Systematic mapping of protein-protein interactions, or 'interactome' mapping, was initiated in model organisms, starting with defined biological processes and then expanding to the scale of the proteome. Although far from complete, such maps have revealed global topological and dynamic features of interactome networks that relate to known biological properties, suggesting that a human interactome map will provide insight into development and disease mechanisms at a systems level. Here we describe an initial version of a proteome-scale map of human binary protein-protein interactions. Using a stringent, high-throughput yeast two-hybrid system, we tested pairwise interactions among the products of approximately 8,100 currently available Gateway-cloned open reading frames and detected approximately 2,800 interactions. This data set, called CCSB-HI1, has a verification rate of approximately 78% as revealed by an independent co-affinity purification assay, and correlates significantly with other biological attributes. The CCSB-HI1 data set increases by approximately 70% the set of available binary interactions within the tested space and reveals more than 300 new connections to over 100 disease-associated proteins. This work represents an important step towards a systematic and comprehensive human interactome project.

The mechanisms regulating the generation of cell diversity in the mammalian cerebral cortex are beginning to be elucidated. In that regard, Hairy/Enhancer of split (Hes) 1 and 5 are basic helix-loop-helix (bHLH) factors that inhibit the differentiation of pluripotent cortical progenitors into neurons. In contrast, a related Hes family member termed Hes6 promotes neurogenesis. It is shown here that knockdown of endogenous Hes6 causes supernumerary cortical progenitors to differentiate into cells that exhibit an astrocytic morphology and express the astrocyte marker protein GFAP. Conversely, exogenous Hes6 expression in cortical progenitors inhibits astrocyte differentiation. The negative effect of Hes6 on astrocyte differentiation is independent of its ability to promote neuronal differentiation. We also show that neither its proneuronal nor its anti-gliogenic functions appear to depend on Hes6 ability to bind to DNA via the basic arm of its bHLH domain. Both of these activities require Hes6 to be localized to nuclei, but only its anti-gliogenic function depends on two short peptides, LNHLL and WRPW, that are conserved in all Hes6 proteins. These findings suggest that Hes6 is an important regulator of the neurogenic phase of cortical development by promoting the neuronal fate while suppressing astrocyte differentiation. They suggest further that separate molecular mechanisms underlie the proneuronal and anti-gliogenic activities of Hes6 in cortical progenitor cells.

AIMIn recent years, the Wnt signalling pathway has been implicated in epithelial ovarian cancer and its members have potential as diagnostic, prognostic and therapeutic targets. Here we investigated the role of two Wnt receptor tyrosine kinases (RTKs), ROR1 and ROR2, and their putative ligand, Wnt5a, in ovarian cancer.METHODSImmunohistochemistry for ROR2 was performed in a large patient cohort, including benign controls, borderline tumours and epithelial ovarian cancer. In addition, siRNA was used to silence ROR1, ROR2 and Wnt5a individually, and together, in two ovarian cancer cell lines, and the effects on cell proliferation, adhesion, migration and invasion were measured.RESULTSROR2 expression is significantly increased in ovarian cancer patients compared to patients with benign disease. In vitro assays showed that silencing either receptor inhibits ovarian cancer cell migration and invasion, and concurrently silencing both receptors has an even stronger inhibitory effect on proliferation, migration and invasion.CONCLUSIONSROR2 expression is increased in epithelial ovarian cancer, and silencing ROR2 and its sister receptor ROR1 has a strong inhibitory effect on the ability of ovarian cancer cells to proliferate, migrate and invade through an extracellular matrix.

This is the first study to report the expression of ROR2 in breast cancer. Breast cancer patients expressing ROR2 had a significantly worse prognosis than those lacking ROR2. ROR2 may regulate both β-catenin-dependent and β-catenin-independent Wnt signalling pathways, and represents a potential diagnostic and therapeutic target.

Ovarian cancer survival remains poor despite recent advances in our understanding of genetic profiles. Unfortunately, the majority of ovarian cancer patients have recurrent disease after chemotherapy and lack other treatment options. Wnt signalling has been extensively implicated in cancer progression and chemoresistance. Therefore, we investigated the previously described Wnt receptors ROR1 and ROR2 as regulators of epithelial-to-mesenchymal transition (EMT) in a clinically relevant cell line model. The parental A2780- and cisplatin-resistant A2780-cis cell lines were used as a model of ovarian cancer chemoresistance. Proliferation, adhesion, migration and invasion were measured after transient overexpression of ROR1 and ROR2 in the parental A2780 cell line, and silencing of ROR1 and ROR2 in the A2780-cis cell line. Here we show that ROR1 and ROR2 expression is increased in A2780-cis cells, alongside β-catenin-independent Wnt targets. Knockdown of ROR1 and ROR2 significantly inhibited cell migration and invasion and simultaneous knockdown of ROR1 and ROR2 significantly sensitised cells to cisplatin, whilereas ROR overexpression in the parental cell line increased cell invasion. Therefore, ROR1 and ROR2 have the potential as novel drug targets in metastatic and recurrent ovarian cancer patients.

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Hairy/Enhancer of split (Hes) 6 is a basic helix-loop-helix protein that interacts with the transcriptional co-repressor, Groucho, and antagonizes the neural functions of the Notch pathway. More specifically, mouse Hes6 regulates cerebral corticogenesis by promoting neurogenesis and suppressing astrocyte differentiation. The molecular mechanisms underlying the anti-astrogenic function of Hes6 are poorly defined. Here we describe studies aimed at testing whether Hes6 inhibits astrocyte differentiation by antagonizing the transcription repression activity of Notch-activated Hes family members like Hes1. It is reported that Hes6 preferentially forms homodimers. Heterodimerization with Hes1 is antagonized in part by a conserved N-terminal patch of negatively charged residues. Mutation of this motif enhances heterodimerization with Hes1 and increases Hes6 ability to antagonize Hes1-mediated transcriptional repression. However, this mutation does not increase, but instead decreases, the antiastrogenic activity of Hes6. It is shown further that Hes6 harbors a second conserved sequence, a C-terminal SPXXSP motif. This sequence is phosphorylated by the mitogen activated protein kinase pathway and its mutation disrupts the anti-astrogenic activity of Hes6 without affecting its ability to suppress Hes1. Together, these observations suggest that Hes6 homodimers regulate astrocyte differentiation through mechanisms that depend on the phosphorylation of Hes6 C-terminal domain but are independent of its ability to suppress Hes1-mediated transcriptional repression. Keywords: astrocyte differentiation, cerebral cortex, Groucho, Hes, neurogenesis, Notch. In contrast to Hes1/Hes5, a related family member, Hes6, is not activated in response to Notch signaling and promotes, rather than inhibiting, neuronal differentiation in murine retinal explants (Bae et al. 2000), Xenopus neural plate (Koyano-Nakagawa et al. 2000), and cortical neural progenitor cells (Gratton et al. 2003;Jhas et al. 2006 These authors contributed equally to this study.Abbreviations used: bHLH, basic helix-loop-helix; CK2, protein kinase CK2; EMSA, electrophoretic mobility shift assay; ESE, Enhancer of split E; GFAP, glial fibrillary acidic protein; GFP, green fluorescent protein; Gro, Groucho; HA, hemagglutinin; HEK, human embryonic kidney; Hes, Hairy/Enhancer of split; MAPK, mitogen activated protein kinase; Ngn, neurogenin; TLE, transducin-like Enhancer of split.

BackgroundColorectal cancer (CRC) is closely linked to Wnt signalling, with 94 % of cases exhibiting a Wnt related mutation. ROR2 is a receptor tyrosine kinase that is thought to repress β-catenin dependent Wnt signalling. Our study aims to determine if ROR2 is epigenetically silenced in CRC and determine if in vitro silencing of ROR2 potentiates Wnt signalling, and alters the proliferative, migratory or invasive potential of cells.MethodsROR2 expression was examined in CRC cell lines and patient adenomas using qRT-PCR, while COBRA and bisulphite sequencing was used to analyse ROR2 promoter methylation. 258 patient primary tumour samples from publicly available databases were also examined for ROR2 expression and methylation. In addition, the functional effects of ROR2 modulation were investigated in HCT116 cells following ROR2 siRNA knockdown and in RKO and SW620 cells following ectopic ROR2 expression.ResultsReduced ROR2 expression was found to correlate with ROR2 promoter hypermethylation in colorectal cancer cell lines, carcinomas and adenomas. ROR2 expression was downregulated in 76.7 % (23/30) of CRC cell lines with increasing ROR2 promoter hypermethylation correlating with progressively lower expression. Analysis of 239 primary tumour samples from a publicly available cohort also found a significant correlation between reduced ROR2 expression and increased promoter methylation. Methylation analysis of 88 adenomas and 47 normal mucosa samples found greater percentage of adenoma samples to be methylated. Additional analysis also revealed that adenoma samples with reduced ROR2 expression also possessed ROR2 promoter hypermethylation. ROR2 knockdown in the CRC cell line HCT116 significantly decreased expression of the β-catenin independent Wnt targets genes JNK and NFATC1, increased cellular proliferation and migration but decreased invasion. When ROR2 was ectopically expressed in RKO and SW620 cells, there was no significant change to either cellular proliferation or migration.ConclusionROR2 is frequently epigenetically inactivated by promoter hypermethylation in the early stages of colorectal neoplasia and this may contribute to colorectal cancer progression by increasing cellular proliferation and migration.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2576-7) contains supplementary material, which is available to authorized users.