Weeks DL and Melton DA (1987), A maternal mRNA localized to the vegetal hemisp...

XB-ART-27835

Cell December 4, 1987; 51 (5): 861-7.

A maternal mRNA localized to the vegetal hemisphere in Xenopus eggs codes for a growth factor related to TGF-beta.

Weeks DL , Melton DA .

Abstract
We report that Vg1, a maternal mRNA localized to the vegetal hemisphere of frog eggs, encodes a member of the transforming growth factor-beta (TGF-beta) family of proteins. Furthermore, we show that Vg1 mRNA is distributed to presumptive endodermal cells after fertilization. Previous studies had shown that the vegetal end of a frog egg produces a signal that induces the overlying animal pole cells to form mesodermal tissue. More recently it has been shown that fibroblast growth factor (FGF) and TGF-beta can participate in the induction of muscle. Together, these results lead us to propose that the formation of mesoderm during frog development is specified by the products of localized maternal mRNAs, including Vg1.

PubMed ID: 3479264
Article link: Cell

Species referenced: Xenopus laevis
Genes referenced: dspp gdf1 h4c1 h4c4 tgfb1

Article Images: [+] show captions

	Figure 1. Diagram and Sequence of the Vgl Transcript (A) Diagram of the Vgi transcript. Restriction sites are as follows: P Pstl; B, BarnHI; Bg, Bglll; Bt, BstEll; K, Kpnl. The open reading frame of the Vgl transcript is shown below, with the region believed to direct the protein to the endoplasmic reticulum marked as a signal sequence, and the region of homology to TGF-3 is indicated. (B) Nucleotide sequence of the Vgl transcript including some upstream sequence. The start site of transcrip tion is marked “0” and is accurate to within 2 bases.
	Figure 2. Mapping the 5’ End of the Vgl Transcript by Primer Extension M. pWi322 Hpall markers; lane 1, extension products of primer plus oocyte RNA; lane 2, extension products of primer alone; lane 3, primer alone. The extension of Vgl RNA is indicated by the arrow.
	Figure 3. Comparison of Vgl Protein with Selected Members of the TGF-b Gene Family The probable processing sites are enclosed in boxes, the conserved cysteine residues are marked by asterisks, and the possible glycosylation site conserved between Vgl and dpp is indicated by the bar. In each case only the carboxyl end of a much larger protein is shown.
	Figure 4. In Situ Hybridization of Vgl Probe to Oocytes, Eggs, and Cleavage Embryos Paraffin sections of an albino oocyte (A), an unfertilized egg (B and D), and an early blastula embryo (C)were hybridized with 32P-labeled Vgl (A, B, and C) or 32P-labeled histone H4 (D) antisense RNA probes. The hybridization grains (white) show the location of Vgl or histone mRNAs. Autoradiographic exposure was for 10 days (A and B), 2 weeks (C), or 2 days(D). In each case, the animal (ectodermal) pole is at the top and the vegetal (endodermal) pole is at the bottom. GV is the oocyte’s nucleus or germinal vesicle.