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Cytosolic phospholipase A2 regulation in the hibernating thirteen-lined ground squirrel


Cytosolic calcium-dependent phospholipase A2 (cPLA2) has multiple roles including production of arachidonic acid (a key player in cellular signaling pathways) and membrane remodeling. Additionally, since catabolism of arachidonic acid generates free radicals, the enzyme is also implicated in ischemic injury to mammalian organs. Regulation of cPLA2 could be important in the suppression and prioritization of cellular pathways in animals that undergo reversible transitions into hypometabolic states. The present study examines the responses and regulation of cPLA2 in skeletal muscle and liver of hibernating thirteen-lined ground squirrels, Spermophilus tridecemlineatus. cPLA2 activity decreased significantly by 43% in liver during hibernation, compared with euthermic controls, and Km values for arachidonoyl thio-PC substrate fell in both organs during hibernation to 61% in liver and 28% in muscle of the corresponding euthermic value. To determine whether these responses were due to a change in the phosphorylation state of the enzyme, Western blotting was employed using antibodies recognizing phospho-Ser505 on α-cPLA2. The amount of phosphorylated α-cPLA2 in hibernator liver was just 38% of the value in euthermic liver. Furthermore, incubation of liver extracts under conditions that enhanced protein phosphatase action caused a greater reduction in the detectable amount of phospho-Ser505 enzyme content in euthermic, versus hibernator, extracts. The data are consistent with a suppression of cPLA2 function during torpor via enzyme dephosphorylation, an action that may contribute to the well-developed ischemia tolerance and lack of oxidative damage found in hibernating species over cycles of torpor and arousal.


cPLA2 :

cytosolic calcium-dependent phospholipase A2


5,5′-dithio-bis(2-nitrobenzoic acid)


mitogen-activated protein kinase




phenylmethylsulfonyl fluoride


  1. 1.

    Katsuki, H. and Okuda, S. Arachidonic acid as a neurotoxic and neurotrophic substance. Prog. Neurobiol.. 46 (1995) 607–636.

    PubMed  Article  CAS  Google Scholar 

  2. 2.

    Asai, K., Hirabayashi, T., Houjou, T., Uozumi, N., Taguchi, R. and Shimizu, T. Human group IVC phospholipase A2 (PLA). J. Biol. Chem. 278 (2003) 8809–8814.

    PubMed  Article  CAS  Google Scholar 

  3. 3.

    Brown, W. J., Chambers, K. and Doody, A. Phospholipase A2 (PLA2) enzymes in membrane trafficking: mediators of membrane shape and function. Traffic 4 (2003) 214–221.

    PubMed  CAS  Article  Google Scholar 

  4. 4.

    Han, C., Demetris, A. J., Michalopoulos, G., Shelhamer, J. H. and Wu, T. 85-kDa PLA2 plays a critical role in PPAR-mediated gene transcription in human hepatoma cells. Am. J. Physiol. 282 (2002) G586–G597.

    CAS  Google Scholar 

  5. 5.

    Dessen, A. Structure and mechanism of human cytosolic phospholipase A2. Biochim. Biophys. Acta 1488 (2000) 40–47.

    PubMed  CAS  Google Scholar 

  6. 6.

    Hirabayashi, T. and Shimizu, T. Location and regulation of cytosolic phospholipase A2. Biochim. Biophys. Acta 1488 (2000) 124–138.

    PubMed  CAS  Google Scholar 

  7. 7.

    Balsinde, J., Balboa, M. A., Insel, P. A. and Dennis, E. A. Regulation and inhibition of phospholipase A2. Annu. Rev. Pharmacol. Toxicol. 39 (1999) 175–189.

    PubMed  Article  CAS  Google Scholar 

  8. 8.

    Shimizu, T., Ohto, T. and Kita, Y. Cytosolic phospholipase A2: biochemical properties and physiological roles. IUBMB Life 58 (2006) 328–333.

    PubMed  CAS  Article  Google Scholar 

  9. 9.

    Zhu, X., Sano, H., Kim, K. P., Sano, A., Boetticher, E., Munoz, N. M., Cho, W. and Leff, A. R. Role of mitogen-activated protein kinase-mediated cytosolic phospholipase A2 activation in arachidonic acid metabolism in human eosinophils. J. Immunol. 167 (2001) 461–468.

    PubMed  CAS  Google Scholar 

  10. 10.

    Zhou, H., Das, S. and Murthy, K.S. Erk1/2-and p38 MAP kinase-dependent phosphorylation and activation of PLA2 by m3 and m2 receptors. Am. J. Physiol. 284 (2003) G472–G480.

    CAS  Google Scholar 

  11. 11.

    Muralikrishna Adibhatla, R. and Hatcher, J.F. Phospholipase A2, reactive oxygen species, and lipid peroxidation in cerebral ischemia. Free Radic. Biol. Med. 40 (2006) 376–387.

    PubMed  Article  CAS  Google Scholar 

  12. 12.

    Hermes-Lima, M., Storey, J.M. and Storey, K.B. Antioxidant defenses and animal adaptation to oxygen availability during environmental stress. in: Cell and Molecular Responses to Stress (Storey, K.B. and Storey, J.M.), Elsevier Press, Amsterdam, 2001, 263–287.

    Google Scholar 

  13. 13.

    Storey K. B. and Storey J. M. Mammalian hibernation: biochemical adaptation and gene expression. in: Functional Metabolism: Regulation and Adaptation (Storey, K.B., Ed.), Wiley-Liss, Hoboken, 2004, 443–471.

    Google Scholar 

  14. 14.

    Storey, K.B. and Storey, J.M. Metabolic rate depression in animals: transcriptional and translational controls. Biol. Rev. Camb. Philos. Soc. 79 (2004) 207–233.

    PubMed  Article  Google Scholar 

  15. 15.

    Brustovetsky, N. N., Mayesky, E. I., Grishina, E. V., Gogvadze, V. G. and Amerkhanov, Z. G. Regulation of the rate of respiration and oxidative phosphorylation in liver mitochondria from hibernating ground squirrels, Citellus undulatus. Comp. Biochem. Physiol. B 94 (1989) 537–541.

    PubMed  Article  CAS  Google Scholar 

  16. 16.

    Brustovetsky, N. N., Egorova, M. V. and Mayevsky, E. I. Regulation of oxidative activity and ΔΨ of liver mitochondria of active and hibernating gophers. The role of phospholipase A2. Comp. Biochem. Physiol. B 102 (1992) 635–638.

    PubMed  Article  CAS  Google Scholar 

  17. 17.

    Brooks, S.P.J. A program for analyzing enzyme rate data obtained from a microplate reader. BioTechniques 17 (1994) 1155–1161.

    Google Scholar 

  18. 18.

    Brooks, S.P.J. A simple computer program with statistical tests for the analysis of enzyme kinetics. BioTechniques 13 (1992) 906–911.

    PubMed  CAS  Google Scholar 

  19. 19.

    Morin, P. and Storey, K. B. Cloning and expression of hypoxia-inducible factor 1α from the hibernating ground squirrel, Spermophilus tridecemlineatus. Biochim. Biophys. Acta 1729 (2005) 32–40.

    PubMed  CAS  Google Scholar 

  20. 20.

    Mamady, H. and Storey, K. B. Up-regulation of the endoplasmic reticulum molecular chaperone GRP78 during hibernation in thirteen-lined ground squirrels. Mol. Cell. Biochem. 292 (2006) 89–98.

    PubMed  Article  CAS  Google Scholar 

  21. 21.

    Drew, K.L., Toien, O., Rivera, P.M., Smith, M.A., Perry, G. and Rice, M.E. Role of the antioxidant ascorbate in hibernation and warming from hibernation. Comp. Biochem. Physiol. C 133 (2002) 483–492.

    CAS  Google Scholar 

  22. 22.

    Buzadzic, B., Spasic, M. Saicic, Z.S., Radojicic, R., Petrovic, V.M. and Halliwell, B. Antioxidant defenses in the ground squirrel Citellus citellus. 2. The effect of hibernation, Free Radic. Biol. Med. 9 (1990) 407–413.

    PubMed  Article  CAS  Google Scholar 

  23. 23.

    Barja de Quiroga, G. Brown fat thermogenesis and exercise: two examples of physiological oxidative stress? Free Radic. Biol. Med. 13 (1992) 325–340.

    Article  Google Scholar 

  24. 24.

    Eddy, S.F., McNally, J.D. and Storey, K.B. Up-regulation of a thioredoxin peroxidase-like protein, proliferation associated gene, in hibernating bats. Arch. Biochem. Biophys. 435 (2005) 101–111.

    Article  CAS  Google Scholar 

  25. 25.

    Clark, J. D., Schievella, A. R., Nalefski, E. A. and Lin, L. L. Cytosolic phospholipase A2. J. Lipid Med. Cell Signal. 12 (1995) 83–117.

    Article  CAS  Google Scholar 

  26. 26.

    Chakraborti, S. Phospholipase A2 isoforms: a perspective. Cell. Signal. 15 (2003) 637–665.

    PubMed  Article  CAS  Google Scholar 

  27. 27.

    Bailleux, A., Wendum, D., Audubert, F., Jouniau, A., Koumanov, K., Trugnan, G. and Masliah, J. Cytosolic phospholipase A2/p11 interaction controls arachidonic acid release as a function of epithelial cell confluence. Biochem. J. 378 (2004) 307–315.

    PubMed  Article  CAS  Google Scholar 

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Correspondence to Kenneth B. Storey.

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Woods, A.K., Storey, K.B. Cytosolic phospholipase A2 regulation in the hibernating thirteen-lined ground squirrel. Cell Mol Biol Lett 12, 621 (2007).

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Key words

  • Metabolic rate depression
  • Signaling
  • Arachidonic acid production
  • Reversible phosphorylation
  • Spermophilus tridecemlineatus