Abnormalities in caveolae and lung endothelial cell (ECs) function may result in alterations of lung vascular permeability. This may be a key element of the complex pathophysiology underlying acute lung injury. The understanding of the molecular mechanisms that regulate caveolae-mediated transcytosis and its role in mediating increased lung microvessel endothelial permeability are unclear. Our Supporting Data suggest that the crucial scaffold protein in lung ECs, intersectin-1s (ITSN-1s), plays an important role in caveolae trafficking through its interaction with dynamin and other key proteins regulating endothelial permeability. Our Supporting Data suggest that ITSN-1s is crucial in recruiting dynamin at the neck region of caveolae and that dynamin presence at the endocytic site and its ability to hydrolyze GTP are essential for caveolae release from the plasma membrane during caveolae transcytosis. However, the relationship between ITSN-1s and dynamin and its significance in the mechanism of increased lung vascular endothelial permeability are not yet defined. Strikingly, ECs deficient in ITSN-1s became apoptotic by activation of the mitochondrial death pathway through a mechanism that involves inactivation of the survival kinase Erk1/2. Thus, besides regulating transcytosis, ITSN-1s is also an anti-apoptotic protein that may have consequences in mediating lung microvascular injury secondary to apoptosis of ECs. The central hypothesis of the proposed studies is that ITSN-1s is a pivotal protein mediating the cross-talk between caveolae endocytosis and signaling pathways that regulates lung vascular endothelial permeability and EC survival. The following specific aims will test this hypothesis:
Specific Aim 1 will define the role of ITSN-1s, via its SH3 domains, as a regulator of dynamin function.
Specific Aim 2 will address the functional significance of ITSN-1s/dynamin interaction in the mechanism of caveolae release from the plasma membrane of lung microvessel ECs and in regulating lung microvascular permeability in mice.
Specific Aim 3 will delineate the signaling mechanisms controlled by ITSN-1s that defend lung endothelium against apoptotic cell death and lung vascular endothelial injury. With the successful completion of the aims, we hope to provide novel insights into the i) pivotal role of the SH3 domains of ITSN-1s in regulation of dynamin function in lung microvessel ECs, ii) functional significance of ITSN/dynamin interaction in caveolae endocytosis and lung endothelial barrier function, and iii) signaling pathways and mechanisms governing the anti-apoptotic effects of ITSN-1s in ECs and its pathophysiological consequence in the mechanism of lung microvascular injury. We hope to provide a novel understanding of transcytosis and its regulation of lung vascular endothelial permeability and specific molecular therapeutic targets directed against inappropriate leakiness of the lung microvascular barrier. This study will provide novel insights regarding i) the role of intersectin-1s in regulation of lung vascular endothelial permeability and ii) the signaling pathways and mechanisms governing the anti-apoptotic effects of intersectin-1s in endothelial cells. Confirming intersectin-1s as a link between microvascular permeability, apoptosis and lung disease, we may find new targets against inappropriate leakiness of the lung microvascular barrier and slow the alveolar destruction associated with acute respiratory distress syndrome (ARDS) and acute lung injury (ALI).

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Respiratory Integrative Biology and Translational Research Study Section (RIBT)
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Harabin, Andrea L
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Rush University Medical Center
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Patel, Monal; Predescu, Dan; Bardita, Cristina et al. (2017) Modulation of Intersectin-1s Lung Expression Induces Obliterative Remodeling and Severe Plexiform Arteriopathy in the Murine Pulmonary Vascular Bed. Am J Pathol 187:528-542
Jeganathan, Niranjan; Predescu, Dan; Zhang, Jin et al. (2016) Rac1-mediated cytoskeleton rearrangements induced by intersectin-1s deficiency promotes lung cancer cell proliferation, migration and metastasis. Mol Cancer 15:59
Bardita, Cristina; Predescu, Dan N; Sha, Fei et al. (2015) Endocytic deficiency induced by ITSN-1s knockdown alters the Smad2/3-Erk1/2 signaling balance downstream of Alk5. J Cell Sci 128:1528-41
Bardita, Cristina; Predescu, Dan; Justice, Matthew J et al. (2013) In vivo knockdown of intersectin-1s alters endothelial cell phenotype and causes microvascular remodeling in the mouse lungs. Apoptosis 18:57-76
Patel, Monal; Predescu, Dan; Tandon, Rajive et al. (2013) A novel p38 mitogen-activated protein kinase/Elk-1 transcription factor-dependent molecular mechanism underlying abnormal endothelial cell proliferation in plexogenic pulmonary arterial hypertension. J Biol Chem 288:25701-16
Bardita, Cristina; Predescu, Dan; Predescu, Sanda (2013) Long-term silencing of intersectin-1s in mouse lungs by repeated delivery of a specific siRNA via cationic liposomes. Evaluation of knockdown effects by electron microscopy. J Vis Exp :
Predescu, Dan N; Neamu, Radu; Bardita, Cristina et al. (2012) Impaired caveolae function and upregulation of alternative endocytic pathways induced by experimental modulation of intersectin-1s expression in mouse lung endothelium. Biochem Res Int 2012:672705
Knezevic, Ivana; Predescu, Dan; Bardita, Cristina et al. (2011) Regulation of dynamin-2 assembly-disassembly and function through the SH3A domain of intersectin-1s. J Cell Mol Med 15:2364-76
Singla, Sunit; Predescu, Dan; Bardita, Cristina et al. (2011) Pro-inflammatory endothelial cell dysfunction is associated with intersectin-1s down-regulation. Respir Res 12:46
Klein, Irene K; Predescu, Dan N; Sharma, Tiffany et al. (2009) Intersectin-2L regulates caveola endocytosis secondary to Cdc42-mediated actin polymerization. J Biol Chem 284:25953-61

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