The rockefeller university

Ferroptosis, a metabolic cell death process driven by iron-dependent phospholipid peroxidation, is implicated in various pathologies, including cancer. While metabolic factors such as glucose, lipids, and multiple amino acids have all been demonstrated to modulate ferroptosis, the role of oxygen, another fundamental metabolic component, in ferroptosis is not fully understood. Here, we show that cells acclimated to a low oxygen environment develop marked resistance to ferroptosis, and this resistance is independent of canonical oxygen-sensing pathway mediated by prolyl hydroxylases (PHDs) and HIF transcription factors. Instead, hypoxia suppresses ferroptosis by inhibiting KDM6A, a tumor suppressor and oxygen-dependent histone demethylase, leading to reduced expression of its transcriptional targets, including lipid metabolic enzymes ACSL4 and ETNK1, thus rewiring cellular phospholipid profile to a ferroptosis-resistant state. Relevant to cancer, pharmacological inhibition of the oncogenic histone methyltransferase EZH2, which opposes KDM6A activity, restored ferroptosis sensitivity of xenograft bladder tumor tissues harboring KDM6A mutation.

mRNA translation is rapidly upregulated after injury to supply proteins required for tissue regeneration. Augmented protein synthesis during regeneration has long been associated with increases in ribosome biogenesis and mTORC1 activity. Emerging evidence highlights the roles of multiple signaling pathways, RNA-binding proteins, and RNA modifications in tissue repair. Here, we review recent research on the molecular mechanisms underlying translational control in response to tissue damage. The findings underscore the importance of mRNA translation in regeneration and its potential therapeutic applications in tissue repair.

The Retroviridae are a family of viruses that reverse transcribe their RNA genome and integrate the resulting double-stranded DNA copy into the genome of the host cell. Retroviruses are well-documented pathogens that have been associated with a variety of diseases. The International Committee on Taxonomy of Viruses (ICTV) currently lists 65 species of retroviruses. As required by the ICTV, we have converted the species nomenclature to a binomial format comprised of the genus and a freeform epithet. Assigning binomial species names to classify new retroviruses will be facilitated when following the epithet rules described herein.

Bacterial sigma factors bind RNA polymerase (E) to form holoenzyme (E sigma), conferring promoter specificity to E and playing a key role in transcription bubble formation. sigma N is unique among sigma factors in its structure and functional mechanism, requiring activation by specialized AAA+ ATPases. E sigma N forms an inactive promoter complex where the N-terminal sigma N region I (sigma N-RI) threads through a small DNA bubble. On the opposite side of the DNA, the ATPase engages sigma N-RI within the pore of its hexameric ring. Here, we perform kinetics-guided structural analysis of de novo formed E sigma N initiation complexes and engineer a biochemical assay to measure ATPase-mediated sigma N-RI translocation during promoter melting. We show that the ATPase exerts mechanical action to translocate about 30 residues of sigma N-RI through the DNA bubble, disrupting inhibitory structures of sigma N to allow full transcription bubble formation. A local charge switch of sigma N-RI from positive to negative may help facilitate disengagement of the otherwise processive ATPase, allowing subsequent sigma N disentanglement from the DNA bubble.

Chronic inflammatory skin diseases arise from dysregulated interactions between tissue-resident and infiltrating cells, the complexity of which hinders disease understanding and treatment. To address this, here, we present a single-cell spatiotemporal atlas of murine type 2 skin inflammation using MERFISH and scRNA-seq. Analyzing similar to 430,000 cells during MC903-and oxazolone-induced dermatitis, we identify 39 cell types, including pro-inflammatory fibroblasts that resemble those in human atopic dermatitis. Spatial neighborhood analyses reveal basophils as potent activators of pro-inflammatory fibroblasts, with basophil-derived oncostatin-M (OSM) and IL-4 synergizing fibroblast-mediated feedforward basophil and immune recruitment. While fibroblast-specific deletion of the IL-4R alpha receptor disrupts inflammation in vivo, the addition of pharmacologic gp130 inhibition, a core component of the OSM receptor, results in synergistic reduction of inflammation. Our study establishes a basophil-fibroblast circuitry as a critical regulator of type 2 skin inflammation, redefining basophil biology and positioning fibroblasts as dynamic immune regulators and therapeutic targets in inflammatory skin disease.

Proper fuelling of the brain is critical to sustain cognitive function, but the role of fatty acid (FA) combustion in this process has been elusive. Here we show that acute block of a neuron-specific triglyceride lipase, DDHD2 (a genetic driver of complex hereditary spastic paraplegia), or of the mitochondrial lipid transporter CPT1 leads to rapid onset of torpor in adult male mice. These data indicate that in vivo neurons are probably constantly fluxing FAs derived from lipid droplets (LDs) through beta-oxidation to support neuronal bioenergetics. We show that in dissociated neurons, electrical silencing or blocking of DDHD2 leads to accumulation of neuronal LDs, including at nerve terminals, and that FAs derived from axonal LDs enter mitochondria in an activity-dependent fashion to drive local mitochondrial ATP production. These data demonstrate that nerve terminals can make use of LDs during electrical activity to provide metabolic support and probably have a critical role in supporting neuron function in vivo.

Isocitrate dehydrogenase 1/2 (IDH) mutations are early initiating events in acute myeloid leukemia (AML). The complex clonal architecture and cellular heterogeneity in IDH-mutant AML underlies the heterogeneous clinical presentation and outcomes. Integrating single-cell genotyping and transcriptomics, we demonstrate a stem-like and inflammatory phenotype of IDH-mutant AML and identify clone-specific programs associated with NPM1, NRAS, and SRSF2 co-mutations. Furthermore, these clones had distinct responses to treatment with combination IDH inhibitors and chemotherapy, including elimination, reconstitution of myeloid differentiation, or retention within progenitor populations. At relapse after IDH inhibitor monotherapy, we identify up-regulated stemness, inflammation, mitochondrial metabolism, and anti-apoptotic factors, as well as down-regulated major histocompatibility complex (MHC) class II antigen presentation. At the pre-leukemic stage, we observe upregulation of IDH2-associated pathways, including inflammation. We deliver a detailed phenotyping of IDH-mutant AML and a framework for dissecting contributions of recurrently mutated genes in AML at diagnosis and following therapy, with implications for precision medicine.

A critical component of the function of IgG antibodies is their capacity to engage specialized cellular receptors, Fc gamma receptors (Fc gamma Rs), expressed on effector leukocytes. Highlighting the importance of Fc gamma R-mediated signaling in the regulation of the fate, activation, and differentiation status of leukocytes, Fc gamma Rs are ubiquitously expressed by nearly all leukocyte populations. Here, we report that while at steady state, T cells are negative for all classes of Fc gamma Rs, CD8 T cells specifically induce the expression of the activating Fc gamma R, Fc gamma RIIIa, in response to viral infection in cohorts of COVID-19 and dengue patients, as well as in virus infection models using Fc gamma R humanized mouse strains. In in vivo mechanistic studies, we demonstrate that induction of Fc gamma RIIIa expression on effector CD8 T cells follows a well-defined trajectory that closely tracks the course and magnitude of the immune response, while immune resolution is characterized by receptor downregulation. Uniquely to these CD8 T cells, Fc gamma RIIIa crosslinking alone is paradoxically insufficient to elicit T cell activation and cytotoxicity. However, when coupled with T cell receptor (TCR) stimulation, it results in synergistic cellular activation and, compensates for the downregulation of canonical costimulatory molecules on terminal effector CD8 T cells. These results reveal a previously unappreciated role for Fc gamma RIIIa as a unique costimulatory molecule that synergizes with TCR signaling to lower the effective threshold required for CD8 T cell activation, highlighting the role of virally induced antibodies in modulating CD8 effector cell responses.

Clinical and animal studies suggest that multiple brain systems are involved in mediating reward-motivated and related emotional behavior including the consumption of commonly used drugs and palatable food, and there is evidence that the repeated ingestion of or exposure to these rewarding substances may in turn stimulate these brain systems to produce an overconsumption of these substances along with co-occurring emotional disturbances. To understand this positive feedback loop, this review focuses on a specific population of hypothalamic peptide neurons expressing melanin-concentrating hormone (MCH), which are positively related to dopamine reward and project to forebrain areas that mediate this behavior. It also examines neurons expressing the peptide hypocretin/orexin (HCRT) that are anatomically and functionally linked to MCH neurons and the molecular systems within these peptide neurons that stimulate their development and ultimately affect behavior. This report first describes evidence in animals that exposure in adults and during adolescence to rewarding substances, such as the drugs alcohol, nicotine and cocaine and palatable fat-rich food, stimulates the expression of MCH as well as HCRT and their intracellular molecular systems. It also increases reward-seeking and emotional behavior, leading to excess consumption and abuse of these substances and neurological conditions, completing this positive feedback loop. Next, this review focuses on the model involving embryonic exposure to these rewarding substances. In addition to revealing a similar positive feedback circuit, this model greatly advances our understanding of the diverse changes that occur in these neuropeptide/molecular systems in the embryo and how they relate, perhaps causally, to the disturbances in behavior early in life that predict a later increased risk of developing substance use disorders. Studies using this model demonstrate in animals that embryonic exposure to these rewarding substances, in addition to stimulating the expression of peptide neurons, increases the intracellular molecular systems in neuroprogenitor cells that promote their development. It also alters the morphology, migration, location and neurochemical profile of the peptide neurons and causes them to develop aberrant neuronal projections to forebrain structures. Moreover, it produces disturbances in behavior at a young age, which are sex-dependent and occur in females more than in males, that can be directly linked to the neuropeptide/molecular changes in the embryo and predict the development of behavioral disorders later in life. These results supporting the close relationship between the brain and behavior are consistent with clinical studies, showing females to be more vulnerable than males to developing substance use disorders with co-occurring emotional conditions and female offspring to respond more adversely than male offspring to prenatal exposure to rewarding substances. It is concluded that the continued consumption of or exposure to rewarding substances at any stage of life can, through such peptide brain systems, significantly increase an individual's vulnerability to developing neurological disorders such as substance use disorders, anxiety, depression, or cognitive impairments.

While human and mouse memory B cells (MBCs) can express the transcription factor T-bet, its role in regulating MBC function remains unclear. We characterized multiple transcriptionally distinct clusters of mature, somatically mutated nucleoprotein (NP)-specific MBCs in lymph nodes (LNs) and lungs of influenza-infected mice. Although none of the MBCs expressed the plasma cell (PC) lineage commitment factor Blimp1, one cluster was enriched for Tbx21+ cells. Similar to the previously described human T-bet + effector MBC (eMBC) population, Tbx21+ mouse MBCs upregulated gene networks associated with effector metabolism, protein synthesis, and the unfolded protein response. Constitutive and inducible ablation of T-bet in murine B cells showed that T-bet expression by MBCs was required for persistence of LN and lung eMBCs with rapid in vitro and in vivo PC differentiation potential. Thus, T-bet marks NP + eMBCs that are poised to differentiate, and it regulates maintenance of lung-resident MBCs and local PC responses following virus re-exposure.