Xmab21l3 mediates dorsoventral patterning in Xenopus laevis

Abstract

Specification of the dorsoventral (DV) axis is critical for the subsequent differentiation of regional fate in the primary germ layers of the vertebrate embryo. We have identified a novel factor that is essential for dorsal development in embryos of the frog Xenopus laevis. Misexpression of Xenopus mab21-like 3 (Xmab21l3) dorsalizes gastrula-stage mesoderm and neurula-stage ectoderm, while morpholino-mediated knockdown of Xmab21l3 inhibits dorsal differentiation of these embryonic germ layers. Xmab21l3 is a member of a chordate-specific subclass of a recently characterized gene family, all members of which contain a conserved, but as yet ill-defined, Mab21 domain. Our studies suggest that Xmab21l3 functions to repress ventralizing activity in the early vertebrate embryo, via BMP/Smad and Ras/ERK signaling.

mab21-l3 regulates cell fate specification of multiciliate cells and ionocytes

“…As mab21-l3 expression is positively regulated by foxi1 (ref. 24), there is a feedback relationship between foxi1 and mab21-l3 (see Fig. 9d).…”

“…During our screen identifying genes that show a characteristic expression pattern in the embryonic epithelium, we found that an evolutionarily conserved gene, mab21-l3, showed a salt-andpepper pattern of expression (see below). Mab21 was first identified in Caenorhabditis elegans, and three orthologous genes, mab21-like 1 (mab21-l1), mab21-like 2 (mab21-l2) and mab21-l3, have been identified in vertebrates 23,24 . Among these three genes, mab21-l3 has been poorly studied.…”

“…Among these three genes, mab21-l3 has been poorly studied. Xenopus mab21-l3 was recently shown to regulate dorsal development 24 , but its detailed expression pattern and role in epidermal development have not been examined. We first analysed the spatial expression pattern of Xenopus mab21-l3 by whole-mount in situ hybridization ( Supplementary Fig.…”

“…The expression was first detected in the presumptive ectoderm in the animal region at the early gastrula stage (stage 10.5), and became restricted to the ventral ectoderm with a spotted pattern at the late gastrula stage (stage 12/13). At neurula and tailbud stages (stage [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], mab21-l3 is expressed in the epidermis with a salt-and-pepper pattern.…”

Structural and biochemical characterization of the cell fate determining nucleotidyltransferase fold protein MAB21L1

“…Whereas MAB21 is required for pattern formation of the male tail in nematodes, MAB21 is sufficient and required for development of the dorso-ventral axis in vertebrates103334. MAB21 proteins act downstream of the TGF-β signaling pathway by antagonizing the effect of BMP4 in Xenopus embryo ventralization and in C. elegans MAB21 is negatively regulated by cet-1 (vertebrate BMP4)22.…”