Reprogramming towards a germline stem cell fate - Project Summary
Germline cellular immortality underlies the continuation of all sexually reproducing species.
Recent work has identified frequent examples of interconversion between germline and somatic
fates, suggesting plasticity, rather than a strict dichotomy, between germline and soma. In
adults, production of male gametes is driven by germline stem cell (GSC) division. In my
postdoctoral work, I propose to use the powerfully tractable system of the Drosophila
melanogaster male germline to identify necessary factors of immortal germline fate. In addition
to undergoing normal self-renewal and differentiation, GSCs can be generated through
dedifferentiation of spermatogonia, and can be lost through both forced differentiation to germ
cells and transdifferentiation to soma. First, using single-cell RNA sequencing on testes cells in
which the germline is undergoing dedifferentiation, I will reconstruct lineage transitions to
identify genes underlying GSC formation from a differentiated cell, including both germline cell-
autonomous factors and non-autonomous signaling factors. I will validate these data using both
in vivo expression characterization and assays of gene function. Next, I will describe the
transcriptional changes necessary for transdifferentiation of GSCs to somatic cells, identifying
the components that maintain germline identity. Finally, I will leverage discovery of factors
involved in both a) the creation of GSCs from differentiating cells, and b) the loss of GSC
identity that results in somatic cell formation, in order to develop a novel model for inducible
somatic reprogramming to a germline fate. This work will significantly further our understanding
of the factors that confer cellular immortality, and will aid in the development of therapies for
diverse human diseases.
