Multi-species genome-wide CRISPR screens identify conserved suppressors of cold-induced cell death.

Cells must adapt to environmental changes to maintain homeostasis. One of the most striking environmental adaptations is entry into hibernation during which core body temperature can decrease from 37°C to as low at 4°C. How mammalian cells, which evolved to optimally function within a narrow range of temperatures, adapt to this profound decrease in temperature remains poorly understood. In this study, we conducted the first genome-scale CRISPR-Cas9 screen in cells derived from Syrian hamster, a facultative hibernator, as well as human cells to investigate the genetic basis of cold tolerance in a hibernator and a non-hibernator in an unbiased manner. Both screens independently revealed glutathione peroxidase 4 (GPX4), a selenium-containing enzyme, and associated proteins as critical for cold tolerance. We utilized genetic and pharmacological approaches to demonstrate that GPX4 is active in the cold and its catalytic activity is required for cold tolerance. Furthermore, we show that the role of GPX4 as a suppressor of cold-induced cell death extends across hibernating species, including 13-lined ground squirrels and greater horseshoe bats, highlighting the evolutionary conservation of this mechanism of cold tolerance. This study identifies GPX4 as a central modulator of mammalian cold tolerance and advances our understanding of the evolved mechanisms by which cells mitigate cold-associated damage-one of the most common challenges faced by cells and organisms in nature.

The effect of a selenium-based anti-inflammatory strategy on postoperative functional recovery in high-risk cardiac surgery patients - A nested sub-study of the sustain CSX trial.

AIM: The cardiac surgery-related ischemia-reperfusion-related oxidative stress triggers the release of cytotoxic reactive oxygen and nitrogen species, contributing to organ failure and ultimately influencing patients' short- and long-term outcomes. Selenium is an essential co-factor for various antioxidant enzymes, thereby contributing to the patients' endogenous antioxidant and anti-inflammatory defense mechanisms. Given these selenium's pleiotropic functions, we investigated the effect of a high-dose selenium-based anti-inflammatory perioperative strategy on functional recovery after cardiac surgery. MATERIALS AND METHODS: This prospective study constituted a nested sub-study of the SUSTAIN CSX trial, a double-blinded, randomized, placebo-controlled multicenter trial to investigate the impact of high-dose selenium supplementation on high-risk cardiac surgery patients' postoperative recovery. Functional recovery was assessed by 6-min walk distance, Short Form-36 (SF-36) and Barthel Index questionnaires. KEY FINDINGS: 174 patients were included in this sub-study. The mean age (SD) was 67.3 (8.9) years, and 78.7 % of the patients were male. The mean (SD) predicted 30-day mortality by the European System for Cardiac Operative Risk Evaluation II score was 12.6 % (9.4 %). There was no difference at hospital discharge and after three months in the 6-min walk distance between the selenium and placebo groups (131 m [IQR: not performed - 269] vs. 160 m [IQR: not performed - 252], p = 0.80 and 400 m [IQR: 299-461] vs. 375 m [IQR: 65-441], p = 0.48). The SF-36 and Barthel Index assessments also revealed no clinically meaningful differences between the selenium and placebo groups. SIGNIFICANCE: A perioperative anti-inflammatory strategy with high-dose selenium supplementation did not improve functional recovery in high-risk cardiac surgery patients.

A torpor-like state (TLS) in mice slows blood epigenetic aging and prolongs healthspan.

Torpor and hibernation are extreme physiological adaptations of homeotherms associated with pro-longevity effects. Yet the underlying mechanisms of how torpor affects aging, and whether hypothermic and hypometabolic states can be induced to slow aging and increase health span, remain unknown. We demonstrate that the activity of a spatially defined neuronal population in the avMLPA, which has previously been identified as a torpor-regulating brain region, is sufficient to induce a torpor like state (TLS) in mice. Prolonged induction of TLS slows epigenetic aging across multiple tissues and improves health span. We isolate the effects of decreased metabolic rate, long-term caloric restriction, and decreased core body temperature (Tb) on blood epigenetic aging and find that the pro-longevity effect of torpor-like states is mediated by decreased Tb. Taken together, our findings provide novel mechanistic insight into the pro-longevity effects of torpor and hibernation and support the growing body of evidence that Tb is an important mediator of aging processes.

Long ant life span is maintained by a unique heat shock factor.

Eusocial insect reproductive females show strikingly longer life spans than nonreproductive female workers despite high genetic similarity. In the ant Harpegnathos saltator (Hsal), workers can transition to reproductive "gamergates," acquiring a fivefold prolonged life span by mechanisms that are poorly understood. We found that gamergates have elevated expression of heat shock response (HSR) genes in the absence of heat stress and enhanced survival with heat stress. This HSR gene elevation is driven in part by gamergate-specific up-regulation of the gene encoding a truncated form of a heat shock factor most similar to mammalian HSF2 (hsalHSF2). In workers, hsalHSF2 was bound to DNA only upon heat stress. In gamergates, hsalHSF2 bound to DNA even in the absence of heat stress and was localized to gamergate-biased HSR genes. Expression of hsalHSF2 in Drosophila melanogaster led to enhanced heat shock survival and extended life span in the absence of heat stress. Molecular characterization illuminated multiple parallels between long-lived flies and gamergates, underscoring the centrality of hsalHSF2 to extended ant life span. Hence, ant caste-specific heat stress resilience and extended longevity can be transferred to flies via hsalHSF2. These findings reinforce the critical role of proteostasis in health and aging and reveal novel mechanisms underlying facultative life span extension in ants.

Association between body mass index and difficult intubation with a double lumen tube: A retrospective cohort study.

STUDY OBJECTIVE: Obesity, defined by the World Health Organization as body mass index (BMI) ≥ 30.0 kg/m2, is associated with adverse outcomes and challenges during surgery. Difficulties during endotracheal intubation, occur in 3-8% of procedures and are among the principal causes of anesthetic-related morbidity and mortality. Endotracheal intubation can be challenging in obese patients due to an array of anatomic and physiologic factors. Double lumen tubes (DLTs), the most commonly used airway technique to facilitate anatomic isolation of the lungs for one lung ventilation. However, DLTs can be difficult to properly position and are also more likely to cause airway injuries and bleeding when compared to conventional single lumen tubes. We investigated the association between BMI and difficult tracheal DLT intubation. DESIGN: Retrospective cohort study. SETTING: Operating room. PATIENTS: We analyzed electronic records of adults having cardiac and thoracic surgery requiring general anesthesia and endotracheal intubation with DLT at the Cleveland Clinic between 2008 and 2021. MEASUREMENTS: BMI, preoperative airway abnormalities and difficult intubation, defined as more than one intubation attempt, was assessed using multivariable logistic regression. MAIN RESULTS: Among 8641 analyzed anesthetics requiring DLT, 1459 (17%) were difficult intubations. After adjusting for confounders, each 5 kg/m2 increase in BMI was associated with a marginal increase of difficult intubation, odds ratio (OR) 1.06 (95% Confidence Interval [CI]: 1.002, 1.11; P = 0.040). Difficult intubation was not associated with airway abnormalities, estimated OR 0.85 (95% CI: 0.62, 1.17; P = 0.321). There was no interaction between known airway abnormalities and BMI (P = 0.894). CONCLUSIONS: Difficult intubations with DLT remain common, but BMI is a weak predictor thereof. For example, an increase in BMI from 20 to 40 kg/m2 corresponds to an increase in average absolute risk for difficult intubation from 16 to 19%, which probably is not clinically meaningful.

Fumarate is a terminal electron acceptor in the mammalian electron transport chain.

For electrons to continuously enter and flow through the mitochondrial electron transport chain (ETC), they must ultimately land on a terminal electron acceptor (TEA), which is known to be oxygen in mammals. Paradoxically, we find that complex I and dihydroorotate dehydrogenase (DHODH) can still deposit electrons into the ETC when oxygen reduction is impeded. Cells lacking oxygen reduction accumulate ubiquinol, driving the succinate dehydrogenase (SDH) complex in reverse to enable electron deposition onto fumarate. Upon inhibition of oxygen reduction, fumarate reduction sustains DHODH and complex I activities. Mouse tissues display varying capacities to use fumarate as a TEA, most of which net reverse the SDH complex under hypoxia. Thus, we delineate a circuit of electron flow in the mammalian ETC that maintains mitochondrial functions under oxygen limitation.

Epigenetic Regulator CoREST Controls Social Behavior in Ants.

Ants acquire distinct morphological and behavioral phenotypes arising from a common genome, underscoring the importance of epigenetic regulation. In Camponotus floridanus, "Major" workers defend the colony, but can be epigenetically reprogrammed to forage for food analogously to "Minor" workers. Here, we utilize reprogramming to investigate natural behavioral specification. Reprogramming of Majors upregulates Minor-biased genes and downregulates Major-biased genes, engaging molecular pathways fundamental to foraging behavior. We discover the neuronal corepressor for element-1-silencing transcription factor (CoREST) is upregulated upon reprogramming and required for the epigenetic switch to foraging. Genome-wide profiling during reprogramming reveals CoREST represses expression of enzymes that degrade juvenile hormone (JH), a hormone elevated upon reprogramming. High CoREST, low JH-degrader expression, and high JH levels are mirrored in natural Minors, revealing parallel mechanisms of natural and reprogrammed foraging. These results unveil chromatin regulation via CoREST as central to programming of ant social behavior, with potential far-reaching implications for behavioral epigenetics.