title: A novel functional screen in human cells identifies MOCA as a negative regulator of Wnt signaling.
abstract: Aberrant Wnt signal transduction is involved in many human diseases such as cancer and neurodegenerative disorders. The key effector protein of the canonical Wnt pathway is beta-catenin, which functions with T-cell factor/lymphoid enhancer factor (TCF/LEF) to activate gene transcription that leads to expression of Wnt target genes. In this study we provide results obtained from a novel functional screen of a human brain cDNA library used to identify 63 genes that are putative negative Wnt regulators. These genes were divided into eight functional groups that include known canonical and noncanonical Wnt pathway components and genes that had not yet been assigned to the Wnt pathway. One of the groups, the presenilin-binding proteins, contains the modifier of cell adhesion (MOCA) gene. We show that MOCA is a novel inhibitor of Wnt/beta-catenin signaling. MOCA forms a complex with beta-catenin and inhibits transcription of known Wnt target genes. Epistasis experiments indicate that MOCA acts to reduce the levels of nuclear beta-catenin, increase the levels of membrane-bound beta-catenin, and enhances cell-cell adhesion. Therefore, our data indicate that MOCA is a novel Wnt negative regulator and demonstrate that this screening approach can be a rapid means for isolation of new Wnt regulators.
authors: Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
authors: Elanite
authors: E
authors: Caspi
authors: Rina
authors: R
authors: Rosin-Arbesfeld
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D015536:Down-Regulation; D015723:Gene Library; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D021381:Protein Transport; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D013816:Thermodynamics; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism
chemical_list: C485840:DOCK3 protein, human; D020662:Guanine Nucleotide Exchange Factors; D009419:Nerve Tissue Proteins; D012097:Repressor Proteins; D051153:Wnt Proteins; D051176:beta Catenin