A novel splice variant of human TGF-β type II receptor encodes a soluble protein and its Fc-tagged version prevents liver fibrosis in vivo

ALEJANDRA CARREA; STELLA MARIS ECHARTE; ALEXANDER MIGUEL MONZÓN; DEWEY, RICARDO A.; MARCELA S. BERTOLIO; ROMO ANA; SABRINA CAMPISANO; TANIA MELINA RODRÍGUEZ; ANABELA LA COLLA; GABRIELA CANZIANI; GERMAN PATRICIO BARLETTA; ANDREA N CHISARI

bioRxiv

Cold Spring Harbor Laboratory

Año: 2021

2692-8205

We describe, for the first time, a new splice variant of the human TGF-β type II receptor(TβRII). The new transcript lacks 149 nucleotides, causing a frameshift withthe appearance of an early stop codon, rendering a truncated mature protein of 57amino acids. The predicted protein, lacking the transmembrane domain and with adistinctive 13 amino acid stretch in the C-terminus, was named TβRII-Soluble Endogenous(TβRII-SE). Binding predictions indicated that the novel 13 amino acidstretch interacts with all three TGF-β cognate ligands and generate a more extensiveprotein-protein interface than TβRII. TβRII-SE and human IgG1 Fc-domain,were fused in frame in a lentiviral vector (Lv) for further characterization. With thisvector, we transduced 293T cells and purified TβRII-SE/Fc by A/G protein chromatographyfrom conditioned medium. Immunoblotting revealed homogeneousbands of approximately 37 kDa (reduced) and 75 kD (non-reduced), indicating thatTβRII-SE/Fc is secreted as a disulphide-linked homodimer. Moreover, high affinitybinding of TβRII-SE to the three TGF-β isoforms was confirmed by Surface PlasmonResonance (SPR) analysis. Also, intrahepatic delivery of Lv.TβRII-SE/Fc in acarbon tetrachloride-induced liver fibrosis model revealed amelioration of liver injuryand fibrosis. Our results indicate that TβRII-SE is a novel member of the TGF-β signaling pathway with distinctive characteristics. This novel protein offers analternative tool for the prevention and treatment of pathologies caused by theoverproduction of TGF-β ligands.