Tracing Cell Lineages

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DESCRIPTION (provided by applicant): The adult human body is composed of trillions of cells that all originated from a single fertilized egg cell. In the adult, most tissues are in a state of constant flux, where old cells die and new cells are created from resident populations of stem cells, changing their identities in mysterious ways. The fluidity of change among cell populations initiate from the moment we are conceived- to our final breath of life. Multicellular life dances t the music of a highly ordered process, directed by a score that is not well understood. Disease such as cancer emerges when cells lose their directions, and divide in an uncontrolled manner, losing their identities. Other diseases are hallmarked by a loss of cells, triggered by unwanted self-elimination such as apoptosis or autoimmunity. One of the greatest struggles in biology is to understand these fundamental processes, at the cellular and molecular level. Our idea is to develop a new tool that will help us track the ancestry of individual cells, using a novel DNA barcoding technology. This proposal describes a new approach for tracking the evolutionary history of individual cells- at the most possible granular level, the individual cells. We take advantage of new technologies (deep sequencing and programmable DNA binding enzymes), combining them in a way to create a single cell lineage tracer in which each cell writes its own unique barcode. This system is comprised of a molecular 'typewriter' that types a unique barcode every time a cell goes into cell cycle. Moreover, this written barcode accumulates with each future generation. Our vision is to introduce this system into fertlized zygotes, were mouse lines will be developed. In essence every cell in the mouse will contain a unique barcode, and each barcode would contain information on its ancestral lineage, tracing back to the initial fertilized zygote. We believe that developing a quantitative approach for defining single cell inheritance lineages will transform how the next generation of developmental and disease biologists approach their problems.