Inflammation is an important event in ischemic injury. These immune responses begin with the expression of pro-inflammatory genes modulating transcription factors, such as nuclear factor-κB (NF-κB), activator protein-1 (AP-1), and signal transducers and activator of transcription-1 (STAT-1). The 70-kDa heat shock protein (Hsp70) can both induce and arrest inflammatory reactions and lead to improved neurological outcome in experimental brain injury and ischemia. Since Hsp70 are induced under heat stress, we investigated the link between Hsp70 neuroprotection and phosphorylation of inhibitor of κB (IκB), c-Jun N-terminal kinases (JNK) and p38 through co-immunoprecipitation and enzyme-linked immunosorbent assay (ELISA) assay. Transcription factors and pro-inflammatory genes were quantified by immunoblotting, electrophoretic-mobility shift assay and reverse transcription-polymerase chain reaction assays. The results showed that heat stress led to Hsp70 overexpression which rendered neuroprotection after ischemia-like injury. Overexpression Hsp70 also interrupts the phosphorylation of IκB, JNK and p38 and blunts DNA binding of their transcription factors (NF-κB, AP-1 and STAT-1), effectively downregulating the expression of pro-inflammatory genes in heat-pretreated astrocytes. Taken together, these results suggest that overexpression of Hsp70 may protect against brain ischemia via an anti-inflammatory mechanism by interrupting the phosphorylation of upstream of transcription factors.
|Number of pages||9|
|Publication status||Published - 2015 Feb 2|
Bibliographical noteFunding Information:
This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korea Government (MEST) ( NRF-2014R1A2A2A01006556 ) which was awarded to JEL. This work was also sponsored by a grant from National Institutes of Health ( NS40516 ) and the Veteran’s Merit Award to MY (I01 BX000589), as well as an American Heart Association Western States Affiliate Postdoctoral Fellowship ( 13POST14810019 ) to JYK. Grants to MY and JYK were administered by the Northern California Institute for Research and Education , and supported by resources provided by the Veterans Affairs Medical Center, San Francisco, California.
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