Publishing type：Research paper (scientific journal)  

Diabetic neuropathy (DN) is a major complication of diabetes mellitus. Chondroitin sulfate (CS) is one of the most important extracellular matrix components and is known to interact with various diffusible factors; however, its role in DN pathology has not been examined. Therefore, we generated CSGalNAc-T1 knockout (T1KO) mice, in which CS levels were reduced. We demonstrated that diabetic T1KO mice were much more resistant to DN than diabetic wild-type (WT) mice. We also found that interactions between pericytes and vascular endothelial cells were more stable in T1KO mice. Among the RNA-seq results, we focused on the transforming growth factor β signaling pathway and found that the phosphorylation of Smad2/3 was less upregulated in T1KO mice than in WT mice under hyperglycemic conditions. Taken together, a reduction in CS level attenuates DN progression, indicating that CS is an important factor in DN pathogenesis.

DOI： 10.1016/j.isci.2024.109528

Scopus

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Fatty acids have long been considered essential to brain development; however, the involvement of their synthesis in nervous system formation is unclear. We generate mice with knockout of GPSN2, an enzyme for synthesis of very-long-chain fatty acids (VLCFAs) and investigate the effects. Both GPSN2-/- and GPSN2+/- mice show abnormal neuronal networks as a result of impaired neuronal polarity determination. Lipidomics of GPSN2-/- embryos reveal that ceramide synthesis is specifically inhibited depending on FA length; namely, VLCFA-containing ceramide is reduced. We demonstrate that lipid rafts are highly enriched in growth cones and that GPSN2+/- neurons lose gangliosides in their membranes. Application of C24:0 ceramide, but not C16:0 ceramide or C24:0 phosphatidylcholine, to GPSN2+/- neurons rescues both neuronal polarity determination and lipid-raft density in the growth cone. Taken together, our results indicate that VLCFA synthesis contributes to physiological neuronal development in brain network formation, in particular neuronal polarity determination through the formation of lipid rafts.

DOI： 10.1016/j.celrep.2023.113195

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

Phosphorylation is the most important post-translational modification of proteins in many cells, including neurons. Phosphoproteomics is a relatively new technique for comprehensively identifying phosphorylation sites in the whole proteome of a given system. We applied this method to developmental neurobiology research to understand the signaling pathways that regulate the mammalian growth cone, which is formed at the tips of developing neurites to ensure accurate neuronal network formation. Using this powerful technique, we identified at least four phosphorylation sites tightly associated with axon growth. Because phosphoproteomic results include relatively large numbers of phosphopeptides, the data are typically analyzed using bioinformatics. We utilized three bioinformatics tools to identify the responsible protein kinases, the putative functions of the phosphorylated protein groups, and the evolutional aspects of the phosphorylated proteins. Collectively, these data indicate phosphoproteomics is a cutting-edge tool for neuroscience research.

DOI： 10.1016/j.jneumeth.2020.108723

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

Neuronal polarization and growth are developmental processes that occur during neuronal cell differentiation. The molecular signaling mechanisms involved in these events in in vivo mammalian brain remain unclear. Also, cellular events of the neuronal polarization process within a given neuron are thought to be constituted of many independent intracellular signal transduction pathways (the "tug-of-war" model). However, in vivo results suggest that such pathways should be cooperative with one another among a given group of neurons in a region of the brain. Lipid rafts, specific membrane domains with low fluidity, are candidates for the hotspots of such intracellular signaling. Among the signals reported to be involved in polarization, a number are thought to be present or translocated to the lipid rafts in response to extracellular signals. As part of our analysis, we discuss how such novel molecular mechanisms are combined for effective regulation of neuronal polarization and growth, focusing on the significance of the lipid rafts, including results based on recently introduced methods.

DOI： 10.3389/fnmol.2020.00150

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

The growth cone is a specialized structure that forms at the tip of extending axons in developing and regenerating neurons. This structure is essential for accurate synaptogenesis at developmental stages, and is also involved in plasticity-dependent synaptogenesis and axon regeneration in the mature brain. Thus, understanding the molecular mechanisms utilized by growth cones is indispensable to understanding neuronal network formation and rearrangement. Phosphorylation is the most important and commonly utilized protein modification in signal transduction. We previously identified microtubule-associated protein 1B (MAP 1B) as the most frequently phosphorylated protein among ~ 1200 phosphorylated proteins. MAP 1B has more than 10 phosphorylation sites that were present more than 50 times among these 1200 proteins. Here, we produced phospho-specific antibodies against phosphorylated serines at positions 25 and 1201 of MAP 1B that specifically recognize growing axons both in cultured neurons and in vivo in various regions of the embryonic brain. Following sciatic nerve injury, immunoreactivity with each antibody increased compared to the sham operated group. Experiments with transected and sutured nerves revealed that regenerating axons were specifically recognized by these antibodies. These results suggest that these MAP 1B phosphorylation sites are specifically involved in axon growth and that phospho-specific antibodies against MAP 1B are useful markers of growing/regenerating axons.

DOI： 10.1186/s13041-019-0510-z

PubMed

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J-GLOBAL

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER IRELAND LTD  

DOI： 10.1016/j.neures.2011.07.254

Web of Science

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER IRELAND LTD  

DOI： 10.1016/j.neures.2009.09.416

Web of Science

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Language：Japanese   Publishing type：Book review, literature introduction, etc.   Publisher：JAPANESE BIOCHEMICAL SOC  

Web of Science

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：BLACKWELL PUBLISHING LTD  

Web of Science

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Language：English   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Symposium, workshop panel (public)  

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Language：English   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Symposium, workshop panel (nominated)  

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Type：Peer review 

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Type：Peer review 

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