Aurora A and AKT Kinase Signaling Associated with Primary Cilia

Dysregulation of kinase signaling is associated with various pathological conditions, including cancer, inflammation, and autoimmunity; consequently, the kinases involved have become major therapeutic targets. While kinase signaling pathways play crucial roles in multiple cellular processes, the precise manner in which their dysregulation contributes to disease is dependent on the context; for example, the cell/tissue type or subcellular localization of the kinase or substrate. Thus, context-selective targeting of dysregulated kinases may serve to increase the therapeutic specificity while reducing off-target adverse effects. Primary cilia are antenna-like structures that extend from the plasma membrane and function by detecting extracellular cues and transducing signals into the cell. Cilia formation and signaling are dynamically regulated through context-dependent mechanisms; as such, dysregulation of primary cilia contributes to disease in a variety of ways. Here, we review the involvement of primary cilia-associated signaling through aurora A and AKT kinases with respect to cancer, obesity, and other ciliopathies

新規デスミンリン酸化不全遺伝子改変マウスにおける筋組織形成・機能の解析

application/pdf筋組織特異的な中間径フィラメントであるデスミンのリン酸化の生理的意義を明らかにするため、デスミンリン酸化不全マウスを作製した。デスミンリン酸化不全マウスは野生型マウスと比べ、外観の差は認められなかった。一方で、心筋のデスミン発現が経時的に減少することが分かり、心機能の評価が今後の課題となった。また、骨格筋に関しては、グリセロール投与による急性骨格筋障害を誘導すると、デスミンリン酸化不全マウスは野生型マウスに比べ、障害範囲が広く、筋再生の遅延がみられた。今後、既存筋組織の恒常性について、そして筋肉幹細胞である筋衛星細胞からの分化異常について詳細な機能解析が必要である。To understand the physiological significance of mitotic phosphorylation of muscle specific intermediate filament desmin, we generated mitotic desmin phosphorylation defective mice (DES SA/SA mice). Compare to wild type mice, DES SA/SA mice were no difference of appearance. However, in heart muscle tissue, DES SA/SA mice showed decrease of desmin expression in Z band area except intercalated disc. Therefore, we need to clarify heart function in the future. In skeletal muscle tissue, when we induced muscle injury by glycerol injention, DES SA/SA mice were injured broadly and delayed muscle regeneration. In future, we will work on solution of detail mechanism with regards to pre-existing muscle tissue homeostasis and abnormal cell division of muscle stem cell which is called satellite cell.2017年度～2019年度科学研究費補助金(若手研究(B))研究成果報告書17K1561

Targeting E3 Ubiquitin Ligases and Deubiquitinases in Ciliopathy and Cancer

Cilia are antenna-like structures present in many vertebrate cells. These organelles detect extracellular cues, transduce signals into the cell, and play an essential role in ensuring correct cell proliferation, migration, and differentiation in a spatiotemporal manner. Not surprisingly, dysregulation of cilia can cause various diseases, including cancer and ciliopathies, which are complex disorders caused by mutations in genes regulating ciliary function. The structure and function of cilia are dynamically regulated through various mechanisms, among which E3 ubiquitin ligases and deubiquitinases play crucial roles. These enzymes regulate the degradation and stabilization of ciliary proteins through the ubiquitin–proteasome system. In this review, we briefly highlight the role of cilia in ciliopathy and cancer; describe the roles of E3 ubiquitin ligases and deubiquitinases in ciliogenesis, ciliopathy, and cancer; and highlight some of the E3 ubiquitin ligases and deubiquitinases that are potential therapeutic targets for these disorders

An angiogenic role for adrenomedullin in choroidal neovascularization.

PURPOSE: Adrenomedullin (ADM) has been shown to take part in physiological and pathological angiogenesis. The purpose of this study was to investigate whether ADM signaling is involved in choroidal neovascularization (CNV) using a mouse model. METHODS AND RESULTS: CNV was induced by laser photocoagulation in 8-week-old C57BL/6 mice. ADM mRNA expression significantly increased following treatment, peaking 4 days thereafter. The expression of ADM receptor (ADM-R) components (CRLR, RAMP2 and RAMP 3) was higher in CD31(+)CD45(-) endothelial cells (ECs) than CD31(-)CD45(-) non-ECs. Inflammatory stimulation upregulated the expression of ADM not only in cell lines but also in cells in primary cultures of the choroid/retinal pigment epithelium complex. Supernatants from TNFα-treated macrophage cell lines potentiated the proliferation of ECs and this was partially suppressed by an ADM antagonist, ADM (22-52). Intravitreous injection of ADM (22-52) or ADM neutralizing monoclonal antibody (mAb) after laser treatment significantly reduced the size of CNV compared with vehicle-treated controls (p<0.01). CONCLUSIONS: ADM signaling is involved in laser-induced CNV formation, because both an ADM antagonist and ADM mAb significantly inhibited it. Suppression of ADM signaling might be a valuable alternative treatment for CNV associated with age-related macular degeneration

Ligand-independent Tie2 dimers mediate kinase activity stimulated by high dose angiopoietin-1

金沢大学医薬保健研究域医学系Tie2 is a receptor tyrosine kinase expressed on vascular endothelial cells (ECs). It has dual roles in promoting angiogenesis and stabilizing blood vessels, and it has been suggested that Tie2 forms dimers and/or oligomers in the absence of angiopoietin-1 (Ang1); however, the mechanism of ligand-independent dimerization of Tie2 and its biological significance have not been clarified. Using a bimolecular fluorescence complementation assay and a kinase-inactive Tie2 mutant, we show here that ligand-independent Tie2 dimerization is induced without Tie2 phosphorylation. Moreover, based on the fact that Tie1 never forms heterodimers with Tie2 in the absence of Ang1 despite having high amino acid sequence homology with Tie2, we searched for ligand-independent dimerization domains of Tie2 by reference to the difference with Tie1. We found that the YIA sequence of the intracellular domain of Tie2 corresponding to the LAS sequence in Tie1 is essential for this dimerization. When the YIA sequence was replaced by LAS in Tie2 (Tie2YIA/LAS), ligand-independent dimer was not formed in the absence of Ang1. When activation of Tie2YIA/LAS was induced by a high dose of Ang1, phosphorylation of Tie2 was limited compared with wild-type Tie2, resulting in retardation of activation of Erk downstream of Tie2. Therefore, these data suggest that ligand-independent dimerization of Tie2 is essential for a strong response upon stimulation with high dose Ang1. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc

An Angiogenic Role for Adrenomedullin in Choroidal Neovascularization

金沢大学医薬保健研究域医学系Purpose: Adrenomedullin (ADM) has been shown to take part in physiological and pathological angiogenesis. The purpose of this study was to investigate whether ADM signaling is involved in choroidal neovascularization (CNV) using a mouse model. Methods and Results: CNV was induced by laser photocoagulation in 8-week-old C57BL/6 mice. ADM mRNA expression significantly increased following treatment, peaking 4 days thereafter. The expression of ADM receptor (ADM-R) components (CRLR, RAMP2 and RAMP 3) was higher in CD31+CD45- endothelial cells (ECs) than CD31-CD45- non-ECs. Inflammatory stimulation upregulated the expression of ADM not only in cell lines but also in cells in primary cultures of the choroid/retinal pigment epithelium complex. Supernatants from TNFα-treated macrophage cell lines potentiated the proliferation of ECs and this was partially suppressed by an ADM antagonist, ADM (22-52). Intravitreous injection of ADM (22-52) or ADM neutralizing monoclonal antibody (mAb) after laser treatment significantly reduced the size of CNV compared with vehicle-treated controls (p&lt;0.01). Conclusions: ADM signaling is involved in laser-induced CNV formation, because both an ADM antagonist and ADM mAb significantly inhibited it. Suppression of ADM signaling might be a valuable alternative treatment for CNV associated with age-related macular degeneration. © 2013 Sakimoto et al