Rabbit Anti-Human WNT9A (C-terminal) Polyclonal antibody

Systemic sclerosis ( SSc) is a complex human disorder characterized by progressive skin fibrosis. To better understand the molecular basis of dermal fibrosis in SSc, we analyzed microarray gene expression in skin of the Tight- skin ( Tsk) mouse, an animal model where skin fibrosis is caused by an in- frame duplication in fibrillin- 1 ( Fbn- 1). Tsk skin showed increased mRNA levels of several genes involved in Wnt signaling, including Wnt2, Wnt9a, Wnt10b and Wnt11; Dapper homolog antagonist of beta-catenin ( DACT1) and DACT2; Wnt- induced secreted protein 2; and secreted frizzled- related protein ( SFRP) 2 and SFRP4. RNase protection and northern blot confirmed microarray results. Furthermore, Wnt3a markedly stimulated matrix assembly of microfibrillar proteins, including Fbn- 1, by cultured fibroblasts, suggesting that Wnts contribute to increased microfibrillar matrices in Tsk skin. Further analysis showed that SFRP4 expression is specifically increased in tissues expressing Tsk- Fbn- 1, such as skeletal muscle and skin. The increase in SFRP4 mRNA in Tsk skin started 2 weeks after birth, following the increase in Wnt2 mRNA that occurred at birth. This suggests that SFRP4 may modulate Wnt functions in Tsk skin fibrosis. Lesional skin from SSc patients also showed large increases in SFRP4 mRNA and protein levels in the deep dermis compared to healthy skin, suggesting that the Wnt pathway might regulate skin fibrosis in SSc.

In the mouse blastocyst, some cells of the inner cell mass (ICM) develop into primitive endoderm (PE) at the surface, while deeper cells form the epiblast. It remained unclear whether the position of cells determines their fate, such that gene expression is adjusted to cell position, or if cells are pre-specified at random positions and then sort. We have tracked and characterised dynamics of all ICM cells from the early to late blastocyst stage. Time-lapse microscopy in H2B-EGFP embryos shows that a large proportion of ICM cells change position between the surface and deeper compartments. Most of this cell movement depends on actin and is associated with cell protrusions. We also find that while most cells are precursors for only one lineage, some give rise to both, indicating that lineage segregation is not complete in the early ICM. Finally, changing the expression levels of the PE marker Gata6 reveals that it is required in surface cells but not sufficient for the re-positioning of deeper cells. We provide evidence that Wnt9A, known to be expressed in the surface ICM, facilitates re-positioning of Gata6-expressing cells. Combining these experimental results with computer modelling suggests that PE formation involves both cell sorting movements and position-dependent induction. (C) 2009 Elsevier Inc. All rights reserved.