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Proteins related to the human transcription factor Sp1 are characterized by the presence of a highly conserved zinc finger domain consisting of three C2H2 type zinc fingers. Here we describe two Xenopus laevis cDNAs, which encode novel Sp1-related C2H2 type zinc finger transcription factors named XSPR-1 and XSPR-2. Structurally, XSPR-1 and XSPR-2 are closely related to the murine Sp5, which interacts genetically with Brachyury (Dev. Biol. 227 (2000) 358). XSPR-1 and XSPR-2 are expressed in broad and dynamic patterns during early development. Starting at gastrulation, XSPR-1 transcripts are restricted to the non-involuting marginal zone, and, at later stages, to the neuroectoderm, forebrain, otic vesicles and the midbrain/hindbrain boundary. In contrast, XSPR-2 expression is found predominantly within the presumptive mesoderm during gastrulation. At tailbud and tadpole stages, XSPR-2 is expressed exclusively in the tip of the tail.
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12049774
???displayArticle.link???Mech Dev
Fig. 3. XSPR-1 and XSPR-2 expression during early embryogenesis as detected by whole-mount in situ hybridization. Antisense RNA probes used for in situ hybridization and stages of embryogenesis (Nieuwkoop and Faber, 1967) are shown on the right and on the left of each panel, respectively. (A,C,E,G) Vegetal view; (B,D,F,H) parasagittal section; (C,D) double staining in situ hybridization of Xbra (red) with XSPR-1 (purple); (D) parasagittal section of the embryo shown in (C); (G,H) double staining in situ hybridization of Xbra (red) with XSPR-2 (purple); (H) parasagittal section of the embryo shown in (G); (I) double staining in situ hybridization of Krox20 (red) with XSPR-1 (purple), anterior view; (J) anterior transversal section; (K) double staining in situ hybridization of En2 (red) with XSPR-1 (purple), anterior view; (L) lateral view of the head of a tadpoleembryo; (M) double staining in situ hybridization of Krox20 (red) with XSPR-2 (purple), dorso-anterior view; (N) XSPR-2, posterior transversal section; (O) double staining in situ hybridization of En2 (red) with XSPR-2 (purple), dorso-anterior view; (P) lateral view of a tadpoleembryo; (Q) transversal section at the level of the otic vesicle; (R) transversal section at the level of the midbrain/hindbrain boundary; (S) parasagittal section through the tail tip region. Abbreviations: aet, archenteron; bc, blastocoel; br, blastocoel roof; cnh, chordaneural hinge; end, endoderm; ep, epidermis; ev, eye vesicle; eym, endodermal yolk mass; fb, forebrain; lm, lateralmesoderm; mbh, midbrain/hindbrain boundary; mc, mesencephalon; nc, notochord; nec, neuroenteric canal; ov, otic vesicle; pw, posterior wall; rb, remnants of blastocoel; rc, rhombencephalon; rv, rhombencephalic ventricle; s, somites; sln, sensorial layer of neuroectoderm; sm, somitogenic mesoderm; vym, vegetal yolk mass.
sp5 (Sp5 transcription factor) gene expression in Xenopus laevis embryos, NF stage 32, as assayed by in situ hybridization. Lateral view: anteriorleft, dorsal up.
sp5l (Sp5 transcription factor-like) gene expression in Xenopus laevis embryos, NF stage 32, as assayed by in situ hybridization. Lateral view: anteriorleft, dorsal up.
Fig. 2. Expression of XSPR-1 and XSPR-2 during embryogenesis and in
adult tissues as detected by RT-PCR. The expression of XSPR-1 and XSPR-
2 was monitored by RT-PCR using histone H4 as an internal control at
various stages of Xenopus development (A) and in adult tissues and organs
(B) using primers specific for XSPR-1, XSPR-2 or histone H4.