title: Biological activity and in vivo half-life of pro-activin A in male rats.
abstract: Mature TGF-β proteins are used in vivo to promote bone growth, combat obesity, reverse fibrosis and pulmonary arterial hypertension, and as potential rejuvenation factors. However, the serum half-life of this family of growth factors is short (∼5 min), limiting their therapeutic potential. Because TGF-β proteins are normally secreted from cells with their prodomains attached, we considered whether these molecules could extend the in vivo half-life and activity of their respective growth factors. Using activin A as a model ligand, we initially modified the cleavage site between the pro- and mature domains to ensure complete processing of the activin A precursor. Co-immunoprecipitation studies confirmed mature activin A is secreted from cells in a non-covalent complex with its prodomain, however, the affinity of this interaction is not sufficient to suppress activin A in vitro biological activity. The plasma clearance profiles of purified pro- and mature activin A were determined over a 4 h period in adult male rats. Both activin forms demonstrated a two-phase decay, with the half-life of pro-activin A (t1/2 fast = 12.5 min, slow = 31.0 min) being greater than that of mature activin A (t1/2 fast = 5.5 min, slow = 20.3 min). Both pro- and mature activin A induced significant increases in serum follicle stimulating hormone levels after 4 h, but no differences were observed in the relative in vivo bioactivities of the two activin isoforms. Increased serum half-life of activin A in the presence of its prodomain identifies a new means to increase the therapeutic effectiveness of TGF-β proteins.
authors.affiliation: Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
authors.forename: Katharine E
authors.initials: KE
authors.lastname: Johnson
authors.affiliation: Hudson Institute of Medical Research, Clayton, VIC 3168, Australia.
authors.forename: Yogeshwar
authors.initials: Y
authors.lastname: Makanji
authors.affiliation: Department of Obstetrics and Gynaecology, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Temple-Smith
authors.affiliation: Hudson Institute of Medical Research, Clayton, VIC 3168, Australia.
authors.forename: Emily K
authors.initials: EK
authors.lastname: Kelly
authors.affiliation: Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Barton
authors.affiliation: Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; Department of Molecular and Translational Science, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Sara L
authors.initials: SL
authors.lastname: Al-Musawi
authors.affiliation: Department of Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, Julius-von Sachs Platz 2, Wuerzburg, Germany.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Mueller
authors.affiliation: Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; Department of Molecular and Translational Science, Monash University, Clayton, VIC 3800, Australia.
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Walton
authors.affiliation: Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; Department of Molecular and Translational Science, Monash University, Clayton, VIC 3800, Australia. Electronic address: Craig.Harrison@hudson.org.au.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Harrison
mesh_terms: D000818:Animals; D005640:Follicle Stimulating Hormone / Q000097:blood; D006207:Half-Life; D028322:Inhibin-beta Subunits / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D008958:Models, Molecular; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D051381:Rats; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; D016212:Transforming Growth Factor beta; C103008:inhibin beta A subunit; D005640:Follicle Stimulating Hormone; D028322:Inhibin-beta Subunits
keywords: Activin; Half-life; Prodomain; Transforming growth factor-β superfamily