Xenopus glucose transporter 1 (xGLUT1) is required for gastrulation movement in Xenopus laevis

Glucose transporters (GLUTs) are transmembrane proteins that play an essential role in sugar uptake and energy supply. Thirteen GLUT genes have been described and GLUT1 is the most abundantly expressed member of the family in animal tissues. Deficiencies in human GLUT1 are associated with many diseases, such as metabolic abnormalities, congenital brain defects and oncogenesis. It was suggested recently that Xenopus GLUT1 (xGLUT1) is upregulated by Activin/ Nodal signaling, although the developmental role of xGLUT1 remains unclear. Here, we investigated the expression pattern and function of xGLUT1 during Xenopus development. Whole-mount in situ hybridization analysis showed expression of xGLUT1 in the mesodermal region of Xenopus embryos, especially in the dorsal blastopore lip at the gastrula stage. From the neurula stage, it was expressed in the neural plate, eye field, cement gland and somites. Loss-of-function analyses using morpholino antisense oligonucleotides against xGLUT1 (xGLUT1MO) caused microcephaly and axis elongation error. This elongation defect of activin-treated animal caps occurred without downregulation of early mesodermal markers. Moreover, dorsal-marginal explant analysis revealed that cell movement was suppressed in dorsal marginal zones injected with xGLUT1MO. These findings implicate xGLUT1 as an important player during gastrulation cell movement in Xenopus.