Effects of moderate and deep hypothermia on RNA-binding proteins RBM3 and CIRP expressions in murine hippocampal brain slices

Brain Res. 2013 Apr 4;1504:74-84. doi: 10.1016/j.brainres.2013.01.041. Epub 2013 Feb 8.

Abstract

Therapeutic hypothermia has emerged as an effective neuroprotective therapy for cardiac arrest survivors. There are a number of purported mechanisms for therapeutic hypothermia, but the exact mechanism still remains to be elucidated. Although hypothermia generally down-regulates protein synthesis and metabolism in mammalian cells, a small subset of homologous (>70%) cold-shock proteins (RNA-binding motif protein 3, RBM3 and cold-inducible RNA-binding protein, CIRP) are induced under these conditions. In addition, RBM3 up-regulation in neuronal cells has recently been implicated in hypothermia-induced neuroprotection. Therefore, we compared the effects of moderate (33.5°C) and deep (17°C) hypothermia with normothermia (37°C) on the regulation of RBM3 and CIRP expressions in murine organotypic hippocampal slice cultures (OHSC), hippocampal neuronal cells (HT-22), and microglia cells (BV-2). Moderate hypothermia resulted in significant up-regulation of both RBM3 and CIRP mRNA in murine OHSC, but deep hyporthermia did not. RBM3 protein regulation was also significantly up-regulated by 33.5°C, but no significant up-regulation of CIRP protein was observed in the OHSC. Additionally, OHSC exposed to 17°C for 24h were positive for Propidium Iodide (PI) immunostaining, indicating the onset of cell death. Similarly, RBM3 gene expression in a HT-22 neuronal cells mono-culture and direct co-culture of HT-22 neuronal cells with BV-2 microglia cells were also up-regulated at 33.5°C but only in the co-culture at 17°C. No significant up-regulation of RBM3 nor CIRP gene expression were observed in a BV-2 mono-culture at either temperature. We observed that RBM3 mRNA and protein expressions in murine OHSC, as well as in mono-culture of HT-22 neuronal cells and direct co-culture of HT-22 neuronal cells with BV-2 microglia cells were significantly up-regulated by exposure to moderate hypothermia. These findings further support the implication of RBM3 as a potential effector for hypothermia-induced neuroprotection.

MeSH terms

  • Animals
  • Cell Line
  • Coculture Techniques
  • Hippocampus / metabolism*
  • Hypothermia, Induced*
  • Immunoblotting
  • Mice
  • Mice, Inbred C57BL
  • Microglia / metabolism
  • Neurons / metabolism
  • Organ Culture Techniques
  • RNA-Binding Proteins / biosynthesis*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Up-Regulation

Substances

  • Cirbp protein, mouse
  • RNA-Binding Proteins
  • Rbm3 protein, mouse