Abstract
Angiogenesis, or neovascularization, is tightly orchestrated by endogenous regulators that promote or inhibit the process. The fine-tuning of these pro- and anti-angiogenic elements (the angiogenic balance) helps establish the homeostasis in tissues, and any aberration leads to pathologic conditions. The type I thrombospondin repeats are a family of protein structural elements involved in the control of angiogenesis, and some proteins containing these repeats have been identified as negative regulators of angiogenesis. Here we identify a set of 11 novel, anti-angiogenic 18-20-amino acid peptides that are derived from proteins that belong to the CCN protein family and contain type I thrombospondin motifs. We have named these peptides spondinstatin-1, cyrostatin, connectostatin, nephroblastostatin, wispostatin-2, wispostatin-3, netrinstatin-5C, netrinstatin-5D, adamtsostatin-like-4, fibulostatin-6.1, and complestatin-C6 to reflect their origin. We have shown that these peptides inhibit proliferation and migration of human umbilical vein endothelial cells in vitro. By conducting a clustering analysis of the amino acid sequences using sequence similarity criteria and of the experimental results using a hierarchical clustering algorithm, we have demonstrated that there is an underlying correlation between the sequence and activity of the identified peptides. This combination of experimental and computational approaches introduces a novel systematic framework for studying peptide activity, identifying novel peptides with anti-angiogenic activity, and designing mimetic peptides with tailored properties.