Circadian rhythm and immunity: decoding chrono-immunology using the model organism .

Circadian rhythms are important cellular pathways first described for their essential role in helping organisms adjust to the 24 h day-night cycle and synchronize physiological and behavioral functions. Most organisms have evolved a circadian central clock to anticipate daily environmental changes in light, temperature, and mate availability. It is now understood that multiple clocks exist in organisms to regulate the functions of specific organs.

Alterations in ether phospholipids metabolism activate the conserved UPR-Xbp1- PDIA3/ERp60 signaling to maintain intestinal homeostasis.

Intestinal epithelium regeneration and homeostasis must be tightly regulated. Alteration of epithelial homeostasis is a major contributing factor to diseases such as colorectal cancer and inflammatory bowel diseases. Many pathways involved in epithelial regeneration have been identified, but more regulators remain undiscovered.

Modulation of the cell membrane lipid milieu by peroxisomal β-oxidation induces Rho1 signaling to trigger inflammatory responses.

Phagocytosis, signal transduction, and inflammatory responses require changes in lipid metabolism. Peroxisomes have key roles in fatty acid homeostasis and in regulating immune function. We find that Drosophila macrophages lacking peroxisomes have perturbed lipid profiles, which reduce host survival after infection.

Knockdown of PEX16 Induces Autophagic Degradation of Peroxisomes.

Peroxisome abundance is regulated by homeostasis between the peroxisomal biogenesis and degradation processes. Peroxin 16 (PEX16) is a peroxisomal protein involved in trafficking membrane proteins for de novo peroxisome biogenesis. The present study demonstrates that PEX16 also modulates peroxisome abundance through pexophagic degradation.

Pharmacological inhibition of catalase induces peroxisome leakage and suppression of LPS induced inflammatory response in Raw 264.7 cell.

Peroxisomes are metabolically active organelles which are known to exert anti-inflammatory effects especially associated with the synthesis of mediators of inflammation resolution. However, the role of catalase and effects of peroxisome derived reactive oxygen species (ROS) caused by lipid peroxidation through 4-hydroxy-2-nonenal (4-HNE) on lipopolysaccharide (LPS) mediated inflammatory pathway are largely unknown. Here, we show that inhibition of catalase by 3-aminotriazole (3-AT) results in the generation of peroxisomal ROS, which contribute to leaky peroxisomes in RAW264.

Dimethyloxaloylglycine induces pexophagy in a HIF-2α dependent manner involving autophagy receptor p62.

Peroxisomes are metabolically active oxygen demanding organelles with a high abundance of oxidases making it vulnerable to low oxygen levels such as hypoxic conditions. However, the exact mechanism of peroxisome degradation in hypoxic condition remains elusive. In order to study the mechanism of peroxisome degradation in hypoxic condition, we use Dimethyloxaloylglycine (DMOG), a cell-permeable prolyl-4-hydroxylase inhibitor, which mimics hypoxic condition by stabilizing hypoxia-inducible factors.