Src Kinase Determines the Dynamic Exchange of the Docking Protein NEDD9 (Neural Precursor Cell Expressed Developmentally Down-regulated Gene 9) at Focal Adhesions

Dynamic exchange of molecules between the cytoplasm and integrin-based focal adhesions provides a rapid response system for modulating cell adhesion. Increased residency time of molecules that regulate adhesion turnover contributes to adhesion stability, ultimately determining migration speed across two-dimensional surfaces. In the present study we test the role of Src kinase in regulating dynamic exchange of the focal adhesion protein NEDD9/HEF1/Cas-L. Using either chemical inhibition or fibroblasts genetically null for Src together with fluorescence recovery after photobleaching (FRAP), we find that Src significantly reduces NEDD9 exchange at focal adhesions. Analysis of NEDD9 mutant constructs with the two major Src-interacting domains disabled revealed the greatest effects were due to the NEDD9 SH2 binding domain. This correlated with a significant change in two-dimensional migratory speed. Given the emerging role of NEDD9 as a regulator of focal adhesion stability, the time of NEDD9 association at the focal adhesions is key in modulating rates of migration and invasion. Our study suggests that Src kinase activity determines NEDD9 exchange at focal adhesions and may similarly modulate other focal adhesion-targeted Src substrates to regulate cell migration.NHMRC Grant 63251

NEDD9 regulates 3D migratory activity independent of the Rac1 morphology switch in glioma and neuroblastoma.

Metastasizing tumor cells must transmigrate the dense extracellular matrix that surrounds most organs. The use of three-dimensional (3D) collagen gels has revealed that many cancer cells can switch between different modes of invasion that are characterized by distinct morphologies (e.g., rounded vs. elongated). The adhesion protein NEDD9 has the potential to regulate the switch between elongated and rounded morphologies; therefore, its role was interrogated in the invasion switch of glioblastoma and neuroblastoma tumors that similarly derive from populations of neural crest cells. Interestingly, siRNA-mediated depletion of NEDD9 failed to induce cell rounding in glioma or neuroblastoma cells, contrasting the effects that have been described in other tumor model systems. Given that Rac1 GTPase has been suggested to mediate the switch between elongated and rounded invasion, the functionality of the Rac1 morphology switch was evaluated in the glioma and neuroblastoma cells. Using both dominant-negative Rac1 and Rac1-specific siRNA, the presence of this morphologic switch was confirmed in the neuroblastoma, but not in the glioma cells. However, in the absence of a morphologic change following NEDD9 depletion, a significant decrease in the cellular migration rate was observed. Thus, the data reveal that NEDD9 can regulate 3D migration speed independent of the Rac1 morphology switch. IMPLICATIONS: NEDD9 targeting is therapeutically viable as it does not stimulate adaptive changes in glioma and neuroblastoma invasion.National Health and Medical Research Council (NHMRC) grant 63251

Isolation and characterization of novel microsatellite markers and their application for diversity assessment in cultivated groundnut (Arachis hypogaea)

<p>Abstract</p> <p>Background</p> <p>Cultivated peanut or groundnut (<it>Arachis hypogaea </it>L.) is the fourth most important oilseed crop in the world, grown mainly in tropical, subtropical and warm temperate climates. Due to its origin through a single and recent polyploidization event, followed by successive selection during breeding efforts, cultivated groundnut has a limited genetic background. In such species, microsatellite or simple sequence repeat (SSR) markers are very informative and useful for breeding applications. The low level of polymorphism in cultivated germplasm, however, warrants a need of larger number of polymorphic microsatellite markers for cultivated groundnut.</p> <p>Results</p> <p>A microsatellite-enriched library was constructed from the genotype TMV2. Sequencing of 720 putative SSR-positive clones from a total of 3,072 provided 490 SSRs. 71.2% of these SSRs were perfect type, 13.1% were imperfect and 15.7% were compound. Among these SSRs, the GT/CA repeat motifs were the most common (37.6%) followed by GA/CT repeat motifs (25.9%). The primer pairs could be designed for a total of 170 SSRs and were optimized initially on two genotypes. 104 (61.2%) primer pairs yielded scorable amplicon and 46 (44.2%) primers showed polymorphism among 32 cultivated groundnut genotypes. The polymorphic SSR markers detected 2 to 5 alleles with an average of 2.44 per locus. The polymorphic information content (PIC) value for these markers varied from 0.12 to 0.75 with an average of 0.46. Based on 112 alleles obtained by 46 markers, a phenogram was constructed to understand the relationships among the 32 genotypes. Majority of the genotypes representing subspecies <it>hypogaea </it>were grouped together in one cluster, while the genotypes belonging to subspecies <it>fastigiata </it>were grouped mainly under two clusters.</p> <p>Conclusion</p> <p>Newly developed set of 104 markers extends the repertoire of SSR markers for cultivated groundnut. These markers showed a good level of PIC value in cultivated germplasm and therefore would be very useful for germplasm analysis, linkage mapping, diversity studies and phylogenetic relationships in cultivated groundnut as well as related <it>Arachis </it>species.</p

Exploring the Oversight of Risk Management in UK Higher Education Institutions: The Case of Audit Committees

We explore how audit committees (ACs) oversee risk management in UK Higher Education Institutions (HEIs), using semi-structured interviews, attendance at AC meetings and documentary analysis. We find that the AC’s oversight seems constrained by a fixation on the process of risk management, an over-reliance on risk registers, and varying levels of emphasis on operational risks. Theoretically, the AC’s oversight reflects different shades of symbolic and substantive activities designed to maintain the HEI’s legitimacy and that of its governing board, hence providing a symbolic representation. We raise concerns as to the AC’s ability to monitor effectively the HEIs’ risk management practices

Tropomyosin Regulates Cell Migration during Skin Wound Healing

Precise orchestration of actin polymer into filaments with distinct characteristics of stability, bundling, and branching underpins cell migration. A key regulator of actin filament specialization is the tropomyosin family of actin-associating proteins. This multi-isoform family of proteins assemble into polymers that lie in the major groove of polymerized actin filaments, which in turn determine the association of molecules that control actin filament organization. This suggests that tropomyosins may be important regulators of actin function during physiological processes dependent on cell migration, such as wound healing. We have therefore analyzed the requirement for tropomyosin isoform expression in a mouse model of cutaneous wound healing. We find that mice in which the 9D exon from the TPM3/γTm tropomyosin gene is deleted (γ9D -/-) exhibit a more rapid wound-healing response 7 days after wounding compared with wild-type mice. Accelerated wound healing was not associated with increased cell proliferation, matrix remodeling, or epidermal abnormalities, but with increased cell migration. Rac GTPase activity and paxillin phosphorylation are elevated in cells from γ9D -/- mice, suggesting the activation of paxillin/Rac signaling. Collectively, our data reveal that tropomyosin isoform expression has an important role in temporal regulation of cell migration during wound healing.(NHMRC) grant 51225

Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei And the First Black Hole Determination for NGC 205

We improve the dynamical black hole (BH) mass estimates in three nearby low-mass early-type galaxies--NGC 205, NGC 5102, and NGC 5206. We use new \hst/STIS spectroscopy to fit the star formation histories of the nuclei in these galaxies, and use these measurements to create local color--mass-to-light ratio (\ml) relations. We then create new mass models from \hst~imaging and combined with adaptive optics kinematics, we use Jeans dynamical models to constrain their BH masses. The masses of the central BHs in NGC 5102 and NGC 5206 are both below one million solar masses and are consistent with our previous estimates, $9.12_{-1.53}^{+1.84}\times10^5$\Msun~and $6.31_{-2.74}^{+1.06}\times10^5$\Msun~(3$\sigma$ errors), respectively. However, for NGC 205, the improved models suggest the presence of a BH for the first time, with a best-fit mass of $6.8_{-6.7}^{+95.6}\times10^3$\Msun~(3$\sigma$ errors). This is the least massive central BH mass in a galaxy detected using any method. We discuss the possible systematic errors of this measurement in detail. Using this BH mass, the existing upper limits of both X-ray, and radio emissions in the nucleus of NGC 205 suggest an accretion rate $\lesssim$$10^{-5}$ of the Eddington rate. We also discuss the color--\mleff~relations in our nuclei and find that the slopes of these vary significantly between nuclei. Nuclei with significant young stellar populations have steeper color--\mleff~relations than some previously published galaxy color--\mleff~relations.Comment: 31 pages, 19 figures, 6 tables, Accepted to Ap