Retrograde Degenerative Signaling Mediated by the p75 Neurotrophin Receptor Requires p150^Glued Deacetylation by Axonal HDAC1

During development, neurons undergo apoptosis if they do not receive adequate trophic support from tissues they innervate or when detrimental factors activate the p75 neurotrophin receptor (p75NTR) at their axon ends. Trophic factor deprivation (TFD) or activation of p75NTR in distal axons results in a retrograde degenerative signal. However, the nature of this signal and the regulation of its transport are poorly understood. Here, we identify p75NTR intracellular domain (ICD) and histone deacetylase 1 (HDAC1) as part of a retrograde pro-apoptotic signal generated in response to TFD or ligand binding to p75NTR in sympathetic neurons. We report an unconventional function of HDAC1 in retrograde transport of a degenerative signal and its constitutive presence in sympathetic axons. HDAC1 deacetylates dynactin subunit p150^Glued, which enhances its interaction with dynein. These findings define p75NTR ICD as a retrograde degenerative signal and reveal p150^Glued deacetylation as a unique mechanism regulating axonal transport. Retrograde degenerative signaling is suggested to regulate neuronal survival and degeneration. Pathak et al. identify a retrograde degenerative signal involving the intracellular domain of p75 neurotrophin receptor and histone deacetylase, HDAC1, in sympathetic neurons. HDAC1 regulates retrograde axonal transport by deacetylating dynactin subunit p150^Glued, enhancing its binding to dynein.