β-Adrenergic agonist and antagonist regulation of autophagy in HepG2 cells, primary mouse hepatocytes, and mouse liver

G protein-coupled receptor-mediated autophagy in health and disease

G protein-coupled receptors (GPCRs) constitute the largest and most diverse superfamily of mammalian transmembrane proteins. These receptors are involved in a wide range of physiological functions and are targets for more than a third of available drugs in the market. Autophagy is a cellular process involved in degrading damaged proteins and organelles and in recycling cellular components. Deficiencies in autophagy are involved in a variety of pathological conditions. Both GPCRs and autophagy are essential in preserving homeostasis and cell survival. There is emerging evidence suggesting that GPCRs are direct regulators of autophagy. Additionally, autophagic machinery is involved in the regulation of GPCR signalling. The interplay between GPCR and autophagic signalling mechanisms significantly impacts on health and disease; however, there is still an incomplete understanding of the underlying mechanisms and therapeutic implications in different tissues and disease contexts. This review aims to discuss the interactions between GPCR and autophagy signalling. Studies on muscarinic receptors, beta-adrenoceptors, taste receptors, purinergic receptors and adhesion GPCRs are summarized, in relation to autophagy.

Hallmarks of cardiovascular ageing

Normal circulatory function is a key determinant of disease-free life expectancy (healthspan). Indeed, pathologies affecting the cardiovascular system, which are growing in prevalence, are the leading cause of global morbidity, disability and mortality, whereas the maintenance of cardiovascular health is necessary to promote both organismal healthspan and lifespan. Therefore, cardiovascular ageing might precede or even underlie body-wide, age-related health deterioration. In this Review, we posit that eight molecular hallmarks are common denominators in cardiovascular ageing, namely disabled macroautophagy, loss of proteostasis, genomic instability (in particular, clonal haematopoiesis of indeterminate potential), epigenetic alterations, mitochondrial dysfunction, cell senescence, dysregulated neurohormonal signalling and inflammation. We also propose a hierarchical order that distinguishes primary (upstream) from antagonistic and integrative (downstream) hallmarks of cardiovascular ageing. Finally, we discuss how targeting each of the eight hallmarks might be therapeutically exploited to attenuate residual cardiovascular risk in older individuals.

Lithium engages autophagy for neuroprotection and neuroplasticity: translational evidence for therapy

Here an overview is provided on therapeutic/neuroprotective effects of Lithium (Li⁺) in neurodegenerative and psychiatric disorders focusing on the conspicuous action of Li⁺ through autophagy. The effects on the autophagy machinery remain the key molecular mechanisms to explain the protective effects of Li⁺ for neurodegenerative diseases, offering potential therapeutic strategies for the treatment of neuropsychiatric disorders and emphasizes a crossroad linking autophagy, neurodegenerative disorders, and mood stabilization. Sensitization by psychostimulants points to several mechanisms involved in psychopathology, most also crucial in neurodegenerative disorders. Evidence shows the involvement of autophagy and metabotropic Glutamate receptors-5 (mGluR5) in neurodegeneration due to methamphetamine neurotoxicity as well as in neuroprotection, both in vitro and in vivo models. More recently, Li⁺ was shown to modulate autophagy through its action on mGluR5, thus pointing to an additional way of autophagy engagement by Li⁺ and to a substantial role of mGluR5 in neuroprotection related to neural e neuropsychiatry diseases. We propose Li⁺ engagement of autophagy through the canonical mechanisms of autophagy machinery and through the intermediary of mGluR5.

Autophagy: A Cellular Guardian against Hepatic Lipotoxicity

Lipotoxicity is a phenomenon of lipid-induced cellular injury in nonadipose tissue. Excess of free saturated fatty acids (SFAs) contributes to hepatic injury in nonalcoholic fatty liver disease (NAFLD), which has been growing at an unprecedented rate in recent years. SFAs and their derivatives such as ceramides and membrane phospholipids have been shown to induce intrahepatic oxidative damage and ER stress. Autophagy represents a cellular housekeeping mechanism to counter the perturbation in organelle function and activation of stress signals within the cell. Several aspects of autophagy, including lipid droplet assembly, lipophagy, mitophagy, redox signaling and ER-phagy, play a critical role in mounting a strong defense against lipotoxic lipid species within the hepatic cells. This review provides a succinct overview of our current understanding of autophagy-lipotoxicity interaction and its pharmacological and nonpharmacological modulation in treating NAFLD.

Targeting the β2 -adrenergic receptor increases chemosensitivity in multiple myeloma by induction of apoptosis and modulating cancer cell metabolism

While multi-drug combinations and continuous treatment have become standard for multiple myeloma, the disease remains incurable. Repurposing drugs that are currently used for other indications could provide a novel approach to improve the therapeutic efficacy of standard multiple myeloma treatments. Here, we assessed the anti-tumor effects of cardiac drugs called β-blockers as a single agent and in combination with commonly used anti-myeloma therapies. Expression of the β2 -adrenergic receptor correlated with poor survival outcomes in patients with multiple myeloma. Targeting the β2 -adrenergic receptor (β2 AR) using either selective or non-selective β-blockers reduced multiple myeloma cell viability, and induced apoptosis and autophagy. Blockade of the β2 AR modulated cancer cell metabolism by reducing the mitochondrial respiration as well as the glycolytic activity. These effects were not observed by blockade of β1 -adrenergic receptors. Combining β2 AR blockade with the chemotherapy drug melphalan or the proteasome inhibitor bortezomib significantly increased apoptosis in multiple myeloma cells. These data identify the therapeutic potential of β2 AR-blockers as a complementary or additive approach in multiple myeloma treatment and support the future clinical evaluation of non-selective β-blockers in a randomized controlled trial. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Role of AMPK-SREBP Signaling in Regulating Fatty Acid Binding-4 (FABP4) Expression following Ethanol Metabolism

Fatty acid binding protein-4 (FABP4) is not normally expressed in the liver but is induced in alcohol-dependent liver disease (ALD)). This study sought to identify mechanisms whereby ethanol (EtOH) metabolism alters triglyceride accumulation and FABP4 production. Human hepatoma cells which were stably transfected to express alcohol dehydrogenase (ADH) or cytochrome P4502E1 (CYP2E1) were exposed to EtOH in the absence/presence of inhibitors of ADH (4-methylpyrazole) or CYP2E1 (chlormethiazole). Cells were analyzed for free fatty acid (FFA) content and FABP4 mRNA, then culture medium assayed for FABP4 levels. Cell lysates were analyzed for AMP-activated protein kinase-α (AMPKα), Acetyl-CoA carboxylase (ACC), sterol regulatory element binding protein-1c (SREBP-1c), and Lipin-1β activity and localization in the absence/presence of EtOH and pharmacological inhibitors. CYP2E1-EtOH metabolism led to increased FABP4 mRNA/protein expression and FFA accumulation. Analysis of signaling pathway activity revealed decreased AMPKα activation and increased nuclear-SREBP-1c localization following CYP2E1-EtOH metabolism. The role of AMPKα-SREBP-1c in regulating CYP2E1-EtOH-dependent FFA accumulation and increased FABP4 was confirmed using pharmacological inhibitors and over-expression of AMPKα. Inhibition of ACC or Lipin-1β failed to prevent FFA accumulation or changes in FABP4 mRNA expression or protein secretion. These data suggest that CYP2E1-EtOH metabolism inhibits AMPKα phosphorylation to stimulate FFA accumulation and FABP4 protein secretion via an SREBP-1c dependent mechanism.

Cytochrome P450 2E1-dependent hepatic ethanol metabolism induces fatty acid-binding protein 4 and steatosis

BACKGROUND

Hepatic steatosis is an early pathology of alcohol-associated liver disease (ALD). Fatty acid-binding protein-4 (FABP4, a FABP not normally produced in the liver) is secreted by hepatocytes in ALD and stimulates hepatoma proliferation and migration. This study sought to investigate the mechanism[s] by which hepatic ethanol metabolism regulates FABP4 and steatosis.

METHODS

Human hepatoma cells (HepG2/HuH7) and cells stably transfected to express cytochrome P450 2E1 (CYP2E1), were exposed to ethanol in the absence or presence of chlormethiazole (a CYP2E1-inhibitor; CMZ) and/or EX-527 (a sirtuin-1 [SIRT1] inhibitor). The culture medium was analyzed for ethanol metabolism and FABP4 protein abundance. Cells were analyzed for FABP4 mRNA expression, SIRT1 protein abundance, and neutral lipid accumulation. In parallel, cells were analyzed for forkhead box O1 [FOXO1], β-catenin, peroxisome proliferator-activated receptor-α [PPARα], and lipin-1α protein abundance in the absence or presence of ethanol and pharmacological inhibitors of the respective target proteins.

RESULTS

CYP2E1-dependent ethanol metabolism inhibited the amount of SIRT1 protein detected, concomitant with increased FABP4 mRNA expression, FABP4 protein secretion, and neutral lipid accumulation, effects abolished by CMZ. Analysis of pathways associated with lipid oxidation revealed increased FOXO1 nuclear localization and decreased β-catenin, PPARα, and lipin-1α protein levels in CYP2E1-expressing cells in the presence of ethanol. Pharmacological inhibition of SIRT1 mimicked the effects of ethanol, while inhibition of FOXO1 abrogated the effect of ethanol on FABP4 mRNA expression, FABP4 protein secretion, and neutral lipid accumulation in CYP2E1-expressing cells. Pharmacological inhibition of β-catenin, PPARα, or lipin-1α failed to alter the effects of ethanol on FABP4 or neutral lipid accumulation.

CONCLUSION

CYP2E1-dependent ethanol metabolism inhibits SIRT1-FOXO1 signaling, which leads to increased FABP4 mRNA expression, FABP4 protein secretion, and neutral lipid accumulation. These data suggest that FABP4 released from steatotic hepatocytes could play a role in promoting tumor cell expansion in the setting of ALD and represents a potential target for therapeutic intervention.

Inhibiting the Priming for Cancer in Li-Fraumeni Syndrome

Simple Summary

Li-Fraumeni Syndrome (LFS) is a rare cancer pre-disposition syndrome associated with a germline mutation in the TP53 tumour suppressor gene. People with LFS have a 90% chance of suffering one or more cancers in their lifetime. No treatments exist to reduce this cancer risk. This paper reviews the evidence for how cancers start in people with LFS and proposes that a series of commonly used non-cancer drugs, including metformin and aspirin, can help reduce that lifetime risk of cancer.

Abstract

The concept of the pre-cancerous niche applies the ‘seed and soil’ theory of metastasis to the initial process of carcinogenesis. TP53 is at the nexus of this process and, in the context of Li-Fraumeni Syndrome (LFS), is a key determinant of the conditions in which cancers are formed and progress. Important factors in the creation of the pre-cancerous niche include disrupted tissue homeostasis, cellular metabolism and chronic inflammation. While druggability of TP53 remains a challenge, there is evidence that drug re-purposing may be able to address aspects of pre-cancerous niche formation and thereby reduce the risk of cancer in individuals with LFS.

Raman Spectroscopy in Prostate Cancer: Techniques, Applications and Advancements

Optical techniques are widely used tools in the visualisation of biological species within complex matrices, including biopsies, tissue resections and biofluids. Raman spectroscopy is an emerging analytical approach that probes the molecular signature of endogenous cellular biomolecules under biocompatible conditions with high spatial resolution. Applications of Raman spectroscopy in prostate cancer include biopsy analysis, assessment of surgical margins and monitoring of treatment efficacy. The advent of advanced Raman imaging techniques, such as stimulated Raman scattering, is creating opportunities for real-time in situ evaluation of prostate cancer. This review provides a focus on the recent preclinical and clinical achievements in implementing Raman-based techniques, highlighting remaining challenges for clinical applications. The research and clinical results achieved through in vivo and ex vivo Raman spectroscopy illustrate areas where these evolving technologies can be best translated into clinical practice.

Norepinephrine Protects against Methamphetamine Toxicity through β2-Adrenergic Receptors Promoting LC3 Compartmentalization

Norepinephrine (NE) neurons and extracellular NE exert some protective effects against a variety of insults, including methamphetamine (Meth)-induced cell damage. The intimate mechanism of protection remains difficult to be analyzed in vivo. In fact, this may occur directly on target neurons or as the indirect consequence of NE-induced alterations in the activity of trans-synaptic loops. Therefore, to elude neuronal networks, which may contribute to these effects in vivo, the present study investigates whether NE still protects when directly applied to Meth-treated PC12 cells. Meth was selected based on its detrimental effects along various specific brain areas. The study shows that NE directly protects in vitro against Meth-induced cell damage. The present study indicates that such an effect fully depends on the activation of plasma membrane β2-adrenergic receptors (ARs). Evidence indicates that β2-ARs activation restores autophagy, which is impaired by Meth administration. This occurs via restoration of the autophagy flux and, as assessed by ultrastructural morphometry, by preventing the dissipation of microtubule-associated protein 1 light chain 3 (LC3) from autophagy vacuoles to the cytosol, which is produced instead during Meth toxicity. These findings may have an impact in a variety of degenerative conditions characterized by NE deficiency along with autophagy impairment.

Autophagy as a gateway for the effects of methamphetamine: From neurotransmitter release and synaptic plasticity to psychiatric and neurodegenerative disorders

As a major eukaryotic cell clearing machinery, autophagy grants cell proteostasis, which is key for neurotransmitter release, synaptic plasticity, and neuronal survival. In line with this, besides neuropathological events, autophagy dysfunctions are bound to synaptic alterations that occur in mental disorders, and early on, in neurodegenerative diseases. This is also the case of methamphetamine (METH) abuse, which leads to psychiatric disturbances and neurotoxicity. While consistently altering the autophagy machinery, METH produces behavioral and neurotoxic effects through molecular and biochemical events that can be recapitulated by autophagy blockade. These consist of altered physiological dopamine (DA) release, abnormal stimulation of DA and glutamate receptors, as well as oxidative, excitotoxic, and neuroinflammatory events. Recent molecular insights suggest that METH early impairs the autophagy machinery, though its functional significance remains to be investigated. Here we discuss evidence suggesting that alterations of DA transmission and autophagy are intermingled within a chain of events underlying behavioral alterations and neurodegenerative phenomena produced by METH. Understanding how METH alters the autophagy machinery is expected to provide novel insights into the neurobiology of METH addiction sharing some features with psychiatric disorders and parkinsonism.

Pathophysiologic Role of Neurotransmitters in Digestive Diseases

Neurotransmitters are special molecules that serve as messengers in chemical synapses between neurons, cells, or receptors, including catecholamines, serotonin, dopamine, and other neurotransmitters, which play an important role in both human physiology and pathology. Compelling evidence has indicated that neurotransmitters have an important physiological role in various digestive diseases. They act as ligands in combination with central or peripheral receptors, and transmits signals through chemical synapses, which are involved in regulating the physiological and pathological processes of the digestive tract organs. For instance, neurotransmitters regulate blood circulation and affect intestinal movement, nutrient absorption, the gastrointestinal innate immune system, and the microbiome. In this review, we will focus on the role of neurotransmitters in the pathogenesis of digestive tract diseases to provide novel therapeutic targets for new drug development in digestive diseases.

Lipin-1, a Versatile Regulator of Lipid Homeostasis, Is a Potential Target for Fighting Cancer

The rewiring of lipid metabolism is a major adaptation observed in cancer, and it is generally associated with the increased aggressiveness of cancer cells. Targeting lipid metabolism is therefore an appealing therapeutic strategy, but it requires a better understanding of the specific roles played by the main enzymes involved in lipid biosynthesis. Lipin-1 is a central regulator of lipid homeostasis, acting either as an enzyme or as a co-regulator of transcription. In spite of its important functions it is only recently that several groups have highlighted its role in cancer. Here, we will review the most recent research describing the role of lipin-1 in tumor progression when expressed by cancer cells or cells of the tumor microenvironment. The interest of its inhibition as an adjuvant therapy to amplify the effects of anti-cancer therapies will be also illustrated.

Repositioning metformin and propranolol for colorectal and triple negative breast cancers treatment

Drug repositioning refers to new uses for existing drugs outside the scope of the original medical indications. This approach fastens the process of drug development allowing finding effective drugs with reduced side effects and lower costs. Colorectal cancer (CRC) is often diagnosed at advanced stages, when the probability of chemotherapy resistance is higher. Triple negative breast cancer (TNBC) is the most aggressive type of breast cancer, highly metastatic and difficult to treat. For both tumor types, available treatments are generally associated to severe side effects. In our work, we explored the effect of combining metformin and propranolol, two repositioned drugs, in both tumor types. We demonstrate that treatment affects viability, epithelial-mesenchymal transition and migratory potential of CRC cells as we described before for TNBC. We show that combined treatment affects different steps leading to metastasis in TNBC. Moreover, combined treatment is also effective preventing the development of 5-FU resistant CRC. Our data suggest that combination of metformin and propranolol could be useful as a putative adjuvant treatment for both TNBC and CRC and an alternative for chemo-resistant CRC, providing a low-cost alternative therapy without associated toxicity.

Autophagy status as a gateway for stress-induced catecholamine interplay in neurodegeneration

The catecholamine-containing brainstem nuclei locus coeruleus (LC) and ventral tegmental area (VTA) are critically involved in stress responses. Alterations of catecholamine systems during chronic stress may contribute to neurodegeneration, including cognitive decline. Stress-related catecholamine alterations, while contributing to anxiety and depression, might accelerate neuronal degeneration by increasing the formation of toxic dopamine and norepinephrine by-products. These, in turn, may impair proteostasis within a variety of cortical and subcortical areas. In particular, the molecular events governing neurotransmission, neuroplasticity, and proteostasis within LC and VTA affect a variety of brain areas. Therefore, we focus on alterations of autophagy machinery in these nuclei as a relevant trigger in this chain of events. In fact, these catecholamine-containing areas are mostly prone to autophagy-dependent neurodegeneration. Thus, we propose a dynamic hypothesis according to which stress-induced autophagy alterations within the LC-VTA network foster a cascade towards early neurodegeneration within these nuclei.

β-Adrenoceptor regulates contraction and inflammatory cytokine expression of human bladder smooth muscle cells via autophagy under pathological hydrostatic pressure

AIMS

Abnormal intravesical pressure created by partial bladder outlet obstruction (PBOO) triggered the progression from chronic inflammation to fibrosis, initiating structural and functional alterations of bladder. To elucidate the underlying mechanisms of contraction and inflammatory response, we investigated the isolated human bladder smooth muscle cells (hBSMC) under pathological hydrostatic pressure (HP) mimicking the in vivo PBOO condition.

METHODS

hBSMCs were subjected to HP of 200 cm H₂ O to explore the contraction and inflammatory cytokine expression of hBSMC treated with β-adrenoceptors (ADRBs) and/or autophagy signaling pathway agonists and/or antagonists.

RESULTS

We showed that pathological HP induced the release of the proinflammatory cytokines, including monocyte chemotactic protein-1, regulated upon activation normal T cell expressed and secreted factor, and interleukin-6. HP downregulated ADRB2 and ADRB3 expression, which was consistent with the results of the PBOO rat model. ADRB2 or autophagy activation repressed pathological HP-induced proinflammatory cytokine production. ADRB2, ADRB3 or autophagy activation ameliorated the HP-enhanced contraction. The increased contraction and autophagy activity by ADRB2 agonist under HP conditions were reversed by pretreatment with antagonists of adenosine monophosphate-activated protein kinase (AMPK).

CONCLUSION

The present study provides evidence that the ADRB3 agonist suppresses hBSMC contraction under pathological HP conditions. Moreover, the ADRB2 agonist negatively regulates the contraction and inflammatory response of hBSMCs through AMPK/mTOR-mediated autophagy under pathological HP. These findings provide a theoretical basis for potential therapeutic strategies for patients with PBOO.

PEBP1 acts as a rheostat between prosurvival autophagy and ferroptotic death in asthmatic epithelial cells

Temporally harmonized elimination of damaged or unnecessary organelles and cells is a prerequisite of health. Under Type 2 inflammatory conditions, human airway epithelial cells (HAECs) generate proferroptotic hydroperoxy-arachidonoyl-phosphatidylethanolamines (HpETE-PEs) as proximate death signals. Production of 15-HpETE-PE depends on activation of 15-lipoxygenase-1 (15LO1) in complex with PE-binding protein-1 (PEBP1). We hypothesized that cellular membrane damage induced by these proferroptotic phospholipids triggers compensatory prosurvival pathways, and in particular autophagic pathways, to prevent cell elimination through programmed death. We discovered that PEBP1 is pivotal to driving dynamic interactions with both proferroptotic 15LO1 and the autophagic protein microtubule-associated light chain-3 (LC3). Further, the 15LO1-PEBP1-generated ferroptotic phospholipid, 15-HpETE-PE, promoted LC3-I lipidation to stimulate autophagy. This concurrent activation of autophagy protects cells from ferroptotic death and release of mitochondrial DNA. Similar findings are observed in Type 2 Hi asthma, where high levels of both 15LO1-PEBP1 and LC3-II are seen in HAECs, in association with low bronchoalveolar lavage fluid mitochondrial DNA and more severe disease. The concomitant activation of ferroptosis and autophagy by 15LO1-PEBP1 complexes and their hydroperoxy-phospholipids reveals a pathobiologic pathway relevant to asthma and amenable to therapeutic targeting.

Cell-Clearing Systems Bridging Repeat Expansion Proteotoxicity and Neuromuscular Junction Alterations in ALS and SBMA

The coordinated activities of autophagy and the ubiquitin proteasome system (UPS) are key to preventing the aggregation and toxicity of misfold-prone proteins which manifest in a number of neurodegenerative disorders. These include proteins which are encoded by genes containing nucleotide repeat expansions. In the present review we focus on the overlapping role of autophagy and the UPS in repeat expansion proteotoxicity associated with chromosome 9 open reading frame 72 (C9ORF72) and androgen receptor (AR) genes, which are implicated in two motor neuron disorders, amyotrophic lateral sclerosis (ALS) and spinal-bulbar muscular atrophy (SBMA), respectively. At baseline, both C9ORF72 and AR regulate autophagy, while their aberrantly-expanded isoforms may lead to a failure in both autophagy and the UPS, further promoting protein aggregation and toxicity within motor neurons and skeletal muscles. Besides proteotoxicity, autophagy and UPS alterations are also implicated in neuromuscular junction (NMJ) alterations, which occur early in both ALS and SBMA. In fact, autophagy and the UPS intermingle with endocytic/secretory pathways to regulate axonal homeostasis and neurotransmission by interacting with key proteins which operate at the NMJ, such as agrin, acetylcholine receptors (AChRs), and adrenergic beta2 receptors (B2-ARs). Thus, alterations of autophagy and the UPS configure as a common hallmark in both ALS and SBMA disease progression. The findings here discussed may contribute to disclosing overlapping molecular mechanisms which are associated with a failure in cell-clearing systems in ALS and SBMA.

Enhanced efficacy of propranolol therapy for infantile hemangiomas based on a mesoporous silica nanoplatform through mediating autophagy dysfunction

Infantile hemangioma is one of the most common vascular tumors, which might result in morbidity and mortality without timely intervention. Propranolol is currently the first-line therapy for hemangiomas, but its potential side effects and high frequency of administration make it urgent to develop a suitable drug delivery system for propranolol. In the present study, we formulated a propranolol delivery system based on mesoporous silica nanoparticles (PRN@MSN) and investigated the interplay between autophagic activities mediated by nanoparticles and improved therapeutic efficacy of PRN@MSN. The results showed that PRN@MSN nanoparticles exhibited higher cytotoxicity compared with free propranolol in vitro and in vivo, which could induce excessive autophagosome accumulation through increased autophagosome formation and impaired autophagic degradation. Inhibition of autophagy in the early stage could attenuate the cytotoxicity of PRN@MSN. ROS generation was essential for nanoparticle-mediated autophagy and cytotoxicity, and PRN@MSN-induced autophagy dysfunction could enhance endoplasmic reticulum (ER) stress in hemangioma stem cells. Our study revealed a promising PRN delivery system based on a mesoporous silica nanoplatform that could induce autophagy dysfunction with excessive autophagosome accumulation to promote the therapeutic efficacy of PRN therapy. PRN@MSN drug delivery system combined with autophagy modulation may act as a promising treatment pattern in the treatment of hemangiomas.

Abnormal expression of liver autophagy and apoptosis-related mRNA in fatty liver haemorrhagic syndrome and improvement function of resveratrol in laying hens

Fatty liver haemorrhagic syndrome (FLHS) is characterized by hepatic rupture and haemorrhage leading to sudden death in laying hens. Resveratrol (Res) is a natural polyphenol with antioxidant and anti-inflammatory effects that can ameliorate chronic liver disease. The aim of this study was to investigate the improved effect of Res on the altered expression of autophagy and apoptosis-related genes in laying hens with FLHS. A total of 144 healthy 150-day-old laying hens were randomly divided into four groups: control group (standard diet), HELP group (high-energy-low-protein (HELP) diet), HELP + Res group (HELP diet with 400 mg/kg Res) and Res group (standard diet with 400 mg/kg Res). Histopathological lesions of the liver and the mRNA levels of Beclin-1, Atg5, Atg7, p62, Bcl-2, Bax and Caspase-3 on days 40, 80, and 120 were measured. The results showed that lipid accumulation and hepatocyte damage in the HELP group were more serious than those in the HELP + Res group. The mRNA levels of Beclin-1, Atg5, Atg7, and Bcl-2 in the HELP and HELP + Res groups were strikingly declined (P < 0.01) compared to the control group, and their mRNA levels were markedly higher in HELP group than those in the HELP + Res group (P < 0.05). Additionally, the mRNA levels of p62, Bax and Caspase-3 were significantly increased in the HELP and HELP + Res groups (P < 0.01 or P < 0.05), but their mRNA levels in the HELP group were higher than those in the HELP + Res group (P < 0.05). Collectively, FLHS could induce severe lipid accumulation, abnormal mRNA levels of liver autophagy and apoptosis-related genes. Res as a dietary supplement could attenuate these abnormal changes.

Links between autophagy and disorders of glycogen metabolism - Perspectives on pathogenesis and possible treatments

The glycogen storage diseases are a group of inherited metabolic disorders that are characterized by specific enzymatic defects involving the synthesis or degradation of glycogen. Each disorder presents with a set of symptoms that are due to the underlying enzyme deficiency and the particular tissues that are affected. Autophagy is a process by which cells degrade and recycle unneeded or damaged intracellular components such as lipids, glycogen, and damaged mitochondria. Recent studies showed that several of the glycogen storage disorders have abnormal autophagy which can disturb normal cellular metabolism and/or mitochondrial function. Here, we provide a clinical overview of the glycogen storage disorders, a brief description of autophagy, and the known links between specific glycogen storage disorders and autophagy.

Autophagy-Based Hypothesis on the Role of Brain Catecholamine Response During Stress

Stressful events, similar to abused drugs, significantly affect the homeostatic balance of the catecholamine brain systems while activating compensation mechanisms to restore balance. In detail, norepinephrine (NE)- and dopamine (DA)-containing neurons within the locus coeruleus (LC) and ventral tegmental area (VTA), are readily and similarly activated by psychostimulants and stressful events involving neural processes related to perception, reward, cognitive evaluation, appraisal, and stress-dependent hormonal factors. Brain catecholamine response to stress results in time-dependent regulatory processes involving mesocorticolimbic circuits and networks, where LC-NE neurons respond more readily than VTA-DA neurons. LC-NE projections are dominant in controlling the forebrain DA-targeted areas, such as the nucleus accumbens (NAc) and medial pre-frontal cortex (mPFC). Heavy and persistent coping demand could lead to sustained LC-NE and VTA-DA neuronal activity, that, when persisting chronically, is supposed to alter LC-VTA synaptic connections. Increasing evidence has been provided indicating a role of autophagy in modulating DA neurotransmission and synaptic plasticity. This alters behavior, and emotional/cognitive experience in response to drug abuse and occasionally, to psychological stress. Thus, relevant information to address the role of stress and autophagy can be drawn from psychostimulants research. In the present mini-review we discuss the role of autophagy in brain catecholamine response to stress and its dysregulation. The findings here discussed suggest a crucial role of regulated autophagy in the response and adaptation of LC-NE and VTA-DA systems to stress.

Emerging therapeutic approaches for canine sarcomas: Pushing the boundaries beyond the conventional

Sarcomas represent a group of genomically chaotic, highly heterogenous tumours of mesenchymal origin with variable mutational load. Conventional therapy with surgery and radiation therapy is effective for managing small, low-grade sarcomas and remains the standard therapeutic approach. For advanced, high-grade, recurrent, or metastatic sarcomas, systemic chemotherapy provides minimal benefit, therefore, there is a drive to develop novel approaches. The discovery of "Coley's toxins" in the 19th century, and their use to stimulate the immune system supported the application of unconventional therapies for the treatment of sarcomas. While promising, this initial work was abandoned and treatment paradigm and disease course of sarcomas was largely unchanged for several decades. Exciting new therapies are currently changing treatment algorithms for advanced carcinomas and melanomas, and similar approaches are being applied to advance the field of sarcoma research. Recent discoveries in subtype-specific cancer biology and the identification of distinct molecular targets have led to the development of promising targeted strategies with remarkable potential to change the landscape of sarcoma therapy in dogs. The purpose of this review article is to describe the current standard of care and limitations as well as emerging approaches for sarcoma therapy that span many of the most active paradigms in oncologic research, including immunotherapies, checkpoint inhibitors, and drugs capable of cellular metabolic reprogramming.

Adrenergic modulation of AMPK‑dependent autophagy by chronic stress enhances cell proliferation and survival in gastric cancer

Epidemiological data show that chronic stress has adverse effects on the incidence and progression of cancer. As a critical target organ for stress hormones, the stomach is frequently subjected to stress-related injury. However, few reports regarding the association between stress and gastric cancer (GC) have been published. The present study aimed to investigate the effect of chronic stress on the growth and survival of GC, and the role of the autophagy process. A restraint-stress procedure over 21 days was used to establish a chronic stress mouse model. Subcutaneous xenografts and gastric orthotopic xenografts were established in BALB/c nude mice. Alzet osmotic minipumps containing either PBS or propranolol hydrochloride was inserted on the nape of the neck 7 days prior to the initiation of restraint stress. The presence of autophagosomes and autolysosomes were examined by electron microscopy. The stress hormone norepinephrine significantly enhanced the proliferation of GC cells. By inhibiting adrenoreceptor expression, it was demonstrated that β2-adrenergic receptor (ADRB2) was the specific β-adrenergic receptor subtype responsible for catecholamine release. In addition, it was demonstrated that the induction of autophagy was a novel consequence of β2-adrenergic activation in GC cells. This was demonstrated by the appearance of double-membrane vesicles, punctuate GFP-RFP-microtubule-associated protein 1 light chain 3 distribution in the cytoplasm and a corresponding increase in autophagic flux. Notably, norepinephrine-induced autophagy was shown to have a tumor-promoting role under conditions of chronic stress in vitro and in vivo. It was further demonstrated that, upon activation of cAMP-response element binding protein, chronic stress promoted autophagic flux through the adenosine 5′-monophosphate-activated protein kinase-unc-51 like autophagy activating kinase 1 (AMPK-ULK1) pathway. Tissue microarray analysis revealed a negative correlation between the expression of ADRB2 and autophagic marker p62/sequestosome-1 in GC tumor samples. Additionally, high protein levels of ADRB2 correlated positively with tumor, node, metastasis stage and poor prognosis in patients with GC. These results establish a novel pathway that chronic stress activates tumor-promoting autophagy to accelerate the progression of GC. The present study is the first, to the best of our knowledge, providing preclinical evidence that chronic stress serves a role in the progression of GC.

Genetic deletion of β2 adrenergic receptors exacerbates hepatocellular lipid accumulation in high-fat diet mice

β₂ Adrenergic receptors (β₂ARs) are G protein-coupled receptors (GPCRs) that are expressed in major insulin target tissues. β₂ARs play an important role in the regulation of lipid metabolism during aging; however, little is known about the significance of β₂ARs in the pathogenesis of hepatic fat accumulation in high-fat diet (HFD) mice. This study aims to examine the role of β₂AR in the development of nonalcoholic fatty liver disease (NAFLD) induced by HFD and the underlying mechanisms. Surprisingly, we found that genetic deletion of β₂AR significantly increased the liver weight of mice fed a HFD for 20 weeks compared to that of wild-type (WT) mice. Moreover, genetic deletion of β₂AR could aggravate HFD-induced liver lipid accumulation and liver injury in mice. Mechanistically, we demonstrated that β₂AR deletion significantly activated PPARγ/CD36 signaling via inactivation of the cAMP response element-binding (CREB) protein to facilitate hepatocellular lipid deposition in HFD mice. Together, our results identify β₂AR as a plausible therapeutic target for preventing or treating NAFLD.

Thyroid hormone receptor and ERRα coordinately regulate mitochondrial fission, mitophagy, biogenesis, and function

Thyroid hormone receptor β1 (THRB1) and estrogen-related receptor α (ESRRA; also known as ERRα) both play important roles in mitochondrial activity. To understand their potential interactions, we performed transcriptome and ChIP-seq analyses and found that many genes that were co-regulated by both THRB1 and ESRRA were involved in mitochondrial metabolic pathways. These included oxidative phosphorylation (OXPHOS), the tricarboxylic acid (TCA) cycle, and β-oxidation of fatty acids. TH increased ESRRA expression and activity in a THRB1-dependent manner through the induction of the transcriptional coactivator PPARGC1A (also known as PGC1α). Moreover, TH induced mitochondrial biogenesis, fission, and mitophagy in an ESRRA-dependent manner. TH also induced the expression of the autophagy-regulating kinase ULK1 through ESRRA, which then promoted DRP1-mediated mitochondrial fission. In addition, ULK1 activated the docking receptor protein FUNDC1 and its interaction with the autophagosomal protein MAP1LC3B-II to induce mitophagy. siRNA knockdown of ESRRA, ULK1, DRP1, or FUNDC1 inhibited TH-induced autophagic clearance of mitochondria through mitophagy and decreased OXPHOS. These findings show that many of the mitochondrial actions of TH are mediated through stimulation of ESRRA expression and activity, and co-regulation of mitochondrial turnover through the PPARGC1A-ESRRA-ULK1 pathway is mediated by their regulation of mitochondrial fission and mitophagy. Hormonal or pharmacologic induction of ESRRA expression or activity could improve mitochondrial quality in metabolic disorders.

Propranolol sensitizes prostate cancer cells to glucose metabolism inhibition and prevents cancer progression

Propranolol, a widely used non-selective beta-adrenergic receptor blocker, was recently shown to display anticancer properties. Its potential to synergize with certain drugs has been also outlined. However, it is necessary to take into account all the properties of propranolol to select a drug that could be efficiently combined with. Propranolol was reported to block the late phase of autophagy. Hence, we hypothesized that in condition enhancing autophagy flux, cancer cells should be especially sensitive to propranolol. 2DG, a glycolysis inhibitor, is an anti-tumor agent having limited effect in monotherapy notably due to induction of pro-survival autophagy. Here, we report that treatment of cancer cells with propranolol in combination with the glycolysis inhibitor 2DG induced a massive accumulation of autophagosome due to autophagy blockade. The propranolol +2DG treatment efficiently prevents prostate cancer cell proliferation, induces cell apoptosis, alters mitochondrial morphology, inhibits mitochondrial bioenergetics and aggravates ER stress in vitro and also suppresses tumor growth in vivo. Our study underlines for the first time the interest to take advantage of the ability of propranolol to inhibit autophagy to design new anti-cancer therapies.

Old wines in new bottles: Repurposing opportunities for Parkinson's disease

Parkinson's disease (PD) is a chronic progressive neurological disorder characterized by accumulation of Lewy bodies and profound loss of substantia nigra dopaminergic neurons. PD symptomatology is now recognized to include both cardinal motor as well as clinically significant non-motor symptoms. Despite intensive research, the current understanding of molecular mechanisms underlying neurodegeneration in PD is limited and has hampered the development of novel symptomatic and disease modifying therapies. The currently available treatment options are only partially or transiently effective and fail to restore the lost dopaminergic neurons or retard disease progression. Given the escalating drug development costs, lengthening timelines and declining R&D efficiency, industry and academia are increasingly focusing on ways to repurpose existing molecules as an accelerated route for drug discovery. The field of PD therapeutics is witnessing vigorous repurposing activity supported by big data analytics, computational models, and high-throughput drug screening systems. Here we review the mechanisms, efficacy, and safety of several emerging drugs currently aspiring to be repositioned for PD pharmacotherapy.

Cardiac Arrhythmias and Antiarrhythmic Drugs: An Autophagic Perspective

Degradation of cellular material by lysosomes is known as autophagy, and its main function is to maintain cellular homeostasis for growth, proliferation and survival of the cell. In recent years, research has focused on the characterization of autophagy pathways. Targeting of autophagy mediators has been described predominantly in cancer treatment, but also in neurological and cardiovascular diseases. Although the number of studies is still limited, there are indications that activity of autophagy pathways increases under arrhythmic conditions. Moreover, an increasing number of antiarrhythmic and non-cardiac drugs are found to affect autophagy pathways. We, therefore, suggest that future work should recognize the largely unaddressed effects of antiarrhythmic agents and other classes of drugs on autophagy pathway activation and inhibition.

Role of autophagy in cell-penetrating peptide transfection model

Cell-penetrating peptides (CPPs) uptake mechanism is still in need of more clarification to have a better understanding of their action in the mediation of oligonucleotide transfection. In this study, the effect on early events (1 h treatment) in transfection by PepFect14 (PF14), with or without oligonucleotide cargo on gene expression, in HeLa cells, have been investigated. The RNA expression profile was characterized by RNA sequencing and confirmed by qPCR analysis. The gene regulations were then related to the biological processes by the study of signaling pathways that showed the induction of autophagy-related genes in early transfection. A ligand library interfering with the detected intracellular pathways showed concentration-dependent effects on the transfection efficiency of splice correction oligonucleotide complexed with PepFect14, proving that the autophagy process is induced upon the uptake of complexes. Finally, the autophagy induction and colocalization with autophagosomes have been confirmed by confocal microscopy and transmission electron microscopy. We conclude that autophagy, an inherent cellular response process, is triggered by the cellular uptake of CPP-based transfection system. This finding opens novel possibilities to use autophagy modifiers in future gene therapy.

The Neuroanatomy of the Reticular Nucleus Locus Coeruleus in Alzheimer's Disease

Alzheimer’s Disease (AD) features the accumulation of β-amyloid and Tau aggregates, which deposit as extracellular plaques and intracellular neurofibrillary tangles (NFTs), respectively. Neuronal Tau aggregates may appear early in life, in the absence of clinical symptoms. This occurs in the brainstem reticular formation and mostly within Locus Coeruleus (LC), which is consistently affected during AD. LC is the main source of forebrain norepinephrine (NE) and it modulates a variety of functions including sleep-waking cycle, alertness, synaptic plasticity, and memory. The iso-dendritic nature of LC neurons allows their axons to spread NE throughout the whole forebrain. Likewise, a prion-like hypothesis suggests that Tau aggregates may travel along LC axons to reach out cortical neurons. Despite this timing is compatible with cross-sectional studies, there is no actual evidence for a causal relationship between these events. In the present mini-review, we dedicate special emphasis to those various mechanisms that may link degeneration of LC neurons to the onset of AD pathology. This includes the hypothesis that a damage to LC neurons contributes to the onset of dementia due to a loss of neuroprotective effects or, even the chance that, LC degenerates independently from cortical pathology. At the same time, since LC neurons are lost in a variety of neuropsychiatric disorders we considered which molecular mechanism may render these brainstem neurons so vulnerable.

β-Adrenergic induction of lipolysis in hepatocytes is inhibited by ethanol exposure

In liver steatosis (i.e. fatty liver), hepatocytes accumulate many large neutral lipid storage organelles known as lipid droplets (LDs). LDs are important in the maintenance of energy homeostasis, but the signaling mechanisms that stimulate LD metabolism in hepatocytes are poorly defined. In adipocytes, catecholamines target the β-adrenergic (β-AR)/cAMP pathway to activate cytosolic lipases and induce their recruitment to the LD surface. Therefore, the goal of this study was to determine whether hepatocytes, like adipocytes, also undergo cAMP-mediated lipolysis in response to β-AR stimulation. Using primary rat hepatocytes and human hepatoma cells, we found that treatment with the β-AR agent isoproterenol caused substantial LD loss via activation of cytosolic lipases adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL). β-Adrenergic stimulation rapidly activated PKA, which led to the phosphorylation of ATGL and HSL and their recruitment to the LD surface. To test whether this β-AR-dependent lipolysis pathway was altered in a model of alcoholic fatty liver, primary hepatocytes from rats fed a 6-week EtOH-containing Lieber-DeCarli diet were treated with cAMP agonists. Compared with controls, EtOH-exposed hepatocytes showed a drastic inhibition in β-AR/cAMP-induced LD breakdown and the phosphorylation of PKA substrates, including HSL. This observation was supported in VA-13 cells, an EtOH-metabolizing human hepatoma cell line, which displayed marked defects in both PKA activation and isoproterenol-induced ATGL translocation to the LD periphery. In summary, these findings suggest that β-AR stimulation mobilizes cytosolic lipases for LD breakdown in hepatocytes, and perturbation of this pathway could be a major consequence of chronic EtOH insult leading to fatty liver.

Reciprocal Crosstalk Between Autophagic and Endocrine Signaling in Metabolic Homeostasis

Autophagy is a cellular quality control and energy-providing process that is under strict control by intra- and extracellular stimuli. Recently, there has been an exponential increase in autophagy research and its implications for mammalian physiology. Autophagy deregulation is now being implicated in many human diseases, and its modulation has shown promising results in several preclinical studies. However, despite the initial discovery of autophagy as a hormone-regulated process by De Duve in the early 1960s, endocrine regulation of autophagy still remains poorly understood. In this review, we provide a critical summary of our present understanding of the basic mechanism of autophagy, its regulation by endocrine hormones, and its contribution to endocrine and metabolic homeostasis under physiological and pathological settings. Understanding the cross-regulation of hormones and autophagy on endocrine cell signaling and function will provide new insight into mammalian physiology as well as promote the development of new therapeutic strategies involving modulation of autophagy in endocrine and metabolic disorders.

Induction of autophagy improves hepatic lipid metabolism in glucose-6-phosphatase deficiency

BACKGROUND & AIMS

Glucose-6-phosphatase (G6Pase α, G6PC) deficiency, also known as von Gierke's disease or GSDIa, is the most common glycogen storage disorder. It is characterized by a decreased ability of the liver to convert glucose-6-phosphate (G6P) to glucose leading to glycogen and lipid over-accumulation progressing to liver failure and/or hepatomas and carcinomas. Autophagy of intracellular lipid stores (lipophagy) has been shown to stimulate fatty acid β-oxidation in hepatic cells. Thus, we examined autophagy and its effects on reducing hepatic lipid over-accumulation in several cell culture and animal models of GSDIa.

METHODS

Autophagy in G6PC-deficient hepatic cell lines, mice, and dogs was measured by Western blotting for key autophagy markers. Pro-autophagic Unc51-like kinase 1 (ULK1/ATG1) was overexpressed in G6PC-deficient hepatic cells, and lipid clearance and oxidative phosphorylation measured. G6PC(-/-) mice and GSDIa dogs were treated with rapamycin and assessed for liver function.

RESULTS

Autophagy was impaired in the cell culture, mouse, and canine models of GSDIa. Stimulation of the anti-autophagic mTOR, and inhibition of the pro-autophagic AMPK pathways occurred both in vitro and in vivo. Induction of autophagy by ULK1/ATG1 overexpression decreased lipid accumulation and increased oxidative phosphorylation in G6PC-deficient hepatic cells. Rapamycin treatment induced autophagy and decreased hepatic triglyceride and glycogen content in G6PC(-/-) mice, as well as reduced liver size and improved circulating markers of liver damage in GSDIa dogs.

CONCLUSIONS

Autophagy is impaired in GSDIa. Pharmacological induction of autophagy corrects hepatic lipid over-accumulation and may represent a new therapeutic strategy for GSDIa.

Hepatic FOXO1 Target Genes Are Co-regulated by Thyroid Hormone via RICTOR Protein Deacetylation and MTORC2-AKT Protein Inhibition

MTORC2-AKT is a key regulator of carbohydrate metabolism and insulin signaling due to its effects on FOXO1 phosphorylation. Interestingly, both FOXO1 and thyroid hormone (TH) have similar effects on carbohydrate and energy metabolism as well as overlapping transcriptional regulation of many target genes. Currently, little is known about the regulation of MTORC2-AKT or FOXO1 by TH. Accordingly, we performed hepatic transcriptome profiling in mice after FOXO1 knockdown in the absence or presence of TH, and we compared these results with hepatic FOXO1 and THRB1 (TRβ1) ChIP-Seq data. We identified a subset of TH-stimulated FOXO1 target genes that required co-regulation by FOXO1 and TH. TH activation of FOXO1 was directly linked to an increase in SIRT1-MTORC2 interaction and RICTOR deacetylation. This, in turn, led to decreased AKT and FOXO1 phosphorylation. Moreover, TH increased FOXO1 nuclear localization, DNA binding, and target gene transcription by reducing AKT-dependent FOXO1 phosphorylation in a THRB1-dependent manner. These events were associated with TH-mediated oxidative phosphorylation and NAD(+) production and suggested that downstream metabolic effects by TH can post-translationally activate other transcription factors. Our results showed that RICTOR/MTORC2-AKT can integrate convergent hormonal and metabolic signals to provide coordinated and sensitive regulation of hepatic FOXO1-target gene expression.