Ph.D. University of Geneva, Switzerland 2004
As a doctoral student with Denis Duboule (University of Geneva, Switzerland), I generated mouse lines with single loxP sites interspersed in the HoxD gene complex, and used meiotic Cre recombination intrans to produce over twenty mouse lines with systematic gene(s) deletions and duplications. This unique mutant array allowed novel insight into the mechanism of colinearity, the graded temporal and spatial transcriptional activation of contiguous Hoxgenes along body axes (Tarchini and Duboule, 2005). My work contributed to understanding how Hoxgenes regulate Sonic hedghog to pattern the antero-posterior axis of the limb (Tarchini et al., 2006), and how antero-posterior motor neuron identity depends on Hox colinearity in the spinal cord (Tarchini et al., 2005).
As a post-doctoral fellow with Michel Cayouette (IRCM, Montréal, Canada), my questions about temporal and spatial patterning adopted a more cellular resolution. While contributing to the laboratory interests on retinal neurogenesis (Tarchini et al., 2012; Alsiö, Tarchini et al., 2013), I initiated a more personal project following the hypothesis that proteins orienting the mitotic spindle can be recruited post-mitotically to polarize differentiating cells. These investigations brought new ideas on how hair cells in the inner ear acquire planar polarity crucial for sensory perception (Tarchini et al., 2013 ). This work is also the foundation of my independent research program at The Jackson Laboratory.
Fundamental to our interaction with the world, hearing is first encoded by epithelial hair cells in the inner ear. These mechanosensory cells transform the sound-induced deflection of movement detectors protruding at the apical surface into electrical impulses relayed to the brain. Our research goals are to unravel the molecular mechanisms shaping hair cells for perception. Sensory ability requires striking polarization of the cytoskeleton at multiple levels during development. In the epithelial plane, we recently showed that polarized exclusion of microvilli frames the V-shaped bundle they form in individual cells. Across neighboring cells, V-shaped bundles adopt a uniform orientation, a property known as “planar cell polarity”. Orthogonal to the epithelial plane, microvilli grow into stereocilia of graded heights, forming the staircase-like mechanosensory organ of the cell. How are these distinct levels of cytoskeleton polarity implemented and interconnected? Understanding where morphogenesis meets function will not only add to our understanding of hereditary hearing loss and suggest potential treatments, but it will also be critical for achieving hair cell regeneration after injury, a fascinating property of lower vertebrates lost in mammals.
- Tarchini, B., Jolicoeur, C., and Cayouette, M. (2013). A molecular blueprint at the apical surface establishes planar asymmetry in cochlear hair cells. Developmental Cell 27, 88-102. Read Abstract
- Alsio, J.M., Tarchini, B., Cayouette, M., and Livesey, F.J. (2013). Ikaros promotes early-born neuronal fates in the cerebral cortex. Proc Natl Acad Sci USA 110, E716-725. Read Abstract
- Tarchini, B., Jolicoeur, C., and Cayouette, M. (2012). In vivo evidence for unbiased Ikaros retinal lineages using an Ikaros-Cre mouse line driving clonal recombination. Developmental Dynamics 241, 1973-1985. Read Abstract
- Tschopp, P., Tarchini, B., Spitz, F., Zakany, J., and Duboule, D. (2009). Uncoupling time and space in the collinear regulation of Hox genes. PLoS Genetics 5, e1000398.
- Duboule, D., Tarchini, B., Zakany, J., and Kmita, M. (2007). Tinkering with constraints in the evolution of the vertebrate limb anterior-posterior polarity. Novartis Foundation Symposium 284, 130-137; discussion 138-141, 158-163.
- Tarchini, B., Duboule, D., and Kmita, M. (2006). Regulatory constraints in the evolution of the tetrapod limb anterior-posterior polarity. Nature 443, 985-988.
- Tarchini, B., and Duboule, D. (2006). Control of Hoxd genes’ collinearity during early limb development. Developmental Cell 10, 93-103. Read Abstract
- Tarchini, B., Huynh, T.H., Cox, G.A., and Duboule, D. (2005). HoxD cluster scanning deletions identify multiple defects leading to paralysis in the mouse mutant Ironside. Genes & Development 19, 2862-2876. Read Abstract
- Kmita, M., Tarchini, B., Zakany, J., Logan, M., Tabin, C.J., and Duboule, D. (2005). Early developmental arrest of mammalian limbs lacking HoxA/HoxD gene function. Nature 435, 1113-1116.
- Kmita, M., Tarchini, B., Duboule, D., and Herault, Y. (2002). Evolutionary conserved sequences are required for the insulation of the vertebrate Hoxd complex in neural cells. Development 129, 5521-5528.