Pacheco, J. M. | bioRxiv Science

bioRxiv2022

Cell surface receptor kinase FERONIA linked to nutrient sensor TORC1 signaling controls root hair growth at low temperature in Arabidopsis thaliana

Root hairs (RH) are excellent model systems for studying cell size and polarity since they elongate several hundred-fold their original size. Their tip growth is determined both by intrinsic and environmental signals. Although nutrient availability and temperature are key factors for a sustained plant growth, the molecular mechanisms underlying their sensing and downstream signaling pathways remain unclear. Here, we identified that low temperature (10{degrees}C) triggers a strong RH elongation response involving the cell surface receptor kinase FERONIA (FER) and the nutrient sensing TOR Complex 1 (TORC). In this study, we found that FER is required to perceive limited nutrient availability caused by low temperature. FER interacts with and activates TORC downstream components to trigger RH growth. In addition, the small GTPase Rho-related protein from plants 2 (ROP2) is also involved in this RH growth response linking FER and TOR. We also found that limited nitrogen nutrient availability can mimic the RH growth response at 10{degrees}C in a NRT1.1-dependent manner. These results uncover a molecular mechanism by which a central hub composed by FER-ROP2-TORC is involved in the control of RH elongation under low temperature and nitrogen deficiency.

plant biology↗

bioRxiv2020

Multistage feedback driven compartmental dynamics of hematopoiesis

Human hematopoiesis is surprisingly resilient to disruptions, providing suitable responses to severe bleeding, long lasting immune activation, and even bone marrow transplants. Still, many blood disorders exist which push the system past its natural plasticity, resulting in abnormalities in the circulating blood. While proper treatment of such diseases can benefit from understanding the underlying cell dynamics, these are non-trivial to predict due to the hematopoietic systems hierarchical nature and complex feedback networks. To characterize the dynamics following different types of perturbations we investigate a model representing hematopoiesis as a sequence of compartments covering all maturation stages - from stem to mature cells - where feedback regulates cell production to ongoing necessities. We find that a stable response to perturbations requires the simultaneous adaptation of cell differentiation and self-renewal rates, and show that under conditions of continuous disruption - as found in chronic hemolytic states - compartment cell numbers evolve to novel stable states.

systems biology↗