Oncogenic Signaling Alters Cell Shape and Mechanics to Facilitate Cell Division under Confinement.

To divide in a tissue, both normal and cancer cells become spherical and mechanically stiffen as they enter mitosis. We investigated the effect of oncogene activation on this process in normal epithelial cells. We found that short-term induction of oncogenic Ras activates downstream mitogen-activated protein kinase (MEK-ERK) signaling to alter cell mechanics and enhance mitotic rounding, so that Ras-expressing cells are softer in interphase but stiffen more upon entry into mitosis.

Targeting Mechanoresponsive Proteins in Pancreatic Cancer: 4-Hydroxyacetophenone Blocks Dissemination and Invasion by Activating MYH14.

Metastasis is complex, involving multiple genetic, epigenetic, biochemical, and physical changes in the cancer cell and its microenvironment. Cells with metastatic potential are often characterized by altered cellular contractility and deformability, lending them the flexibility to disseminate and navigate through different microenvironments. We demonstrate that mechanoresponsiveness is a hallmark of pancreatic cancer cells.

Real-time fluorescence and deformability cytometry.

The throughput of cell mechanical characterization has recently approached that of conventional flow cytometers. However, this very sensitive, label-free approach still lacks the specificity of molecular markers. Here we developed an approach that combines real-time 1D-imaging fluorescence and deformability cytometry in one instrument (RT-FDC), thus opening many new research avenues.

Real-Time Deformability Cytometry: Label-Free Functional Characterization of Cells.

Real-time deformability cytometry (RT-DC) is a microfluidic technique that allows to capture and evaluate morphology and rheology of up to 1000 cells/s in a constricted channel. The cells are deformed without mechanical contact by hydrodynamic forces and are quantified in real-time without the need of additional handling or staining procedures. Segmented pictures of the cells are stored and can be used for further analysis.

Direct Interaction between TalinB and Rap1 is necessary for adhesion of Dictyostelium cells.

Background: The small G-protein Rap1 is an important regulator of cellular adhesion in Dictyostelium, however so far the downstream signalling pathways for cell adhesion are not completely characterized. In mammalian cells talin is crucial for adhesion and Rap1 was shown to be a key regulator of talin signalling.

Results: In a proteomic screen we identified TalinB as a potential Rap1 effector in Dictyostelium.

Rap1-dependent pathways coordinate cytokinesis in Dictyostelium.

Cytokinesis is the final step of mitosis when a mother cell is separated into two daughter cells. Major cytoskeletal changes are essential for cytokinesis; it is, however, not well understood how the microtubules and actomyosin cytoskeleton are exactly regulated in time and space. In this paper, we show that during the early stages of cytokinesis, in rounded-up Dictyostelium discoideum cells, the small G-protein Rap1 is activated uniformly at the cell cortex.

GxcC connects Rap and Rac signaling during Dictyostelium development.

Background: Rap proteins belong to the Ras family of small G-proteins. Dictyostelium RapA is essential and implicated in processes throughout the life cycle. In early development and chemotaxis competent cells RapA induces pseudopod formation by activating PI3K and it regulates substrate attachment and myosin disassembly via the serine/threonine kinase Phg2.

Daydreamer, a Ras effector and GSK-3 substrate, is important for directional sensing and cell motility.

How independent signaling pathways are integrated to holistically control a biological process is not well understood. We have identified Daydreamer (DydA), a new member of the Mig10/RIAM/lamellipodin (MRL) family of adaptor proteins that localizes to the leading edge of the cell. DydA is a putative Ras effector that is required for cell polarization and directional movement during chemotaxis.

Multiple regulatory mechanisms for the Dictyostelium Roco protein GbpC.

GbpC is a multidomain Roco protein in Dictyostelium, involved in transduction of intracellular cGMP that is produced by chemotactic signals. We have shown previously that cGMP binding to GbpC induces an intramolecular signaling cascade by activating subsequently the GEF, Ras, and kinase domains. In this study, we report on the cellular localization of GbpC.

Mitochondrial genotype and breast cancer predisposition.

Breast cancer is the most commonly diagnosed cancer in women. Despite recent advances in breast cancer research, a comprehensive set of genetic markers of increased breast cancer risk remain elusive. Recently mitochondrial DNA (mtDNA) mutations have been found in many types of cancer, including breast cancer.

Common mitochondrial polymorphisms as risk factor for endometrial cancer.

Endometrial carcinoma is the most commonly diagnosed gynaecological cancer in developed countries. Although the molecular genetics of this disease has been in the focus of many research laboratories for the last 20 years, relevant prognostic and diagnostic markers are still missing. At the same time mitochondrial DNA mutations have been reported in many types of cancer during the last two decades.

Breast cancer as a mitochondrial disorder (Review).

Mitochondria have been implicated in cell transformation since Otto Warburg considered 'respiration damage' to be a pivotal feature of cancer cells. Numerous somatic mitochondrial DNA (mtDNA) mutations have been found in various types of neoplasms, including breast cancer. Establishing the mtDNA mutation pattern in breast cancer cells may enhance the specificity of cancer diagnostics, detection and prediction of cancer growth rate and/or patients' outcomes; and therefore be used as a new molecular cancer bio-marker.

[The impact of mtDNA mutations on proteins structure in selected types of cancer].

Recently published papers report a large number of mitochondrial DNA mutations in many different cancer types, but their significance for electron transport chain proteins remains unknown. This review covers structural mutations of mitochondrial genes, choosing prostate cancer, esophageal cancer and epithelioma as research models. As all mitochondrial genes encode subunits of the electron transport chain, the review focuses on the consequences of structural mutations on cell metabolism.

Intramolecular activation mechanism of the Dictyostelium LRRK2 homolog Roco protein GbpC.

GbpC is a large multidomain protein involved in cGMP-mediated chemotaxis in the cellular slime mold Dictyostelium discoideum. GbpC belongs to the Roco family of proteins that often share a central core region, consisting of leucine-rich repeats, a Ras domain (Roc), a Cor domain, and a MAPKKKinase domain. In addition to this core, GbpC contains a RasGEF domain and two cGMP-binding domains.