The invention provides a fusion protein or polypeptide comprising an apelin peptide fused to a multimerizing component. The invention also provides a fusion protein or polypeptide comprising an apelin peptide fused to an Fc domain, a fragment of an Fc domain, or a variant of an Fc domain. Apelin Fc-fusion polypeptides are capable of binding to the apelin receptor (APLNR). Apelin Fc-fusion polypeptides are capable of activating the APLNR and have improved pharmacokinetic properties compared to apelin peptides that are not fused to an Fc or an Fc fragment. Apelin Fc-fusion polypeptides are useful in diseases and conditions related to cardiovascular function, diabetes, cancer, obesity and other apelin-related conditions.
