Differential expression of non-muscle myosin heavy chain genes during Xenopus embryogenesis.
Class II non-muscle myosins are implicated in diverse biological processes such as cytokinesis, cellularization, cell shape changes and gastrulation. Two distinct non-muscle myosin heavy chain genes have been reported in all vertebrates: non-muscle myosin heavy chain-A (NMHC-A) and -B (NMHC-B). We report here the isolation of the Xenopus homolog of NMHC-A and present a comparative analysis of the developmental and spatial expression patterns of NMHC-A and the previously isolated NMHC-B to address the role of NMHCs in Xenopus development. A 7.5 kb NMHC-A mRNA is present, maternally in unfertilized eggs and throughout embryogenesis, as well as in all adult tissues examined. An additional 8.3 kb zygotic transcript for NMHC-A is also detected, but only during embryonic stages. Whole mount in situ hybridization with tailbud stage embryos shows that NMHC-A mRNA is predominantly expressed in the epidermis, whereas NMHC-B mRNA is expressed in the somites, brain, eyes and branchial arches. Interestingly, the expression of NMHC-B in developing somites is gradually restricted to the center of each somite as differentiation proceeds. DAPI nuclear staining demonstrated that NMHC-B mRNA is colocalized with the nuclei or perinuclear area. In animal cap experiments, treatment with activin A or ectopic expression of Xbra and an activated form of Xlim1 markedly up-regulates NMHC-B as well as muscle actin mRNAs and slightly down-regulates NMHC-A mRNA, consistent with NMHC-B expression in the somitic muscle and NMHC-A expression in the epidermis.
Bhatia-Dey
N
N
Laboratory of Molecular Cardiology, National Heart Lung and Blood Institute, Bethesda, MD, USA.
Taira
M
M
Conti
M A
MA
Nooruddin
H
H
Adelstein
R S
RS
D028341:Activins; D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005326:Fetal Proteins; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology; D017403:In Situ Hybridization; D007265:Inhibins / Q000494:pharmacology; D060850:LIM-Homeodomain Proteins; D018995:Myosin Heavy Chains / Q000096:biosynthesis* / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology; D009928:Organ Specificity; D020033:Protein Isoforms / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020825:T-Box Domain Proteins; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism; D000098908:Brachyury Protein
D028341:Activins; D004268:DNA-Binding Proteins; D005326:Fetal Proteins; D018398:Homeodomain Proteins; D007265:Inhibins; D060850:LIM-Homeodomain Proteins; D018995:Myosin Heavy Chains; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D020825:T-Box Domain Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; D000098908:Brachyury Protein; C083056:LHX3 protein, Xenopus; C543964:Lhx1 protein, Xenopus