Ricerc@Sapienza

Alteration of RNA binding proteins (RBPs) has been linked to Amyotrophic Lateral Sclerosis (ALS). We have recently identified HuD/ELAVL4 as a novel neural RBP involved in FUS-linked and sporadic ALS (De Santis et al., 2017; De Santis et al., 2019). New preliminary evidence from multiple FUS models revealed that: a) altered HuD levels are possibly due to competition between mutant FUS and FMRP for HuD 3'UTR binding; b) as a consequence, levels of HuD targets NRN1 and GAP43 are also increased; c) FUS mutant motoneurons display aberrant axon branching and growth upon injury. NRN1 and GAP43 are HuD-regulated genes that might underlie this phenotype. It has been recently shown that co-cultures of iPSC-derived motor neurons and myotubes from patients with FUS-ALS display endplate maturation defects due to intrinsic FUS toxicity in both motor neurons and myotubes (Picchiarelli et al., 2019).
Here we aim at establishing a link between the altered formation of neuromuscular junctions and the molecular circuitry involving mutant FUS and HuD. This project is based on a relevant in vitro model, consisting of engineered human iPSCs, raised in the laboratory of Prof. Rosa. We will, in particular, take advantage of the possibility to convert iPSCs into disease-relevant cell types to establish co-cultures of motoneurons and skeletal muscle cells in microfluidics devices. The participation of Prof. Bozzoni will be instrumental for the analysis of skeletal muscle cells from iPSCs. This multidisciplinary project will greatly benefit from the expertise of Prof. Scopigno in optical imaging techniques and in particular coherent Raman microscopy, as a new tool to real-time, label-free in-vivo imaging of neuromuscular junction. Overall, we expect from this project insights into the contribution of the motoneuron to altered formation of the neuromuscular junction, as a therapeutic target in FUS ALS.