Involvement of l-afadin, but not s-afadin, in the formation of puncta adherentia junctions of hippocampal synapses.

A hippocampal mossy fiber synapse has a complex structure in which presynaptic boutons attach to the dendritic trunk by puncta adherentia junctions (PAJs) and wrap multiply-branched spines, forming synaptic junctions. It was previously shown that afadin regulates the formation of the PAJs cooperatively with nectin-1, nectin-3, and N-cadherin. Afadin is a nectin-binding protein with two splice variants, l-afadin and s-afadin: l-afadin has an actin filament-binding domain, whereas s-afadin lacks it.

Epithelial membrane protein 1 promotes tumor metastasis by enhancing cell migration via copine-III and Rac1.

Tumor metastasis is the most common cause of cancer death. Elucidation of the mechanism of tumor metastasis is therefore important in the development of novel, effective anti-cancer therapies to reduce cancer mortality. Interaction between cancer cells and surrounding stromal cells in the tumor microenvironment is a key factor in tumor metastasis.

Novel Therapeutic Role for Dipeptidyl Peptidase III in the Treatment of Hypertension.

Dipeptidyl peptidase III (DPP III) cleaves dipeptide residues from the N terminus of polypeptides ranging from 3 to 10 amino acids in length and is implicated in pathophysiological processes through the breakdown of certain oligopeptides or their fragments. In this study, we newly identified the biochemical properties of DPP III for angiotensin II (Ang II), which consists of 8 amino acids. DPP III quickly and effectively digested Ang II with Km = 3.

Significance of serum Zn-α2-glycoprotein for the regulation of blood pressure.

Zn-α2-glycoprotein (ZAG) (molecular weight=41 kDa) is one component in the α2 fraction of human plasma, and is reported to be associated with several diseases, such as cancers and metabolic syndromes. ZAG is also considered to be an important modulator of lipid metabolism. However, little is known about the correlation of serum ZAG levels with indicators of metabolic syndrome.

s-Afadin binds more preferentially to the cell adhesion molecules nectins than l-afadin.

l-Afadin was originally purified from rat brain as an actin filament (F-actin)-binding protein that was homologous to the AF-6 gene product. Concomitantly, s-afadin that did not show an F-actin-binding capability was copurified with l-afadin. Structurally, s-afadin lacks the C-terminal F-actin-binding domain but has two short sequences that were not present in l-afadin.

Suppression of the TGF-β1-induced protein expression of SNAI1 and N-cadherin by miR-199a.

MicroRNA miR-199a is clustered with miR-214 on chromosome 1 and its expression is up-regulated by various factors that are associated with epithelial-to-mesenchymal transition (EMT), such as a transcriptional repressor Twist1 and transforming growth factor (TGF)-β. miR-199a is either up-regulated or down-regulated in a variety of cancers, although EMT is associated with the progression of cancer. We found here that miR-199a suppressed the translation of SNAI1, a transcriptional repressor that plays a role in EMT, by targeting the sequence within the 3'UTR of the SNAI1 mRNA, and reduced the protein level of SNAI1.

Nectin and junctional adhesion molecule are critical cell adhesion molecules for the apico-basal alignment of adherens and tight junctions in epithelial cells.

Tight junctions (TJs) and adherens junctions (AJs) form an apical junctional complex at the apical side of the lateral membranes of epithelial cells, in which TJs are aligned at the apical side of AJs. Many cell adhesion molecules (CAMs) and cell polarity molecules (CPMs) cooperatively regulate the formation of the apical junctional complex, but the mechanism for the alignment of TJs at the apical side of AJs is not fully understood. We developed a cellular system with which epithelial-like TJs and AJs were reconstituted in fibroblasts and analyzed the cooperative roles of CAMs and CPMs.

Interaction of Necl-4/CADM4 with ErbB3 and integrin α6 β4 and inhibition of ErbB2/ErbB3 signaling and hemidesmosome disassembly.

Nectin-like molecule 4 (Necl-4)/CADM4, a transmembrane cell-cell adhesion molecule with three Ig-like domains, was shown to serve as a tumor suppressor, but its mode of action has not been elucidated. In this study, we showed that Necl-4 interacted in cis with ErbB3 through their extracellular regions, recruited PTPN13 and inhibited the heregulin-induced activation of the ErbB2/ErbB3 signaling. In addition, we extended our previous finding that Necl-4 interacts in cis with integrin α6 β4 through their extracellular regions and found that Necl-4 inhibited the phorbol ester-induced disassembly of hemidesmosomes.

Role of scaffold protein afadin dilute domain-interacting protein (ADIP) in platelet-derived growth factor-induced cell movement by activating Rac protein through Vav2 protein.

Cell movement is an important cellular function not only in physiological but also in pathological conditions. Although numerous studies have been conducted to reveal the mechanism of cell movement, the full picture has yet to be depicted, likely due to the complex features of cell movement. We show here that the scaffold protein afadin dilute domain-interacting protein (ADIP), an afadin-binding protein, is involved in the regulation of cell movement.

Cooperative role of nectin-nectin and nectin-afadin interactions in formation of nectin-based cell-cell adhesion.

The nectin cell adhesion molecules interact in trans with each other through their extracellular regions and with afadin through their cytoplasmic tails, forming adherens junctions in cooperation with cadherins. In a single cell, Necl-5 (nectin-like molecule-5) localizes at the leading edge and regulates directional cell movement in response to a chemoattractant. In such a single cell, afadin also localizes at the leading edge without interacting with nectins or Necl-5.

Nebulin and N-WASP cooperate to cause IGF-1-induced sarcomeric actin filament formation.

Insulin-like growth factor 1 (IGF-1) induces skeletal muscle maturation and enlargement (hypertrophy). These responses require protein synthesis and myofibril formation (myofibrillogenesis). However, the signaling mechanisms of myofibrillogenesis remain obscure.

Molecular dissection of the mechanisms of substrate recognition and F-actin-mediated activation of cofilin-phosphatase Slingshot-1.

Slingshot-1 (SSH1), a member of a dual-specificity protein phosphatase family, regulates actin dynamics by dephosphorylating and reactivating cofilin, an actin-depolymerizing factor. SSH1 has the SSH family-specific, N-terminal, noncatalytic (SSH-N) domain, consisting of the A and B subdomains. SSH1 is activated by binding to actin filaments.

Critical roles of actin-interacting protein 1 in cytokinesis and chemotactic migration of mammalian cells.

Cofilin regulates actin filament dynamics by stimulating actin filament disassembly and plays a critical role in cytokinesis and chemotactic migration. Aip1 (actin-interacting protein 1), also called WDR1 (WD-repeat protein 1), is a highly conserved WD-repeat protein in eukaryotes and promotes cofilin-mediated actin filament disassembly in vitro; however, little is known about the mechanisms by which Aip1 functions in cytokinesis and cell migration in mammalian cells. In the present study, we investigated the roles of Aip1 in cytokinesis and chemotactic migration of human cells by silencing the expression of Aip1 using siRNA (small interfering RNA).

Actin filaments-stabilizing and -bundling activities of cofilin-phosphatase Slingshot-1.

Slingshot-1 (SSH1) is known to regulate actin filament dynamics by dephosphorylating and activating cofilin, an actin-depolymerizing factor. SSH1 binds to filamentous (F-) actin through its multiple F-actin-binding sites and its cofilin-phosphatase activity is enhanced by binding to F-actin. In this study, we demonstrate that SSH1 has F-actin-stabilizing and -bundling activities.

Cofilin promotes stimulus-induced lamellipodium formation by generating an abundant supply of actin monomers.

Cofilin stimulates actin filament disassembly and accelerates actin filament turnover. Cofilin is also involved in stimulus-induced actin filament assembly during lamellipodium formation. However, it is not clear whether this occurs by replenishing the actin monomer pool, through filament disassembly, or by creating free barbed ends, through its severing activity.

WICH, a novel verprolin homology domain-containing protein that functions cooperatively with N-WASP in actin-microspike formation.

We describe a novel protein that contains a verprolin-homology (V) region, through which several actin-regulating proteins, including Wiskott-Aldrich syndrome protein (WASP) family members, bind directly to actin. The amino acid sequence is homologous to the sequences of WASP-interacting protein (WIP) and CR16, both of which associate with WASP and/or N-WASP, and thus these three proteins constitute a new protein family. We named the protein WICH (WIP- and CR16-homologous protein).