HSPG-Deficient Zebrafish Uncovers Dental Aspect of Multiple Osteochondromas

Multiple Osteochondromas (MO; previously known as multiple hereditary exostosis) is an autosomal dominant genetic condition that is characterized by the formation of cartilaginous bone tumours (osteochondromas) at multiple sites in the skeleton, secondary bursa formation and impingement of nerves, tendons and vessels, bone curving, and short stature. MO is also known to be associated with arthritis, general pain, scarring and occasional malignant transformation of osteochondroma into secondary peripheral chondrosarcoma. MO patients present additional complains but the relevance of those in relation to the syndromal background needs validation. Mutations in two enzymes that are required during heparan sulphate synthesis (EXT1 or EXT2) are known to cause MO. Previously, we have used zebrafish which harbour mutations in ext2 as a model for MO and shown that ext2−/− fish have skeletal defects that resemble those seen in osteochondromas. Here we analyse dental defects present in ext2−/− fish. Histological analysis reveals that ext2−/− fish have very severe defects associated with the formation and the morphology of teeth. At 5 days post fertilization 100% of ext2−/− fish have a single tooth at the end of the 5th pharyngeal arch, whereas wild-type fish develop three teeth, located in the middle of the pharyngeal arch. ext2−/− teeth have abnormal morphology (they were shorter and thicker than in the WT) and patchy ossification at the tooth base. Deformities such as split crowns and enamel lesions were found in 20% of ext2+/− adults. The tooth morphology in ext2−/− was partially rescued by FGF8 administered locally (bead implants). Our findings from zebrafish model were validated in a dental survey that was conducted with assistance of the MHE Research Foundation. The presence of the malformed and/or displaced teeth with abnormal enamel was declared by half of the respondents indicating that MO might indeed be also associated with dental problems

Estrogen Receptor Agonists and Antagonists in the Yeast Estrogen Bioassay

Cell-based bioassays can be used to predict the eventual biological activity of a substance on a living organism. In vitro reporter gene bioassays are based on recombinant vertebrate cell lines or yeast strains and especially the latter are easy-to-handle, cheap, and fast. Moreover, yeast cells do not express estrogen, androgen, progesterone or glucocorticoid receptors, and are thus powerful tools in the development of specific reporter gene systems that are devoid of crosstalk from other hormone pathways. This chapter describes our experience with an in-house developed RIKILT yeast estrogen bioassay for testing estrogen receptor agonists and antagonists, focusing on the applicability of the latter

Regulation of Zebrafish Skeletogenesis by ext2/dackel and papst1/pinscher

Mutations in human Exostosin genes (EXTs) confer a disease called Hereditary Multiple Exostoses (HME) that affects 1 in 50,000 among the general population. Patients with HME have a short stature and develop osteochondromas during childhood. Here we show that two zebrafish mutants, dackel (dak) and pinscher (pic), have cartilage defects that strongly resemble those seen in HME patients. We have previously determined that dak encodes zebrafish Ext2. Positional cloning of pic reveals that it encodes a sulphate transporter required for sulphation of glycans (Papst1). We show that although both dak and pic are required during cartilage morphogenesis, they are dispensable for chondrocyte and perichondral cell differentiation. They are also required for hypertrophic chondrocyte differentiation and osteoblast differentiation. Transplantation analysis indicates that dak−/− cells are usually rescued by neighbouring wild-type chondrocytes. In contrast, pic−/− chondrocytes always act autonomously and can disrupt the morphology of neighbouring wild-type cells. These findings lead to the development of a new model to explain the aetiology of HME

Low-Grade Spinal Malignancies: Chordoma and Chondrosarcoma

Chordoma and chondrosarcoma comprise a small group of low-grade malignant primary bone neoplasms that can affect the spine. Chordoma is almost always axial in location and chondrosarcoma can occur both in axial and appendicular locations but can be more aggressive in the axial skeleton. This chapter focuses on the characteristics, pathology, clinical features, and treatment options for these related tumors that characteristically have an abundance of extracellular matrix. Important similarities and differences of these low-grade malignancies are highlighted in this chapter

A novel bioluminescent NanoLuc yeast-estrogen screen biosensor (nanoYES) with a compact wireless camera for effect-based detection of endocrine-disrupting chemicals

The presence of chemicals with estrogenic activity in surface, groundwater, and drinking water poses serious concerns for potential threats to human health and aquatic life. At present, no sensitive portable devices are available for the rapid monitoring of such contamination. Here, we propose a cell-based mobile platform that exploits a newly developed bioluminescent yeast-estrogen screen (nanoYES) and a low-cost compact camera as light detector. Saccharomyces cerevisiae cells were genetically engineered with a yeast codon-optimized variant of NanoLuc luciferase (yNLucP) under the regulation of human estrogen receptor α activation. Ready-to-use 3D-printed cartridges with immobilized cells were prepared by optimizing a new procedure that enables to produce alginate slices with good reproducibility. A portable device was obtained exploiting a compact camera and wireless connectivity enabling a rapid and quantitative evaluation (1-h incubation at room temperature) of total estrogenic activity in small sample volumes (50 Î1⁄4L) with a LOD of 0.08 nM for 17Î2-estradiol. The developed portable analytical platform was applied for the evaluation of water samples spiked with different chemicals known to have estrogen-like activity. Thanks to the high sensitivity of the newly developed yeast biosensor and the possibility to wireless connect the camera with any smartphone model, the developed configuration is more versatile than previously reported smartphone-based devices, and could find application for on-site analysis of endocrine disruptors. [Figure not available: see fulltext.]