RESUMO
Local protein synthesis in axons and dendrites underpins synaptic plasticity. However, the composition of the protein synthesis machinery in distal neuronal processes and the mechanisms for its activity-driven deployment to local translation sites remain unclear. Here, we employed cryo-electron tomography, volume electron microscopy, and live-cell imaging to identify Ribosome-Associated Vesicles (RAVs) as a dynamic platform for moving ribosomes to distal processes. Stimulation via chemically-induced long-term potentiation causes RAV accumulation in distal sites to drive local translation. We also demonstrate activity-driven changes in RAV generation and dynamics in vivo, identifying tubular ER shaping proteins in RAV biogenesis. Together, our work identifies a mechanism for ribosomal delivery to distal sites in neurons to promote activity-dependent local translation.
RESUMO
Understanding the communication of individual neurons necessitates precise control of neural activity. Photothermal modulation is a remote and non-genetic technique to control neural activity with high spatiotemporal resolution. The local heat release by photothermally active nanomaterial will change the membrane properties of the interfaced neurons during light illumination. Recently, it is demonstrated that the two-dimensional Ti3 C2 Tx MXene is an outstanding candidate to photothermally excite neurons with low incident energy. However, the safety of using Ti3 C2 Tx for neural modulation is unknown. Here, the biosafety of Ti3 C2 Tx -based photothermal modulation is thoroughly investigated, including assessments of plasma membrane integrity, mitochondrial stress, and oxidative stress. It is demonstrated that culturing neurons on 25 µg cm-2 Ti3 C2 Tx films and illuminating them with laser pulses (635 nm) with different incident energies (2-10 µJ per pulse) and different pulse frequencies (1 pulse, 1 Hz, and 10 Hz) neither damage the cell membrane, induce cellular stress, nor generate oxidative stress. The threshold energy to cause damage (i.e., 14 µJ per pulse) exceeded the incident energy for neural excitation (<10 µJ per pulse). This multi-assay safety evaluation provides crucial insights for guiding the establishment of light conditions and protocols in the clinical translation of photothermal modulation.
RESUMO
OBJECTIVES: In rheumatoid arthritis (RA) patients, TGF-ß exerts a singular effect on lymphocytes, macrophages, and polymorphonuclear leukocytes. Moreover, evidences indicate that TGF-ß1 stimulation affects the expression levels of TGF-ß receptors. Therefore, we analysed in different leukocyte subpopulations, whether the mRNA abundance of TGFBR2 splice variants might be related to RA. METHODS: We isolated different leukocyte subpopulations from peripheral blood from 9 healthy control volunteers and 9 RA patients, matched by gender and age (cohort 1), and 8 additional RA patients (cohort 2). Then we quantified, by RT-qPCR, the mRNA relative abundance of TGFBR2 splice variants (namely TGFBR2A and TGFBR2B) in PMNs, and PBMCs (monocytes and non-monocytes). We first checked whether the TGFBR2-splice variant mRNA profile could be associated with any particular blood cell type both, in healthy control volunteers and in RA patients. In addition, PBMC and PMN mRNA levels were correlated, using Spearman's rank-order correlation test, with clinical and biochemical determinations of RA patients. RESULTS: We have shown that TGFBR2 exhibits an alternative splicing pattern in different subpopulations of human leucocytes from healthy controls, and the lack of it in the same cell type from RA samples. Furthermore, our study yields initial evidence that TGFBR2 mRNA expression levels in monocytes might mirror RA disease activity. CONCLUSIONS: mRNA abundance of TGFBR2 splice variants in monocytes shows changes linked to RA disease activity.
