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PPARα-Mediated Positive-Feedback Loop Contributes to Cold Exposure Memory.

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Cells can adapt to cold by "memorizing" brief cold exposure, enhancing survival through a PPARα-D6D-AA pathway. This adaptation involves maintaining ATP levels and requires linoleic acid or arachidonic acid.

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Area of Science:

  • Cell biology
  • Environmental adaptation
  • Metabolic pathways

Background:

  • Environmental changes like temperature shifts signal animals to prepare for harsher conditions.
  • HEK293A cells under starvation conditions exhibit enhanced survival after short cold exposure.
  • This phenomenon is termed 'cold adaptation'.

Purpose of the Study:

  • To investigate the cellular mechanisms underlying
  • cold adaptation
  • in response to brief cold temperature exposure.
  • To identify key molecular players and pathways involved in this adaptive response.

Main Methods:

  • Culturing HEK293A cells under starvation and cold exposure (15°C).
  • Assessing cell survival rates and ATP levels.
  • Utilizing fatty acid oxidation inhibitors (etomoxir), linoleic acid (LA), arachidonic acid (AA), PPARα agonists/antagonists, and D6D inhibitors.

Main Results:

  • Cold-exposed cells maintained higher ATP levels and survival rates.
  • Cold adaptation required linoleic acid (LA) and Δ-6-desaturase (D6D) activity.
  • Arachidonic acid (AA), a PPARα agonist, rescued cold adaptation even with D6D inhibition.
  • Cold exposure increased PPARα and D6D levels, dependent on PPARα and D6D activity.
  • Cold exposure inhibited PPARα degradation via the ubiquitin proteasome system.
  • Starvation enhanced PPARα activity by inhibiting mTORC1.

Conclusions:

  • A novel PPARα-D6D-AA axis mediates cellular
  • cold adaptation
  • via a positive-feedback mechanism.
  • This adaptation involves preventing PPARα degradation and enhancing its activity.
  • This innate mechanism may enhance cellular resilience against extreme cold.