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The Journal of Clinical Investigation Jan 2024Immunometabolism is a burgeoning field of research that investigates how immune cells harness nutrients to drive their growth and functions. Myeloid cells play a pivotal... (Review)
Review
Immunometabolism is a burgeoning field of research that investigates how immune cells harness nutrients to drive their growth and functions. Myeloid cells play a pivotal role in tumor biology, yet their metabolic influence on tumor growth and antitumor immune responses remains inadequately understood. This Review explores the metabolic landscape of tumor-associated macrophages, including the immunoregulatory roles of glucose, fatty acids, glutamine, and arginine, alongside the tools used to perturb their metabolism to promote antitumor immunity. The confounding role of metabolic inhibitors on our interpretation of myeloid metabolic phenotypes will also be discussed. A binary metabolic schema is currently used to describe macrophage immunological phenotypes, characterizing inflammatory M1 phenotypes, as supported by glycolysis, and immunosuppressive M2 phenotypes, as supported by oxidative phosphorylation. However, this classification likely underestimates the variety of states in vivo. Understanding these nuances will be critical when developing interventional metabolic strategies. Future research should focus on refining drug specificity and targeted delivery methods to maximize therapeutic efficacy.
Topics: Humans; Macrophages; Oxidative Phosphorylation; Myeloid Cells; Immunotherapy; Neoplasms
PubMed: 38226622
DOI: 10.1172/JCI175445 -
Molecular Cell Oct 2023The integrity of the nuclear envelope (NE) is essential for maintaining the structural stability of the nucleus. Rupture of the NE has been frequently observed in cancer...
The integrity of the nuclear envelope (NE) is essential for maintaining the structural stability of the nucleus. Rupture of the NE has been frequently observed in cancer cells, especially in the context of mechanical challenges, such as physical confinement and migration. However, spontaneous NE rupture events, without any obvious physical challenges to the cell, have also been described. The molecular mechanism(s) of these spontaneous NE rupture events remain to be explored. Here, we show that DNA damage and subsequent ATR activation leads to NE rupture. Upon DNA damage, lamin A/C is phosphorylated in an ATR-dependent manner, leading to changes in lamina assembly and, ultimately, NE rupture. In addition, we show that cancer cells with intrinsic DNA repair defects undergo frequent events of DNA-damage-induced NE rupture, which renders them extremely sensitive to further NE perturbations. Exploiting this NE vulnerability could provide a new angle to complement traditional, DNA-damage-based chemotherapy.
Topics: Nuclear Envelope; Lamin Type A; Phosphorylation; DNA Damage; DNA; Cell Nucleus
PubMed: 37832547
DOI: 10.1016/j.molcel.2023.09.023 -
Cell Dec 2023Molecular signals interact in networks to mediate biological processes. To analyze these networks, it would be useful to image many signals at once, in the same living...
Molecular signals interact in networks to mediate biological processes. To analyze these networks, it would be useful to image many signals at once, in the same living cell, using standard microscopes and genetically encoded fluorescent reporters. Here, we report temporally multiplexed imaging (TMI), which uses genetically encoded fluorescent proteins with different clocklike properties-such as reversibly photoswitchable fluorescent proteins with different switching kinetics-to represent different cellular signals. We linearly decompose a brief (few-second-long) trace of the fluorescence fluctuations, at each point in a cell, into a weighted sum of the traces exhibited by each fluorophore expressed in the cell. The weights then represent the signal amplitudes. We use TMI to analyze relationships between different kinase activities in individual cells, as well as between different cell-cycle signals, pointing toward broad utility throughout biology in the analysis of signal transduction cascades in living systems.
Topics: Animals; Humans; Mice; Cell Line; Fluorescent Dyes; Microscopy, Fluorescence; Phosphorylation; Proteins; Signal Transduction; Cell Survival
PubMed: 38029746
DOI: 10.1016/j.cell.2023.11.010 -
Viruses Dec 2023Mitochondria have been identified as the "powerhouse" of the cell, generating the cellular energy, ATP, for almost seven decades. Research over time has uncovered a... (Review)
Review
Mitochondria have been identified as the "powerhouse" of the cell, generating the cellular energy, ATP, for almost seven decades. Research over time has uncovered a multifaceted role of the mitochondrion in processes such as cellular stress signaling, generating precursor molecules, immune response, and apoptosis to name a few. Dysfunctional mitochondria resulting from a departure in homeostasis results in cellular degeneration. Viruses hijack host cell machinery to facilitate their own replication in the absence of a bonafide replication machinery. Replication being an energy intensive process necessitates regulation of the host cell oxidative phosphorylation occurring at the electron transport chain in the mitochondria to generate energy. Mitochondria, therefore, can be an attractive therapeutic target by limiting energy for viral replication. In this review we focus on the physiology of oxidative phosphorylation and on the limited studies highlighting the regulatory effects viruses induce on the electron transport chain.
Topics: Humans; Oxidative Phosphorylation; Mitochondria; Apoptosis; Signal Transduction; Virus Diseases; Phosphorylation; Oxidative Stress
PubMed: 38140621
DOI: 10.3390/v15122380 -
Proceedings of the National Academy of... Aug 2023To ensure optimal growth, plants actively regulate their growth and development based on environmental changes. Among these, salt stress significantly influences growth...
To ensure optimal growth, plants actively regulate their growth and development based on environmental changes. Among these, salt stress significantly influences growth and yield. In this study, we demonstrate that the growth of root hairs of salt-stressed seedlings is regulated by the SALT OVERLY SENSITIVE 2 (SOS2)-GUANOSINE NUCLEOTIDE DIPHOSPHATE DISSOCIATION INHIBITOR 1 (RhoGDI1)-Rho GTPASE OF PLANTS 2 (ROP2) module. We show here that the kinase SOS2 is activated by salt stress and subsequently phosphorylates RhoGDI1, a root hair regulator, thereby decreasing its stability. This change in RhoGDI1 abundance resulted in a fine-tuning of polar localization of ROP2 and root hair initiation followed by polar growth, demonstrating how SOS2-regulated root hair development is critical for plant growth under salt stress. Our results reveal how a tissue-specific response to salt stress balances the relationship of salt resistance and basic growth.
Topics: rho Guanine Nucleotide Dissociation Inhibitor alpha; Arabidopsis; Phosphorylation; Guanosine Diphosphate; Salt Stress
PubMed: 37590409
DOI: 10.1073/pnas.2217957120 -
Neuron Dec 2023Phosphorylation of α-synuclein at the serine-129 site (α-syn Ser129P) is an established pathologic hallmark of synucleinopathies and a therapeutic target. In...
Phosphorylation of α-synuclein at the serine-129 site (α-syn Ser129P) is an established pathologic hallmark of synucleinopathies and a therapeutic target. In physiologic states, only a fraction of α-syn is phosphorylated at this site, and most studies have focused on the pathologic roles of this post-translational modification. We found that unlike wild-type (WT) α-syn, which is widely expressed throughout the brain, the overall pattern of α-syn Ser129P is restricted, suggesting intrinsic regulation. Surprisingly, preventing Ser129P blocked activity-dependent synaptic attenuation by α-syn-thought to reflect its normal function. Exploring mechanisms, we found that neuronal activity augments Ser129P, which is a trigger for protein-protein interactions that are necessary for mediating α-syn function at the synapse. AlphaFold2-driven modeling and membrane-binding simulations suggest a scenario where Ser129P induces conformational changes that facilitate interactions with binding partners. Our experiments offer a new conceptual platform for investigating the role of Ser129 in synucleinopathies, with implications for drug development.
Topics: Humans; alpha-Synuclein; Phosphorylation; Parkinson Disease; Synucleinopathies; Serine
PubMed: 38128479
DOI: 10.1016/j.neuron.2023.11.020 -
Epigenetics & Chromatin Dec 2023Histones display a wide variety of post-translational modifications, including acetylation, methylation, and phosphorylation. These epigenetic modifications can... (Review)
Review
Histones display a wide variety of post-translational modifications, including acetylation, methylation, and phosphorylation. These epigenetic modifications can influence chromatin structure and function without altering the DNA sequence. Histones can also undergo post-translational O-GlcNAcylation, a rather understudied modification that plays critical roles in almost all biological processes and is added and removed by O-linked N-acetylglucosamine transferase and O-GlcNAcase, respectively. This review provides a current overview of our knowledge of how O-GlcNAcylation impacts the histone code both directly and by regulating other chromatin modifying enzymes. This highlights the pivotal emerging role of O-GlcNAcylation as an essential epigenetic marker.
Topics: Histones; Protein Processing, Post-Translational; Chromatin; Epigenesis, Genetic; Phosphorylation
PubMed: 38093337
DOI: 10.1186/s13072-023-00523-5 -
Nefrologia 2024Receptor interacting protein kinase 3 (RIPK3) is an intracellular kinase at the crossroads of cell death and inflammation. RIPK3 contains a RIP homotypic interaction... (Review)
Review
Receptor interacting protein kinase 3 (RIPK3) is an intracellular kinase at the crossroads of cell death and inflammation. RIPK3 contains a RIP homotypic interaction motif (RHIM) domain which allows interactions with other RHIM-containing proteins and a kinase domain that allows phosphorylation of target proteins. RIPK3 may be activated through interaction with RHIM-containing proteins such as RIPK1, TRIF and DAI (ZBP1, DLM-1) or through RHIM-independent mechanisms in an alkaline intracellular pH. RIPK3 mediates necroptosis and promotes inflammation, independently of necroptosis, through either activation of NFκB or the inflammasome. There is in vivo preclinical evidence of the contribution of RIPK3 to both acute kidney injury (AKI) and chronic kidney disease (CKD) and to the AKI-to-CKD transition derived from RIPK3 deficient mice or the use of small molecule RIPK3 inhibitors. In these studies, RIPK3 targeting decreased inflammation but kidney injury improved only in some contexts. Clinical translation of these findings has been delayed by the potential of some small molecule inhibitors of RIPK3 kinase activity to trigger apoptotic cell death by inducing conformational changes of the protein. A better understanding of the conformational changes in RIPK3 that trigger apoptosis, dual RIPK3/RIPK1 inhibitors or repurposing of multiple kinase inhibitors such as dabrafenib may facilitate clinical development of the RIPK3 inhibition concept for diverse inflammatory diseases, including kidney diseases.
Topics: Animals; Mice; Apoptosis; Phosphorylation; Inflammation; Acute Kidney Injury; Renal Insufficiency, Chronic
PubMed: 37150671
DOI: 10.1016/j.nefroe.2023.04.006 -
Cell Reports Dec 2023The phosphoinositide 3-kinase p110α is an essential mediator of insulin signaling and glucose homeostasis. We interrogated the human serine, threonine, and tyrosine...
The phosphoinositide 3-kinase p110α is an essential mediator of insulin signaling and glucose homeostasis. We interrogated the human serine, threonine, and tyrosine kinome to search for novel regulators of p110α and found that the Hippo kinases phosphorylate p110α at T1061, which inhibits its activity. This inhibitory state corresponds to a conformational change of a membrane-binding domain on p110α, which impairs its ability to engage membranes. In human primary hepatocytes, cancer cell lines, and rodent tissues, activation of the Hippo kinases MST1/2 using forskolin or epinephrine is associated with phosphorylation of T1061 and inhibition of p110α, impairment of downstream insulin signaling, and suppression of glycolysis and glycogen synthesis. These changes are abrogated when MST1/2 are genetically deleted or inhibited with small molecules or if the T1061 is mutated to alanine. Our study defines an inhibitory pathway of PI3K signaling and a link between epinephrine and insulin signaling.
Topics: Humans; Animals; Mice; Cell Line; Mice, Inbred C57BL; Male; Female; Epinephrine; Enzyme Activation; Protein Serine-Threonine Kinases; Phosphatidylinositols; Gene Deletion; Colforsin; Insulin; Phosphorylation; Hippo Signaling Pathway
PubMed: 38060450
DOI: 10.1016/j.celrep.2023.113535 -
Cell Death & Disease Jul 2023Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common genetic cause of Parkinson's disease (PD), with growing importance also for Crohn's...
Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common genetic cause of Parkinson's disease (PD), with growing importance also for Crohn's disease and cancer. LRRK2 is a large and complex protein possessing both GTPase and kinase activity. Moreover, LRRK2 activity and function can be influenced by its phosphorylation status. In this regard, many LRRK2 PD-associated mutants display decreased phosphorylation of the constitutive phosphorylation cluster S910/S935/S955/S973, but the role of these changes in phosphorylation status with respect to LRRK2 physiological functions remains unknown. Here, we propose that the S910/S935/S955/S973 phosphorylation sites act as key regulators of LRRK2-mediated autophagy under both basal and starvation conditions. We show that quadruple LRRK2 phosphomutant cells (4xSA; S910A/S935A/S955A/S973A) have impaired lysosomal functionality and fail to induce and proceed with autophagy during starvation. In contrast, treatment with the specific LRRK2 kinase inhibitors MLi-2 (100 nM) or PF-06447475 (150 nM), which also led to decreased LRRK2 phosphorylation of S910/S935/S955/S973, did not affect autophagy. In explanation, we demonstrate that the autophagy impairment due to the 4xSA LRRK2 phospho-dead mutant is driven by its enhanced LRRK2 kinase activity. We show mechanistically that this involves increased phosphorylation of LRRK2 downstream targets Rab8a and Rab10, as the autophagy impairment in 4xSA LRRK2 cells is counteracted by expression of phosphorylation-deficient mutants T72A Rab8a and T73A Rab10. Similarly, reduced autophagy and decreased LRRK2 phosphorylation at the constitutive sites were observed in cells expressing the pathological R1441C LRRK2 PD mutant, which also displays increased kinase activity. These data underscore the relation between LRRK2 phosphorylation at its constitutive sites and the importance of increased LRRK2 kinase activity in autophagy regulation and PD pathology.
Topics: Phosphorylation; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; Mutation; Autophagy; rab GTP-Binding Proteins
PubMed: 37454104
DOI: 10.1038/s41419-023-05964-0