ABSTRACT: During cell stress, the transcription and translation of immediate early genes are prioritized, while most other mRNAs are stored away in stress granules or degraded in P-bodies. TIA-1 is an mRNA binding protein that needs to translocate from the nucleus to seed the formation of stress granules in the cytoplasm. Since other stress granule components such as TDP-43, FUS, ATXN2, SMN, MAPT, HNRNPA2B1 and HNRNPA1 are crucial for the motor neuron diseases ALS / SMA and for the frontotemporal dementia FTD, here we studied mouse nervous tissue to identify mRNAs with selective dependence on Tia1 deletion. Transcriptome profiling with oligonucleotide microarrays in comparison of spinal cord and cerebellum, together with independent validation in quantitative reverse transcriptase PCR and immunoblots demonstrated several strong and consistent dysregulations. In agreement with previously reported TIA1 knock-down effects, cell cycle and apoptosis regulators were affected markedly with expression changes up to 2-fold, exhibiting increased levels for Cdkn1a, Ccnf, and Tprkb versus decreased levels for Bid and Inca1 transcripts. Novel and surprisingly strong expression alterations were detected for fat storage and membrane trafficking factors, with prominent above 3-fold upregulations of Plin4, Wdfy1, Tbc1d24, and Pnpla2, versus a 0.5 -fold?? downregulation of Cntn4 transcript, encoding an axonal membrane adhesion factor with established haploinsufficiency. In comparison subtle effects on the RNA processing machinery included up to 1.2-fold upregulations of Dcp1b and Tial1. The effect on lipid dynamics factors is noteworthy, since also the gene deletion of Tardbp (encoding TDP-43) and Atxn2 led to fat metabolism phenotypes in mouse. In conclusion, genetic ablation of the stress granule nucleator TIA-1 has a novel major effect on mRNAs encoding lipid homeostasis factors in the brain. Factorial design comparing Tia1 knock-out mice with wild type littermates in four different tissues (midbrain, cerebellum, liver, spinal cord) and 2 different ages.
