Osmotic Stress Modulates the Balance between Exocytosis and Clathrin-Mediated Endocytosis in Arabidopsis thaliana

The sessile life style of plants creates the need to deal with an often adverse environment, in which water availability can change on a daily basis, challenging the cellular physiology and integrity. Changes in os- motic conditions disrupt the equilibrium of the plasma membrane： hypoosmotic conditions increase and hyperosmotic environment decrease the cell volume. Here, we show that short-term extracellular osmotic treatments are closely followed by a shift in the balance between endocytosis and exocytosis in root mer- istem cells. Acute hyperosmotic treatments （ionic and nonionic） enhance clathrin-mediated endocytosis simultaneously attenuating exocytosis, whereas hypoosmotic treatments have the opposite effects. In addition to clathrin recruitment to the plasma membrane, components of early endocytic trafficking are essential during hyperosmotic stress responses. Consequently, growth of seedlings defective in elements of clathrin or early endocytic machinery is more sensitive to hyperosmotic treatments. We also found that the endocytotic response to a change of osmotic status in the environment is dominant over the presum- ably evolutionary more recent regulatory effect of plant hormones, such as auxin. These results imply that osmotic perturbation influences the balance between endocytosis and exocytosis acting through clathrin- mediated endocytosis. We propose that tension on the plasma membrane determines the addition or removal of membranes at the cell surface, thus preserving cell integrity.

Vacuole Integrity Maintained by DUF300 Proteins Is Required for Brassinosteroid Signaling Regulation

Brassinosteroid （BR） hormone signaling controls multiple processes during plant growth and development and is initiated at the plasma membrane through the receptor kinase BRASSINOSTEROID INSENSITIVE1 （BRI1） together with co-receptors such as BRI1-ASSOClATED RECEPTOR KINASE1 （BAK1）. BRI1 abun- dance is regulated by endosomal recycling and vacuolar targeting, but the role of vacuole-related proteins in BR receptor dynamics and BR responses remains elusive. Here, we show that the absence of two DUF300 domain-containing tonoplast proteins, LAZARUS1 （LAZl） and LAZl HOMOLOG1 （LAZlH1）, causes vacuole morphology defects, growth inhibition, and constitutive activation of BR signaling. Intriguingly, tonoplast accumulation of BAK1 was substantially increased and appeared causally linked to enhanced BRI1 trafficking and degradation in lazl lazlhl plants. Since unrelated vacuole mutants exhibited normal BR responses, our findings indicate that DUF300 proteins play distinct roles in the regulation of BR signaling by maintaining vacuole integrity required to balance subcellular BAK1 pools and BR receptor distribution.

Progress towards using community context with clinical data in primary care

Community-level factors have significant impacts on health.There is renewed enthusiasm for integrating these data with electronic health record(EHR)data for use in primary care to improve health equity in the USA.Thus,it is valuable to reflect on what has been published to date.Specifically,we comment on:(1)recommendations about combining community-level factors in EHRs for use in primary care;(2)examples of how these data have been combined and used;and(3)the impact of using combined data on healthcare,patient health and health equity.We found publications discussing the potential of combined data to inform clinical care,target interventions,track population health and spark community partnerships with the goal of reducing health disparities and improving health equity.Although there is great enthusiasm and potential for using these data to inform primary care,there is little evidence of improved healthcare,patient health or health equity.