Type I cadherin cell-adhesion proteins are similar in sequence and structure and yet are different enough to mediate highly specific cell-cell recognition phenomena. It has previously been shown that small differences in the homophilic and heterophilic binding affinities of different type I family members can account for the differential cell-sorting behavior. Here we use a combination of X-ray crystallography, analytical ultracentrifugation, surface plasmon resonance and double electron-electron resonance (DEER) electron paramagnetic resonance spectroscopy to identify the molecular determinants of type I cadherin dimerization affinities. Small changes in sequence are found to produce subtle structural and dynamical changes that impact relative affinities, in part via electrostatic and hydrophobic interactions, and in part through entropic effects because of increased conformational heterogeneity in the bound states as revealed by DEER distance mapping in the dimers. These findings highlight the remarkable ability of evolution to exploit a wide range of molecular properties to produce closely related members of the same protein family that have affinity differences finely tuned to mediate their biological roles.cadherin dimerization | protein family design | entropy contribution I n metazoans, the elaboration and maintenance of multicellular architectures relies upon the ability of cells to specifically adhere to one another. Cadherins constitute a superfamily of singlepass transmembrane proteins that can confer such specific adhesive properties to cells (1). In particular, the classical type I and type II cadherins, which are only found in vertebrates and are characterized by an extracellular region comprised of five extracellular cadherin (EC) domains, have been shown to help drive cell-patterning behavior in numerous settings: for example, in morphogenesis (2-4) and in neural patterning (5, 6). Cells expressing the same classical cadherin on their surface generally aggregate through homophilic interactions, whereas cells expressing different cadherins segregate into distinct layers that, in at least some instances, remain in contact with each other through heterophilic binding (7-9).Cell adhesion by classic cadherins is mediated by the dimerization of cadherin extracellular domains emanating from apposed cell surfaces through an interface confined to the N-terminal EC1 domain (Fig. 1A). Numerous crystal structures have revealed the atomic details of the trans (i.e., between cells) dimerization interface for three type I cadherins: C-, E-, and N-cadherins (10-13). In all three cases, the dimer partner molecules swap their N-terminal β-strand (the A*-strand), whose conserved Trp2 residues provide an "anchor" for the adhesive interface by docking into a complementary hydrophobic pocket in the partner protomer (Fig. 1A). A second dimerization interface that can form in the trans orientation has been observed in crystal structures of mutants of both type I and type II classical cadherins. Specifically, numerous mu...

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The lipophilic iminosugar N-[5-(adamantan-1-ylmethoxy)pentyl]-1-deoxynojirimycin (2, AMP-DNM) potently controls hyperglycemia in obese rodent models of insulin resistance. The reduction of visceral glycosphingolipids by 2 is thought to underlie its beneficial action. It cannot, however, be excluded that concomitant inhibition of intestinal glycosidases and associated buffering of carbohydrate assimilation add to this. To firmly establish the mode of action of 2, we developed a panel of lipophilic iminosugars varying in configuration at C-4/C-5 and N-substitution of the iminosugar. From these we identified the l-ido derivative of 2, l-ido-AMP-DNM (4), as a selective inhibitor of glycosphingolipid synthesis. Compound 4 lowered visceral glycosphingolipids in ob/ob mice and ZDF rats on a par with 2. In contrast to 2, 4 did not inhibit sucrase activity or sucrose assimilation. Treatment with 4 was significantly less effective in reducing blood glucose and HbA1c. We conclude that the combination of reduction of glycosphingolipids in tissue and buffering of carbohydrate assimilation by 2 produces a superior glucose homeostasis.

Although T cell checkpoint inhibitors have transformed the treatment of cancer, the molecular determinants of tumor cell sensitivity to T cell–mediated killing need further elucidation. Here, we describe a mouse genome–scale CRISPR knockout screen that identifies tumor cell TNFα signaling as an important component of T cell–induced apoptosis, with NF-κB signaling and autophagy as major protective mechanisms. Knockout of individual autophagy genes sensitized tumor cells to killing by T cells that were activated via specific TCR or by a CD3 bispecific antibody. Conversely, inhibition of mTOR signaling, which results in increased autophagic activity, protected tumor cells from T cell killing. Autophagy functions at a relatively early step in the TNFα signaling pathway, limiting FADD-dependent caspase-8 activation. Genetic inactivation of tumor cell autophagy enhanced the efficacy of immune checkpoint blockade in mouse tumor models. Thus, targeting the protective autophagy pathway might sensitize tumors to T cell–engaging immunotherapies in the clinic.

This paper reviews a particular form of pulsed‐laser‐based thin‐film crystallization method referred to as controlled super‐lateral growth (C‐SLG). By systematically manipulating and controlling the locations, shapes, and extent of melting induced by the incident laser pulses, the C‐SLG approach — notably in a version referred to as sequential lateral solidification (SLS) — can lead to realization of a variety of microstructurally designed crystalline Si films with low structural defect densities, including 1. large‐grained and grain‐boundary‐location controlled polycrystalline films, 2. directionally solidified microstructures, or 3. location‐controlled single‐crystal regions.

Although environment-sensitive prodrug-based nanoparticles (NPs) have developed rapidly, lots of prodrug NPs still show poor selectivity and efficiency of parent drug bioactivation because of tumor heterogeneity. Herein, self-strengthened bioactivating prodrug-based NPs are fabricated via co-encapsulation of oxidation-responsive thioether-linked linoleic acidpaclitaxel conjugates (PTX-S-LA) and β-lapachone (LPC) into polymeric micelles (PMs). Following cellular uptake, PMs first release LPC to significantly elevate the reactive oxidative species (ROS) level through NAD(P)H: quinone oxidoreductase-1 (NQO1) catalysis. Then, NQO1-generated ROS in combination with endogenous high ROS levels in tumor cells could synergistically facilitate PTX-S-LA to release the active cytotoxic agent PTX. Such a novel prodrug nanosystem exhibits selfstrengthened prodrug bioactivation, ultraselective release, and cytotoxicity between cancer and normal cells, prolonged circulation time, and enhanced tumor accumulation, leading to high antitumor efficiency and superior biosafety. Our findings pave the new way for the rational design of oxidation-responsive prodrug NPs for high-efficacy cancer chemotherapy.

Background: AZD4547, a small-molecule inhibitor targeting the tyrosine kinase of Fibroblast Growth Factor Receptors (FGFRs), is currently under phase II clinical study for human subjects having breast cancer, while the underlying mechanism remains elusive. The aim of this study is to explore the potential mechanism by which AZD4547 inhibits breast tumor lung metastases at the level of the tumor microenvironment. Methods: First, through in vitro experiments, we investigated the efficacy of the FGFRs inhibitor AZD4547 on 4T1 tumor cells for their proliferation, apoptosis, migration, and invasion. Second, by in vivo animal experiments, we evaluated the effects of AZD4547 on tumor growth and lung metastases in 4T1 tumor-bearing mice. Finally, we examined the impact of AZD4547 on the infiltration of myeloid-derived suppressor cells (MDSCs) in lung, spleens, peripheral blood and tumor. Results: Through this study we found that AZD4547 could efficiently suppress tumor 4T1 cells through restraining their proliferation, blocking migration and invasion, and inducing apoptosis in vitro. In animal model we also demonstrated that AZD4547 was able to inhibit tumor growth and lung metastases, consistent with the decreased MDSCs accumulation in the tumor and lung tissues, respectively. Moreover, the reduced number of MDSCs in peripheral blood and spleens were also observed in the AZD4547-treated mice. Importantly, through the AZD4547 treatment, the CD4⁺ and CD8⁺ T-cells were significantly increased in tumor and spleens. Conclusion: Our studies showed that AZD4547 can inhibit breast cancer cell proliferation, induce its apoptosis and block migration and invasion in vitro and suppress tumor growth and lung metastases by modulating the tumor immunologic microenvironment in vivo.