2021.04.20
Phosphorylation of GAP-43 T172 is a molecular marker of growing axons in a wide range of mammals including primates
(Mol Brain.2021 Apr 8;14(1):66. doi: 10.1186/s13041-021-00755-0.)
Okada M1,2,3, Kawagoe Y3, Sato Y3,11, Nozumi M3, Ishikawa Y3,4, Tamada A3,12, Yamazaki H5, Sekino Y6, Kanemura Y7, Shinmyo Y8, Kawasaki H8, Kaneko N9, Sawamoto K9,10, Fujii Y1,2, Igarashi M3.
1Department of Neurosurgery, Brain Research Institute, School of Medicine and Graduate School of Medical/Dental Sciences, Niigata University.
2Medical and Dental Hospital, School of Medicine and Graduate School of Medical/Dental Sciences, Niigata University.
3Departments of Neurochemistry and Molecular Cell Biology, School of Medicine and Graduate School of Medical/Dental Sciences, Niigata University.
4Department of Orthopedic Surgery, School of Medicine and Graduate School of Medical/Dental Sciences, Niigata University.
5Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine.
6Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo.
7Division of Regenerative Medicine, Department of Biomedical Research and Innovation, Institute for Clinical Research, National Hospital Organization Osaka National Hospital, Osaka.
8Department of Medical Neuroscience, Graduate School of Medical Sciences, Kanazawa University.
9Department of Developmental and Regenerative Neurobiology, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences.
10Division of Neural Development and Regeneration, National Institute for Physiological Sciences.
11Present Address: Department of Chemistry, Faculty of Science, Hokkaido University.
12Present Address: Department of iPS Cell Applied Medicine, Faculty of Medicine, Kansai Medical University.
Abstract
GAP-43 is a vertebrate neuron-specific protein and that is strongly related to axon growth and regeneration; thus, this protein has been utilized as a classical molecular marker of these events and growth cones. Although GAP-43 was biochemically characterized more than a quarter century ago, how this protein is related to these events is still not clear. Recently, we identified many phosphorylation sites in the growth cone membrane proteins of rodent brains. Two phosphorylation sites of GAP-43, S96 and T172, were found within the top 10 hit sites among all proteins. S96 has already been characterized (Kawasaki et al., 2018), and here, phosphorylation of T172 was characterized. In vitro (cultured neurons) and in vivo, an antibody specific to phosphorylated T172 (pT172 antibody) specifically recognized cultured growth cones and growing axons in developing mouse neurons, respectively. Immunoblotting showed that pT172 antigens were more rapidly downregulated throughout development than those of pS96 antibody. From the primary structure, this phosphorylation site was predicted to be conserved in a wide range of animals including primates. In the developing marmoset brainstem and in differentiated neurons derived from human induced pluripotent stem cells, immunoreactivity with pT172 antibody revealed patterns similar to those in mice. pT172 antibody also labeled regenerating axons following sciatic nerve injury. Taken together, the T172 residue is widely conserved in a wide range of mammals including primates, and pT172 is a new candidate molecular marker for growing axons.
