Expression of a novel member of the TGF-beta superfamily, growth differentiation factor-15/macrophage-inhibiting cytokine-1 (GDF-15/MIC-1) in adult rat tissues

We have cloned a novel member of the transforming growth factor-P (TGF-P) s uperfamily from a human placental cDNA library. The sequence is identical t o five very recently published sequences, of which only one (macrophage inh ibitory cytokine-l, MIC-1) has been characterized in terms of function. In light of the present data demonstrating the wide distribution of the mRNA a nd putative multifunctionality, we propose to name this molecule growth/dif ferentiation factor-15/MIC-1 (GDF-15/MIC-1). The deduced amino acid sequenc e reveals typical features of a secreted molecule. The epithelium of the ch oroid plexus is the only site in the adult brain expressing detectable leve ls of GDF-15/MIC-1 mRNA. Many epithelia of non-neural tissues including tho se of the prostate and intestinal mucosa, bronchi and bronchioli, secretory tubuli of the submandibular gland, and lactating mammary gland are promine nt sites of GDF-15/MIC-1 synthesis. GDF-15/MIC-1 is also strongly expressed by macrophages in the adrenal gland. Thus, GDF-15/MIC-1, like many other m embers of the TGF-P superfamily, is widely distributed in adult tissues, be ing most strongly expressed in epithelial cells and macrophages.