Cleavage of the Interleukin-11 receptor induces processing of its C-terminal fragments by the gamma-secretase and the proteasome.

The cytokine Interleukin-11 (IL-11) signals through the membrane-bound IL-11 receptor (IL-11R), which is expressed in a cell-type specific manner. We have recently shown that the metalloprotease ADAM10 can cleave the IL-11R. The liberated soluble IL-11R (sIL-11R) ectodomain can bind its ligand, and the resulting IL-11/sIL-11R complex can activate cells that do not express the IL-11R (trans-signaling). In this study, we show that the remaining C-terminal fragment (CTF1) after ADAM10-mediated cleavage is subsequently cleaved within the membrane by the gamma-secretase complex, and that the resulting shorter CTF2 is further degraded by the proteasome. In contrast to other transmembrane receptors, e.g. Notch, we find no evidence that the IL-11R CTF can translocate into the nucleus to act as a transcription factor, suggesting that regulated intramembrane proteolysis of the IL-11R CTF acts as a mechanism to clear the plasma membrane from remaining protein fragments after cleavage of its ectodomain.