Deregulated Transcription and Proteostasis in Adult mapt Knockout Mouse

Int J Mol Sci. 2023 Mar 31;24(7):6559. doi: 10.3390/ijms24076559.

Abstract

Transcriptomics and phosphoproteomics were carried out in the cerebral cortex of B6.Cg-Mapttm1(EGFP)Klt (tau knockout: tau-KO) and wild-type (WT) 12 month-old mice to learn about the effects of tau ablation. Compared with WT mice, tau-KO mice displayed reduced anxiety-like behavior and lower fear expression induced by aversive conditioning, whereas recognition memory remained unaltered. Cortical transcriptomic analysis revealed 69 downregulated and 105 upregulated genes in tau-KO mice, corresponding to synaptic structures, neuron cytoskeleton and transport, and extracellular matrix components. RT-qPCR validated increased mRNA levels of col6a4, gabrq, gad1, grm5, grip2, map2, rab8a, tubb3, wnt16, and an absence of map1a in tau-KO mice compared with WT mice. A few proteins were assessed with Western blotting to compare mRNA expression with corresponding protein levels. Map1a mRNA and protein levels decreased. However, β-tubulin III and GAD1 protein levels were reduced in tau-KO mice. Cortical phosphoproteomics revealed 121 hypophosphorylated and 98 hyperphosphorylated proteins in tau-KO mice. Deregulated phosphoproteins were categorized into cytoskeletal (n = 45) and membrane proteins, including proteins of the synapses and vesicles, myelin proteins, and proteins linked to membrane transport and ion channels (n = 84), proteins related to DNA and RNA metabolism (n = 36), proteins connected to the ubiquitin-proteasome system (UPS) (n = 7), proteins with kinase or phosphatase activity (n = 21), and 22 other proteins related to variegated pathways such as metabolic pathways, growth factors, or mitochondrial function or structure. The present observations reveal a complex altered brain transcriptome and phosphoproteome in tau-KO mice with only mild behavioral alterations.

Keywords: cytoskeleton; phosphoproteomics; synapse; tau-KO; transcriptomics.

MeSH terms

  • Animals
  • Cerebral Cortex / metabolism
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Mice
  • Mice, Knockout
  • Nerve Tissue Proteins / metabolism
  • Neurons / metabolism
  • Proteostasis*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • tau Proteins* / genetics
  • tau Proteins* / metabolism

Substances

  • tau Proteins
  • RNA, Messenger
  • Grip2 protein, mouse
  • Nerve Tissue Proteins
  • Intracellular Signaling Peptides and Proteins
  • Mapt protein, mouse