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Rutkowsky JM, Wong A, Toupadakis CA, Rutledge JC, Yellowley CE. Lipolysis products from triglyceride-rich lipoproteins induce stress protein ATF3 in osteoblasts. J Orthop Res 2024; 42:1033-1044. [PMID: 38044472 PMCID: PMC11009083 DOI: 10.1002/jor.25756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/07/2023] [Accepted: 11/28/2023] [Indexed: 12/05/2023]
Abstract
High fat diets overwhelm the physiological mechanisms for absorption, storage, and utilization of triglycerides (TG); consequently TG, TG-rich lipoproteins (TGRL), and TGRL remnants accumulate, circulate systemically, producing dyslipidemia. This associates with, or is causative for increased atherosclerotic cardiovascular risk, ischemic stroke, fatty liver disease, and pancreatitis. TGRL hydrolysis by endothelial surface-bound lipoprotein lipase (LPL) generates metabolites like free fatty acids which have proinflammatory properties. While osteoblasts utilize fatty acids as an energy source, dyslipidemia is associated with negative effects on the skeleton. In this study we investigated the effects of TGRL lipolysis products (TGRL-LP) on expression of a stress responsive transcription factor, termed activating transcription factor 3 (ATF3), reactive oxygen species (ROS), ATF3 target genes, and angiopoietin-like 4 (Angptl4) in osteoblasts. As ATF3 negatively associates with osteoblast differentiation, we also investigated the skeletal effects of global ATF3 deletion in mice. TGRL-LP increased expression of Atf3, proinflammatory proteins Ptgs2 and IL-6, and induced ROS in MC3T3-E1 osteoblastic cells. Angptl4 is an endogenous inhibitor of LPL which was transcriptionally induced by TGRL-LP, while recombinant Angptl4 prevented TG-driven Atf3 induction. Atf3 global knockout male mice demonstrated increased trabecular and cortical microarchitectural parameters. In summary, we find that TGRL-LP induce osteoblastic cell stress as evidenced by expression of ATF3, which may contribute to the negative impact of dyslipidemia in the skeleton. Further, concomitant induction of Angptl4 in osteoblasts might play a protective role by reducing local lipolysis.
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Affiliation(s)
| | - Alice Wong
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine
| | | | - John C. Rutledge
- Department of Internal Medicine (Cardiology), School of Medicine, University of California Davis, Davis, CA 95616
| | - Clare E. Yellowley
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine
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2
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Rutkowsky JM, Roland Z, Valenzuela A, Nguyen AB, Park HH, Six N, Dursun I, Kim K, Lein PJ, Ramsey JJ. The impact of continuous and intermittent ketogenic diets on cognitive behavior, motor function, and blood lipids in TgF344-AD rats. Aging (Albany NY) 2024; 16:5811-5828. [PMID: 38613791 PMCID: PMC11042947 DOI: 10.18632/aging.205741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 03/13/2024] [Indexed: 04/15/2024]
Abstract
Studies suggest that ketogenic diets (KD) may improve memory in mouse models of aging and Alzheimer's disease (AD). This study determined whether a continuous or intermittent KD (IKD) enhanced cognitive behavior in the TgF344-AD rat model of AD. At 6 months-old, TgF344-AD and wild-type (WT) littermates were placed on a control (CD), KD, or IKD (morning CD and afternoon KD) provided as two meals per day for 2 or 6 months. Cognitive and motor behavior and circulating β-hydroxybutyrate (BHB), AD biomarkers and blood lipids were assessed. Animals on a KD diet had elevated circulating BHB, with IKD levels intermediate to CD and KD. TgF344-AD rats displayed impaired spatial learning memory in the Barnes maze at 8 and 12 months of age and impaired motor coordination at 12 months of age. Neither KD nor IKD improved performance compared to CD. At 12 months of age, TgF344-AD animals had elevated blood lipids. IKD reduced lipids to WT levels with KD further reducing cholesterol below WT levels. This study shows that at 8 or 12 months of age, KD or IKD intervention did not improve measures of cognitive or motor behavior in TgF344-AD rats; however, both IKD and KD positively impacted circulating lipids.
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Affiliation(s)
- Jennifer M. Rutkowsky
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Zabrisky Roland
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Anthony Valenzuela
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - An B. Nguyen
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Heui Hye Park
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Natalie Six
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Ilknur Dursun
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
- Department of Physiology, School of Medicine, Istinye University, Istanbul 34396, Turkey
| | - Kyoungmi Kim
- Department of Public Health Sciences, School of Medicine, University of California, Davis, CA 95616, USA
| | - Pamela J. Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
- The MIND Institute, School of Medicine, University of California, Davis, CA 95817, USA
- Center for Neuroscience, University of California, Davis, CA 95616, USA
| | - Jon J. Ramsey
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Di Lucente J, Persico G, Zhou Z, Jin LW, Ramsey JJ, Rutkowsky JM, Montgomery CM, Tomilov A, Kim K, Giorgio M, Maezawa I, Cortopassi GA. Ketogenic diet and BHB rescue the fall of long-term potentiation in an Alzheimer's mouse model and stimulates synaptic plasticity pathway enzymes. Commun Biol 2024; 7:195. [PMID: 38366025 PMCID: PMC10873348 DOI: 10.1038/s42003-024-05860-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 01/26/2024] [Indexed: 02/18/2024] Open
Abstract
The Ketogenic Diet (KD) improves memory and longevity in aged C57BL/6 mice. We tested 7 months KD vs. control diet (CD) in the mouse Alzheimer's Disease (AD) model APP/PS1. KD significantly rescued Long-Term-Potentiation (LTP) to wild-type levels, not by changing Amyloid-β (Aβ) levels. KD's 'main actor' is thought to be Beta-Hydroxy-butyrate (BHB) whose levels rose significantly in KD vs. CD mice, and BHB itself significantly rescued LTP in APP/PS1 hippocampi. KD's 6 most significant pathways induced in brains by RNAseq all related to Synaptic Plasticity. KD induced significant increases in synaptic plasticity enzymes p-ERK and p-CREB in both sexes, and of brain-derived neurotrophic factor (BDNF) in APP/PS1 females. We suggest KD rescues LTP through BHB's enhancement of synaptic plasticity. LTP falls in Mild-Cognitive Impairment (MCI) of human AD. KD and BHB, because they are an approved diet and supplement respectively, may be most therapeutically and translationally relevant to the MCI phase of Alzheimer's Disease.
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Affiliation(s)
- Jacopo Di Lucente
- Department of Pathology and MIND Institute, University of California Davis Medical Center, Sacramento, CA, 95817, USA
| | - Giuseppe Persico
- Department of Experimental Oncology, European Institute of Oncology, IRCCS, 21041, Milan, Italy
| | - Zeyu Zhou
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, 95616, USA
| | - Lee-Way Jin
- Department of Pathology and MIND Institute, University of California Davis Medical Center, Sacramento, CA, 95817, USA
- Alzheimer's Disease Research Center, University of California Davis Medical Center, Sacramento, CA, 95817, USA
| | - Jon J Ramsey
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, 95616, USA
| | - Jennifer M Rutkowsky
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, 95616, USA
| | - Claire M Montgomery
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, 95616, USA
| | - Alexey Tomilov
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, 95616, USA
| | - Kyoungmi Kim
- Department of Public Health Sciences, School of Medicine, University of California Davis, Davis, CA, 95616, USA
| | - Marco Giorgio
- Department of Biomedical Sciences, University of Padova, 35131, Padova, Italy
| | - Izumi Maezawa
- Department of Pathology and MIND Institute, University of California Davis Medical Center, Sacramento, CA, 95817, USA.
- Alzheimer's Disease Research Center, University of California Davis Medical Center, Sacramento, CA, 95817, USA.
| | - Gino A Cortopassi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, 95616, USA.
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Zhou Z, Kim K, Ramsey JJ, Rutkowsky JM. Ketogenic diets initiated in late mid-life improved measures of spatial memory in male mice. GeroScience 2023; 45:2481-2494. [PMID: 36933143 PMCID: PMC10651563 DOI: 10.1007/s11357-023-00769-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 03/07/2023] [Indexed: 03/19/2023] Open
Abstract
Studies have shown ketogenic diets (KD) started from early middle-age improved health span and longevity in mice. KDs started later in life or administered intermittently may be more feasible and promote compliance. Therefore, this study sought to test if continuous or intermittent KDs started in late-middle-aged mice would improve cognition and motor function at advanced age. Eighteen-month-old male C57BL/6JN mice were assigned to an isocaloric control (CD), KD, or intermittent ketogenic (IKD, 3-day KD/week) diet. A panel of behavior tests were performed to assess cognitive and motor functions with aging. Y-maze alternation rate was higher for both IKD and KD mice at 23 months of age and for KD mice at 26 months indicating an improved spatial working memory. Twenty-six-month-old KD mice also showed better spatial learning memory in Barnes maze when compared to the CD. Improved grid wire hang performance was observed in aged IKD and KD versus CD mice indicating better muscle endurance under isometric contraction. A reduced level of circulating proinflammatory cytokines in aged KD (IL-6 and TNF-α) and IKD (IL-6) mice may contribute to the phenotypic improvements observed with these interventions. This study demonstrates that when initiated at late-middle age, the KD improved measures of spatial memory and grid wire hang performance in aged male mice, with IKD showing results intermediate to the CD and KD groups.
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Affiliation(s)
- Zeyu Zhou
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Kyoungmi Kim
- Department of Public Health Sciences, School of Medicine, University of California, Davis, CA, USA
| | - Jon J Ramsey
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
| | - Jennifer M Rutkowsky
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
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Pathak SJ, Zhou Z, Steffen D, Tran T, Ad Y, Ramsey JJ, Rutkowsky JM, Baar K. 2-month ketogenic diet preferentially alters skeletal muscle and augments cognitive function in middle aged female mice. Aging Cell 2022; 21:e13706. [PMID: 36148631 PMCID: PMC9577944 DOI: 10.1111/acel.13706] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 07/08/2022] [Accepted: 07/19/2022] [Indexed: 01/25/2023] Open
Abstract
The effect of a ketogenic diet (KD) on middle aged female mice is poorly understood as most of this work have been conducted in young female mice or diseased models. We have previously shown that an isocaloric KD started at middle age in male mice results in enhanced mitochondrial mass and function after 2 months on diet and improved cognitive behavior after being on diet for 14 months when compared with their control diet (CD) fed counterparts. Here, we aimed to investigate the effect of an isocaloric 2-month KD or CD on healthy 14-month-old female mice. At 16 months of age cognitive behavior tests were performed and then serum, skeletal muscle, cortex, and hippocampal tissues were collected for biochemical analysis. Two months on a KD resulted in enhanced cognitive behavior associated with anxiety, memory, and willingness to explore. The improved neurocognitive function was associated with increased PGC1α protein in the gastrocnemius (GTN) muscle and nuclear fraction. The KD resulted in a tissue specific increase in mitochondrial mass and kynurenine aminotransferase (KAT) levels in the GTN and soleus muscles, with a corresponding decrease in kynurenine and increase in kynurenic acid levels in serum. With KAT proteins being responsible for converting kynurenine into kynurenic acid, which is unable to cross the blood brain barrier and be turned into quinolinic acid-a potent neurotoxin, this study provides a potential mechanism of crosstalk between muscle and brain in mice on a KD that may contribute to improved cognitive function in middle-aged female mice.
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Affiliation(s)
- Suraj J. Pathak
- Department of Neurobiology, Physiology and BehaviorUniversity of CaliforniaDavisCaliforniaUSA
| | - Zeyu Zhou
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of CaliforniaDavisCaliforniaUSA
| | - Danielle Steffen
- Department of Neurobiology, Physiology and BehaviorUniversity of CaliforniaDavisCaliforniaUSA
| | - Tommy Tran
- Department of Neurobiology, Physiology and BehaviorUniversity of CaliforniaDavisCaliforniaUSA
| | - Yael Ad
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of CaliforniaDavisCaliforniaUSA
| | - Jon J. Ramsey
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of CaliforniaDavisCaliforniaUSA
| | - Jennifer M. Rutkowsky
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of CaliforniaDavisCaliforniaUSA
| | - Keith Baar
- Department of Neurobiology, Physiology and BehaviorUniversity of CaliforniaDavisCaliforniaUSA,Department of Physiology and Membrane Biology, School of MedicineUniversity of CaliforniaDavisCaliforniaUSA
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6
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O’Reilly J, Ono‐Moore KD, Chintapalli SV, Rutkowsky JM, Tolentino T, Lloyd KCK, Olfert IM, Adams SH. Sex differences in skeletal muscle revealed through fiber type, capillarity, and transcriptomics profiling in mice. Physiol Rep 2021; 9:e15031. [PMID: 34545692 PMCID: PMC8453262 DOI: 10.14814/phy2.15031] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 12/03/2022] Open
Abstract
Skeletal muscle anatomy and physiology are sexually dimorphic but molecular underpinnings and muscle-specificity are not well-established. Variances in metabolic health, fitness level, sedentary behavior, genetics, and age make it difficult to discern inherent sex effects in humans. Therefore, mice under well-controlled conditions were used to determine female and male (n = 19/sex) skeletal muscle fiber type/size and capillarity in superficial and deep gastrocnemius (GA-s, GA-d), soleus (SOL), extensor digitorum longus (EDL), and plantaris (PLT), and transcriptome patterns were also determined (GA, SOL). Summed muscle weight strongly correlated with lean body mass (r2 = 0.67, p < 0.0001, both sexes). Other phenotypes were muscle-specific: e.g., capillarity (higher density, male GA-s), myofiber size (higher, male EDL), and fiber type (higher, lower type I and type II prevalences, respectively, in female SOL). There were broad differences in transcriptomics, with >6000 (GA) and >4000 (SOL) mRNAs differentially-expressed by sex; only a minority of these were shared across GA and SOL. Pathway analyses revealed differences in ribosome biology, transcription, and RNA processing. Curation of sexually dimorphic muscle transcripts shared in GA and SOL, and literature datasets from mice and humans, identified 11 genes that we propose are canonical to innate sex differences in muscle: Xist, Kdm6a, Grb10, Oas2, Rps4x (higher, females) and Ddx3y, Kdm5d, Irx3, Wwp1, Aldh1a1, Cd24a (higher, males). These genes and those with the highest "sex-biased" expression in our study do not contain estrogen-response elements (exception, Greb1), but a subset are proposed to be regulated through androgen response elements. We hypothesize that innate muscle sexual dimorphism in mice and humans is triggered and then maintained by classic X inactivation (Xist, females) and Y activation (Ddx3y, males), with coincident engagement of X encoded (Kdm6a) and Y encoded (Kdm5d) demethylase epigenetic regulators that are complemented by modulation at some regions of the genome that respond to androgen.
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Affiliation(s)
- Juliana O’Reilly
- Division of Exercise PhysiologyWest Virginia University School of MedicineMorgantownWest VirginiaUSA
| | | | - Sree V. Chintapalli
- Arkansas Children’s Nutrition CenterLittle RockArkansasUSA
- Department of PediatricsUniversity of Arkansas for Medical SciencesLittle RockArkansasUSA
| | - Jennifer M. Rutkowsky
- Department of Molecular Biosciences, University of California Davis School of Veterinary MedicineDavisCaliforniaUSA
- Mouse Metabolic Phenotyping CenterUniversity of CaliforniaDavisCaliforniaUSA
| | - Todd Tolentino
- Mouse Metabolic Phenotyping CenterUniversity of CaliforniaDavisCaliforniaUSA
- Mouse Biology ProgramUniversity of CaliforniaDavisCaliforniaUSA
| | - K. C. Kent Lloyd
- Mouse Metabolic Phenotyping CenterUniversity of CaliforniaDavisCaliforniaUSA
- Mouse Biology ProgramUniversity of CaliforniaDavisCaliforniaUSA
- Department of SurgeryUniversity of California Davis School of MedicineSacramentoCaliforniaUSA
| | - I. Mark Olfert
- Division of Exercise PhysiologyWest Virginia University School of MedicineMorgantownWest VirginiaUSA
| | - Sean H. Adams
- Department of SurgeryUniversity of California Davis School of MedicineSacramentoCaliforniaUSA
- Center for Alimentary and Metabolic ScienceUniversity of California Davis School of MedicineSacramentoCaliforniaUSA
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7
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Zhou Z, Vidales J, González-Reyes JA, Shibata B, Baar K, Rutkowsky JM, Ramsey JJ. A 1-Month Ketogenic Diet Increased Mitochondrial Mass in Red Gastrocnemius Muscle, but Not in the Brain or Liver of Middle-Aged Mice. Nutrients 2021; 13:nu13082533. [PMID: 34444693 PMCID: PMC8401881 DOI: 10.3390/nu13082533] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 07/10/2021] [Accepted: 07/21/2021] [Indexed: 01/05/2023] Open
Abstract
Alterations in markers of mitochondrial content with ketogenic diets (KD) have been reported in tissues of rodents, but morphological quantification of mitochondrial mass using transmission electron microscopy (TEM), the gold standard for mitochondrial quantification, is needed to further validate these findings and look at specific regions of interest within a tissue. In this study, red gastrocnemius muscle, the prefrontal cortex, the hippocampus, and the liver left lobe were used to investigate the impact of a 1-month KD on mitochondrial content in healthy middle-aged mice. The results showed that in red gastrocnemius muscle, the fractional area of both subsarcolemmal (SSM) and intermyofibrillar (IMM) mitochondria was increased, and this was driven by an increase in the number of mitochondria. Mitochondrial fractional area or number was not altered in the liver, prefrontal cortex, or hippocampus following 1 month of a KD. These results demonstrate tissue-specific changes in mitochondrial mass with a short-term KD and highlight the need to study different muscle groups or tissue regions with TEM to thoroughly determine the effects of a KD on mitochondrial mass.
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Affiliation(s)
- Zeyu Zhou
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA; (Z.Z.); (J.V.)
| | - Jocelyn Vidales
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA; (Z.Z.); (J.V.)
| | - José A. González-Reyes
- Department of Cell Biology, Physiology and Immunology, Campus de Excelencia Internacional Agroalimentario, CeiA3, University of Córdoba, 14071 Córdoba, Spain;
| | - Bradley Shibata
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA 95616, USA;
| | - Keith Baar
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, CA 95616, USA;
| | - Jennifer M. Rutkowsky
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA; (Z.Z.); (J.V.)
- Correspondence: (J.M.R.); (J.J.R.)
| | - Jon J. Ramsey
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA; (Z.Z.); (J.V.)
- Correspondence: (J.M.R.); (J.J.R.)
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8
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Blackburn ML, Wankhade UD, Ono-Moore KD, Chintapalli SV, Fox R, Rutkowsky JM, Willis BJ, Tolentino T, Lloyd KCK, Adams SH. On the potential role of globins in brown adipose tissue: a novel conceptual model and studies in myoglobin knockout mice. Am J Physiol Endocrinol Metab 2021; 321:E47-E62. [PMID: 33969705 PMCID: PMC8321818 DOI: 10.1152/ajpendo.00662.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Myoglobin (Mb) regulates O2 bioavailability in muscle and heart as the partial pressure of O2 (Po2) drops with increased tissue workload. Globin proteins also modulate cellular NO pools, "scavenging" NO at higher Po2 and converting NO2- to NO as Po2 falls. Myoglobin binding of fatty acids may also signal a role in fat metabolism. Interestingly, Mb is expressed in brown adipose tissue (BAT), but its function is unknown. Herein, we present a new conceptual model that proposes links between BAT thermogenic activation, concurrently reduced Po2, and NO pools regulated by deoxy/oxy-globin toggling and xanthine oxidoreductase (XOR). We describe the effect of Mb knockout (Mb-/-) on BAT phenotype [lipid droplets, mitochondrial markers uncoupling protein 1 (UCP1) and cytochrome C oxidase 4 (Cox4), transcriptomics] in male and female mice fed a high-fat diet (HFD, 45% of energy, ∼13 wk), and examine Mb expression during brown adipocyte differentiation. Interscapular BAT weights did not differ by genotype, but there was a higher prevalence of mid-large sized droplets in Mb-/-. COX4 protein expression was significantly reduced in Mb-/- BAT, and a suite of metabolic/NO/stress/hypoxia transcripts were lower. All of these Mb-/--associated differences were most apparent in females. The new conceptual model, and results derived from Mb-/- mice, suggest a role for Mb in BAT metabolic regulation, in part through sexually dimorphic systems and NO signaling. This possibility requires further validation in light of significant mouse-to-mouse variability of BAT Mb mRNA and protein abundances in wild-type mice and lower expression relative to muscle and heart.NEW & NOTEWORTHY Myoglobin confers the distinct red color to muscle and heart, serving as an oxygen-binding protein in oxidative fibers. Less attention has been paid to brown fat, a thermogenic tissue that also expresses myoglobin. In a mouse knockout model lacking myoglobin, brown fat had larger fat droplets and lower markers of mitochondrial oxidative metabolism, especially in females. Gene expression patterns suggest a role for myoglobin as an oxygen/nitric oxide-sensor that regulates cellular metabolic and signaling pathways.
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Affiliation(s)
- Michael L Blackburn
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Umesh D Wankhade
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | | | - Sree V Chintapalli
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Renee Fox
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
| | - Jennifer M Rutkowsky
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, University of California, Davis, California
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
| | - Brandon J Willis
- Mouse Biology Program, University of California, Davis, California
| | - Todd Tolentino
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
- Mouse Biology Program, University of California, Davis, California
| | - K C Kent Lloyd
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
- Mouse Biology Program, University of California, Davis, California
- Department of Surgery, University of California Davis School of Medicine, Sacramento, California
| | - Sean H Adams
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
- Department of Surgery, University of California Davis School of Medicine, Sacramento, California
- Center for Alimentary and Metabolic Science, University of California Davis School of Medicine, Sacramento, California
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9
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Ono-Moore KD, Olfert IM, Rutkowsky JM, Chintapalli SV, Willis BJ, Blackburn ML, Williams DK, O'Reilly J, Tolentino T, Lloyd KCK, Adams SH. Metabolic physiology and skeletal muscle phenotypes in male and female myoglobin knockout mice. Am J Physiol Endocrinol Metab 2021; 321:E63-E79. [PMID: 33969704 PMCID: PMC8321820 DOI: 10.1152/ajpendo.00624.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Myoglobin (Mb) is a regulator of O2 bioavailability in type I muscle and heart, at least when tissue O2 levels drop. Mb also plays a role in regulating cellular nitric oxide (NO) pools. Robust binding of long-chain fatty acids and long-chain acylcarnitines to Mb, and enhanced glucose metabolism in hearts of Mb knockout (KO) mice, suggest additional roles in muscle intermediary metabolism and fuel selection. To evaluate this hypothesis, we measured energy expenditure (EE), respiratory exchange ratio (RER), body weight gain and adiposity, glucose tolerance, and insulin sensitivity in Mb knockout (Mb-/-) and wild-type (WT) mice challenged with a high-fat diet (HFD, 45% of calories). In males (n = 10/genotype) and females (n = 9/genotype) tested at 5-6, 11-12, and 17-18 wk, there were no genotype effects on RER, EE, or food intake. RER and EE during cold (10°C, 72 h), and glucose and insulin tolerance, were not different compared with within-sex WT controls. At ∼18 and ∼19 wk of age, female Mb-/- adiposity was ∼42%-48% higher versus WT females (P = 0.1). Transcriptomics analyses (whole gastrocnemius, soleus) revealed few consistent changes, with the notable exception of a 20% drop in soleus transferrin receptor (Tfrc) mRNA. Capillarity indices were significantly increased in Mb-/-, specifically in Mb-rich soleus and deep gastrocnemius. The results indicate that Mb loss does not have a major impact on whole body glucose homeostasis, EE, RER, or response to a cold challenge in mice. However, the greater adiposity in female Mb-/- mice indicates a sex-specific effect of Mb KO on fat storage and feed efficiency.NEW & NOTEWORTHY The roles of myoglobin remain to be elaborated. We address sexual dimorphism in terms of outcomes in response to the loss of myoglobin in knockout mice and perform, for the first time, a series of comprehensive metabolic studies under conditions in which fat is mobilized (high-fat diet, cold). The results highlight that myoglobin is not necessary and sufficient for maintaining oxidative metabolism and point to alternative roles for this protein in muscle and heart.
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Affiliation(s)
| | - I Mark Olfert
- Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, West Virginia
| | - Jennifer M Rutkowsky
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, University of California, Davis, California
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
| | - Sree V Chintapalli
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Brandon J Willis
- Mouse Biology Program, University of California, Davis, California
| | - Michael L Blackburn
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - D Keith Williams
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Juliana O'Reilly
- Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown, West Virginia
| | - Todd Tolentino
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
- Mouse Biology Program, University of California, Davis, California
| | - K C Kent Lloyd
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
- Mouse Biology Program, University of California, Davis, California
- Department of Surgery, University of California Davis School of Medicine, Sacramento, California
| | - Sean H Adams
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
- Department of Surgery, University of California Davis School of Medicine, Sacramento, California
- Center for Alimentary and Metabolic Science, University of California Davis School of Medicine, Sacramento, California
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10
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Ono-Moore KD, Rutkowsky JM, Pearson NA, Williams DK, Grobe JL, Tolentino T, Lloyd KCK, Adams SH. Coupling of energy intake and energy expenditure across a temperature spectrum: impact of diet-induced obesity in mice. Am J Physiol Endocrinol Metab 2020; 319:E472-E484. [PMID: 32691631 PMCID: PMC7509245 DOI: 10.1152/ajpendo.00041.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Obesity and its metabolic sequelae are implicated in dysfunction of the somatosensory, sympathetic, and hypothalamic systems. Because these systems contribute to integrative regulation of energy expenditure (EE) and energy intake (EI) in response to ambient temperature (Ta) changes, we hypothesized that diet-induced obesity (DIO) disrupts Ta-associated EE-EI coupling. C57BL/6N male mice were fed a high-fat diet (HFD; 45% kcal) or low-fat diet (LFD; 10% kcal) for ∼9.5 wk; HFD mice were then split into body weight (BWT) quartiles (n = 8 each) to study DIO-low gainers (Q1) versus -high gainers (Q4). EI and indirect calorimetry (IC) were measured over 3 days each at 10°C, 20°C, and 30°C. Responses did not differ between LFD, Q1, and Q4; EI and BWT-adjusted EE increased rapidly when transitioning toward 20°C and 10°C. In all groups, EI at 30°C was not reduced despite lower EE, resulting in positive energy balance and respiratory exchange ratios consistent with increased de novo lipogenesis, energy storage, and relative hyperphagia. We conclude that 1) systems controlling Ta-dependent acute EI/EE coupling remained intact in obese mice and 2) rapid coupling of EI/EE at cooler temperatures is an important adaptation to maintain energy stores and defend body temperature, but less critical at thermoneutrality. A post hoc analysis using digestible EI plus IC-calculated EE suggests that standard IC assumptions for EE calculation require further validation in the setting of DIO. The experimental paradigm provides a platform to query the hypothalamic, somatosensory, and sympathetic mechanisms that drive Ta-associated EI/EE coupling.
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Affiliation(s)
| | - Jennifer M Rutkowsky
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, University of California, Davis, California
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
| | - Nicole A Pearson
- Department of Pharmacology, University of Iowa, Carver College of Medicine, Iowa City, Iowa
| | - D Keith Williams
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Justin L Grobe
- Department of Physiology and Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Todd Tolentino
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
| | - K C Kent Lloyd
- Mouse Metabolic Phenotyping Center, University of California, Davis, California
- Department of Surgery, School of Medicine, University of California, Davis, California
| | - Sean H Adams
- Arkansas Children's Nutrition Center, Little Rock, Arkansas
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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11
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Rutkowsky JM, Knotts TA, Allen PD, Pessah IN, Ramsey JJ. Sex-specific alterations in whole body energetics and voluntary activity in heterozygous R163C malignant hyperthermia-susceptible mice. FASEB J 2020; 34:8721-8733. [PMID: 32367593 PMCID: PMC7383697 DOI: 10.1096/fj.202000403] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 04/20/2020] [Indexed: 11/20/2022]
Abstract
Malignant hyperthermia (MH) is characterized by induction of skeletal muscle hyperthermia in response to a dysregulated increase in myoplasmic calcium. Although altered energetics play a central role in MH, MH‐susceptible humans and mouse models are often described as having no phenotype until exposure to a triggering agent. The purpose of this study was to determine the influence of the R163C ryanodine receptor 1 mutation, a common MH mutation in humans, on energy expenditure, and voluntary wheel running in mice. Energy expenditure was measured by indirect respiration calorimetry in wild‐type (WT) and heterozygous R163C (HET) mice over a range of ambient temperatures. Energy expenditure adjusted for body weight or lean mass was increased (P < .05) in male, but not female, HET mice housed at 22°C or when housed at 28°C with a running wheel. In female mice, voluntary wheel running was decreased (P < .05) in the HET vs WT animals when analyzed across ambient temperatures. The thermoneutral zone was also widened in both male and female HET mice. The results of the study show that the R163C mutations alters energetics even at temperatures that do not typically induce MH.
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Affiliation(s)
- Jennifer M Rutkowsky
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Trina A Knotts
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Paul D Allen
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Jon J Ramsey
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA
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12
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Ono-Moore KD, Rutkowsky JM, Pearson NA, Grobe JL, Tolentino T, Ramsey JJ, Lloyd KK, Adams SH. Tight Regulation of Energy Intake and Expenditure Across a Temperature Spectrum is Disrupted at Thermoneutrality. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.08678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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13
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Rutkowsky JM, Lee LL, Puchowicz M, Golub MS, Befroy DE, Wilson DW, Anderson S, Cline G, Bini J, Borkowski K, Knotts TA, Rutledge JC. Reduced cognitive function, increased blood-brain-barrier transport and inflammatory responses, and altered brain metabolites in LDLr -/-and C57BL/6 mice fed a western diet. PLoS One 2018; 13:e0191909. [PMID: 29444171 PMCID: PMC5812615 DOI: 10.1371/journal.pone.0191909] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/12/2018] [Indexed: 12/20/2022] Open
Abstract
Recent work suggests that diet affects brain metabolism thereby impacting cognitive function. Our objective was to determine if a western diet altered brain metabolism, increased blood-brain barrier (BBB) transport and inflammation, and induced cognitive impairment in C57BL/6 (WT) mice and low-density lipoprotein receptor null (LDLr -/-) mice, a model of hyperlipidemia and cognitive decline. We show that a western diet and LDLr -/- moderately influence cognitive processes as assessed by Y-maze and radial arm water maze. Also, western diet significantly increased BBB transport, as well as microvessel factor VIII in LDLr -/- and microglia IBA1 staining in WT, both indicators of activation and neuroinflammation. Interestingly, LDLr -/- mice had a significant increase in 18F- fluorodeoxyglucose uptake irrespective of diet and brain 1H-magnetic resonance spectroscopy showed increased lactate and lipid moieties. Metabolic assessments of whole mouse brain by GC/MS and LC/MS/MS showed that a western diet altered brain TCA cycle and β-oxidation intermediates, levels of amino acids, and complex lipid levels and elevated proinflammatory lipid mediators. Our study reveals that the western diet has multiple impacts on brain metabolism, physiology, and altered cognitive function that likely manifest via multiple cellular pathways.
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Affiliation(s)
- Jennifer M. Rutkowsky
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
- * E-mail:
| | - Linda L. Lee
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, California, United States of America
| | - Michelle Puchowicz
- Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Mari S. Golub
- Department of Environmental Toxicology, University of California, Davis, California, United States of America
| | - Douglas E. Befroy
- Magnetic Resonance Research Center, Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Dennis W. Wilson
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Steven Anderson
- Department of Physiology and Membrane Biology, University of California, Davis, California, United States of America
| | - Gary Cline
- Department of Endocrinology, Yale University, New Haven, Connecticut, United States of America
| | - Jason Bini
- Yale PET Center, Department of Diagnostic Radiology, Yale University, New Haven, Connecticut, United States of America
| | - Kamil Borkowski
- West Coast Metabolomics Center, Genome Center, University of California, Davis, California, United States of America
| | - Trina A. Knotts
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - John C. Rutledge
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
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14
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Ono-Moore KD, Zhao L, Huang S, Kim J, Rutkowsky JM, Snodgrass RG, Schneider DA, Quon MJ, Graham JL, Havel PJ, Hwang DH. Transgenic mice with ectopic expression of constitutively active TLR4 in adipose tissues do not show impaired insulin sensitivity. Immun Inflamm Dis 2017; 5:526-540. [PMID: 28776958 PMCID: PMC5691308 DOI: 10.1002/iid3.162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 03/17/2017] [Accepted: 03/20/2017] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Chronic low-grade inflammation is associated with obesity and diabetes. However, what causes and mediates chronic inflammation in metabolic disorders is not well understood. Toll-like receptor 4 (TLR4) mediates both infection-induced and sterile inflammation by recognizing pathogen-associated molecular patterns and endogenous molecules, respectively. Saturated fatty acids can activate TLR4, and TLR4-deficient mice were protected from high fat diet (HFD)-induced obesity and insulin resistance, suggesting that TLR4-mediated inflammation may cause metabolic dysfunction, such as obesity and insulin resistance. METHODS We generated two transgenic (TG) mouse lines expressing a constitutively active TLR4 in adipose tissue and determined whether these TG mice would show increased insulin resistance. RESULTS TG mice fed a high fat or a normal chow diet did not exhibit increased insulin resistance compared to their wild-type controls despite increased localized inflammation in white adipose tissue. Furthermore, females of one TG line fed a normal chow diet had improved insulin sensitivity with reduction in both adiposity and body weight when compared with wild-type littermates. There were significant differences between female and male mice in metabolic biomarkers and mRNA expression in proinflammatory genes and negative regulators of TLR4 signaling, regardless of genotype and diet. CONCLUSIONS Together, these results suggest that constitutively active TLR4-induced inflammation in white adipose tissue is not sufficient to induce systemic insulin resistance, and that high fat diet-induced insulin resistance may require other signals in addition to TLR4-mediated inflammation.
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Affiliation(s)
- Kikumi D Ono-Moore
- Department of Nutrition, University of California, Davis, California.,Western Human Nutrition Research Center, Agricultural Research Service, USDA-ARS, Davis, California
| | - Ling Zhao
- Department of Nutrition, University of Tennessee, Knoxville, Tennessee
| | - Shurong Huang
- Western Human Nutrition Research Center, Agricultural Research Service, USDA-ARS, Davis, California
| | - Jeonga Kim
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama, Birmingham, Alabama
| | - Jennifer M Rutkowsky
- Department of Cardiovascular Medicine, University of California, Davis, California
| | - Ryan G Snodgrass
- Department of Nutrition, University of California, Davis, California.,Western Human Nutrition Research Center, Agricultural Research Service, USDA-ARS, Davis, California
| | - Dina A Schneider
- Western Human Nutrition Research Center, Agricultural Research Service, USDA-ARS, Davis, California
| | - Michael J Quon
- Division of Endocrinology, Diabetes and Nutrition, University of Maryland, School of Medicine, Baltimore, Maryland
| | - James L Graham
- Department of Nutrition, University of California, Davis, California
| | - Peter J Havel
- Department of Nutrition, University of California, Davis, California
| | - Daniel H Hwang
- Department of Nutrition, University of California, Davis, California.,Western Human Nutrition Research Center, Agricultural Research Service, USDA-ARS, Davis, California
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15
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Lee LL, Aung HH, Wilson DW, Anderson SE, Rutledge JC, Rutkowsky JM. Triglyceride-rich lipoprotein lipolysis products increase blood-brain barrier transfer coefficient and induce astrocyte lipid droplets and cell stress. Am J Physiol Cell Physiol 2017; 312:C500-C516. [PMID: 28077357 DOI: 10.1152/ajpcell.00120.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 01/06/2017] [Accepted: 01/09/2017] [Indexed: 12/19/2022]
Abstract
Elevation of blood triglycerides, primarily as triglyceride-rich lipoproteins (TGRL), has been linked to cerebrovascular inflammation, vascular dementia, and Alzheimer's disease (AD). Brain microvascular endothelial cells and astrocytes, two cell components of the neurovascular unit, participate in controlling blood-brain barrier (BBB) permeability and regulating neurovascular unit homeostasis. Our studies showed that infusion of high physiological concentrations of TGRL lipolysis products (TGRL + lipoprotein lipase) activate and injure brain endothelial cells and transiently increase the BBB transfer coefficient (Ki = permeability × surface area/volume) in vivo. However, little is known about how blood lipids affect astrocyte lipid accumulation and inflammation. To address this, we first demonstrated TGRL lipolysis products increased lipid droplet formation in cultured normal human astrocytes. We then evaluated the transcriptional pathways activated in astrocytes by TGRL lipolysis products and found upregulated stress and inflammatory-related genes including activating transcription factor 3 (ATF3), macrophage inflammatory protein-3α (MIP-3α), growth differentiation factor-15 (GDF15), and prostaglandin-endoperoxide synthase 2 (COX2). TGRL lipolysis products also activated the JNK/cJUN/ATF3 pathway, induced endoplasmic reticulum stress protein C/EBP homologous protein (CHOP), and the NF-κB pathway, while increasing secretion of MIP-3α, GDF15, and IL-8. Thus our results demonstrate TGRL lipolysis products increase the BBB transfer coefficient (Ki), induce astrocyte lipid droplet formation, activate cell stress pathways, and induce secretion of inflammatory cytokines. Our observations are consistent with evidence for lipid-induced neurovascular injury and inflammation, and we, therefore, speculate that lipid-induced astrocyte injury could play a role in cognitive decline.
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Affiliation(s)
- Linda L Lee
- Department of Internal Medicine, University of California, Davis, California
| | - Hnin H Aung
- Department of Internal Medicine, University of California, Davis, California
| | - Dennis W Wilson
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California; and
| | - Steven E Anderson
- Department of Physiology and Membrane Biology, University of California, Davis, California
| | - John C Rutledge
- Department of Internal Medicine, University of California, Davis, California
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16
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Rutkowsky JM, Knotts TA, Ono-Moore KD, McCoin CS, Huang S, Schneider D, Singh S, Adams SH, Hwang DH. Acylcarnitines activate proinflammatory signaling pathways. Am J Physiol Endocrinol Metab 2014; 306:E1378-87. [PMID: 24760988 PMCID: PMC4059985 DOI: 10.1152/ajpendo.00656.2013] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Incomplete β-oxidation of fatty acids in mitochondria is a feature of insulin resistance and type 2 diabetes mellitus (T2DM). Previous studies revealed that plasma concentrations of medium- and long-chain acylcarnitines (by-products of incomplete β-oxidation) are elevated in T2DM and insulin resistance. In a previous study, we reported that mixed D,L isomers of C12- or C14-carnitine induced an NF-κB-luciferase reporter gene in RAW 264.7 cells, suggesting potential activation of proinflammatory pathways. Here, we determined whether the physiologically relevant L-acylcarnitines activate classical proinflammatory signaling pathways and if these outcomes involve pattern recognition receptor (PRR)-associated pathways. Acylcarnitines induced the expression of cyclooxygenase-2 in a chain length-dependent manner in RAW 264.7 cells. L-C14 carnitine (5-25 μM), used as a representative acylcarnitine, stimulated the expression and secretion of proinflammatory cytokines in a dose-dependent manner. Furthermore, L-C14 carnitine induced phosphorylation of JNK and ERK, common downstream components of many proinflammatory signaling pathways including PRRs. Knockdown of MyD88, a key cofactor in PRR signaling and inflammation, blunted the proinflammatory effects of acylcarnitine. While these results point to potential involvement of PRRs, L-C14 carnitine promoted IL-8 secretion from human epithelial cells (HCT-116) lacking Toll-like receptors (TLR)2 and -4, and did not activate reporter constructs in TLR overexpression cell models. Thus, acylcarnitines have the potential to activate inflammation, but the specific molecular and tissue target(s) involved remain to be identified.
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Affiliation(s)
- Jennifer M Rutkowsky
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, California
| | - Trina A Knotts
- Obesity and Metabolism Research Unit, US Department of Agriculture-Agricultural Research Service Western Human Nutrition Research Center, Davis, California; Department of Nutrition, University of California, Davis, California
| | - Kikumi D Ono-Moore
- Department of Nutrition, University of California, Davis, California; Graduate Group in Nutritional Biology, University of California, Davis, California
| | - Colin S McCoin
- Graduate Group in Molecular, Cellular and Integrative Physiology, University of California, Davis, California; and
| | - Shurong Huang
- Immunity and Disease Prevention Research Unit, US Department of Agriculture-Agricultural Research Service Western Human Nutrition Research Center, Davis, California
| | - Dina Schneider
- Immunity and Disease Prevention Research Unit, US Department of Agriculture-Agricultural Research Service Western Human Nutrition Research Center, Davis, California
| | - Shamsher Singh
- Immunity and Disease Prevention Research Unit, US Department of Agriculture-Agricultural Research Service Western Human Nutrition Research Center, Davis, California
| | - Sean H Adams
- Obesity and Metabolism Research Unit, US Department of Agriculture-Agricultural Research Service Western Human Nutrition Research Center, Davis, California; Department of Nutrition, University of California, Davis, California; Graduate Group in Nutritional Biology, University of California, Davis, California; Graduate Group in Molecular, Cellular and Integrative Physiology, University of California, Davis, California; and
| | - Daniel H Hwang
- Department of Nutrition, University of California, Davis, California; Graduate Group in Nutritional Biology, University of California, Davis, California; Immunity and Disease Prevention Research Unit, US Department of Agriculture-Agricultural Research Service Western Human Nutrition Research Center, Davis, California
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17
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Ono‐Moore KD, Zhao L, Huang S, Kim J, Rutkowsky JM, Snodgrass RG, Schneider DA, Quon MJ, Hwang DH. Improved insulin sensitivity and reduced adiposity with aP2 driven TLR4 overexpression in transgenic mice. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1083.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kikumi D Ono‐Moore
- Department of NutritionUniversity of CaliforniaDavisCA
- Western Human Nutrition Res. Center, USDA‐ARSDavisCA
| | - Ling Zhao
- Department of NutritionUniversity of TennesseeKnoxvilleTN
| | - Shurong Huang
- Western Human Nutrition Res. Center, USDA‐ARSDavisCA
| | - Jeong‐a Kim
- Department of Cell BiologyDivision of Endocrinology, Diabetes, and MetabolismUniversity of AlabamaBirminghamAL
| | | | - Ryan G Snodgrass
- Department of NutritionUniversity of CaliforniaDavisCA
- Western Human Nutrition Res. Center, USDA‐ARSDavisCA
| | | | - Michael J Quon
- Department of MedicineDivision of Endocrinology, Diabetes & NutritionUniversity of MarylandBaltimoreMD
| | - Daniel H Hwang
- Department of NutritionUniversity of CaliforniaDavisCA
- Western Human Nutrition Res. Center, USDA‐ARSDavisCA
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18
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Huang S, Rutkowsky JM, Snodgrass RG, Ono-Moore KD, Schneider DA, Newman JW, Adams SH, Hwang DH. Saturated fatty acids activate TLR-mediated proinflammatory signaling pathways. J Lipid Res 2012; 53:2002-13. [PMID: 22766885 DOI: 10.1194/jlr.d029546] [Citation(s) in RCA: 422] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Toll-like receptor 4 (TLR4) and TLR2 were shown to be activated by saturated fatty acids (SFAs) but inhibited by docosahexaenoic acid (DHA). However, one report suggested that SFA-induced TLR activation in cell culture systems is due to contaminants in BSA used for solubilizing fatty acids. This report raised doubt about proinflammatory effects of SFAs. Our studies herein demonstrate that sodium palmitate (C16:0) or laurate (C12:0) without BSA solubilization induced phosphorylation of inhibitor of nuclear factor-κB α, c-Jun N-terminal kinase (JNK), p44/42 mitogen-activated-kinase (ERK), and nuclear factor-κB subunit p65, and TLR target gene expression in THP1 monocytes or RAW264.7 macrophages, respectively, when cultured in low FBS (0.25%) medium. C12:0 induced NFκB activation through TLR2 dimerized with TLR1 or TLR6, and through TLR4. Because BSA was not used in these experiments, contaminants in BSA have no relevance. Unlike in suspension cells (THP-1), BSA-solubilized C16:0 instead of sodium C16:0 is required to induce TLR target gene expression in adherent cells (RAW264.7). C16:0-BSA transactivated TLR2 dimerized with TLR1 or TLR6 and through TLR4 as seen with C12:0. These results and additional studies with the LPS sequester polymixin B and in MyD88(-/-) macrophages indicated that SFA-induced activation of TLR2 or TLR4 is a fatty acid-specific effect, but not due to contaminants in BSA or fatty acid preparations.
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Affiliation(s)
- Shurong Huang
- Western Human Nutrition Research Center, Agricultural Research Service, US Department of Agriculture, Department of Anatomy, Physiology and Cell Biology, University of California, Davis, CA, USA
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Hwang D, Huang S, Rutkowsky JM, Snodgrass RG, Ono-Moore KD, Schneider DA, Newman JW, Adams SH. Saturated fatty acids activate TLR‐mediated proinflammatory signaling pathways. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.364.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Daniel Hwang
- Western Human Nutrition Research CenterARS-USDADavisCA
- Department of NutritionUniversity of CaliforniaDavisCA
| | - Shurong Huang
- Western Human Nutrition Research CenterARS-USDADavisCA
| | | | | | | | | | - John W. Newman
- Western Human Nutrition Research CenterARS-USDADavisCA
- Department of NutritionUniversity of CaliforniaDavisCA
| | - Sean H. Adams
- Western Human Nutrition Research CenterARS-USDADavisCA
- Department of NutritionUniversity of CaliforniaDavisCA
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20
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Rutkowsky JM, Wallace BK, Wise PM, O'Donnell ME. Effects of estradiol on ischemic factor-induced astrocyte swelling and AQP4 protein abundance. Am J Physiol Cell Physiol 2011; 301:C204-12. [PMID: 21471464 DOI: 10.1152/ajpcell.00399.2010] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the early hours of ischemic stroke, cerebral edema forms as Na, Cl, and water are secreted across the blood-brain barrier (BBB) and astrocytes swell. We have shown previously that ischemic factors, including hypoxia, aglycemia, and arginine vasopressin (AVP), stimulate BBB Na-K-Cl cotransporter (NKCC) and Na/H exchanger (NHE) activities and that inhibiting NKCC and/or NHE by intravenous bumetanide and/or HOE-642 reduces edema and infarct in a rat model of ischemic stroke. Estradiol also reduces edema and infarct in this model and abolishes ischemic factor stimulation of BBB NKCC and NHE. There is evidence that NKCC and NHE also participate in ischemia-induced swelling of astrocytes. However, little is known about estradiol effects on astrocyte cell volume. In this study, we evaluated the effects of AVP (100 nM), hypoxia (7.5% O(2)), aglycemia, hypoxia (2%)/aglycemia [oxygen glucose deprivation (OGD)], and estradiol (1-100 nM) on astrocyte cell volume using 3-O-methyl-d-[(3)H]glucose equilibration methods. We found that AVP, hypoxia, aglycemia, and OGD (30 min to 5 h) each significantly increased astrocyte cell volume, and that estradiol (30-180 min) abolished swelling induced by AVP or hypoxia, but not by aglycemia or OGD. Bumetanide and/or HOE-642 also abolished swelling induced by AVP but not aglycemia. Abundance of aquaporin-4, known to participate in ischemia-induced astrocyte swelling, was significantly reduced following 7-day but not 2- or 3-h estradiol exposures. Our findings suggest that hypoxia, aglycemia, and AVP each contribute to ischemia-induced astrocyte swelling, and that the edema-attenuating effects of estradiol include reduction of hypoxia- and AVP-induced astrocyte swelling and also reduction of aquaporin-4 abundance.
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Affiliation(s)
- Jennifer M Rutkowsky
- Department of Physiology and Membrane Biology, University of California, Davis, California 95616, USA
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21
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Brillault J, Lam TI, Rutkowsky JM, Foroutan S, O'Donnell ME. Hypoxia effects on cell volume and ion uptake of cerebral microvascular endothelial cells. Am J Physiol Cell Physiol 2007; 294:C88-96. [PMID: 17942640 DOI: 10.1152/ajpcell.00148.2007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Increased transport of Na across an intact blood-brain barrier (BBB) contributes to cerebral edema formation in ischemic stroke. Our previous studies have shown that ischemic factors stimulate activity of a luminal BBB Na-K-Cl cotransporter, and we have hypothesized that during ischemia, the cotransporter together with the abluminal Na/K pump mediates increased transport of Na from blood into the brain. However, it is possible that elevated Na-K-Cl cotransporter activity could also cause cell swelling if it outpaces ion efflux pathways. The present study was conducted to evaluate the effects of hypoxia on intracellular volume of BBB cells. Cerebral microvascular endothelial cell (CMEC) monolayers were exposed to varying levels of hypoxia for 1 to 5 h in an O(2)-controlled glove box, and cell volume was assessed using 3-O-methyl-D-[(3)H]glucose and [(14)C]sucrose as markers of total and extracellular water space, respectively. Cells exposed to either 7.5%, 3%, or 1% O(2) showed gradual increases in volume (compared with 19% O(2) normoxic controls) that became significant after 3 or more hours. By ion chromatography methods, we also found that a 30-min exposure to 7.5% O(2) caused an increase in bumetanide-sensitive net Na uptake by the cells without increasing cell Na content. CMEC Na content was significantly increased, however, following 3 or more hours of exposure to 7.5% O(2). These findings are consistent with the hypothesis that during cerebral ischemia, the BBB Na-K-Cl cotransporter is stimulated to mediate transendothelial uptake of Na into the brain and that increased cotransporter activity also contributes to gradual swelling of the cells.
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Affiliation(s)
- Julien Brillault
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616, USA
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