The RNA-binding protein fragile X-related 1 regulates somite formation in Xenopus laevis.
Fragile X-related 1 protein (FXR1P) is a member of a small family of RNA-binding proteins that includes the Fragile X mental retardation 1 protein (FMR1P) and the Fragile X-related 2 protein (FXR2P). These proteins are thought to transport mRNA and to control their translation. While FMR1P is highly expressed in neurons, substantial levels of FXR1P are found in striated muscles and heart, which are devoid of FMRP and FXR2P. However, little is known about the functions of FXR1P. We have isolated cDNAs for Xenopus Fxr1 and found that two specific splice variants are conserved in evolution. Knockdown of xFxr1p in Xenopus had highly muscle-specific effects, normal MyoD expression being disrupted, somitic myotomal cell rotation and segmentation being inhibited, and dermatome formation being abnormal. Consistent with the absence of the long muscle-specific xFxr1p isoform during early somite formation, these effects could be rescued by both the long and short mRNA variants. Microarray analyses showed that xFxr1p depletion affected the expression of 129 known genes of which 50% were implicated in muscle and nervous system formation. These studies shed significant new light on Fxr1p function(s).
Huot
Marc-Etienne
ME
Unité de recherche en génétique humaine et moléculaire, CHUQ-St-François d'Assise, Québec, Québec G1L 3L5, Canada.
Bisson
Nicolas
N
Davidovic
Laetitia
L
Mazroui
Rachid
R
Labelle
Yves
Y
Moss
Tom
T
Khandjian
Edouard W
EW
D020413:3' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001757:Blastomeres / Q000378:metabolism; D002970:Cleavage Stage, Ovum / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000378:metabolism / Q000502:physiology*; D014644:Genetic Variation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000196:embryology; D017570:MyoD Protein / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D016415:Sequence Alignment; D019170:Somites / Q000378:metabolism* / Q000502:physiology; D029867:Xenopus Proteins / Q000378:metabolism / Q000502:physiology*
D020413:3' Untranslated Regions; D051860:Fragile X Messenger Ribonucleoprotein 1; D017570:MyoD Protein; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029867:Xenopus Proteins; C505711:FXR1 protein, Xenopus; C497686:Fmr1 protein, Xenopus