ANG-1 TIE-2 and BMPR signalling defects are not seen in the nitrofen model of pulmonary hypertension and congenital diaphragmatic hernia.

BACKGROUND: Pulmonary hypertension (PH) is a lethal disease that is associated with characteristic histological abnormalities of the lung vasculature and defects of angiopoetin-1 (ANG-1), TIE-2 and bone morphogenetic protein receptor (BMPR)-related signalling. We hypothesized that if these signalling defects cause PH generically, they will be readily identifiable perinatally in congenital diaphragmatic hernia (CDH), where the typical pulmonary vascular changes are present before birth and are accompanied by PH after birth. METHODS: CDH (predominantly left-sided, LCDH) was created in Sprague-Dawley rat pups by e9.5 maternal nitrofen administration. Left lungs from normal and LCDH pups were compared at fetal and postnatal time points for ANG-1, TIE-2, phosphorylated-TIE-2, phosphorylated-SMAD1/5/8 and phosphorylated-ERK1/2 by immunoprecipitation and Western blotting of lung protein extracts and by immunohistochemistry on lung sections. RESULTS: In normal lung, pulmonary ANG-1 protein levels fall between fetal and postnatal life, while TIE-2 levels increase. Over the corresponding time period, LCDH lung retained normal expression of ANG-1, TIE-2, phosphorylated-TIE-2 and, downstream of BMPR, phosphorylated-SMAD1/5/8 and phosphorylated-p44/42. CONCLUSION: In PH and CDH defects of ANG-1/TIE-2/BMPR-related signalling are not essential for the lethal vasculopathy.

The heparanome and regulation of cell function: structures, functions and challenges.

The cell-extracellular matrix interface is a crowded space whose structure is dependent on macromolecular assemblies that are dynamic in time, molecular composition and location. Signals travel from one cell to another (or to the same cell) by the regulated assembly/disassembly of molecular complexes. These signals can evoke relatively simple biological responses such cell proliferation and migration, but once integrated, they guide cell fate in complex biological phenomena such as embryonic development and organism homeostasis. Heparan sulfate proteoglycans are ubiquitous components of this space and important actors of these processes in all tissue-organized life forms. A key feature of heparan sulfate is its size, 40 nm to 160 nm, which enables it to integrate self-assembling macromolecular structures over substantial length scales. What is the structure of heparan sulfate? Why do we think heparan sulfate is so important? How do we try to explain its activity? What do we know about its interactions? These questions together with a final look to the future are the "menu" of this review.

Neuropilins: a versatile partner of extracellular molecules that regulate development and disease.

Neuropilins are a vertebrate-specific family of membrane multidomain proteins. They are crucial for the embryonic development of neural and vascular systems, whereas in the adult organism they are implicated in many processes, such as angiogenesis and the immune response. Additionally, it has been shown that they are overexpressed in numerous types of tumours, which results in higher microvessel density and correlates with poor prognosis. Their functions have been linked to their binding partners: semaphorins/collapsins, vascular endothelial growth factors (VEGFs), fibroblast growth factors (FGFs), hepatocyte growth factor/scatter factor and heparin/heparan sulfate (HS). Multiplicity of ligands alongside complex formation with several membrane receptors makes neuropilins potential 'hub' proteins, which act as a scaffold for multimeric associations. This review focuses on the structural features of neuropilins that underpin their multiple molecular interactions and hence their function.