| 1. |
- Alvarez, Alberto, et al.
(författare)
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Cdc42 is required in mural cells for proper patterning of the retinal vasculature
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Mural cells constitute the outer lining of blood vessels. They are known as pericytes in the capillary network and referred to as smooth muscle cells (SMC) around arteries and veins. Despite their ubiquity, their contribution to vascular morphogenesis remains obscure. In this work, we investigated the role of Cdc42 in mural cells in vivo, using the developing mouse retina as a model. We find that, during postnatal development, Cdc42 is required in both, pericytes and smooth muscle cells to maintain proper cell morphology, coverage and distribution. During retinal angiogenesis, Cdc42-depleted pericytes lag behind the sprouting front, at least in part due to decreased proliferation. Consequently, capillaries at the sprouting front remain pericyte deprived and are prone to increased vascular leakage. In addition, arteries and arterioles deviate from their normal growth directions and trajectory. While in the adult retina, mural cell coverage normalizes and pericytes adopt a normal morphology, smooth muscle cell morphologies remain abnormal and arteriolar branching angles are markedly reduced. Our findings demonstrate that Cdc42 is required for mural cell proliferation, morphology and distribution and suggest that mural cells are essential for normal vascular morphogenesis of the developing retinal vasculature.
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| 2. |
- Brakebusch, Cord, et al.
(författare)
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Beta1 integrin is not essential for hematopoiesis but is necessary for the T cell-dependent IgM antibody response.
- 2002
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Ingår i: Immunity. - 1074-7613. ; 16:3, s. 465-477
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Tidskriftsartikel (refereegranskat)abstract
- Several experimental evidences suggested that beta1 integrin-mediated adhesion of hematopoietic stem cells (HSC) is important for their function in the bone marrow (BM). Using induced deletion of the beta1 integrin gene restricted to the hematopoietic system, we show that beta1 integrin is not essential for HSC retention in the BM, hematopoiesis, and trafficking of lymphocytes. However, immunization with a T cell-dependent antigen resulted in virtually no IgM production and an increased secretion of IgG in mutant mice, while the response to a T cell-independent type 2 antigen showed decreases in both IgM and IgG. These data suggest that beta1 integrins are necessary for the primary IgM antibody response.
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| 3. |
- Brakebusch, Cord, et al.
(författare)
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Brevican-deficient mice display impaired hippocampal CA1 long-term potentiation but show no obvious deficits in learning and memory
- 2002
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Ingår i: Molecular and Cellular Biology. - 0270-7306. ; 22:21, s. 7417-7427
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Tidskriftsartikel (refereegranskat)abstract
- Brevican is a brain-specific proteoglycan which is found in specialized extracellular matrix structures called perineuronal nets. Brevican increases the invasiveness of glioma cells in vivo and has been suggested to play a role in central nervous system fiber tract development. To study the role of brevican in the development and function of the brain, we generated mice lacking a functional brevican gene. These mice are viable and fertile and have a normal life span. Brain anatomy was normal, although alterations in the expression of neurocan were detected. Perineuronal nets formed but appeared to be less prominent in mutant than in wild-type mice. Brevican-deficient mice showed significant deficits in the maintenance of hippocampal long-term potentiation (LTP). However, no obvious impairment of excitatory and inhibitory synaptic transmission was found, suggesting a complex cause for the LTP defect. Detailed behavioral analysis revealed no statistically significant deficits in learning and memory. These data indicate that brevican is not crucial for brain development but has restricted structural and functional roles.
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| 4. |
- Brakebusch, Cord, et al.
(författare)
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Integrins in invasive growth.
- 2002
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Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 109:8, s. 999-1006
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Castro, Marco, et al.
(författare)
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CDC42 deletion elicits cerebral vascular malformations via increased MEKK3-dependent KLF4 expression
- 2019
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Ingår i: Circulation Research. - 0009-7330 .- 1524-4571. ; 124:8, s. 1240-1252
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Aberrant formation of blood vessels precedes a broad spectrum of vascular complications; however, the cellular and molecular events governing vascular malformations are not yet fully understood. Objective: Here, we investigated the role of CDC42 (cell division cycle 42) during vascular morphogenesis and its relative importance for the development of cerebrovascular malformations. Methods and Results: To avoid secondary systemic effects often associated with embryonic gene deletion, we generated an endothelial-specific and inducible knockout approach to study postnatal vascularization of the mouse brain. Postnatal endothelial-specific deletion of Cdc42 elicits cerebrovascular malformations reminiscent of cerebral cavernous malformations (CCMs). At the cellular level, loss of CDC42 function in brain endothelial cells (ECs) impairs their sprouting, branching morphogenesis, axial polarity, and normal dispersion within the brain tissue. Disruption of CDC42 does not alter EC proliferation, but malformations occur where EC proliferation is the most pronounced during brain development-the postnatal cerebellum-indicating that a high, naturally occurring EC proliferation provides a permissive state for the appearance of these malformations. Mechanistically, CDC42 depletion in ECs elicited increased MEKK3 (mitogen-activated protein kinase kinase kinase 3)-MEK5 (mitogen-activated protein kinase kinase 5)-ERK5 (extracellular signal-regulated kinase 5) signaling and consequent detrimental overexpression of KLF (Kruppel-like factor) 2 and KLF4, recapitulating the hallmark mechanism for CCM pathogenesis. Through genetic approaches, we demonstrate that the coinactivation of Klf4 reduces the severity of vascular malformations in Cdc42 mutant mice. Moreover, we show that CDC42 interacts with CCMs and that CCM3 promotes CDC42 activity in ECs. Conclusions: We show that endothelial-specific deletion of Cdc42 elicits CCM-like cerebrovascular malformations and that CDC42 is engaged in the CCM signaling network to restrain the MEKK3-MEK5-ERK5-KLF2/4 pathway.
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| 6. |
- Danen, EHJ, et al.
(författare)
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The fibronectin-binding integrins alpha 5 beta 1 and alpha v beta 3 differentially modulate RhoA-GTP loading, organization of cell matrix adhesions, and fibronectin fibrillogenesis
- 2002
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Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 159:6, s. 1071-1086
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the formation of different types of cell matrix adhesions in cells that bind to fibronectin via either alpha5beta1 or alphavbeta3. In both cases, cell adhesion to fibronectin leads to a rapid decrease in RhoA activity. However, alpha5beta1 but not alphavbeta3 supports high levels of RhoA activity at later stages of cell spreading, which are associated with a translocation of focal contacts to peripheral cell protrusions, recruitment of tensin into fibrillar adhesions, and fibronectin fibrillogenesis. Expression of an activated mutant of RhoA stimulates alphavbeta3-mediated fibrillogenesis. Despite the fact that alpha5beta1-mediated adhesion to the central cell-binding domain of fibronectin supports activation of RhoA, other regions of fibronectin are required for the development of alpha5beta1-mediated but not alphavbeta3-mediatecl focal contacts. Using chimeras of beta1 and beta3 subunits, we find that the extracellular domain of beta1 controls RhoA activity. By expressing both beta1 and beta3 at high levels, we show that beta1-mediated control of the levels of beta3 is important for the distribution of focal contacts. Our findings demonstrate that the pattern of fibronectin receptors expressed on a cell dictates the ability of fibronectin to stimulate RhoA-mediated organization of cell matrix adhesions.
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| 7. |
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| 8. |
- Grose, R, et al.
(författare)
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A crucial role of beta 1 integrins for keratinocyte migration in vitro and during cutaneous wound repair
- 2002
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Ingår i: Development: For advances in developmental biology and stem cells. - 1477-9129. ; 129:9, s. 2303-2315
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Tidskriftsartikel (refereegranskat)abstract
- Integrins are ubiquitous transmembrane receptors that play crucial roles in cell-cell and cell-matrix interactions. In this study, we have determined the effects of the loss of beta1 integrins in keratinocytes in vitro and during cutaneous wound repair. Flow cytometry of cultured beta1-deficient keratinocytes confirmed the absence of beta1 integrins and showed downregulation of alpha6beta4 but not of alphanu integrins. beta1-null keratinocytes were characterised by poor adhesion to various substrates, by a reduced proliferation rate and by a strongly impaired migratory capacity. In vivo, the loss of 01 integrins in keratinocytes caused a severe defect in wound healing. beta1-null keratinocytes showed impaired migration and were more densely packed in the hyperproliferative epithelium. Surprisingly, their proliferation rate was not reduced in early wounds and even increased in late wounds. The failure in re-epithelialisation resulted in a prolonged inflammatory response, leading to dramatic alterations in the expression of important wound-regulated genes. Ultimately, beta1-deficient epidermis did cover the wound bed, but the epithelial architecture was abnormal. These findings demonstrate a crucial role of beta1 integrins in keratinocyte migration and wound re-epithelialisation.
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| 9. |
- Gustavsson, Anna, et al.
(författare)
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Role of the β1-integrin cytoplasmic tail in mediating invasin-promoted internalization of Yersinia
- 2002
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Ingår i: Journal of Cell Science. - : The Company of Biologists Ltd. - 0021-9533 .- 1477-9137. ; 115:13, s. 2669-2678
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Tidskriftsartikel (refereegranskat)abstract
- Invasin of Yersinia pseudotuberculosis binds to beta1-integrins on host cells and triggers internalization of the bacterium. To elucidate the mechanism behind the beta1-integrin-mediated internalization of Yersinia, a beta1-integrin-deficient cell line, GD25, transfected with wild-type beta1A, beta1B or different mutants of the beta1A subunit was used. Both beta1A and beta1B bound to invasin-expressing bacteria, but only beta1A was able to mediate internalization of the bacteria. The cytoplasmic region of beta1A, differing from beta1B, contains two NPXY motifs surrounding a double threonine site. Exchanging the tyrosines of the two NPXYs to phenylalanines did not inhibit the uptake, whereas a marked reduction was seen when the first tyrosine (Y783) was exchanged to alanine. A similar reduction was seen when the two nearby threonines (TT788-9) were exchanged with alanines. It was also noted that cells affected in bacterial internalization exhibited reduced spreading capability when seeded onto invasin, suggesting a correlation between the internalization of invasin-expressing bacteria and invasin-induced spreading. Likewise, integrins defective in forming peripheral focal complex structures was unable to mediate uptake of invasin-expressing bacteria.
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| 10. |
- He, ZY, et al.
(författare)
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None of the integrins known to be present on the mouse egg or to be ADAM receptors are essential for sperm-egg binding and fusion
- 2003
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Ingår i: Developmental Biology. - 1095-564X. ; 254:2, s. 226-237
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Tidskriftsartikel (refereegranskat)abstract
- Antibody inhibition and alpha6beta1 ligand binding experiments indicate that the egg integrin alpha6beta1 functions as a receptor for sperm during gamete fusion; yet, eggs null for the alpha6 integrin exhibit normal fertilization. Alternative integrins may be involved in sperm-egg binding and fusion and could compensate for the absence of alpha6beta1. Various beta1 integrins and alphav integrins are present on mouse eggs. Some of these integrins are also reported to be receptors for ADAMs, which are expressed on sperm. Using alpha3 integrin null eggs, we found that the alpha3beta1 integrin was not essential for sperm-egg binding and fusion. Oocyte-specific, beta1 integrin conditional knockout mice allowed us to obtain mature eggs lacking all beta1 integrins. We found that the beta1 integrin null eggs were fully functional in fertilization both in vivo and in vitro. Furthermore, neither anti-mouse beta3 integrin function-blocking monoclonal antibody (mAb) nor alphav integrin function-blocking mAb inhibited sperm binding to or fusion with beta1 integrin null eggs. Thus, function of beta3 or alphav integrins does not seem to be involved in compensating for the absence of beta1 integrins. These results indicate that none of the integrins known to be present on mouse eggs or to be ADAM receptors are essential for sperm-egg binding/fusion, and thus, egg integrins may not play the role in gamete fusion previously attributed to them.
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