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Tag Archives: muscle

Friday Science Review: May 7, 2010

Amazing!  Three Nature papers this week…

Cracking the Code: The human body is much more complex than the 20,000 or so genes that are encoded in our DNA.  This multiplicity of genetic messages is enhanced by alternative gene splicing, a process where different segments of DNA exons are spliced together to create a different gene message.  It is possible to create hundreds of new messages from a single gene.  The so called “splicing code” or rules that determines how and where a particular part of a gene is spliced with another segment was deciphered by researchers at the University of Toronto.  They can now accurately predict how genetic messages are rearranged on a large scale.  Hundreds of different RNA features are taken into account including certain factors in specific tissues to give rise to tissue specific expression.  This is an amazing discovery by Drs. Brendan Frey and Benjamin Blencowe that garnered the cover story in this week’s Nature journal.

Stem Cells on Hormones: The ovarian hormone, progesterone, stimulates breast stem cells as its levels peak during the natural reproductive cycle.  Researchers observed up to a 14-fold expansion of breast stem cells at peak progesterone levels in a mouse model.  This is the first evidence of a direct link between hormones and breast stem cells.  Since cancers are thought to initiate from stem cells, if there are other oncogenic factors pushing the system this may be a critical point that ultimately drives the start of a cancer.  There are implications of this study to further understanding how reproductive history is a strong risk factor for breast cancer and may lead to therapeutic intervention.  The research team at Princess Margaret Hospital, University Health Network was led by Dr. Rama Khokha and describes their work in Nature.

Reversing HER2 Breast Cancer: Through genomic studies of HER2 positive breast cancer, it was noted that the 14-3-3sigma gene was frequently missing.  After several years of hard work focusing on this gene, researchers have demonstrated that the 14-3-3sigma gene does indeed play a specific role in the development and function of breast epithelial tissue.  In the absence of 14-3-3sigma, the normally organized and polarized sheets of epithelial cells clump together and lose polarity.  It is this loss of organization without 14-3-3sigma that likely contributes to breast cancer progression.  From a therapeutic standpoint, the reintroduction of 14-3-3sigma into HER2 positive breast cancer cells resulted in the restoration of cell polarity and opens a window for further studies as a pathway to target.  Dr. William Muller (my former mentor) and his team at McGill University describe their research in the early edition of Genes and Development.

Bionic Muscle: Artificial proteins were assembled together in a fashion that mimics the molecular spring structure of a muscle protein called Titin, which is a very large protein that gives muscle tissue its unique properties of strength, extensibility and resilience.  This is why muscle has superior elasticity.  The biomaterial looks like a string of beads and although it exhibits only some of the mechanical characteristics of muscle tissue, its structure can be adjusted to provide specific properties of different types of muscle.  There are obvious future applications of this technology in regenerative medicine and tissue engineering.  Drs. Hongbin Li and John Gosline at the University of British Columbia present their work in this week’s Nature journal.

Friday Science Review: January 22, 2010

Some really exciting research in this week’s review…

Special (RNAi) Delivery: One of the obstacles for RNAi based therapeutics is the difficulty in getting the RNAi into the cells efficiently to invoke a positive response.  Vancouver based Tekmira Pharmaceuticals (TSX: TKM.TO), in partnership with Alnylam Pharmaceuticals (Nasdaq: ALNY) and researchers at the University of British Columbia, Drs. Pieter Cullis and Marco Ciufolini, developed a new and improved RNAi delivery method that is 10X better than their standard delivery platform.  Using their knowledge of lipid structure and how specific features influences delivery into cells, they used a rational design approach to develop a new cationic lipid, DLin-KC2-DMA (KC2), that is used with their current SNALP system (stable nucleic acid-lipid particles) to achieve the remarkable results.  Details of the study are reported in this week’s issue of Nature Biotechnology.

Resolving Stem Cell Populations: The differentiation of stem cells is a complex multi-step process that is not fully understood.   With each step, the potential of that stem cell becomes more and more restricted.  Researchers performed a series of intricate detailed studies on cell populations to resolve distinct Intermediate Term Reconstituting Hematopoietic Stem Cells or ITRC (versus long- and short-term populations).  The significance of this key finding is that researchers who are interested in harnessing the potential of long-term reconstituting hematopoietic stem cells can more accurately study a pure population of true, self-renewing stem cells with homogeneous characteristics.  Prior to this new “intermediate-term” identification, the majority of “long-term” cells were actually comprised of intermediate-term cells.  Dr. Norman Iscove and his team at the University Health Network describe their work in the latest issue of Cell Stem Cell.

Fishing for New Drugs: A high-throughput behavioural monitoring system to observe the response of Zebrafish to neuroactive chemical compounds should help expedite the discovery of new drugs for neurological disorders.  Researchers setup a video system and applied “behavioural barcodes” that they say can track the effects of 14,000 chemicals on zebrafish behaviour.  The capacity of this large-scale screen is unique and the use of zebrafish is quite informative because they are transparent, genetically tractable, and more similar to humans than you might think.  In this platform, response to two strong light pulses after exposure to chemicals is monitored and the observations are translated into barcodes that make data analysis of this magnitude a lot more manageable.  Drs. Jennifer Bryan and Rick White at UBC collaborated with Harvard researchers and published their study in Nature Chemical Biology.

Intrinsic Stimulator of Muscle Regeneration: A new subpopulation of cells in muscle tissue that contribute to muscle injury repair has been identified.  The surprise is that these cells, called fibro/adipogenic progenitors (FAPs), are derived from a different developmental lineage as muscle cells.  These fat-lineage cells, which are resident in muscle tissue, are ‘activated’ in response to muscle damage but they do not become muscle cells.  Instead, they release factors that promote and enhance muscle progenitors in the myogenesis repair process.  The conundrum, however, is that too much of these FAPs can lead to fibrosis and contribute to muscle disorders.  The study, reported in Nature Cell Biology, was led by Dr. Fabio Rossi at the University of British Columbia.

Pharmacoviral Therapy for Gliomas: Oncolytic viruses (VSVs) are used in the treatment against malignant gliomas but are limited in efficacy due to the viral induced IFN (interferon) response – one of our body’s natural defense mechanism.  Knowledge of the molecular mechanisms involving the mTOR pathway in IFN production led researchers to investigate the use of rapamycin, an mTOR inhibitor, in conjunction with the VSVs.  This “pharmacoviral” combinatorial approach was very successful when tested in rats with malignant gliomas and represents a potentially new therapeutic strategy.  Dr. Nahum Sonenberg and his team at McGill University are experts in the mTOR pathway and describe their work in the Proceedings of the National Academy of Sciences.

Friday Science Review: December 11, 2009

WOW!  A busy week in the bioscience world…

Pull Down Your ‘SOCS’ and Grow Some Nerves: A long standing question is how to get mature neurons, which stop growing at around the age of two, to start growing again after sustaining nerve damage.  The answer may lie in a protein called SOCS3 (suppressor of cytokine signaling 3).  SOCS3 controls neuronal growth in adults but when it is absent (in a knockout mouse model), axons can regenerate after nerve injury.  This process may be enhanced by supplying a cocktail of neurotrophic growth factors that the researchers also identified in their study.  This is a very important discovery that will push regenerative medicine to new therapeutic strategies.  Dr. Patrice Smith started the research as a postdoctoral fellow at Harvard University and now runs her own lab at Carleton University.  The study is published in the latest edition of Neuron.  There is also an inspirational story about Dr. Smith in the Globe and Mail.

Protecting your Brain after a Stroke: Following a stroke, neurons are at risk of permanent damage caused by overactivation of NMDARs (N-methyl-D-aspartate glutamate receptors).  A key molecular step leading to this excitotoxic neuronal death was discovered in this recent study.  The trauma causes degradation of Insig-1 (insulin-induced gene-1), which triggers the activation of the transcription factor SREBP-1 (sterol regulatory element binding protein-1).  However, when they blocked the activation of SREBP-1 they were successful in reducing the neuronal damage.  This is a promising target for generating therapeutic drugs aimed at minimizing the detrimental effects of strokes and brain trauma.  The research team was guided by Dr. Yu Tian Wang at the University of British Columbia and the study is reported in the latest Nature Medicine.

Breakthrough in Children’s Brain Cancer Research: A rare pediatric brain tumour called Central Nervous System-Primitive Neuroectodermal Tumours (CNS-PNET) offers a very poor prognosis for young patients.  In this gene expression study, a cluster of microRNAs called C19MC was found to be amplified in the diseased tissue in about 25% of the patients. This cluster acts as an oncogene that enhances cell growth and affects differentiation of neural stem cells.   The new discovery will advance opportunities to study this rare pediatric cancer and possibly use C19MC as a diagnostic marker and/or therapeutic target.  The international study was led by Dr. Annie Huang at SickKids Hospital and is reported in the current issue of Cancer Cell.

Genomics Study on Pathogenic Factors: In a large scale study of bacterial genomes, it was proven broadly across microbial species that many of the bacterial virulence factors are contained within genomic islands or clusters of genes.  The virulence factors are proteins that have more “offensive” functions such as toxins that help the bacteria invade the host.  Another significant outcome of this research is the discovery of potentially new pathogen-associated genes that are present pre-dominantly in pathogenic bacteria but less frequently in the non-pathogenic bacteria.  These factors require a closer look as they may represent novel targets for anti-microbial drug development, a critical area of research to combat the increasing prevalence of drug resistant bacteria.   Dr. Fiona Brinkman’s team at Simon Fraser University conducted the research and is detailed in PLoS One.

Dabigatran vs. Warfarin (round 2): Following up on a study that I mentioned here earlier this year, new research further supports the use of Dabigatran over Warfarin.  Patients with a common clotting disorder called venous thromboembolism (VTE) can benefit from Dabigatran as an equally effective and safe blood thinning treatment but without the complications associated with using Warfarin, which requires frequent visits to the clinic for blood monitoring and dosage adjustments.  The study was conducted by Dr. Sam Schulman at McMaster University and appears in this week’s The New England Journal of Medicine.

Research on Congenital Myopathy in Mice:  University of Toronto scientists have generated a mouse model to study a specific type of skeletal muscle disorder.  The mice express a mutant form of the RyR1 protein (type 1 ryanodine receptor/Ca2+ release channel), which causes a severe form of central core disease (CCD). Symptoms in mice that mimic the human condition include progressive congenital myopathy, respiratory stress, skeletal muscle weakness and impaired mobility.  Their study offers insight and future potential to unravel the mechanism behind the disorder.  Dr. David MacLennan’s research is published in The Proceedings of the National Academy of Sciences.

Here is a list of many more important research reports this week from across the country:

Cofactor-activated phosphorylation is required for inhibition of cortical neuron differentiation by Groucho/TLE1. (Dr. Stefano Stifani, McGill University)

Dlx5 Is a cell autonomous regulator of chondrocyte hypertrophy in mice and functionally substitutes for Dlx6 during endochondral ossification. (Dr. Andrew Bendall, University of Guelph)

Pluripotent transcription factors possess distinct roles in normal versus transformed human stem cells. (Dr. Mickie Bhatia, McMaster University)

Nfil3/E4bp4 is required for the development and maturation of NK cells in vivo. (Dr. Tak Mak, The Campbell Family Institute for Breast Cancer Research and University of Toronto).

A novel enediynyl peptide inhibitor of furin that blocks processing of proPDGF-A, B and proVEGF-C. (Dr. Amik Basak, University of Ottawa)

The specificity of the FOXL2 c.402C>G Somatic mutation: a survey of solid tumors. (Dr. David Huntsman, University of British Columbia)

Nuclear function of Smad7 promotes myogenesis. (Dr. John McDermott, York University)

Asf1-like structure of the conserved Yaf9 YEATS domain and role in H2A.Z deposition and acetylation. (Dr. Michael Kobor, University of British Columbia)


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