Junichi Ikenouchi
Kyushu University
Membrane lipidsBiophysicsActinMembrane proteinCellMolecular biologyTight junctionChemistryCytoplasmAdherens junctionBleb (cell biology)OccludinCell membraneCell junctionActin cytoskeletonApical membraneEpithelial polarityMembraneClaudinEpitheliumSphingomyelinBiologyCell biology
46Publications
21H-index
3,370Citations
Publications 37
Newest
#1Junichi Ikenouchi (Kyushu University)H-Index: 21
#2Kana Aoki (Kyushu University)H-Index: 4
When the plasma membrane (PM) detaches from the underlying actin cortex, the PM expands according to intracellular pressure and a spherical membrane protrusion called a bleb is formed. This bleb retracts when the actin cortex is reassembled underneath the PM. Whereas this phenomenon seems simple at first glance, there are many interesting, unresolved cell biological questions in each process. For example, what is the membrane source to enlarge the surface area of the PM during rapid bleb expansi...
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#1Kenji Matsuzawa (Kyushu University)H-Index: 2
#2Hayato Ohga (Kyushu University)H-Index: 1
Last. Junichi Ikenouchi (Kyushu University)H-Index: 21
view all 6 authors...
Constriction of the apical plasma membrane is a hallmark of epithelial cells that underlies cell shape changes in tissue morphogenesis and maintenance of tissue integrity in homeostasis. Contractile force is exerted by a cortical actomyosin network that is anchored to the plasma membrane by the apical junctional complexes (AJC). In this study, we present evidence that MAGI proteins, structural components of AJC whose function remained unclear, regulate apical constriction of epithelial cells thr...
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#1Kana Aoki (Kyushu University)H-Index: 4
#2Shota Harada (Kyushu University)H-Index: 4
Last. Junichi Ikenouchi (Kyushu University)H-Index: 21
view all 6 authors...
The cytoplasm in mammalian cells is considered homogeneous. In this study, we report that the cytoplasmic fluidity is regulated in the blebbing cells; the cytoplasm of rapidly expanding membrane blebs is more disordered than the cytoplasm of retracting blebs. The increase of cytoplasmic fluidity in the expanding bleb is caused by a sharp rise in the calcium concentration. The STIM-Orai1 pathway regulates this rapid and restricted increase of calcium in the expanding blebs. Conversely, activated ...
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#1Kana Aoki (Kyushu University)H-Index: 4
#2Shinsuke Satoi (Kyushu University)H-Index: 2
Last. Junichi Ikenouchi (Kyushu University)H-Index: 21
view all 6 authors...
Apoptotic cells form membrane blebs, but little is known about how the formation and dynamics of membrane blebs are regulated. The size of blebs gradually increases during the progression of apopto...
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#1Kenta Shigetomi (Kyushu University)H-Index: 6
#2Junichi Ikenouchi (Kyushu University)H-Index: 21
: There are many morphologically distinct membrane structures with different functions at the surface of epithelial cells. Among these, adherens junctions (AJ) and tight junctions (TJ) are responsible for the mechanical linkage of epithelial cells and epithelial barrier function, respectively. In the process of new cell-cell adhesion formation between two epithelial cells, such as after wounding, AJ form first and then TJ form on the apical side of AJ. This process is very complicated because AJ...
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#1Junichi Ikenouchi (Kyushu University)H-Index: 21
ABSTRACTEpithelial cells have characteristic membrane domains. Identification of membrane proteins playing an important role in these membrane domains has progressed and numerous studies have been performed on the functional analysis of these membrane proteins. On the other hand, the precise roles of membrane lipids in the organization of these membrane domains are largely unknown. Historically, the concept of lipid raft arose from the analysis of lipid composition of the apical membrane, and it...
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#1Kenta Shigetomi (Kyushu University)H-Index: 6
#2Yumiko Ono (Kyushu University)H-Index: 1
Last. Junichi Ikenouchi (Kyushu University)H-Index: 21
view all 4 authors...
Tight junctions (TJs) are essential cell adhesion structures that act as a barrier to separate the internal milieu from the external environment in multicellular organisms. Although their major constituents have been identified, it is unknown how the formation of TJs is regulated. TJ formation depends on the preceding formation of adherens junctions (AJs) in epithelial cells; however, the underlying mechanism remains to be elucidated. In this study, loss of AJs in α-catenin–knockout (KO) EpH4 ep...
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#1Kenji Matsuzawa (Kyushu University)H-Index: 2
#2Takuya Himoto (Kyushu University)H-Index: 1
Last. Junichi Ikenouchi (Kyushu University)H-Index: 21
view all 4 authors...
Summary Adherens junctions (AJs) control epithelial cell behavior, such as collective movement and morphological changes, during development and in disease. However, the molecular mechanism of AJ remodeling remains incompletely understood. Here, we report that the conformational activation of α-catenin is the key event in the dynamic regulation of AJ remodeling. α-catenin activates RhoA to increase actomyosin contractility at cell-cell junctions. This leads to the stabilization of activated α-ca...
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#1Masaki Tsuchiya (Kyoto University)H-Index: 3
#2Yuji Hara (Kyoto University)H-Index: 25
Last. Masato Umeda (Kyoto University)H-Index: 24
view all 21 authors...
Myotube formation by fusion of myoblasts and subsequent elongation of the syncytia is essential for skeletal muscle formation. However, molecules that regulate myotube formation remain elusive. Here we identify PIEZO1, a mechanosensitive Ca2+ channel, as a key regulator of myotube formation. During myotube formation, phosphatidylserine, a phospholipid that resides in the inner leaflet of the plasma membrane, is transiently exposed to cell surface and promotes myoblast fusion. We show that cell s...
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#1Kenta Shigetomi (Kyushu University)H-Index: 6
#2Junichi Ikenouchi (Kyushu University)H-Index: 21
: Body and organ surfaces in multicellular organisms are covered with a sheet of epithelial cells. The tight junction (TJ) is an adhesive structure that seals the gap between epithelial cells and functions as a selective barrier to prevent the entry of antigens and pathogenic microbes from the extracellular environment. Several transmembrane proteins that constitute the TJ (claudin, occludin, tricellulin and angulin) have been identified. As over-expression of these proteins does not enlarge TJs...
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