as a "powerful lever" and encourages the alignment of undergraduate and postgraduate standards. The Carnegie Foundation includes a similar call for the creation of a more coherent accreditation system.

Fusion tyrosine kinase NPM-ALK Deregulates MSH2 and suppresses DNA mismatch repair function novel insights into a potent oncoprotein.

The fusion tyrosine kinase NPM-ALK is central to the pathogenesis of ALK-positive anaplastic large cell lymphoma (ALK(+)ALCL). We recently identified that MSH2, a key DNA mismatch repair (MMR) protein integral to the suppression of tumorigenesis, is an NPM-ALK-interacting protein. In this study, we found in vitro evidence that enforced expression of NPM-ALK in HEK293 cells suppressed MMR function.

Inhibition of p38 MAPK enhances ABT-737-induced cell death in melanoma cell lines: novel regulation of PUMA.

The mitogen-activated protein kinase (MAPK) pathway is constitutively activated in the majority of melanomas, promoting cell survival, proliferation and migration. In addition, anti-apoptotic Bcl-2 family proteins Mcl-1, Bcl-xL and Bcl-2 are frequently overexpressed, contributing to melanoma's well-documented chemoresistance. Recently, it was reported that the combination of MAPK pathway inhibition by specific MEK inhibitors and Bcl-2 family inhibition by BH3-mimetic ABT-737 synergistically induces apoptotic cell death in melanoma cell lines.

Defining the DNA mismatch repair-dependent apoptotic pathway in primary cells: evidence for p53-independence and involvement of centrosomal caspase 2.

Many studies have shown that DNA mismatch repair (MMR) has a role beyond that of repair in response to several types of DNA damage, including ultraviolet radiation (UV). We have demonstrated previously that the MMR-dependent component of UVB-induced apoptosis is integral to the suppression of UVB-induced tumorigenesis. Here we demonstrate that Msh6-dependent UVB-induced apoptotic pathway is both activated via the mitochondria and p53-independent.

RNA silencing of Mcl-1 enhances ABT-737-mediated apoptosis in melanoma: role for a caspase-8-dependent pathway.

Background: Malignant melanoma is resistant to almost all conventional forms of chemotherapy. Recent evidence suggests that anti-apoptotic proteins of the Bcl-2 family are overexpressed in melanoma and may contribute to melanoma's striking resistance to apoptosis. ABT-737, a small-molecule inhibitor of Bcl-2, Bcl-xl and Bcl-w, has demonstrated efficacy in several forms of leukemia, lymphoma as well as solid tumors.

Non-tumor cells from an MSH2-null individual show altered cell cycle effects post-UVB.

The multi-functionality of the DNA mismatch repair (MMR) proteins has been demonstrated by their role in regulation of the cell cycle and apoptosis, as well as DNA repair. Using a unique MSH2-/- non-tumor human lymphoblastoid cell line we show that MMR facilitates G2/M arrest after UVB-induced DNA damage. Deficiency in MSH2 leads to a decrease in the induction of G2/M cell cycle checkpoint following UVB radiation in MSH2-null non-tumor cells.

The associated contributions of p53 and the DNA mismatch repair protein Msh6 to spontaneous tumorigenesis.

DNA mismatch repair (MMR) is a highly conserved system that repairs DNA adducts acquired during replication, as well as some forms of exogenous/endogenous DNA damage. Additionally, MMR proteins bind to DNA adducts that are not removed by MMR and influence damage-response mechanisms other than repair. Hereditary non-polyposis colorectal cancer, as well as mouse models for MMR deficiency, illustrate that MMR proteins are required for maintenance of genetic stability and tumor suppression.

A lack of DNA mismatch repair on an athymic murine background predisposes to hematologic malignancy.

Inheritance of a germline mutation in one of the DNA mismatch repair genes predisposes human individuals to hereditary nonpolyposis colorectal cancer, characterized by development of tumors predominantly in the colon, endometrium, and gastrointestinal tract. Mice heterozygous for a mismatch repair-null mutation generally do not have an increased risk of neoplasia. However, mice constitutively lacking mismatch repair are prone to tumor development from an early age, particularly thymic lymphomas.

DNA mismatch repair proteins promote apoptosis and suppress tumorigenesis in response to UVB irradiation: an in vivo study.

DNA mismatch repair (MMR) proteins are integral to the maintenance of genomic stability and suppression of tumorigenesis due to their role in repair of post-replicative DNA errors. Recent data also support a role for MMR proteins in cellular responses to exogenous DNA damage that does not involve removal of DNA adducts. We have demonstrated previously that both Msh2- and Msh6-null primary mouse embryonic fibroblasts are significantly less sensitive to UVB (ultraviolet B)-induced cytotoxicity and apoptosis than wild-type control cells.

DNA mismatch repair protein Msh6 is required for optimal levels of ultraviolet-B-induced apoptosis in primary mouse fibroblasts.

Recent data support a role for DNA mismatch repair in the cellular response to some forms of exogenous DNA damage beyond that of DNA repair; cells with defective DNA mismatch repair have partial or complete failure to undergo apoptosis and/or G2M arrest following specific types of damage. We propose that the DNA mismatch repair Msh2/Msh6 heterodimer, responsible for the detection of DNA damage, promotes apoptosis in normal cells, thus protecting mammals from ultraviolet-induced malignant transformation. Using primary mouse embryonic fibroblasts derived from Msh6+/+ and Msh6-/- mice, we compare the response of DNA-mismatch repair-proficient and -deficient cells to ultraviolet B radiation.

DNA mismatch repair proteins: potential guardians against genomic instability and tumorigenesis induced by ultraviolet photoproducts.

In addition to their established role in repairing post-replicative DNA errors, DNA mismatch repair proteins contribute to cell cycle arrest and apoptosis in response to a wide range of exogenous DNA damage (e.g., alkylation-induced lesions).

Mammalian DNA mismatch repair protects cells from UVB-induced DNA damage by facilitating apoptosis and p53 activation.

DNA mismatch repair (MMR) is integral to the maintenance of genomic stability and more recently has been demonstrated to affect apoptosis and cell cycle arrest in response to a variety of adducts induced by exogenous agents. Comparing Msh2-null and wildtype mouse embryonic fibroblasts (MEFs), both primary and transformed, we show that Msh2 deficiency results in increased survival post-UVB, and that UVB-induced apoptosis is significantly reduced in Msh2-deficient cells. Furthermore, p53 phosphorylation at serine 15 is delayed or diminished in Msh2-deficient cells, suggesting that Msh2 may act upstream of p53 in a post-UVB apoptosis or growth arrest response pathway.

An intronic polymorphism of the hMLH1 gene contributes toward incomplete genetic testing for HNPCC.

Hereditary non-polyposis colorectal cancer (HNPCC) is a common hereditary cancer. Genetic testing is complicated by the multiple DNA mismatch repair genes that underlie the disorder. Many suspected HNPCC families have no germ-line mutation identified.

Application of inter-simple sequence repeat PCR to mouse models: assessment of genetic alterations in carcinogenesis.

Genomic instability is believed to play a significant role in cancer development by facilitating tumor progression and tumor heterogeneity. Inter-simple sequence repeat (inter-SSR) PCR has been proved to be a fast and reproducible technique for quantitation of genomic instability (amplifications, deletions, translocations, and insertions) in human sporadic tumors. However, the use of inter-SSR PCR in animal models of cancer has never been described.

A homozygous germ-line mutation in the human MSH2 gene predisposes to hematological malignancy and multiple café-au-lait spots.

Individuals with a germ-line mutation in one of the DNA mismatch repair (MMR) genes are at significant risk for colorectal cancer and other tumors. Three families have previously been reported with individuals homozygous for mutations in the MMR gene MLH1 that are predicted to compromise MMR. These individuals develop hematological malignancies and/or neurofibromatosis type 1 at an early age.