RESUMO
Cellular organization through cytoskeletal trafficking is a process of fundamental importance. Highly specialized systems evolved that enable motors to identify and select the optimal tracks for motility. In this chapter, we examine the profound effect of actin filament networks on myosin motility patterns. We argue that the myosin classes have adaptations that allow them to detect local structural and chemical cues on actin. These cues are often arranged in a coherent manner on actin filament networks, allowing for directed transport over long distances. We identify a number of potentially important cues, ranging from the biochemical states of actin subunits all the way to multi-filament networks and bundles.
Assuntos
Actinas , Miosinas , Citoesqueleto de Actina , Actinas/metabolismo , Movimento , Miosinas/metabolismoRESUMO
Fallopian tube secretory epithelial cells (FTSECs) are likely the main precursor cell type of high-grade serous ovarian cancers (HGSOCs), but these tumors may also arise from ovarian surface epithelial cells (OSECs). We profiled global landscapes of gene expression and active chromatin to characterize molecular similarities between OSECs (n = 114), FTSECs (n = 74), and HGSOCs (n = 394). A one-class machine learning algorithm predicts that most HGSOCs derive from FTSECs, with particularly high FTSEC scores in mesenchymal-type HGSOCs (padj < 8 × 10-4). However, a subset of HGSOCs likely derive from OSECs, particularly HGSOCs of the proliferative type (padj < 2 × 10-4), suggesting a dualistic model for HGSOC origins. Super-enhancer (SE) landscapes were also more similar between FTSECs and HGSOCs than between OSECs and HGSOCs (p < 2.2 × 10-16). The SOX18 transcription factor (TF) coincided with a HGSOC-specific SE, and ectopic overexpression of SOX18 in FTSECs caused epithelial-to-mesenchymal transition, indicating that SOX18 plays a role in establishing the mesenchymal signature of fallopian-derived HGSOCs.
Assuntos
Neoplasias Ovarianas/genética , Fatores de Transcrição SOXF/genética , Adulto , Idoso , Linhagem Celular , Linhagem Celular Tumoral , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Transição Epitelial-Mesenquimal , Tubas Uterinas/metabolismo , Tubas Uterinas/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Aprendizado de Máquina , Pessoa de Meia-Idade , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Ovário/metabolismo , Ovário/patologia , RNA-Seq , Fatores de Transcrição SOXF/metabolismo , Análise de Célula Única , TranscriptomaRESUMO
We sought to identify susceptibility genes for high-grade serous ovarian cancer (HGSOC) by performing a transcriptome-wide association study of gene expression and splice junction usage in HGSOC-relevant tissue types (N = 2,169) and the largest genome-wide association study available for HGSOC (N = 13,037 cases and 40,941 controls). We identified 25 transcriptome-wide association study significant genes, 7 at the junction level only, including LRRC46 at 19q21.32, (P = 1 × 10-9), CHMP4C at 8q21 (P = 2 × 10-11) and a PRC1 junction at 15q26 (P = 7 × 10-9). In vitro assays for CHMP4C showed that the associated variant induces allele-specific exon inclusion (P = 0.0024). Functional screens in HGSOC cell lines found evidence of essentiality for three of the new genes we identified: HAUS6, KANSL1 and PRC1, with the latter comparable to MYC. Our study implicates at least one target gene for 6 out of 13 distinct genome-wide association study regions, identifying 23 new candidate susceptibility genes for HGSOC.
Assuntos
Carcinoma Epitelial do Ovário/genética , Neoplasias Ovarianas/genética , Processamento Alternativo , Proteínas de Ciclo Celular/genética , Linhagem Celular Tumoral , Bases de Dados Genéticas , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Técnicas de Inativação de Genes , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Modelos Genéticos , Proteínas Nucleares/genética , Polimorfismo de Nucleotídeo Único , TranscriptomaRESUMO
Coiled-coil fusions are a useful approach to enforce dimerization in protein engineering. However, the final structures of coiled-coil fusion proteins have received relatively little attention. Here, we determine the structural outcome of adjacent parallel and antiparallel coiled coils. The targets are coiled coils that stabilize myosin-10 in single-molecule biophysical studies. We reveal the solution structure of a short, antiparallel, myosin-10 coiled-coil fused to the parallel GCN4-p1 coiled coil. Surprisingly, this structure is a continuous, antiparallel coiled coil where GCN4-p1 pairs with myosin-10 rather than itself. We also show that longer myosin-10 segments in these parallel/antiparallel fusions are dynamic and do not fold cooperatively. Our data resolve conflicting results on myosin-10 selection of actin filament bundles, demonstrating the importance of understanding coiled-coil orientation and stability.
