Biology subjects

Festuccia, W. T.

Publications and source records attributed to Festuccia, W. T..

7 recordsLinked to original sources

bioRxiv2026

Constitutive PI3K-AKT activation promotes steatohepatitis through de novo lipogenesis despite enhanced mitochondrial β-oxidation, essential fatty acid depletion and reduced lipid peroxidation

Background. Activation of de novo lipogenesis (DNL) is a major hallmark of steatotic liver disease (SLD), a highly prevalent group of diseases ranging from a harmless steatosis to more severe steatohepatitis, cirrhosis, and hepatocellular carcinoma. We interrogated herein the early alterations in liver proteome, transcriptome, lipidome, inflammation, fibrosis, and oxidative status in a mouse model of progressive SLD induced by constitutive activation of PI3K-AKT signaling, the major inducer of DNL. Methods. Male, 8 weeks-old mice bearing phosphatase and tensin homolog (Pten) deletion and therefore constitutive activation of PI3K-AKT in hepatocytes (albumin-Cre) and littermate controls were evaluated for liver steatosis, injury, lipid peroxidation, metabolism, proteome, lipidome and transcriptome either upon feeding with a chow or high-fat diets supplemented or not with linoleic acid or after treatment with vehicle or acetyl-CoA carboxylase (ACC) inhibitor (ND-630, 20 mg/kg/day, i.p.) Results. Mice bearing Pten deletion and therefore constitutive activation of PI3K-AKT in hepatocytes display steatohepatitis characterized by enhanced DNL, severe steatosis, hepatocyte ballooning, inflammation, fibrosis and hepatomegaly, which, unexpectedly, was associated with reduced lipid peroxidation, increased GSH content and enhanced rates of triacylglycerol turnover, fatty acid {beta}-oxidation, tricarboxylic acid cycle flux, and mitochondrial respiration, altogether promoting a robust lipidome remodeling mainly defined by enrichment of DNL-derived fatty acids in detriment of a broad depletion of essential fatty acids (linoleic and -linolenic acids) and cardiolipins. Dietary restoration of liver linoleic acid content mildly attenuated liver inflammation, without however affecting lipid peroxidation and improving steatosis and fibrosis, whereas pharmacological acetyl-CoA carboxylase (ACC) and DNL inhibition markedly reduced steatosis, inflammation and fibrosis, despite further lowering hepatic linoleic acid content. Conclusions. Collectively, these findings support a harmful role of essential fatty acids depletion fomenting liver inflammation and identify DNL as a major culprit of steatohepatitis induced by constitutive PI3K-AKT activation.

biochemistry↗

bioRxiv2026

Severely lipoatrophic mice are hypermetabolic and hyperthermic under thermoneutral conditions in part due to an enhanced liver de novo lipogenesis

White, beige and brown adipocytes store energy as lipids, secrete hormones and produce heat, playing an important role in the regulation of energy balance through not completely defined mechanisms. We investigate herein the impact of the almost complete absence of mature adipocytes (severe lipoatrophy) in the determination of energy balance (energy intake and expenditure) and homeothermy in mice. For this, mice with severe lipoatrophy induced by adipocyte deletion of peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) (PPAR{gamma} flox adiponectin-Cre) and littermate controls (PPAR{gamma} flox) were evaluated for energy balance, thermoneutral zone, core body temperature, locomotor activity, and gene expression profiles at different ambient temperatures. Severely lipoatrophic mice are heavier, hypermetabolic and hyperphagic and feature a widened thermoneutral zone, lower ambulatory activity, and metabolic inflexibility at both 23 and 17{degrees}C, along with unstable thermal behavior characterized by hyperthermia at 30{degrees}C, normothermia at 23{degrees}C, and bouts of hypothermia at 17{degrees}C. Noteworthy, lipoatrophic mice hypermetabolism at 30{degrees}C is not due to thyroid hormones, impaired insulation or increased body and lean masses and is not altered by pharmacological blockade of either {beta}-adrenergic receptor signaling with propranolol or skeletal muscle sarcoplasmic/endoplasmic reticulum Ca2+-ATPases (SERCA) and sarcolipin (SLN)-mediated calcium cycling with dantrolene, but is partially attenuated by pharmacological inhibition of acetyl-CoA carboxylase (ACC) and de novo lipogenesis with ND-630. In conclusion, severe lipoatrophy causes hypermetabolism and hyperthermia at 30{degrees}C partly through the activation of liver de novo fatty acid synthesis.

physiology↗

bioRxiv2026

Hepatocyte-, but not myeloid cell-Rictor/mTORC2 deficiency moderately attenuates steatotic liver disease induced by intake of a choline-deficient, amino acid-defined high-fat diet

Previous studies have demonstrated that mechanistic target of rapamycin complex 2 (mTORC2) deficiency provides complete protection against steatotic liver disease driven by constitutive activation of the phosphoinositide 3-kinase (PI3K)-Akt signaling pathway and de novo lipogenesis, and partial protection against disease induced by a high-fat diet. We investigated herein whether mTORC2 deficiency in hepatocytes and myeloid cells, including Kupffer cells and recruited macrophages, influences the development of liver disease induced by intake of a choline-deficient, amino acid-defined high-fat diet (CDAHFD), a model in which liver disease is induced by impaired hepatic secretion of very low-density lipoprotein (VLDL) triacylglycerol. For this, mice with either hepatocyte- or myeloid cells-specific deletion of mTORC2 essential component rapamycin-insensitive companion of mTOR (Rictor) and their respective littermate controls were fed with either chow or CDAHFD for 10 weeks and evaluated for hepatic steatosis, inflammation and fibrosis. Our main findings indicate that hepatocyte Rictor/mTORC2 deficiency slightly attenuated the CDAHFD-induced increases in liver mass, macrovesicular steatosis and triacylglycerol accumulation, without affecting though liver cholesterol, serum markers of liver injury (AST and ALT), as well as the upregulation in proinflammatory cytokine IL-1{beta} and expression of fibrosis-related genes. Myeloid cells-Rictor deletion had no detectable impact on liver steatosis, inflammatory, or fibrosis induced by CDAHFD. In conclusion, mTORC2 deficiency show modest beneficial effects in counteracting liver disease induced by CDAHFD intake.

biochemistry↗

bioRxiv2025

Non-invasive and unbiased assessment of thermogenesis in mice through thermal gradient ring

Accurately assessing whole-body heat production requires reliable thermometry methods. In mice, common approaches include rectal temperature (RT) measurement, infrared (IR) thermography, and implanted probes. However, factors such as stress, handling, surgery, and variability limit their applicability for evaluating thermogenesis. The Thermal Gradient Ring (TGR), widely used in neuropathic pain and ion channel studies, consists of a circular structure with twelve temperature zones and an integrated IR camera for real-time behavior monitoring. This system allows precise analysis of preferred temperature (PT), heat tolerance, locomotion, and zone occupancy over time, thereby offering a behavioral perspective beyond traditional thermometric methods, which provides only temperature data. In this study, we evaluated TGR as a non-invasive tool for detecting thermogenic changes. Since mice with higher thermogenesis prefer cooler zones, while those with reduced thermogenesis seek warmth, TGR provides a sensitive readout of metabolic behavior. Using models with both enhanced and impaired thermogenesis, we demonstrated TGRs ability to detect thermogenic status under different conditions. These findings suggest that TGR is a valuable tool for metabolic research, offering a reliable alternative for assessing thermogenesis in mice.

physiology↗

bioRxiv2025

Mitochondrial ATP-Sensitive K+ Channels (MitoKATP) Regulate Brown Adipocyte Differentiation and Metabolism

Brown adipose tissue (BAT) plays a central role in mammalian non-shivering thermogenesis, dissipating mitochondrial membrane potentials through the activity of uncoupling protein UCP1 to release heat. Inner membranes of mitochondria are known to be permeable to potassium ions (K+), which enter the matrix either through ATP-sensitive channels (MitoKATP) or leakage across the bilayer driven by inner membrane potentials. Mitochondrial K+ influx is associated with increased osmotic pressure, promoting water influx and increasing matrix volume. Since BAT mitochondria have lower inner membrane potentials due to uncoupling protein 1 (UCP1) activity, we hypothesized this could involve compensatory changes in MitoKATP activity, and thus tested MitoKATP involvement in brown adipocyte activities under basal and stimulated conditions. We find that cold exposure and adrenergic stimulation in mice modulate BAT MitoK levels, the channel portion of MitoKATP. Genetic ablation of the gene that codes for the pore-forming subunit of MitoKATP in human pre-adipocytes decreased cellular respiration and proliferation, compromising differentiation into mature adipocytes. In mouse cell lines, the absence of the protein limited cellular oxygen consumption in the precursor stage, but not in mature adipocytes. Interestingly, inhibition of MitoKATP in mature adipocytes increased adrenergic-stimulated oxygen consumption, indicating that shutdown of this pathway is important for full BAT thermogenesis. Similarly, MitoKATP inhibition increased oxygen consumption in BAT mitochondria isolated from mice treated with beta 3 adrenergic receptor agonist CL316,243. Overall, our results suggest that the activity of MitoKATP regulates differentiation and metabolism of brown adipocytes, impacting on thermogenesis. New and NoteworthyBrown fat cells are important to maintain healthy body weight by promoting mitochondrial uncoupling. Here, we demonstrate that mitochondrial ATP-sensitive potassium channels (MitoKATP) have important roles both in the differentiation of brown fat cells and in the activation of energy-dissipating uncoupling in this tissue.

physiology↗

bioRxiv2023

Plasma Oxylipin Profiling by High Resolution Mass Spectrometry Reveal Signatures of Inflammation and Hypermetabolism in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized not only by progressive loss of motor neurons, but also linked to systemic hypermetabolism, oxidative stress, and inflammation. In this context, oxylipins have been investigated as signaling molecules linked to neurodegeneration. However, the nature and role of major oxylipins involved in ALS disease progression remain unclear. Importantly, most methods focused on oxylipin analysis are based on low resolution mass spectrometry (LRMS), which usually confers high sensitivity, but not great accuracy for lipid identification, as provided by high-resolution MS (HRMS). Here, we established an ultra-high performance liquid chromatography coupled HRMS (LC-HRMS) method for simultaneous analysis of 126 oxylipins in plasma, including lipid hydroxides, ketones, epoxides, prostaglandins, leukotrienes, and others in a 15-minute run. Intra- and inter-day method validation showed high sensitivity (0.3 - 25 pg), accuracy and precision for more than 90 % of quality controls. This method was applied for the analysis of oxylipins in plasma of ALS rats overexpressing the mutant human Cu/Zn-superoxide dismutase gene (SOD1-G93A) at asymptomatic (ALS 70 days old) and symptomatic stages (ALS 120 days old), and their respective age-matched wild type controls (WT 70 days old and WT 120 days old). From the 56 oxylipins identified in plasma, 17 species were significantly altered. Remarkably, most of oxylipins linked to inflammation and oxidative stress derived from arachidonic acid, such as, prostaglandins, lipoxins, mono-hydroxides, and isoprostane, were increased in ALS 120d rats. In contrast, the linoleic acid diols involved in fatty acid uptake and {beta}-oxidation, 9(10)-DiHOME and 12(13)-DiHOME, were strongly decreased in the ALS 120d. In summary, we developed and validated a high-throughput LC-HRMS method for oxylipin analysis and provided a comprehensive overview of plasma oxylipins involved in ALS disease progression. Noteworthy, the oxylipins altered in plasma of ALS 120d rats have potential to be investigated and used as biomarkers for inflammation and hypermetabolism in ALS. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/547101v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@937099org.highwire.dtl.DTLVardef@1c5847forg.highwire.dtl.DTLVardef@7dd09borg.highwire.dtl.DTLVardef@a9f8d_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2019

Depletion of Ric-8B leads to reduced mTORC2 activity

mTOR, a serine/threonine protein kinase that is involved in a series of critical cellular processes, can be found in two functionally distinct complexes, mTORC1 and mTORC2. In contrast to mTORC1, little is known about the mechanisms that regulate mTORC2. Here we show that mTORC2 activity is reduced in mice with a hypomorphic mutation of the Ric-8B gene. Ric-8B is a highly conserved protein that acts as a non-canonical guanine nucleotide exchange factor (GEF) for heterotrimeric Gs/olf type subunits. We found that Ric-8B hypomorph embryos are smaller than their wild type littermates, fail to close the neural tube in the cephalic region and die during mid-embryogenesis. Comparative transcriptome analysis revealed that signaling pathways involving GPCRs and G proteins are dysregulated in the Ric-8B mutant embryos. Interestingly, this analysis also revealed an unexpected impairment of the mTOR signaling pathway.\n\nPhosphorylation of Akt at Ser 473 is downregulated in the Ric-8B mutant embryos, indicating a decreased activity of mTORC2. In contrast, phosphorylation of S6, a downstream target of mTORC1, is unaltered. Knockdown of the endogenous Ric-8B gene in HEK293T cells leads to reduced phosphorylation levels of Akt at Ser 473, but not of S6, further supporting the selective involvement of Ric-8B in mTORC2 activity. Our results reveal a crucial role for Ric-8B in development and provide novel insights into the signals that regulate mTORC2 activity.\n\nAuthor SummaryGene inactivation in mice can be used to identify genes that are involved in important biological processes and that may contribute to disease. By using this approach, we found that the Ric-8B gene is essential for embryogenesis and for the normal development of the nervous system. Ric-8B mutant mouse embryos are smaller than their wild type littermates and show neural tube defects at the cranial region. This approach also allowed us to identify the biological pathways that are involved in the observed phenotypes, the G protein and mTORC2 signaling pathways. mTORC2 plays particular important roles also in the adult brain, and has been implicated in neurological disorders. Ric-8B is highly conserved in mammals, including humans. Our mutant mice provide a model to study the complex molecular and cellular processes underlying the interplay between Ric-8B and mTORC2 in neuronal function.

molecular biology↗