A truncated bone morphogenetic protein receptor affects dorsal-ventral patterning in the early Xenopus embryo.

TLDR

Bone morphogenetic proteins (BMPs), members of the TGF‑β superfamily, are involved in bone formation and early developmental regulation. The authors cloned a cDNA encoding a BMP‑2/4‑binding serine/threonine kinase receptor to investigate BMP function in Xenopus laevis embryogenesis. They blocked BMP signaling in embryos by expressing a dominant‑negative mutant of the receptor lacking the kinase domain. Expression of this mutant in ventral blastomeres respecified them to dorsal mesoderm, producing a secondary body axis and demonstrating that BMP‑2/4 are required for dorsal‑ventral specification and that ventral fate requires induction.

Abstract

Bone morphogenetic proteins (BMPs), which are members of the transforming growth factor beta (TGF-beta) superfamily, have been implicated in bone formation and the regulation of early development. To better understand the roles of BMPs in Xenopus laevis embryogenesis, we have cloned a cDNA coding for a serine/threonine kinase receptor that binds BMP-2 and BMP-4. To analyze its function, we attempted to block the BMP signaling pathway in Xenopus embryos by using a dominant-negative mutant of the BMP receptor. When the mutant receptor lacking the putative serine/threonine kinase domain was expressed in ventral blastomeres of Xenopus embryos, these blastomeres were respecified to dorsal mesoderm, eventually resulting in the formation of a secondary body axis. These findings suggest that endogenous BMP-2 and BMP-4 are involved in the dorsal-ventral specification in the embryo and that ventral fate requires induction rather than resulting from an absence of dorsal specification.