A common hallmark of several neuropsychiatric conditions is an altered protein homeostasis. In this context, ubiquitination has emerged as one of the most important post-translational modifications, regulating various intracellular processes such as protein degradation, autophagy, protein activation, and protein–protein interactions. Ubiquitination can be reversed by the activity of several deubiquitinating enzymes (DUBs), and it is of utmost importance that both processes remain in balance. Understanding the extent to which this system is involved in specific brain disorders opens up new possibilities for treating a broader spectrum of patients by targeting this central hub. In recent years, the attention to one of those DUBs, called CYLD, has increased sharply, but with relatively little focus on the central nervous system (CNS): 55 results for “CYLD Brain” vs. 895 results for “CYLD” in total (NCBI Pubmed search, 17.01.2025). Thus, we aim to provide a first overview of the new findings from the past decade specifically related to the role of CYLD in the physiology and pathology of the CNS.

Neural stem cells reside in the subgranular zone, a specialized neurogenic niche of the hippocampus. Throughout adulthood, these cells give rise to neurons in the dentate gyrus, playing an important role in learning and memory. Given that these core cognitive processes are disrupted in numerous disease states, understanding the underlying mechanisms of neural stem cell proliferation in the subgranular zone is of direct practical interest. Here, we report that mature neurons, neural stem cells and neural precursor cells each secrete the neurovascular protein epidermal growth factor-like protein 7 (EGFL7) to shape this hippocampal niche. We further demonstrate that EGFL7 knock-out in a Nestin-CreERT2-based mouse model produces a pronounced upregulation of neurogenesis within the subgranular zone. RNA sequencing identified that the increased expression of the cytokine VEGF-D correlates significantly with the ablation of EGFL7. We substantiate this finding with intraventricular infusion of VEGF-D upregulating neurogenesis in vivo and further show that VEGF-D knock-out produces a downregulation of neurogenesis. Finally, behavioral studies in EGFL7 knock-out mice demonstrate greater maintenance of spatial memory and improved memory consolidation in the hippocampus by modulation of pattern separation. Taken together, our findings demonstrate that both EGFL7 and VEGF-D affect neurogenesis in the adult hippocampus, with the ablation of EGFL7 upregulating neurogenesis, increasing spatial learning and memory, and correlating with increased VEGF-D expression.

Neural stem cells reside in a specialized neurogenic niche of the hippocampus termed the subgranular zone. Throughout life, they give rise to adult-born neurons in the dentate gyrus thereby contributing to learning and memory. Here, we report that neurons together with neural stem and precursor cells secrete the neurovascular protein epidermal growth factor-like protein 7 (EGFL7) to shape this niche. EGFL7 knock-out in vivo promoted adult neurogenesis generating neurons forming additional spines which permanently integrated into the neural circuit until old age. RNA-sequencing identified the cytokine VEGF-D as a major molecular driver of this process in vivo . In behavioral studies EGFL7 knock-out mice displayed stronger maintenance of memory suggesting longer-lasting spatial memory and improved memory consolidation in the hippocampus by modulation of pattern separation in young and aged mice. Taken together, EGFL7 is an upstream regulator of the VEGF-D in adult neurogenesis and a key regulator of learning and memory.

Autism spectrum disorder (ASD) comprises a group of multifactorial neurodevelopmental disorders primarily characterized by deficits in social interaction and repetitive behavior. Although the onset is typically in early childhood, ASD poses a lifelong challenge for both patients and caretakers. Adult neurogenesis (AN) is the process by which new functional neurons are created from neural stem cells existing in the post‐natal brain. The entire event is based on a sequence of cellular processes, such as proliferation, specification of cell fate, maturation, and ultimately, synaptic integration into the existing neural circuits. Hence, AN is implicated in structural and functional brain plasticity throughout life. Accumulating evidence shows that impaired AN may underlie some of the abnormal behavioral phenotypes seen in ASD. In this review, we approach the interconnections between the molecular pathways related to AN and ASD. We also discuss existing therapeutic approaches targeting such pathways both in preclinical and clinical studies. A deeper understanding of how ASD and AN reciprocally affect one another could reveal important converging pathways leading to the emergence of psychiatric disorders.

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 malignant glioma. We found that the encoded extracellular matrix protein epidermal growth factor‐like protein 7 (EGFL7) was secreted by glioma blood vessels but not glioma cells themselves, while no major role could be assigned to the parasitic miRNAs miR‐126/126*. EGFL7 expression promoted glioma growth in experimental glioma models in vivo and stimulated tumor vascularization. Mechanistically, this was mediated by an upregulation of integrin α5β1 on the cellular surface of endothelial cells, which enhanced fibronectin‐induced angiogenic sprouting. Glioma blood vessels that formed in vivo were more mature as determined by pericyte and smooth muscle cell coverage. Furthermore, these vessels were less leaky as measured by magnetic resonance imaging of extravasating contrast agent. EGFL7‐inhibition using a specific blocking antibody reduced the vascularization of experimental gliomas and increased the life span of treated animals, in particular in combination with anti‐VEGF and the chemotherapeutic agent temozolomide. Data allow for the conclusion that this combinatorial regimen may serve as a novel treatment option for GBM. Glioblastoma are lethal brain tumors with currently no cure available. Combinatorial inhibition of the proangiogenic proteins EGFL7 and VEGF together with the chemotherapeutic agent temozolomide may serve as a novel treatment option for patients suffering from this futile disease. Glioblastoma are lethal brain tumors with currently no cure available. Combinatorial inhibition of the proangiogenic proteins EGFL7 and VEGF together with the chemotherapeutic agent temozolomide may serve as a novel treatment option for patients suffering from this futile disease.

Extracellular matrix (ECM) proteins secreted by blood-brain barrier (BBB) endothelial cells (ECs) are implicated in cell trafficking. We discovered that the expression of ECM epidermal growth factor-like protein 7 (EGFL7) is increased in the CNS vasculature of patients with multiple sclerosis (MS), and in mice with experimental autoimmune encephalomyelitis (EAE). Perivascular CD4 T lymphocytes colocalize with ECM-bound EGFL7 in MS lesions. Human and mouse activated T cells upregulate EGFL7 ligand αvβ3 integrin and can adhere to EGFL7 through integrin αvβ3. EGFL7-knockout (KO) mice show earlier onset of EAE and increased brain and spinal cord parenchymal infiltration of T lymphocytes. Importantly, EC-restricted EGFL7-KO is associated with a similar EAE worsening. Finally, treatment with recombinant EGFL7 improves EAE, reduces MCAM expression, and tightens the BBB in mouse. Our data demonstrate that EGFL7 can limit CNS immune infiltration and may represent a novel therapeutic avenue in MS.

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 cell interface. Fewer inhibitory neurons form in the OB of EGFL7 -knockout mice, which increases the absolute signal conducted from the mitral cell layer of the OB but decreases neuronal network synchronicity. Consequently, EGFL7 -knockout mice display severe physiological defects in olfactory behaviour and perception.

The contribution of microglia to ischemic cortical stroke is of particular therapeutic interest because of the impact on the survival of brain tissue in the ischemic penumbra, a region that is potentially salvable upon a brain infarct. Whether or not tissue in the penumbra survives critically depends on blood flow and vessel perfusion. To study the role of microglia in cortical stroke and blood vessel stability, CX3CR1 +/GFP mice were subjected to transient middle cerebral artery occlusion and then microglia were investigated using time-lapse two-photon microscopy in vivo. Soon after reperfusion, microglia became activated in the stroke penumbra and started to expand cellular protrusions towards adjacent blood vessels. All microglia in the penumbra were found associated with blood vessels within 24 h post reperfusion and partially fully engulfed them. In the same time frame blood vessels became permissive for blood serum components. Migration assays in vitro showed that blood serum proteins leaking into the tissue provided molecular cues leading to the recruitment of microglia to blood vessels and to their activation. Subsequently, these perivascular microglia started to eat up endothelial cells by phagocytosis, which caused an activation of the local endothelium and contributed to the disintegration of blood vessels with an eventual break down of the blood brain barrier. Loss-of-microglia-function studies using CX3CR1 GFP/GFP mice displayed a decrease in stroke size and a reduction in the extravasation of contrast agent into the brain penumbra as measured by MRI. Potentially, medication directed at inhibiting microglia activation within the first day after stroke could stabilize blood vessels in the penumbra, increase blood flow, and serve as a valuable treatment for patients suffering from ischemic stroke.

EGFL7 ligates avb3 integrin to enhance vessel formation Iva Nikolić, Nevenka Dudvarski Stanković, Frank Bicker, Jeannette Meister, Helene Braun, Khader Awwad, Jan Baumgart, Kirsten Simon, Serge C. Thal, Chinmoy Patra, Patrick N. Harter, Karl H. Plate, Felix B. Engel, Stefanie Dimmeler, Johannes A. Eble, Michel Mittelbronn, Michael K. Schäfer, Benno Jungblut, Emmanouil Chavakis, Ingrid Fleming, and Mirko H. H. Schmidt

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 to a severe integrin-dependent malformation of the caudal venous plexus, pointing toward the significance of EGFL7 in vessel development. In biopsy specimens of patients with neurologic diseases, vascular EGFL7 expression rose with increasing EC proliferation. Further, EGFL7 became upregulated in vessels of the stroke penumbra using a mouse model of reversible middle cerebral artery occlusion. Our data suggest that EGFL7 expression depends on the remodeling state of the existing vasculature rather than on the phenotype of neurologic disease analyzed. In sum, our work sheds a novel light on the molecular mechanism EGFL7 engages to govern physiological and pathological angiogenesis.

EGFL7 drives the formation of neurons from neural stem cells. In the embryonic and adult brain this process is essential for neurogenesis and homeostasis of the nervous system. The function of adult neurogenesis is not fully understood but maybe it supports life-long learning and brain repair after injuries such as stroke. The transition of neural stem cells into mature neurons is tightly regulated. One of the essential signaling pathways governing this process is the Notch pathway, which controls metazoan development. In a recent publication, we identified a novel non-canonical Notch ligand, EGFL7, and described its impact on neural stem cells.1 We explored the molecular mechanisms, which this molecule affects to regulate the self-renewal capacity of neural stem cells and to promote their differentiation into neurons. In this review, we discuss the implications of our findings for adult neurogenesis and illustrate the potential of EGFL7 to serve as an agent to increase neurogenesis and the self-renewal potential of the brain.

Nature Cell Biol. 11, 873–880 (2009); published online 7 June 2008; corrected online 2 July 2009 In the version of this article initially published online, the labelling of the boxes in Fig. 1b was incorrect. In Fig. 1d the mNotch 2 values were missing, in Fig. 1g the Anti-EGFL7 was incorrectly labelled.

Screening for cytogenetic aberrations with a selected panel of FISH probes has identified important prognostic subgroups in chronic lymphocytic leukemia (CLL). Good prognosis CLL patients with deletions of the long arm of chromosome 13 (del13q) as sole aberration are opposed by patients with deletions of the short arm of chromosome 17 (del17p). The tumor suppressor gene TP53 is located at 17p13 and loss of TP53 is hypothesized to be at least partially responsible for the poor prognosis of del17p CLL patients. However, it is not clear, if the loss of other genes in the deleted region contributes to the poor prognosis. In addition, the degree of overlap between the patient populations defined by del17p and TP53 mutation is only poorly defined. Therefore, we characterized peripheral blood or bone marrow samples of 193 CLL patients by FISH analysis and screened for TP53 mutations by two methods, i.e. by denaturing high performance liquid chromatography (dHPLC) and by a microarray-based resequencing assay, the AmpliChip p53 Test. PCR products of exons 3–9 of TP53 were screened by dHPLC and aberrant fragments were analyzed by direct sequencing, whereas the entire coding region including the splice sites of exons 2–11 were analyzed with the AmpliChip p53 Test. The overall incidence of TP53 mutations by both methods was 13.5% (26/193), whereas the incidence of del17p by FISH was 9.3% (18/193). Interestingly, 17 out the 18 del17p samples carried a TP53 mutation suggesting that loss of TP53 does indeed play a pivotal role in the poor prognosis of del17p. At least 9 samples carried a TP53 mutation only. The AmpliChip p53 Test detected 32 mutations in 25 patients compared to 24 mutations detected in 20 patients by dHPLC/direct sequencing. The AmpliChip p53 Test, which is designed to detect single nucleotide substitutions and single nucleotide deletions, did not detect 3 mutations (1 1-bp deletion, 1 4-bp deletions, 1 single nucleotide insertion). The method of dHPLC followed by direct sequencing did not call 10 single nucleotide mutations. Of these, 1 mutation was located in exon 10 not included in the dHPLC screening. The remaining 9 mutations were detected by dHPLC analysis, but failed to be called by direct sequencing. The clinical course of patients with TP53 aberrations (n=20) (del17p and/or TP53 mutation) was compared to 113 patients lacking these abnormalities. Patients with TP53 aberration had a highly significantly decreased time to progression compared to patients without TP53 aberration (p<0.001, median 13.2 vs. 64.4 months). This difference remained significant when analysis was restricted to patient samples without prior therapy (p<0.001, median 9.2 (n=13) vs. 70.6 months (n=101)). As FISH analysis for del17p is the standard approach to detect TP53 aberrations, we compared the clinical course of patients with del17p (n=8) to patients with TP53 mutation (without del17p) (n=7) vs patients without TP53 aberration (n=113). This analysis resulted in a median time to progression of 9.2 vs 22.4 vs 63.4 month, respectively (p<0.001). The data of the present analysis suggest that TP53 mutation might be one of the factors conferring poor prognosis to CLL patients. Likewise, we identified 9 samples (4.7%) with TP53 mutation alone with poor clinical course that would have escaped detection by FISH analysis.

Die Erfindung betrifft die Verwendung eines Polynukleotids zur Modulation von Stammzellen. Erfindungsgemas kodiert das Polynukleotid fur a) ein EGFL7 Polypeptid oder fur dessen gleichwirkende Polypeptidfragmente, oder b) ein Polypeptid, dass mindestens 80% Sequenzidentitat zu den unter a) genannten Polypeptid oder Polypeptidfragmenten aufweist und welches zu dem EGFL7 Polypeptid gleichwirkend ist, oder c) ein Polypeptid, dass mit einem unter a) und b) genannten Polypeptid oder Polypeptidfragement inhibierend in Wechselwirkung tritt.