Dehydration stress alters the mitogen-activated-protein kinase signaling and chaperone stress response in Xenopus laevis

Comp Biochem Physiol B Biochem Mol Biol. Aug-Sep 2020;246-247:110461. doi: 10.1016/j.cbpb.2020.110461. Epub 2020 Jun 1.

Abstract

In arid conditions, the African Clawed frog Xenopus laevis enters a state of estivation dormancy as an adaptive survival strategy. Under estivation, X. laevis experience severe dehydration stress as 25-35% of total body water is lost. Dehydration in X. laevis can lead to periods of hypoxia due to elevated blood viscosity that impedes tissue perfusion. To understand how X. laevis survives under such stress, we studied the regulation pattern of key mitogen-activated protein kinases (MAPK) and their downstream transcription factors, along with several heat shock proteins in the oxygen sensitive brain and heart tissue of X. laevis under dehydration stress. Our study revealed that the activation phosphorylation residues of MAPK including JNK and MSK and their downstream transcription factors c-Jun and ATF2 are significantly decreased in the heart under dehydration. Given that JNK, c-Jun, and ATF2 are known positive regulators of apoptosis, this regulatory pattern suggest that a state of pro-survival signals may be established in the dehydrated heart. In support of this, protein levels of HSP60, a pro-apoptotic mitochondrial chaperone, was also downregulated in the heart in response to dehydration stress. In the brain tissue, most proteins remain unchanged with the exception of the apoptosis regulating p53 transcription factor, which showed a significant decrease in its activating phosphorylation residue under dehydration. Overall, our study revealed that in the Xenopus brain and heart, a specific suppression pattern of MAPK, transcription factors, and HSP takes place to potentially establish a state of pro-survival under dehydration stress.

MeSH terms

  • Activating Transcription Factor 2 / metabolism
  • Animals
  • Brain / metabolism
  • Chaperonin 60 / metabolism*
  • Dehydration / metabolism*
  • Estivation / physiology
  • HSP70 Heat-Shock Proteins / metabolism
  • HSP90 Heat-Shock Proteins / metabolism
  • Heat-Shock Response / genetics
  • Heat-Shock Response / physiology
  • MAP Kinase Kinase 4 / metabolism
  • MAP Kinase Signaling System / genetics*
  • MAP Kinase Signaling System / physiology
  • Phosphorylation
  • Proto-Oncogene Proteins c-jun / metabolism
  • Ribosomal Protein S6 Kinases, 90-kDa / metabolism
  • Tumor Suppressor Protein p53 / metabolism*
  • Xenopus laevis / metabolism*

Substances

  • Activating Transcription Factor 2
  • Chaperonin 60
  • HSP70 Heat-Shock Proteins
  • HSP90 Heat-Shock Proteins
  • Proto-Oncogene Proteins c-jun
  • Tumor Suppressor Protein p53
  • Ribosomal Protein S6 Kinases, 90-kDa
  • mitogen and stress-activated protein kinase 1
  • MAP Kinase Kinase 4