The pathological loss of nuclear TDP-43 is a hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), leading to extensive alterations in RNA metabolism and a broad number of neuronal transcripts. However, the key effectors linking TDP-43 dysfunction to synaptic defects remain unclear. In this study, using Drosophila and human iPSC-derived motoneurons, we identify Rab4 as a direct and conserved target of TDP-43, whose expression is necessary and sufficient to recover synaptic vesicle recycling, neuromuscular junction growth, and locomotor function in TDP-43-deficient motoneurons. Moreover, Rab4 activity promotes the presynaptic recruitment of futsch/MAP1B, a microtubule-associated protein also regulated by TDP-43, which autonomously supports synaptic growth and vesicle turnover. Together, these findings define a TDP-43/Rab4/futsch/MAP1B regulatory axis that couples endosomal dynamics to cytoskeletal assembly. Furthermore, this functionally coherent module provides a mechanistic basis for understanding how synaptic vulnerability is amplified in disease and offers a framework to identify key compensatory targets capable of sustaining neuronal function in the absence of TDP-43.

Beta-hemoglobinopathies such as beta-thalassemia and sickle cell disease are severe genetic blood disorders affecting the beta globin chain of haemoglobin A (α2β2). Activation of delta globin, the non-alpha globin of HbA2 (α2δ2), could represent a possible approach to improve the clinical severity of these pathologies. Notably, the therapeutic potential of delta globin has been demonstrated in previous studies using a mouse model of beta-thalassemia and sickle cell disease. The present study evaluated delta globin gene activation by small molecules in erythroid cells isolated from transgenic murine foetal liver. A screening of 119 molecules, selected for their potential in drug repurposing, was performed without prior selection based on specific pathways of interest. Three candidates—Nexturastat, Stattic and Palbociclib—were found to have high efficacy on delta globin expression. Palbociclib also proved effective in increasing gamma globin expression. All of these compounds have pharmacokinetic profiles that are beneficial for clinical application, providing potential inducer agents of HbA2 that could have therapeutic effects in the treatment of beta-hemoglobinopathies.