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The macronutrients glucose, lipids, and amino acids are the major components that maintain life. The ability of cells to sense and respond to fluctuations in these nutrients is a crucial feature for survival. Nutrient-sensing pathways are thus developed to govern cellular energy and metabolic homeostasis and regulate diverse biological processes. Accordingly, perturbations in these sensing pathways are associated with a wide variety of pathologies, especially metabolic diseases. Molecular sensors are the core within these sensing pathways and have a certain degree of specificity and affinity to sense the intracellular fluctuation of each nutrient either by directly binding to that nutrient or indirectly binding to its surrogate molecules. Once the changes in nutrient levels are detected, sensors trigger signaling cascades to fine-tune cellular processes for energy and metabolic homeostasis, for example, by controlling uptake, de novo synthesis or catabolism of that nutrient. In this review, we summarize the major discoveries on nutrient-sensing pathways and explain how those sensors associated with each pathway respond to intracellular nutrient availability and how these mechanisms control metabolic processes. Later, we further discuss the crosstalk between these sensing pathways for each nutrient, which are intertwined to regulate overall intracellular nutrient/metabolic homeostasis. Metabolism: nutrient sensors and their networks The ability of cells to sense levels of important nutrients, such as glucose, lipids, and amino acids, is critical for cellular health, and dysregulation such sensing activity can underlie various diseases, especially metabolic diseases. Sensing nutrient levels allows cells to regulate their metabolism and to maintain appropriate nutrient levels by taking up, synthesizing, or breaking down a given nutrient. Jung Min Han at Yonsei University in South Korea and co-workers have reviewed recent discoveries on nutrient sensors and the networks connecting them. Although researchers have identified the sensors of some key molecules, such as glucose and important amino acids such as leucine, how sensing networks interact is poorly understood. Improving our understanding of nutrient sensing will illuminate nutrient supply in both health and disease, and may help to find treatments for metabolic disorders.

Human bocavirus (HBoV) has been identified as a viral agent with a global presence, especially in young patients with gastrointestinal infections. In this study, we aimed to evaluate the epidemiological patterns of the HBoVs associated with acute gastroenteritis (AGE) in Taiwan. A total of 2994 AGE fecal samples from several diarrhea outbreaks from 2018 to 2022 were analyzed. From the samples, 73 positive samples were detected in three different bocaviruses: 30 (41.1%) were from HBoV1; 37 (50.7%) were from HBoV2; and 6 (8.2%) were from HBoV3, revealing the respective prevalences in AGE of 1%, 1.2%, and 0.2%. HBoV1 and HBoV2 were the two major epidemic agents of HBoVs in Taiwan during this study period and have seasonal distinct patterns with an epidemic peak from October to the following March. Phylogeny reconstruction and evaluation were implemented in Mega X; the results revealed that most HBoV1 strains in Taiwan appeared to be closely related to those strains from other Asian countries. The HBoV2 exhibited substantial genetic diversity and the HBoV3 genes showed discordance of groups.

As knowledge of cell metabolism has advanced, glutamine has been considered an important amino acid that supplies carbon and nitrogen to fuel biosynthesis. A recent study provided a new perspective on mitochondrial glutamine metabolism, offering mechanistic insights into metabolic adaptation during tumor hypoxia, the emergence of drug resistance, and glutaminolysis-induced metabolic reprogramming and presenting metabolic strategies to target glutamine metabolism in cancer cells. In this review, we introduce the various biosynthetic and bioenergetic roles of glutamine based on the compartmentalization of glutamine metabolism to explain why cells exhibit metabolic reliance on glutamine. Additionally, we examined whether glutamine derivatives contribute to epigenetic regulation associated with tumorigenesis. In addition, in discussing glutamine transporters, we propose a metabolic target for therapeutic intervention in cancer.Amino acid metabolism: Glutamine in healthy and cancerous cellsInsights into how the amino acid glutamine powers cellular metabolism could pave the way for effective therapeutic strategies for ‘starving’ tumor cells. Healthy cells can manufacture enough glutamine to sustain normal function, but cancerous growth creates heavier demand for this important molecule. Jung Min Han and colleagues at Yonsei University in Incheon, South Korea have reviewed the various cellular functions of glutamine, and discuss opportunities to cut off supply and thereby derail tumor proliferation. Glutamine serves as a building block both for amino acids and nucleic acids, and is also consumed during mitochondrial energy production. Several groups are exploring the feasibility of inactivating glutamine synthesis or halting cellular uptake of this amino acid as a means of depriving cancer cells of nutrients. A deeper understanding of glutamine’s metabolic functions should accelerate progress on this front.

All living organisms have the ability to sense nutrient levels to coordinate cellular metabolism. Despite the importance of nutrient-sensing pathways that detect the levels of amino acids and glucose, how the availability of these two types of nutrients is integrated is unclear. Here, we show that glucose availability regulates the central nutrient effector mTORC1 through intracellular leucine sensor leucyl-tRNA synthetase 1 (LARS1). Glucose starvation results in O -GlcNAcylation of LARS1 on residue S1042. This modification inhibits the interaction of LARS1 with RagD GTPase and reduces the affinity of LARS1 for leucine by promoting phosphorylation of its leucine-binding site by the autophagy-activating kinase ULK1, decreasing mTORC1 activity. The lack of LARS1 O -GlcNAcylation constitutively activates mTORC1, supporting its ability to sense leucine, and deregulates protein synthesis and leucine catabolism under glucose starvation. This work demonstrates that LARS1 integrates leucine and glucose availability to regulate mTORC1 and the metabolic fate of leucine. Leucyl-tRNA synthetase 1 (LARS1) is a leucine sensor for mTORC1 signaling and regulates leucine utilization depending on glucose availability. Here, the author show that O -GlcNAcylation of LARS1 is crucial for its ability to regulate mTORC1 activity and leucine metabolism upon glucose starvation.

The mitochondrial glutamine transporter SLC1A5_var plays a central role in the metabolic reprogramming of cancer cells by facilitating glutamine import into mitochondria for energy production and redox homeostasis. Despite its critical function, the development of effective and selective inhibitors targeting SLC1A5_var has remained a significant challenge. Here, we introduce iMQT_020, a selective allosteric inhibitor identified through structure-based screening. iMQT_020 disrupts the trimeric assembly of SLC1A5_var, causing metabolic crisis in cancer cells and selectively suppressing their growth. Mechanistically, iMQT_020 reduces glutamine anaplerosis and oxidative phosphorylation, resulting in a broad disruption of cancer metabolism. Additionally, iMQT_020 treatment epigenetically upregulates PD-L1 expression, enhancing the efficacy of combination therapies with anti-PD-L1 immune checkpoint inhibitors. These findings highlight the therapeutic potential of targeting SLC1A5_var as a critical metabolic vulnerability in cancer and demonstrate that targeting allosteric interprotomer interactions is a novel and promising therapeutic strategy for cancer treatment. Glutamine addiction is a hallmark of many cancers. iMQT_020, a first-in-class allosteric inhibitor of the mitochondrial glutamine transporter SLC1A5_var, disrupts glutamine-dependent mitochondrial metabolism, selectively killing cancer cells and enhancing immune checkpoint inhibitor efficacy.

The mitochondrial glutamine transporter SLC1A5ᵥar plays a central role in the metabolic reprogramming of cancer cells by facilitating glutamine import into mitochondria for energy production and redox homeostasis. Despite its critical function, the development of effective and selective inhibitors targeting SLC1A5ᵥar has remained a significant challenge. Here, we introduce iMQT₀20, a selective allosteric inhibitor identified through structure-based screening. iMQT₀20 disrupts the trimeric assembly of SLC1A5ᵥar, causing metabolic crisis in cancer cells and selectively suppressing their growth. Mechanistically, iMQT₀20 reduces glutamine anaplerosis and oxidative phosphorylation, resulting in a broad disruption of cancer metabolism. Additionally, iMQT₀20 treatment epigenetically upregulates PD-L1 expression, enhancing the efficacy of combination therapies with anti-PD-L1 immune checkpoint inhibitors. These findings highlight the therapeutic potential of targeting SLC1A5ᵥar as a critical metabolic vulnerability in cancer and demonstrate that targeting allosteric interprotomer interactions is a novel and promising therapeutic strategy for cancer treatment. Glutamine addiction is a hallmark of many cancers. iMQT₀20, a first-in-class allosteric inhibitor of the mitochondrial glutamine transporter SLC1A5ᵥar, disrupts glutamine-dependent mitochondrial metabolism, selectively killing cancer cells and enhancing immune checkpoint inhibitor efficacy.

Aim： To investigate whether cytosolic heat shock protein 90 （HSP90） acts as a molecular chaperone on the activated extracellular signal-regulated kinase 1/2 （ERK1/2） and cell proliferation stimulated by reactive oxygen species （ROS） in rat vascular smooth muscle cells （VSMC）. Methods： VSMC were exposed to 1 pmol/L LY83583 （6-anilinoquinoline-5,8-quinolinedione, producer of ROS） for 120 min in the presence or absence of 5 μmol/L geldanamycin, a specific inhibitor of HSP90. Then the total, soluble, and insoluble proteins of the cells were collected. HSP90, ERK1/2, and phosphor-ERK 1/2 in the cell lysate were measured by Western blotting. The interaction of HSP90 and phosphor-ERK1/2 was analyzed by immunoprecipi- tation assay, and the nuclear phosphor-ERK1/2 was measured by Western blot- ting and immunofluorescence. Cell proliferation was tested by cell counting and 3-（4,5-dimethylthiazol-2-yl）-3,5-di-phenyltetrazoliumbromide （MTT）. Results： The cytosolic HSP90 of VSMC was upregulated by LY83583 in a time-dependent man- ner with the peak at 120 min, which is consistent with the late peak of phosphor- ERK1/2. Immunoprecipitation and Western blotting analyses showed that LY83583 increased the interaction of HSP90 with phosphor-ERK1/2, the phosphor-ERK1/2 level, and the soluble phosphor-ERK1/2 level by 1.8-, 2.5-, and 2.9-fold, respectively. In contrast, the insoluble phosphor-ERK1/2 of VSMC was decreased. Interestingly, LY83583 treatment promoted the nuclear phosphor-ERK1/2 by 7.6-fold as con- firmed by Western blotting and immunofluorescence assays. Furthermore, cell counting and the MTT assay showed that LY83583 stimulated VSMC prolifera- tion with the increased expression of HSP90 and levels of soluble and nuclear phosphor-ERK1/2. Pretreatment of geldanamycin antagonized the effect of LY83583. Conclusion： HSP90 could mediate the oxidative stress-stimulated, late- phase activation of ERK1/2 and VSMC proliferation by promoting the ERK1/2 phosphorylation, the association of itself with phosphor-ERK1/2, and the solubil- ity and nuclear translocation of phosphor-ERK 1/2.

The root of Polygonum multiflorum Thunb （PM） has been used in China to treat a variety of diseases, such as constipation, early graying of the hair and hyperlipemia. Recent evidence shows that PM causes idiosyncratic drug-induced liver injury （IDILI） in humans. In this study, we investigated the molecular basis of PM-induced liver injury in a rat model of IDILI based on a non-hepatotoxic dose of LPS. SD rats were orally administered 3 potentially hepatotoxic compounds of PM： cis-stilbene glucoside （cis-SG, 50 mg/kg）, trans-SG （50 mg/kg） or emodin （5 mg/kg）, followed by injection of LPS （2.8 mg/kg, iv）. Serum and liver histology were evaluated 7 h after LPS injection. Among the 3 compounds tested, cis-SG, but not emodin or trans-SG, induced severe liver injury in rats when combined with LPS. The levels of AST and ALT in plasma and inflammatory cytokines in both plasma and liver tissues were markedly elevated. The liver tissues showed increased injury, hepatocyte apoptosis, and macrophage infiltration, and decreased cell proliferation. Microarray analysis revealed a negative correlation between peroxisome proliferator-activated receptor-y （PPAR-y） and LPS/cis-SG-induced liver injury. Immunohistochemical staining and RT-PCR results further confirmed that cis-SG significantly inhibited activation of the PPAR-~ pathway in the liver tissues of LPS/cis-SG-treated rats. Pre-treatment with a PPAR-y agonist pioglitazone （500 g/kg, ig） reversed LPS/ cis-SG-induced liver injury, which was associated with inhibiting the nuclear factor kappa B （NF-KB） pathway. These data demonstrate that c/s-stilbene glucoside induces immunological idiosyncratic hepatotoxicity through suppressing PPAR-γ in a rat model of IDILl.

Renal tubulointerstitial fibrosis was a crucial pathological feature of diabetic nephropathy (DN), and renal tubular injury might associate with abnormal mitophagy. In this study, we investigated the effects and molecular mechanisms of AMPK agonist metformin on mitophagy and cellular injury in renal tubular cell under diabetic condition. The high fat diet (HFD) and streptozotocin (STZ)-induced type 2 diabetic mice model and HK-2 cells were used in this study. Metformin was administered in the drinking water (200 mg/kg/d) for 24 weeks. Renal tubulointerstitial lesions, oxidative stress and some indicators of mitophagy (e.g., LC3II, Pink1, and Parkin) were examined both in renal tissue and HK-2 cells. Additionally, compound C (an AMPK inhibitor) and Pink1 siRNA were applied to explore the molecular regulation mechanism of metformin on mitophagy. We found that the expression of p-AMPK, Pink1, Parkin, LC3II, and Atg5 in renal tissue of diabetic mice was decreased obviously. Metformin reduced the levels of serum creatinine, urine protein, and attenuated renal oxidative injury and fibrosis in HFD/STZ induced diabetic mice. In addition, Metformin reversed mitophagy dysfunction and the over-expression of NLRP3. In vitro pretreatment of HK-2 cells with AMPK inhibitor compound C or Pink1 siRNA negated the beneficial effects of metformin. Furthermore, we noted that metformin activated p-AMPK and promoted the translocation of Pink1 from the cytoplasm to mitochondria, then promoted the occurrence of mitophagy in HK-2 cells under HG/HFA ambience. Our results suggested for the first time that AMPK agonist metformin ameliorated renal oxidative stress and tubulointerstitial fibrosis in HFD/STZ-induced diabetic mice via activating mitophagy through a p-AMPK-Pink1-Parkin pathway.