Zinc-finger transcriptional factor Sall1 induces angiogenesis by activation of the gene for VEGF-A

Site-specific genetic and functional signatures of aortic endothelial cells at aneurysm predilection sites in healthy and AngII ApoE-/- mice

Aortic aneurysm is characterized by a pathological dilation at specific predilection sites of the vessel and potentially results in life-threatening vascular rupture. Herein, we established a modified "Häutchen method" for the local isolation of endothelial cells (ECs) from mouse aorta to analyze their spatial heterogeneity and potential role in site-specific disease development. When we compared ECs from aneurysm predilection sites of healthy mice with adjacent control segments we found regulation of genes related to extracellular matrix remodeling, angiogenesis and inflammation, all pathways playing a critical role in aneurysm development. We also detected enhanced cortical stiffness of the endothelium at these sites. Gene expression of ECs from aneurysms of the AngII ApoE-/- model when compared to sham animals mimicked expression patterns from predilection sites of healthy animals. Thus, this work highlights a striking genetic and functional regional heterogeneity in aortic ECs of healthy mice, which defines the location of aortic aneurysm formation in disease.

Neutrophils facilitate the epicardial regenerative response after zebrafish heart injury

Despite extensive studies on endogenous heart regeneration within the past 20 years, the players involved in initiating early regeneration events are far from clear. Here, we assessed the function of neutrophils, the first-responder cells to tissue damage, during zebrafish heart regeneration. We detected rapid neutrophil mobilization to the injury site after ventricular amputation, peaking at 1-day post-amputation (dpa) and resolving by 3 dpa. Further analyses indicated neutrophil mobilization coincides with peak epicardial cell proliferation, and recruited neutrophils associated with activated, expanding epicardial cells at 1 dpa. Neutrophil depletion inhibited myocardial regeneration and significantly reduced epicardial cell expansion, proliferation, and activation. To explore the molecular mechanism of neutrophils on the epicardial regenerative response, we performed scRNA-seq analysis of 1 dpa neutrophils and identified enrichment of the FGF and MAPK/ERK signaling pathways. Pharmacological inhibition of FGF signaling indicated its' requirement for epicardial expansion, while neutrophil depletion blocked MAPK/ERK signaling activation in epicardial cells. Ligand-receptor analysis indicated the EGF ligand, hbegfa, is released from neutrophils and synergizes with other FGF and MAPK/ERK factors for induction of epicardial regeneration. Altogether, our studies revealed that neutrophils quickly motivate epicardial cells, which later accumulate at the injury site and contribute to heart regeneration.

SALL4 Oncogenic Function in Cancers: Mechanisms and Therapeutic Relevance

SALL4, a member of the SALL family, is an embryonic stem cell regulator involved in self-renewal and pluripotency. Recently, SALL4 overexpression was found in malignant cancers, including lung cancer, hepatocellular carcinoma, breast cancer, gastric cancer, colorectal cancer, osteosarcoma, acute myeloid leukemia, ovarian cancer, and glioma. This review updates recent advances of our knowledge of the biology of SALL4 with a focus on its mechanisms and regulatory functions in tumors and human hematopoiesis. SALL4 overexpression promotes proliferation, development, invasion, and migration in cancers through activation of the Wnt/β-catenin, PI3K/AKT, and Notch signaling pathways; expression of mitochondrial oxidative phosphorylation genes; and inhibition of the expression of the Bcl-2 family, caspase-related proteins, and death receptors. Additionally, SALL4 regulates tumor progression correlated with the immune microenvironment involved in the TNF family and gene expression through epigenetic mechanisms, consequently affecting hematopoiesis. Therefore, SALL4 plays a critical oncogenic role in gene transcription and tumor growth. However, there are still some scientific hypotheses to be tested regarding whether SALL4 is a therapeutic target, such as different tumor microenvironments and drug resistance. Thus, an in-depth understanding and study of the functions and mechanisms of SALL4 in cancer may help develop novel strategies for cancer therapy.

A pan-cancer study of spalt-like transcription factors 1/2/3/4 as therapeutic targets

Spalt-like transcription factors (SALLs) are evolutionarily conserved proteins that participate in embryonic development. Four members of the SALL family, SALL1, SALL2, SALL3, and SALL4, are involved in cellular apoptosis, angiogenesis, invasion, and metastasis of tumors. We used the TCGA pan-cancer data to conduct a comprehensive analysis of SALL genes. High heterogeneity in the expression of these genes was observed across various cancers, SALL1 and SALL2 were downregulated, whereas SALL4 was upregulated. Moreover, we verified that SALL4 was commonly associated with survival disadvantage, whereas others were linked to a better prognosis. In renal cancer, SALL1, SALL2, and SALL3 showed downregulation, suggesting that they acted as tumor suppressors. Furthermore, SALLs were associated with immune infiltrate subtypes, with a close association between different degrees of infiltration of stromal cells and immune cells. DNA and RNA analyses in different tumors suggested different degrees of negative or positive correlation with tumor stem cell-like features. Finally, we revealed that SALLs were related to cancer cell resistance. Our results highlight the necessity to further study each SALL gene as a separate entity in specific types of cancer. Although this article showed that SALLs could be promising targets for cancer therapy, it needs further studies to validate the findings.

Epigenetic Markers Are Associated With Differences in Isocyanate Biomarker Levels in Exposed Spray-Painters

Isocyanates are respiratory and skin sensitizers that are one of the main causes of occupational asthma globally. Genetic and epigenetic markers are associated with isocyanate-induced asthma and, before asthma develops, we have shown that genetic polymorphisms are associated with variation in plasma and urine biomarker levels in exposed workers. Inter-individual epigenetic variance may also have a significant role in the observed biomarker variability following isocyanate exposure. Therefore, we determined the percent methylation for CpG islands from DNA extracted from mononuclear blood cells of 24 male spray-painters exposed to 1,6-hexamethylene diisocyanate (HDI) monomer and HDI isocyanurate. Spray-painters’ personal inhalation and skin exposure to these compounds and the respective biomarker levels of 1,6-diaminohexane (HDA) and trisaminohexyl isocyanurate (TAHI) in their plasma and urine were measured during three repeated industrial hygiene monitoring visits. We controlled for inhalation exposure, skin exposure, age, smoking status, and ethnicity as covariates and performed an epigenome-wide association study (EWAS) using likelihood-ratio statistical modeling. We identified 38 CpG markers associated with differences in isocyanate biomarker levels (Bonferroni < 0.05). Annotations for these markers included 18 genes: ALG1, ANKRD11, C16orf89, CHD7, COL27A, FUZ, FZD9, HMGN1, KRT6A, LEPR, MAPK10, MED25, NOSIP, PKD1, SNX19, UNC13A, UROS, and ZFHX3. We explored the functions of the genes that have been published in the literature and used GeneMANIA to investigate gene ontologies and predicted protein-interaction networks. The protein functions of the predicted networks include keratinocyte migration, cell–cell adhesions, calcium transport, neurotransmitter release, nitric oxide production, and apoptosis regulation. Many of the protein pathway functions overlap with previous findings on genetic markers associated with variability both in isocyanate biomarker levels and asthma susceptibility, which suggests there are overlapping protein pathways that contribute to both isocyanate toxicokinetics and toxicodynamics. These predicted protein networks can inform future research on the mechanism of allergic airway sensitization by isocyanates and aid in the development of mitigation strategies to better protect worker health.

Influence of Genetic Variance on Biomarker Levels After Occupational Exposure to 1,6-Hexamethylene Diisocyanate Monomer and 1,6-Hexamethylene Diisocyanate Isocyanurate

We evaluated the impact of genetic variance on biomarker levels in a population of workers in the automotive repair and refinishing industry who were exposed to respiratory sensitizers 1,6-hexamethylene diisocyanate (HDI) monomer and one of its trimers, HDI isocyanurate. The exposures and respective urine and plasma biomarkers 1,6-diaminohexane (HDA) and trisaminohexyl isocyanurate (TAHI) were measured in 33 workers; and genome-wide microarrays (Affymetrix 6.0) were used to genotype the workers' single-nucleotide polymorphisms (SNPs). Linear mixed model analyses have indicated that interindividual variations in both inhalation and skin exposures influenced these biomarker levels. Using exposure values as covariates and a false discovery rate < 0.10 to assess statistical significance, we observed that seven SNPs were associated with HDA in plasma, five were associated with HDA in urine, none reached significance for TAHI in plasma, and eight were associated with TAHI levels in urine. The different genotypes for the 20 significant SNPs accounted for 4- to 16-fold changes observed in biomarker levels. Associated gene functions include transcription regulation, calcium ion transport, vascular morphogenesis, and transforming growth factor beta signaling pathway, which may impact toxicokinetics indirectly by altering inflammation levels. Additionally, in an expanded analysis using a minor allele cutoff of 0.05 instead of 0.10, there were biomarker-associated SNPs within three genes that have been associated with isocyanate-induced asthma: ALK, DOCK2, and LHPP. We demonstrate that genetic variance impacts the biomarker levels in workers exposed to HDI monomer and HDI isocyanurate and that genetics can be used to refine exposure predictions in small cohorts when quantitative personal exposure and biomarker measurements are included in the models.

Vascular Endothelial Growth Factor 165-Binding Heparan Sulfate Promotes Functional Recovery From Cerebral Ischemia

BACKGROUND AND PURPOSE

Although VEGF₁₆₅ (vascular endothelial growth factor-165) is able to enhance both angiogenesis and neurogenesis, it also increases vascular permeability through the blood-brain barrier. Heparan sulfate (HS) sugars play important roles in regulating VEGF bioactivity in the pericellular compartment. Here we asked whether an affinity-purified VEGF₁₆₅-binding HS (HS7) could augment endogenous VEGF activity during stroke recovery without affecting blood-brain barrier function.

METHODS

Both rat brain endothelial cell line 4 and primary rat neural progenitor cells were used to evaluate the potential angiogenic and neurogenic effects of HS7 in vitro. For in vivo experiments, male Sprague-Dawley rats were subjected to 100 minutes of transient focal cerebral ischemia, then treated after 4 days with either PBS or HS7. One week later, infarct volume, behavioral sequelae, immunohistochemical markers of angiogenesis and neural stem cell proliferation were assessed.

RESULTS

HS7 significantly enhanced VEGF₁₆₅-mediated angiogenesis in rat brain endothelial cell line 4 brain endothelial cells, and increased the proliferation and differentiation of primary neural progenitor cells, both via the VEGFR2 (vascular endothelial growth factor receptor 2) pathway. Intracerebroventricular injection of HS7 improved neurological outcome in ischemic rats without changing infarct volumes. Immunostaining of the compromised cerebrum demonstrated increases in collagen IV/Ki67 and nestin/Ki67 after HS7 exposure, consistent with its ability to promote angiogenesis and neurogenesis, without compromising blood-brain barrier integrity.

CONCLUSIONS

A VEGF-activating glycosaminoglycan sugar, by itself, is able to enhance endogenous VEGF₁₆₅ activity during the post-ischemic recovery phase of stroke.

Prophylactic Chronic Zinc Administration Increases Neuroinflammation in a Hypoxia-Ischemia Model

Acute and subacute administration of zinc exert neuroprotective effects in hypoxia-ischemia animal models; yet the effect of chronic administration of zinc still remains unknown. We addressed this issue by injecting zinc at a tolerable dose (0.5 mg/kg weight, i.p.) for 14 days before common carotid artery occlusion (CCAO) in a rat. After CCAO, the level of zinc was measured by atomic absorption spectrophotometry, nitrites were determined by Griess method, lipoperoxidation was measured by Gerard-Monnier assay, and mRNA expression of 84 genes coding for cytokines, chemokines, and their receptors was measured by qRT-PCR, whereas nitrotyrosine, chemokines, and their receptors were assessed by ELISA and histopathological changes in the temporoparietal cortex-hippocampus at different time points. Long-term memory was evaluated using Morris water maze. Following CCAO, a significant increase in nitrosative stress, inflammatory chemokines/receptors, and cell death was observed after 8 h, and a 2.5-fold increase in zinc levels was detected after 7 days. Although CXCL12 and FGF2 protein levels were significantly increased, the long-term memory was impaired 12 days after reperfusion in the Zn+CCAO group. Our data suggest that the chronic administration of zinc at tolerable doses causes nitrosative stress, toxic zinc accumulation, and neuroinflammation, which might account for the neuronal death and cerebral dysfunction after CCAO.

Infant sex-specific placental cadmium and DNA methylation associations

BACKGROUND

Recent evidence suggests that maternal cadmium (Cd) burden and fetal growth associations may vary by fetal sex. However, mechanisms contributing to these differences are unknown.

OBJECTIVES

Among 24 maternal-infant pairs, we investigated infant sex-specific associations between placental Cd and placental genome-wide DNA methylation.

METHODS

We used ANOVA models to examine sex-stratified associations of placental Cd (dichotomized into high/low Cd using sex-specific Cd median cutoffs) with DNA methylation at each cytosine-phosphate-guanine site or region. Statistical significance was defined using a false discovery rate cutoff (<0.10).

RESULTS

Medians of placental Cd among females and males were 5 and 2 ng/g, respectively. Among females, three sites (near ADP-ribosylation factor-like 9 (ARL9), siah E3 ubiquitin protein ligase family member 3 (SIAH3), and heparin sulfate (glucosamine) 3-O-sulfotransferase 4 (HS3ST4) and one region on chromosome 7 (including carnitine O-octanoyltransferase (CROT) and TP5S target 1 (TP53TG1)) were hypomethylated in high Cd placentas. Among males, high placental Cd was associated with methylation of three sites, two (hypomethylated) near MDS1 and EVI1 complex locus (MECOM) and one (hypermethylated) near spalt-like transcription factor 1 (SALL1), and two regions (both hypomethylated, one on chromosome 3 including MECOM and another on chromosome 8 including rho guanine nucleotide exchange factor (GEF) 10 (ARHGEF10). Differentially methylated sites were at or close to transcription start sites of genes involved in cell damage response (SIAH3, HS3ST4, TP53TG1) in females and cell differentiation, angiogenesis and organ development (MECOM, SALL1) in males.

CONCLUSIONS

Our preliminary study supports infant sex-specific placental Cd-DNA methylation associations, possibly accounting for previously reported differences in Cd-fetal growth associations across fetal sex. Larger studies are needed to replicate and extend these findings. Such investigations may further our understanding of epigenetic mechanisms underlying maternal Cd burden with suboptimal fetal growth associations.

Sall1 regulates embryonic stem cell differentiation in association with nanog

Sall1 is a multi-zinc finger transcription factor that regulates kidney organogenesis. It is considered to be a transcriptional repressor, preferentially localized on heterochromatin. Mutations or deletions of the human SALL1 gene are associated with the Townes-Brocks syndrome. Despite its high expression, no function was yet assigned for Sall1 in embryonic stem (ES) cells. In the present study, we show that Sall1 is expressed in a differentiation-dependent manner and physically interacts with Nanog and Sox2, two components of the core pluripotency network. Genome-wide mapping of Sall1-binding loci has identified 591 genes, 80% of which are also targeted by Nanog. A large proportion of these genes are related to self-renewal and differentiation. Sall1 positively regulates and synergizes with Nanog for gene transcriptional regulation. In addition, our data show that Sall1 suppresses the ectodermal and mesodermal differentiation. Specifically, the induction of the gastrulation markers T brachyury, Goosecoid, and Dkk1 and the neuroectodermal markers Otx2 and Hand1 was inhibited by Sall1 overexpression during embryoid body differentiation. These data demonstrate a novel role for Sall1 as a member of the transcriptional network that regulates stem cell pluripotency.