Thrombopoietin (TPO) is the principal endogenous regulator of platelet production through binding of the TPO receptor c-MPL (myeloproliferative leukemia virus ligand). TPO is produced mainly by the liver and the kidney and stimulates the proliferation and differentiation of megakaryocytes, leading to increased platelet production. Defects in the Tpo‑Tpo R signaling pathway are associated with a variety of platelet disorders. Tpo is also expressed in the brain where it promotes the apoptosis of hypoxia‑sensitized neurons and inhibits neuronal differentiation by blocking NGF induced signaling.
The 332aa Mamu TPO is engineered as an Fc fusion protein, which links TPO to the Fc region with an enterokinase cleavage site. The Fc region included a BiP signal sequence at the N-terminus to facilitate secretion into the culture supernatant.
Recombinant Mamu TPO is expressed in S2 Drosophila Schneider cell line as Fc-EK-TPO. The protein is purified on protein-A affinity resin; and the Fc-EK site is cleaved with Enterokinase enzyme.
Bioactivity of thrombopoietin is determined through stimulation of proliferation of the megakaryoblast cell line (MO7e cell line).