Involvement of an inner nuclear membrane protein, Nemp1, in Xenopus neural development through an interaction with the chromatin protein BAF.
To clarify the molecular mechanisms of neural development in vertebrates, we analyzed a novel gene, termed nemp1 (nuclear envelope integral membrane protein 1), which is expressed in the Xenopus anterior neuroectoderm at the neurula stage. Nemp1 has a putative signal peptide and five transmembrane domains, but does not have any other known domains. We show that Nemp1 is localized to the inner nuclear membrane (INM) with its evolutionarily conserved C-terminal region facing the nucleoplasm. Both overexpression and knockdown of Nemp1 in Xenopus embryos reduced the expression of early eye marker genes, rax, tbx3, and pax6, and later resulted mainly in severe eye defects at the tailbud stage. In contrast, the expression of a forebrain/midbrain marker, otx2, and a pan-neural marker, sox2, was largely unaffected. Deletion analysis of Nemp1 showed that nuclear envelope-localization of the C-terminal region is necessary for its eye-reducing activity. Furthermore, nemp1 is coexpressed with baf (barrier-to-autointegration factor) in the eye anlagen, and that Nemp1 interacts with BAF through the BAF-binding site in the C-terminal region and this site is required for Nemp1 activity. These data suggest that Nemp1 is involved in the expression of eye marker genes by functioning at the INM at least partly through BAF.
Mamada
Hiroshi
H
Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Takahashi
Noriyuki
N
Taira
Masanori
M
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005124:Eye Abnormalities / Q000235:genetics; D055785:Gene Knockdown Techniques; D006801:Humans; D017403:In Situ Hybridization; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D055495:Neurogenesis; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000033:anatomy & histology / Q000196:embryology
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; C539763:Nemp1 protein, Xenopus; D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense; D029867:Xenopus Proteins