Naokazu Inoue
Fukushima Medical University
Molecular biologySpermBiologyHuman fertilizationCell biology
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Publications 51
Sperm–egg fusion is accomplished through the interaction of a specific set of membrane proteins in each gamete: sperm IZUMO1 and oocyte JUNO. Recently, we found that alternative splicing of the Izumo1 gene generates a novel IZUMO1 isoform (IZUMO1_v2). Here, we obtained four mouse lines, having graded different levels of IZUMO1 protein by combining an original IZUMO1 (IZUMO1_v1) knockout with IZUMO1-null (both IZUMO1_v1 and _v2 disrupted) genetic background, in order to determine how the quantity...
#1Takako Saito (Fukushima Medical University)H-Index: 1
#2Ikuo Wada (Fukushima Medical University)H-Index: 37
Last. Naokazu Inoue (Fukushima Medical University)H-Index: 25
view all 3 authors...
IZUMO1 is a sperm acrosomal membrane protein that is essential for mammalian fertilization through recognition of JUNO on the oocyte surface and accompanying IZUMO1-JUNO complex formation. Here, we report a new Izumo1 gene splicing variant (IZUMO1_v2) with a unique 52-amino-acid-long signal sequence transcribed from Exon 1b. Although the mRNA amount of Izumo1_v2 is 76 times lower than that of the original Izumo1 (IZUMO1_v1) in the testis, the cell-oocyte assay indicates that IZUMO1_v2-expressing...
1 CitationsSource
#1Naokazu Inoue (Fukushima Medical University)H-Index: 25
#2Ikuo Wada (Fukushima Medical University)H-Index: 37
ABSTRACTThe acrosome reaction (AR) is indispensable for successful spermatozoon-oocyte fusion. Recent studies have indicated that sperm IZUMO1 gradually gathers in the equatorial segment (EQ), which is the initiation site of sperm-egg fusion, after the AR. In addition, by examining the binding process of oocytes and Izumo1-expressing cultured cells to reconstitute the early steps of fertilization, we previously demonstrated that robust IZUMO1-dependent adhesion specifically occurs at the contact...
5 CitationsSource
#2Yuki TajikaH-Index: 16
Last. Hiroshi YorifujiH-Index: 14
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BACKGROUND: Vesicle-associated membrane protein 5 (VAMP5) is a member of the SNARE protein family, which regulates the docking and fusion of membrane vesicles within cells. Previously, we reported ubiquitous expression of VAMP5 proteins in various organs except the brain and small intestine. However, the precise roles of VAMP5 in each organ remain unclear. To explore the roles of VAMP5 in vivo, we generated VAMP5 knockout (KO) mice. RESULTS: VAMP5 KO mice showed low birth rate and low body weigh...
#1Naokazu Inoue (Fukushima Medical University)H-Index: 25
When a spermatozoon fertilizes an oocyte in mammals, there must be an extremely precise regulation system for successful gamete fusion to occur, which is the final step of fertilization. Using gene-modified animals, IZUMO1 on the sperm side and its receptor, JUNO, on the ovum side, have been unveiled as indispensable factors for triggering membrane fusion. We recently analyzed the detailed molecular machinery of the IZUMO1–JUNO recognition system and clarified the tertiary architecture of the IZ...
4 CitationsSource
#1Takuya Ishikawa (Nagoya University)H-Index: 10
#2Yasuyuki Kitaura (Nagoya University)H-Index: 18
Last. Yoshiharu Shimomura (Nagoya University)H-Index: 33
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Muscle-specific deletion of BDK amplifies loss of myofibrillar protein during protein undernutrition
6 CitationsSource
#1Umeharu OhtoH-Index: 25
#2Hanako IshidaH-Index: 5
Last. Toshiyuki ShimizuH-Index: 39
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The structure of the IZUMO1–JUNO complex, crucial for sperm–oocyte interaction during fertilization, is reported, providing a first step towards understanding the mechanics of the interaction.
35 CitationsSource
#1Naokazu Inoue (Fukushima Medical University)H-Index: 25
#2Yoshihisa Hagihara (AIST: National Institute of Advanced Industrial Science and Technology)H-Index: 31
Last. Ikuo Wada (Fukushima Medical University)H-Index: 37
view all 5 authors...
Sperm–egg fusion is indispensable for completing mammalian fertilization. Although the underlying molecular mechanisms are poorly understood, requirement of two spermatozoon factors, IZUMO1 and SPACA6, and two oocyte factors, CD9 and the IZUMO1 counter-receptor JUNO, has been proven by gene disruption, and the binding of cells to an oocyte can be reconstituted by ectopic expression of IZUMO1. Here we demonstrate that robust IZUMO1-dependent adhesion of sperm with an oocyte accompanies the dimeri...
35 CitationsSource
#1Nobuo Miyazaki (Kadai: Kagoshima University)H-Index: 2
#2Norihiko Kiyose (Kadai: Kagoshima University)H-Index: 2
Last. Yuji Ito (Kadai: Kagoshima University)H-Index: 15
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: The antigen-binding domain of camelid dimeric heavy chain antibodies, known as VHH or Nanobody, has much potential in pharmaceutical and industrial applications. To establish the isolation process of antigen-specific VHH, a VHH phage library was constructed with a diversity of 8.4 × 10(7) from cDNA of peripheral blood mononuclear cells of an alpaca (Lama pacos) immunized with a fragment of IZUMO1 (IZUMO1PFF) as a model antigen. By conventional biopanning, 13 antigen-specific VHHs were isolated...
11 CitationsSource
#1Tomohiko Matsuo (Osaka Bioscience Institute)H-Index: 2
#2Tatsuya Hattori (Azabu University)H-Index: 6
Last. Ko Kobayakawa (Osaka Bioscience Institute)H-Index: 10
view all 8 authors...
Most mammals have two major olfactory subsystems: the main olfactory system (MOS) and vomeronasal system (VNS). It is now widely accepted that the range of pheromones that control social behaviors are processed by both the VNS and the MOS. However, the functional contributions of each subsystem in social behavior remain unclear. To genetically dissociate the MOS and VNS functions, we established two conditional knockout mouse lines that led to either loss-of-function in the entire MOS or in the ...
36 CitationsSource