Actin interacting protein 1 (Aip1) is a conserved component of the actin cytoskeleton first identified in a two-hybrid screen against yeast actin. Here, we report that Aip1p also interacts with the ubiquitous actin depolymerizing factor cofilin. A two-hybrid–based approach using cofilin and actin mutants identified residues necessary for the interaction of actin, cofilin, and Aip1p in an apparent ternary complex. Deletion of the AIP1 gene is lethal in combination with cofilin mutants or act1-159, an actin mutation that slows the rate of actin filament disassembly in vivo. Aip1p localizes to cortical actin patches in yeast cells, and this localization is disrupted by specific actin and cofilin mutations. Further, Aip1p is required to restrict cofilin localization to cortical patches. Finally, biochemical analyses show that Aip1p causes net depolymerization of actin filaments only in the presence of cofilin and that cofilin enhances binding of Aip1p to actin filaments. We conclude that Aip1p is a cofilin-associated protein that enhances the filament disassembly activity of cofilin and restricts cofilin localization to cortical actin patches.

Interleukin (IL)-17A exists as a homodimer (A/A) or as a heterodimer (A/F) with IL-17F. IL-17A is expressed by a subset of T-cells, called Th17 cells, at inflammatory sites. Most cell types can respond to the local production of IL-17A because of the near ubiquitous expression of IL-17A receptors, IL-17RA and IL-17RC. IL-17A stimulates the release of cytokines and chemokines designed to recruit and activate both neutrophils and memory T-cells to the site of injury or inflammation and maintain a proinflammatory state. IL-17A-producing pathogenic T-cells contribute to the pathogenesis of autoimmune diseases, including psoriasis, psoriatic arthritis, rheumatoid arthritis, and ankylosing spondylitis. This study describes the generation and characterization of ixekizumab, a humanized IgG4 variant IL-17A-neutralizing antibody. Ixekizumab binds human and cynomolgus monkey IL-17A with high affinity and binds rabbit IL-17A weakly but does not bind to rodent IL-17A or other IL-17 family members. Ixekizumab effectively inhibits the interaction between IL-17A and its receptor in binding assays and potently blocks IL-17A-induced GRO or KC secretion in cell-based assays. In an in vivo mouse pharmcodynamic model, ixekizumab blocks human IL-17A-induced mouse KC secretion. These data provide a comprehensive preclinical characterization of ixekizumab, for which the efficacy and safety have been demonstrated in human clinical trials in psoriasis and psoriatic arthritis.

Purpose: MET, the receptor for hepatocyte growth factor (HGF), has been implicated in driving tumor proliferation and metastasis. High MET expression is correlated with poor prognosis in multiple cancers. Activation of MET can be induced either by HGF-independent mechanisms such as gene amplification, specific genetic mutations, and transcriptional upregulation or by HGF-dependent autocrine or paracrine mechanisms.Experimental Design/Results: Here, we report on LY2875358, a novel humanized bivalent anti-MET antibody that has high neutralization and internalization activities, resulting in inhibition of both HGFdependent and HGF-independent MET pathway activation and tumor growth. In contrast to other bivalent MET antibodies, LY2875358 exhibits no functional agonist activity and does not stimulate biologic activities such as cell proliferation, scattering, invasion, tubulogenesis, or apoptosis protection in various HGFresponsive cells and no evidence of inducing proliferation in vivo in a monkey toxicity study. LY2875358 blocks HGF binding to MET and HGF-induced MET phosphorylation and cell proliferation. In contrast to the humanized one-armed 5D5 anti-MET antibody, LY2875358 induces internalization and degradation of MET that inhibits cell proliferation and tumor growth in models where MET is constitutively activated. Moreover, LY2875358 has potent antitumor activity in both HGF-dependent and HGF-independent (METamplified) xenograft tumor models. Together, these findings indicate that the mechanism of action of LY2875358 is different from that of the one-armed MET antibody.Conclusions: LY2875358 may provide a promising therapeutic strategy for patients whose tumors are driven by both HGF-dependent and HGF-independent MET activation. LY2875358 is currently being investigated in multiple clinical studies. Clin Cancer Res; 20(23); 6059-70. Ó2014 AACR.

In a search for novel growth factors, we discovered that human interleukin-20 (IL-20) enhanced colony formation by CD34 ؉ multipotential progenitors. IL-20 had no effect on erythroid, granulocyte-macrophage, or megakaryocyte progenitors. IL- IntroductionCytokines are important regulators of the growth and development of hematopoietic cells 1,2 ; some are currently in clinical use. In a search for novel factors that regulate hematopoiesis, colony assays were used to screen novel secreted proteins identified through bioinformatics. One protein identified was identical to . 3,4 We demonstrate that IL-20 specifically enhances the proliferation of multipotential progenitors in vitro and in vivo without effect on more lineage-restricted progenitor cells. Study design Protein productionRecombinant human , containing a C-terminal FLAG tag (Eastman Kodak, Rochester, NY) followed by 6 histidine residues (Flis), was produced in 293EBNA1 cells. 5 We captured rhIL-20-Flis on Pharmacia Chelating Sepharose FF (Amersham-Pharmacia, Piscataway, NJ). The endotoxin level was less than 5.3 EU/mg rhIL-20. Colony assays for human and murine progenitorsCD34 ϩ human bone marrow or cord blood cells were purchased from BioWhittaker (Walkersville, MD). Colony assays for granulocytemacrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitors were as described. 6,7 Megakaryocyte (CFU-Meg) progenitor assays were carried out using MegaCult-C medium (Stem Cell Technologies, Vancouver, BC, Canada). IL-20 transgenic miceTransgenic (TG) mice were generated by established techniques. 8 Human IL-20 was overexpressed in TG mice using apolipoprotein E gene promoter. IL-20 levels in mouse serum were determined using enzyme-linked immunosorbent assay (ELISA) with antihuman rhIL-20. rhIL-20 administration to normal miceFemale BDF1 mice (8-10 weeks of age; Harlan, Indianapolis, IN) were administered rhIL-20 (5 g/mouse) subcutaneously twice a day for 10 days. At day 11, mice were killed, bone marrow and spleen cells were counted, cells were used for colony assays, and the proportion of progenitors in S-phase of the cell cycle was estimated. 7,9,10 Results and discussion IL-20 in vitroIL-20 did not stimulate colony formation, but it increased the numbers of larger-sized colonies in combination with recombinant human stem cell factor (SCF) and erythropoietin (EPO) ( Figure 1Ai-ii). Colonies cultured with IL-20 contained cells with and without hemoglobin expression. Microscopic examination of 22 individual large colonies stained with Wright-Giemsa revealed mainly erythroblasts mixed with megakaryocytes. Granulocytes and monocytes were also detected (original magnification, ϫ 400) within these colonies but were less prominent than erythroblasts and megakaryocytes . This suggested that IL-20 enhanced CFU-GEMM.Colony assays were performed with human bone marrow (BM) and cord blood (CB) CD34 ϩ cells using various cytokine combinations. IL-20 (200 ng/mL), in combination with EPO and SCF, significantly enhanced BM CFU-GEMM numbers approximate...