Neurovascular EGFL7 regulates adult neurogenesis in the subventricular zone and thereby affects olfactory perception

Adult neural stem cells reside in a specialized niche in the subventricular zone (SVZ). Throughout life they give rise to adult-born neurons in the olfactory bulb (OB), thus contributing to neural plasticity and pattern discrimination. Here, we show that the neurovascular protein EGFL7 is secreted by endothelial cells and neural stem cells (NSCs) of the SVZ to shape the vascular stem-cell niche. Loss of EGFL7 causes an accumulation of activated NSCs, which display enhanced activity and re-entry into the cell cycle. EGFL7 pushes activated NSCs towards quiescence and neuronal progeny towards differentiation. This is achieved by promoting Dll4-induced Notch signalling at the blood vessel-stem …

The soluble form of pan-RTK inhibitor and tumor suppressor LRIG1 mediates downregulation of AXL through direct protein–protein interaction in glioblastoma

Abstract Background Targeted approaches for inhibiting epidermal growth factor receptor (EGFR) and other receptor tyrosine kinases (RTKs) in glioblastoma (GBM) have led to therapeutic resistance and little clinical benefit, raising the need for the development of alternative strategies. Endogenous LRIG1 (Leucine-rich Repeats and ImmunoGlobulin-like domains protein 1) is an RTK inhibitory protein required for stem cell maintenance, and we previously demonstrated the soluble ectodomain of LRIG1 (sLRIG1) to potently inhibit GBM growth in vitro and in vivo. Methods Here, we generated a recombinant protein of the ectodomain of LRIG1 (sLRIG1) and determined its activity in various cellular GBM mo…

Progranulin overexpression in sensory neurons attenuates neuropathic pain in mice: Role of autophagy

Peripheral or central nerve injury is a frequent cause of chronic pain and the mechanisms are not fully understood. Using newly generated transgenic mice we show that progranulin overexpression in sensory neurons attenuates neuropathic pain after sciatic nerve injury and accelerates nerve healing. A yeast-2-hybrid screen revealed putative interactions of progranulin with autophagy-related proteins, ATG12 and ATG4b. This was supported by colocalization and proteomic studies showing regulations of ATG13 and ATG4b and other members of the autophagy network, lysosomal proteins and proteins involved in endocytosis. The association of progranulin with the autophagic pathway was functionally confi…

RASSF1A inhibits estrogen receptor alpha expression and estrogen-independent signalling: implications for breast cancer development

The Ras association domain family 1 isoform A (RASSF1A) is a tumor suppressor whose inactivation is implicated in the development of many human cancers, including breast carcinomas. Little is known about the tumor-suppressive function of RASSF1A in breast tissue and whether its inactivation is mechanistically involved in the initiation and progression of breast tumors. Here, we show that RASSF1A inhibits breast cancer growth in vivo, and suppresses estrogen receptor (ERα) expression and function. Reconstitution of RASSF1A in MCF7 cells led to decreased ERα levels and reduced sensitivity to estrogen (E2). Concomitantly, we observed decreased expression of Id1 as well as the E2-responsive gen…

OS1.5 Harnessing soluble LRIG1 for pan-RTK targeting in glioblastoma

INTRODUCTION: The role of receptor tyrosine kinases (RTKs) in glioblastoma is widely acknowledged. However, therapies based on RTK targeting have been continuously unsuccessful in GBM patients, highlighting the complexity of RTK signaling and biology. LRIG1 (Leucine-rich Repeats and ImmunoGlobulin domains protein 1) was identified as an endogenous inhibitor of epidermal growth factor receptor (EGFR) and other RTKs, and was confirmed as a tumor suppressor in various cancer types. We previously identified the soluble form of LRIG1 as a potent inhibitor of GBM growth in vivo, irrespective of EGFR status. Here, we aim to shed light on the molecular mechanisms underlying its anti-cancer activity…

EGFL7 ligates αvβ3 integrin to enhance vessel formation

Angiogenesis, defined as blood vessel formation from a preexisting vasculature, is governed by multiple signal cascades including integrin receptors, in particular integrin αVβ3. Here we identify the endothelial cell (EC)-secreted factor epidermal growth factor-like protein 7 (EGFL7) as a novel specific ligand of integrin αVβ3, thus providing mechanistic insight into its proangiogenic actions in vitro and in vivo. Specifically, EGFL7 attaches to the extracellular matrix and by its interaction with integrin αVβ3 increases the motility of EC, which allows EC to move on a sticky underground during vessel remodeling. We provide evidence that the deregulation of EGFL7 in zebrafish embryos leads …

Resilience and Vulnerability to Pain and Inflammation in the Hippocampus

Increasing evidence demonstrates the importance of hippocampal neurogenesis, a fundamental mechanism of neuroplasticity associated with cognition and emotion, in correlation to neurodegenerative and psychiatric disorders. Neuropsychiatric disorders are often a result of chronic stress or pain followed by inflammation; all these conditions manifest cognitive deficits and impairments in neurogenesis. However, while some individuals are more susceptible to stress, others are able to adapt to new environments via mechanisms of resilience. In light of this emerging field and based on extensive research, the role of neurogenesis is summarized and presented as a potentially powerful therapeutic to…

VEGF and Notch Signaling in Angiogenesis

The vascular system is responsible for providing every cell in vertebrate organisms with a sufficient supply of oxygen and nutrients, allowing waste disposal as well as transmitting immune responses among other functions. Thus, every tissue and organ requires an efficient network of blood vessels, which can be formed de novo (vasculogenesis) or from existing vessels (angiogenesis). The onset of the latter, namely endothelial cell (EC) sprouting, is the focus of this chapter. EC sprouting starts with the differentiation of ECs into guiding tip cells and proliferative stalk cells that form the growing sprout and it ends with the so-called anastomosis, when the sprout fuses with another sprout…

EGFL7 enhances surface expression of integrin α5β1 to promote angiogenesis in malignant brain tumors

Abstract Glioblastoma (GBM) is a typically lethal type of brain tumor with a median survival of 15 months postdiagnosis. This negative prognosis prompted the exploration of alternative treatment options. In particular, the reliance of GBM on angiogenesis triggered the development of anti‐VEGF (vascular endothelial growth factor) blocking antibodies such as bevacizumab. Although its application in human GBM only increased progression‐free periods but did not improve overall survival, physicians and researchers still utilize this treatment option due to the lack of adequate alternatives. In an attempt to improve the efficacy of anti‐VEGF treatment, we explored the role of the egfl7 gene in ma…

P11.09 Pan-RTK inhibition of sLRIG1 mediates AXL downregulation in Glioblastoma

Abstract INTRODUCTION Aberrant regulation of receptor tyrosine kinase (RTK) activity is characteristic of Glioblastoma (GBM). However, RTK-based targeted therapies have been largely unsuccessful in GBM patients, partially due to the complexity and redundance of RTK signaling. LRIG1 (Leucine-rich Repeats and ImmunoGlobulindomains protein 1) is known as an endogenous inhibitor of epidermal growth factor receptor (EGFR) during health and disease, however its mechanism of action is poorly understood. We previously showed that the soluble form of LRIG1 potently inhibits of GBM growth in vivo, irrespective of EGFR expression level and status, suggesting the involvement of other RTKs. Here, we aim…

Corrigendum to "Human periodontal fibroblast response to a nanostructured hydroxyapatite bone replacement graft in vitro" [Arch. Oral Biol. 53 July (7) (2008) 683-689].

Ability of nanocrystalline hydroxyapatite paste to promote human periodontal ligament cell proliferation.

Recent studies indicate that nanocrystalline hydroxyapatite (nano-HA) paste represents a promising class of bone graft substitute. However, the underlying molecular mechanisms of nano-HA function have not yet been determined. This study was conducted to investigate the proliferation of human periodontal ligament (PDL) cells cultured in the presence of nano-HA paste and to characterize associated changes in intracellular signaling pathways. Cultured PDL cells were stimulated with nano-HA paste and enamel matrix derivative (EMD) in a soluble form. Proliferation of PDL cells was determined by incorporation of bromodeoxyuridine (BrdU) in the DNA of proliferating cells. In order to understand th…

P08.76 Anti-EGFL7 treatment as an add-on for glioma therapy

Glioblastoma multiforme (GBM) is one the most common and malignant forms of brain tumors. The median survival time of patients diagnosed with primary GBM is around 15 months. In spite of multimodal treatments GBMs remain essentially incurable. Therefore, alternative treatments targeting previously unexplored aspects of GBMs are required. However, the molecular mechanisms underlying the formation of brain tumors have only partially been defined. Especially Notch, a conserved developmental pathway, is promising in terms of GBM formation, as components of this signaling cascade are aberrantly expressed in gliomas. Studies reported that the inhibition of Notch decreased glioma cell proliferatio…

Recommendations of the working group of the Anatomische Gesellschaft on reduction of formaldehyde exposure in anatomical curricula and institutes.

The practice of human and veterinary medicine is based on the science of anatomy and dissection courses are still irreplaceable in the teaching of anatomy. Embalming is required to preserve body donors, for which process formaldehyde (FA) is the most frequently used and well characterized biocidal substance. Since January 2016, a new occupational exposure limit (OEL) for FA of 0.37mg/m3 issued by the European Committee on Hazardous Substances is obligatory since FA has been classified as a human 1B carcinogen. The anatomical institutes in the German-speaking region are called upon to consolidate efforts to reduce use of FA in anatomical curricula and body donations. As a result, the Anatomi…