Vegfa signaling regulates diverse artery/vein formation in vertebrate vasculatures

Trace-level Gabapentin can induce cardiovascular developmental toxicity through apoptosis in zebrafish larvae

Gabapentin (GBP), an antiepileptic drug to treat epilepsy and neuropathic pain, has become an emerging pollutant in aquatic environments. Previous results suggested that GBP can cause a potential toxicity on the heart development of zebrafish but its cardiovascular effects are still not clear. In the current study, zebrafish embryos were exposed to GBP at environmental relevant concentrations (0, 0.1, 10 and 1000 μg/L) to assess its impact on cardiovascular systems during the early life stage of zebrafish. GBP exposure induced an increase in heartbeat rate and blood flow. The development of blood vessels was also affected with the vascular width significantly decreased at 10 μg/L and higher concentration of GBP. GBP exposure led to an abnormal vascular development by inhibiting the expression of relevant genes (flk1, vegfr-3, gata1, vegfα, and vegfr-2). Furthermore, GBP at 0.1 μg/L elevated the levels of reactive oxygen species and antioxidant enzyme. The vascular cell apoptosis was promoted through genes like p53, bad, and bcl2. However, these adverse effects were reversible with the antioxidant N-acetyl-L-cysteine, highlighting the crucial role of oxidative damage in GBP induced vascular toxicity. This research offers new perspectives on the adverse outcome pathways of antiepileptic drugs in non-target aquatic organisms.

Avermectin induced vascular damage in zebrafish larvae: association with mitochondria-mediated apoptosis and VEGF/Notch signaling pathway

Avermectin is a highly effective insecticide that has been widely used in agriculture since the 1990s. In recent years, the safety of avermectin for non-target organisms has received much attention. The vasculature is important organs in the body and participate in the composition of other organs. However, studies on the vascular safety of avermectin are lacking. The vasculature of zebrafish larvae is characterized by ease of observation and it is a commonly used model for vascular studies. Therefore, zebrafish larvae were used to explore the potential risk of avermectin on the vasculature. The results showed that avermectin induced vascular damage throughout the body of zebrafish larvae, including the head, eyes, intestine, somite, tail and other vasculature. The main forms of damage are reduction in vascular diameter, vascular area and vascular abundance. Meanwhile, avermectin induced a decrease in the number of endothelial cells and apoptosis within the vasculature. In addition, vascular damage may be related to impairment of mitochondrial function and mitochondria-mediated apoptosis. Finally, exploration of the molecular mechanisms revealed abnormal alterations in the expression of genes related to the VEGF/Notch signaling pathway. Therefore, the VEGF/Notch signaling pathway may be an important mechanism for avermectin-induced vascular damage in zebrafish larvae. This study demonstrates the vascular toxicity of avermectin in zebrafish larvae and reveals the possible molecular mechanism, which would hopefully draw more attention to the safety of avermectin in non-target organisms.

Cerebral Vascular Toxicity after Developmental Exposure to Arsenic (As) and Lead (Pb) Mixtures

Arsenic (As) and lead (Pb) are environmental pollutants found in common sites linked to similar adverse health effects. This study determined driving factors of neurotoxicity on the developing cerebral vasculature with As and Pb mixture exposures. Cerebral vascular toxicity was evaluated at mixture concentrations of As and Pb representing human exposures levels (10 or 100 parts per billion; ppb; µg/L) in developing zebrafish by assessing behavior, morphology, and gene expression. In the visual motor response assay, hyperactivity was observed in all three outcomes in dark phases in larvae with exposure (1-120 h post fertilization, hpf) to 10 ppb As, 10 ppb Pb, or 10 ppb mix treatment. Time spent moving exhibited hyperactivity in dark phases for 100 ppb As and 100 ppb mix treatment groups only. A decreased brain length and ratio of brain length to total length in the 10 ppb mix group was measured with no alterations in other treatment groups or other endpoints (i.e., total larval length, head length, or head width). Alternatively, measurements of cerebral vasculature in the midbrain and cerebellum uncovered decreased total vascularization at 72 hpf in all treatment groups in the mesencephalon and in all treatment groups, except the 100 ppb Pb and 10 ppb As groups, in the cerebellum. In addition, decreased sprouting and branching occurred in the mesencephalon, while only decreased branching was measured in the cerebellum. The 10 ppb Pb group showed several cerebral vasculature modifications that were aligned with a specific gene expression alteration pattern different from other treatment groups. Additionally, the 100 ppb As group drove gene alterations, along with several other endpoints, for changes observed in the 100 ppb mix treatment group. Perturbations assessed in this study displayed non-linear concentration-responses, which are important to consider in environmental health outcomes for As and Pb neurotoxicity.

Downregulation of VEGFA accelerates AGEs-mediated nucleus pulposus degeneration through inhibiting protective mitophagy in high glucose environments

Intervertebral disc degeneration (IVDD) contributes largely to low back pain. Recent studies have highlighted the exacerbating role of diabetes mellitus (DM) in IVDD, mainly due to the influence of hyperglycemia (HG) or the accumulation of advanced glycation end products (AGEs). Vascular endothelial growth factor A (VEGFA) newly assumed a distinct impact in nonvascular tissues through mitophagy regulation. However, the combined actions of HG and AGEs on IVDD and the involved role of VEGFA remain unclear. We confirmed the potential relation between VEGFA and DM through bioinformatics and biological specimen detection. Then we observed that AGEs induced nucleus pulposus (NP) cell degeneration by upregulating cellular reactive oxygen species (ROS), and HG further aggravated ROS level through breaking AGEs-induced protective mitophagy. Furthermore, this adverse effect could be strengthened by VEGFA knockdown. Importantly, we identified that the regulation of VEGFA and mitophagy were vital mechanisms in AGEs-HG-induced NP cell degeneration through Parkin/Akt/mTOR and AMPK/mTOR pathway. Additionally, VEGFA overexpression through local injection with lentivirus carrying VEGFA plasmids significantly alleviated NP degeneration and IVDD in STZ-induced diabetes and puncture rat models. In conclusion, the findings first confirmed that VEGFA protects against AGEs-HG-induced IVDD, which may represent a therapeutic strategy for DM-related IVDD.

Vascular Endothelial Growth Factor A (VEGFA) Regulates Hepatic Lipid and Glycogen Metabolism in Schizothorax prenanti

Vascular endothelial growth factor A (VEGFA) plays important roles in angiogenesis, inflammatory response as well as energy metabolism in mammals. However, its effect on glycolipid metabolism in fish has not been reported. In this study, we cloned and characterized the vegfa gene of Schizothorax prenanti (S. prenanti). vegfa expression was significantly higher in liver and muscle than that in other tissues. Then, the VEGFA recombinant protein was expressed in Escherichia coli and obtained after purification. VEGFA i.p. injection significantly increased the serum glucose and TG content compared with the control group. Moreover, VEGFA protein aggravated the glycogen and lipid deposition in the liver of S. prenanti. In addition, we found that VEGFA treatment increased hepatocyte glycogen and lipid droplet content and increased the levels of pAMPKα (T172). Furthermore, AMPKα inhibition attenuated the ability of VEGFA to induce TG and glycogen accumulation. These results demonstrate that VEGFA regulates hepatic lipid and glycogen metabolism through AMPKα in S. prenanti, which may contribute to a better understanding of VEGFA functions in the glycolipid metabolism of fish.

VEGF signaling governs the initiation of biliary-mediated liver regeneration through the PI3K-mTORC1 axis

Biliary epithelial cells (BECs) are a potential source to repair the damaged liver when hepatocyte proliferation is compromised. Promotion of BEC-to-hepatocyte transdifferentiation could be beneficial to the clinical therapeutics of patients with end-stage liver diseases. However, mechanisms underlying the initiation of BEC transdifferentiation remain largely unknown. Here, we show that upon extreme hepatocyte injury, vegfaa and vegfr2/kdrl are notably induced in hepatic stellate cells and BECs, respectively. Pharmacological and genetic inactivation of vascular endothelial growth factor (VEGF) signaling would disrupt BEC dedifferentiation and proliferation, thus restraining hepatocyte regeneration. Mechanically, VEGF signaling regulates the activation of the PI3K-mammalian target of rapamycin complex 1 (mTORC1) axis, which is essential for BEC-to-hepatocyte transdifferentiation. In mice, VEGF signaling exerts conserved roles in oval cell activation and BEC-to-hepatocyte differentiation. Taken together, this study shows VEGF signaling as an initiator of biliary-mediated liver regeneration through activating the PI3K-mTORC1 axis. Modulation of VEGF signaling in BECs could be a therapeutic approach for patients with end-stage liver diseases.

Bisphenol S induces cardiovascular toxicity by disturbing the development of the common cardinal vein and myocardial contractility in zebrafish embryos

Bisphenol S (BPS) has been widely used as a substitute for bisphenol A in industrial manufacturing. However, the safety of BPS is controversial, and the mechanism by which BPS exerts cardiovascular toxicity remains unclear. In this study, zebrafish embryos, including wild-type zebrafish and transgenic (flk1:eGFP), (gata1:DsRed) and (cmlc2:eGFP) zebrafish at 2 h postfertilization (hpf), were exposed to BPS at concentrations of 1, 10 and 100 μg/L for 24, 48 and 72 h, respectively. The data showed that BPS accelerated the expansion of the common cardinal vein and inhibited lumen formation between 24 hpf and 72 hpf. Moreover, low-dose BPS disturbed cardiac muscle contraction by breaking the calcium balance in cardiac muscle cells according to the RNA-seq results. As a consequence, increased heart rate and irregular blood circulation were observed in the BPS treatment groups. This result suggested that BPS at environmental relevant concentrations caused cardiovascular toxicity during the development of zebrafish embryos, possibly being an important inducer of cardiovascular injury later in life. These findings provide insight into the rational and safe application of BPS.

Myogenic regulatory factors Myod and Myf5 are required for dorsal aorta formation and angiogenic sprouting

The vertebrate embryonic midline vasculature forms in close proximity to the developing skeletal muscle, which originates in the somites. Angioblasts migrate from bilateral positions along the ventral edge of the somites until they meet at the midline, where they sort and differentiate into the dorsal aorta and the cardinal vein. This migration occurs at the same time that myoblasts in the somites are beginning to differentiate into skeletal muscle, a process which requires the activity of the basic helix loop helix (bHLH) transcription factors Myod and Myf5. Here we examined vasculature formation in myod and myf5 mutant zebrafish. In the absence of skeletal myogenesis, angioblasts migrate normally to the midline but form only the cardinal vein and not the dorsal aorta. The phenotype is due to the failure to activate vascular endothelial growth factor ligand vegfaa expression in the somites, which in turn is required in the adjacent angioblasts for dorsal aorta specification. Myod and Myf5 cooperate with Hedgehog signaling to activate and later maintain vegfaa expression in the medial somites, which is required for angiogenic sprouting from the dorsal aorta. Our work reveals that the early embryonic skeletal musculature in teleosts evolved to organize the midline vasculature during development.

Zebrafish mutants in vegfab can affect endothelial cell proliferation without altering ERK phosphorylation and are phenocopied by loss of PI3K signaling

The formation of appropriately patterned blood vessel networks requires endothelial cell migration and proliferation. Signaling through the Vascular Endothelial Growth Factor A (VEGFA) pathway is instrumental in coordinating these processes. mRNA splicing generates short (diffusible) and long (extracellular matrix bound) Vegfa isoforms. The differences between these isoforms in controlling cellular functions are not understood. In zebrafish, vegfaa generates short and long isoforms, while vegfab only generates long isoforms. We found that mutations in vegfaa had an impact on endothelial cell (EC) migration and proliferation. Surprisingly, mutations in vegfab more strongly affected EC proliferation in distinct blood vessels, such as intersegmental blood vessels in the zebrafish trunk and central arteries in the head. Analysis of downstream signaling pathways revealed no change in MAPK (ERK) activation, while inhibiting PI3 kinase signaling phenocopied vegfab mutant phenotypes in affected blood vessels. Together, these results suggest that extracellular matrix bound Vegfa might act through PI3K signaling to control EC proliferation in a distinct set of blood vessels during angiogenesis.

VPS28 regulates brain vasculature by controlling neuronal VEGF trafficking through extracellular vesicle secretion

Extracellular vesicles (EVs) participate in intercellular communication and contribute to the angiogenesis. However, the understanding of the mechanisms underlying EVs secretion by neurons and their action on the vascular system of the central nervous system (CNS) remain rudimentary. Here, we show that vacuolar protein sorting 28 (Vps28) is essential for the sprouting of brain central arteries (CtAs) and for the integrity of blood-brain barrier (BBB) in zebrafish. Disruption of neuron-enriched Vps28 significantly decreased EVs secretion by regulating the formation of intracellular multivesicular bodies (MVBs). EVs derived from zebrafish embryos or mouse cortical neurons partially rescued the brain vasculature defect and brain leakage. Further investigations revealed that neuronal EVs containing vascular endothelial growth factor A (VEGF-A) are key regulators in neurovascular communication. Our results indicate that Vps28 acts as an intercellular endosomal regulator mediating the secretion of neuronal EVs, which in turn communicate with endothelial cells to mediate angiogenesis through VEGF-A trafficking.

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Vps28 is highly expressed in neurons and involved in the secretion of neuronal EVs

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Vps28, as a subunit of ESCRT-1 complexes, participates in the formation of MVB

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Vps28 plays an important role in VEGFA transport and promotes neurovascular communication

Selective and competitive functions of the AAR and UPR pathways in stress-induced angiogenesis

The amino acid response (AAR) and unfolded protein response (UPR) pathways converge on eIF2α phosphorylation, which is catalyzed by Gcn2 and Perk, respectively, under different stresses. This close interconnection makes it difficult to specify different functions of AAR and UPR. Here, we generated a zebrafish model in which loss of threonyl-tRNA synthetase (Tars) induces angiogenesis dependent on Tars aminoacylation activity. Comparative transcriptome analysis of the tars-mutant and wild-type embryos with/without Gcn2- or Perk-inhibition reveals that only Gcn2-mediated AAR is activated in the tars-mutants, whereas Perk functions predominantly in normal development. Mechanistic analysis shows that, while a considerable amount of eIF2α is normally phosphorylated by Perk, the loss of Tars causes an accumulation of uncharged tRNA^Thr, which in turn activates Gcn2, leading to phosphorylation of an extra amount of eIF2α. The partial switchover of kinases for eIF2α largely overwhelms the functions of Perk in normal development. Interestingly, although inhibition of Gcn2 and Perk in this stress condition both can reduce the eIF2α phosphorylation levels, their functional consequences in the regulation of target genes and in the rescue of the angiogenic phenotypes are dramatically different. Indeed, genetic and pharmacological manipulations of these pathways validate that the Gcn2-mediated AAR, but not the Perk-mediated UPR, is required for tars-deficiency induced angiogenesis. Thus, the interconnected AAR and UPR pathways differentially regulate angiogenesis through selective functions and mutual competitions, reflecting the specificity and efficiency of multiple stress response pathways that evolve integrally to enable an organism to sense/respond precisely to various types of stresses.

Isoflucypram cardiovascular toxicity in zebrafish (Danio rerio)

Isoflucypram belongs to the new generation of succinate dehydrogenase inhibitor (SDHI) fungicides that are commonly used in crop fungal disease control. Evidence indicates that isoflucypram poses a potential risk to aquatic organisms. However, the effects of isoflucypram during early embryogenesis are not fully understood. In the present study, zebrafish embryos were exposed to 0.025, 0.25, or 2.5 μM isoflucypram for three days. Isoflucypram caused severe developmental abnormalities (yolk sac edema, pericardial edema, and blood clotting clustering), hatching delay, and decreased heart rates in zebrafish. The expression levels of cardiac-specific genes (nkx2.5, myh7, myl7, and myh6) and erythropoiesis-related genes (gata1a, hbbe1, hbbe2, and alas2) were disrupted after isoflucypram exposure. Furthermore, enrichment analysis indicated that most of the differentially expressed genes (DEGs) were enriched in heart development or hemopoiesis processes. Overall, these findings suggest that exposure to isoflucypram is associated with developmental and cardiovascular toxicity in zebrafish.

Dhx15 regulates zebrafish definitive hematopoiesis through the unfolded protein response pathway

Gene alterations are recognized as important events in acute myeloid leukemia (AML) progression. Studies on hematopoiesis of altered genes contribute to a better understanding on their roles in AML progression. Our previous work reported a DEAH box helicase 15 (DHX15) R222G mutation in AML patients, and we showed DHX15 overexpression is associated with poor prognosis in AML patients. In this work, we further study the role of dhx15 in zebrafish developmental hematopoiesis by generating dhx15^−/− zebrafish using transcription activator‐like effector nuclease technology. Whole‐mount in situ hybridization (WISH) analysis showed hematopoietic stem/progenitor cells were dramatically perturbed when dhx15 was deleted. Immunofluorescence staining indicated inhibited hematopoietic stem/progenitor cell (HSPC) proliferation instead of accelerated apoptosis were detected in dhx15^−/− zebrafish. Furthermore, our data showed that HSPC defect is mediated through the unfolded protein response (UPR) pathway. DHX15 R222G mutation, a recurrent mutation identified in AML patients, displayed a compromised function in restoring HSPC failure in dhx15^−/−; Tg (hsp: DHX15 R222G) zebrafish. Collectively, this work revealed a vital role of dhx15 in the maintenance of definitive hematopoiesis in zebrafish through the unfolded protein respone pathway. The study of DHX15 and DHX15 R222G mutation could hold clinical significance for evaluating prognosis of AML patients with aberrant DHX15 expression.

Zebrafish scube1 and scube2 cooperate in promoting Vegfa signaling during embryonic vascularization

AIMS

The secreted and membrane-anchored SCUBE (signal peptide-CUB-EGF domain-containing proteins) gene family composed of 3 members was originally identified from endothelial cells (ECs). We recently showed that membrane SCUBE2 binds vascular endothelial growth factor A (VEGFA) and acts as a co-receptor for VEGF receptor 2 (VEGFR2) to modulate EC migration, proliferation and tube formation during postnatal and tumor angiogenesis. However, whether these SCUBE genes cooperate in modulating VEGF signaling during embryonic vascular development remains unknown.

METHODS AND RESULTS

To further dissect the genetic interactions of these scube genes, transcription activator-like effector nuclease-mediated genome editing was used to generate knockout (KO) alleles of each scube gene. No overt vascular phenotypes were seen in any single scube KO mutants because of compensation by other scube genes during zebrafish development. However, scube1 and scube2 double KO (DKO) severely impaired EC filopodia extensions, migration, and proliferation, thus disrupting proper vascular lumen formation during vasculogenesis and angiogenesis as well as development of the organ-specific intestinal vasculature. Further genetic, biochemical, and molecular analyses revealed that Scube1 and Scube2 might act cooperatively at the cell-surface receptor level to facilitate Vegfa signaling during zebrafish embryonic vascularization.

CONCLUSIONS

We showed for the first time that cooperation between scube1 and scube2 is critical for proper regulation of angiogenic cell behaviors and formation of functional vessels during zebrafish embryonic development.

TRANSLATIONAL PERSPECTIVE

Our studies indicate that targeting SCUBE1 and/or SCUBE2 on modulating VEGF signaling might provide potential therapeutic treatments or VEGF-mediated proliferative pathological vascular diseases.

l-Borneol Exerted the Neuroprotective Effect by Promoting Angiogenesis Coupled With Neurogenesis via Ang1-VEGF-BDNF Pathway

At present, Stroke is still one of the leading causes of population death worldwide and leads to disability. Traditional Chinese medicine plays an important role in the prevention or treatment of stroke. l-borneol, a traditional Chinese medicine, has been used in China to treat stroke for thousands of years. However, its mechanism of action is unclear. After cerebral ischemia, promoting angiogenesis after cerebral ischemia and providing nutrition for the infarct area is an important strategy to improve the damage in the ischemic area, but it is also essential to promote neurogenesis and replenish new neurons. Here, our research shows that l-borneol can significantly improve the neurological deficits of pMCAO model rats, reduce cerebral infarction, and improve the pathological damage of cerebral ischemia. and significantly increase serum level of Ang-1 and VEGF, and significantly decrease level of ACE and Tie2 to promote angiogenesis. PCR and WB showed the same results. Immunohistochemistry also showed that l-borneol can increase the number of CD34 positive cells, further verifying that l-borneol can play a neuroprotective effect by promoting angiogenesis after cerebral ischemia injury. In addition, l-borneol can significantly promote the expression level of VEGF, BDNF and inhibit the expression levels of TGF-β1 and MMP9 to promote neurogenesis. The above suggests that l-borneol can promote angiogenesis coupled neurogenesis by regulating Ang1-VEGF-BDNF to play a neuroprotective effect. Molecular docking also shows that l-borneol has a very high binding rate with the above target, which further confirmed the target of l-borneol to improve cerebral ischemic injury. These results provide strong evidence for the treatment of cerebral ischemia with l-borneol and provide reference for future research.

Association between Single Nucleotide Polymorphisms in Cardiovascular Developmental Critical Genes and Hypertension: A Propensity Score Matching Analysis

Cardiovascular development critical genes are key determinants in cardiovascular diseases. We hypothesize that SNPs in these genes may play critical roles in the development of hypertension. Therefore, we enrolled 516 paired hypertension patients and controls in a total of 2,742 subjects in a cross-sectional population study by the propensity score matching (PSM) method. Twenty-one SNPs from 5 cardiovascular developmental related genes were detected by the improved multiplex ligase detection reaction (iMLDR) method. Conditioned logistic regression under three different genetic models, namely, additive model, dominant model, and recessive model, was performed. The odds ratio (ORs) and 95% confidence intervals (95% CIs) were used to estimate the associations of SNPs with hypertension. We found that the distribution of genotypes at rs833061, rs3025010, and rs699947 within the VEGFA gene and the distribution of alleles at rs3025010 in hypertension subjects were different from those in controls. Both rs833061 and rs3025010 were associated with hypertension in crude models, but only rs3025010 remains associated with hypertension after adjusting with confounding factors in the additive model and the dominant model. We also found that hypertension subjects with C/T and C/C genotypes at rs3025010 had lower SBP and DBP levels. In addition, rs3025010 could interact with rs6784267 within the CCM3 gene in the association. In conclusion, our findings suggest that rs3025010 may play a role in the pathogenesis of hypertension, which may be a potential target for individualized prevention and treatment of hypertension.

Endothelial CDS2 deficiency causes VEGFA-mediated vascular regression and tumor inhibition

The response of endothelial cells to signaling stimulation is critical for vascular morphogenesis, homeostasis and function. Vascular endothelial growth factor-a (VEGFA) has been commonly recognized as a pro-angiogenic factor in vertebrate developmental, physiological and pathological conditions for decades. Here we report a novel finding that genetic ablation of CDP-diacylglycerol synthetase-2 (CDS2), a metabolic enzyme that controls phosphoinositide recycling, switches the output of VEGFA signaling from promoting angiogenesis to unexpectedly inducing vessel regression. Live imaging analysis uncovered the presence of reverse migration of the angiogenic endothelium in cds2 mutant zebrafish upon VEGFA stimulation, and endothelium regression also occurred in postnatal retina and implanted tumor models in mice. In tumor models, CDS2 deficiency enhanced the level of tumor-secreted VEGFA, which in-turn trapped tumors into a VEGFA-induced vessel regression situation, leading to suppression of tumor growth. Mechanistically, VEGFA stimulation reduced phosphatidylinositol (4,5)-bisphosphate (PIP2) availability in the absence of CDS2-controlled-phosphoinositide metabolism, subsequently causing phosphatidylinositol (3,4,5)-triphosphate (PIP3) deficiency and FOXO1 activation to trigger regression of CDS2-null endothelium. Thus, our data indicate that the effect of VEGFA on vasculature is context-dependent and can be converted from angiogenesis to vascular regression.

Atypical Chemokine Receptor 3 Generates Guidance Cues for CXCL12-Mediated Endothelial Cell Migration

Chemokine receptor CXCR4, its ligand stromal cell-derived factor-1 (CXCL12) and the decoy receptor atypical chemokine receptor 3 (ACKR3, also named CXCR7), are involved in the guidance of migrating cells in different anatomical districts. Here, we investigated the role of the ACKR3 zebrafish ortholog ackr3b in the vascularization process during embryonic development. Bioinformatics and functional analyses confirmed that ackr3b is a CXCL12-binding ortholog of human ACKR3. ackr3b is transcribed in the endoderm of zebrafish embryos during epiboly and is expressed in a wide range of tissues during somitogenesis, including central nervous system and somites. Between 18 somite and 26 h-post fertilization stages, the broad somitic expression of ackr3b becomes restricted to the basal part of the somites. After ackr3b knockdown, intersomitic vessels (ISVs) lose the correct direction of migration and are characterized by the presence of aberrant sprouts and ectopic filopodia protrusions, showing downregulation of the tip/stalk cell marker hlx1. In addition, ackr3b morphants show significant alterations of lateral dorsal aortae formation. In keeping with a role for ackr3b in endothelial cell guidance, CXCL12 gradient generated by ACKR3 expression in CHO cell transfectants guides human endothelial cell migration in an in vitro cell co-culture chemotaxis assay. Our results demonstrate that ackr3b plays a non-redundant role in the guidance of sprouting endothelial cells during vascular development in zebrafish. Moreover, ACKR3 scavenging activity generates guidance cues for the directional migration of CXCR4-expressing human endothelial cells in response to CXCL12.

GIPC proteins negatively modulate Plexind1 signaling during vascular development

Semaphorins (SEMAs) and their Plexin (PLXN) receptors are central regulators of metazoan cellular communication. SEMA-PLXND1 signaling plays important roles in cardiovascular, nervous, and immune system development, and cancer biology. However, little is known about the molecular mechanisms that modulate SEMA-PLXND1 signaling. As PLXND1 associates with GIPC family endocytic adaptors, we evaluated the requirement for the molecular determinants of their association and PLXND1's vascular role. Zebrafish that endogenously express a Plxnd1 receptor with a predicted impairment in GIPC binding exhibit low penetrance angiogenesis deficits and antiangiogenic drug hypersensitivity. Moreover, gipc mutant fish show angiogenic impairments that are ameliorated by reducing Plxnd1 signaling. Finally, GIPC depletion potentiates SEMA-PLXND1 signaling in cultured endothelial cells. These findings expand the vascular roles of GIPCs beyond those of the Vascular Endothelial Growth Factor (VEGF)-dependent, proangiogenic GIPC1-Neuropilin 1 complex, recasting GIPCs as negative modulators of antiangiogenic PLXND1 signaling and suggest that PLXND1 trafficking shapes vascular development.

Identifying the Growth Factors for Improving Neointestinal Regeneration in Rats through Transcriptome Analysis Using RNA-Seq Data

Using our novel surgical model of simultaneous intestinal adaptation "A" and neointestinal regeneration "N" conditions in individual rats to determine feasibility for research and clinical application, we further utilized next generation RNA sequencing (RNA-Seq) here in normal control tissue and both conditions ("A" and "N") across time to decipher transcriptome changes in neoregeneration and adaptation of intestinal tissue at weeks 1, 4, and 12. We also performed bioinformatics analyses to identify key growth factors for improving intestinal adaptation and neointestinal regeneration. Our analyses indicate several interesting phenomena. First, Gene Ontology and pathway analyses indicate that cell cycle and DNA replication processes are enhanced in week 1 "A"; however, in week 1 "N", many immune-related processes are involved. Second, we found some growth factors upregulated or downregulated especially in week 1 "N" versus "A". Third, based on each condition and time point versus normal control tissue, we found in week 1 "N" BMP2, BMP3, and NTF3 are significantly and specifically downregulated, indicating that the regenerative process may be inhibited in the absence of these growth factors. This study reveals complex growth factor regulation in small neointestinal regeneration and intestinal adaptation and provides potential applications in tissue engineering by introducing key growth factors identified here into the injury site.

Vegfa Impacts Early Myocardium Development in Zebrafish

Vascular endothelial growth factor A (Vegfa) signaling regulates cardiovascular development. However, the cellular mechanisms of Vegfa signaling in early cardiogenesis remain poorly understood. The present study aimed to understand the differential functions and mechanisms of Vegfa signaling in cardiac development. A loss-of-function approach was utilized to study the effect of Vegfa signaling in cardiogenesis. Both morphants and mutants for vegfaa display defects in cardiac looping and chamber formation, especially the ventricle. Vegfa regulates the heart morphogenesis in a dose-dependent manner. Furthermore, the initial fusion of the bilateral myocardium population is delayed rather than endocardium. The results demonstrate that Vegfa signaling plays a direct impact on myocardium fusion, indicating that it is the initial cause of the heart defects. The heart morphogenesis is regulated by Vegfa in a dose-dependent manner, and later endocardium defects may be secondary to impaired myocardium–endocardium crosstalk.