Stress responses across the scales of life: Towards a universal theory of biological stress

Stress sharing as cognitive glue for collective intelligences: A computational model of stress as a coordinator for morphogenesis

Individual cells have numerous competencies in physiological and metabolic spaces. However, multicellular collectives can reliably navigate anatomical morphospace towards much larger, reliable endpoints. Understanding the robustness and control properties of this process is critical for evolutionary developmental biology, bioengineering, and regenerative medicine. One mechanism that has been proposed for enabling individual cells to coordinate toward specific morphological outcomes is the sharing of stress (where stress is a physiological parameter that reflects the current amount of error in the context of a homeostatic loop). Here, we construct and analyze a multiscale agent-based model of morphogenesis in which we quantitatively examine the impact of stress sharing on the ability to reach target morphology. We found that stress sharing improves the morphogenetic efficiency of multicellular collectives; populations with stress sharing reached anatomical targets faster. Moreover, stress sharing influenced the future fate of distant cells in the multi-cellular collective, enhancing cells' movement and their radius of influence, consistent with the hypothesis that stress sharing works to increase cohesiveness of collectives. During development, anatomical goal states could not be inferred from observation of stress states, revealing the limitations of knowledge of goals by an extern observer outside the system itself. Taken together, our analyses support an important role for stress sharing in natural and engineered systems that seek robust large-scale behaviors to emerge from the activity of their competent components.

Glucocorticoid alleviates hypothalamic nerve injury via remodeling HPA axis homeostasis in stressed rats

Excessive stress can exceed the adjustment ability of body and cause injury and dysfunction, while elucidation of the mechanism and prevention measures of stress-related injury are still insufficient. The present study was to observe the effect of glucocorticoid (GC) on stress-induced hypothalamic nerve injury and elucidate the potential mechanism. The present study intended to establish a chronic restraint stress rat model for follow-up study. Open field test and elevated plus maze test were used to observe behavioral changes of stress rats; Enzyme-linked immunosorbent assay (ELISA) was used to detect changes in the levels of hypothalamus-pituitary-adrenal (HPA) axis-related hormones and inflammatory factors in hypothalamus; toluidine blue staining was used to observe pathological changes of hypothalamus. The results showed that stress rats showed obvious anxiety-like behaviors, the levels of HPA axis-related hormones and inflammatory factors showed abnormal fluctuations, and morphological results showed significant nerve injury in hypothalamus. Low-dose GC treatment significantly improved behavioral changes, alleviated hypothalamic nerve injury, and restored hypothalamic levels of inflammatory factors, serum levels of GC, corticotropin-releasing hormone (CRH), and adrenocorticotropic hormone (ACTH) and GC level in adrenal cortex of stressed rats, while GC receptor (GR) inhibitor, CRH receptor inhibitor, and adrenalectomy reversed the ameliorative effects of low-dose GC. Our study clarified that low-dose GC can restore stress coping ability by reshaping the homeostasis of the HPA axis, thus alleviating behavioral abnormalities and hypothalamic nerve injury in stressed rats.

Extracellular pectin-RALF phase separation mediates FERONIA global signaling function

The FERONIA (FER)-LLG1 co-receptor and its peptide ligand RALF regulate myriad processes for plant growth and survival. Focusing on signal-induced cell surface responses, we discovered that intrinsically disordered RALF triggers clustering and endocytosis of its cognate receptors and FER- and LLG1-dependent endocytosis of non-cognate regulators of diverse processes, thus capable of broadly impacting downstream responses. RALF, however, remains extracellular. We demonstrate that RALF binds the cell wall polysaccharide pectin. They phase separate and recruit FER and LLG1 into pectin-RALF-FER-LLG1 condensates to initiate RALF-triggered cell surface responses. We show further that two frequently encountered environmental challenges, elevated salt and temperature, trigger RALF-pectin phase separation, promiscuous receptor clustering and massive endocytosis, and that this process is crucial for recovery from stress-induced growth attenuation. Our results support that RALF-pectin phase separation mediates an exoskeletal mechanism to broadly activate FER-LLG1-dependent cell surface responses to mediate the global role of FER in plant growth and survival.