Probes for INS

Abstract

BACKGROUND:

Discoidin domain receptor 1 (DDR1) is a collagen-activated receptor tyrosine kinase extensively implicated in diseases such as cancer, atherosclerosis and fibrosis. Multiple preclinical studies, performed using either a gene deletion or a gene silencing approaches, have shown this receptor being a major driver target of fibrosis and glomerulosclerosis.

METHODS:

The present study investigated the role and relevance of DDR1 in human crescentic glomerulonephritis (GN). Detailed DDR1 expression was first characterized in detail in human GN biopsies using a novel selective anti-DDR1 antibody using immunohistochemistry. Subsequently the protective role of DDR1 was investigated using a highly selective, novel, small molecule inhibitor in a nephrotoxic serum (NTS) GN model in a prophylactic regime and in the NEP25 GN mouse model using a therapeutic intervention regime.

RESULTS:

DDR1 expression was shown to be mainly limited to renal epithelium. In humans, DDR1 is highly induced in injured podocytes, in bridging cells expressing both parietal epithelial cell (PEC) and podocyte markers and in a subset of PECs forming the cellular crescents in human GN. Pharmacological inhibition of DDR1 in NTS improved both renal function and histological parameters. These results, obtained using a prophylactic regime, were confirmed in the NEP25 GN mouse model using a therapeutic intervention regime. Gene expression analysis of NTS showed that pharmacological blockade of DDR1 specifically reverted fibrotic and inflammatory gene networks and modulated expression of the glomerular cell gene signature, further validating DDR1 as a major mediator of cell fate in podocytes and PECs.

CONCLUSIONS:

Together, these results suggest that DDR1 inhibition might be an attractive and promising pharmacological intervention for the treatment of GN, predominantly by targeting the renal epithelium.

Hyaluronan (HA) plays an important role in the development and maintenance of tissues, and its degradation is implicated in many pathologic conditions. We recently reported that HA-binding protein involved in HA depolymerization (HYBID/KIAA1199; encoded by CEMIP) is a key molecule in HA depolymerization, but its developmental and pathologic functions remain elusive. We generated Hybid-deficient mice using the Cre/locus of crossover in P1 (loxP) system and analyzed their phenotypes. Hybid-deficient mice were viable and fertile, but their adult long bones were shorter than those of wild-type animals. Hybid-deficient mice showed lengthening of hypertrophic zone in the growth plate until 4 weeks after birth. There were fewer capillaries and osteoclasts at the chondroosseous junction in the Hybid-deficient mice compared with the wild-type mice. In situ hybridization demonstrated that Hybid was expressed by hypertrophic chondrocytes at the chondroosseous junction. Cultured primary chondrocytes expressed higher levels of Hybid than did osteoblasts or osteoclasts, and the Hybid expression in the chondrocytes was up-regulated after maturation to hypertrophic chondrocytes. High-molecular-weight HA was accumulated in the lengthened hypertrophic zone in Hybid-deficient mice. In addition, high-molecular-weight HA significantly reduced cell growth and tube formation in vascular endothelial growth factor-stimulated or -nonstimulated endothelial cells. HA metabolism by HYBID is involved in endochondral ossification during postnatal development by modulation of angiogenesis and osteoclast recruitment at the chondroosseous junction.

Deficiency of vascular endothelial growth factor A (VEGF) has been associated with severe craniofacial anomalies in both humans and mice. Cranial neural crest cell (NCC)-derived VEGF regulates proliferation, vascularization and ossification of cartilage and membranous bone. However, the function of VEGF derived from specific subpopulations of NCCs in controlling unique aspects of craniofacial morphogenesis is not clear. In this study a conditional knockdown strategy was used to genetically delete Vegfa expression in Osterix (Osx) and collagen II (Col2)-expressing NCC descendants. No major defects in calvaria and mandibular morphogenesis were observed upon knockdown of VEGF in the Col2+ cell population. In contrast, loss of VEGF in Osx+ osteoblast progenitor cells led to reduced ossification of calvarial and mandibular bones without affecting the formation of cartilage templates in newborn mice. The early stages of ossification in the developing jaw revealed decreased initial mineralization levels and a reduced thickness of the collagen I (Col1)-positive bone template upon loss of VEGF in Osx+ precursors. Increased numbers of proliferating cells were detected within the jaw mesenchyme of mutant embryos. Explant culture assays revealed that mandibular osteogenesis occurred independently of paracrine VEGF action and vascular development. Reduced VEGF expression in mandibles coincided with increased phospho-Smad1/5 (P-Smad1/5) levels and bone morphogenetic protein 2 (Bmp2) expression in the jaw mesenchyme. We conclude that VEGF derived from Osx+ osteoblast progenitor cells is required for optimal ossification of developing mandibular bones and modulates mechanisms controlling BMP-dependent specification and expansion of the jaw mesenchyme.

Gastric cancer is the fifth most common cancer and third leading cause of cancer-related death worldwide. Several studies on angiogenic blocking agents in gastric cancer revealing promising results by the use of monoclonal antibodies against VEGFA or its receptor VEGFR2 or against VEGFA activating pathway. The validation of biomarkers useful to better organize the clinical trials involving anti-angiogenic therapies is crucial. Molecular markers such as RNA are increasingly used for cancer diagnosis, prognosis, and therapy guidance as in the case of the targeted therapies concerning the inhibition of angiogenesis. The aim of this study is to set the conditions for evaluating the expression of VEGFA and VEGFR2 in gastric cancer specimens and in healthy gastric mucosa by the use of RNAscope, a novel RNA in situ hybridization (ISH) method that allows the visualization of a specific gene expression in individual cells. We found the increased expression of VEGFA in the tubular glands and VEGFR2 in the endothelium of gastric cancer samples mainly in the T2, T3 and T4 stages of tumor progression as compared to the healthy controls. These results obtained by the application of this highly sensitive method for oligonucleotide detection the role of angiogenesis in gastric cancer progression already highlighted by conventional immunohistochemical methods, and offer significant promise as a new platform for developing and implementing RNA-based molecular diagnostics also in the conditions in which immunohistochemistry is not applicable.

Abstract