Rab-genome analysis reveals novel insights in Weibel-Palade body exocytosis

Zografou, Sofia; Basagiannis, Dimitris; Papafotika, Alexandra; Shirakawa, Ryutaro; Horiuchi, Hisanori; Auerbach, Daniel; Fukuda, Mitsunori; Christoforidis, Savvas

doi:10.1242/jcs.104174

Cited by 79 publications

(105 citation statements)

References 77 publications

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“…Their experiments further showed that Munc13-4, an already known effector of Rab27a, colocalized with Rab15 at WPBs. Taken together, this information suggests that the three proteins Rab27a, Rab15, and Munc13-4 likely work in tandem to help regulate exocytosis of vWF (Zografou et al, 2012). -CaM further binds to the amino terminus of Ral GDS, which leads to the dissociation from the inhibitory beta-arrestin and to activation of RalA.…”

Section: A Components Of Exocytosis Signaling Microdomainsmentioning

confidence: 93%

“…Rab proteins found in association with the WPBs are Rab3b Rab3d (Knop et al, 2004), Rab27a (Hannah et al, 2003), Rab3a, Rab15, Rab33a, and Rab37 (Zografou et al, 2012). Rab27a can either inhibit the secretion of WPBs by associating with its effector MyRIP (myosin VIIA and Rab interacting protein), thus anchoring WPBs to actin filaments and keeping them from attaching to the plasma membrane (Nightingale et al, 2009) or activate the secretion of WPBs by associating with an alternate effector, Slp4-a (synaptotagmin-like protein 4), which links the secretory granules to the plasma membrane (Gomi et al, 2005).…”

Section: A Components Of Exocytosis Signaling Microdomainsmentioning

confidence: 99%

“…Rab27a is central to the process of vesicle secretion, because the ratio of fractional occupancy of Rab27a by Slp4-a and MyRIP plays a role in determining the balance for or against exocytosis . Furthermore, Rab27a may work in conjunction with Rab15 to help control exocytosis; Zografou et al (2012) recently showed that simultaneous knockdown of the two Rabs using siRNA in HUVECs leads to a greater reduction in vWF secretion compared with knockdown of either Rab individually. Their experiments further showed that Munc13-4, an already known effector of Rab27a, colocalized with Rab15 at WPBs.…”

Section: A Components Of Exocytosis Signaling Microdomainsmentioning

confidence: 99%

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Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall

et al. 2014

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Section: A Components Of Exocytosis Signaling Microdomainsmentioning

confidence: 93%

Section: A Components Of Exocytosis Signaling Microdomainsmentioning

confidence: 99%

Section: A Components Of Exocytosis Signaling Microdomainsmentioning

confidence: 99%

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Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall

et al. 2014

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“…Culture of Endothelial Cells, Transfections, InfectionsHUVECs were isolated, cultured, and transfected or infected as described previously (66). Bovine retinal endothelial cells (obtained from VEC Technologies) were cultured on fibronectin-coated dishes, in DMEM supplemented with 10% fetal bovine serum, 4.5 g/liter of glucose, 1% penicillin, 1% streptomycin, 2 mmol/liter of L-glutamine, 25 mmol/liter of Hepes, 20 g/ml of endothelial cell growth supplement, and 50 g/ml of heparin.…”

Section: Methodsmentioning

confidence: 99%

Constitutive Endocytosis of VEGFR2 Protects the Receptor against Shedding

Basagiannis

Christoforidis

2016

Journal of Biological Chemistry

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VEGFR2 plays a fundamental role in blood vessel formation and in life threatening diseases, such as cancer angiogenesis and cardiovascular disorders. Although inactive growth factor receptors are mainly localized at the plasma membrane, VEGFR2 undergoes constitutive endocytosis (in the absence of ligand) and recycling. Intriguingly, the significance of these futile transport cycles of VEGFR2 remains unclear. Here we found that, unexpectedly, the function of constitutive endocytosis of VEGFR2 is to protect the receptor against plasma membrane cleavage (shedding), thereby preserving the functional state of the receptor until the time of activation by VEGF. Inhibition of constitutive endocytosis of VEGFR2, by interference with the function of clathrin, dynamin, or Rab5, increases dramatically the cleavage/shedding of VEGFR2. Shedding of VEGFR2 produces an N-terminal soluble fragment (100 kDa, s100), which is released in the extracellular space, and a residual C-terminal part (130 kDa, p130) that remains integrated at the plasma membrane. The released soluble fragment (s100) co-immunoprecipitates with VEGF, in line with the topology of the VEGF-binding domain at the N terminus of VEGFR2. Increased shedding of VEGFR2 (via inhibition of constitutive endocytosis) results in reduced response to VEGF, consistently with the loss of the VEGF-binding domain from the membrane remnant of VEGFR2. These data suggest that constitutive internalization of VEGFR2 protects the receptor against shedding and provides evidence for an unprecedented mechanism via which endocytosis can regulate the fate and activity of growth factor receptors.Growth factor receptors are synthesized and processed in the ER/Golgi biosynthetic network. Subsequently, they are delivered to the plasma membrane to become available for binding to their extracellular cognate ligands. In principle, in the absence of ligand, quiescent receptors are preferentially localized at the plasma membrane, whereas only a small percentage of the surface molecules are constitutively internalized (1-3). On the other hand, ligand binding and subsequent receptor activation increases dramatically the efficiency of receptor internalization (3, 4). Internalized receptors explore the different endocytic itineraries and the diverse endocytic compartments to finetune the intensity, nature, and duration of the signaling events (2, 4, 5). Subsequently, growth factor receptors are either recycled back to plasma membrane, for another round of activation, or they are sorted to lysosomes or the proteasome for degradation, leading to irreversible termination of the receptor function (6). In fact, in general, the degradative role of endocytosis is considered to be one of the major housekeeping functions of the cell that eventually down-regulates the levels of the internalized, extracellular or plasma membrane, molecules (7-9).VEGFR2 is a receptor-tyrosine kinase that plays a critical role in blood vessel formation and pathological angiogenesis (10,11). Similarly to other receptor-tyrosine kinas...

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“…HUVECs were isolated, cultured and transfected as previously described (Zografou et al, 2012). Cells were routinely tested for contamination.…”

Section: Cell Treatmentsmentioning

confidence: 99%

VEGF induces signalling and angiogenesis by directing VEGFR2 internalisation through macropinocytosis

Basagiannis¹,

Zografou²,

Murphy³

et al. 2016

Development

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Endocytosis plays a crucial role in receptor signalling. VEGFR2 (also known as KDR) and its ligand VEGFA are fundamental in neovascularisation. However, our understanding of the role of endocytosis in VEGFR2 signalling remains limited. Despite the existence of diverse internalisation routes, the only known endocytic pathway for VEGFR2 is the clathrin-mediated pathway. Here, we show that this pathway is the predominant internalisation route for VEGFR2 only in the absence of ligand. Intriguingly, VEGFA induces a new internalisation itinerary for VEGFR2, the pathway of macropinocytosis, which becomes the prevalent endocytic route for the receptor in the presence of ligand, whereas the contribution of the clathrin-mediated route becomes minor. Macropinocytic internalisation of VEGFR2, which mechanistically is mediated through the small GTPase CDC42, takes place through macropinosomes generated at ruffling areas of the membrane. Interestingly, macropinocytosis plays a crucial role in VEGFAinduced signalling, endothelial cell functions in vitro and angiogenesis in vivo, whereas clathrin-mediated endocytosis is not essential for VEGFA signalling. These findings expand our knowledge on the endocytic pathways of VEGFR2 and suggest that VEGFA-driven internalisation of VEGFR2 through macropinocytosis is essential for endothelial cell signalling and angiogenesis.

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Rab-genome analysis reveals novel insights in Weibel-Palade body exocytosis

Cited by 79 publications

References 77 publications

Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall

Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall

Constitutive Endocytosis of VEGFR2 Protects the Receptor against Shedding

VEGF induces signalling and angiogenesis by directing VEGFR2 internalisation through macropinocytosis

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