Project Summary:
It is becoming increasingly clear that one of the ways that cells interpret and encode information into multiple cell
fates is by multiplexing information through dynamic encoding. This is especially true for the MAPK/Erk pathway,
that governs many cell processes including cell proliferation, differentiation and migration. For years, how such
diverse outcomes were controlled by the same pathway remained elusive, but the advent of single cell studies
and optogenetics has elucidated the many ways in which Erk activity can be interpreted into distinct cell fates,
and even more recently, the role of dynamics in these complex decisions. The role of developmental Erk
dynamics in determining and coordinating human gastrulation, however, has not yet been investigated. We will
combine live cell kinase activity reporters and optogenetic control over intracellular signaling pathways to probe
the role of ERK dynamics in positioning and coordinating the three germ layers. Additionally, we will uncover
whether RASopathy causing mutations influence human gastrulation to pace the way for potential therapeutic
intervention.
This proposal brings together recent advances in stem cell and molecular engineering. We utilize
advances in 2D micropatterning, cellular optogenetic control, live cell kinase activity reporters and CRISPR Cas9
genome editing. Together, these technologies give us unprecedented control over and visualization of
microengineered models of human gastrulation, thereby enabling us to investigate the principles of dynamic
information transmission. Our platform does not face the same ethical barriers that have limited human embryo
research, allowing us to provide otherwise unavailable information about human embryonic development. In this
proposal we focus on the role of Erk signaling dynamics in coordinating the three germ layers, as well as uncover
impact of RASopathy mutations. In Aim 1 we will image and quantify Erk signaling dynamics using the Erk kinase
translocation reporter during the process of gastrulation and determine which features of signaling dynamics are
predictive of germ layer fate. Aim 2 will allow us to identify which of these dynamical features are sufficient to
determine the cell fate outcome using cellular optogenetics. Finally, in Aim 3 we will uncover whether RASopathy
mutations lead to gastrulation defects and investigate whether these are linked to disruption to Erk dynamical
signatures using CRISPR Cas9 gene editing and our 2D gastruloid model. Approaching this cell biological
question from a systems level perspective, using reproducible precisely controllable tools that are otherwise
unavailable without optogenetics and microengineered platforms, has the potential to shine new light on the field.