Zhaocai Zhou

A Peptide Mimicking VGLL4 Function Acts as a YAP Antagonist Therapy against Gastric Cancer

The Hippo pathway has been implicated in suppressing tissue overgrowth and tumor formation by restricting the oncogenic activity of YAP. However, transcriptional regulators that inhibit YAP activity have not been well studied. Here, we uncover clinical importance for VGLL4 in gastric cancer suppression and find that VGLL4 directly competes with YAP for binding TEADs. Importantly, VGLL4s tandem Tondu domains are not only essential but also sufficient for its inhibitory activity toward YAP. A peptide mimicking this function of VGLL4 potently suppressed tumor growth in vitro and in vivo. These findings suggest that disruption of YAP-TEADs interaction by a VGLL4-mimicking peptide may be a promising therapeutic strategy against YAP-driven human cancers.

VGLL4 functions as a new tumor suppressor in lung cancer by negatively regulating the YAP-TEAD transcriptional complex

Lung cancer is one of the most devastating diseases worldwide with high incidence and mortality. Hippo (Hpo) pathway is a conserved regulator of organ size in both Drosophila and mammals. Emerging evidence has suggested the significance of Hpo pathway in cancer development. In this study, we identify VGLL4 as a novel tumor suppressor in lung carcinogenesis through negatively regulating the formation of YAP-TEAD complex, the core component of Hpo pathway. Our data show that VGLL4 is frequently observed to be lowly expressed in both mouse and human lung cancer specimens. Ectopic expression of VGLL4 significantly suppresses the growth of lung cancer cells in vitro. More importantly, VGLL4 significantly inhibits lung cancer progression in de novo mouse model. We further find that VGLL4 inhibits the activity of the YAP-TEAD transcriptional complex. Our data show that VGLL4 directly competes with YAP in binding to TEADs and executes its growth-inhibitory function through two TDU domains. Collectively, our study demonstrates that VGLL4 is a novel tumor suppressor for lung cancer through negatively regulating the YAP-TEAD complex formation and thus the Hpo pathway.

Structure of Sad1-UNC84 Homology (SUN) Domain Defines Features of Molecular Bridge in Nuclear Envelope

Background: The SUN domain mediates mechanical linkage across the nuclear envelope. Results: The structure of the SUN2 protein SUN domain was solved. The structure features important for SUN domain function were identified. Conclusion: The SUN domain forms a homotrimer. The SUN-KASH domain interaction is required for nuclear migration. Significance: The study provides insights into how the SUN protein complex functions. The SUN (Sad1-UNC-84 homology) domain is conserved in a number of nuclear envelope proteins involved in nuclear migration, meiotic telomere tethering, and antiviral responses. The LINC (linker of nucleoskeleton and cytoskeleton) complex, formed by the SUN and the nesprin proteins at the nuclear envelope, serves as a mechanical linkage across the nuclear envelope. Here we report the crystal structure of the SUN2 protein SUN domain, which reveals a homotrimer. The SUN domain is sufficient to mediate binding to the KASH (Klarsicht, ANC-1, and Syne homology) domain of nesprin 2, and the regions involved in the interaction have been identified. Binding of the SUN domain to the KASH domain is abolished by deletion of a region important for trimerization or by point mutations associated with nuclear migration failure. We propose a model of the LINC complex, where the SUN and the KASH domains form a higher ordered oligomeric network in the nuclear envelope. These findings provide the structural basis for understanding the function and the regulation of the LINC complex.

Land use affects the relationship between species diversity and productivity at the local scale in a semi-arid steppe ecosystem

Summary 1 The accelerating extinction rate of plant species and its effect on ecosystem functioning is a hotly debated topic in ecological research. Most research projects concerning the relationship between species diversity and productivity have been conducted in artificial plant communities, with only a few in natural ecosystems. In this study we examined the relationship between species diversity and above‐ground net primary productivity (ANPP) over two consecutive growth seasons (2004 and 2005) in a semi‐arid steppe ecosystem of northern China, that were subjected to different land uses.2 Land use affected the relationship between species diversity and ANPP in this semi‐arid steppe ecosystem. Exclusion of grazing without or with biomass removal by mowing increased ANPP, species richness and species diversity compared with free grazing; the effect was reflected mainly as enhanced importance of the perennial forbs functional group in terms of their relative contributions to ANPP, plant cover and plant abundance.3 Many mechanisms regulate the relationship between species diversity and productivity. Differential effects of anthropogenic activities on biodiversity and ecosystem functioning greatly complicate the analysis of such relationships. On grazing‐exclusion sites the relationship between ANPP and species richness can be best described as an exponential growth function (R 2 = 0·99, P < 0·001, n = 24); whereas on the free‐grazing site the relationship takes the form of exponential decay (R 2 = 0·96, P < 0·001, n = 24). Our study concludes that the mode and severity of disturbance are important factors for interpreting the relationship between species diversity and productivity in semi‐arid steppe ecosystems.

Acid-Activatable Versatile Micelleplexes for PD-L1 Blockade-Enhanced Cancer Photodynamic Immunotherapy

Photodynamic therapy (PDT) has emerged as a promising clinical modality for cancer therapy due to its ability to initiate an antitumor immune response. However, PDT-mediated cancer immunotherapy is severely impaired by tumor-cell immunosuppression of host T cell antitumor activity through the programmed cell death 1 ligand (PD-L1) and programmed cell death receptor 1 (PD-1) (PD-L1-PD-1) immune checkpoint pathway. Here, we demonstrate that PDT-mediated cancer immunotherapy can be augmented by PD-L1 knockdown (KD) in tumor cells. We rationally designed a versatile micelleplex by integrating an acid-activatable cationic micelle, photosensitizer (PS), and small interfering RNA (siRNA). The micelleplex was inert at physiological pH conditions and activated only upon internalization in the acidic endocytic vesicles of tumor cells for fluorescence imaging and PDT. Compared to PDT alone, the combination of PDT and PD-L1 KD showed significantly enhanced efficacy for inhibiting tumor growth and distant metastasis in a B16-F10 melanoma xenograft tumor model. These results suggest that acid-activatable micelleplexes utilizing PDT-induced cancer immunotherapy are more effective when combined with siRNA-mediated PD-L1 blockade. This study could provide a general strategy for enhancing the therapy efficacy of photodynamic cancer therapy.

Histone acetyltransferase mediated regulation of FOXP3 acetylation and Treg function

Regulatory T cells (Tregs) are required for the maintenance of immune homeostasis as first clearly described by Herman Waldmanns laboratory. Dysfunction of Treg cells also leads to fatal autoimmunity in humans and mice. Conversely, the activation of different classes of Tregs operative systemically and within the cancer microenvironment can suppress host anti-tumor immune responses and promote tumor progression. Therefore, the development of new therapeutic approaches to regulate the activity of Treg cells may have considerable clinical potential. FOXP3 is the key transcriptional regulator of Treg development and function. The activity of FOXP3 is regulated by acetylation, a process catalyzed by distinct types of histone/protein acetyltransferases (HATs) that regulate the functions of many transcription factors, independently of FOXP3, as well as non-histone proteins, in addition to their effects on chromatin accessibility. Interactions between FOXP3 and these enzymes determine the suppressive function of FOXP3. Clearly, small molecules targeting these enzymes are candidates for the regulation of Treg function in vaccines and tumor therapies.

Differential binding patterns of monoclonal antibody 2C4 to the ErbB3–p185her2/neu and the EGFR–p185her2/neu complexes

2C4 (Pertuzumab, Omnitarg) is a monoclonal antibody targeting p185her2/neu, which is overexpressed in 30% of invasive breast cancer. 2C4 is currently in phase II clinical trials for several types of cancers. This antibody has been reported to disrupt the association between p185her2/neu and ErbB3. In our studies of epidermal growth factor receptor (EGFR)–p185her2/neu heterodimerization, we noted that 2C4 formed associations with the EGFR–p185her2/neu receptor complex. Our data argue against 2C4 as a universal heterodimerization blocker for p185her2/neu, but indicate that cocktails of monoclonal antibodies binding distinct interaction surfaces of p185her2/neu will emerge as the most potent targeted therapy.

FOXP3 and its partners: structural and biochemical insights into the regulation of FOXP3 activity

Forkhead box protein P3 (FOXP3) contributes to a unique transcriptional signature and serves as a functional marker of CD4+CD25+ natural regulatory T cells. Dysfunction of FOXP3 in human is associated with fatal autoimmune disease known as immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX) or X-linked autoimmunity–allergic disregulation syndrome (XLAAD). FOXP3 also can act as a breast tumor suppressor of the v-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (neuro/glioblastoma derived oncogene homolog (avian)) (Her2/neu) gene. While the suppressive functions of FOXP3 in maintaining the immune balance between tolerance and autoimmunity are obvious, the underlying molecular mechanism remains almost entirely undefined. Recent studies indicate that FOXP3 may form a dynamic superamolecular complex with a variety of molecular partners including transcription factors and enzymatic proteins to regulate transcription. How the FOXP3 ensemble changes in response to T-cell receptor signals and/or proinflammatory signal remains unclear although work from this laboratory has revealed its complexity. Structural information on FOXP3 complex may offer novel functional insights, as well as facilitate the development of rational means to modulate regulatory T-cell function in various human diseases.

Human glucocorticoid-induced TNF receptor ligand regulates its signaling activity through multiple oligomerization states

Ligation between glucocorticoid-induced tumor necrosis factor receptor (GITR) and its ligand (GITRL) provides an undefined signal that renders CD4+CD25− effector T cells resistant to the inhibitory effects of CD4+CD25+ regulatory T cells. To understand the structural basis of GITRL function, we have expressed and purified the extracellular domain of human GITR ligand in Escherichia coli. Chromotography and cross-linking studies indicate that human GITRL (hGITRL) exists as dimers and trimers in solution and also can form a supercluster. To gain insight into the nature of GITRL oligomerization, we determined the crystallographic structures of hGITRL, which revealed a loosely associated open trimer with a deep cavity at the molecular center and a flexible C-terminal tail bent for trimerization. Moreover, a tetramer of trimers (i.e., supercluster) has also been observed in the crystal, consistent with the cross-linking analysis. Deletion of the C-terminal distal three residues disrupts the loosely assembled trimer and favors the formation of a dimer that has compromised receptor binding and signaling activity. Collectively, our studies identify multiple oligomeric species of hGITRL that possess distinct kinetics of ERK activation. The studies address the functional implications and structural models for a process by which hGITRL utilizes multiple oligomerization states to regulate GITR-mediated signaling during T cell costimulation.

Par-1 Regulates Tissue Growth by Influencing Hippo Phosphorylation Status and Hippo-Salvador Association

Par-1 regulates the Hippo signaling pathway in Drosophila melanogaster by modifying the phosphorylation status of Hippo and also by inhibiting the interaction of Hippo and Salvador.