The Matricellular Protein R-Spondin 2 Promotes Midbrain Dopaminergic Neurogenesis and Differentiation

Summary: The development of midbrain dopaminergic (mDA) neurons is controlled by multiple morphogens and transcription factors. However, little is known about the role of extracellular matrix proteins in this process. Here we examined the function of roof plate-specific spondins (RSPO1-4) and the floor plate-specific, spondin 1 (SPON1). Only RSPO2 and SPON1 were expressed at high levels during mDA neurogenesis, and the receptor LGR5 was expressed by midbrain floor plate progenitors. Surprisingly, RSPO2, but not SPON1, specifically promoted the differentiation of mDA neuroblasts into mDA neurons in mouse primary cultures and embryonic stem cells (ESCs). In addition, RSPO2 was found to promote not only mDA differentiation, but also mDA neurogenesis in human ESCs. Our results thus uncover an unexpected function of the matricellular protein RSPO2 and suggest an application to improve mDA neurogenesis and differentiation in human stem cell preparations destined to cell replacement therapy or drug discovery for Parkinson disease. : Gyllborg and colleagues report on the function of the matricellular protein R-Spondin 2 (RSPO2) in dopaminergic neuron development. RSPO2 is dynamically expressed during midbrain development and promotes the dopaminergic differentiation of mouse and human neuroblasts. Furthermore, they show that RSPO2 induced dopaminergic neurogenesis in human stem cell cultures, suggesting a possible application of RSPO2 in cell replacement strategies for Parkinson disease. Keywords: extracellular matrix, RSPO2, progenitors, dopaminergic neurons, differentiation, neurogenesis, human embryonic stem cells, Wnt, cell replacement, Parkinson diseas