Interleukin-6 trans-signaling regulates glycogen consumption after D-galactosamine-induced liver damage

The cytokine interleukin-6 (IL-6) is important for liver regeneration. IL-6 can stimulate target cells either by binding to the membrane-bound IL-6 receptor (IL-6R) leading to dimerization and activation of gp130 or by binding to a soluble IL-6R that results in an activation of gp130 independently of membrane-bound IL-6R, a process called trans-signaling. We have established a transgenic mouse line, in which only trans-signaling is abrogated whereas signaling via the membrane-bound IL-6R is intact. In the present study we employed this mouse model to ask whether the activity of IL-6 during repair of mild liver damage acts via classic or trans-signaling. We analyzed liver regeneration and showed that intracellular signaling, proliferation, and glycogenolysis are reduced in the transgenic mice and thus are regulated by IL-6 trans-signaling. Taken together our results show that upon liver damage, activation of the gp130 pathway depends on the sIL-6R.