The immune system is built to protect the body, but new research from The Jackson Laboratory (JAX) suggests that it can also get in the way when it tries to rebuild and heal damaged tissue.

How does a crowded tissue make room every time one cell becomes two? Researchers at the Stowers Institute used live imaging of intestinal organoids to watch the process in real time and discovered that cell division does more than create new cells. The dramatic shape changes of mitosis actively rearrange neighboring cells, helping growing tissues preserve their architecture as they expand. The findings offer a new way to think about how tissues build, repair and maintain themselves, and what may change when that organization breaks down in disease.

Researchers from Capital Medical University, Beijing, China, have identified a CaN/NFATC3/Id3/E2A/Bmp4 signaling pathway that helps explain how low-intensity pulsed ultrasound (LIPUS) promotes bone regeneration. Id3 was identified as a molecular “brake” that limits LIPUS-induced osteogenesis and was significantly downregulated following ultrasound stimulation. The researchers developed an Id3 inhibitory peptide, rID3, which, when combined with LIPUS, enhanced osteogenesis and bone-defect healing in mice, suggesting a potential strategy for improving ultrasound-based bone regeneration.

Even a local mRNA injection can produce unwanted expression in the liver. Researchers have redesigned the lipid nanoparticles that carry mRNA to reduce this spillover in mice while preserving expression in injected muscle. The formulation also supports repeated dosing and improves the confinement of expression after local brain and eye delivery.

Only four enzymes including D-apionate oxidoisomerase (ApnO) are known to catalyze distinct, sequential chemical reactions at a single active site. Biochemical and crystallographic analysis revealed the catalytic mechanism of ApnO containing zinc and manganese ions as metal cofactors, and unique tetrahedral coordination geometry of the later. This study provides new insight into the molecular evolution of rare enzymes that defy the general paradigm wherein a single enzyme's activity is classified under a single reaction mode.