Phosphorylation of the zebrafish M6Ab at serine 263 contributes to filopodium formation in PC12 cells and neurite outgrowth in zebrafish embryos.
BACKGROUND
Mammalian M6A, a member of the proteolipid protein (PLP/DM20) family expressed in neurons, was first isolated by expression cloning with a monoclonal antibody. Overexpression of M6A was shown to induce filopodium formation in neuronal cells; however, the underlying mechanism of is largely unknown. Possibly due to gene duplication, there are two M6A paralogs, M6Aa and M6Ab, in the zebrafish genome. In the present study, we used the zebrafish as a model system to investigate the role of zebrafish M6Ab in filopodium formation in PC12 cells and neurite outgrowth in zebrafish embryos.


RESULTS
We demonstrated that zebrafish M6Ab promoted extensive filopodium formation in NGF-treated PC12 cells, which is similar to the function of mammalian M6A. Phosphorylation at serine 263 of zebrafish M6Ab contributed to this induction. Transfection of the S263A mutant protein greatly reduced filopodium formation in PC12 cells. In zebrafish embryos, only S263D could induce neurite outgrowth.


CONCLUSIONS
Our results reveal that the phosphorylation status of zebrafish M6Ab at serine 263 is critical for its role in regulating filopodium formation and neurite outgrowth.
Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
Kai-Yun
KY
Huang
Gen-Der
GD
Chen
Chia-Hsiung
CH
Cheng
Kuan-Ya
KY
Liao
Chin-Chun
CC
Hung
Geen-Dong
GD
Chang
Pung-Pung
PP
Hwang
Shu-Yu
SY
Lin
Ming-Chieh
MC
Tsai
Kay-Hooi
KH
Khoo
Ming-Ting
MT
Lee
Chang-Jen
CJ
Huang
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D002522:Chlorocebus aethiops; D004625:Embryo, Nonmammalian / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000378:metabolism*; D016716:PC12 Cells; D010766:Phosphorylation / Q000187:drug effects; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D012694:Serine / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D006023:Glycoproteins; D008562:Membrane Glycoproteins; D029961:Zebrafish Proteins; C570201:gpm6ab protein, zebrafish; D012694:Serine; D020932:Nerve Growth Factor; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2