scholarly journals The decrease of intraflagellar transport impairs sensory perception and metabolism in ageing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yincong Zhang ◽  
Xiaona Zhang ◽  
Yumin Dai ◽  
Mengjiao Song ◽  
Yifei Zhou ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Protein Kinase ◽  
Sensory Neurons ◽  
Intraflagellar Transport ◽  
Sensory Perception ◽  
Metabolic Homeostasis ◽  
Impaired Metabolism ◽  
Sensory Cilia ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

AbstractSensory perception and metabolic homeostasis are known to deteriorate with ageing, impairing the health of aged animals, while mechanisms underlying their deterioration remain poorly understood. The potential interplay between the declining sensory perception and the impaired metabolism during ageing is also barely explored. Here, we report that the intraflagellar transport (IFT) in the cilia of sensory neurons is impaired in the aged nematode Caenorhabditis elegans due to a daf-19/RFX-modulated decrease of IFT components. We find that the reduced IFT in sensory cilia thus impairs sensory perception with ageing. Moreover, we demonstrate that whereas the IFT-dependent decrease of sensory perception in aged worms has a mild impact on the insulin/IGF-1 signalling, it remarkably suppresses AMP-activated protein kinase (AMPK) signalling across tissues. We show that upregulating daf-19/RFX effectively enhances IFT, sensory perception, AMPK activity and autophagy, promoting metabolic homeostasis and longevity. Our study determines an ageing pathway causing IFT decay and sensory perception deterioration, which in turn disrupts metabolism and healthy ageing.

scholarly journals The decrease of intraflagellar transport impairs sensory perception and metabolism in ageing

2020 ◽  
Author(s):  
Yincong Zhang ◽  
Xiaona Zhang ◽  
Yumin Dai ◽  
Mengjiao Song ◽  
Yifei Zhou ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Protein Kinase ◽  
Sensory Neurons ◽  
Intraflagellar Transport ◽  
Sensory Perception ◽  
Metabolic Homeostasis ◽  
Impaired Metabolism ◽  
Sensory Cilia ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

Abstract Sensory perception and metabolic homeostasis deteriorate with ageing, impairing the health of aged animals. However, the mechanisms underlying their deterioration remain poorly understood. The potential interplay between the declining sensory perception and the impaired metabolism during ageing is also barely explored. Here, we report that the intraflagellar transport (IFT) in the cilia of sensory neurons is impaired in the aged nematode Caenorhabditis elegans due to a daf-19/RFX-modulated decrease of IFT components. The impaired IFT in sensory cilia in turn causes the deterioration of sensory perception with ageing. Moreover, whereas the IFT-dependent decrease of sensory perception in aged worms has a mild impact on the insulin/IGF-1 signalling, it remarkably suppresses AMP-activated protein kinase (AMPK) signalling across tissues. Upregulating daf-19/RFX effectively enhances IFT, sensory perception, AMPK activity and autophagy, promoting metabolic homeostasis and longevity. Our studies have uncovered an ageing pathway causing IFT decay and sensory perception deterioration, which in turn disrupts metabolism and healthy ageing.

scholarly journals Chlamydomonas Kinesin-II–dependent Intraflagellar Transport (IFT): IFT Particles Contain Proteins Required for Ciliary Assembly in Caenorhabditis elegans Sensory Neurons

1998 ◽  
Vol 141 (4) ◽  
pp. 993-1008 ◽  
Author(s):  
Douglas G. Cole ◽  
Dennis R. Diener ◽  
Amy L. Himelblau ◽  
Peter L. Beech ◽  
Jason C. Fuster ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Sensory Neurons ◽  
Intraflagellar Transport ◽  
Retrograde Transport ◽  
Temperature Sensitive ◽  
Basal Bodies ◽  
Sensitive Mutant ◽  
Sensory Cilia ◽  
A Subunit ◽  
Dependent Transport

We previously described a kinesin-dependent movement of particles in the flagella of Chlamydomonas reinhardtii called intraflagellar transport (IFT) (Kozminski, K.G., K.A. Johnson, P. Forscher, and J.L. Rosenbaum. 1993. Proc. Natl. Acad. Sci. USA. 90:5519–5523). When IFT is inhibited by inactivation of a kinesin, FLA10, in the temperature-sensitive mutant, fla10, existing flagella resorb and new flagella cannot be assembled. We report here that: (a) the IFT-associated FLA10 protein is a subunit of a heterotrimeric kinesin; (b) IFT particles are composed of 15 polypeptides comprising two large complexes; (c) the FLA10 kinesin-II and IFT particle polypeptides, in addition to being found in flagella, are highly concentrated around the flagellar basal bodies; and, (d) mutations affecting homologs of two of the IFT particle polypeptides in Caenorhabditis elegans result in defects in the sensory cilia located on the dendritic processes of sensory neurons. In the accompanying report by Pazour, G.J., C.G. Wilkerson, and G.B. Witman (1998. J. Cell Biol. 141:979–992), a Chlamydomonas mutant (fla14) is described in which only the retrograde transport of IFT particles is disrupted, resulting in assembly-defective flagella filled with an excess of IFT particles. This microtubule- dependent transport process, IFT, defined by mutants in both the anterograde (fla10) and retrograde (fla14) transport of isolable particles, is probably essential for the maintenance and assembly of all eukaryotic motile flagella and nonmotile sensory cilia.

scholarly journals Glucose regulates AMP-activated protein kinase activity and gene expression in clonal, hypothalamic neurons expressing proopiomelanocortin: additive effects of leptin or insulin

2007 ◽  
Vol 192 (3) ◽  
pp. 605-614 ◽  
Author(s):  
Fang Cai ◽  
Armen V Gyulkhandanyan ◽  
Michael B Wheeler ◽  
Denise D Belsham
Keyword(s):  
Protein Kinase ◽  
Energy Homeostasis ◽  
Cell Model ◽  
Neuronal Cell ◽  
Cell Types ◽  
Glucose Sensing ◽  
Protein Kinase Activity ◽  
Energy Status ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

The mammalian hypothalamus comprises an array of phenotypically distinct cell types that interpret peripheral signals of energy status and, in turn, elicits an appropriate response to maintain energy homeostasis. We used a clonal representative hypothalamic cell model expressing proopiomelanocortin (POMC; N-43/5) to study changes in AMP-activated protein kinase (AMPK) activity and glucose responsiveness. We have demonstrated the presence of cellular machinery responsible for glucose sensing in the cell line, including glucokinase, glucose transporters, and appropriate ion channels. ATP-sensitive potassium channels were functional and responded to glucose. The N-43/5 POMC neurons may therefore be an appropriate cell model to study glucose-sensing mechanisms in the hypothalamus. In N-43/5 POMC neurons, increasing glucose concentrations decreased phospho-AMPK activity. As a relevant downstream effect, we found that POMC transcription increased with 2.8 and 16.7 mM glucose. Upon addition of leptin, with either no glucose or with 5 mM glucose, we found that leptin decreased AMPK activity in N-43/5 POMC neurons, but had no significant effect at 25 mM glucose, whereas insulin decreased AMPK activity at only 5 mM glucose. These results demonstrate that individual hypothalamic neuronal cell types, such as the POMC neuron, can have distinct responses to peripheral signals that relay energy status to the brain, and will therefore be activated uniquely to control neuroendocrine function.

scholarly journals Adrenaline is a critical mediator of acute exercise-induced AMP-activated protein kinase activation in adipocytes

2007 ◽  
Vol 403 (3) ◽  
pp. 473-481 ◽  
Author(s):  
Ho-Jin Koh ◽  
Michael F. Hirshman ◽  
Huamei He ◽  
Yangfeng Li ◽  
Yasuko Manabe ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase Activity ◽  
Chronic Exercise ◽  
Rat Adipocytes ◽  
Compound C ◽  
Isolated Adipocytes ◽  
Ampk Activity ◽  
Exercise Induced ◽  
Amp Activated Protein Kinase

Exercise increases AMPK (AMP-activated protein kinase) activity in human and rat adipocytes, but the underlying molecular mechanisms and functional consequences of this activation are not known. Since adrenaline (epinephrine) concentrations increase with exercise, in the present study we hypothesized that adrenaline activates AMPK in adipocytes. We show that a single bout of exercise increases AMPKα1 and α2 activities and ACC (acetyl-CoA carboxylase) Ser79 phosphorylation in rat adipocytes. Similarly to exercise, adrenaline treatment in vivo increased AMPK activities and ACC phosphorylation. Pre-treatment of rats with the β-blocker propranolol fully blocked exercise-induced AMPK activation. Increased AMPK activity with exercise and adrenaline treatment in vivo was accompanied by an increased AMP/ATP ratio. Adrenaline incubation of isolated adipocytes also increased the AMP/ATP ratio and AMPK activities, an effect blocked by propranolol. Adrenaline incubation increased lipolysis in isolated adipocytes, and Compound C, an AMPK inhibitor, attenuated this effect. Finally, a potential role for AMPK in the decreased adiposity associated with chronic exercise was suggested by marked increases in AMPKα1 and α2 activities in adipocytes from rats trained for 6 weeks. In conclusion, both acute and chronic exercise are significant regulators of AMPK activity in rat adipocytes. Our findings suggest that adrenaline plays a critical role in exercise-stimulated AMPKα1 and α2 activities in adipocytes, and that AMPK can function in the regulation of lipolysis.

AMPK activation with AICAR provokes an acute fall in plasma [K+]

2008 ◽  
Vol 294 (1) ◽  
pp. C126-C135 ◽  
Author(s):  
Dan Zheng ◽  
Anjana Perianayagam ◽  
Donna H. Lee ◽  
M. Douglas Brannan ◽  
Li E. Yang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Infusion Rate ◽  
Extracellular Fluid ◽  
Ampk Activation ◽  
Conscious Rats ◽  
Significant Fall ◽  
Ampk Phosphorylation ◽  
Atp Levels ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK), activated by an increase in intracellular AMP-to-ATP ratio, stimulates pathways that can restore ATP levels. We tested the hypothesis that AMPK activation influences extracellular fluid (ECF) K+ homeostasis. In conscious rats, AMPK was activated with 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) infusion: 38.4 mg/kg bolus then 4 mg·kg−1·min−1 infusion. Plasma [K+] and [glucose] both dropped at 1 h of AICAR infusion and [K+] dropped to 3.3 ± 0.04 mM by 3 h, linearly related to the increase in muscle AMPK phosphorylation. AICAR treatment did not increase urinary K+ excretion. AICAR lowered [K+] whether plasma [K+] was chronically elevated or lowered. The K+ infusion rate needed to maintain baseline plasma [K+] reached 15.7 ± 1.3 μmol K+·kg−1·min−1 between 120 and 180 min AICAR infusion. In mice expressing a dominant inhibitory form of AMPK in the muscle (Tg-KD1), baseline [K+] was not different from controls (4.2 ± 0.1 mM), but the fall in plasma [K+] in response to AICAR (0.25 g/kg) was blunted: [K+] fell to 3.6 ± 0.1 in controls and to 3.9 ± 0.1 mM in Tg-KD1, suggesting that ECF K+ redistributes, at least in part, to muscle ICF. In summary, these findings illustrate that activation of AMPK activity with AICAR provokes a significant fall in plasma [K+] and suggest a novel mechanism for redistributing K+ from ECF to ICF.

scholarly journals Characterization of the Role of AMP-Activated Protein Kinase in the Regulation of Glucose-Activated Gene Expression Using Constitutively Active and Dominant Negative Forms of the Kinase

2000 ◽  
Vol 20 (18) ◽  
pp. 6704-6711 ◽  
Author(s):  
Angela Woods ◽  
Dalila Azzout-Marniche ◽  
Marc Foretz ◽  
Silvie C. Stein ◽  
Patricia Lemarchand ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Kinase ◽  
Fatty Acid Synthase ◽  
Physiological Role ◽  
Rat Hepatocytes ◽  
Dominant Negative ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase ◽  
Constitutively Active

ABSTRACT In the liver, glucose induces the expression of a number of genes involved in glucose and lipid metabolism, e.g., those encoding L-type pyruvate kinase and fatty acid synthase. Recent evidence has indicated a role for the AMP-activated protein kinase (AMPK) in the inhibition of glucose-activated gene expression in hepatocytes. It remains unclear, however, whether AMPK is involved in the glucose induction of these genes. In order to study further the role of AMPK in regulating gene expression, we have generated two mutant forms of AMPK. One of these (α1312) acts as a constitutively active kinase, while the other (α1DN) acts as a dominant negative inhibitor of endogenous AMPK. We have used adenovirus-mediated gene transfer to express these mutants in primary rat hepatocytes in culture in order to determine their effect on AMPK activity and the transcription of glucose-activated genes. Expression of α1312 increased AMPK activity in hepatocytes and blocked completely the induction of a number of glucose-activated genes in response to 25 mM glucose. This effect is similar to that observed following activation of AMPK by 5-amino-imidazolecarboxamide riboside. Expression of α1DN markedly inhibited both basal and stimulated activity of endogenous AMPK but had no effect on the transcription of glucose-activated genes. Our results suggest that AMPK is involved in the inhibition of glucose-activated gene expression but not in the induction pathway. This study demonstrates that the two mutants we have described will provide valuable tools for studying the wider physiological role of AMPK.

Physiological modulation of CFTR activity by AMP-activated protein kinase in polarized T84 cells

2003 ◽  
Vol 284 (5) ◽  
pp. C1297-C1308 ◽  
Author(s):  
Kenneth R. Hallows ◽  
Gary P. Kobinger ◽  
James M. Wilson ◽  
Lee A. Witters ◽  
J. Kevin Foskett
Keyword(s):  
Protein Kinase ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Physiological Role ◽  
Dominant Negative ◽  
T84 Cells ◽  
Physiological Relevance ◽  
Polarized Epithelia ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-activated, ATP-gated Cl− channel and cellular conductance regulator, but the detailed mechanisms of CFTR regulation and its regulation of other transport proteins remain obscure. We previously identified the metabolic sensor AMP-activated protein kinase (AMPK) as a novel protein interacting with CFTR and found that AMPK phosphorylated CFTR and inhibited CFTR-dependent whole cell conductances when coexpressed with CFTR in Xenopus oocytes. To address the physiological relevance of the CFTR-AMPK interaction, we have now studied polarized epithelia and have evaluated the localization of endogenous AMPK and CFTR and measured CFTR activity with modulation of AMPK activity. By immunofluorescent imaging, AMPK and CFTR share an overlapping apical distribution in several rat epithelial tissues, including nasopharynx, submandibular gland, pancreas, and ileum. CFTR-dependent short-circuit currents ( Isc ) were measured in polarized T84 cells grown on permeable supports, and several independent methods were used to modulate endogenous AMPK activity. Activation of endogenous AMPK with the cell-permeant adenosine analog 5-amino-4-imidazolecarboxamide-1-β-d-ribofuranoside (AICAR) inhibited forskolin-stimulated CFTR-dependent I sc in nonpermeabilized monolayers and monolayers with nystatin permeabilization of the basolateral membrane. Raising intracellular AMP concentration in monolayers with basolateral membranes permeabilized with α-toxin also inhibited CFTR, an effect that was unrelated to adenosine receptors. Finally, overexpression of a kinase-dead mutant AMPK-α1 subunit (α1-K45R) enhanced forskolin-stimulated I sc in polarized T84 monolayers, consistent with a dominant-negative reduction in the inhibition of CFTR by endogenous AMPK. These results indicate that AMPK plays a physiological role in modulating CFTR activity in polarized epithelia and suggest a novel paradigm for the coupling of ion transport to cellular metabolism.

scholarly journals Mitochondria-derived ROS activate AMP-activated protein kinase (AMPK) indirectly

2018 ◽  
Vol 293 (44) ◽  
pp. 17208-17217 ◽  
Author(s):  
Elizabeth C. Hinchy ◽  
Anja V. Gruszczyk ◽  
Robin Willows ◽  
Naveenan Navaratnam ◽  
Andrew R. Hall ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Fluorescent Proteins ◽  
Adenine Nucleotide ◽  
Direct Action ◽  
Cysteine Residues ◽  
Ros Production ◽  
Α Subunit ◽  
Atp Production ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

Mitochondrial reactive oxygen species (ROS) production is a tightly regulated redox signal that transmits information from the organelle to the cell. Other mitochondrial signals, such as ATP, are sensed by enzymes, including the key metabolic sensor and regulator, AMP-activated protein kinase (AMPK). AMPK responds to the cellular ATP/AMP and ATP/ADP ratios by matching mitochondrial ATP production to demand. Previous reports proposed that AMPK activity also responds to ROS, by ROS acting on redox-sensitive cysteine residues (Cys-299/Cys-304) on the AMPK α subunit. This suggests an appealing model in which mitochondria fine-tune AMPK activity by both adenine nucleotide–dependent mechanisms and by redox signals. Here we assessed whether physiological levels of ROS directly alter AMPK activity. To this end we added exogenous hydrogen peroxide (H2O2) to cells and utilized the mitochondria-targeted redox cycler MitoParaquat to generate ROS within mitochondria without disrupting oxidative phosphorylation. Mitochondrial and cytosolic thiol oxidation was assessed by measuring peroxiredoxin dimerization and by redox-sensitive fluorescent proteins. Replacing the putative redox-active cysteine residues on AMPK α1 with alanines did not alter the response of AMPK to H2O2. In parallel with measurements of AMPK activity, we measured the cell ATP/ADP ratio. This allowed us to separate the effects on AMPK activity due to ROS production from those caused by changes in this ratio. We conclude that AMPK activity in response to redox changes is not due to direct action on AMPK itself, but is a secondary consequence of redox effects on other processes, such as mitochondrial ATP production.

Hypoxia and AMP independently regulate AMP-activated protein kinase activity in heart

2005 ◽  
Vol 288 (5) ◽  
pp. H2412-H2421 ◽  
Author(s):  
Markus Frederich ◽  
Li Zhang ◽  
James A. Balschi
Keyword(s):  
Protein Kinase ◽  
Metabolic Inhibitors ◽  
Protein Kinase Activity ◽  
Α Subunit ◽  
Rat Hearts ◽  
Upstream Kinase ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

The hypothesis was tested that hypoxia increases AMP-activated protein kinase (AMPK) activity independently of AMP concentration ([AMP]) in heart. In isolated perfused rat hearts, cytosolic [AMP] was changed from 0.2 to 16 μM using metabolic inhibitors during both normal oxygenation (95% O2-5% CO2, normoxia) and limited oxygenation (95% N2-5% CO2, hypoxia). Total AMPK activity measured in vitro ranged from 2 to 40 pmol·min−1·mg protein−1 in normoxic hearts and from 5 to 55 pmol·min−1·mg protein−1 in hypoxic hearts. The dependence of the in vitro total AMPK activity on the in vivo cytosolic [AMP] was determined by fitting the measurements from individual hearts to a hyperbolic equation. The [AMP] resulting in half-maximal total AMPK activity ( A0.5) was 3 ± 1 μM for hypoxic hearts and 28 ± 13 μM for normoxic hearts. The A0.5 for α2-isoform AMPK activity was 2 ± 1 μM for hypoxic hearts and 13 ± 8 μM for normoxic hearts. Total AMPK activity correlated with the phosphorylation of the Thr172 residue of the AMPK α-subunit. In potassium-arrested hearts perfused with variable O2 content, α-subunit Thr172 phosphorylation increased at O2 ≤ 21% even though [AMP] was <0.3 μM. Thus hypoxia or O2 ≤ 21% increased AMPK phosphorylation and activity independently of cytosolic [AMP]. The hypoxic increase in AMPK activity may result from either direct phosphorylation of Thr172 by an upstream kinase or reduction in the A0.5 for [AMP].

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