Heterozygous mutation of NF-B innate immune response transcription factor Relish increases survival following traumatic brain injury in Drosophila

ABSTRACT: Traumatic brain injury (TBI) pathologies are caused by primary and secondary injuries. Primary injuries result from physical damage to the brain, and secondary injuries arise from cellular responses to primary injuries. A characteristic cellular response is sustained activation of inflammatory pathways commonly mediated by NF-B transcription factors. Using a Drosophila melanogaster TBI model, we previously found that the main proximal transcriptional response to primary injuries is triggered by activation of Toll and Imd innate immune response pathways that engage NF-B factors Dif and Relish (Rel), respectively. Here, we monitor the abundance of Rel protein by mass spectrometry (MS) and observe that Rel increases in fly heads at 4-8 h after TBI. To investigate the necessity of Rel for secondary injuries, we generated a null allele, Reldel, by CRISPR/Cas9 editing. Heterozygous but not homozygous Reldel mutation reduced mortality at 24 h after TBI and increased the lifespan of injured flies. Additionally, the effect of heterozygous Reldel mutation on mortality was modulated by genetic background and diet. To identify genes that facilitate effects of heterozygous Reldel mutation on TBI outcomes, we compared genome-wide mRNA expression profiles of uninjured and injured +/+, +/Reldel, and Reldel/Reldel flies at 4 h following TBI. Only a few genes changed expression more than two-fold in +/Reldel flies relative to +/+ and Reldel/Reldel flies, and they were not canonical innate immune response genes. Therefore, Rel is necessary for TBI-induced secondary injuries but in complex ways involving Rel gene dose, genetic background, diet, and possibly small changes in expression of innate immune response genes.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Drosophila Melanogaster (fruit Fly)

TISSUE(S): Brain

SUBMITTER: Edna Angelica Trujillo  

LAB HEAD: Joshua J. Coon

PROVIDER: PXD021869 | Pride | 2020-12-04

REPOSITORIES: Pride