title: Positive regulation of myoblast differentiation by medaka Neu3b sialidase through gangliosides desialylation.
abstract: Sialidase Neu3b is an unique enzyme conserved in medaka and tilapia, but not in mammals. Previous study revealed that medaka Neu3b is localized at cytosol and is a ganglioside-specific sialidase. Neu3b functions, however, have not been understood, while Neu3a sialidase, which is widely conserved from human to fish, is known as a regulator of neurite formation. Here, we investigated the biological function of Neu3b for C2C12 myoblast cell differentiation. Bioinformatics analysis using genome browser revealed the presence of neu3b gene in some orders of fish species such as Beloniformes, Perciformes and Cyprinodontiformes. With the treatment of 2% horse serum, Neu3b-overexpression accelerated myoblast cell differentiation to myotubes accompanied with up-regulation of myogenesis biomarkers mRNA, myod and myog. Neu3b altered ganglioside composition in C2C12 cells results showing a decrease in GM2, and the increase of Lac-Cer, while desialylation of glycoproteins were not detected. Contrary to cell differentiation, Neu3b cell proliferation was suppressed in normal growth medium. To understand the mechanism of the alteration of cell differentiation and proliferation, phosphorylation of signal molecules in EGFR/ERK pathway was investigated. Neu3b induced a decline in phosphorylation of ERK and EGFR. Surprisingly, immuno-blot and real-time PCR analysis revealed that down-regulation of egfr gene could be involved in the acceleration of cell differentiation by Neu3b. These results suggested that Neu3b sialidase is a positive regulator for myoblast differentiation, similar with mammalian cytosolic sialidase Neu2.
authors.affiliation: Faculty of Fisheries, Kagoshima University, Kagoshima, Kagoshima, Japan; The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan. Electronic address: shiozaki@fish.kagoshima-u.ac.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shiozaki
authors.affiliation: Faculty of Fisheries, Kagoshima University, Kagoshima, Kagoshima, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Harasaki
authors.affiliation: Faculty of Fisheries, Kagoshima University, Kagoshima, Kagoshima, Japan.
authors.forename: Midori
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: Faculty of Fisheries, Kagoshima University, Kagoshima, Kagoshima, Japan.
authors.forename: Ayana
authors.initials: A
authors.lastname: Yoshinaga
authors.affiliation: Faculty of Fisheries, Kagoshima University, Kagoshima, Kagoshima, Japan.
authors.forename: Sena
authors.initials: S
authors.lastname: Ryuzono
authors.affiliation: Faculty of Fisheries, Kagoshima University, Kagoshima, Kagoshima, Japan; The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Petros Kingstone
authors.initials: PK
authors.lastname: Chigwechokha
authors.affiliation: Faculty of Fisheries, Kagoshima University, Kagoshima, Kagoshima, Japan; The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Komatsu
authors.affiliation: Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai, Miyagi, Japan.
authors.forename: Taeko
authors.initials: T
authors.lastname: Miyagi
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D005732:Gangliosides / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology*; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D009439:Neuraminidase / Q000378:metabolism*; D009990:Oryzias
chemical_list: D005732:Gangliosides; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid
keywords: Epidermal growth factor receptor; Ganglioside; Medaka; Myogenesis; Sialidase