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Molecular Cancer Aug 2023The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle... (Review)
Review
The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle progression. Growth factor signalling to transcription factors in the PAM axis is highly regulated by multiple cross-interactions with several other signaling pathways, and dysregulation of signal transduction can predispose to cancer development. The PAM axis is the most frequently activated signaling pathway in human cancer and is often implicated in resistance to anticancer therapies. Dysfunction of components of this pathway such as hyperactivity of PI3K, loss of function of PTEN, and gain-of-function of AKT, are notorious drivers of treatment resistance and disease progression in cancer. In this review we highlight the major dysregulations in the PAM signaling pathway in cancer, and discuss the results of PI3K, AKT and mTOR inhibitors as monotherapy and in co-administation with other antineoplastic agents in clinical trials as a strategy for overcoming treatment resistance. Finally, the major mechanisms of resistance to PAM signaling targeted therapies, including PAM signaling in immunology and immunotherapies are also discussed.
Topics: Humans; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; TOR Serine-Threonine Kinases; Neoplasms
PubMed: 37596643
DOI: 10.1186/s12943-023-01827-6 -
Cell Metabolism Apr 2024Utilization of lipids as energy substrates after birth causes cardiomyocyte (CM) cell-cycle arrest and loss of regenerative capacity in mammalian hearts. Beyond energy...
Utilization of lipids as energy substrates after birth causes cardiomyocyte (CM) cell-cycle arrest and loss of regenerative capacity in mammalian hearts. Beyond energy provision, proper management of lipid composition is crucial for cellular and organismal health, but its role in heart regeneration remains unclear. Here, we demonstrate widespread sphingolipid metabolism remodeling in neonatal hearts after injury and find that SphK1 and SphK2, isoenzymes producing the same sphingolipid metabolite sphingosine-1-phosphate (S1P), differently regulate cardiac regeneration. SphK2 is downregulated during heart development and determines CM proliferation via nuclear S1P-dependent modulation of histone acetylation. Reactivation of SphK2 induces adult CM cell-cycle re-entry and cytokinesis, thereby enhancing regeneration. Conversely, SphK1 is upregulated during development and promotes fibrosis through an S1P autocrine mechanism in cardiac fibroblasts. By fine-tuning the activity of each SphK isoform, we develop a therapy that simultaneously promotes myocardial repair and restricts fibrotic scarring to regenerate the infarcted adult hearts.
Topics: Animals; Sphingolipids; Heart; Sphingosine; Isoenzymes; Mammals; Phosphotransferases (Alcohol Group Acceptor); Lysophospholipids
PubMed: 38367623
DOI: 10.1016/j.cmet.2024.01.017 -
Cell Metabolism Dec 2023Mammalian target of rapamycin complex 1 (mTORC1) monitors cellular amino acid changes for function, but the molecular mediators of this process remain to be fully...
Mammalian target of rapamycin complex 1 (mTORC1) monitors cellular amino acid changes for function, but the molecular mediators of this process remain to be fully defined. Here, we report that depletion of cellular amino acids, either alone or in combination, leads to the ubiquitination of mTOR, which inhibits mTORC1 kinase activity by preventing substrate recruitment. Mechanistically, amino acid depletion causes accumulation of uncharged tRNAs, thereby stimulating GCN2 to phosphorylate FBXO22, which in turn accrues in the cytoplasm and ubiquitinates mTOR at Lys2066 in a K27-linked manner. Accordingly, mutation of mTOR Lys2066 abolished mTOR ubiquitination in response to amino acid depletion, rendering mTOR insensitive to amino acid starvation both in vitro and in vivo. Collectively, these data reveal a novel mechanism of amino acid sensing by mTORC1 via a previously unknown GCN2-FBXO22-mTOR pathway that is uniquely controlled by uncharged tRNAs.
Topics: Protein Serine-Threonine Kinases; TOR Serine-Threonine Kinases; Amino Acids; RNA, Transfer; Mechanistic Target of Rapamycin Complex 1
PubMed: 37979583
DOI: 10.1016/j.cmet.2023.10.016 -
Nature Neuroscience Dec 2023It is generally thought that under basal conditions, neurons produce ATP mainly through mitochondrial oxidative phosphorylation (OXPHOS), and glycolytic activity only...
It is generally thought that under basal conditions, neurons produce ATP mainly through mitochondrial oxidative phosphorylation (OXPHOS), and glycolytic activity only predominates when neurons are activated and need to meet higher energy demands. However, it remains unknown whether there are differences in glucose metabolism between neuronal somata and axon terminals. Here, we demonstrated that neuronal somata perform higher levels of aerobic glycolysis and lower levels of OXPHOS than terminals, both during basal and activated states. We found that the glycolytic enzyme pyruvate kinase 2 (PKM2) is localized predominantly in the somata rather than in the terminals. Deletion of Pkm2 in mice results in a switch from aerobic glycolysis to OXPHOS in neuronal somata, leading to oxidative damage and progressive loss of dopaminergic neurons. Our findings update the conventional view that neurons uniformly use OXPHOS under basal conditions and highlight the important role of somatic aerobic glycolysis in maintaining antioxidant capacity.
Topics: Animals; Mice; Oxidative Phosphorylation; Glycolysis; Phosphotransferases; Oxidative Stress; Glucose
PubMed: 37996529
DOI: 10.1038/s41593-023-01476-4 -
Science Advances Sep 2023EGFR-ERK signaling controls cell cycle progression during development, homeostasis, and disease. While EGF ligand and mechanical inputs can activate EGFR-ERK signaling,...
EGFR-ERK signaling controls cell cycle progression during development, homeostasis, and disease. While EGF ligand and mechanical inputs can activate EGFR-ERK signaling, the molecules linking mechanical force to this axis have remained mysterious. We previously found that stretch promotes mitosis via the stretch-activated ion channel Piezo1 and ERK signaling. Here, we show that Piezo1 provides the missing link between mechanical signals and EGFR-ERK activation. While both EGF- and Piezo1-dependent activation trigger clathrin-mediated EGFR endocytosis and ERK activation, EGF relies on canonical tyrosine autophosphorylation, whereas Piezo1 involves Src-p38 kinase-dependent serine phosphorylation. In addition, unlike EGF, ex vivo lung slices treated with Piezo1 agonist promoted cell cycle re-entry via nuclear ERK, AP-1 (FOS and JUN), and YAP accumulation, typical of regenerative and malignant signaling. Our results suggest that mechanical activation via Piezo1, Src, and p38 may be more relevant to controlling repair, regeneration, and cancer growth than tyrosine kinase signaling via canonical EGF signaling, suggesting an alternative therapeutic approach.
Topics: Epidermal Growth Factor; Signal Transduction; src-Family Kinases; Endocytosis; Mitosis; ErbB Receptors
PubMed: 37756411
DOI: 10.1126/sciadv.adi1328 -
Pharmacological Research Feb 2024Owing to the dysregulation of protein kinase activity in many diseases including cancer, this enzyme family has become one of the most important drug targets in the 21st... (Review)
Review
Owing to the dysregulation of protein kinase activity in many diseases including cancer, this enzyme family has become one of the most important drug targets in the 21st century. There are 80 FDA-approved therapeutic agents that target about two dozen different protein kinases and seven of these drugs were approved in 2023. Of the approved drugs, thirteen target protein-serine/threonine protein kinases, four are directed against dual specificity protein kinases (MEK1/2), twenty block nonreceptor protein-tyrosine kinases, and 43 inhibit receptor protein-tyrosine kinases. The data indicate that 69 of these drugs are prescribed for the treatment of neoplasms. Six drugs (abrocitinib, baricitinib, deucravacitinib, ritlecitinib, tofacitinib, upadacitinib) are used for the treatment of inflammatory diseases (atopic dermatitis, rheumatoid arthritis, psoriasis, alopecia areata, and ulcerative colitis). Of the 80 approved drugs, nearly two dozen are used in the treatment of multiple diseases. The following seven drugs received FDA approval in 2023: capivasertib (HER2-positive breast cancer), fruquintinib (metastatic colorectal cancer), momelotinib (myelofibrosis), pirtobrutinib (mantle cell lymphoma, chronic lymphocytic leukemia, small lymphocytic lymphoma), quizartinib (Flt3-mutant acute myelogenous leukemia), repotrectinib (ROS1-positive lung cancer), and ritlecitinib (alopecia areata). All of the FDA-approved drugs are orally effective with the exception of netarsudil, temsirolimus, and trilaciclib. This review summarizes the physicochemical properties of all 80 FDA-approved small molecule protein kinase inhibitors including the molecular weight, number of hydrogen bond donors/acceptors, polar surface area, potency, solubility, lipophilic efficiency, and ligand efficiency.
Topics: Humans; Adult; Protein Kinase Inhibitors; Alopecia Areata; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Protein Serine-Threonine Kinases; Protein Kinases; Neoplasms
PubMed: 38216005
DOI: 10.1016/j.phrs.2024.107059 -
Cardiovascular Research Jul 2023Positive associations between periodontitis (PD) and atherosclerosis have been established, but the causality and mechanisms are not clear. We aimed to explore the...
AIMS
Positive associations between periodontitis (PD) and atherosclerosis have been established, but the causality and mechanisms are not clear. We aimed to explore the causal roles of PD in atherosclerosis and dissect the underlying mechanisms.
METHODS AND RESULTS
A mouse model of PD was established by ligation of molars in combination with application of subgingival plaques collected from PD patients and then combined with atherosclerosis model induced by treating atheroprone mice with a high-cholesterol diet (HCD). PD significantly aggravated atherosclerosis in HCD-fed atheroprone mice, including increased en face plaque areas in whole aortas and lesion size at aortic roots. PD also increased circulating levels of triglycerides and cholesterol, hepatic levels of cholesterol, and hepatic expression of rate-limiting enzymes for lipogenesis. Using 16S ribosomal RNA (rRNA) gene sequencing, Fusobacterium nucleatum was identified as the most enriched PD-associated pathobiont that is present in both the oral cavity and livers. Co-culture experiments demonstrated that F. nucleatum directly stimulated lipid biosynthesis in primary mouse hepatocytes. Moreover, oral inoculation of F. nucleatum markedly elevated plasma levels of triglycerides and cholesterol and promoted atherogenesis in HCD-fed ApoE-/- mice. Results of RNA-seq and Seahorse assay indicated that F. nucleatum activated glycolysis, inhibition of which by 2-deoxyglucose in turn suppressed F. nucleatum-induced lipogenesis in hepatocytes. Finally, interrogation of the molecular mechanisms revealed that F. nucleatum-induced glycolysis and lipogenesis by activating PI3K/Akt/mTOR signalling pathway in hepatocytes.
CONCLUSIONS
PD exacerbates atherosclerosis and impairs lipid metabolism in mice, which may be mediated by F. nucleatum-promoted glycolysis and lipogenesis through PI3K/Akt/mTOR signalling in hepatocytes. Treatment of PD and specific targeting of F. nucleatum are promising strategies to improve therapeutic effectiveness of hyperlipidaemia and atherosclerosis.
Topics: Mice; Animals; Fusobacterium nucleatum; Lipogenesis; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Mice, Knockout, ApoE; Periodontitis; Atherosclerosis; Liver; Triglycerides; TOR Serine-Threonine Kinases
PubMed: 36943793
DOI: 10.1093/cvr/cvad045 -
Cancer Discovery Sep 2023Facchinetti and colleagues provide key insights into the evolution of resistance to fibroblast growth factor receptor (FGFR) inhibitors, including the development of...
Facchinetti and colleagues provide key insights into the evolution of resistance to fibroblast growth factor receptor (FGFR) inhibitors, including the development of kinase domain mutations and activation of the PI3K-AKT signaling axis. In a separate study, Subbiah and colleagues report extensive preclinical data and initial clinical data for RLY-4008, an FGFR2-selective inhibitor that is poised to minimize toxicity and overcome resistance through greater potency and selectivity. See related article by Facchinetti et al., p. 1998 (5). See related article by Subbiah et al., p. 2012 (7).
Topics: Humans; Phosphatidylinositol 3-Kinases; Mutation; Protein Kinase Inhibitors; Receptor, Fibroblast Growth Factor, Type 2
PubMed: 37671472
DOI: 10.1158/2159-8290.CD-23-0728 -
Cell Jan 2024The FERONIA (FER)-LLG1 co-receptor and its peptide ligand RALF regulate myriad processes for plant growth and survival. Focusing on signal-induced cell surface...
The FERONIA (FER)-LLG1 co-receptor and its peptide ligand RALF regulate myriad processes for plant growth and survival. Focusing on signal-induced cell surface responses, we discovered that intrinsically disordered RALF triggers clustering and endocytosis of its cognate receptors and FER- and LLG1-dependent endocytosis of non-cognate regulators of diverse processes, thus capable of broadly impacting downstream responses. RALF, however, remains extracellular. We demonstrate that RALF binds the cell wall polysaccharide pectin. They phase separate and recruit FER and LLG1 into pectin-RALF-FER-LLG1 condensates to initiate RALF-triggered cell surface responses. We show further that two frequently encountered environmental challenges, elevated salt and temperature, trigger RALF-pectin phase separation, promiscuous receptor clustering and massive endocytosis, and that this process is crucial for recovery from stress-induced growth attenuation. Our results support that RALF-pectin phase separation mediates an exoskeletal mechanism to broadly activate FER-LLG1-dependent cell surface responses to mediate the global role of FER in plant growth and survival.
Topics: Phosphotransferases; Arabidopsis Proteins; Arabidopsis; Pectins; Phase Separation; GPI-Linked Proteins
PubMed: 38157854
DOI: 10.1016/j.cell.2023.11.038 -
Aging Cell Jul 2023Mitochondrial dysfunction is considered to be an important mediator of the pro-aging process in chronic kidney disease, which is continuously increasing worldwide....
Mitochondrial dysfunction is considered to be an important mediator of the pro-aging process in chronic kidney disease, which is continuously increasing worldwide. Although PTEN-induced kinase 1 (PINK1) regulates mitochondrial function, its role in renal aging remains unclear. We investigated the association between PINK1 and renal aging, especially through the cGAS-STING pathway, which is known to result in an inflammatory phenotype. Pink1 knockout (Pink1 ) C57BL/6 mice and senescence-induced renal tubular epithelial cells (HKC-8) treated with H O were used as the renal aging models. Extensive analyses at transcriptomic-metabolic levels have explored changes in mitochondrial function in PINK1 deficiency. To investigate whether PINK1 deficiency affects renal aging through the cGAS-STING pathway, we explored their expression levels in PINK1 knockout mice and senescence-induced HKC-8 cells. PINK1 deficiency enhances kidney fibrosis and tubular injury, and increases senescence and the senescence-associated secretory phenotype (SASP). These phenomena were most apparent in the 24-month-old Pink1 mice and HKC-8 cells treated with PINK1 siRNA and H O . Gene expression analysis using RNA sequencing showed that PINK1 deficiency is associated with increased inflammatory responses, and transcriptomic and metabolomic analyses suggested that PINK1 deficiency is related to mitochondrial metabolic dysregulation. Activation of cGAS-STING was prominent in the 24-month-old Pink1 mice. The expression of SASPs was most noticeable in senescence-induced HKC-8 cells and was attenuated by the STING inhibitor, H151. PINK1 is associated with renal aging, and mitochondrial dysregulation by PINK1 deficiency might stimulate the cGAS-STING pathway, eventually leading to senescence-related inflammatory responses.
Topics: Animals; Mice; Aging; Kidney; Mice, Inbred C57BL; Nucleotidyltransferases; Protein Kinases
PubMed: 37183600
DOI: 10.1111/acel.13865