Autoxidation of ascorbate mediates lysine -pyrrolation.

Protein -pyrrolation, which converts lysine residues to -pyrrole-l-lysine (pyrK), is a naturally occurring covalent modification. The pyrrolated proteins have a unique property of binding to DNA-staining agents, such as SYBR Green I (SG), and anti-DNA antibodies, suggesting a physiologically relevant modification that gives rise to DNA mimic protein. These properties of pyrrolated protein are suggested to be associated with innate and autoimmune responses.

Unique B-1 cells specific for both N-pyrrolated proteins and DNA evolve with apolipoprotein E deficiency.

Lysine N-pyrrolation, a posttranslational modification, which converts lysine residues to N-pyrrole-L-lysine, imparts electronegative properties to proteins, causing them to mimic DNA. Apolipoprotein E (apoE) has been identified as a soluble receptor for pyrrolated proteins (pyrP), and accelerated lysine N-pyrrolation has been observed in apoE-deficient (apoE) hyperlipidemic mice. However, the impact of pyrP accumulation consequent to apoE deficiency on the innate immune response remains unclear.

Functional effect of nobiletin as a food-derived allosteric modulator of mouse CRFR2β in skeletal muscle.

Activation of corticotropin-releasing factor receptor 2β (CRFR2β) results in increased skeletal muscle mass and the prevention of muscle atrophy. Using a luciferase reporter assay, we screened 357 functional food factors that activate CRFR2β and, subsequently, confirmed that nobiletin (NBT) increases CRFR2β activity. Additionally, we found that NBT augments the activity of the endogenous peptide ligand urocortin 2 (Ucn2) in a concentration-dependent manner.

Glycolaldehyde is an endogenous source of lysine -pyrrolation.

Lysine -pyrrolation converts lysine residues to -pyrrole-l-lysine (pyrK) in a covalent modification reaction that significantly affects the chemical properties of proteins, causing them to mimic DNA. pyrK in proteins has been detected , indicating that pyrrolation occurs as an endogenous reaction. However, the source of pyrK remains unknown.

Bridging molecules are secreted from the skeletal muscle and potentially regulate muscle differentiation.

Muscle myogenesis is an essential step for muscle development and recovery. During muscle fusion, multiple molecules are thought to be necessary for the formation of normal myotubes. Milk fat globule-EGF factor 8 (MFG-E8) and Gas6 are phosphatidylserine-recognizing bridging molecules that are secreted mainly from immune cells.