Role of Akt signaling pathway regulation in the speckled mousebird (Colius striatus) during torpor displays tissue specific responses

Green, Stuart R.; Al-attar, Rasha; McKechnie, Andrew E.; Naidoo, S.; Storey, Kenneth B.

doi:10.1016/j.cellsig.2020.109763

Cited by 3 publications

(10 citation statements)

References 68 publications

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“…Whereas there have been a variety of studies investigating the physiology of mousebird torpor, the underlying biochemistry of the phenomenon has only recently begun to receive attention. A recent study by the current authors demonstrated that the Akt-mTOR signaling pathway is regulated in a tissue-specific manner in C. striatus during torpor to restrict energetically expensive metabolic processes such as protein translation (Green et al, 2020).…”

Section: Introductionmentioning

confidence: 78%

“…Speckled mousebirds, 10 animals total, were captured near Pretoria, South Africa, using baited walk-in traps as described previously (Green et al, 2020). Birds were housed and assigned to either a control euthermic group or a heterothermic torpor group (five in each group) at the University of Pretoria Experimental Farm.…”

Section: Animal Treatmentsmentioning

confidence: 99%

“…Homogenization of the tissue samples (liver, skeletal [pectoral] muscle, heart, brain) from four randomly selected animals in each group was carried out according to previously described protocols using the 1× lysis buffer provided with the Luminex ® assay kits with the addition of 1 mM Na 3 VO 4 , 10 mM NaF, 10 mM β-glycerophosphate, 10 μl/ml of protease inhibitor cocktail (BioShop, # PIC002.1) to ensure protein stability and retention of the original phosphorylation state (Green et al, 2020). Samples were then sonicated for 15 s and incubated on ice for 30 min with intermittent mixing every 10 min.…”

Section: Protein Extract Preparationmentioning

confidence: 99%

“…Relative levels of different phosphorylated residues (S232, S293, S300) and the total amount of PDH in the mousebird samples were quantified using the Multi-Species Pyruvate Dehydrogenase Complex Magnetic Bead Panel (EMD Millipore; PDHMAG13K) assay kit and were read with a Luminex 100 ® machine. The manufacturer's protocols were followed as described in a previous paper (Green et al, 2020). The Luminex ® assay kit makes use of fluorescent color-coded beads that are bound to antibodies that recognize a phosphorylation site of interest.…”

Section: Multiplex Assaymentioning

confidence: 99%

“…Western blots used 25 μg of protein for each sample loaded into a 10% SDS-PAGE electrophoresis gel and run at 180 V for 65 min. Proteins were transferred to a PVDF membrane according to previously described methods and subsequently blocked with 2% w:v skim milk for 30 min (Green et al, 2020). After removing the milk solution the blots were washed 3 × 5 min each time with TBST (20 mM Tris base, 140 mM NaCl, pH 7.6, 0.05% v:v Tween-20) and the blots were incubated overnight in 1:1000 diluted anti-PDHK antibody (GeneTex, GTX107405).…”

Section: Western Blotsmentioning

confidence: 99%

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Phosphorylation status of pyruvate dehydrogenase in the mousebird Colius striatus undergoing torpor

et al. 2021

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Torpor is a heterothermic response that occurs in some animals to reduce metabolic expenditure. The speckled mousebird (Colius striatus) belongs to one of the few avian taxa possessing the capacity for pronounced torpor, entering a hypometabolic state with concomitant decreases in body temperature in response to reduced food access or elevated thermoregulatory energy requirements. The pyruvate dehydrogenase complex (PDC) is a crucial site regulating metabolism by bridging glycolysis and the Krebs cycle. Three highly conserved phosphorylation sites are found within the E1 enzyme of the complex that inhibit PDC activity and reduce the flow of carbohydrate substrates into the mitochondria. The current study demonstrates a marked increase in S232 phosphorylation during torpor in liver, heart, and skeletal muscle of C. striatus. The increase in S232 phosphorylation during torpor was particularly notable in skeletal muscle where levels were ~49-fold higher in torpid birds compared to controls. This was in contrast to the other two phosphorylation sites (S293 and S300) which remained consistently phosphorylated regardless of tissue. The relevant PDH kinase (PDHK1) known to phosphorylate S232 was found to be substantially upregulated (~5-fold change) in the muscle during torpor as well as increasing moderately in the liver (~2.2-fold increase). Additionally, in the heart, a slight (~23%) decrease in total PDH levels was noted. Taken together the phosphorylation changes in PDH suggest that inhibition of the complex is a common feature across several tissues in the mousebird during torpor and that this regulation is mediated at a specific residue.

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Section: Introductionmentioning

confidence: 78%

Section: Animal Treatmentsmentioning

confidence: 99%

Section: Protein Extract Preparationmentioning

confidence: 99%

Section: Multiplex Assaymentioning

confidence: 99%

Section: Western Blotsmentioning

confidence: 99%

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Phosphorylation status of pyruvate dehydrogenase in the mousebird Colius striatus undergoing torpor

et al. 2021

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Torpor‐responsive microRNAs in the heart of the Monito del monte, Dromiciops gliroides

et al. 2023

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The marsupial Monito del monte (Dromiciops gliroides) utilizes both daily and seasonal bouts of torpor to preserve energy and prolong survival during periods of cold and unpredictable food availability. Torpor involves changes in cellular metabolism, including specific changes to gene expression that is coordinated in part, by the posttranscriptional gene silencing activity of microRNAs (miRNA). Previously, differential miRNA expression has been identified in D. gliroides liver and skeletal muscle; however, miRNAs in the heart of Monito del monte remained unstudied. In this study, the expression of 82 miRNAs was assessed in the hearts of active and torpid D. gliroides, finding that 14 were significantly differentially expressed during torpor. These 14 miRNAs were then used in bioinformatic analyses to identify Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were predicted to be most affected by these differentially expressed miRNAs. Overexpressed miRNAs were predicted to primarily regulate glycosaminoglycan biosynthesis, along with various signaling pathways such as Phosphoinositide‐3‐kinase/protein kinase B and transforming growth factor‐β. Similarly, signaling pathways including phosphatidylinositol and Hippo were predicted to be regulated by the underexpression of miRNAs during torpor. Together, these results suggest potential molecular adaptations that protect against irreversible tissue damage and enable continued cardiac and vascular function despite hypothermia and limited organ perfusion during torpor.

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Cool birds: first evidence of energy-saving nocturnal torpor in free-living common swifts Apus apus resting in their nests

et al. 2022

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Daily torpor is a means of saving energy by controlled lowering of the metabolic rate (MR) during resting, usually coupled with a decrease in body temperature. We studied nocturnal daily torpor under natural conditions in free-living common swifts Apus apus resting in their nests as a family using two non-invasive approaches. First, we monitored nest temperature ( T nest ) in up to 50 occupied nests per breeding season in 2010–2015. Drops in T nest were the first indication of torpor. Among 16 673 observations, we detected 423 events of substantial drops in T nest of on average 8.6°C. Second, we measured MR of the families inside nest-boxes prepared for calorimetric measurements during cold periods in the breeding seasons of 2017 and 2018. We measured oxygen consumption and carbon dioxide production using a mobile indirect respirometer and calculated the percentage reduction in MR. During six torpor events observed, MR was gradually reduced by on average 56% from the reference value followed by a decrease in T nest of on average 7.6°C. By contrast, MR only decreased by about 33% on nights without torpor. Our field data gave an indication of daily torpor, which is used as a strategy for energy saving in free-living common swifts.

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Role of Akt signaling pathway regulation in the speckled mousebird (Colius striatus) during torpor displays tissue specific responses

Cited by 3 publications

References 68 publications

Phosphorylation status of pyruvate dehydrogenase in the mousebird Colius striatus undergoing torpor

Phosphorylation status of pyruvate dehydrogenase in the mousebird Colius striatus undergoing torpor

Torpor‐responsive microRNAs in the heart of the Monito del monte, Dromiciops gliroides

Cool birds: first evidence of energy-saving nocturnal torpor in free-living common swifts Apus apus resting in their nests

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