Fig. 14

Metrnl is involved in various pharmacological pathways through intracellular signalling between the cells. In nerve cells, it promotes the neurite outgrowth via the JAKSTAT3 and MEK-ERK signalling pathway. In fat cells due to upregulation of the Metrnl increases the lipid metabolism, relieves from the high-fat diet-induced inflammation and improves adipose remodeling through upregulation of PPARγ, due to which the insulin resistance is also improved. In muscle cells or myocytes it increases the PPARγ signalling which increases the phosphorylation of AMPK due to increased intracellular calcium and also encourages the phosphorylation of TBC1D1, HDAC5, and p38 MAPK in an AMPK-mediated manner, then promotes the expression and translocation of GLUT4, which thus improves the insulin sensitivity and reduces the inflammation [103]