Dataset Information

HSF1 is involved in suppressing A1 phenotype conversion of astrocytes following spinal cord injury in rats.

ABSTRACT:

Background

Two activation states of reactive astrocytes termed A1 and A2 subtypes emerge at the lesion sites following spinal cord injury (SCI). A1 astrocytes are known to be neurotoxic that participate in neuropathogenesis, whereas A2 astrocytes have been assigned the neuroprotective activity. Heat shock transcription factor 1 (HSF1) plays roles in protecting cells from stress-induced apoptosis and in controlling inflammatory activation. It is unknown whether HSF1 is involved in suppressing the conversion of A1 astrocytes following SCI.

Methods

A contusion model of the rat spinal cord was established, and the correlations between HSF1 expression and onset of A1 and A2 astrocytes were assayed by Western blot and immunohistochemistry. 17-AAG, the agonist of HSF1, was employed to treat the primary cultured astrocytes following a challenge by an A1-astrocyte-conditioned medium (ACM) containing 3 ng/ml of IL-1α, 30 ng/ml of TNF-α, and 400 ng/ml of C1q for induction of the A1 subtype. The effects of 17-AAG on the phenotype conversion of astrocytes, as well as underlying signal pathways, were examined by Western blot or immunohistochemistry.

Results

The protein levels of HSF1 were significantly increased at 4 days and 7 days following rat SCI, showing colocalization with astrocytes. Meanwhile, C3-positive A1 astrocytes were observed to accumulate at lesion sites with a peak at 1 day and 4 days. Distinctively, the S100A10-positive A2 subtype reached its peak at 4 days and 7 days. Incubation of the primary astrocytes with ACM markedly induced the conversion of the A1 phenotype, whereas an addition of 17-AAG significantly suppressed such inducible effects without conversion of the A2 subtype. Activation of HSF1 remarkably inhibited the activities of MAPKs and NFκB, which was responsible for the regulation of C3 expression. Administration of 17-AAG at the lesion sites of rats was able to reduce the accumulation of A1 astrocytes.

Conclusion

Collectively, these data reveal a novel mechanism of astrocyte phenotype conversion following SCI, and HSF1 plays key roles in suppressing excessive increase of neurotoxic A1 astrocytes.

SUBMITTER: Li L

PROVIDER: S-EPMC8444373 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Spinal cord injury (SCI) is a destructive disease that incurs huge personal and social costs, and there is no effective treatment. Although the pathogenesis and treatment mechanism of SCI has always been a strong scientific focus, the pathogenesis of SCI is still under investigation. AIM:To determine the key genes based on the modularization of in-depth analysis, in order to identify the repair mechanism of astrocytes and non-astrocytes in SCI. METHODS:Firstly, the differences between injured and non-injured spinal cord of astrocyte (HA), injured and non-injured spinal cord of non-astrocyte (FLOW), injured spinal cord of non-injured astrocyte (HA) and non-injured spinal cord of non-astrocyte (FLOW), and non-injured spinal cord of astrocyte (HA) and non-astrocyte (FLOW) were analyzed. The total number of differentially expressed genes was obtained by merging the four groups of differential results. Secondly, the genes were co-expressed and clustered. Then, the enrichment of GO function and KEGG pathway of module genes was analyzed. Finally, non-coding RNA, transcription factors and drugs that regulate module genes were predicted using hypergeometric tests. RESULTS:In summary, we obtained 19 expression modules involving 5216 differentially expressed genes. Among them, miR-494, XIST and other genes were differentially expressed in SCI patients, and played an active regulatory role in dysfunction module, and these genes were recognized as the driving genes of SCI. Enrichment results showed that module genes were significantly involved in the biological processes of inflammation, oxidation and apoptosis. Signal pathways such as NF-kappa B/A20, AMPK and MAPK were significantly regulated. In addition, non-coding RNA pivot (including miR-136-5p and let-7d-5p, etc.) and transcription factor pivot (including NFKB1, MYC, etc.) were identified as significant regulatory dysfunction modules. CONCLUSION:Overall, this study uncovered a co-expression network of key genes involved in astrocyte and non-astrocyte regulation in SCI. These findings helped to reveal the core dysfunction modules, potential regulatory factors and driving genes of the disease, and to improve our understanding of its pathogenesis.

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