Nephron-Specific Lin28A Overexpression Triggers Severe Inflammatory Response and Kidney Damage.

The RNA-binding proteins LIN28A and LIN28B contribute to a variety of developmental biological processes. Dysregulation of Lin28A and Lin28B expression is associated with numerous types of tumors. This study demonstrates that Lin28A overexpression in the mouse nephrons leads to severe inflammation and kidney damage rather than to tumorigenesis. Notably, Lin28A overexpression causes inflammation only when expressed in nephrons, but not in the stromal cells of the kidneys, highlighting its cell context-dependent nature. The nephron-specific Lin28A-induced inflammatory response differs from previously described Lin28B-mediated inflammatory feedback loops as it is IL-6 independent. Instead, it is associated with the rapid upregulation of cytokines like Cxcl1 and Ccl2. These findings suggest that the pathophysiological effects of Lin28A overexpression extend beyond cell transformation. Our transgenic mouse model offers a valuable tool for advancing our understanding of the pathophysiology of acute kidney injury, where inflammation is a key factor.

Diet-induced modifications to human microbiome reshape colonic homeostasis in irritable bowel syndrome.

Changes in microbiome composition are associated with a wide array of human diseases, turning the human microbiota into an attractive target for therapeutic intervention. Yet, clinical translation of these findings requires the establishment of causative connections between specific microbial taxa and their functional impact on host tissues. Here, we infuse gut organ cultures with longitudinal microbiota samples collected from therapy-naive patients with irritable bowel syndrome (IBS) under a low-fermentable oligo-, di-, mono-saccharides and polyols (FODMAP) diet. We show that post-diet microbiota regulates intestinal expression of inflammatory and neuro-muscular gene sets. Specifically, we identify Bifidobacterium adolescentis as a diet-sensitive pathobiont that alters tight junction integrity and disrupts gut barrier functions. Collectively, we present a pathway discovery platform for mechanistic dissection and identification of functional diet-host-microbiota modules. Our data support the hypothesis that the gut microbiota mediates the beneficial effects of a low-FODMAP diet and reinforce the potential feasibility of microbiome-based therapies in IBS.

Critical Sites on Ostreolysin Are Responsible for Interaction with Cytoskeletal Proteins.

We explored the structural features of recombinant ostreolysin A (rOlyA), a protein produced by Pleurotus ostreatus and responsible for binding to α/ß-tubulin. We found that rOlyA cell internalization is essential for the induction of adipocyte-associated activity, which is mediated by the interaction of rOlyA and microtubule proteins. We created different point mutations at conserved tryptophan (W) sites in rOlyA and analyzed their biological activity in HIB-1B preadipocytes. We demonstrated that the protein's cell-internalization ability and the differentiated phenotype induced, such as small lipid-droplet formation and gene expression of mitogenesis activity, were impaired in point-mutated proteins W96A and W28A, where W was converted to alanine (A). We also showed that an rOlyA homologue, OlyA6 complexed with mCherry, cannot bind to ß-tubulin and does not induce mitochondrial biosynthesis-associated markers, suggesting that the OlyA6 region masked by mCherry is involved in ß-tubulin binding. Protein-protein docking simulations were carried out to investigate the binding mode of rOlyA with ß-tubulin. Taken together, we identified functional sites in rOlyA that are essential for its binding to ß-tubulin and its adipocyte-associated biological activity.

An Engineered Nanocomplex with Photodynamic and Photothermal Synergistic Properties for Cancer Treatment.

Photodynamic therapy (PDT) and photothermal therapy (PTT) are promising therapeutic methods for cancer treatment; however, as single modality therapies, either PDT or PTT is still limited in its success rate. A dual application of both PDT and PTT, in a combined protocol, has gained immense interest. In this study, gold nanoparticles (AuNPs) were conjugated with a PDT agent, meso-tetrahydroxyphenylchlorin (mTHPC) photosensitizer, designed as nanotherapeutic agents that can activate a dual photodynamic/photothermal therapy in SH-SY5Y human neuroblastoma cells. The AuNP-mTHPC complex is biocompatible, soluble, and photostable. PDT efficiency is high because of immediate reactive oxygen species (ROS) production upon mTHPC activation by the 650-nm laser, which decreased mitochondrial membrane potential (∆ψm). Likewise, the AuNP-mTHPC complex is used as a photoabsorbing (PTA) agent for PTT, due to efficient plasmon absorption and excellent photothermal conversion characteristics of AuNPs under laser irradiation at 532 nm. Under the laser irradiation of a PDT/PTT combination, a twofold phototoxicity outcome follows, compared to PDT-only or PTT-only treatment. This indicates that PDT and PTT have synergistic effects together as a combined therapeutic method. Our study aimed at applying the AuNP-mTHPC approach as a potential treatment of cancer in the biomedical field.

The Dynamics of Lamin a During the Cell Cycle.

Lamin proteins play an essential role in maintaining the nuclear organization and integrity; and lamin A, in particular, plays a major role in the whole volume of the nuclear interior. Although the nucleus is highly organized, it is rather dynamic, it affects crucial nuclear processes and its organization must change as cells progress through the cell cycle. Although many aspects of these changes are already known, the role of lamin A during nuclear assembly and disassembly as well as its underlying mechanisms remains controversial. Here we used live cells imaging and Continuous Photobleaching (CP) method to shed light on the dynamics and mechanisms of lamin A during the cell cycle, combined with imaging flow cytometry measurements, which provides the high-throughput capabilities of flow cytometry with single-cell imaging. As a major analysis tool, we used spatial correlation algorithm for allocating the distribution of lamin A, chromatin and tubulin, as well as their mutual colocalization. Furthermore, we analyzed the distribution of lamin A along the nuclear lamina and in the nucleus interior during the cell cycle. Our results indicate that at the beginning of the cell division that include prophase, metaphase and anaphase, lamin A is distributed throughout the cytoplasm and its concentration in the chromosomal regions is reduced, whereas the spatial correlation between lamin A and tubulin is increased. It implies that lamin A also disassembled in the whole cellular volume. At the telophase and early G1, lamin A is concentrated in the whole volume of the newly formed nuclei of the daughter cells and it assembles to the lamina. We also explored the functional aspects of lamin A during the cell cycle and its binding to the chromatin versus the freely diffusion form. We found that the fraction of the bound proteins of lamin A in the S phase increased, relative to the G1 phase, which means that during replication, the concentration of lamin A on the chromatin increases. All these results shed light on the function of lamin A throughout the cell cycle.

Dose optimisation for Loss of Response to Vedolizumab- Pharmacokinetics and Immune Mechanisms.

BACKGROUND: Real life data regarding pharmacokinetics of vedolizumab in patients needing dose optimisation are scarce. We set to examine whether pre-optimisation vedolizumab levels associate with therapy outcomes and which mechanisms explain the associations. METHODS: A multicentre observational study assessed the outcome of dose increase in association with pre-escalation levels in vedolizumab-treated patients. SubsequentIy, α4ß7 occupancy on peripheral blood [PB] and intestinal lamina propria [LP] tissues was investigated on various cellular subsets in patients undergoing lower endoscopy on infusion day. Cellular localisation of vedolizumab-bound α4ß7 and effects on M1 and M2 macrophages were also explored. RESULTS: A total of 161 inflammatory bowel disease [IBD] patients were included. Among 129/161 patients intensified during maintenance [Week 14 onward], pre-intensification trough levels were comparable or higher among those subsequently attaining post-optimisation clinical, biomarker, and endoscopic remission, compared with non-remitting patients [p = 0.09, 0.25, 0.04, respectively]. Similar results were demonstrated for those dose-optimised during induction [Week 6, n = 32]. In the immune sub-study [n = 43], free α4ß7 receptors at trough were similarly low among patients with/without mucosal healing, on PB T cells [p = 0.15], LP T cells [p = 0.88], and on PB eosinophils [p = 0.08]. Integrin receptors on M1 and M2 macrophages were also saturated by low levels of vedolizumab and anti-inflammatory cytokine secretion was not increased. Co-localisation and dissociation experiments demonstrated membranal α4ß7 receptors of two origins: non-internalised and newly generated α4ß7, but re-binding was still complete at very low concentrations. CONCLUSIONS: These results do not support pharmacokinetics as the mechanism responsible for loss of response to vedolizumab, nor do they support a need for higher drug concentration to enhance vedolizumab's immune effects. Higher pre-escalation levels may indicate less clearance [less severe disease] and higher likelihood of subsequent re-gained response, regardless of therapy escalation.

Cannabis compounds exhibit anti-inflammatory activity in vitro in COVID-19-related inflammation in lung epithelial cells and pro-inflammatory activity in macrophages.

Cannabis sativa is widely used for medical purposes and has anti-inflammatory activity. This study intended to examine the anti-inflammatory activity of cannabis on immune response markers associated with coronavirus disease 2019 (COVID-19) inflammation. An extract fraction from C. sativa Arbel strain (FCBD) substantially reduced (dose dependently) interleukin (IL)-6 and -8 levels in an alveolar epithelial (A549) cell line. FCBD contained cannabidiol (CBD), cannabigerol (CBG) and tetrahydrocannabivarin (THCV), and multiple terpenes. Treatments with FCBD and a FCBD formulation using phytocannabinoid standards (FCBD:std) reduced IL-6, IL-8, C-C Motif Chemokine Ligands (CCLs) 2 and 7, and angiotensin I converting enzyme 2 (ACE2) expression in the A549 cell line. Treatment with FCBD induced macrophage (differentiated KG1 cell line) polarization and phagocytosis in vitro, and increased CD36 and type II receptor for the Fc region of IgG (FcγRII) expression. FCBD treatment also substantially increased IL-6 and IL-8 expression in macrophages. FCBD:std, while maintaining anti-inflammatory activity in alveolar epithelial cells, led to reduced phagocytosis and pro-inflammatory IL secretion in macrophages in comparison to FCBD. The phytocannabinoid formulation may show superior activity versus the cannabis-derived fraction for reduction of lung inflammation, yet there is a need of caution proposing cannabis as treatment for COVID-19.

TMF1 is upregulated by insulin and is required for a sustained glucose homeostasis.

Insulin-regulated glucose homeostasis is a critical and intricate physiological process, of which not all regulatory components have been deciphered. One of the key players in modulating glucose uptake by cells is the glucose transporter-GLUT4. In this study, we aimed to explore the regulatory role of the trans-Golgi-associated protein-TATA Element Modulatory Factor (TMF1) in the GLUT4 mediated, insulin-directed glucose uptake. By establishing and using TMF1-/- myoblasts and mice, we examined the effect of TMF1 absence on the insulin driven functioning of GLUT4. We show that TMF1 is upregulated by insulin in myoblasts, and is essential for the formation of insulin responsive, glucose transporter GLUT4-containing vesicles. Absence of TMF1 leads to the retention of GLUT4 in perinuclear compartments, and to severe impairment of insulin-stimulated GLUT4 trafficking throughout the cytoplasm and to the cell plasma membrane. Accordingly, glucose uptake is impaired in TMF1-/- cells, and TMF1-/- mice are hyperglycemic. This is reflected by the mice impaired blood glucose clearance and increased blood glucose level. Correspondingly, TMF1-/- animals are leaner than their normal littermates. Thus, TMF1 is a novel effector of insulin-regulated glucose homeostasis, and dys-functioning of this protein may contribute to the onset of a diabetes-like disorder.

Carbon nanostructures as a scaffold for human embryonic stem cell differentiation toward photoreceptor precursors.

Carbon nanomaterials have been introduced as a scaffold for various biological applications due to their unique physical and electrical properties. Here we studied carbon nanotubes (CNTs) and carbon nanofibers (CNFs) as scaffold materials for the differentiation of human embryonic stem cells (hESCs) towards photoreceptor precursor cells (PRPs). We report on their cytoxicity, their effect on cell morphology, cell-surface interface and the differentiation process. To this end, hESCs were differentiated into PRPs on carbon nanofibers (CNFs), long horizontal CNTs (LHCNTs), vertically aligned CNTs (VACNTs) or glass (control) surfaces. The differentiated cells were investigated by immunohistochemistry, fluorescence imaging and electron microscopy. Our results revealed that the investigated nanomaterials were not cytotoxic to the cells during the differentiation process. The surface interface effect on the cells was apparent, affecting cell directionality, migration and morphology. Interestingly, cell fate was not dependent on the substrate type, as inferred from the similar dynamics of the loss of pluripotency and the comparable expression levels of the photoreceptor marker Crx for all investigated substrates. These results are important for better understanding the effect of nanomaterial surface interaction with differentiating neural cells in general, and for future use of these materials as scaffolds for differentiating photoreceptors for vision restoration in particular.

The Sub-Nuclear Localization of RNA-Binding Proteins in KSHV-Infected Cells.

RNA-binding proteins, particularly splicing factors, localize to sub-nuclear domains termed nuclear speckles. During certain viral infections, as the nucleus fills up with replicating virus compartments, host cell chromatin distribution changes, ending up condensed at the nuclear periphery. In this study we wished to determine the fate of nucleoplasmic RNA-binding proteins and nuclear speckles during the lytic cycle of the Kaposi's sarcoma associated herpesvirus (KSHV). We found that nuclear speckles became fewer and dramatically larger, localizing at the nuclear periphery, adjacent to the marginalized chromatin. Enlarged nuclear speckles contained splicing factors, whereas other proteins were nucleoplasmically dispersed. Polyadenylated RNA, typically found in nuclear speckles under regular conditions, was also found in foci separated from nuclear speckles in infected cells. Poly(A) foci did not contain lncRNAs known to colocalize with nuclear speckles but contained the poly(A)-binding protein PABPN1. Examination of the localization of spliced viral RNAs revealed that some spliced transcripts could be detected within the nuclear speckles. Since splicing is required for the maturation of certain KSHV transcripts, we suggest that the infected cell does not dismantle nuclear speckles but rearranges their components at the nuclear periphery to possibly serve in splicing and transport of viral RNAs into the cytoplasm.

A single nucleotide variant of human PARP1 determines response to PARP inhibitors.

The introduction of novel cancer drugs and innovative treatments brings great hope for cancer patients, but also an urgent need to match drugs to suitable patients, since certain drugs that benefit one patient may actually harm others. The newly developed poly-ADP ribose polymerase (PARP) inhibitors (PARPis) are a group of pharmacological enzyme inhibitors used clinically for multiple indications. Several forms of cancer tend to be PARP dependent, making PARP an attractive target for cancer therapy. Specifically, PARPis are commonly used in BRCA-associated breast cancers patients, since unrepaired single-strand breaks are converted into double-strand breaks and BRCA-associated tumors cannot repair them by homologous recombination so that PARPi leads to tumor cell death, by a mechanism called "Synthetic Lethality". Unfortunately, not all patients respond to PARPi, and it is not currently possible to predict who will or will not respond. Here, we present a specific genomic marker, which reflects a single-nucleotide polymorphism of human PARP1 and correlates in vitro with response to PARPi, throughout all indications. In addition, we report that this SNP is associated with re-shaping mRNA, and mRNA levels, and influences the final protein structure to expose new binding sites while hiding others. The status of the SNP is therefore critical to patients' care, as it relates responses to PARPi to the PARP1-SNP carried.

Characterization of PfiT/PfiA toxin-antitoxin system of Pseudomonas aeruginosa that affects cell elongation and prophage induction.

Toxin-antitoxin (TA) systems are small genetic modules usually consisting of two elements-a toxin and an antitoxin. The abundance of TA systems among various bacterial strains may indicate an important evolutionary role. Pseudomonas aeruginosa, which can be found in a variety of niches in nature, is an opportunistic pathogen for various hosts. While P. aeruginosa strains are very versatile and diverse, only a few TA systems were characterized in this species. Here, we describe a newly characterized TA system in P. aeruginosa that is encoded within the filamentous Pf4 prophage. This system, named PfiT/PfiA, is a homologue of the ParE/YefM TA system. It is a type II TA system, in which the antitoxin is a protein that binds the toxic protein and eliminates the toxic effect. PfiT/PfiA carries several typical type II characteristics. Specifically, it constitutes two small genes expressed in a single operon, PfiT inhibits growth and PfiA eliminates this effect, PfiA binds PfiT, and PfiT expression results in elongated cells. Finally, we assigned a novel function to this TA system, where an imbalance between PfiT and PfiA, favouring the toxin, resulted in cell elongation and an increase in virion production.

Type Three Secretion System-Dependent Microvascular Thrombosis and Ischemic Enteritis in Human Gut Xenografts Infected with Enteropathogenic Escherichia coli.

Enteropathogenic Escherichia coli (EPEC) is a leading cause of severe intestinal disease and infant mortality in developing countries. Virulence is mediated by a type three secretion system (T3SS), causing the hallmark attaching and effacing (AE) lesions and actin-rich pedestal formation beneath the infecting bacteria on the apical surface of enterocytes. EPEC is a human-specific pathogen whose pathogenesis cannot be studied in animal models. We therefore established an EPEC infection model in human gut xenografts in SCID mice and used it to study the role of T3SS in the pathogenesis of the disease. Following EPEC O127:H6 strain E2348/69 infection, T3SS-dependent AE lesions and pedestals were demonstrated in all infected xenografts. We report here the development of T3SS-dependent intestinal thrombotic microangiopathy (iTMA) and ischemic enteritis in ∼50% of infected human gut xenografts. Using species-specific CD31 immunostaining, we showed that iTMA was limited to the larger human-mouse chimeric blood vessels, which are located between the muscularis mucosa and circular muscular layer of the human gut. These blood vessels were massively invaded by bacteria, which adhered to and formed pedestals on endothelial cells and aggregated with mouse neutrophils in the lumen. We conclude that endothelial infection, iTMA, and ischemic enteritis might be central mechanisms underlying severe EPEC-mediated disease.

Developing in vitro expanded CD45RA+ regulatory T cells as an adoptive cell therapy for Crohn's disease.

BACKGROUND AND AIM: Thymus-derived regulatory T cells (Tregs) mediate dominant peripheral tolerance and treat experimental colitis. Tregs can be expanded from patient blood and were safely used in recent phase 1 studies in graft versus host disease and type 1 diabetes. Treg cell therapy is also conceptually attractive for Crohn's disease (CD). However, barriers exist to this approach. The stability of Tregs expanded from Crohn's blood is unknown. The potential for adoptively transferred Tregs to express interleukin-17 and exacerbate Crohn's lesions is of concern. Mucosal T cells are resistant to Treg-mediated suppression in active CD. The capacity for expanded Tregs to home to gut and lymphoid tissue is unknown. METHODS: To define the optimum population for Treg cell therapy in CD, CD4(+)CD25(+)CD127(lo)CD45RA(+) and CD4(+)CD25(+)CD127(lo)CD45RA(-) Treg subsets were isolated from patients' blood and expanded in vitro using a workflow that can be readily transferred to a good manufacturing practice background. RESULTS: Tregs can be expanded from the blood of patients with CD to potential target dose within 22-24 days. Expanded CD45RA(+) Tregs have an epigenetically stable FOXP3 locus and do not convert to a Th17 phenotype in vitro, in contrast to CD45RA(-) Tregs. CD45RA(+) Tregs highly express α4ß7 integrin, CD62L and CC motif receptor 7 (CCR7). CD45RA(+) Tregs also home to human small bowel in a C.B-17 severe combined immune deficiency (SCID) xenotransplant model. Importantly, in vitro expansion enhances the suppressive ability of CD45RA(+) Tregs. These cells also suppress activation of lamina propria and mesenteric lymph node lymphocytes isolated from inflamed Crohn's mucosa. CONCLUSIONS: CD4(+)CD25(+)CD127(lo)CD45RA(+) Tregs may be the most appropriate population from which to expand Tregs for autologous Treg therapy for CD, paving the way for future clinical trials.

Antagonistic activities of Rho and Rac GTPases underlie the transition from neural crest delamination to migration.

BACKGROUND: Neural crest progenitors arise as epithelial cells and then undergo a transition into mesenchyme that generates motility. Previously, we showed that active Rho maintains crest cells in the epithelial conformation by keeping stress fibers and membrane-bound N-cadherin. RESULTS: While Rho disappears from cell membranes upon delamination, active Rac1 becomes apparent in lamellipodia of mesenchymal cells. Loss of Rac1 function at trunk levels inhibited NC migration but did not prevent cell emigration that is associated with N-cadherin downregulation and G1/S transition. Furthermore, inhibition of Rho stimulated premature Rac1 activity and consequent formation of lamellipodia, leading to NC migration. To examine whether timely migration influences cell fate, Rac1 activity was transiently inhibited to delay dispersion of early NC cells that generate neural derivatives, and its activity was restored by the time of melanoblast migration. Even if confronted with a melanocytic environment, late-dispersing progenitors colonized sensory ganglia where they generated neurons and glia. CONCLUSIONS: In the context of crest delamination and migration, activities of Rho and Rac are differential, sequential, and antagonistic. Furthermore, transient inhibition of Rac1 that delays the onset of crest dispersion raises the possibility that the fate of trunk neural progenitors might be restricted prior to migration.

A negative modulatory role for rho and rho-associated kinase signaling in delamination of neural crest cells.

BACKGROUND: Neural crest progenitors arise as epithelial cells and then undergo a process of epithelial to mesenchymal transition that precedes the generation of cellular motility and subsequent migration. We aim at understanding the underlying molecular network. Along this line, possible roles of Rho GTPases that act as molecular switches to control a variety of signal transduction pathways remain virtually unexplored, as are putative interactions between Rho proteins and additional known components of this cascade. RESULTS: We investigated the role of Rho/Rock signaling in neural crest delamination. Active RhoA and RhoB are expressed in the membrane of epithelial progenitors and are downregulated upon delamination. In vivo loss-of-function of RhoA or RhoB or of overall Rho signaling by C3 transferase enhanced and/or triggered premature crest delamination yet had no effect on cell specification. Consistently, treatment of explanted neural primordia with membrane-permeable C3 or with the Rock inhibitor Y27632 both accelerated and enhanced crest emigration without affecting cell proliferation. These treatments altered neural crest morphology by reducing stress fibers, focal adhesions and downregulating membrane-bound N-cadherin. Reciprocally, activation of endogenous Rho by lysophosphatidic acid inhibited emigration while enhancing the above. Since delamination is triggered by BMP and requires G1/S transition, we examined their relationship with Rho. Blocking Rho/Rock function rescued crest emigration upon treatment with noggin or with the G1/S inhibitor mimosine. In the latter condition, cells emigrated while arrested at G1. Conversely, BMP4 was unable to rescue cell emigration when endogenous Rho activity was enhanced by lysophosphatidic acid. CONCLUSION: Rho-GTPases, through Rock, act downstream of BMP and of G1/S transition to negatively regulate crest delamination by modifying cytoskeleton assembly and intercellular adhesion.

Development and validation of a Patient-Reported Oral Mucositis Symptom (PROMS) scale.

BACKGROUND AND OBJECTIVE: Oral mucositis, a painful condition with potentially life-threatening sequelae, often develops in association with allogeneic bone marrow transplantation. This condition has an adverse impact on the oral-health-related quality of life of patients undergoing marrow transplantation therapy. The purpose of this study was to create and validate a Patient-Reported Oral Mucositis Symptom (PROMS) scale. This scale allows evaluation of symptoms of oral mucositis that threaten quality of life. MATERIALS AND METHODS: The PROMS scale was compared with previously validated tools measuring quality of life (Functional Assessment of Cancer Therapy--Bone Marrow Transplant), symptoms of depression (Center for Epidemiologic Studies Depression Scale), psychological well-being (Affect Balance Scale) and stressful life events, as well as an objective, clinician-rated assessment of oral mucositis (Visual Analogue Scale--Oral Mucositis Assessment Scale). Thirty-four patients who were to undergo allogeneic bone marrow transplantation at Princess Margaret Hospital in Toronto, Ontario, were enrolled in this validation study. RESULTS: The PROMS scale had high internal reliability, as well as good convergent and discriminant validity relative to subjective measures of well-being. Longitudinal assessments showed that changes in PROMS scores were strongly correlated with changes in clinical assessment of oral mucositis over the first 2 weeks after transplantation, when the onset of oral mucositis typically occurs and the lesions are most severe. CONCLUSIONS: Oral mucositis in patients who have undergone bone marrow transplantation can be quantified reliably with the easily administered PROMS scale. The PROMSscale provides a valid measure of the impact of oral mucositis on the oral-health-related quality of life of patients affected by this malady.

Antagonistic roles of full-length N-cadherin and its soluble BMP cleavage product in neural crest delamination.

During neural crest ontogeny, an epithelial to mesenchymal transition is necessary for cell emigration from the dorsal neural tube. This process is likely to involve a network of gene activities, which remain largely unexplored. We demonstrate that N-cadherin inhibits the onset of crest delamination both by a cell adhesion-dependent mechanism and by repressing canonical Wnt signaling previously found to be necessary for crest delamination by acting downstream of BMP4. Furthermore, N-cadherin protein, but not mRNA, is normally downregulated along the dorsal tube in association with the onset of crest delamination, and we find that this process is triggered by BMP4. BMP4 stimulates cleavage of N-cadherin into a soluble cytoplasmic fragment via an ADAM10-dependent mechanism. Intriguingly, when overexpressed, the cytoplasmic N-cadherin fragment translocates into the nucleus, stimulates cyclin D1 transcription and crest delamination, while enhancing transcription of beta-catenin. CTF2 also rescues the mesenchymal phenotype of crest cells in ADAM10-inhibited neural primordia. Hence, by promoting its cleavage, BMP4 converts N-cadherin inhibition into an activity that is likely to participate, along with canonical Wnt signaling, in the stimulation of neural crest emigration.