A Platform for Mitochondrial Profiling in Enriched Kidney Segments Under Thermodynamic Control.

Mitochondrial function varies widely across kidney nephron segments, yet conventional approaches lack the resolution and control needed to assess cell-type-specific bioenergetics in situ. We present a methodological platform that enables segment-resolved profiling of mitochondrial respiration, conductance, and membrane potential in freshly isolated mouse nephron segments. Combining mechanical sieving and adhesion-based enrichment with permeabilized high-resolution respirometry, we adapted the creatine kinase clamp to quantify oxygen flux and mitochondrial membrane potential across defined free energies.

Acid ceramidase inhibition enhances BCL-2 targeting in venetoclax-resistant acute myeloid leukemia via a cytotoxic integrated stress response.

Resistance to combination regimens containing the BCL-2 inhibitor venetoclax in acute myeloid leukemia (AML) is a growing clinical challenge for this extensively utilized agent. We previously established the anti-leukemic properties of ceramide, a tumor-suppressive sphingolipid, in AML and demonstrated that upregulated expression of acid ceramidase (AC), a ceramide-neutralizing enzyme, supported leukemic survival and resistance to BH3 mimetics. Here, we report the anti-leukemic efficacy and mechanisms of co-targeting AC and BCL-2 in venetoclax-resistant AML.

microRNA-1 regulates metabolic flexibility by programming adult skeletal muscle pyruvate metabolism.

Objective: Metabolic flexibility refers to the ability of tissues to adjust cellular fuel choice in response to conditional changes in metabolic demand and activity. A loss of metabolic flexibility is a defining feature of various diseases and cellular dysfunction. This study investigated the role of microRNA-1 (miR-1), the most abundant microRNA in skeletal muscle, in maintaining whole-body metabolic flexibility.

Acute mitochondrial reactive oxygen species emissions drive mitochondrial dysfunction after traumatic muscle injury in male mice.

Volumetric muscle loss (VML) is characterized by contractile weakness, dysfunctional mitochondrial bioenergetics, and poor rehabilitation plasticity. A hyperpolarized mitochondrial membrane potential is one attribute of the dysfunction bioenergetics and can lead to excessive reactive oxygen species (ROS) emissions. The primary objective of this study was to define the role of acute ROS emissions after VML injury.

Impact of physiological media on acute myeloid leukemia bioenergetics and cell proliferation.

Increasing emphasis has been placed on improving the physiological relevance of cell culture media with formulations such as Human Plasma-Like Medium (HPLM). Given that shifts in mitochondrial metabolism and nutrient use are emerging as anti-cancer targets, the present study sought to investigate the impact of culture media formulation on mitochondrial bioenergetics and cancer cell growth. To do this, we used acute myeloid leukemia (AML) cells and compared acute and chronic effects of HPLM versus different supraphysiological medias.

Semaglutide-induced weight loss improves mitochondrial energy efficiency in skeletal muscle.

Objective: Glucagon-like peptide-1 receptor agonists (e.g., semaglutide) potently induce weight loss, thereby reducing obesity-related complications.

Elevated mitochondrial membrane potential is a therapeutic vulnerability in Dnmt3a-mutant clonal hematopoiesis.

The competitive advantage of mutant hematopoietic stem and progenitor cells (HSPCs) underlies clonal hematopoiesis (CH). Drivers of CH include aging and inflammation; however, how CH-mutant cells gain a selective advantage in these contexts is an unresolved question. Using a murine model of CH (Dnmt3a), we discover that mutant HSPCs sustain elevated mitochondrial respiration which is associated with their resistance to aging-related changes in the bone marrow microenvironment.

Acute myeloid leukemia mitochondria hydrolyze ATP to support oxidative metabolism and resist chemotherapy.

OxPhos inhibitors have struggled to show a clinical benefit because of their inability to distinguish healthy from cancerous mitochondria. Herein, we describe an actionable bioenergetic mechanism unique to acute myeloid leukemia (AML) mitochondria. Unlike healthy cells that couple respiration to ATP synthesis, AML mitochondria support inner-membrane polarization by consuming ATP.

Effect of in utero metformin exposure in gestational diabetes mellitus on infant mesenchymal stem cell metabolism.

Offspring exposed to metformin treatment for gestational diabetes mellitus (GDM) experience altered growth patterns that increase the risk for developing cardiometabolic diseases later in life. The adaptive cellular mechanisms underlying these patterns remain unclear. Therefore, the objective of this study was to determine whether chronic in utero metformin exposure associated with GDM treatment elicits infant cellular metabolic adaptations.

Cardiolipin deficiency disrupts electron transport chain to drive steatohepatitis.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive disorder marked by lipid accumulation, leading to metabolic dysfunction-associated steatohepatitis (MASH). A key feature of the transition to MASH involves oxidative stress resulting from defects in mitochondrial oxidative phosphorylation (OXPHOS). Here, we show that pathological alterations in the lipid composition of the inner mitochondrial membrane (IMM) directly instigate electron transfer inefficiency to promote oxidative stress.

Author Correction: Limited oxygen in standard cell culture alters metabolism and function of differentiated cells.

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microRNA-1 Regulates Metabolic Flexibility in Skeletal Muscle via Pyruvate Metabolism.

MicroRNA-1 (miR-1) is the most abundant miRNA in adult skeletal muscle. To determine the function of miR-1 in adult skeletal muscle, we generated an inducible, skeletal muscle-specific miR-1 knockout (KO) mouse. Integration of RNA-sequencing (RNA-seq) data from miR-1 KO muscle with Argonaute 2 enhanced crosslinking and immunoprecipitation sequencing (AGO2 eCLIP-seq) from human skeletal muscle identified miR-1 target genes involved with glycolysis and pyruvate metabolism.

Acute myeloid leukemia mitochondria hydrolyze ATP to resist chemotherapy.

Despite early optimism, therapeutics targeting oxidative phosphorylation (OxPhos) have faced clinical setbacks, stemming from their inability to distinguish healthy from cancerous mitochondria. Herein, we describe an actionable bioenergetic mechanism unique to cancerous mitochondria inside acute myeloid leukemia (AML) cells. Unlike healthy cells which couple respiration to the synthesis of ATP, AML mitochondria were discovered to support inner membrane polarization by consuming ATP.

Limited oxygen in standard cell culture alters metabolism and function of differentiated cells.

The in vitro oxygen microenvironment profoundly affects the capacity of cell cultures to model physiological and pathophysiological states. Cell culture is often considered to be hyperoxic, but pericellular oxygen levels, which are affected by oxygen diffusivity and consumption, are rarely reported. Here, we provide evidence that several cell types in culture actually experience local hypoxia, with important implications for cell metabolism and function.

High Fat Diet-Induced Obesity Dysregulates Splenic B Cell Mitochondrial Activity.

Diet-induced obesity impairs mitochondrial respiratory responses in tissues that are highly metabolically active, such as the heart. However, less is known about the impact of obesity on the respiratory activity of specific cell types, such as splenic B cells. B cells are of relevance, as they play functional roles in obesity-induced insulin resistance, inflammation, and responses to infection.

Pan-tissue mitochondrial phenotyping reveals lower OXPHOS expression and function across cancer types.

Targeting mitochondrial oxidative phosphorylation (OXPHOS) to treat cancer has been hampered due to serious side-effects potentially arising from the inability to discriminate between non-cancerous and cancerous mitochondria. Herein, comprehensive mitochondrial phenotyping was leveraged to define both the composition and function of OXPHOS across various murine cancers and compared to both matched normal tissues and other organs. When compared to both matched normal tissues, as well as high OXPHOS reliant organs like heart, intrinsic expression of the OXPHOS complexes, as well as OXPHOS flux were discovered to be consistently lower across distinct cancer types.

Weight loss increases skeletal muscle mitochondrial energy efficiency in obese mice.

Weight loss from an overweight state is associated with a disproportionate decrease in whole-body energy expenditure that may contribute to the heightened risk for weight regain. Evidence suggests that this energetic mismatch originates from lean tissue. Although this phenomenon is well documented, the mechanisms have remained elusive.

Hypoxia Resistance Is an Inherent Phenotype of the Mouse Flexor Digitorum Brevis Skeletal Muscle.

The various functions of skeletal muscle (movement, respiration, thermogenesis, etc.) require the presence of oxygen (O). Inadequate O bioavailability (ie, hypoxia) is detrimental to muscle function and, in chronic cases, can result in muscle wasting.

Simultaneous Inhibition of Ceramide Hydrolysis and Glycosylation Synergizes to Corrupt Mitochondrial Respiration and Signal Caspase Driven Cell Death in Drug-Resistant Acute Myeloid Leukemia.

Acute myelogenous leukemia (AML), the most prevalent acute and aggressive leukemia diagnosed in adults, often recurs as a difficult-to-treat, chemotherapy-resistant disease. Because chemotherapy resistance is a major obstacle to successful treatment, novel therapeutic intervention is needed. Upregulated ceramide clearance via accelerated hydrolysis and glycosylation has been shown to be an element in chemotherapy-resistant AML, a problem considering the crucial role ceramide plays in eliciting apoptosis.

Mitochondrial phosphatidylethanolamine modulates UCP1 to promote brown adipose thermogenesis.

Thermogenesis by uncoupling protein 1 (UCP1) is one of the primary mechanisms by which brown adipose tissue (BAT) increases energy expenditure. UCP1 resides in the inner mitochondrial membrane (IMM), where it dissipates membrane potential independent of adenosine triphosphate (ATP) synthase. Here, we provide evidence that phosphatidylethanolamine (PE) modulates UCP1-dependent proton conductance across the IMM to modulate thermogenesis.

The prohibitin complex regulates macrophage fatty acid composition, plasma membrane packing, and lipid raft-mediated inflammatory signaling.

Prohibitins (PHB1 and PHB2) are ubiquitously expressed proteins which play critical roles in multiple biological processes, and together form the ring-like PHB complex found in phospholipid-rich cellular compartments including lipid rafts. Recent studies have implicated PHB1 as a mediator of fatty acid transport as well as a membrane scaffold mediating B lymphocyte and mast cell signal transduction. However, the specific role of PHBs in the macrophage have not been characterized, including their role in fatty acid uptake and lipid raft-mediated inflammatory signaling.

Calcium signaling induced by 15-deoxy-prostamide-J2 promotes cell death by activating PERK, IP3R, and the mitochondrial permeability transition pore.

Melanoma is the deadliest form of skin cancer in the US. Although immunotherapeutic checkpoint inhibitors and small-molecule kinase inhibitors have dramatically increased the survival of patients with melanoma, new or optimized therapeutic approaches are still needed to improve outcomes. 15-deoxy-Δ-prostamide J (15d-PMJ) is an investigational small-molecule that induces ER stress-mediated apoptosis selectively in tumor cells.

Intrinsic adaptations in OXPHOS power output and reduced tumorigenicity characterize doxorubicin resistant ovarian cancer cells.

Although the development of chemoresistance is multifactorial, active chemotherapeutic efflux driven by upregulations in ATP binding cassette (ABC) transporters are commonplace. Chemotherapeutic efflux pumps, like ABCB1, couple drug efflux to ATP hydrolysis and thus potentially elevate cellular demand for ATP resynthesis. Elevations in both mitochondrial content and cellular respiration are common phenotypes accompanying many models of cancer cell chemoresistance, including those dependent on ABCB1.