BioProject

Numerous studies have established a critical role for BMP signaling in skeletal development. More...

Numerous studies have established a critical role for BMP signaling in skeletal development. In the developing axial skeleton, sequential SHH and BMP signals are required for specification of a chondrogenic fate in somitic tissue. A similar paradigm is thought to operate in the limb, but the signals involved are unclear. To investigate the nature of these signals we examined BMP action in mesenchymal populations derived from the early murine limb bud (~ E10.5). These populations exhibited a graded response to BMPs, in which early limb mesenchymal (EL) cells (from the distal hind limb) displayed an anti-chondrogenic response, whereas BMPs promoted chondrogenesis in older cell populations. To better understand the molecular basis of disparate BMP action in these various populations, gene expression profiling with Affymetrix microarrays was employed to identify BMP-regulated genes. These analyses showed that BMPs induced a distinct gene expression pattern in the EL cultures versus later mesenchymal limb populations (IM and LT). Overall design: Mouse embryos at gestational age E10.5 were collected and various portions of the limb were micro-dissected. These led to the generation of three populations of cells, early (EL) limb mesenchymal cells from the distal half of the hind limb, an intermediate (IM) population derived from the distal 1/3 of the fore limb, and a later (LT) population from the proximal 2/3 of the fore limb. Mesenchymal cells were isolated and cultured with and without BMP4 treatment. RNA was extracted from cultures at either Day 0,1 or 2, labelled and hybridized to Affymetrix 430 2.0 microarrays. For each time point, RNA was collected from two biological replicates for each treatment condition. Less...