CELL CULTURES
The use of cultured cell lines as model systems for normal tissue is limited by the molecular alterations accompanying the immortalisation process, including changes in the mRNA and miRNA repertoire. Therefore, identification of cell lines with normal-like expression profiles is of paramount importance in studies of normal gene regulation.
The mRNA and miRNA expression profiles of several breast cell lines of cancerous or normal origin were measured using printed slide arrays, Luminex bead arrays and real-time RT-PCR.
We demonstrate that the mRNA expression profiles of two breast cell lines are similar to that of normal breast tissue: HB4a, immortalised normal breast epithelium, and PMC42, a breast cancer cell line that retains progenitor pluripotency allowing in culture differentiation to both secretory and myoepithelial fates.
In contrast, only PMC42 exhibits a normal-like miRNA expression profile. We identified a group of miRNAs that are highly expressed in normal breast tissue and PMC42 but are lost in all other cancerous and normal-origin breast cell lines, and observed a similar loss in immortalised lymphoblastoid cell lines compared to healthy uncultured B cells. Moreover, like tumour suppressor genes, these miRNAs are lost in a variety of tumours. We show that the mechanism leading to the loss of these miRNAs in breast cancer cell lines has genomic, transcriptional and post-transcriptional components.
We propose that despite its neoplastic origin, PMC42 is an excellent molecular model for normal breast epithelium, providing a unique tool to study breast differentiation and the function of key miRNAs which are typically lost in cancer.
- "PMC42, a breast progenitor cancer cell line, has normal-like mRNA and miRNA transcriptomes" Anna Git, Inmaculada Spiteri, Cherie Blenkiron, Mark Dunning, Jessica CM Pole, Suet-Feung Chin, Yanzhong Wang, James Smit, Frederick J Livesey and Carlos Caldas Breast Cancer Research 2008, 10:R54doi:10.1186/bcr2109
BACTERIOLOGY
Pathogenic spirochetes are bacteria that cause a number of emerging and re-emerging diseases worldwide, including syphilis, leptospirosis, relapsing fever, and Lyme borreliosis. They navigate efficiently through dense extracellular matrix and cross the blood-brain barrier by unknown mechanisms. Due to their slender morphology, spirochetes are difficult to visualize by standard light microscopy, impeding studies of their behavior in situ.
We engineered a fluorescent infectious strain of Borrelia burgdorferi, the Lyme disease pathogen, which expressed green fluorescent protein (GFP). Real-time 3D and 4D quantitative analysis of fluorescent spirochete dissemination from the microvasculature of living mice at high resolution revealed that dissemination was a multi-stage process that included transient tethering-type associations, short-term dragging interactions, and stationary adhesion. Stationary adhesions and extravasating spirochetes were most commonly observed at endothelial junctions, and translational motility of spirochetes appeared to play an integral role in transendothelial migration.
To our knowledge, this is the first report of high resolution 3D and 4D visualization of dissemination of a bacterial pathogen in a living mammalian host, and provides the first direct insight into spirochete dissemination in vivo.
- "Real-Time High Resolution 3D Imaging of the Lyme Disease Spirochete Adhering to and Escaping from the Vasculature of a Living Host" Moriarty TJ, Norman MU, Colarusso P, Bankhead T, Kubes P, et al. (2008) PLoS Pathog 4(6): e1000090. doi:10.1371/journal.ppat.1000090
IMMUNOLOGY
MHC class I family members serve multiple functions beyond antigen presentation. We provide insight into the structure, expression and function of the Mill subfamily. This family includes two surface glycoproteins, Mill1 and Mill2. Protein sequences for Mill1 and Mill2 are most highly related to the NKG2D ligands, MICA and MICB, but neither of them bound to NKG2D.Computer-based protein modelling indicated that hereditary haemochromatosis protein (HFE), a molecule involved in iron uptake, was most similar. Mill1 and Mill2 were observed on cycling thymocytes, proliferating smooth muscle cells and fibroblasts. Using soluble Mill proteins, we found evidence for a soluble ligand in serum. Like HFE, the Mill family may be involved in nutrient metabolism. Skin was one of the only three organs found to express transcripts for both Mill1 and Mill2. Addition of antibodies specific for Mill2 to wounded skin enhanced healing.
Our results suggest a role for the Mill proteins in cellular metabolism, with possible therapeutic significance.
- "A role for the MHC class I-like Mill molecules in nutrient metabolism and wound healing" Brian A Rabinovich, Randal R Ketchem, Martin Wolfson, Lynn Goldstein, Marylin Skelly and David Cosman Immunology and Cell Biology advance online publication 17 June 2008; doi: 10.1038/icb.2008.41
