Publications

Mitophagy degrades damaged mitochondria, but we show here that it can also target functional mitochondria. This latter scenario occurs during programmed mitophagy and involves the mitophagy receptors NIX and BNIP3. Although AMP-activated protein kinase (AMPK), the energy-sensing protein kinase, can influence damaged-induced mitophagy, its role in programmed mitophagy is unclear. We found that AMPK directly inhibits NIX-dependent mitophagy by triggering 14-3-3-mediated sequestration of ULK1, via ULK1 phosphorylation at two sites: Ser556 and an additional identified site, Ser694. By contrast, AMPK activation increases Parkin phosphorylation and enhances the rate of depolarization-induced mitophagy, independently of ULK1. We show that this happens both in cultured cells and tissues in vivo, using the mito-QC mouse model. Our work unveils a mechanism whereby AMPK activation downregulates mitophagy of functional mitochondria but enhances that of dysfunctional/damaged ones.

We outline a protocol to visualize all mouse lower hindlimb skeletal muscles simultaneously. We describe procedures for orientating the whole lower hindlimb in gum tragacanth prior to freezing, simplifying the proceeding experimental steps, and enhancing the comprehensiveness of characterizations. We then detail steps for quantifying muscle fiber size and fiber type characteristics in a single cryosection using histochemistry and immunofluorescence. This protocol can be applied to histological and (immuno)histochemical evaluations such as muscle regeneration, fibrosis, enzymatic activity, and glycogen content.

BACKGROUND: Preoperative chemotherapy with 5-fluorouracil and cisplatin (FP) followed by surgery has been considered a standard treatment for patients with stage II/III esophageal squamous cell carcinoma (ESCC) based on the results of a phase III trial (JCOG9907) in Japan. Subsequently, the phase III NExT trial (JCOG1109) revealed the survival benefit of the neoadjuvant DCF regimen, which adds docetaxel to FP, and it became a standard treatment. However, the long-term results and prognostic factors of neoadjuvant DCF therapy in the real world are unknown.

METHODS: We retrospectively investigated 50 patients with ESCC treated with neoadjuvant DCF therapy from July 2012 to December 2017 at The University of Tokyo Hospital.

RESULTS: Median overall survival (OS) and progression-free survival (PFS) were 32.3 [95% confidence interval (CI) 21.0-NA] and 10.0 months (95% CI 6.3-15.6), respectively. Median OS [not reached (95% CI 31.5-NA) vs. 21.4 months (95% CI 13.5-33.0); p = 0.028] and PFS [83.3 months (95% CI 6.4-NA) vs. 7.4 months (95% CI 6.0-12.8] were significantly longer in patients with an objective response than in non-responders. Of 44 surgical cases, median PFS tended to be longer in pathological lymph node metastasis-negative patients. Conversely, survival did not differ according to cStage (II/III vs. IV) or the average relative dose intensity (ARDI, ≥ 85% vs. < 85%).

DISCUSSION: The response to neoadjuvant DCF therapy could predict patient prognosis. Additionally, pN+ tended to increase the recurrence risk, whereas cStage and ARDI did not influence survival.

Several surgical techniques have been documented for approaching and repairing superior semicircular canal dehiscence syndrome (SCDS). These techniques encompass the trans-middle cranial fossa, transmastoid, endoscopic approaches, and round window reinforcement (RWR). RWR entails the placement of connective tissue with or without cartilage and around the round window niche, restricting the round window's movement to minimize the 3rd window effect and restore the bony labyrinth closer to its normal state. We employed the multilayer RWR technique, resulting in significant postoperative improvement and long-lasting effects for 3.7 years in 2 cases. Here, we present the clinical findings, surgical procedures, and the effectiveness of multilayer RWR. This technique can be the initial choice for surgical treatments of SCDS due to its high effectiveness, longer-lasting effect, and minimal risk of surgical complications.

The cellular mechanisms underlying axonal morphogenesis are essential to the formation of functional neuronal networks. We previously identified the autism-linked kinase NUAK1 as a central regulator of axon branching through the control of mitochondria trafficking. However, (1) the relationship between mitochondrial position, function and axon branching and (2) the downstream effectors whereby NUAK1 regulates axon branching remain unknown. Here, we report that mitochondria recruitment to synaptic boutons supports collateral branches stabilization rather than formation in mouse cortical neurons. NUAK1 deficiency significantly impairs mitochondrial metabolism and axonal ATP concentration, and upregulation of mitochondrial function is sufficient to rescue axonal branching in NUAK1 null neurons in vitro and in vivo. Finally, we found that NUAK1 regulates axon branching through the mitochondria-targeted microprotein BRAWNIN. Our results demonstrate that NUAK1 exerts a dual function during axon branching through its ability to control mitochondrial distribution and metabolic activity.

Phosphine periodic mesoporous organosilicas (R-P-PMO-TMS: R=Ph, tBu), which possess electron-donating alkyl substituents on the phosphorus atom, were synthesized using bifunctional compounds with alkoxysilyl- and phosphino groups, bis[3-(triethoxysilyl)propyl]phenylphosphine borane (1 a) and bis[3-(triethoxysilyl)propyl]-tert-butylphosphine borane (1 b). Immobilization of Pd(0) species was performed to give R-P-Pd-PMO-TMS: R=Ph (2 a), tBu (3 a), respectively. The Pd(0) immobilized 2 a and 3 a were applicable as catalysts for Suzuki-Miyaura cross-coupling reactions of aryl chlorides with phenylboronic acid. It was revealed that 3 a bearing more electron-donating tBu groups exhibited higher catalytic activity. Various functional groups including both electron withdrawing and donating substituents were compatible in the system. The recyclability of 3 a was examined to support its moderate utility for the recycle use.

These days, easy access to commercially available (poly)phenolic compounds has expanded the scope of potential research beyond the field of chemistry, particularly in the area of their bioactivity. However, the quality of these compounds is often overlooked or not even considered. This issue is illustrated in this study through the example of (dihydro)phenanthrenes, a group of natural products present in yams, as AMP-activated protein kinase (AMPK) activators. A study conducted in our group on a series of compounds, fully characterized using a combination of chemical synthesis, NMR and MS techniques, provided evidence that the conclusions of a previous study were erroneous, likely due to the use of a misidentified commercial compound by its supplier. Furthermore, we demonstrated that additional representatives of the (dihydro)phenanthrene phytochemical classes were able to directly activate AMPK, avoiding the risk of misinterpretation of results based on analysis of a single compound alone.

BACKGROUND: Preoperative chemotherapy with 5-fluorouracil and cisplatin (FP) followed by surgery has been considered a standard treatment for patients with stage II/III esophageal squamous cell carcinoma (ESCC) based on the results of a phase III trial (JCOG9907) in Japan. Subsequently, the phase III NExT trial (JCOG1109) revealed the survival benefit of the neoadjuvant DCF regimen, which adds docetaxel to FP, and it became a standard treatment. However, the long-term results and prognostic factors of neoadjuvant DCF therapy in the real world are unknown.

METHODS: We retrospectively investigated 50 patients with ESCC treated with neoadjuvant DCF therapy from July 2012 to December 2017 at The University of Tokyo Hospital.

RESULTS: Median overall survival (OS) and progression-free survival (PFS) were 32.3 [95% confidence interval (CI) 21.0-NA] and 10.0 months (95% CI 6.3-15.6), respectively. Median OS [not reached (95% CI 31.5-NA) vs. 21.4 months (95% CI 13.5-33.0); p = 0.028] and PFS [83.3 months (95% CI 6.4-NA) vs. 7.4 months (95% CI 6.0-12.8] were significantly longer in patients with an objective response than in non-responders. Of 44 surgical cases, median PFS tended to be longer in pathological lymph node metastasis-negative patients. Conversely, survival did not differ according to cStage (II/III vs. IV) or the average relative dose intensity (ARDI, ≥ 85% vs. < 85%).

DISCUSSION: The response to neoadjuvant DCF therapy could predict patient prognosis. Additionally, pN+ tended to increase the recurrence risk, whereas cStage and ARDI did not influence survival.

Reversible phosphorylation of the transcription factor EB (TFEB) coordinates cellular responses to metabolic and other stresses. During nutrient replete and stressor-free conditions, phosphorylated TFEB is primarily localized to the cytoplasm. Stressor-mediated reduction of TFEB phosphorylation promotes its nuclear translocation and context-dependent transcriptional activity. In this study, we explored targeted dephosphorylation of TFEB as an approach to activate TFEB in the absence of nutrient deprivation or other cellular stress. Through an induction of proximity between TFEB and several phosphatases using the AdPhosphatase system, we demonstrate targeted dephosphorylation of TFEB in cells. Furthermore, by developing a heterobifunctional molecule BDPIC (bromoTAG-dTAG proximity-inducing chimera), we demonstrate targeted dephosphorylation of TFEB-dTAG through induced proximity to bromoTAG-PPP2CA. Targeted dephosphorylation of TFEB-dTAG by bromoTAG-PPP2CA with BDPIC at the endogenous levels is sufficient to induce nuclear translocation and some transcriptional activity of TFEB.

River discharge to the ocean influences the transport of salts and nutrients and is a source of variability in water mass distribution and the elemental cycle. Recently, using an underwater glider, we detected thick, low-salinity water offshore for the first time, probably derived from coastal waters, in the central-eastern Sea of Japan, whose primary productivity is comparable to that of the western North Pacific. Thereafter, we aimed to investigate the offshore advection and diffusion of coastal water and its variability and assess their impact. We examined the effects of river water discharge on the flow field and biological production. Numerical experiments demonstrated that low-salinity water observed by the glider in spring was discharged from the Japanese coast to offshore regions. The water is discharged offshore because of its interaction with mesoscale eddies. A relationship between the modeled low-salinity water transport to the offshore region and the observed chlorophyll-a in the offshore region was also observed, indicating the influence of river water on offshore biological production. This study contributes to understanding coastal-offshore water exchange, ocean circulation, elemental cycles, and biological production, which are frontiers in the Sea of Japan and throughout the world.