Early phosphorylation of MARCKS at Ser25 in migrating precursor cells and differentiating peripheral neurons

MARCKS is a ubiquitous actin-binding protein, with special functions in the development of the central nervous system. We have previously described a neuronal-specific isoform, phosphorylated at serine 25 (S25p-MARCKS), which is present very early during neuronal differentiation in the chick retina. However, very little is known about MARCKS expression or functions in the peripheral nervous system (PNS). In the present work, we analyzed migrating PNS precursor cells in the chick embryo, particularly those originating from the neural crest, and found that they all express a high amount of MARCKS and that a subpopulation of them also contained S25p-MARCKS from early developmental stages. MARCKS protein was also found in dorsal root and trigeminal ganglia during embryo development. Not only is the protein present in these structures but it is also phosphorylated in differentiating neurons with a maximal signal on the ganglion periphery, where neurogenesis is occurring. In conclusion, MARCKS is present and phosphorylated at early stages during the differentiation of PNS cells and precursors, indicating that it might also be important for the differentiation of these tissues.