ABSTRACT
All cancer-causing human papillomavirus (HPV) E6 oncoproteins have a C-terminal PDZ-binding motif (PBM), which correlates with oncogenic potential. Nonetheless, several HPVs with little or no oncogenic potential also have an E6 PBM, with minor sequence differences affecting PDZ protein selectivity. Furthermore, certain HPV types have a phospho-acceptor site embedded within the PBM. We therefore compared HPV-18, HPV-66 and HPV-40 E6 proteins to examine the possible link between the ability to target multiple PDZ proteins and the acquisition of a phospho-acceptor site. The mutation of essential residues in HPV-18E6 reduces its phosphorylation, and fewer PDZ substrates are bound. In contrast, the generation of consensus phospho-acceptor sites in HPV-66 and HPV-40 E6 PBMs increases the PDZ proteins recognized. Thus, although phosphorylation of the E6 PBM and PDZ protein recognition are mutually exclusive, they are closely linked, with the acquisition of a phospho-acceptor site also contributing to an expansion in the number of PDZ proteins bound.
Subject(s)
Alphapapillomavirus/metabolism , DNA-Binding Proteins/metabolism , Human papillomavirus 18/metabolism , Oncogene Proteins, Viral/metabolism , Adaptor Proteins, Signal Transducing/chemistry , Adaptor Proteins, Signal Transducing/metabolism , Alphapapillomavirus/pathogenicity , Amino Acid Motifs , Cell Adhesion Molecules/chemistry , Cell Adhesion Molecules/metabolism , Cyclic AMP-Dependent Protein Kinases/metabolism , DNA-Binding Proteins/chemistry , DNA-Binding Proteins/genetics , Discs Large Homolog 1 Protein/chemistry , Discs Large Homolog 1 Protein/metabolism , Guanylate Kinases/chemistry , Guanylate Kinases/metabolism , HEK293 Cells , Human papillomavirus 18/pathogenicity , Humans , Membrane Proteins/chemistry , Membrane Proteins/metabolism , Mutant Proteins/chemistry , Mutant Proteins/metabolism , Oncogene Proteins, Viral/chemistry , Oncogene Proteins, Viral/genetics , PDZ Domains , Phosphorylation , Protein Binding , Tumor Suppressor Proteins/chemistry , Tumor Suppressor Proteins/metabolismABSTRACT
BACKGROUND: Genetic risk variants in the hemizygous allele may influence neuropsychiatric manifestations and clinical course in 3q29 deletion carriers. METHODS: In-depth phenotypic assessment in two deletion carriers included medical records, medical, genetic, psychiatric and neuropsychological evaluations, brain MRI scan and EEG. Blood samples were analyzed for copy number variations, and deep sequencing of the affected 3q29 region was performed in patients and seven first-degree relatives. Risk variants were identified through bioinformatic analysis. RESULTS: One deletion carrier was diagnosed with learning difficulties and childhood autism, the other with mild intellectual disability and schizophrenia. EEG abnormalities in childhood normalized in adulthood in both. Cognitive abilities improved during adolescence in one deletion carrier. Both had microcytic, hypochromic erythrocytes and suffered from chronic pain and fatigue. Molecular and bioinformatic analyses identified risk variants in the hemizygous allele that were not present in the homozygous state in relatives in genes involved in cilia function and insulin action in the autistic individual and in synaptic function and neurosteroid transport in the subject with schizophrenia. CONCLUSION: 3q29 deletion carriers may undergo developmental phenotypic transition and need regular medical follow-up. Identified risk variants in the remaining hemizygous allele should be explored further in autism and schizophrenia research.
Subject(s)
Alleles , Autistic Disorder/genetics , Chromosomes, Human, Pair 3/genetics , Genetic Variation , Phenotype , Schizophrenia/genetics , Sequence Deletion/genetics , Adolescent , Adult , Child , Child, Preschool , Chromosome Structures , Cilia/genetics , DNA Copy Number Variations/genetics , Developmental Disabilities/genetics , Discs Large Homolog 1 Protein/chemistry , Discs Large Homolog 1 Protein/genetics , Female , Genetic Predisposition to Disease/genetics , Humans , Infant , Intellectual Disability/genetics , Male , Young AdultABSTRACT
The canonical Scribble polarity complex is implicated in regulation of epithelial junctions and apical polarity. Here, we show that SGEF, a RhoG-specific GEF, forms a ternary complex with Scribble and Dlg1, two members of the Scribble complex. SGEF targets to apical junctions in a Scribble-dependent fashion and functions in the regulation of actomyosin-based contractility and barrier function at tight junctions as well as E-cadherin-mediated formation of adherens junctions. Surprisingly, SGEF does not control the establishment of polarity. However, in 3D cysts, SGEF regulates the formation of a single open lumen. Interestingly, SGEF's nucleotide exchange activity regulates the formation and maintenance of adherens junctions, and in cysts the number of lumens formed, whereas SGEF's scaffolding activity is critical for regulation of actomyosin contractility and lumen opening. We propose that SGEF plays a key role in coordinating junctional assembly and actomyosin contractility by bringing together Scribble and Dlg1 and targeting RhoG activation to cell-cell junctions.