Connexin 43 gap junctions contribute to brain endothelial barrier hyperpermeability in familial cerebral cavernous malformations type III by modulating tight junction structure

• Published in: The FASEB journal Vol. 32; no. 5; p. 2615
• Main Authors: Johnson, Allison M, Roach, James P, Hu, Anna, Stamatovic, Svetlana M, Zochowski, Michal R, Keep, Richard F, Andjelkovic, Anuska V
• Format: Journal Article
• Language: English
• Published: United States 01.05.2018
• Subjects: Animals; Blood-Brain Barrier - metabolism; Blood-Brain Barrier - pathology; Cell Line; Claudin-5 - genetics; Claudin-5 - metabolism; Connexin 43 - genetics; Connexin 43 - metabolism; Disease Models, Animal; Endothelium, Vascular - metabolism; Endothelium, Vascular - pathology; Gap Junctions - genetics; Gap Junctions - metabolism; Gap Junctions - pathology; Hemangioma, Cavernous, Central Nervous System - genetics; Hemangioma, Cavernous, Central Nervous System - metabolism; Hemangioma, Cavernous, Central Nervous System - pathology; Humans; Mice; Mice, Knockout; Permeability; Tight Junctions - genetics; Tight Junctions - metabolism; Zonula Occludens-1 Protein - genetics; Zonula Occludens-1 Protein - metabolism; zonula occludens-1; PDCD10; cell-cell interaction; permeability
• ISSN: 1530-6860
• DOI: 10.1096/fj.201700699R

Familial cerebral cavernous malformations type III (fCCM3) is a disease of the cerebrovascular system caused by loss-of-function mutations in ccm3 that result in dilated capillary beds that are susceptible to hemorrhage. Before hemorrhage, fCCM3 lesions are characterized by a hyperpermeable blood-brain barrier (BBB), the key pathologic feature of fCCM3. We demonstrate that connexin 43 (Cx43), a gap junction (GJ) protein that is incorporated into the BBB junction complex, is up-regulated in lesions of a murine model of fCCM3. Small interfering RNA-mediated ccm3 knockdown (CCM3KD) in brain endothelial cells in vitro increased Cx43 protein expression, GJ plaque size, GJ intracellular communication (GJIC), and barrier permeability. CCM3KD hyperpermeability was rescued by GAP27, a peptide gap junction and hemichannel inhibitor of Cx43 GJIC. Tight junction (TJ) protein, zonula occludens 1 (ZO-1), accumulated at Cx43 GJs in CCM3KD cells and displayed fragmented staining at TJs. The GAP27-mediated inhibition of Cx43 GJs in CCM3KD cells restored ZO-1 to TJ structures and reduced plaque accumulation at Cx43 GJs. The TJ protein, Claudin-5, was also fragmented at TJs in CCM3KD cells, and GAP27 treatment lengthened TJ-associated fragments and increased Claudin 5-Claudin 5 transinteraction. Overall, we demonstrate that Cx43 GJs are aberrantly increased in fCCM3 and regulate barrier permeability by a TJ-dependent mechanism.-Johnson, A. M., Roach, J. P., Hu, A., Stamatovic, S. M., Zochowski, M. R., Keep, R. F., Andjelkovic, A. V. Connexin 43 gap junctions contribute to brain endothelial barrier hyperpermeability in familial cerebral cavernous malformations type III by modulating tight junction structure.