FIGURE 1 The BTB/POZ zinc- finger protein Zbtb14 promotes induction of posterior neural tissue and suppresses epidermal differentiation. (a) Structure of Xenopus laevis, Xenopus tropicalis and human Zbtb14 proteins. BTB/POZ domain, Broad- complex, Tramtrack and Bric- a- brac/Poxvirus and Zinc- finger domain. X. laevis zbtb14 encodes a 452- amino- acid protein containing a BTB/POZ domain with 98% and 97% amino acid identity to the X. tropicalis and human domains, respectively, and five C2H2- type zinc- finger domains with over 93% and 86% amino acid identity to the X. tropicalis and human domains, respectively. (b) Overexpression of Zbtb14 promotes neural induction and reduces epidermal differentiation in ectodermal explants. zbtb14-GR mRNA (125 pg and 250 pg) was injected into the animal region of 4- cell- stage embryos. Ectodermal explants were isolated from 12 embryos at the blastula stage, treated with DEX to activate Zbtb14, and cultured until late neurula stage (stage 20). Expression of marker genes was determined by semi- quantitative RT- PCR. Emb and –RT indicate whole- embryo RNA processed in, respectively, the presence or absence of reverse transcriptase. histone H4 was used as a loading control. (c–j) Zbtb14 expands the expression region of the neural plate markers sox2 and ncam (arrows) at the expense of epidermal keratin expression (arrowheads). Together with β-galactosidase (β-gal) mRNA, zbtb14-GR (125 pg) mRNA was injected unilaterally into both dorsal and ventral animal blastomeres of 8- cell- stage embryos. The injected side of the embryo is indicated by brackets. Expression of sox2, ncam and epidermal keratin analyzed by whole- mount in situ hybridization is shown in purple and β- Gal is stained in red. The top six panels (c–h) show dorsal views with posterior to the top. The bottom panels (i and j) show diagonal views with posterior to the right. (k–r) Zbtb14 expands the expression of the posterior marker cad2 (cdx2) and the spinal cord marker hoxb9 (m and p, respectively; black arrows), and the anterior limits of hoxb9 expression shift anteriorly with respect to the uninjected side of the embryo (r; white arrowheads). By contrast, Zbtb14 severely reduces the expression region of both the fore- and midbrain marker otx2 and the mid- and hindbrain marker en2 on the injected side (k and l, respectively; black arrowheads). Interestingly, the hindbrain marker krox20 shows both reduced and anteriorly shifted expression with respect to the uninjected side of the embryo (black and orange arrowheads in o and n/q, respectively). (q) and (r) show enlarged views of n and p, respectively. Dotted lines in (q) and (r) indicate the median line of embryos.
Image published in: Takebayashi-Suzuki K et al. (2018)
Copyright © 2018. Image reproduced with permission of the Publisher, John Wiley & Sons.
| Gene | Synonyms | Species | Stage(s) | Tissue |
|---|---|---|---|---|
| sox2.S | anop3, LOC108718087, mcops3, Sox-2, XLSOX-2, Xsox-2, XSox2 | X. laevis | Throughout NF stage 20 | neural plate |
| ncam1.L | n-cam, n-cam-1, ncam, ncam1-a, ncam1-b | X. laevis | Throughout NF stage 20 | neural plate |
| krt12.4.L | ck81, cytok, cytokeratin, E-keratin, epi-keratin, epidermal keratin, Epidermis-specific keratin, EpiK, epiker, EpK, epK, K81, xK81, xk81a, xk81a1 | X. laevis | Throughout NF stage 20 | epidermis non-neural ectoderm |
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