Molecular cloning and functional expression of feline thrombopoietin

Feline thrombopoietin (TPO) was molecularly cloned to establish a basis for cytokine therapy of thrombocytopenia in cats. cDNA clones covering the who le coding sequence of feline TPO were isolated from feline liver. The felin e TPO cDNA obtained in this study contained an open reading frame encoding 349 amino acid residues. The predicted amino acid sequence of feline TPO sh ared 78.7, 69.9, 72.9 and 83.0% similarity with sequences of human, murine, rat and canine TPO, respectively. Four cysteine residues and two of four N -glycosylation sites that are conserved among species were also found at th e corresponding positions in feline TPO. The feline TPO cDNA fragment encod ing the whole amino acid coding region was recloned into an expression vect or, and the resulting vector was transfected into 293T cells using the calc ium phosphate method. The supernatant of the transfected 293T cells stimula ted the proliferation of a human megakaryoblastic leukemia cell line (UT-7/ TPO) cells in a dose dependent manner, indicating that the feline TPO cDNA obtained in this study encodes biologically active feline TPO. (C) 1998 Els evier Science B.V. All rights reserved.