Innovation performance in the space sector

The space sector is a high tech industry. It is generally considered as a major driver of growth and provides solutions to a number of socioeconomic challenges. This paper focuses on the role of national innovation systems on a country's capacity to innovate in the space sector. The paper analyzes the national innovation system through two dimensions: a) the innovation infrastructure; and b) the cluster environment. Longitudinal data is gathered to cover eleven countries in the space sector for nine time periods. To our knowledge, this paper is among the very first which provides evidence to showcase the dynamic relationship of national innovation systems and innovation capacity in the space sector, as it involves a panel data structure based on two dimensions simultaneously: a cross-sectional dimension and a timeseries dimension. Based on studying the number of space-related publications in Web of Science, our research results show that the number of individual researchers has a significant positive effect on a country's innovative performance. In contrast, no significant relationship between highly skilled workforce and innovative performance is found. These results indicate that research funds and policies of national governments directly targeting upstream scientific activities are more beneficial to improve innovative performances than a focus on downstream activities

Sorbin and SH3 domain-containing protein 2 (SORBS2) is a component of the acto-myosin ring at the apical junctional complex in epithelial cells

<div><p>SORBS2 is a scaffolding protein associated with Abl/Arg non-receptor tyrosine kinase pathways and is known to interact with actin and several other cytoskeletal proteins in various cell types. Previous BioID proximity labeling of tight and adherens junction proteins suggested that SORBS2 is a component of the apical junction complex of epithelial cells. We asked whether SORBS2 plays a previously unappreciated role in controlling perijunctional actin and tight junction barrier function. Using super resolution imaging we confirmed that SORBS2 is localized at the apical junction complex but farther from the membrane than ZO-1 and located partially overlapping both the tight- and adherens junctions with a periodic concentration that alternates with myosin IIB in polarized epithelial cells. Overexpression of GFP-SORBS2 recruited alpha-actinin, vinculin and N-WASP, and possibly CIP4 to cellular junctions. However, CRISPR-Cas9 knock-out of SORBS2 did not alter the localization- or immunofluorescent staining intensity of these or several other junctional- and cytoskeletal proteins. SORBS2 knock-out also did not affect the barrier function as measured by TER and dextran flux; nor did it change actin-dependent junction re-assembly as measured by Ca²⁺-switch and Latrunculin-B wash-out assays. The kinetics of HGF-induced cell scattering and wound healing, and dextran flux increase induced by PDGF also were unaffected by SORBS2 knock-out. SORBS2 concentrates with apical junctional actin that accumulates in response to knock-down of ZO-1 and ZO-2. In spite of our finding that SORBS2 is clearly a component of the apical junction complex, it does not appear to be required for either normal tight- or adherens junction assembly, structure or function or for growth factor-mediated changes in tight junction dynamics.</p></div

SORBS2 partially colocalizes with ZO-1 in murine bile canaliculi and with ZO-1 and E-cadherin in polarized MDCKII cells.

<p>(A) Confocal immunofluorescence analysis reveals that SORBS2 is localized to bile canalicular TJs in murine liver and is partially colocalized with ZO-1 in X, Y and Z planes (63x oil objective was used, scale bar: 10 μm). Images are maximum intensity projections of Z-stacks (total depth 4.5 μm). Merged images show that they overlap, but that ZO-1 also extends more apically. (B) SORBS2 is colocalized with ZO-1 and the apical portion of E-cadherin in polarized MDCKII cells cultured on Transwell filters for nine days (63x oil objective used, scale bar: 10 μm). Images are maximum intensity projections of Z-stacks (total depth for X-Y images ca 4.5 μm (to avoid the strong signal from basal actin stress fibers). SORBS2 is also faintly visible as green dots at the bottom of the cells (cross sections of actin stress fibers) in Z projections, especially in panel B. (full stack:10 μm).</p

STED super resolution microscopy reveals that SORBS2 colocalizes with apical junctional actin and afadin, and partially overlaps with ZO-1, occludin and E-cadherin in polarized MDCKII cells.

<p>(A) Super resolution microscopy shows that SORBS2 in fact only partially colocalizes with ZO-1 in a discontinuous pattern along cell-cell contacts. Line scans of fluorescence intensity at 90 degrees to the cell contacts confirmed the visual observations, graph to right (N = 20, mean ± SEM). (B) As with ZO-1, SORBS2 is decorating occludin in a discontinuous pattern at cell-cell junctions and we noticed that SORBS2, at this level, is absent from tricellular junctions. (C) SORBS2 is colocalized with junctional actin, as confirmed both by visual appearance and line scan results. (D) Myosin IIB is localized in a discontinuous pattern at approximately the same distance from the cell-cell junction as SORBS2, but to note is that myosin IIB is present where SORBS2 is absent. (E) The very apical portion of E-cadherin is in the same X/Y plane as SORBS2, but SORBS2 localized farther from the membrane than E-cadherin. Scale bar: 0.5 μm. Images are maximum intensity projections of Z-stacks, total depth 2 μm.</p

Tight junction, adherens junction and cytoskeletal proteins are not changed either at cell-cell contacts or at actin stress fibers in SORBS2 knock-out cells.

<p>(A) Localization of the TJ proteins ZO-1 and cingulin is not changed in SORBS2 KO cells (right panel) as compared to WT cells (left panel). SORBS2 is present in a discontinuous pattern at apical cell-cell contacts in WT cells (left panel) and is not visible in SORBS2 KO cells (right panel). The adherens junction proteins E-cadherin (panel A) and afadin (panel B) are both unchanged by SORBS2 KO as compared to WT cells (right and left panels respectively). (B) the cytoskeletal proteins actin, vinculin and myosin IIB are also not affected by SORBS2 KO (right panel) as compared to WT cells (left panel). (C) SORBS2 is also localized at actin stress fibers (WT, left panel) and is not visible in SORBS2 KO cells (right panel). Actin, vinculin and myosin IIB are not changed at actin stress fibers in SORBS2 KO cells (right panel) as compared to WT cells (left panel). 63x objective was used, apical images are maximum intensity projections (depth range: 1.7–3 μm depending on the basolateral distribution of each protein, scale bar: 20 μm). Basal images: SORBS2 and actin are maximum intensity projections (1.26 μm), vinculin (0.82 μm) and Myosin IIB (0.42 μm). Scale bar: 20 μm.</p

Knock-out of SORBS2 does not affect TJ recovery after calcium switch.

<p>(A) SORBS2 colocalizes with ZO-1 in WT SKco15 cells under normal culture conditions. (B) After overnight culture in low-calcium both WT and SORBS2 KO cells are rounded up and no normal cell-cell junctions are visible. Already one hour after normal calcium is restored cell-cell junctions are starting to recover (C) and the recovery progresses after 2 hours (D) and after 7 hours (E) the cell-cell contacts look normal by immunofluorescent microscopy. Scale bar: 20 μm. Images are maximum intensity projections of Z-stacks (total depth:10 μm). (F) TER is high in both WT and SORBS2 KO SKco15cells before calcium removal. However, after overnight low calcium TER is almost undetectable. TER recovers as the cell-cell contacts are reassembled and is almost fully recovered 24 hours after normal calcium is restored. Data shown are mean ±SEM of duplicate samples.</p

SORBS2 colocalizes with the thick contractile perijunctional actin, alpha-actinin and myosin structure induced by ZO-1, ZO-2 double knock-down in MDCKII cells.

<p>Super resolution Airyscan immunofluorescent images confirms that actin is redistributed in ZO-1, ZO-2 dKD cells (C, lower panel, middle image) and SORBS2 which is normally colocalized with apical junctional actin in MDCKII cells (C, upper panel) is now redistributed with actin (C, lower panel, left and right images). Myosin IIB and alpha-actinin are also redistributed in ZO-1, ZO-2 dKD cells (Myosin IIB: A, lower panel center and D, lower panel center; alpha-actinin: B, lower panel center and D, lower panel left) as compared to cells rescued with ZO-1 (Myosin IIB: A and D, top panel center; alpha-actinin: B and D, top panel center). SORBS2 appears to co-localize with alpha-actinin and mostly colocalize with actin in both ZO-1 rescue cells and ZO-1, ZO-2 dKD cells (alpha-actinin: B, right images in upper and lower panel; actin: C, right images in upper and lower panel). Myosin IIB in ZO-1, ZO-2 dKD cells decorate the distal part of both SORBS2 (A: right image in lower panel) and alpha-actinin (D: right image in lower panel). (63x oil objective used, scale bar: 20 μm). Images are maximum intensity projection of Z-stacks (total depth range: 2–3.3 μm).</p

HGF-induced cell scattering and accelerated wound healing is the same in SORBS2 knock-out and control MDCKII cells.

<p>(A) SORBS2 colocalizes with ZO-1 in WT MDCKII cells. (B) Twenty-four hours after HGF treatment cells scatter and ZO-1 becomes discontinuous at cell-cell contacts in both WT and SORBS2 KO cells, as does SORBS2 in WT cells. (C) Forty-eight hours after HGF treatment cell scattering patterns again looks the same in both WT and SORBS2 KO cells. (D) HGF speeds up wound healing in both SORBS2 KO and WT cells (12 hours) as compared to normal complete media (28 hours), but there is no difference between SORBS2 KO and WT MDCKII cells (63 x oil objective, scale bar: 20 μm).</p