Biomedical subjects

Vasily Shinin

Publications and source records attributed to Vasily Shinin.

3 recordsLinked to original sources

PubMed2006

Asymmetric division and cosegregation of template DNA strands in adult muscle satellite cells.

Satellite cells assure postnatal skeletal muscle growth and repair. Despite extensive studies, their stem cell character remains largely undefined. Using pulse-chase labelling with BrdU to mark the putative stem cell niche, we identify a subpopulation of label-retaining satellite cells during growth and after injury. Strikingly, some of these cells display selective template-DNA strand segregation during mitosis in the muscle fibre in vivo, as well as in culture independent of their niche, indicating that genomic DNA strands are nonequivalent. Furthermore, we demonstrate that the asymmetric cell-fate determinant Numb segregates selectively to one daughter cell during mitosis and before differentiation, suggesting that Numb is associated with self-renewal. Finally, we show that template DNA cosegregates with Numb in label-retaining cells that express the self-renewal marker Pax7. The cosegregation of 'immortal' template DNA strands and their link with the asymmetry apparatus has important implications for stem cell biology and cancer.

Animals↗

PubMed2005

Segmenting and tracking fluorescent cells in dynamic 3-D microscopy with coupled active surfaces.

Cell migrations and deformations play essential roles in biological processes, such as parasite invasion, immune response, embryonic development, and cancer. We describe a fully automatic segmentation and tracking method designed to enable quantitative analyses of cellular shape and motion from dynamic three-dimensional microscopy data. The method uses multiple active surfaces with or without edges, coupled by a penalty for overlaps, and a volume conservation constraint that improves outlining of cell/cell boundaries. Its main advantages are robustness to low signal-to-noise ratios and the ability to handle multiple cells that may touch, divide, enter, or leave the observation volume. We give quantitative validation results based on synthetic images and show two examples of applications to real biological data.

Algorithms↗

PubMed2004

Mrf4 determines skeletal muscle identity in Myf5:Myod double-mutant mice.

In vertebrates, skeletal muscle is a model for the acquisition of cell fate from stem cells. Two determination factors of the basic helix-loop-helix myogenic regulatory factor (MRF) family, Myf5 and Myod, are thought to direct this transition because double-mutant mice totally lack skeletal muscle fibres and myoblasts. In the absence of these factors, progenitor cells remain multipotent and can change their fate. Gene targeting studies have revealed hierarchical relationships between these and the other MRF genes, Mrf4 and myogenin, where the latter are regarded as differentiation genes. Here we show, using an allelic series of three Myf5 mutants that differentially affect the expression of the genetically linked Mrf4 gene, that skeletal muscle is present in the new Myf5:Myod double-null mice only when Mrf4 expression is not compromised. This finding contradicts the widely held view that myogenic identity is conferred solely by Myf5 and Myod, and identifies Mrf4 as a determination gene. We revise the epistatic relationship of the MRFs, in which both Myf5 and Mrf4 act upstream of Myod to direct embryonic multipotent cells into the myogenic lineage.

Alleles↗