Mind bomb 1 is essential for generating functional Notch ligands to activate Notch |
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Authors: | Koo Bon-Kyoung Lim Hyoung-Soo Song Ran Yoon Mi-Jeong Yoon Ki-Jun Moon Jin-Sook Kim Young-Woong Kwon Min-Chul Yoo Kyeong-Won Kong Myung-Phil Lee Jinie Chitnis Ajay B Kim Cheol-Hee Kong Young-Yun |
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Institution: | Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784, South Korea. |
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Abstract: | The Delta-Notch signaling pathway is an evolutionarily conserved intercellular signaling mechanism essential for cell fate specification. Mind bomb 1 (Mib1) has been identified as a ubiquitin ligase that promotes the endocytosis of Delta. We now report that mice lacking Mib1 die prior to embryonic day 11.5, with pan-Notch defects in somitogenesis, neurogenesis, vasculogenesis and cardiogenesis. The Mib1-/- embryos exhibit reduced expression of Notch target genes Hes5, Hey1, Hey2 and Heyl, with the loss of N1icd generation. Interestingly, in the Mib1-/- mutants, Dll1 accumulated in the plasma membrane, while it was localized in the cytoplasm near the nucleus in the wild types, indicating that Mib1 is essential for the endocytosis of Notch ligand. In accordance with the pan-Notch defects in Mib1-/- embryos, Mib1 interacts with and regulates all of the Notch ligands, jagged 1 and jagged 2, as well as Dll1, Dll3 and Dll4. Our results show that Mib1 is an essential regulator, but not a potentiator, for generating functional Notch ligands to activate Notch signaling. |
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