Differential regulation of cardiac glucose and fatty acid uptake by endosomal pH and actin filaments

Insulin and contraction stimulate both cardiac glucose and long-chain fatty acid (LCFA) uptake via translocation of the substrate transporters GLUT4 and CD36, respectively, from intracellular compartments to the sarcolemma. Little is known about the role of vesicular trafficking elements in insulin- and contraction-stimulated glucose and LCFA uptake in the heart, especially whether certain trafficking elements are specifically involved in GLUT4 versus CD36 translocation. Therefore, we studied the role of coat proteins, actin- and microtubule-filaments and endosomal pH on glucose and LCFA uptake into primary cardiomyocytes under basal conditions and during stimulation with insulin or oligomycin (contraction-like AMP-activated protein kinase activator). Inhibition of coat protein targeting to Golgi/endosomes decreased insulin/oligomycin-stimulated glucose (−42%/−51%) and LCFA (−39%/−68%) uptake. Actin disruption decreased insulin/oligomycin-stimulated glucose uptake (−41%/−75%), while not affecting LCFA uptake. Microtubule disruption did not affect substrate uptake under any condition. Endosomal alkalinization increased basal sarcolemmal CD36 (2-fold), but not GLUT4, content, and concomitantly decreased basal intracellular membrane GLUT4 and CD36 content (−60% and −62%, respectively), indicating successful CD36 translocation and incomplete GLUT4 translocation. Additionally, endosomal alkalinization elevated basal LCFA uptake (1.4-fold) in a nonadditive manner to insulin/oligomycin, and decreased insulin/oligomycin-stimulated glucose uptake (−32%/−68%). In conclusion, 1) CD36 translocation, just like GLUT4 translocation, is a vesicle-mediated process depending on coat proteins, and 2) GLUT4 and CD36 trafficking are differentially dependent on endosomal pH and actin filaments. The latter conclusion suggests novel strategies to alter cardiac substrate preference as part of metabolic modulation therapy.

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Faculty Opinions recommendation of Differential regulation of cardiac glucose and fatty acid uptake by endosomal pH and actin filaments.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.2900959.2569057 ◽

2010 ◽

Author(s):

Peter Taylor

Keyword(s):

Fatty Acid ◽

Actin Filaments ◽

Fatty Acid Uptake ◽

Differential Regulation ◽

Acid Uptake ◽

Endosomal Ph

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Differential regulation of cardiac GLUT4-mediated glucose and CD36-mediated fatty acid uptake by endosomal pH and actin filaments

Chemistry and Physics of Lipids ◽

10.1016/j.chemphyslip.2010.05.035 ◽

2010 ◽

Vol 163 ◽

pp. S11

Author(s):

Laura K.M. Steinbusch ◽

Wino Wijnen ◽

Robert W. Schwenk ◽

Will A. Coumans ◽

Nicole T.H. Hoebers ◽

...

Keyword(s):

Fatty Acid ◽

Actin Filaments ◽

Fatty Acid Uptake ◽

Differential Regulation ◽

Acid Uptake ◽

Endosomal Ph

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Fatty acid uptake is preserved in chronically dysfunctional but viable myocardium

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1997.273.5.h2473 ◽

1997 ◽

Vol 273 (5) ◽

pp. H2473-H2480 ◽

Cited By ~ 5

Author(s):

Maija T. Mäki ◽

Merja T. Haaparanta ◽

Matti S. Luotolahti ◽

Pirjo Nuutila ◽

Liisa-Maria Voipio-Pulkki ◽

...

Keyword(s):

Fatty Acid ◽

Glucose Uptake ◽

Fatty Acid Uptake ◽

Viable Myocardium ◽

Acid Uptake ◽

Substrate Uptake ◽

Positron Emission ◽

Uptake Rates ◽

Major Coronary Artery

Glucose uptake appears preserved or even enhanced in the chronically dysfunctional but viable myocardium. However, the use of other fuels such as free fatty acids (FFA) remains unknown. We studied FFA uptake in the chronically dysfunctional but viable myocardium in seven patients with an occluded major coronary artery and a corresponding chronic wall motion abnormality but no previous infarction. Myocardial FFA uptake kinetics in the fasting state were measured with positron emission tomography (PET) and 14( R, S)-[18F]fluoro-6-thia-heptadecanoic acid ([18F]FTHA). The FFA uptake index was calculated by multiplying the fractional [18F]FTHA uptake with serum FFA concentration. Myocardial blood flow (MBF) was measured with [15O]H2O and PET. Myocardial viability was confirmed with a static18F-labeled 2-fluoro-2-deoxy-d-glucose PET imaging and a follow-up echocardiography in the revascularized patients. Regional MBF was slightly but not significantly lower in the dysfunctional compared with normal myocardial segments (0.76 ± 0.18 vs. 0.81 ± 0.14 ml ⋅ min−1 ⋅ g−1, means ± SD; P = 0.16). The fractional [18F]FTHA uptake rates [0.11 ± 0.03 vs. 0.11 ± 0.04 ml ⋅ g−1 ⋅ min−1; not significant (NS)], and the FFA uptake indexes (5.8 ± 1.7 vs. 5.8 ± 2.1 μmol ⋅ 100 g−1 ⋅ min−1; NS) were similar in the dysfunctional but viable and in the normal myocardial regions. Thus, in the chronically dysfunctional but viable (collateral-dependent) myocardium, the fatty acid uptake probed by [18F]FTHA appears preserved. Taken together with preserved glucose uptake, the results indicate that there is uncoupling of substrate uptake and mechanical function in the chronically dysfunctional but viable myocardium.

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FSMP-15. EVALUATING THE ROLE OF LONG-CHAIN FATTY ACID METABOLISM IN PROMOTING GLIOBLASTOMA GROWTH

Neuro-Oncology Advances ◽

10.1093/noajnl/vdab024.079 ◽

2021 ◽

Vol 3 (Supplement_1) ◽

pp. i19-i19

Author(s):

Divya Ravi ◽

Carmen del Genio ◽

Haider Ghiasuddin ◽

Arti Gaur

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Survival Rate ◽

Tumor Progression ◽

Acid Synthesis ◽

Normal Brain ◽

Acid Uptake ◽

Exogenous Fatty Acid ◽

Long Chain

Abstract Glioblastomas (GBM) or Stage IV gliomas, are the most aggressive of primary brain tumors and are associated with high mortality and morbidity. Patients diagnosed with this lethal cancer have a dismal survival rate of 14 months and a 5-year survival rate of 5.6% despite a multimodal therapeutic approach, including surgery, radiation therapy, and chemotherapy. Aberrant lipid metabolism, particularly abnormally active de novo fatty acid synthesis, is recognized to have a key role in tumor progression and chemoresistance in cancers. Previous studies have reported a high expression of fatty acid synthase (FASN) in patient tumors, leading to multiple investigations of FASN inhibition as a treatment strategy. However, none of these have developed as efficacious therapies. Furthermore, when we profiled FASN expression using The Cancer Genome Atlas (TCGA) we determined that high FASN expression in GBM patients did not confer a worse prognosis (HR: 1.06; p-value: 0.51) and was not overexpressed in GBM tumors compared to normal brain. Therefore, we need to reexamine the role of exogenous fatty acid uptake over de novofatty acid synthesis as a potential mechanism for tumor progression. Our study aims to measure and compare fatty acid oxidation (FAO) of endogenous and exogenous fatty acids between GBM patients and healthy controls. Using TCGA, we have identified the overexpression of multiple enzymes involved in mediating the transfer and activation of long-chain fatty acids (LCFA) in GBM tumors compared to normal brain tissue. We are currently conducting metabolic flux studies to (1) assess the biokinetics of LCFA degradation and (2) establish exogenous versus endogenous LCFA preferences between patient-derived primary GBM cells and healthy glial and immune cells during steady state and glucose-deprivation.

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Novel role of the ER/SR Ca2+ sensor STIM1 in the regulation of cardiac metabolism

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00544.2018 ◽

2019 ◽

Vol 316 (5) ◽

pp. H1014-H1026 ◽

Cited By ~ 5

Author(s):

Helen E. Collins ◽

Betty M. Pat ◽

Luyun Zou ◽

Silvio H. Litovsky ◽

Adam R. Wende ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Fatty Acid ◽

Pyruvate Dehydrogenase ◽

Glucose Utilization ◽

Cardiac Metabolism ◽

Mitochondrial Morphology ◽

Acid Uptake ◽

Stromal Interaction Molecule 1 ◽

First Time

The endoplasmic reticulum/sarcoplasmic reticulum Ca2+ sensor stromal interaction molecule 1 (STIM1), a key mediator of store-operated Ca2+ entry, is expressed in cardiomyocytes and has been implicated in regulating multiple cardiac processes, including hypertrophic signaling. Interestingly, cardiomyocyte-restricted deletion of STIM1 (crSTIM1-KO) results in age-dependent endoplasmic reticulum stress, altered mitochondrial morphology, and dilated cardiomyopathy in mice. Here, we tested the hypothesis that STIM1 deficiency may also impact cardiac metabolism. Hearts isolated from 20-wk-old crSTIM1-KO mice exhibited a significant reduction in both oxidative and nonoxidative glucose utilization. Consistent with the reduction in glucose utilization, expression of glucose transporter 4 and AMP-activated protein kinase phosphorylation were all reduced, whereas pyruvate dehydrogenase kinase 4 and pyruvate dehydrogenase phosphorylation were increased, in crSTIM1-KO hearts. Despite similar rates of fatty acid oxidation in control and crSTIM1-KO hearts ex vivo, crSTIM1-KO hearts contained increased lipid/triglyceride content as well as increased fatty acid-binding protein 4, fatty acid synthase, acyl-CoA thioesterase 1, hormone-sensitive lipase, and adipose triglyceride lipase expression compared with control hearts, suggestive of a possible imbalance between fatty acid uptake and oxidation. Insulin-mediated alterations in AKT phosphorylation were observed in crSTIM1-KO hearts, consistent with cardiac insulin resistance. Interestingly, we observed abnormal mitochondria and increased lipid accumulation in 12-wk crSTIM1-KO hearts, suggesting that these changes may initiate the subsequent metabolic dysfunction. These results demonstrate, for the first time, that cardiomyocyte STIM1 may play a key role in regulating cardiac metabolism. NEW & NOTEWORTHY Little is known of the physiological role of stromal interaction molecule 1 (STIM1) in the heart. Here, we demonstrate, for the first time, that hearts lacking cardiomyocyte STIM1 exhibit dysregulation of both cardiac glucose and lipid metabolism. Consequently, these results suggest a potentially novel role for STIM1 in regulating cardiac metabolism.

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The blood-brain barrier and protein-mediated fatty acid uptake: role of the blood-brain barrier as a metabolic barrier

Journal of Neurochemistry ◽

10.1111/jnc.14000 ◽

2017 ◽

Vol 141 (3) ◽

pp. 324-329 ◽

Cited By ~ 12

Author(s):

Eric J. Murphy

Keyword(s):

Fatty Acid ◽

Blood Brain Barrier ◽

Fatty Acid Uptake ◽

Brain Barrier ◽

Acid Uptake ◽

Blood Brain

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Free Fatty acids receptors (FFAR2 and FFAR3) control cell proliferation by regulating cellular glucose uptake

10.21203/rs.2.12250/v1 ◽

2019 ◽

Author(s):

Mohammad Aziz ◽

Saeed Al Mahri ◽

Amal Alghamdi ◽

Maaged AlAkiel ◽

Monira Al Aujan ◽

...

Keyword(s):

Colorectal Cancer ◽

Fatty Acids ◽

Cell Proliferation ◽

Fatty Acid ◽

Free Fatty Acid ◽

Free Fatty Acids ◽

Glucose Uptake ◽

Microarray Data ◽

Free Fatty Acid Receptors

Abstract Background Colorectal cancer is a worldwide problem which has been associated with changes in diet and lifestyle pattern. As a result of colonic fermentation of dietary fibres, short chain free fatty acids are generated which activate Free Fatty Acid Receptors 2 and 3 (FFAR2 and FFAR3). FFAR2 and FFAR3 genes are abundantly expressed in colonic epithelium and play an important role in the metabolic homeostasis of colonic epithelial cells. Earlier studies point to the involvement of FFAR2 in colorectal carcinogenesis. Methods Transcriptome analysis console was used to analyse microarray data from patients and cell lines. We employed shRNA mediated down regulation of FFAR2 and FFAR3 genes which was assessed using qRT-PCR. Assays for glucose uptake and cAMP generation was done along with immunofluorescence studies. For measuring cell proliferation, we employed real time electrical impedance based assay available from xCelligence. Results Microarray data analysis of colorectal cancer patient samples showed a significant down regulation of FFAR2 gene expression. This prompted us to study the FFAR2 in colorectal cancer. Since, FFAR3 shares significant structural and functional homology with FFAR2, we knocked down both these receptors in colorectal cancer cell line HCT 116. These modified cell lines exhibited higher proliferation rate and were found to have increased glucose uptake as well as increased level of GLUT1. Since, FFAR2 and FFAR3 signal through G protein subunit (Gαi), knockdown of these receptors was associated with increased cAMP. Inhibition of PKA did not alter the growth and proliferation of these cells indicating a mechanism independent of cAMP/PKA pathway. Conclusion: Our results suggest role of FFAR2/FFAR3 genes in increased proliferation of colon cancer cells via enhanced glucose uptake and exclude the role of protein kinase A mediated cAMP signalling. Alternate pathways could be involved that would ultimately result in increased cell proliferation as a result of down regulated FFAR2/FFAR3 genes. This study paves the way to understand the mechanism of action of short chain free fatty acid receptors in colorectal cancer.

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