Cell Boundary Formation Research Articles

Electroacupuncture in promoting neural repair after spinal cord injury: Inhibiting the Notch signaling pathway and regulating downstream proteins expression.

Spinal cord injury (SCI) is one of the serious central nervous system injuries and the incidence of SCI continues to increase. Previous studies have indicated that electroacupuncture (EA) is beneficial for promoting recovery after SCI. In the present study, we attempted to evaluate how EA can promote the neural repair in SCI model rats by observing changes in the Notch signaling pathway. Experimental rats were randomly divided into four groups. Each group had its own intervention period: 1 day, 7 days, 14 days, and 28 days, and five randomized subgroups: blank control (B) group, blank electroacupuncture (BE) group, sham operation (S) group, model control (M) group and EA group. Animals in the EA group and the BE group were treated with EA at Dazhui (GV14) and Mingmen (GV4) acupoints for 20 min. After the intervention period, the Basso-Beattie-Bresnahan (BBB) score was used to evaluate the neurological function. We found that BBB score increased in EA-treated groups. Hematoxylin and eosin staining was used to observe pathological changes in the injured spinal cord and the results showed that EA therapy could promote the repair of injured spinal cord tissue. Immunohistochemistry and Western blot methods were used to detect the expression of proteins Delta1, Presenilin1, Hes1, and Hes5 in the injured spinal cord. The results showed that the expression levels of Delta1, Presenilin1, Hes1, and Hes5 increased significantly after SCI and decreased after EA treatment. Our study suggested that the possible mechanism by which EA could benefit the recovery after SCI in rats may include inhibiting the Notch signaling pathway and regulating the downstream proteins expression. In addition, our study can provide reference for selecting acupoints and treatment cycle in the treatment of SCI.

FGF signaling is required for brain left–right asymmetry and brain midline formation

Early disruption of FGF signaling alters left–right (LR) asymmetry throughout the embryo. Here we uncover a role for FGF signaling that specifically disrupts brain asymmetry, independent of normal lateral plate mesoderm (LPM) asymmetry. When FGF signaling is inhibited during mid-somitogenesis, asymmetrically expressed LPM markers southpaw and lefty2 are not affected. However, asymmetrically expressed brain markers lefty1 and cyclops become bilateral. We show that FGF signaling controls expression of six3b and six7, two transcription factors required for repression of asymmetric lefty1 in the brain. We found that Z0-1, atypical PKC (aPKC) and β-catenin protein distribution revealed a midline structure in the forebrain that is dependent on a balance of FGF signaling. Ectopic activation of FGF signaling leads to overexpression of six3b, loss of organized midline adherins junctions and bilateral loss of lefty1 expression. Reducing FGF signaling leads to a reduction in six3b and six7 expression, an increase in cell boundary formation in the brain midline, and bilateral expression of lefty1. Together, these results suggest a novel role for FGF signaling in the brain to control LR asymmetry, six transcription factor expressions, and a midline barrier structure.

High Performance Hybrid Functional Petri Net Simulations of Biological Pathway Models on CUDA

Hybrid functional Petri nets are a wide-spread tool for representing and simulating biological models. Due to their potential of providing virtual drug testing environments, biological simulations have a growing impact on pharmaceutical research. Continuous research advancements in biology and medicine lead to exponentially increasing simulation times, thus raising the demand for performance accelerations by efficient and inexpensive parallel computation solutions. Recent developments in the field of general-purpose computation on graphics processing units (GPGPU) enabled the scientific community to port a variety of compute intensive algorithms onto the graphics processing unit (GPU). This work presents the first scheme for mapping biological hybrid functional Petri net models, which can handle both discrete and continuous entities, onto compute unified device architecture (CUDA) enabled GPUs. GPU accelerated simulations are observed to run up to 18 times faster than sequential implementations. Simulating the cell boundary formation by Delta-Notch signaling on a CUDA enabled GPU results in a speedup of approximately 7x for a model containing 1,600 cells.

Eph-B2/Ephrin-B2 Interaction Plays a Major Role In the Adhesion and Survival of WM Cells In the Context of the Bone Marrow Microenvironment

AbstractAbstract 142 Introduction:Receptor tyrosine kinases (RTKs) are key regulators of the development and progression of many types of cancer. The Eph receptors represent the largest family of RTKs, which are used extensively throughout embryogenesis and development but detected in adult normal tissues. Elevated levels of expression of Eph receptors was found in a wide range of cancers and correlated with aggressive disease and metastasis. This is, triggered by a wide array of cellular responses, including cell boundary formation, motility, adhesion, and repulsion. Waldenstrom macroglobulinemia (WM) is characterized by widespread involvement of the bone marrow, indicating homing and adhesion of the malignant cells to specific niches in the bone marrow, which provides a protective environment for the survival and proliferation of these cells. Direct adhesion to endothelial cells and several growth factors and cytokines secreted by endothelial cells in the BM were shown to regulate tumor proliferation. In this study we aimed to characterize the role of RTKs, specifically Eph-B2 receptor, in the interaction of WM cells with the BM microenvironment including cell adhesion, proliferation, and cell-cycle. Methods and Results:We first examined the expression and activation (phosphorylation) of different RTKs in primary WM samples and cell lines using an antibody-based RTK-array. Eph-B2 receptor was activated in all patient samples compared to control, with a 5-fold increase in CD19+ WM cells, and we further confirmed that Eph-B2 was phosphorylated in WM cell lines, BCWM.1, and in IgM secreting cell lines RL, MEC-1. We next examined the activity of Ephrin-B2/Eph-B2 on adhesion and migration of WM cells. Treating starved WM cells with recombinant ephrin-B2 (the ligand of Eph-B2) activated cell-adhesion signaling, including focal adhesion kinase (FAK), Src, p130, paxilin and cofilin, but had no effect on WM cell chemotaxis. Moreover, we found that ephrin-B2 was highly expressed on endothelial cells isolated from the BM of WM patients and on HUVEC cells. Inhibition of ephrin-B2 on the endothelial cells or Eph-B2 on the WM cells with blocking antibodies inhibited the adhesion of the WM cells to endothelial cells, as well as the cytoskeletal signaling in WM cells induced by co-culture with endothelial cells. Consequently, inhibition of the ephrin-B2/Eph-B2 interaction reversed the proliferative and cell cycle effect in WM cell which was induced by co-culture with endothelial cells. This was confirmed using BrdU proliferation assay, flow cytometry for cell cycle, and by immuno-blotting to confirm the effect on proliferative signaling pathways including PI3K kinase and cell cycle related proteins including Cyclin-D, Cyclin-E and p-Rb. Conclusion:This study examines the interaction of Eph-B2 receptor in WM and shows that ephrin- B2/Eph-B2 axis regulates adhesion, activation of downstream signaling of integrin-related molecules, survival and cell cycle progression through the interaction of tumor cells with endothelial cells. This provides the basis for further studies to explore Eph-B2 as a novel therapeutic target in WM. Disclosures:Ghobrial:Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees.

Cloning and expression of the large zebrafish protocadherin gene, Fat

The cadherin superfamily members play an important role in mediating cell–cell contact and adhesion (Takeichi, M., 1991. Cadherin cell adhesion receptors as a morphogenetic regulator. Science 251, 1451–1455). A distinct subfamily, neither belonging to the classical or protocadherins includes Fat, the largest member of the cadherin super-family. Fat was originally identified in Drosophila. Subsequently, orthologues of Fat have been described in man (Dunne, J., Hanby, A. M., Poulsom, R., Jones, T. A., Sheer, D., Chin, W. G., Da, S. M., Zhao, Q., Beverley, P. C., Owen, M. J., 1995. Molecular cloning and tissue expression of FAT, the human homologue of the Drosophila fat gene that is located on chromosome 4q34–q35 and encodes a putative adhesion molecule. Genomics 30, 207–223), rat (Ponassi, M., Jacques, T. S., Ciani, L., ffrench, C. C., 1999. Expression of the rat homologue of the Drosophila fat tumour suppressor gene. Mech. Dev. 80, 207–212) and mouse (Cox, B., Hadjantonakis, A. K., Collins, J. E., Magee, A. I., 2000. Cloning and expression throughout mouse development of mfat1, a homologue of the Drosophila tumour suppressor gene fat [In Process Citation]. Dev. Dyn. 217, 233–240). In Drosophila, Fat has been shown to play an important role in both planar cell polarity and cell boundary formation during development. In this study we describe the characterization of zebrafish Fat, the first non-mammalian, vertebrate Fat homologue to be identified. The Fat protein has 64% amino acid identity and 80% similarity to human FAT and an identical domain structure to other vertebrate Fat proteins. During embryogenesis fat mRNA is expressed in the developing brain, specialised epithelial surfaces the notochord, ears, eyes and digestive tract, a pattern similar but distinct to that found in mammals.