engleski

Toll-like receptor 2 deficiency affects neuroplastin and P-type ATPases expression in mouse brain

Transmembrane proteins, neuroplastin (Np), and Toll-like receptor 2 (TLR2) are implicated in tuning the neuro-architecture. Np isoforms (Np55 and Np65) are related to synaptic plasticity and neuronal ion homeostasis by interactions with plasma membrane Ca2+ ATPases (PMCA). TLR2 is mainly expressed on microglia, but much broader cellular localization of TLR2 has been established, particularly during neurodevelopment. To test the hypothesis that TLR2 deficiency affects membrane dynamics, we analysed membrane protein phenotype in the brains of TLR2 knock-out (KO) mice. Cortical, cerebellar, and hippocampal tissue derived from male TLR2-KO and age-matched control (C) mice (N=36+36) underwent systematic biochemical profiling encompassing: analysis of Np55, Np65, PMCA, Na+/K+-ATPase (NKA) expression by Western blot (WB) ; transcriptional variations of selected genes by qPCR ; synaptic proteome by mass spectrometry (MS) ; activity of NKA and PMCA by spectrophotometry. MS analysis revealed astonishing differences in the synaptic proteome. Increased Np55, Np65, and NKA expression in cortex, cerebellum, and hippocampus was determined by WB in TLR2 vs. C. These findings were confirmed at a transcriptional level using qPCR. WB analysis of 4 PMCA isoforms showed that lack of TLR2 is associated with decreased expression of PMCA2 in cortex and cerebellum and increased in hippocampus. Changes in NKA and PMCA activity were also observed in TLR2 KO vs. C. Multiple-level analysis revealed that TLR2 deficiency leads to altered expression of proteins associated with synaptic plasticity and ion homeostasis. Observed proteomic changes are related to glutamatergic transmission, neuronal cytoskeleton organization, and mitochondrion energy metabolism. Further investigation may clarify previously undescribed roles of TLR2 in neuron-microglia interactions, synaptic connections arrangement, and neurotransmission.

neuroplastin ; toll-like receptor 2 ; synaptic transmission ; ion homeostasis ; immune system

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