Yuichiro Adachi, M. Allison Williams, Masashi Masuda, Yutaka Taketani, J. Paul Anderson and Pavel Ivanov : Chronic stress antagonizes formation of stress granules, iScience, 29, 1, 114556, 2026.
Yuichiro Adachi, Masashi Masuda, Yutaka Taketani, Paul J. Anderson and Pavel V. Ivanov : Chronic stress disrupts the network among stress granules, P-bodies, and motor proteins., bioRxiv : the preprint server for biology, 2026.
(要約)
Stress granules (SGs) are dynamic RNA granules that rapidly form in response to various stresses concurrent with mRNA translation shutdown, contributing to cellular adaptation and disease pathogenesis. While SG assembly and disassembly under acute stress have been extensively characterized, how SGs behave under chronic stress remains poorly understood. We previously reported that chronic stress preconditioning inhibits the earliest steps of SG assembly via translation-dependent mechanisms. In contrast, the regulation of SG maturation under chronic stress has not yet been investigated. Here, we show that chronic stress decreases SG size by disrupting the MYH9-dependent myosin crosstalk with core SG nucleator G3BP1. This defect leads to impaired SG and processing body (PB) docking as well, limiting the biogenesis of early SGs. Furthermore, chronic stress reduces expression of the SG nucleator UBAP2L, required for SG-PB docking, thus exacerbating these deficiences. In summary, chronic stress disrupts the myosin-SG-PB network and inhibits SG maturation in a translation-independent manner.
Yuichiro Adachi, Allison M. Williams, Masashi Masuda, Yutaka Taketani, Paul J. Anderson and Pavel Ivanov : Chronic stress antagonizes formation of stress granules., iScience, 29, 1, 114556, 2025.
(要約)
Stress granules (SGs) are cytoplasmic ribonucleoprotein condensates formed in response to stress-induced inhibition of mRNA translation and polysome disassembly. Despite the broad interest in SG assembly and disassembly in response to acute stress, SG dynamics under chronic stress has not been extensively investigated. We show that cells pre-conditioned with low-dose chronic (24 h exposure) stresses of various natures fail to assemble SGs in response to acute stress. While protein synthesis is drastically decreased by acute stress in pre-conditioned cells, polysome profiling analysis reveals the partial preservation of polysomes. Mechanistically, chronic stress slows down the rate of mRNA translation at the elongation phase, and triggers phosphorylation of translation elongation factor eEF2. These events further promote ribosome stalling, which is distinct from ribosome collisions known to trigger ribosome-associated quality-control pathways. In summary, chronic stress triggers ribosome stalling, which prevents efficient polysome disassembly and SG formation by subsequent acute stress.
Masaki Takikawa, Hirokazu Ohminami, Takayuki Uchida, Ayano Kitamura, Yuichiro Adachi, Yuki Mori, Kohta Ohnishi, Masashi Masuda, Hisami Yamanaka-Okumura and Yutaka Taketani : Dietary combination of sucrose and linoleic acid increases intramyocellular lipid and impairs muscle strength in female Zucker diabetic fatty rats., Journal of Clinical Biochemistry and Nutrition, 76, 3, 271-279, 2025.
(要約)
Sarcopenic obesity is associated with metabolic disorders and physical limitations. Intramyocellular lipid (IMCL) accumulation is a critical factor affecting muscle strength, independent of muscle mass, in obesity. While diet plays an important role in regulating IMCL, the effects of specific dietary combinations remain poorly understood. This study examined the effects of different combinations of dietary carbohydrates and fats on skeletal muscle quality and function in obese rats. Female Zucker diabetic fatty rats were fed diets containing either sucrose or palatinose combined with either oleic or linoleic acid for 12 weeks. Body and muscle weights, IMCL content, and grip strength were measured. C2C12 myotubes were treated in vitro with varying concentrations of glucose or insulin, along with fatty acids (oleic acid or linoleic acid), to mimic the exposure of each diet. The diet combining sucrose and linoleic acid (SL) significantly increased IMCL accumulation in the extensor digitorum longus (EDL) muscle and reduced grip strength. A negative correlation was observed between IMCL and grip strength. Cluster of differentiation 36 (CD36) protein levels tended to increase in the EDL of the SL diet-fed group. In vitro experiments demonstrated that high glucose levels combined with linoleic acid increased IMCL and CD36 expression. In conclusion, diets high in sucrose and linoleic acid exacerbate IMCL accumulation and reduce muscle strength in obese rats through hyperglycemia-induced interaction.
Anh The Nguyen, Masashi Masuda, Yuki Mori, Yuichiro Adachi, Teppei Fukuda, Airi Furuichi, Masaki Takikawa, Yuki Tsuda, Yuki Hamada, Yusuke Maruyama, Hirokazu Ohminami, Kohta Ohnishi and Yutaka Taketani : All-trans retinoic acid induces lipophagy by reducing Rubicon in Hepa1c1c7 cells., Journal of Lipid Research, 65, 8, 100598, 2024.
(要約)
All-trans retinoic acid (atRA), a metabolite of vitamin A, reduces hepatic lipid accumulation in liver steatosis model animals. Lipophagy, a new lipolysis pathway, degrades a lipid droplet (LD) via autophagy in adipose tissue and the liver. We recently found that atRA induces lipophagy in adipocytes. However, it remains unclear whether atRA induces lipophagy in hepatocytes. In this study, we investigated the effects of atRA on lipophagy in Hepa1c1c7 cells and the liver of mice fed a high-fat diet (HFD). First, we confirmed that atRA induced autophagy in Hepa1c1c7 cells by Western blotting and the GFP-LC3-mCherry probe. Next, we evaluated the lipolysis in fatty Hepa1c1c7 cells treated with the knockdown of Atg5, an essential gene in autophagy induction. Atg5-knockdown partly suppressed the atRA-induced lipolysis in fatty Hepa1c1c7 cells. We also found that atRA reduced the protein, but not mRNA, expression of Rubicon, a negative regulator of autophagy, in Hepa1c1c7 cells and the liver of HFD-fed mice. Rubicon-knockdown partly inhibited the atRA-induced lipolysis in fatty Hepa1c1c7 cells. In addition, atRA reduced hepatic Rubicon expression in young mice, but the effect of atRA on it diminished in aged mice. Finally, we investigated the mechanism underlying reduced Rubicon protein expression by atRA in hepatocytes. A protein synthesis inhibitor, but not proteasome or lysosomal inhibitors, significantly blocked the reduction of Rubicon protein expression by atRA in Hepa1c1c7 cells. These results suggest that atRA may promote lipophagy in fatty hepatocytes by reducing hepatic Rubicon expression via inhibiting protein synthesis.
Yuki Mori, Masashi Masuda, Risa Yoshida-Shimizu, Saki Aoyagi, Yuichiro Adachi, The Anh Nguyen, Yusuke Maruyama, Yosuke Okumura, Yuki Kamei, Maiko Sakai, Kohta Ohnishi, Hirokazu Ohminami and Yutaka Taketani : All-trans retinoic acid induces lipophagy through the activation of the AMPK-Beclin1 signaling pathway and reduces Rubicon expression in adipocytes., The Journal of Nutritional Biochemistry, 126, 2024.
(要約)
Lipophagy is defined as a lipolysis pathway that degrades lipid droplet (LD) via autophagy. All-trans retinoic acid (atRA), a metabolite of vitamin A, stimulates lipolysis through hormone-sensitive lipase and β-oxidation. However, the regulation of lipolysis by atRA-induced autophagy in adipocytes remains unclear. In this study, we investigated the effect of atRA on autophagy in epididymal fat of mice and the molecular mechanisms of autophagy in 3T3-L1 adipocytes. Western blotting showed that atRA decreased the expression of p62, a cargo receptor for autophagic degradation, and increased the expression of the lipidated LC3B (LC3B-II), an autophagy marker, in epididymal fat. Next, we confirmed that atRA increased autophagic flux in differentiated 3T3-L1 cells using the GFP-LC3-RFP-LC3ΔG probe. Immunofluorescent staining revealed that the colocalization of LC3B with perilipin increased in differentiated 3T3-L1 cells treated with atRA. The knockdown of Atg5, an essential gene in autophagy induction, partly suppressed the atRA-induced release of non-esterified fatty acid (NEFA) from LDs in differentiated 3T3-L1 cells. atRA time-dependently elicited the phosphorylation of AMPK and Beclin1, autophagy-inducing factors, in mature 3T3-L1 adipocytes. Inversely, atRA decreased the protein expression of Rubicon, an autophagy repressor, in differentiated 3T3-L1 cells and epididymal fat. Interestingly, the expression of ALDH1A1, atRA-synthesizing enzymes, increased in epididymal fat with decreased protein expression of Rubicon in aged mice. These results suggest that atRA may partially induce lipolysis through lipophagy by activating the AMPK-Beclin1 signaling pathway in the adipocytes and increased atRA levels may contribute to decreased Rubicon expression in the epididymal fat of aged mice. (248/250 words).
Yuki Kamei, Yosuke Okumura, Yuichiro Adachi, Yuki Mori, Maiko Sakai, Kohta Ohnishi, Hirokazu Ohminami, Masashi Masuda, Hisami Yamanaka-Okumura and Yutaka Taketani : Humoral and cellular factors inhibit phosphate-induced vascular calcification during the growth period., Journal of Clinical Biochemistry and Nutrition, 73, 3, 198-204, 2023.
(要約)
, obvious calcification was observed in the adult aorta but not in the young aorta. Furthermore, culture in high Pi medium increased the mRNA level of tissue-nonspecific alkaline phosphatase (TNAP), which degrades pyrophosphate, only in the adult aorta. Collectively, our findings indicate that the aorta in growing mouse may be resistant to Pi-induced vascular calcification via a mechanism in which high serum fetuin-A levels and suppressed TNAP expression.
Masashi Masuda, Risa Yoshida-Shimizu, Yuki Mori, Kohta Ohnishi, Yuichiro Adachi, Maiko Sakai, Serina Kabutoya, Hirokazu Ohminami, Hirokazu Ohminami, Hironori Yamamoto, Makoto Miyazaki and Yutaka Taketani : Sulforaphane induces lipophagy through the activation of AMPK-mTOR-ULK1 pathway signaling in adipocytes., The Journal of Nutritional Biochemistry, 106, 109017, 2022.
(要約)
Lipophagy, a form of selective autophagy, degrades lipid droplet (LD) in adipose tissue and the liver. The chemotherapeutic isothiocyanate sulforaphane (SFN) contributes to lipolysis through the activation of hormone-sensitive lipase and the browning of white adipocytes. However, the details concerning the regulation of lipolysis in adipocytes by SFN-mediated autophagy remain unclear. In this study, we investigated the effects of SFN on autophagy in the epididymal fat of mice fed a high-fat diet (HFD) or control-fat diet and on the molecular mechanisms of autophagy in differentiated 3T3-L1 cells. Western blotting revealed that the protein expression of lipidated LC3 (LC3-II), an autophagic substrate, was induced after 3T3-L1 adipocytes treatment with SFN. In addition, SFN increased the LC3-II protein expression in the epididymal fat of mice fed an HFD. Immunofluorescence showed that the SFN-induced LC3 expression was co-localized with LDs in 3T3-L1 adipocytes and with perilipin, the most abundant adipocyte-specific protein, in adipocytes of mice fed an HFD. Next, we confirmed that SFN activates autophagy flux in differentiated 3T3-L1 cells using the mCherry-EGFP-LC3 and GFP-LC3-RFP-LC3 probe. Furthermore, we examined the induction mechanisms of autophagy by SFN in 3T3-L1 adipocytes using western blotting. ATG5 knockdown partially blocked the SFN-induced release of fatty acids from LDs in mature 3T3-L1 adipocytes. SFN time-dependently elicited the phosphorylation of AMPK, the dephosphorylation of mTOR, and the phosphorylation of ULK1 in differentiated 3T3-L1 cells. Taken together, these results suggest that SFN may provoke lipophagy through AMPK-mTOR-ULK1 pathway signaling, resulting in partial lipolysis of adipocytes.
Yuichiro Adachi, Masashi Masuda, Iori Sakakibara, Takayuki Uchida, Yuki Niida, Yuki Mori, Yuki Kamei, Yosuke Okumura, Hirokazu Ohminami, Kohta Ohnishi, Hisami Okumura, Takeshi Nikawa and Yutaka Taketani : All-trans retinoic acid changes muscle fiber type via increasing GADD34 dependent on MAPK signal., Life Science Alliance, 5, 7, 2022.
(要約)
All-trans retinoic acid (ATRA) increases the sensitivity to unfolded protein response in differentiating leukemic blasts. The downstream transcriptional factor of PERK, a major arm of unfolded protein response, regulates muscle differentiation. However, the role of growth arrest and DNA damage-inducible protein 34 (GADD34), one of the downstream factors of PERK, and the effects of ATRA on GADD34 expression in muscle remain unclear. In this study, we identified ATRA increased the GADD34 expression independent of the PERK signal in the gastrocnemius muscle of mice. ATRA up-regulated GADD34 expression through the transcriptional activation of gene via inhibiting the interaction of homeobox Six1 and transcription co-repressor TLE3 with the MEF3-binding site on the gene promoter in skeletal muscle. ATRA also inhibited the interaction of TTP, which induces mRNA degradation, with AU-rich element on mRNA via p-38 MAPK, resulting in the instability of mRNA. Overexpressed GADD34 in C2C12 cells changes the type of myosin heavy chain in myotubes. These results suggest ATRA increases GADD34 expression via transcriptional and post-transcriptional regulation, which changes muscle fiber type.
Masashi Masuda, Hironori Yamamoto, Yuichiro Takei, Otoki Nakahashi, Yuichiro Adachi, Kohta Ohnishi, Hirokazu Ohminami, Hisami Yamanaka-Okumura, Hiroshi Sakaue, Makoto Miyazaki, Eiji Takeda and Yutaka Taketani : All-trans retinoic acid reduces the transcriptional regulation of intestinal sodium-dependent phosphate co-transporter gene (Npt2b)., The Biochemical Journal, 477, 4, 817-831, 2020.
(要約)
Inorganic phosphate (Pi) homeostasis is regulated by intestinal absorption via type II sodium-dependent co-transporter (Npt2b) and by renal reabsorption via Npt2a and Npt2c. Although we previously reported that vitamin A-deficient (VAD) rats had increased urine Pi excretion through the decreased renal expression of Npt2a and Npt2c, the effect of vitamin A on the intestinal Npt2b expression remains unclear. In this study, we investigated the effects of treatment with all-trans retinoic acid (ATRA), a metabolite of vitamin A, on the Pi absorption and the Npt2b expression in the intestine of VAD rats, as well as and the underlying molecular mechanisms. In VAD rats, the intestinal Pi uptake activity and the expression of Npt2b were increased, but were reduced by the administration of ATRA. The transcriptional activity of reporter plasmid containing the promoter region of the rat Npt2b gene was reduced by ATRA in NIH3T3 cells overexpressing retinoic acid receptor (RAR) and retinoid X receptor (RXR). On the other hand, CCAAT/enhancer-binding proteins (C/EBP) induced transcriptional activity of the Npt2b gene. Knockdown of the C/EBP gene and a mutation analysis of the C/EBP responsible element in the Npt2b gene promoter indicated that C/EBP plays a pivotal role in the regulation of Npt2b gene transcriptional activity by ATRA. EMSA revealed that the RAR/RXR complex inhibits binding of C/EBP to Npt2b gene promoter. Together, these results suggest that ATRA may reduce the intestinal Pi uptake by preventing C/EBP activation of the intestinal Npt2b gene.
Yuki Niida, Masashi Masuda, Yuichiro Adachi, Aika Yoshizawa, Hirokazu Ohminami, Yuki Mori, Kohta Ohnishi, Hisami Okumura, Takayuki Uchida, Takeshi Nikawa, Hironori Yamamoto, Makoto Miyazaki and Yutaka Taketani : Reduction of stearoyl-CoA desaturase (SCD) contributes muscle atrophy through the excess endoplasmic reticulum stress in chronic kidney disease, Journal of Clinical Biochemistry and Nutrition, 67, 2, 179-187, 2020.
(要約)
<p>Skeletal muscle atrophy is associated with mortality and poor prognosis in patients with chronic kidney disease (CKD). However, underlying mechanism by which CKD causes muscle atrophy has not been completely understood. The quality of lipids (lipoquality), which is defined as the functional features of diverse lipid species, has recently been recognized as the pathology of various diseases. In this study, we investigated the roles of the stearoyl-CoA desaturase (SCD), which catalyzes the conversion of saturated fatty acids into monounsaturated fatty acids, in skeletal muscle on muscle atrophy in CKD model animals. In comparison to control rats, CKD rats decreased the SCD activity and its gene expression in atrophic gastrocnemius muscle. Next, oleic acid blocked the reduction of the thickness of C2C12 myotubes and the increase of the endoplasmic reticulum stress induced by SCD inhibitor. Furthermore, endoplasmic reticulum stress inhibitor ameliorated CKD-induced muscle atrophy (the weakness of grip strength and the decrease of muscle fiber size of gastrocnemius muscle) in mice and the reduction of the thickness of C2C12 myotubes by SCD inhibitor. These results suggest that the repression of SCD activity causes muscle atrophy through excessive endoplasmic reticulum stress in CKD.</p>
Yuichiro Adachi, Williams M Allison, Masashi Masuda, Yutaka Taketani, Anderson J Paul and Ivanov Pavel : Stress granules at the crossroad of acute and chronic stress, RNA granule meeting, Oct. 2023.
2.
Yuichiro Adachi, Masashi Masuda, Kohei Sasaki, Hirokazu Ohminami, Hisami Okumura, Hironori Yamamoto and Yutaka Taketani : Hypervitaminosis A Contributes to Kidney Injury Through Excessive Endoplasmic Reticulum Stress in CKD, ASN Kidney Week 2021, Nov. 2021.
3.
Masashi Masuda, Hironori Yamamoto, Yuichiro Adachi, Kohta Ohnishi, Hirokazu Ohminami, Hisami Okumura, Makoto Miyazaki, Eiji Takeda and Yutaka Taketani : All-trans-retinoic-acid reduces intestinal phosphate uptake by the transcriptional regulation of sodium-dependent phosphate co-transporter gene (Npt2b)., ASBMR 2019 Annual Meeting, Sep. 2019.
4.
Serina Kabutoya, Masashi Masuda, Yuichiro Adachi, Yilimulati Timamu, Hisami Okumura, Hironori Yamamoto and Yutaka Taketani : Hypervitaminosis A contributes to abnormal iron metabolism in CKD, American Society of Nephrology Kidney Week 2018, San Diego, Oct. 2018.