ABSTRACT
The dynamic turnover of tight junctions (TJs) is essential for epithelial-mesenchymal transitions and/or mesenchymal-epithelial transitions during epithelial morphogenesis. We previously demonstrated that Rab13 specifically mediates the endocytic recycling of occludin. Here, we identified MICAL-L2 (molecule interacting with CasL-like 2) as a novel Rab13-binding protein. Immunoprecipitation and immunofluorescence microscopy showed that MICAL-L2 specifically bound to the GTP-bound form of Rab13 via its C terminus, which contained a coiled-coil domain, and localized at TJs in epithelial MTD-1A cells. Recycling assay demonstrated that a MICAL-L2 mutant lacking the Rab13-binding domain (MICAL-L2-N) specifically inhibited the endocytic recycling of occludin but not transferrin receptor. Ca2+ switch assay further revealed that MICAL-L2-N as well as Rab13 Q67L inhibited the recruitment of occludin to the plasma membrane, the development of transepithelial electrical resistance, and the formation of a paracellular diffusion barrier. MICAL-L2 was displaced from TJs upon actin depolymerization and was distributed along radiating actin cables and stress fibers in Ca2+-depleted MTD-1A and fibroblastic NIH3T3 cells, respectively. These results suggest that MICAL-L2 mediates the endocytic recycling of occludin and the formation of functional TJs by linking Rab13 to actin cytoskeleton. We rename MICAL-L2 as JRAB (junctional Rab13-binding protein).
Subject(s)
Cytoskeletal Proteins/metabolism , Endocytosis , Membrane Proteins/metabolism , rab GTP-Binding Proteins/metabolism , Actin Cytoskeleton/metabolism , Amino Acid Sequence , Animals , Calcium/metabolism , Cytoskeletal Proteins/analysis , Cytoskeletal Proteins/genetics , Dogs , Endocytosis/genetics , Epithelium/metabolism , Fibroblasts/metabolism , Mice , Microfilament Proteins , Molecular Sequence Data , Mutation , NIH 3T3 Cells , Occludin , Protein Structure, Tertiary , Tight Junctions/chemistry , Tight Junctions/metabolismABSTRACT
The authors carried out two studies to examine the effects of the 5-hydroxytryptamine receptor antagonist, sarpogrelate hydrochloride (SH), on flap necrosis. The first study measured survival rates and included histologic examination of random-pattern skin flaps in rabbits. The second study assessed the time to complete obstruction of blood flow with the artificial thrombus formation method, and the time for leukocytes to adhere to the endothelium of microvessels in a rabbit-ear chamber. The treatment groups were injected with SH. The survival rates of skin flaps in the SH-treated group were increased significantly. Histologic examination of vessels in the control group revealed that vessels in the deep dermis were obstructed completely by thrombi, whereas such vessels were not obstructed in the SH-treated group. Thrombus formation time and leukocyte adhesion time in the SH-treated group were prolonged and decreased, respectively. Thus, SH maintained flap circulation and promoted flap survival by preventing thrombus formation.
Subject(s)
Graft Survival/drug effects , Serotonin Antagonists/pharmacology , Succinates/pharmacology , Surgical Flaps , Thrombosis/prevention & control , Animals , Arterioles/drug effects , Arterioles/injuries , Arterioles/pathology , Cell Adhesion/drug effects , Ear/blood supply , Leukocytes/metabolism , Male , Microcirculation/drug effects , Rabbits , Vascular Patency/drug effects , Venules/drug effects , Venules/injuries , Venules/pathologyABSTRACT
BACKGROUND: Most cutaneous hemangiomas involute spontaneously. However, the lesion existing on the face poses a cosmetic problem during the waiting period for involution. METHODS: Hemangioma showing late involution was treated by local injection of monoethanolamine oleate solution. RESULTS: The lesion flattened and was excised serially. CONCLUSION: Sclerotherapy with monoethanolamine oleate can shorten the waiting period for involution and can decrease the risk of psychosocial trauma. Moreover, it provides good preparation for further surgery. Such sclerotherapy is effective in the treatment of hemangioma with late involution.