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The majority of viruses classified as pandemic threats are enveloped viruses which enter the cell through receptor-mediated endocytosis and take advantage of endosomal acidification to activate their fusion machinery. Here we report that the endosomal fusion of low pH-requiring viruses is highly dependent on TRPM7, a widely expressed TRP channel that is located on the plasma membrane and in intracellular vesicles. Using several viral infection systems expressing the envelope glycoproteins of various viruses, we find that loss of TRPM7 protects cells from infection by Lassa, LCMV, Ebola, Influenza, MERS, SARS-CoV-1, and SARS-CoV-2. TRPM7 ion channel activity is intrinsically necessary to acidify virus-laden endosomes but is expendable for several other endosomal acidification pathways. We propose a model wherein TRPM7 ion channel activity provides a countercurrent of cations from endosomal lumen to cytosol necessary to sustain the pumping of protons into these virus-laden endosomes. This study demonstrates the possibility of developing a broad-spectrum, TRPM7-targeting antiviral drug to subvert the endosomal fusion of low pH-dependent enveloped viruses., (© 2024. The Author(s).)

Optic neuritis (ON) is a debilitating condition that through various mechanisms, including inflammation or demyelination of the optic nerve, can result in partial or total permanent vision loss if left untreated. Accurate diagnosis and promptly initiated treatment are imperative related to the potential of permanent loss of vision if left untreated, which can lead to a significant reduction in the quality of life in affected patients. ON is subtyped as "typical" or "atypical" based on underlying causative etiology. The etiology of ON can be differentiated when appropriate diagnostic testing is performed. Using history taking, neuroimaging, and visual testing to localize the underlying pathology of ON in a time-sensitive manner is critical in mitigating these unsatisfactory outcomes. Herein, we examine the differences in presentation, pathophysiology, and treatments of typical ON causes, like multiple sclerosis (MS), and atypical causes such as neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein (MOG)-immunoglobulin G (IgG) ON. The present investigation places focus on both neuroimaging and visual imaging in the differentiation of ON. Additionally, this review presents physicians with a better understanding of different presentations, treatments, and prognoses of ON., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Spillers et al.)

Insulin secretion depends on the Ca 2+ -regulated fusion of granules with the plasma membrane. A recent model of Ca 2+ -triggered exocytosis in secretory cells proposes that lipids in the plasma membrane couple the calcium sensor Syt1 to the membrane fusion machinery (Kiessling et al. , 2018). Specifically, Ca 2+ -mediated binding of Syt1's C2 domains to the cell membrane shifts the membrane-anchored SNARE syntaxin-1a to a more fusogenic conformation, straightening its juxtamembrane linker. To test this model in live cells and extend it to insulin secretion, we enriched INS1 cells with a panel of lipids with different acyl chain compositions. Fluorescence lifetime measurements demonstrate that cells with more disordered membranes show an increase in fusion efficiency, and vice versa. Experiments with granules purified from INS1 cells and recombinant SNARE proteins reconstituted in supported membranes confirmed that lipid acyl chain composition determines SNARE conformation and that lipid disordering correlates with increased fusion. Addition of Syt1's C2AB domains significantly decreased lipid order in target membranes and increased SNARE-mediated fusion probability. Strikingly, Syt's action on both fusion and lipid order could be partially bypassed by artificially increasing unsaturated phosphatidylserines in the target membrane. Thus, plasma membrane lipids actively participate in coupling Ca 2+ /synaptotagmin-sensing to the SNARE fusion machinery in cells.

TRPM7, a TRP channel with ion conductance and kinase activities, has emerged as an attractive drug target for immunomodulation. Reverse genetics and cell biological studies have already established a key role for TRPM7 in the inflammatory activation of macrophages. Advancing TRPM7 as a viable molecular target for immunomodulation requires selective TRPM7 inhibitors with in vivo tolerability and efficacy. Such inhibitors have the potential to interdict inflammatory cascades mediated by systemic and tissue-specialized macrophages. FTY720, an FDA-approved drug for multiple sclerosis inhibits TRPM7. However, FTY720 is a prodrug and its metabolite, FTY720-phosphate, is a potent agonist of sphingosine-1-phosphate (S1P) receptors. In this study, we test non-phosphorylatable FTY720 analogs, which are inert against S1PRs and well tolerated in vivo, for activity against TRPM7 and tissue bioavailability. Using patch clamp electrophysiology, we show that VPC01091.4 and AAL-149 block TRPM7 current at low micromolar concentrations. In culture, they act directly on macrophages to blunt LPS-induced inflammatory cytokine expression, though this likely occurrs through multiple molecular targets. We found that VPC01091.4 has significant and rapid accumulation in the brain and lungs, along with direct anti-inflammatory action on alveolar macrophages and microglia. Finally, using a mouse model of endotoxemia, we show VPC01091.4 to be an efficacious anti-inflammatory agent that arrests systemic inflammation in vivo. Together, these findings identify novel small molecule inhibitors that allow TRPM7 channel inhibition independent of S1P receptor targeting which demonstrate potent, polymodal anti-inflammatory activities ex vivo and in vivo., (© 2023 Busey et al.)

Variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) challenge currently available coronavirus disease 2019 vaccines and monoclonal antibody therapies through epitope change on the receptor binding domain of the viral spike glycoprotein. Hence, there is a specific urgent need for alternative antivirals that target processes less likely to be affected by mutation, such as the membrane fusion step of viral entry into the host cell. One such antiviral class includes peptide inhibitors, which block formation of the so-called heptad repeat 1 and 2 (HR1HR2) six-helix bundle of the SARS-CoV-2 spike (S) protein and thus interfere with viral membrane fusion. We performed structural studies of the HR1HR2 bundle, revealing an extended, well-folded N-terminal region of HR2 that interacts with the HR1 triple helix. Based on this structure, we designed an extended HR2 peptide that achieves single-digit nanomolar inhibition of SARS-CoV-2 in cell-based and virus-based assays without the need for modifications such as lipidation or chemical stapling. The peptide also strongly inhibits all major SARS-CoV-2 variants to date. This extended peptide is ∼100-fold more potent than all previously published short, unmodified HR2 peptides, and it has a very long inhibition lifetime after washout in virus infection assays, suggesting that it targets a prehairpin intermediate of the SARS-CoV-2 S protein. Together, these results suggest that regions outside the HR2 helical region may offer new opportunities for potent peptide-derived therapeutics for SARS-CoV-2 and its variants, and even more distantly related viruses, and provide further support for the prehairpin intermediate of the S protein.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cell entry starts with membrane attachment and ends with spike (S) protein-catalyzed membrane fusion depending on two cleavage steps, namely, one usually by furin in producing cells and the second by TMPRSS2 on target cells. Endosomal cathepsins can carry out both. Using real-time three-dimensional single-virion tracking, we show that fusion and genome penetration require virion exposure to an acidic milieu of pH 6.2 to 6.8, even when furin and TMPRSS2 cleavages have occurred. We detect the sequential steps of S1-fragment dissociation, fusion, and content release from the cell surface in TMPRRS2-overexpressing cells only when exposed to acidic pH. We define a key role of an acidic environment for successful infection, found in endosomal compartments and at the surface of TMPRSS2-expressing cells in the acidic milieu of the nasal cavity.

Efficient clearance of apoptotic cells by phagocytosis, also known as efferocytosis, is fundamental to developmental biology, organ physiology, and immunology. Macrophages use multiple mechanisms to detect and engulf apoptotic cells, but the signaling pathways that regulate the digestion of the apoptotic cell cargo, such as the dynamic Ca 2+ signals, are poorly understood. Using an siRNA screen, we identify TRPM7 as a Ca 2+ -conducting ion channel essential for phagosome maturation during efferocytosis. Trpm7-targeted macrophages fail to fully acidify or digest their phagosomal cargo in the absence of TRPM7. Through perforated patch electrophysiology, we demonstrate that TRPM7 mediates a pH-activated cationic current necessary to sustain phagosomal acidification. Using mice expressing a genetically-encoded Ca 2+ sensor, we observe that phagosome maturation requires peri-phagosomal Ca 2+ -signals dependent on TRPM7. Overall, we reveal TRPM7 as a central regulator of phagosome maturation during macrophage efferocytosis., (© 2022. The Author(s).)

Background: A gender-based compensation gap among physicians is well documented. Even after adjusting for age, experience, work hours, productivity, and academic rank, the gender gap remained and widened over the course of a physician's career. This study aimed to examine if a significant gender pay gap still existed for anesthesiologists in the United States., Methods: In 2018, we surveyed 28,812 physician members of the American Society of Anesthesiologists to assess the association of compensation with gender and to identify possible causes of wage disparities. Gender was the primary variable examined in the model, and compensation by gender was the primary outcome. Compensation was defined as the amount reported as direct compensation on a W-2, 1099, or K-1, plus all voluntary salary reductions (eg, 401[k], health insurance). The survey directed respondents to include salary, bonuses, incentive payments, research stipends, honoraria, and distribution of profits to employees. Respondents had the option of providing a point estimate of their compensation or selecting a range in $50,000 increments. Potential confounding variables that could affect compensation were identified based on a scoping literature review and the consensus expertise of the authors. We fitted a generalized ordinal logistic regression with 7 ranges of compensation. For the sensitivity analyses, we used linear regressions of log-transformed compensation based on respondent point estimates and imputed values., Results: The final analytic sample consisted of 2081 observations (response rate, 7.2%). This sample represented a higher percentage of women and younger physicians compared to the demographic makeup of anesthesiologists in the United States. The adjusted odds ratio associated with gender equal to woman was an estimated 0.44 (95% confidence interval, 0.37-0.53), indicating that for a given compensation range, women had a 56% lower odds than men of being in a higher compensation range. Sensitivity analyses found the relative percentage difference in compensation for women compared to men ranged from -8.3 to -8.9. In the sensitivity analysis based on the subset of respondents (n = 1036) who provided a point estimate of compensation, the relative percentage difference (-8.3%; 95% confidence interval, -4.7 to -11.7) reflected a $32,617 lower compensation for women than men, holding other covariates at their means., Conclusions: Compensation for anesthesiologists showed a significant pay gap that was associated with gender even after adjusting for potential confounding factors, including age, hours worked, geographic practice region, practice type, position, and job selection criteria., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 International Anesthesia Research Society.)

Activation of Pannexin 1 (PANX1) ion channels causes release of intercellular signaling molecules in a variety of (patho)physiological contexts. PANX1 can be activated by G protein-coupled receptors (GPCRs), including α1-adrenergic receptors (α1-ARs), but how receptor engagement leads to channel opening remains unclear. Here, we show that GPCR-mediated PANX1 activation can occur via channel deacetylation. We find that α1-AR-mediated activation of PANX1 channels requires Gαq but is independent of phospholipase C or intracellular calcium. Instead, α1-AR-mediated PANX1 activation involves RhoA, mammalian diaphanous (mDia)-related formin, and a cytosolic lysine deacetylase activated by mDia - histone deacetylase 6. HDAC6 associates with PANX1 and activates PANX1 channels, even in excised membrane patches, suggesting direct deacetylation of PANX1. Substitution of basally-acetylated intracellular lysine residues identified on PANX1 by mass spectrometry either prevents HDAC6-mediated activation (K140/409Q) or renders the channels constitutively active (K140R). These data define a non-canonical RhoA-mDia-HDAC6 signaling pathway for GαqPCR activation of PANX1 channels and uncover lysine acetylation-deacetylation as an ion channel silencing-activation mechanism., (© 2021. The Author(s).)

Phagocytes reallocate metabolic resources to kill engulfed pathogens, but the intracellular signals that rapidly switch the immunometabolic program necessary to fuel microbial killing are not understood. We report that macrophages use a fast two-step Ca 2+ relay to meet the bioenergetic demands of phagosomal killing. Upon detection of a fungal pathogen, macrophages rapidly elevate cytosolic Ca 2+ (phase 1), and by concurrently activating the mitochondrial Ca 2+ (mCa 2+ ) uniporter (MCU), they trigger a rapid influx of Ca 2+ into the mitochondria (phase 2). mCa 2+ signaling reprograms mitochondrial metabolism, at least in part, through the activation of pyruvate dehydrogenase (PDH). Deprived of mCa 2+ signaling, Mcu -/- macrophages are deficient in phagosomal reactive oxygen species (ROS) production and defective at killing fungi. Mice lacking MCU in their myeloid cells are highly susceptible to disseminated candidiasis. In essence, this study reveals an elegant design principle that MCU-dependent Ca 2+ signaling is an electrometabolic switch to fuel phagosome killing., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Insulin secretion from β-cells is reduced at the onset of type-1 and during type-2 diabetes. Although inflammation and metabolic dysfunction of β-cells elicit secretory defects associated with type-1 or type-2 diabetes, accompanying changes to insulin granules have not been established. To address this, we performed detailed functional analyses of insulin granules purified from cells subjected to model treatments that mimic type-1 and type-2 diabetic conditions and discovered striking shifts in calcium affinities and fusion characteristics. We show that this behavior is correlated with two subpopulations of insulin granules whose relative abundance is differentially shifted depending on diabetic model condition. The two types of granules have different release characteristics, distinct lipid and protein compositions, and package different secretory contents alongside insulin. This complexity of β-cell secretory physiology establishes a direct link between granule subpopulation and type of diabetes and leads to a revised model of secretory changes in the diabetogenic process., Competing Interests: AK, VK, CD, NS, CU, ME, AW, JP, SH, WT, PS, IK, MH, BL, AK, BD, NL, AA, JC, LT No competing interests declared, (© 2020, Kreutzberger et al.)

Highly selective, positive allosteric modulators (PAMs) of the M 1 subtype of muscarinic acetylcholine receptor have emerged as an exciting new approach to potentially improve cognitive function in patients suffering from Alzheimer's disease and schizophrenia. Discovery programs have produced a structurally diverse range of M 1 receptor PAMs with distinct pharmacological properties, including different extents of agonist activity and differences in signal bias. This includes biased M 1 receptor PAMs that can potentiate coupling of the receptor to activation of phospholipase C (PLC) but not phospholipase D (PLD). However, little is known about the role of PLD in M 1 receptor signaling in native systems, and it is not clear whether biased M 1 PAMs display differences in modulating M 1 -mediated responses in native tissue. Using PLD inhibitors and PLD knockout mice, we showed that PLD was necessary for the induction of M 1 -dependent long-term depression (LTD) in the prefrontal cortex (PFC). Furthermore, biased M 1 PAMs that did not couple to PLD not only failed to potentiate orthosteric agonist-induced LTD but also blocked M 1 -dependent LTD in the PFC. In contrast, biased and nonbiased M 1 PAMs acted similarly in potentiating M 1 -dependent electrophysiological responses that were PLD independent. These findings demonstrate that PLD plays a critical role in the ability of M 1 PAMs to modulate certain central nervous system (CNS) functions and that biased M 1 PAMs function differently in brain regions implicated in cognition., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Highly selective positive allosteric modulators (PAMs) of the M 1 subtype of muscarinic acetylcholine receptor have emerged as an exciting new approach for improving cognitive function in patients suffering from Alzheimer's disease and schizophrenia. However, excessive activation of M 1 is known to induce seizure activity and have actions in the prefrontal cortex (PFC) that could impair cognitive function. We now report a series of pharmacological, electrophysiological, and behavioral studies in which we find that recently reported M 1 PAMs, PF-06764427 and MK-7622, have robust agonist activity in cell lines and agonist effects in the mouse PFC, and have the potential to overactivate the M 1 receptor and disrupt PFC function. In contrast, structurally distinct M 1 PAMs (VU0453595 and VU0550164) are devoid of agonist activity in cell lines and maintain activity dependence of M 1 activation in the PFC. Consistent with the previously reported effect of PF-06764427, the ago-PAM MK-7622 induces severe behavioral convulsions in mice. In contrast, VU0453595 does not induce behavioral convulsions at doses well above those required for maximal efficacy in enhancing cognitive function. Furthermore, in contrast to the robust efficacy of VU0453595, the ago-PAM MK-7622 failed to improve novel object recognition, a rodent assay of cognitive function. These findings suggest that in vivo cognition-enhancing efficacy of M 1 PAMs can be observed with PAMs lacking intrinsic agonist activity and that intrinsic agonist activity of M 1 PAMs may contribute to adverse effects and reduced efficacy in improving cognitive function.

In pancreatic β-cells, insulin granule membranes are enriched in cholesterol and are both recycled and newly generated. Cholesterol's role in supporting granule membrane formation and function is poorly understood. ATP binding cassette transporters ABCG1 and ABCA1 regulate intracellular cholesterol and are important for insulin secretion. RNAi inter-ference-induced depletion in cultured pancreatic β-cells shows that ABCG1 is needed to stabilize newly made insulin granules against lysosomal degradation; ABCA1 is also involved but to a lesser extent. Both transporters are also required for optimum glucose-stimulated insulin secretion, likely via complementary roles. Exogenous cholesterol addition rescues knockdown-induced granule loss (ABCG1) and reduced secretion (both transporters). Another cholesterol transport protein, oxysterol binding protein (OSBP), appears to act proximally as a source of endogenous cholesterol for granule formation. Its knockdown caused similar defective stability of young granules and glucose-stimulated insulin secretion, neither of which were rescued with exogenous cholesterol. Dual knockdowns of OSBP and ABC transporters support their serial function in supplying and concentrating cholesterol for granule formation. OSBP knockdown also decreased proinsulin synthesis consistent with a proximal endoplasmic reticulum defect. Thus, membrane cholesterol distribution contributes to insulin homeostasis at production, packaging, and export levels through the actions of OSBP and ABCs G1 and A1.

The US federal government has enacted legislation for a federal incentive program for health care providers and hospitals to implement electronic health records. The primary goal of the Meaningful Use (MU) program is to drive adoption of electronic health records nationwide and set the stage to monitor and guide efforts to improve population health and outcomes. The MU program provides incentives for the adoption and use of electronic health record technology and, in some cases, penalties for hospitals or providers not using the technology. The MU program is administrated by the Department of Health and Human Services and is divided into 3 stages that include specific reporting and compliance metrics. The rationale is that increased use of electronic health records will improve the process of delivering care at the individual level by improving the communication and allow for tracking population health and quality improvement metrics at a national level in the long run. The goal of this narrative review is to describe the MU program as it applies to anesthesiologists in the United States. This narrative review will discuss how anesthesiologists can meet the eligible provider reporting criteria of MU by applying anesthesia information management systems (AIMS) in various contexts in the United States. Subsequently, AIMS will be described in the context of MU criteria. This narrative literature review also will evaluate the evidence supporting the electronic health record technology in the operating room, including AIMS, independent of certification requirements for the electronic health record technology under MU in the United States.