| 1. |
- Barkefors, Irmeli, et al.
(författare)
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Exocyst Complex Component 3-like 2 (EXOC3L2) Associates with the Exocyst Complex and Mediates Directional Migration of Endothelial Cells
- 2011
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 286:27, s. 24189-24199
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Tidskriftsartikel (refereegranskat)abstract
- The exocyst is a protein complex that ensures spatial targeting of exocytotic vesicles to the plasma membrane. We present microarray data obtained from differentiating mouse embryonic stem cell cultures that identify an up-regulation of exocyst complex component 3-like 2 (exoc3l2) mRNA in sprouting blood vessels. Vascular expression of exoc3l2 is confirmed by qPCR analysis of different mouse tissues and immunofluorescence analyses of mouse brain sections. We detect an up-regulation of exoc3l2 mRNA synthesis in primary human endothelial cells in response to VEGFA, and this response is enhanced when the cells are grown on a three-dimensional collagen I matrix. Myc-tagged EXOC3L2 co-precipitates with the exocyst protein EXOC4, and immunofluorescence detection of EXOC3L2 shows partial subcellular colocalization with EXOC4 and EXOC7. Finally, we show that exoc3l2 silencing inhibits VEGF receptor 2 phosphorylation and VEGFA-directed migration of cultured endothelial cells.
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| 2. |
- Blom, Magdalena, et al.
(författare)
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The atypical Rho GTPase RhoD is a regulator of actin cytoskeleton dynamics and directed cell migration
- 2017
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 352:2, s. 255-264
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Tidskriftsartikel (refereegranskat)abstract
- RhoD belongs to the Rho GTPases, a protein family responsible for the regulation and organization of the actin cytoskeleton, and, consequently, many cellular processes like cell migration, cell division and vesicle trafficking. Here, we demonstrate that the actin cytoskeleton is dynamically regulated by increased or decreased protein levels of RhoD. Ectopic expression of RhoD has previously been shown to give an intertwined weave of actin filaments. We show that this RhoD-dependent effect is detected in several cell types and results in a less dynamic actin filament system. In contrast, RhoD depletion leads to increased actin filament-containing structures, such as cortical actin, stress fibers and edge ruffles. Moreover, vital cellular functions such as cell migration and proliferation are defective when RhoD is silenced. Taken together, we present data suggesting that RhoD is an important component in the control of actin dynamics and directed cell migration.
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| 3. |
- Degerstedt, Oliver, et al.
(författare)
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Quantitative imaging of doxorubicin diffusion and cellular uptake in biomimetic gels with human liver tumor cells
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Novel tumor-on-a-chip approaches are increasingly used to investigate tumor progression and potential treatment options. To improve the effect of any cancer treatment it is important to have an in-depth understanding of drug diffusion, penetration across the tumor extracellular matrix and cellular uptake. In this study, we have developed a miniaturized chip where drug diffusion and cellular uptake in different hydrogel environments can be quantified at high resolution using live imaging. Diffusion of doxorubicin was reduced in a biomimetic hydrogel mimicking tissue properties of cirrhotic liver and early stage hepatocellular carcinoma (362 ± 109 µm2/s) as compared to an agarose gel (571 ± 145 µm2/s, p = 0.0085). The diffusion was further lowered to 164 ± 33 µm2/s (p = 0.0023) by preparing the biomimetic gel in cell media instead of phosphate buffered saline. The addition of liver tumor cells (Huh7 or HepG2) to the gel, at two different densities, did not significantly influence drug diffusion. Clinically relevant and quantifiable doxorubicin concentration gradients (1-20 µM) were established in the chip within one hour. Intracellular increases in doxorubicin fluorescence correlated with decreasing fluorescence of the DNA-binding stain Hoechst 33342, and based on the quantified intracellular uptake of doxorubicin an apparent cell permeability (9.00 ± 0.74 x 10-4 µm/s for HepG2) was determined.
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| 4. |
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| 5. |
- Filipek-Gorniok, Beata, et al.
(författare)
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Expression of chondroitin/dermatan sulfate glycosyltransferases during early zebrafish development
- 2013
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Ingår i: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 242:8, s. 964-975
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Tidskriftsartikel (refereegranskat)abstract
- Background: Chondroitin/dermatan sulfate (CS/DS) proteoglycans present in the extracellular matrix have important structural and regulatory functions. Results: Six human genes have previously been shown to catalyze CS/DS polymerization. Here we show that one of these genes, chpf, is represented by two copies in the zebrafish genome, chpfa and chpfb, while the other five human CS/DS glycosyltransferases csgalnact1, csgalnact2, chpf2, chsy1, and chsy3 all have single zebrafish orthologues. The putative zebrafish CS/DS glycosyltransferases are spatially and temporally expressed. Interestingly, overlapping expression of multiple glycosyltransferases coincides with high CS/DS deposition. Finally, whereas the relative levels of the related polysaccharide HS reach steady-state at around 2 days post fertilization, there is a continued relative increase of the CS amounts per larvae during the first 6 days of development, matching the increased cartilage formation. Conclusions: There are 7 CS/DS glycosyltransferases in zebrafish, which, based on homology, can be divided into the CSGALNACT, CHSY, and CHPF families. The overlap between intense CS/DS production and the expression of multiple CS/DS glycosyltransferases suggests that efficient CS/DS biosynthesis requires a combination of several glycosyltransferases.
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| 6. |
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| 7. |
- Heldin, Johan, et al.
(författare)
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FGD5 sustains vascular endothelial growth factor A (VEGFA) signaling through inhibition of proteasome-mediated VEGF receptor 2 degradation
- 2017
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 40, s. 125-132
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Tidskriftsartikel (refereegranskat)abstract
- The complete repertoire of endothelial functions elicited by FGD5, a guanine nucleotide exchange factor activating the Rho GTPase Cdc42, has yet to be elucidated. Here we explore FGD5's importance during vascular endothelial growth factor A (VEGFA) signaling via VEGF receptor 2 (VEGFR2) in human endothelial cells. In microvascular endothelial cells, FGD5 is located at the inner surface of the cell membrane as well as at the outer surface of EEAl-positive endosomes carrying VEGFR2. The latter finding prompted us to explore if FGD5 regulates VEGFR2 dynamics. We found that depletion of FGD5 in microvascular cells inhibited their migration towards a stable VEGFA gradient. Furthermore, depletion of FGD5 resulted in accelerated VEGFR2 degradation, which was reverted by lactacystin-mediated proteasomal inhibition. Our results thus suggest a mechanism whereby FGD5 sustains VEGFA signaling and endothelial cell chemotaxis via inhibition of proteasome-dependent VEGFR2 degradation.
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| 8. |
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| 9. |
- Heldin, Johan
(författare)
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Identification and Characterization of Proteins and MicroRNAs that Modulate Receptor Signaling, Vesicular Trafficking and Cell Migration in Vascular Cells
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Blood vessels deliver nutrients and oxygen to tissues. Importantly, the functions and growth of blood vessels are commonly altered in disease. The inside of all blood vessels are lined with endothelium, a thin specialized layer of endothelial cells that separate the blood from other tissues. This thesis deals with the identification and functional characterization of proteins and microRNAs that have key roles as modulators of growth factor signaling and directed cell migration of endothelial cells and other vascular cells.A previously uncharacterized protein of the exocyst complex, Exocyst complex component 3-like 2 (ExoC3L2) was identified and shown to be highly expressed in endothelial cells of sprouting vessels. Suppression of ExoC3L2 resulted in reduced VEGF-A signaling together with reduced chemotaxis in response to VEGF-A gradients. VEGF-A-signaling via its receptor VEGFR-2 is thus modulated by the exocyst complex and ExoC3L2.Expression profiling of highly vascularized tissues were used to identify several microRNAs selectively expressed in blood vessels. miR-145, targeting the transcription factor Fli1, was shown to be expressed in pericytes and mural cells. Elevated levels of miR-145 reduced chemotaxis of both endothelial cells and fibroblasts in response to growth factor gradients. miR-145 depletion in fibroblasts was shown to inhibit chemotaxis in response to PDGF-BB.The guanine nucleotide exchange factor FGD5 was shown to be selectively expressed in endothelial cells and to regulate Cdc42 activity. FGD5 was shown to regulate the turnover of activated VEGF-receptors. Suppression of FGD5 impaired endothelial cell chemotaxis, suggesting that FGD5 is required for efficient and sustained VEGF-A signaling.Inactivation of RhoD, a regulator of endosomal trafficking, resulted in an increased pool of acetylated and stable microtubules. Knockdown of RhoD in human fibroblasts resulted in a loss of cell polarity. A link between PDGFR-β and RhoD was implicated by the finding that PDGF-BB was shown to trigger formation of GTP-bound RhoD. Chemotaxis towards PDGF-BB was severely inhibited in cells with reduced RhoD expression, suggesting a role for RhoD in chemotaxis via its regulation of microtubule dynamics.
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| 10. |
- Holmborn, Katarina, et al.
(författare)
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On the Roles and Regulation of Chondroitin Sulfate and Heparan Sulfate in Zebrafish Pharyngeal Cartilage Morphogenesis
- 2012
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287:40, s. 33905-33916
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Tidskriftsartikel (refereegranskat)abstract
- The present study addresses the roles of heparan sulfate (HS) proteoglycans and chondroitin sulfate (CS) proteoglycans in the development of zebrafish pharyngeal cartilage structures. uxs1 and b3gat3 mutants, predicted to have impaired biosynthesis of both HS and CS because of defective formation of the common proteoglycan linkage tetrasaccharide were analyzed along with ext2 and extl3 mutants, predicted to have defective HS polymerization. Notably, the effects on HS and CS biosynthesis in the respective mutant strains were shown to differ from what had been hypothesized. In uxs1 and b3gat3 mutant larvae, biosynthesis of CS was shown to be virtually abolished, whereas these mutants still were capable of synthesizing 50% of the HS produced in control larvae. extl3 and ext2 mutants on the other hand were shown to synthesize reduced amounts of hypersulfated HS. Further, extl3 mutants produced higher levels of CS than control larvae, whereas morpholino-mediated suppression of csgalnact1/csgalnact2 resulted in increased HS biosynthesis. Thus, the balance of the Extl3 and Csgalnact1/Csgalnact2 proteins influences the HS/CS ratio. A characterization of the pharyngeal cartilage element morphologies in the single mutant strains, as well as in ext2;uxs1 double mutants, was conducted. A correlation between HS and CS production and phenotypes was found, such that impaired HS biosynthesis was shown to affect chondrocyte intercalation, whereas impaired CS biosynthesis inhibited formation of the extracellular matrix surrounding chondrocytes.
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