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- Title
The CCAAT/enhancer-binding protein δ (C/EBP-δ) transcription factor is heat inducible in the cold-adapted antarctic fish Trematomus bernacchii.
- Authors
Sleadd, Isaac; Buckley, Bradley
- Abstract
Notothenioids dominate the Antarctic ichthyofauna, which for millions of years has evolved in a thermally stable environment near the freezing point of seawater. These species are extreme stenotherms and at least some have lost the ability to up-regulate heat shock proteins during exposure to thermal stress. A recent cDNA microarray study revealed the capacity to mount a broad-scale genomic response to heat in the common notothenioid Trematomus bernacchii. Two of the heat-sensitive genes identified were of the CCAAT/enhancer-binding protein (C/EBP) family of transcription factors. One of these, C/EBP-δ, mediates inflammatory and pro-apoptotic processes, though it is best known for functioning as a brake on cell division. Because apoptosis and cell-cycle arrest are two understudied facets of the cellular stress response, we used western blotting to examine C/EBP-δ expression in T. bernacchii under normal and heat-stressed conditions. A highly tissue-specific pattern of constitutive levels of C/EBP-δ was detected in field-acclimated individuals. Highest levels were found in white muscle followed by spleen, brain, and gill. C/EBP-δ was not detected in heart or liver. Individuals acclimated for 1 month at 4.0 °C possessed more C/EBP-δ in their white muscle compared with field-acclimated fish. Acute heat stress of 2.0 or 4.0 °C caused a transient increase in white muscle C/EBP-δ after 6 h when compared with controls (−1.0 ± 0.5 °C). This up-regulation appears to be reversible upon return to non-stressful conditions. We posit that in unstressed T. bernacchii, C/EBP-δ performs housekeeping functions and that it mediates inflammation, apoptosis, and/or cell-cycle arrest in response to sub-lethal heat stress.
- Subjects
CCAAT enhancer binding proteins; TRANSCRIPTION factors; TREMATOMUS bernacchii; FREEZING points; PHYSIOLOGICAL effects of heat; THERMAL stresses; ANTISENSE DNA; APOPTOSIS
- Publication
Polar Biology, 2013, Vol 36, Issue 3, p335
- ISSN
0722-4060
- Publication type
Article
- DOI
10.1007/s00300-012-1262-8