Faculty Profiles - OGI Tomoo

Heavy water inhibits DNA double-strand break repairs and disturbs cellular transcription, presumably via quantum-level mechanisms of kinetic isotope effects on hydrolytic enzyme reactions Reviewed Open Access

Yasuda T., Nakajima N., Ogi T., Yanaka T., Tanaka I., Gotoh T., Kagawa W., Sugasawa K., Tajima K.

PLoS ONE Vol. 19 ( 10 October ) 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：PLoS ONE

Heavy water, containing the heavy hydrogen isotope, is toxic to cells, although the underlying mechanism remains incompletely understood. In addition, certain enzymatic proton transfer reactions exhibit kinetic isotope effects attributed to hydrogen isotopes and their temperature dependencies, indicative of quantum tunneling phenomena. However, the correlation between the biological effects of heavy water and the kinetic isotope effects mediated by hydrogen isotopes remains elusive. In this study, we elucidated the kinetic isotope effects arising from hydrogen isotopes of water and their temperature dependencies in vitro, focusing on deacetylation, DNA cleavage, and protein cleavage, which are crucial enzymatic reactions mediated by hydrolysis. Intriguingly, the intracellular isotope effects of heavy water, related to the in vitro kinetic isotope effects, significantly impeded multiple DNA double-strand break repair mechanisms crucial for cell survival. Additionally, heavy water exposure enhanced histone acetylation and associated transcriptional activation in cells, consistent with the in vitro kinetic isotope effects observed in histone deacetylation reactions. Moreover, as observed for the in vitro kinetic isotope effects, the cytotoxic effect on cell proliferation induced by heavy water exhibited temperature-dependency. These findings reveal the substantial impact of heavy water-induced isotope effects on cellular functions governed by hydrolytic enzymatic reactions, potentially mediated by quantum-level mechanisms underlying kinetic isotope effects.

DOI： 10.1371/journal.pone.0309689

Open Access

Treatment-resistant schizophrenia with 22q11.2 deletion and additional genetic defects Reviewed

Furukawa, S; Arafuka, S; Kato, H; Ogi, T; Ozaki, N; Ikeda, M; Kushima, I

NEUROPSYCHOPHARMACOLOGY REPORTS 2024.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Neuropsychopharmacology Reports

We report a case of a 61-year-old female with 22q11.2 deletion syndrome (22q11.2DS) and a novel heterozygous nonsense variant in MAP1A, identified through whole-genome sequencing (WGS). The patient presented with intellectual developmental disorder, treatment-resistant schizophrenia (SCZ), and multiple congenital anomalies. Despite aggressive pharmacotherapy, she experienced persistent auditory hallucinations and negative symptoms. WGS revealed a 3 Mb deletion at 22q11.2 and a nonsense variant in MAP1A (c.4652T>G, p.Leu1551*). MAP1A, encoding microtubule-associated protein 1A, is crucial for axon and dendrite development and has been implicated in autism spectrum disorder and SCZ. The MAP1A variant may contribute to the severe psychiatric phenotype, as it is thought to influence synaptic plasticity, a process also affected by 22q11.2 deletion. This case highlights the importance of WGS in identifying additional pathogenic variants that may explain phenotypic variability in 22q11.2DS. Thus, WGS can lead to a better understanding of the genetic architecture of 22q11.2DS. However, further studies are needed to elucidate the role of secondary genetic contributors in the diverse clinical presentations of 22q11.2DS.

DOI： 10.1002/npr2.12477

The small CRL4CSA ubiquitin ligase component DDA1 regulates transcription-coupled repair dynamics Reviewed

Localized epidermolysis bullosa simplex caused by a previously unreported substitution in the linker 12 domain of keratin 14. Reviewed International journal

Miyu Misaki, Takuya Takeichi, Michiya Omi, Yasutoshi Ito, Tomoo Ogi, Yoshinao Muro, Masashi Akiyama

The Journal of dermatology Vol. 51 ( 8 ) page： e264 - e265 2024.8

Schiffmacher, DAL; Lee, SH; Kliza, KW; Theil, AF; Akita, M; Helfricht, A; Bezstarosti, K; Gonzalo-Hansen, C; van Attikum, H; Verlaan-de Vries, M; Vertegaal, ACO; Hoeijmakers, JHJ; Marteijn, JA; Lans, H; Demmers, JAA; Vermeulen, M; Sixma, TK; Ogi, T; Vermeulen, W; Pines, A

NATURE COMMUNICATIONS Vol. 15 ( 1 ) 2024.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Nature Communications

Transcription-blocking DNA lesions are specifically targeted by transcription-coupled nucleotide excision repair (TC-NER), which removes a broad spectrum of DNA lesions to preserve transcriptional output and thereby cellular homeostasis to counteract aging. TC-NER is initiated by the stalling of RNA polymerase II at DNA lesions, which triggers the assembly of the TC-NER-specific proteins CSA, CSB and UVSSA. CSA, a WD40-repeat containing protein, is the substrate receptor subunit of a cullin-RING ubiquitin ligase complex composed of DDB1, CUL4A/B and RBX1 (CRL4CSA). Although ubiquitination of several TC-NER proteins by CRL4CSA has been reported, it is still unknown how this complex is regulated. To unravel the dynamic molecular interactions and the regulation of this complex, we apply a single-step protein-complex isolation coupled to mass spectrometry analysis and identified DDA1 as a CSA interacting protein. Cryo-EM analysis shows that DDA1 is an integral component of the CRL4CSA complex. Functional analysis reveals that DDA1 coordinates ubiquitination dynamics during TC-NER and is required for efficient turnover and progression of this process.

DOI： 10.1038/s41467-024-50584-7

Two patients with Hailey-Hailey disease with novel pathogenic ATP2C1 variants suggesting possible genotype/phenotype correlations. Reviewed International journal

Michiya Omi, Takuya Takeichi, Yasutoshi Ito, Takenori Yoshikawa, Yuki Mizutani, Miki Nagai, Mariko Seishima, Tomoo Ogi, Yoshinao Muro, Masashi Akiyama

The Journal of dermatology Vol. 51 ( 6 ) page： e185 - e187 2024.6

Dyssegmental dysplasia Rolland-Desbuquois type is caused by pathogenic variants in HSPG2 - a founder haplotype shared in five patients. Reviewed International journal

Paniz Farshadyeganeh, Takahiro Yamada, Hirofumi Ohashi, Gen Nishimura, Hiroki Fujita, Yuriko Oishi, Misa Nunode, Shuku Ishikawa, Jun Murotsuki, Yuri Yamashita, Shiro Ikegawa, Tomoo Ogi, Eri Arikawa-Hirasawa, Kinji Ohno

Journal of human genetics Vol. 69 ( 6 ) page： 235 - 244 2024.6

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

Dyssegmental dysplasia (DD) is a severe skeletal dysplasia comprised of two subtypes: lethal Silverman-Handmaker type (DDSH) and nonlethal Rolland-Desbuquois type (DDRD). DDSH is caused by biallelic pathogenic variants in HSPG2 encoding perlecan, whereas the genetic cause of DDRD remains undetermined. Schwartz-Jampel syndrome (SJS) is also caused by biallelic pathogenic variants in HSPG2 and is an allelic disorder of DDSH. In SJS and DDSH, 44 and 8 pathogenic variants have been reported in HSPG2, respectively. Here, we report that five patients with DDRD carried four pathogenic variants in HSPG2: c.9970 G > A (p.G3324R), c.559 C > T (p.R187X), c7006 + 1 G > A, and c.11562 + 2 T > G. Two patients were homozygous for p.G3324R, and three patients were heterozygous for p.G3324R. Haplotype analysis revealed a founder haplotype spanning 85,973 bp shared in the five patients. SJS, DDRD, and DDSH are allelic disorders with pathogenic variants in HSPG2.

DOI： 10.1038/s10038-024-01229-6

Clearance of DNA damage-arrested RNAPII is selectively impaired in Cockayne syndrome cells Reviewed

Paula J. van der Meer, George Yakoub, Yuka Nakazawa, Tomoo Ogi, Martijn Luijsterburg

2024.5

Natal teeth, hypoplasia of the first toe, and growth retardation in a patient with severe epidermolysis bullosa simplex. Reviewed International journal

Maiko Shimomura-Ishihara, Takuya Takeichi, Tatsuhiro Noda, Haruka Koizumi, Teruyuki Mitsuma, Tomoo Ogi, Yoshinao Muro, Masashi Akiyama

The Journal of dermatology Vol. 51 ( 5 ) page： e175 - e177 2024.5

Endogenous aldehyde-induced DNA-protein crosslinks are resolved by transcription-coupled repair. Reviewed International journal

Yasuyoshi Oka, Yuka Nakazawa, Mayuko Shimada, Tomoo Ogi

Nature cell biology Vol. 26 ( 5 ) page： 784 - 796 2024.5

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

DNA-protein crosslinks (DPCs) induced by aldehydes interfere with replication and transcription. Hereditary deficiencies in DPC repair and aldehyde clearance processes cause progeria, including Ruijs-Aalfs syndrome (RJALS) and AMeD syndrome (AMeDS) in humans. Although the elimination of DPC during replication has been well established, how cells overcome DPC lesions in transcription remains elusive. Here we show that endogenous aldehyde-induced DPC roadblocks are efficiently resolved by transcription-coupled repair (TCR). We develop a high-throughput sequencing technique to measure the genome-wide distribution of DPCs (DPC-seq). Using proteomics and DPC-seq, we demonstrate that the conventional TCR complex as well as VCP/p97 and the proteasome are required for the removal of formaldehyde-induced DPCs. TFIIS-dependent cleavage of RNAPII transcripts protects against transcription obstacles. Finally, a mouse model lacking both aldehyde clearance and TCR confirms endogenous DPC accumulation in actively transcribed regions. Collectively, our data provide evidence that transcription-coupled DPC repair (TC-DPCR) as well as aldehyde clearance are crucial for protecting against metabolic genotoxin, thus explaining the molecular pathogenesis of AMeDS and other disorders associated with defects in TCR, such as Cockayne syndrome.

DOI： 10.1038/s41556-024-01401-2

TERT Promoter Mutations Increase Tumor Aggressiveness by Altering TERT mRNA Splicing in Papillary Thyroid Carcinoma Reviewed

Sako, A; Matsuse, M; Saenko, V; Tanaka, A; Otsubo, R; Morita, M; Kuba, S; Nishihara, E; Suzuki, K; Ogi, T; Kawakami, A; Mitsutake, N

JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM Vol. 109 ( 10 ) page： e1827 - e1838 2024.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Clinical Endocrinology and Metabolism

Context: Telomerase reverse transcriptase promoter (TERT-p) mutations, which upregulate TERT expression, are strongly associated with tumor aggressiveness and worse prognosis in papillary thyroid carcinomas (PTCs). TERT expression is also observed in a proportion of PTCs without TERT-p mutations, but such tumors show less aggressiveness and better prognosis than TERT-p mutation-positive tumors. Objective: TERT has multiple splicing variants whose relationships with the TERT-p status and clinicopathological characteristics remain poorly understood. We examined the relationship between the TERT-p mutational status, the TERT splicing pattern, and clinicopathological features. Methods: We investigated the expression of 2 major variants, α deletion (dA) and β deletion (dB), in a series of 207 PTCs operated on between November 2001 and March 2020 in Nagasaki University Hospital and Kuma Hospital. Results: The TERT-p mutations were found in 33 cases, and among 174 mutation-negative cases, 24 showed TERT expression. All cases were classified into 3 groups: the TERT-p mutation-negative/expression-negative group (mut-/exp-), the TERT-p mutation-negative/expression-positive group (mut-/exp+), and the TERT-p mutation-positive group (mut+/exp+). The +A+B/dB ratio in mut+/exp+ was significantly higher than that in mut-/exp+ PTCs. Analysis with clinicopathological data revealed that +A+B expression was associated with higher PTC aggressiveness, whereas dB expression counteracted this effect. Functional in vitro study demonstrated that dB strongly inhibited cell growth, migration, and clonogenicity, suggesting its tumor-suppressive role. Conclusion: These results provide evidence that the TERT-p mutations alter the expression of different TERT splice variants, which, in turn, associates with different tumor aggressiveness.

DOI： 10.1210/clinem/dgae220

MEFV variants are a predisposing factor for generalized pustular psoriasis Reviewed

Yoshikawa, T; Takeichi, T; Nishida, K; Kobayashi, Y; Sano, H; Shibata, A; Koizumi, H; Tsutsumi, R; Fukaura, R; Hayashi, M; Imanishi, A; Nakamura, K; Mikoshiba, Y; Ogawa, E; Sano, S; Kinoshita, M; Okamoto, T; Kageyama, R; Sano, Y; Kaneko, S; Aoi, J; Hara, T; Togawa, Y; Kishibe, M; Yoshida, Y; Yagi, H; Honda, T; Sugiura, K; Sano, S; Suzuki, T; Ogi, T; Muro, Y; Akiyama, M

JOURNAL OF THE AMERICAN ACADEMY OF DERMATOLOGY Vol. 90 ( 4 ) page： 852 - 854 2024.4

Updated mutational spectrum and genotype-phenotype correlations in ichthyosis patients with ABCA12 pathogenic variants. Reviewed International journal

Tatsuhiro Noda, Takuya Takeichi, Kana Tanahashi, Yasushi Ogawa, So Takeuchi, Takenori Yoshikawa, Erika Toriyama, Miwa Ashida, Sumihisa Imakado, Hitoshi Tsuchihashi, Takashi Okamoto, Yusuke Okuno, Tomoo Ogi, Kazumitsu Sugiura, Akiharu Kubo, Yoshinao Muro, Yasushi Suga, Akemi Ishida-Yamamoto, Masashi Akiyama

Experimental dermatology Vol. 33 ( 4 ) page： e15072 2024.4

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

Autosomal recessive congenital ichthyoses (ARCI) is a genetically heterogeneous condition that can be caused by pathogenic variants in at least 12 genes, including ABCA12. ARCI mainly consists of congenital ichthyosiform erythroderma (CIE), lamellar ichthyosis (LI) and harlequin ichthyosis (HI). The objective was to determine previously unreported pathogenic variants in ABCA12 and to update genotype-phenotype correlations for patients with pathogenic ABCA12 variants. Pathogenic variants in ABCA12 were detected using Sanger sequencing or a combination of Sanger sequencing and whole-exome sequencing. To verify the pathogenicity of a previously unreported large deletion and intron variant, cDNA analysis was performed using total RNA extracted from hair roots. Genetic analyses were performed on the patients with CIE, LI, HI and non-congenital ichthyosis with unusual phenotypes (NIUP), and 11 previously unreported ABCA12 variants were identified. Sequencing of cDNA confirmed the aberrant splicing of the variant ABCA12 in the patients with the previously unreported large deletion and intron variant. Our findings expand the phenotype spectrum of ichthyosis patients with ABCA12 pathogenic variants. The present missense variants in ABCA12 are considered to be heterogenous in pathogenicity, and they lead to varying disease severities in patients with ARCI and non-congenital ichthyosis with unusual phenotypes (NIUP).

DOI： 10.1111/exd.15072

Calcitriol ameliorates motor deficits and prolongs survival of Chrne-deficient mouse, a model for congenital myasthenic syndrome, by inducing Rspo2. Reviewed International journal

Bisei Ohkawara, Hiroyuki Tomita, Taro Inoue, Shaochuan Zhang, Shunsuke Kanbara, Hiroyuki Koshimizu, Yuki Miyasaka, Jun-Ichi Takeda, Hiroshi Nishiwaki, Hiroaki Nakashima, Mikako Ito, Akio Masuda, Naoki Ishiguro, Tomoo Ogi, Tamio Ohno, Shiro Imagama, Kinji Ohno

Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics Vol. 21 ( 2 ) page： e00318 2024.3

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

Signal transduction at the neuromuscular junction (NMJ) is compromised in a diverse array of diseases including congenital myasthenic syndromes (CMS). Germline mutations in CHRNE encoding the acetylcholine receptor (AChR) ε subunit are the most common cause of CMS. An active form of vitamin D, calcitriol, binds to vitamin D receptor (VDR) and regulates gene expressions. We found that calcitriol enhanced MuSK phosphorylation, AChR clustering, and myotube twitching in co-cultured C2C12 myotubes and NSC34 motor neurons. RNA-seq analysis of co-cultured cells showed that calcitriol increased the expressions of Rspo2, Rapsn, and Dusp6. ChIP-seq of VDR revealed that VDR binds to a region approximately 15 kbp upstream to Rspo2. Biallelic deletion of the VDR-binding site of Rspo2 by CRISPR/Cas9 in C2C12 myoblasts/myotubes nullified the calcitriol-mediated induction of Rspo2 expression and MuSK phosphorylation. We generated Chrne knockout (Chrne KO) mouse by CRISPR/Cas9. Intraperitoneal administration of calcitriol markedly increased the number of AChR clusters, as well as the area, the intensity, and the number of synaptophysin-positive synaptic vesicles, in Chrne KO mice. In addition, calcitriol ameliorated motor deficits and prolonged survival of Chrne KO mice. In the skeletal muscle, calcitriol increased the gene expressions of Rspo2, Rapsn, and Dusp6. We propose that calcitriol is a potential therapeutic agent for CMS and other diseases with defective neuromuscular signal transmission.

DOI： 10.1016/j.neurot.2024.e00318

A severe case of cardiospondylocarpofacial syndrome with a novel MAP3K7 variant

Nyuzuki, H; Ozawa, J; Nagasaki, K; Nishio, Y; Ogi, T; Tohyama, J; Ikeuchi, T

HUMAN GENOME VARIATION Vol. 11 ( 1 ) page： 8 2024.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Human Genome Variation

Cardiospondylocarpofacial syndrome (CSCFS) is a congenital malformation characterized by growth retardation, facial features, short toes with carpal and tarsal fusion, extensive posterior neck vertebral fusion, congenital heart disease, and deafness. Here, we report a severe case of CSCFS with a novel variant, p.Thr187Ile, in MAP3K7. Thr187 is the main phosphorylation site for TGF-beta-activated kinase 1 encoded by MAP3K7, and this variant may cause significant abnormalities in downstream signaling.

DOI： 10.1038/s41439-024-00265-0

Genetic background variation impacts microglial heterogeneity and disease progression in amyotrophic lateral sclerosis model mice. Reviewed International journal

Okiru Komine, Syuhei Ohnuma, Kunihiko Hinohara, Yuichiro Hara, Mayuko Shimada, Tomohiro Akashi, Seiji Watanabe, Akira Sobue, Noe Kawade, Tomoo Ogi, Koji Yamanaka

iScience Vol. 27 ( 2 ) page： 108872 - 108872 2024.2

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

Recent single-cell analyses have revealed the complexity of microglial heterogeneity in brain development, aging, and neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). Disease-associated microglia (DAMs) have been identified in ALS mice model, but their role in ALS pathology remains unclear. The effect of genetic background variations on microglial heterogeneity and functions remains unknown. Herein, we established and analyzed two mice models of ALS with distinct genetic backgrounds of C57BL/6 and BALB/c. We observed that the change in genetic background from C57BL/6 to BALB/c affected microglial heterogeneity and ALS pathology and its progression, likely due to the defective induction of neurotrophic factor-secreting DAMs and impaired microglial survival. Single-cell analyses of ALS mice revealed new markers for each microglial subtype and a possible association between microglial heterogeneity and systemic immune environments. Thus, we highlighted the role of microglia in ALS pathology and importance of genetic background variations in modulating microglial functions.

DOI： 10.1016/j.isci.2024.108872

Next-generation sequencing-based detection of Ureaplasma in the gastric fluid of neonates with respiratory distress and chorioamnionitis Reviewed Open Access

Okumura Toshihiko, Horiba Kazuhiro, Tetsuka Nobuyuki, Sato Yoshiaki, Sugiyama Yuichiro, Haruta Kazunori, Yamaguchi Makoto, Suzuki Takako, Torii Yuka, Kawada Jun-ichi, Ogi Tomoo, Hayakawa Masahiro, Ito Yoshinori

JOURNAL OF MATERNAL-FETAL & NEONATAL MEDICINE Vol. 36 ( 1 ) page： 2207113 2023.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Maternal-Fetal and Neonatal Medicine

Background: Respiratory distress is common in neonates admitted to neonatal intensive care units. Additionally, infectious diseases such as intrauterine infections or vertical transmission are important underlying causes of respiratory failure. However, pathogens often cannot be identified in neonates, and there are many cases in which antibacterial drugs are empirically administered. Next-generation sequencing (NGS) is advantageous in that it can detect trace amounts of bacteria that cannot be detected by culturing or bacteria that are difficult to cultivate. However, there are few reports on the diagnosis of infectious diseases using NGS in the neonatal field, especially those targeting respiratory distress. Objective: The purpose of our study was to investigate the microorganisms associated with neonatal respiratory distress and to determine whether less invasive collection specimens such as plasma and gastric fluid are useful. Methods: Neonates were prospectively recruited between January and August 2020 from Nagoya University Hospital. The inclusion criteria were as follows: 1) admission to the neonatal intensive care unit; 2) respiratory distress presentation within 48 h of birth; and 3) suspected infection, collection of blood culture, and administration of antibiotics. Plasma samples and blood cultures were simultaneously collected. Gastric fluid samples were also collected if the patient was not started on enteral nutrition. Information on the patients and their mothers were collected from the medical records. DNA was extracted from 140 µL of plasma and gastric fluid samples. DNA sequencing libraries were prepared, and their quality was analyzed. DNA libraries were sequenced using high-throughput NGS. The NGS data of plasma and gastric fluid samples were analyzed using the metagenomic pipeline PATHDET, which calculated the number of reads assigned to microorganisms and their relative abundance. Putative pathogens were listed. Results: Overall, 30 plasma samples and 25 gastric fluid samples from 30 neonates were analyzed. Microorganism-derived reads of gastric fluid samples were significantly higher than those of plasma samples. Transient tachypnea of the newborn was the most common cause of respiratory distress with 13 cases (43%), followed by respiratory distress syndrome with 7 cases (23%). There were 8 cases (29%) of chorioamnionitis and 7 cases (25%) of funisitis pathologically diagnosed. All blood cultures were negative, and only two gastric fluid cultures were positive for group B Streptococcus (Patient 15) and Candida albicans (Patient 24). Putative pathogens that met the positive criteria for PATHET were detected in four gastric fluid samples, one of which was group B Streptococcus from Patient 15. In the gastric fluid sample of Patient 24, Candida albicans were detected by NGS but did not meet the positive criteria for PATHDET. Cluster analysis of the plasma samples divided them into two study groups, and the indicator genera of each cluster (Phormidium or Toxoplasma) are shown in Figure 1. Clinical findings did not show any significant differences between the two groups. Cluster analysis of the gastric fluid samples divided them into three study groups, and the indicator genera of each cluster (Ureaplasma, Nostoc, and Streptococcus) are shown in Figure 2. The incidence rate of chorioamnionitis was significantly higher in Ureaplasma group than in the other two groups. Conclusion: Gastric fluid may be useful for assessing neonatal patients with respiratory distress. To the best of our knowledge, this was the first study to reveal that the presence of Ureaplasma in the gastric fluid of neonates with respiratory distress was associated with chorioamnionitis. The early diagnosis of intra-amniotic infections using gastric fluid and its treatment may change the treatment strategy for neonatal respiratory distress. Screening for Ureaplasma in neonates with respiratory distress may reduce the need for empirical antibiotic administration. Further research is required to confirm these findings.

DOI： 10.1080/14767058.2023.2207113

Mitochondria-associated membrane collapse impairs TBK1-mediated proteostatic stress response in ALS. Reviewed International journal Open Access

Seiji Watanabe, Yuri Murata, Yasuyoshi Oka, Kotaro Oiwa, Mai Horiuchi, Yohei Iguchi, Okiru Komine, Akira Sobue, Masahisa Katsuno, Tomoo Ogi, Koji Yamanaka

Proceedings of the National Academy of Sciences of the United States of America Vol. 120 ( 47 ) page： e2315347120 2023.11

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

The organelle contact site of the endoplasmic reticulum and mitochondria, known as the mitochondria-associated membrane (MAM), is a multifunctional microdomain in cellular homeostasis. We previously reported that MAM disruption is a common pathological feature in amyotrophic lateral sclerosis (ALS); however, the precise role of MAM in ALS was uncovered. Here, we show that the MAM is essential for TANK-binding kinase 1 (TBK1) activation under proteostatic stress conditions. A MAM-specific E3 ubiquitin ligase, autocrine motility factor receptor, ubiquitinated nascent proteins to activate TBK1 at the MAM, which results in ribosomal protein degradation. MAM or TBK1 deficiency under proteostatic stress conditions resulted in increased cellular vulnerability in vitro and motor impairment in vivo. Thus, MAM disruption exacerbates proteostatic stress via TBK1 inactivation in ALS. Our study has revealed a proteostatic mechanism mediated by the MAM-TBK1 axis, highlighting the physiological importance of the organelle contact sites.

DOI： 10.1073/pnas.2315347120

Lysosomal cholesterol overload in macrophages promotes liver fibrosis in a mouse model of NASH. Reviewed International journal Open Access

Michiko Itoh, Atsushi Tamura, Sayaka Kanai, Miyako Tanaka, Yohei Kanamori, Ibuki Shirakawa, Ayaka Ito, Yasuyoshi Oka, Isao Hidaka, Taro Takami, Yasushi Honda, Mitsuyo Maeda, Yasuyuki Saito, Yoji Murata, Takashi Matozaki, Atsushi Nakajima, Yosky Kataoka, Tomoo Ogi, Yoshihiro Ogawa, Takayoshi Suganami

The Journal of experimental medicine Vol. 220 ( 11 ) 2023.11

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

Accumulation of lipotoxic lipids, such as free cholesterol, induces hepatocyte death and subsequent inflammation and fibrosis in the pathogenesis of nonalcoholic steatohepatitis (NASH). However, the underlying mechanisms remain unclear. We have previously reported that hepatocyte death locally induces phenotypic changes in the macrophages surrounding the corpse and remnant lipids, thereby promoting liver fibrosis in a murine model of NASH. Here, we demonstrated that lysosomal cholesterol overload triggers lysosomal dysfunction and profibrotic activation of macrophages during the development of NASH. β-cyclodextrin polyrotaxane (βCD-PRX), a unique supramolecule, is designed to elicit free cholesterol from lysosomes. Treatment with βCD-PRX ameliorated cholesterol accumulation and profibrotic activation of macrophages surrounding dead hepatocytes with cholesterol crystals, thereby suppressing liver fibrosis in a NASH model, without affecting the hepatic cholesterol levels. In vitro experiments revealed that cholesterol-induced lysosomal stress triggered profibrotic activation in macrophages predisposed to the steatotic microenvironment. This study provides evidence that dysregulated cholesterol metabolism in macrophages would be a novel mechanism of NASH.

DOI： 10.1084/jem.20220681

Open Access