PURIFICATION AND CHARACTERIZATION OF NOVEL HEPARIN-BINDING GROWTH-FACTORS IN UTERINE SECRETORY FLUIDS - IDENTIFICATION AS HEPARIN-REGULATEDM-R-10,000 FORMS OF CONNECTIVE-TISSUE GROWTH-FACTOR

Uterine growth factors are potential effector molecules in embryo grow th signaling pathways. Pig uterine luminal flushings contained a hepar in-binding growth factor (HBGF) that required 0.8 M NaCl for elution f rom heparin columns and was termed HBGF-0.8, This factor, which was he at- and acid-labile and of M-r 10,000 as assessed by gel filtration, s timulated DNA synthesis in fibroblasts and smooth muscle cells but not endothelial cells. Two forms of HBGF-0.8, termed HBGF-0.8-P1 and HBGF -0.8-P2, exhibited differential heparin-binding properties. SDS-polyac rylamide gel electrophoresis showed that each form of HBGF-0.8 migrate d with an apparent M-r of 10,000 under reducing conditions, Amino acid sequencing revealed the N-terminal sequence EENIKKGKKXIRTPKI for HBGF -0.8-P1 and EENIKKGKKXIRT for HBGF-0.8-P2. These sequences corresponde d, respectively, to residues 247-262 and 248-259 of the 349-residue pr edicted primary translation product of porcine connective tissue growt h factor (pCTGF). 10-kDa CTGF-mediated fibroblast DNA synthesis was mo dulated by exogenous heparin, and CTGF-immunoreactive proteins of 10, 16, and 20 kDa were present in unfractionated uterine luminal flushing s. These data reveal the identity of a novel growth factor in uterine fluids as a highly truncated form of CTGF and show that the N-terminal two-thirds of the CTGF primary translation product is not required fo r mitogenic activity or heparin binding.