Ras Family GTPases Control Growth of Astrocyte Processes

Kalman, Daniel; Gomperts, Stephen N.; Hardy, Simon; Kitamura, Marina; Bishop, J. Michael

doi:10.1091/mbc.10.5.1665

Cited by 64 publications

(60 citation statements)

References 47 publications

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“…Human brain microvascular endothelial cells (HBMECs, gift of Dr. Kwang Sik Kim, Johns Hopkins University) were cultured essentially as HUVECs. For adenoviral transduction, cells were infected with adenoviral particles carrying various cDNA constructs for 12 h prior to stimulation with S1P as previously described (18,19).…”

Section: Methodsmentioning

confidence: 99%

“…f , in a parallel experiment, endothelial cells were transduced with 200 moi of adenoviral particles as described in panel d. 500 g of cell extracts were immunoprecipitated with anti-S1P1, followed by immunoblotting with anti-S1P1 (top panel). Alternatively, 50 g of extracts were immunoblotted with anti-Akt or anti-Myc to show the expression of transduced polypeptides (middle and lower panels) (18,19). Left lane, without endothelial extracts.…”

Section: Methodsmentioning

confidence: 99%

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Dual Roles of Tight Junction-associated Protein, Zonula Occludens-1, in Sphingosine 1-Phosphate-mediated Endothelial Chemotaxis and Barrier Integrity

Lee

Zeng

Ozaki³

et al. 2006

Journal of Biological Chemistry

161

169

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In this report, sphingosine-1-phosphate (S1P), a serum-borne bioactive lipid, is shown to activate tight-junction-associated protein Zonula Occludens-1 (ZO-1), which in turn plays a critical role in regulating endothelial chemotaxis and barrier integrity. After S1P stimulation, ZO-1 was redistributed to the lamellipodia and cell-cell junctions via the S1P1/G i /Akt/Rac pathway. Similarly, both endothelial barrier integrity and cell motility were significantly enhanced in S1P-treated cells through the G i /Akt/Rac pathway. Importantly, S1P-enhanced barrier integrity and cell migration were abrogated in ZO-1 knockdown cells, indicating ZO-1 is functionally indispensable for these processes. To investigate the underlying mechanisms, we demonstrated that cortactin plays a critical role in S1P-induced ZO-1 redistribution to the lamellipodia. In addition, S1P significantly induced the formation of endothelial tight junctions. ZO-1 and ␣-catenin polypeptides were colocalized in S1P-induced junctional structures; whereas, cortactin was not observed in these regions. Together, these results suggest that S1P induces the formation of two distinct ZO-1 complexes to regulate two different endothelial functions: ZO-1/cortactin complexes to regulate chemotactic response and ZO-1/␣-catenin complexes to regulate endothelial barrier integrity. The concerted operation of these two ZO-1 complexes may coordinate two important S1P-mediated functions, i.e. migration and barrier integrity, in vascular endothelial cells.Endothelial barrier integrity is an important physiological function of the endothelium in vivo. Dysregulated barrier integrity is implicated in a variety of pathological conditions, such as stroke, inflammation, various immune responses, etc. (1). To elucidate the function and regulation of endothelial barrier integrity, cultured brain microvascular endothelial cells have been widely employed as an in vitro model system to study the blood-brain barrier (BBB) 2 (2). Evidence from these studies indicates that BBB plays a critical role in regulating the homeostatic environment of the brain and the transportation of plasma constituents into brain. Furthermore, it has been shown that severely impaired blood-brain barrier integrity is attributed to the pathological states of various neurological disorders, such as multiple sclerosis (3, 4), Alzheimer disease (5, 6), and human immunodeficiency virus-1-associated encephalitis or dementia (7,8).Sphingosine 1-phosphate (S1P), a serum-borne bioactive lipid mediator secreted by activated platelets (9), enhances barrier formation in cultured pulmonary endothelial cells (ECs) (10). However, the molecular details for the formation and maintenance of endothelial barrier integrity are poorly understood. It was recently reported that the association of cortactin, an F-actin cross-linking polypeptide, and myosin light chain kinase is crucial in S1P-enhanced endothelial barrier integrity (11). Furthermore, it is well documented that tight junctions are important in regulating BBB formation...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Dual Roles of Tight Junction-associated Protein, Zonula Occludens-1, in Sphingosine 1-Phosphate-mediated Endothelial Chemotaxis and Barrier Integrity

Lee

Zeng

Ozaki³

et al. 2006

Journal of Biological Chemistry

161

169

View full text Add to dashboard Cite

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“…Adenovirus expressing Myc-tagged Rac1 dominant negative (Rac1-DN) under control of tetracycline repressor elements and a minimal cytomegalovirus promoter (tet-mCMV), and adenovirus constitutively expressing a tetracycline represor-Vp16 fusion protein, which was required to activate expression of the tet-mCMV were generated as described previously (29). HUVECs or BAECs were infected with adenovirus (m.o.i.…”

Section: Methodsmentioning

confidence: 99%

Akt Down-regulation of p38 Signaling Provides a Novel Mechanism of Vascular Endothelial Growth Factor-mediated Cytoprotection in Endothelial Cells

Gratton¹,

Morales-Ruíz²,

Kureishi³

et al. 2001

Journal of Biological Chemistry

259

184

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Vascular endothelial growth factor (VEGF) utilizes a phosphoinositide 3-kinase (PI 3-kinase)/Akt signaling pathway to protect endothelial cells from apoptotic death. Here we show that PI 3-kinase/Akt signaling promotes endothelial cell survival by inhibiting p38 mitogen-activated protein kinase (MAPK)-dependent apoptosis. Blockade of the PI 3-kinase or Akt pathways in conjunction with serum withdrawal stimulates p38-dependent apoptosis. Blockade of PI 3-kinase/Akt also led to enhanced VEGF activation of p38 and apoptosis. In this context, the pro-apoptotic effect of VEGF is attenuated by the p38 MAPK inhibitor SB203580. VEGF stimulation of endothelial cells or infection with an adenovirus expressing constitutively active Akt causes MEKK3 phosphorylation, which is associated with decreased MEKK3 kinase activity and down-regulation of MKK3/6 and p38 MAPK activation. Conversely, activation-deficient Akt decreases VEGF-stimulated MEKK3 phosphorylation and increases MKK/p38 activation. Activation of MKK3/6 is not dependent on Rac activation since dominant negative Rac does not decrease p38 activation triggered by inhibition of PI 3-kinase. Thus, cross-talk between the Akt and p38 MAPK pathways may regulate the level of cytoprotection versus apoptosis and is a new mechanism to explain the cytoprotective actions of Akt.

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“…mRNA, microarray analysis; X, not present in array chip or transcripts below reliable detection threshold; IB, proteins validated by immunoblotting in Fig. 4. RAC1 signaling is important for myelin sheath formation (19) and growth of astrocytic processes (20).…”

Section: Protein Identification By Sequential 1-dimensional Page and mentioning

confidence: 99%

Human myelin proteome and comparative analysis with mouse myelin

Ishii¹,

Dutta

Wark³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

106

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Myelin, formed by oligodendrocytes (OLs) in the CNS, is critical for axonal functions, and its damage leads to debilitating neurological disorders such as multiple sclerosis. Understanding the molecular mechanisms of myelination and the pathogenesis of human myelin disease has been limited partly by the relative lack of identification and functional characterization of the repertoire of human myelin proteins. Here, we present a large-scale analysis of the myelin proteome, using the shotgun approach of 1-dimensional PAGE and liquid chromatography/tandem MS. Three hundred eight proteins were commonly identified from human and mouse myelin fractions. Comparative microarray analysis of human white and gray matter showed that transcripts of several of these were elevated in OL-rich white matter compared with gray matter, providing confidence in their detection in myelin. Comparison with other databases showed that 111 of the identified proteins/transcripts also were expressed in OLs, rather than in astrocytes or neurons. Comparison with 4 previous myelin proteomes further confirmed more than 50% of the identified proteins and revealed the presence of 163 additional proteins. A select group of identified proteins also were verified by immunoblotting. We classified the identified proteins into biological subgroups and discussed their relevance in myelin biogenesis and maintenance. Taken together, the study provides insights into the complexity of this metabolically active membrane and creates a valuable resource for future in-depth study of specific proteins in myelin with relevance to human demyelinating diseases.microarray ͉ oligodendrocyte ͉ proteomics ͉ mass spectrometry

show abstract

Ras Family GTPases Control Growth of Astrocyte Processes

Cited by 64 publications

References 47 publications

Dual Roles of Tight Junction-associated Protein, Zonula Occludens-1, in Sphingosine 1-Phosphate-mediated Endothelial Chemotaxis and Barrier Integrity

Dual Roles of Tight Junction-associated Protein, Zonula Occludens-1, in Sphingosine 1-Phosphate-mediated Endothelial Chemotaxis and Barrier Integrity

Akt Down-regulation of p38 Signaling Provides a Novel Mechanism of Vascular Endothelial Growth Factor-mediated Cytoprotection in Endothelial Cells

Human myelin proteome and comparative analysis with mouse myelin

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