SLAM-sequencing of BDNF on human derived IPSC lower motor neurons
Axonal degeneration underlies neuromuscular disorders and neuropathies. Dysregulation of neurotrophic factors, such as brain-derived neurotrophic factor (BDNF), in the peripheral nervous system has long been established to exacerbate axonopathy. However, the molecular programs controlled by BDNF which facilitate axonal regeneration and transport are not well-understood. Here, we unravel the transcriptomic and phosphorylation landscape shaped by BDNF in human iPSC-derived motor neurons. Using SLAM-Seq, we reveal BDNF stimulation increases global transcription rate in motor neurons and governs  gene regulatory networks that converge with those engaged during axonal repair/outgrowth. Phosphoproteomic analyses demonstrate BDNF remodels the phosphorylation landscape of cytoskeletal-binding proteins, especially of structural microtubule-associated proteins. Importantly, the localized axonal-specific activation of ERK1/2 is necessary for BDNF to enhance axonal transport of neurotrophin-containing signaling endosomes and to potentiate axonal regeneration after axotomy. Collectively, this work unveils a novel molecular paradigm that positions BDNF as a core regulator of transcriptional and phosphorylation programs driving axonal regeneration and transport in human motor neurons