Systemic inflammation attenuates the repair of damaged brains through reduced phagocytic activity of monocytes infiltrating the brain.

In this study, we examined how systemic inflammation affects repair of brain injury. To this end, we created a brain-injury model by stereotaxic injection of ATP, a damage-associated molecular pattern component, into the striatum of mice. Systemic inflammation was induced by intraperitoneal injection of lipopolysaccharide (LPS-ip). An analysis of magnetic resonance images showed that LPS-ip reduced the initial brain injury but slowed injury repair. An immunostaining analysis using the neuronal marker, NeuN, showed that LPS-ip delayed removal of dead/dying neurons, despite the fact that LPS-ip enhanced infiltration of monocytes, which serve to phagocytize dead cells/debris. Notably, infiltrating monocytes showed a widely scattered distribution. Bulk RNAseq analyses showed that LPS-ip decreased expression of genes associated with phagocytosis, with PCR and immunostaining of injured brains confirming reduced levels of Cd68 and Clec7a, markers of phagocytic activity, in monocytes. Collectively, these results suggest that systemic inflammation affects properties of blood monocytes as well as brain cells, resulting in delay in clearing damaged cells and activating repair processes.

Photosynthetic artificial organelles sustain and control ATP-dependent reactions in a protocellular system.

Inside cells, complex metabolic reactions are distributed across the modular compartments of organelles. Reactions in organelles have been recapitulated in vitro by reconstituting functional protein machineries into membrane systems. However, maintaining and controlling these reactions is challenging. Here we designed, built, and tested a switchable, light-harvesting organelle that provides both a sustainable energy source and a means of directing intravesicular reactions. An ATP (ATP) synthase and two photoconverters (plant-derived photosystem II and bacteria-derived proteorhodopsin) enable ATP synthesis. Independent optical activation of the two photoconverters allows dynamic control of ATP synthesis: red light facilitates and green light impedes ATP synthesis. We encapsulated the photosynthetic organelles in a giant vesicle to form a protocellular system and demonstrated optical control of two ATP-dependent reactions, carbon fixation and actin polymerization, with the latter altering outer vesicle morphology. Switchable photosynthetic organelles may enable the development of biomimetic vesicle systems with regulatory networks that exhibit homeostasis and complex cellular behaviors.

ATP regeneration system using E. coli ATP synthase and Gloeobacter rhodopsin and its stability.

Great efforts in using non-photosynthetic bacteria as light-utilizing bacteria for producing biomaterials have been developed recently as increasing interest in renewable resources such as light energy. With respect to producing bio-materials industrially such as food ingredients and amino acids, huge amount of adenosine-5'-triphosphate (ATP) is required. In this work, we developed a bio-ATP-synthesis system using ATP synthase of Escherichia coil as a biocatalyst and a microbial rhodopsin which is from primitive cyanobacteria, Gloeobacter violaceus. Gloeobacter rhodopsin (GR) is a light-driven proton pump. Besides electro-chemical gradient produced by cellular respiration system, GR produces a proton gradient using light illumination which is used in additional driving force of synthesizing ATP by ATP synthase. Inverted membrane vesicle was prepared so that it could be incorporated with both of GR and ATP synthase and produced ATP in the exterior side of the vesicle in the presence of light. Since inverted membrane vesicle does not contain precursors for ATP, we added ADP and inorganic phosphate (P(i)). Then, we measured the amounts of ATP produced by ATP synthase in the presence of light. As the average value of 6 samples, 4.79 x 10(-2) micromole of ATP produced for 1 microg of GR per minute. Also, we measured again after 7 days and 65 days, respectively, in order to check the stability of the bio-ATP-synthesis system. Amount of ATP produced decayed double-exponentially and an expected value of half-life of the system was 1.5 days and 39.7 days. Our results demonstrate that ATP was regenerated successfully by using GR and ATP synthase. However, the stability of ATP synthase should be increased to use this system industrially in the near future.