The manganese transporter SLC39A8 links alkaline ceramidase 1 to inflammatory bowel disease.

The metal ion transporter SLC39A8 is associated with physiological traits and diseases, including blood manganese (Mn) levels and inflammatory bowel diseases (IBD). The mechanisms by which SLC39A8 controls Mn homeostasis and epithelial integrity remain elusive. Here, we generate Slc39a8 intestinal epithelial cell-specific-knockout (Slc39a8-IEC KO) mice, which display markedly decreased Mn levels in blood and most organs. Radiotracer studies reveal impaired intestinal absorption of dietary Mn in Slc39a8-IEC KO mice. SLC39A8 is localized to the apical membrane and mediates 54Mn uptake in intestinal organoid monolayer cultures. Unbiased transcriptomic analysis identifies alkaline ceramidase 1 (ACER1), a key enzyme in sphingolipid metabolism, as a potential therapeutic target for SLC39A8-associated IBDs. Importantly, treatment with an ACER1 inhibitor attenuates colitis in Slc39a8-IEC KO mice by remedying barrier dysfunction. Our results highlight the essential roles of SLC39A8 in intestinal Mn absorption and epithelial integrity and offer a therapeutic target for IBD associated with impaired Mn homeostasis.

The Hydrophilic Metabolite UMP Alleviates Obesity Traits through a HIF2α-ACER2-Ceramide Signaling Axis.

Metabolic abnormalities contribute to the pathogenesis of obesity and its complications. Yet, the understanding of the interactions between critical metabolic pathways that underlie obesity remains to be improved, in part owing to the lack of comprehensive metabolomics studies that reconcile data from both hydrophilic and lipophilic metabolome analyses that can lead to the identification and characterization of key signaling networks. Here, the study conducts a comprehensive metabolomics analysis, surveying lipids and hydrophilic metabolites of the plasma and omental adipose tissue of obese individuals and the plasma and epididymal adipose tissue of mice. Through these approaches, it is found that a significant accumulation of ceramide due to inhibited sphingolipid catabolism, while a significant reduction in the levels of uridine monophosphate (UMP), is critical to pyrimidine biosynthesis. Further, it is found that UMP administration restores sphingolipid homeostasis and can reduce obesity in mice by reversing obesity-induced inhibition of adipocyte hypoxia inducible factor 2a (Hif2α) and its target gene alkaline ceramidase 2 (Acer2), so as to promote ceramide catabolism and alleviate its accumulation within cells. Using adipose tissue Hif2α-specific knockout mice, the study further demonstrates that the presence of UMP can alleviate obesity through a HIF2α-ACER2-ceramide pathway, which can be a new signaling axis for obesity improvement.

Exosomal miR-125b-5p derived from adipose-derived mesenchymal stem cells enhance diabetic hindlimb ischemia repair via targeting alkaline ceramidase 2.

INTRODUCTION: Ischemic diseases caused by diabetes continue to pose a major health challenge and effective treatments are in high demand. Mesenchymal stem cells (MSCs) derived exosomes have aroused broad attention as a cell-free treatment for ischemic diseases. However, the efficacy of exosomes from adipose-derived mesenchymal stem cells (ADSC-Exos) in treating diabetic lower limb ischemic injury remains unclear. METHODS: Exosomes were isolated from ADSCs culture supernatants by differential ultracentrifugation and their effect on C2C12 cells and HUVECs was assessed by EdU, Transwell, and in vitro tube formation assays separately. The recovery of limb function after ADSC-Exos treatment was evaluated by Laser-Doppler perfusion imaging, limb function score, and histological analysis. Subsequently, miRNA sequencing and rescue experiments were performed to figure out the responsible miRNA for the protective role of ADSC-Exos on diabetic hindlimb ischemic injury. Finally, the direct target of miRNA in C2C12 cells was confirmed by bioinformatic analysis and dual-luciferase report gene assay. RESULTS: ADSC-Exos have the potential to promote proliferation and migration of C2C12 cells and to promote HUVECs angiogenesis. In vivo experiments have shown that ADSC-Exos can protect ischemic skeletal muscle, promote the repair of muscle injury, and accelerate vascular regeneration. Combined with bioinformatics analysis, miR-125b-5p may be a key molecule in this process. Transfer of miR-125b-5p into C2C12 cells was able to promote cell proliferation and migration by suppressing ACER2 overexpression. CONCLUSION: The findings revealed that miR-125b-5p derived from ADSC-Exos may play a critical role in ischemic muscle reparation by targeting ACER2. In conclusion, our study may provide new insights into the potential of ADSC-Exos as a treatment option for diabetic lower limb ischemia.

miR-196a-5p Correlates with Chronic Atrophic Gastritis Progression to Gastric Cancer and Induces Malignant Biological Behaviors of Gastric Cancer Cells by Targeting ACER2.

BACKGROUND: As the prognosis of early gastric cancer (EGC) is significantly better than that of advanced gastric cancer (AGC), the development of biomarkers to monitor the progression of chronic atrophic gastritis (CAG) to gastric cancer (GC) is essential. METHODS: Stomach tissue miRNA and mRNA sequences from patients with chronic non-atrophic gastritis (CNAG), CAG, precancerous lesions of gastric cancer (PLGC), and GC were analyzed. A publicly available GC-related miRNA microarray dataset was obtained from the Gene Expression Omnibus database. Spearman's correlation and differential gene analyses, and clinical validation were used to identify novel miRNAs correlating with CAG progression to GC. miRNA targets were predicted using weighted gene co-expression analysis and databases. A dual-luciferase reporter assay was performed to check for direct interaction between miR-196a-5p and ACER2. The CCK-8 and wound healing assays, and flow cytometry were performed to evaluate cell proliferation, migration, and apoptosis. RESULTS: miR-196a-5p was correlated with CAG progression to GC. Overexpression of miR-196a-5p promoted GC cell proliferation and migration and inhibited apoptosis, whereas suppression of miR-196a-5p exerted the opposite effect. Based on the prediction and luciferase assays, ACER2 was identified as the target of miR-196a-5p. ACER2 was downregulated in GC cell lines. Knockdown of ACER2 increased GC cell proliferation rates and migration ability and inhibited apoptosis, while ACER2 overexpression led to the opposite effect. CONCLUSIONS: miR-196a-5p correlated with CAG progression to GC and induced malignant biological behaviors of GC cells by targeting ACER2, providing a novel monitoring biomarker and target for GC prevention.

Alkaline ceramidase catalyzes the hydrolysis of ceramides via a catalytic mechanism shared by Zn2+-dependent amidases.

Human alkaline ceramidase 3 (ACER3) is one of three alkaline ceramidases (ACERs) that catalyze the conversion of ceramide to sphingosine. ACERs are members of the CREST superfamily of integral-membrane hydrolases. All CREST members conserve a set of three Histidine, one Aspartate, and one Serine residue. Although the structure of ACER3 was recently reported, catalytic roles for these residues have not been biochemically tested. Here, we use ACER3 as a prototype enzyme to gain insight into this unique class of enzymes. Recombinant ACER3 was expressed in yeast mutant cells that lack endogenous ceramidase activity, and microsomes were used for biochemical characterization. Six-point mutants of the conserved CREST motif were developed that form a Zn-binding active site based on a recent crystal structure of human ACER3. Five point mutants completely lost their activity, with the exception of S77A, which showed a 600-fold decrease compared with the wild-type enzyme. The activity of S77C mutant was pH sensitive, with neutral pH partially recovering ACER3 activity. This suggested a role for S77 in stabilizing the oxyanion of the transition state. Together, these data indicate that ACER3 is a Zn2+-dependent amidase that catalyzes hydrolysis of ceramides via a similar mechanism to other soluble Zn-based amidases. Consistent with this notion, ACER3 was specifically inhibited by trichostatin A, a strong zinc chelator.

Resveratrol Affects Sphingolipid Metabolism in A549 Lung Adenocarcinoma Cells.

Resveratrol is a naturally occurring polyphenol which has various beneficial effects, such as anti-inflammatory, anti-tumor, anti-aging, antioxidant, and neuroprotective effects, among others. The anti-cancer activity of resveratrol has been related to alterations in sphingolipid metabolism. We analyzed the effect of resveratrol on the enzymes responsible for accumulation of the two sphingolipids with highest functional activity-apoptosis promoting ceramide (CER) and proliferation-stimulating sphingosine-1-phosphate (S1P)-in human lung adenocarcinoma A549 cells. Resveratrol treatment induced an increase in CER and sphingosine (SPH) and a decrease in sphingomyelin (SM) and S1P. Our results showed that the most common mode of CER accumulation, through sphingomyelinase-induced hydrolysis of SM, was not responsible for a CER increase despite the reduction in SM in A549 plasma membranes. However, both the activity and the expression of CER synthase 6 were upregulated in resveratrol-treated cells, implying that CER was accumulated as a result of stimulated de novo synthesis. Furthermore, the enzyme responsible for CER hydrolysis, alkaline ceramidase, was not altered, suggesting that it was not related to changes in the CER level. The enzyme maintaining the balance between apoptosis and proliferation, sphingosine kinase 1 (SK1), was downregulated, and its expression was reduced, resulting in a decrease in S1P levels in resveratrol-treated lung adenocarcinoma cells. In addition, incubation of resveratrol-treated A549 cells with the SK1 inhibitors DMS and fingolimod additionally downregulated SK1 without affecting its expression. The present studies provide information concerning the biochemical processes underlying the influence of resveratrol on sphingolipid metabolism in A549 lung cancer cells and reveal possibilities for combined use of polyphenols with specific anti-proliferative agents that could serve as the basis for the development of complex therapeutic strategies.

Sphingolipid Catabolism and Glycerophospholipid Levels Are Altered in Erythrocytes and Plasma from Multiple Sclerosis Patients.

Multiple sclerosis (MS) is an autoimmune, inflammatory, degenerative disease of the central nervous system. Changes in lipid metabolism have been suggested to play important roles in MS pathophysiology and progression. In this work we analyzed the lipid composition and sphingolipid-catabolizing enzymes in erythrocytes and plasma from MS patients and healthy controls. We observed reduction of sphingomyelin (SM) and elevation of its products-ceramide (CER) and shingosine (SPH). These changes were supported by the detected up-regulation of the activity of acid sphingomyelinase (ASM) in MS plasma and alkaline ceramidase (ALCER) in erythrocytes from MS patients. In addition, Western blot analysis showed elevated expression of ASM, but not of ALCER. We also compared the ratios between saturated (SAT), unsaturated (UNSAT) and polyunsaturated fatty acids and suggest, based on the significant differences observed for this ratio, that the UNSAT/SAT values could serve as a marker distinguishing erythrocytes and plasma of MS from controls. In conclusion, the application of lipid analysis in the medical practice would contribute to definition of more precise diagnosis, analysis of disease progression, and evaluation of therapeutic strategies. Based on the molecular changes of blood lipids in neurodegenerative pathologies, including MS, clinical lipidomic analytical approaches could become a promising contemporary tool for personalized medicine.

Arabidopsis alkaline ceramidase ACER functions in defense against insect herbivory.

Plant sphingolipids are important membrane components and bioactive molecules in development and defense responses. However, the function of sphingolipids in plant defense, especially against herbivores, is not fully understood. Here, we report that Spodoptera exigua feeding affects sphingolipid metabolism in Arabidopsis, resulting in increased levels of sphingoid long-chain bases, ceramides, and hydroxyceramides. Insect-induced ceramide and hydroxyceramide accumulation is dependent on the jasmonate signaling pathway. Loss of the Arabidopsis alkaline ceramidase ACER increases ceramides and decreases long-chain base levels in plants; in this work, we found that loss of ACER enhances plant resistance to S. exigua and improves response to mechanical wounding. Moreover, acer-1 mutants exhibited more severe root-growth inhibition and higher anthocyanin accumulation than wild-type plants in response to methyl jasmonate treatment, indicating that loss of ACER increases sensitivity to jasmonate and that ACER functions in jasmonate-mediated root growth and secondary metabolism. Transcript levels of ACER were also negatively regulated by jasmonates, and this process involves the transcription factor MYC2. Thus, our findings reveal that ACER is involved in mediating jasmonate-related plant growth and defense and that jasmonates function in regulating the expression of ACER.

Circular RNA circ_0001955 promotes hepatocellular carcinoma tumorigenesis by up-regulating alkaline ceramidase 3 expression through microRNA-655-3p.

The involvement of certain circular RNAs (circRNAs) in the development of hepatocellular carcinoma (HCC) has been reported. Herein, this study aimed to investigate the function and mechanism of circ_0001955 in HCC tumorigenesis. Expression of circ_0001955, miR-655-3p, and alkaline ceramidase 3 (ACER3) was evaluated by quantitative real-time PCR and Western blot. Cell counting kit-8, colony formation, transwell, tube formation, flow cytometry and tumor xenograft assays were adopted to perform in vitro and in vivo experiments. The direct interaction between miR-655-3p and circ_0001955 or ACER3 was verified using dual-luciferase reporter and RNA immunoprecipitation assays. Circ_0001955 was highly expression in HCC tissues and cells. Functionally, circ_0001955 deletion suppressed HCC tumorigenesis in vitro by suppressing cell growth, metastasis and angiogenesis. Mechanistically, circ_0001955 could competitively sponge miR-655-3p, which targeted ACER3. Besides that, miR-655-3p silencing abolished the anticancer action of circ_0001955 silencing on HCC cells. Moreover, miR-655-3p overexpression inhibited HCC cell oncogenic phenotypes mentioned above, which were attenuated by ACER3 up-regulation. Additionally, circ_0001955 knockdown also impeded HCC growth in a mouse model. In all, this study suggested a novel circ_0001955/miR-655-3p/ACER3 pathway in HCC progression.

LINC01087 indicates a poor prognosis of glioma patients with preoperative MRI.

Long intergenic non-coding RNA 01,087 (LINC01087) has been concerned as an oncogene in breast cancer, while its mechanism in glioma has been little surveyed. Thus, we searched the prognostic value and functional action of LINC01087 in glioma. Glioma patients after preoperative MRI diagnosis were enrolled, and LINC01087, microRNA (miR)-1277-5p, and alkaline ceramidase 3 (ACER3) levels were tested in glioma cancer tissue. The correlation between LINC01087 expression and the survival of patients were analyzed. LINC01087, miR-1277-5p, and ACER3 levels in U251 cells were altered via transfection, and cell malignant phenotypes were monitored. The relationship between miR-1277-5p and LINC01087 or ACER3 was detected. The LINC01087 and ACER3 expression was in up-regulation and the miR-1277-5p expression was in down-regulation in clinical glioma samples. High expression of LINC01087 was associated with poor prognosis of glioma patients with preoperative MRI. LINC01087 silencing restrained tumor malignancy in glioma cells. Mechanistically, LINC01087 directly interacted with miR-1277-5p. ACER3 was a known target of miR-1277-5p. Moreover, rescue assays reveal that miR-1277-5p overexpression (or ACER3 overexpression) reversed the effects of LINC01087 upregulation (or miR-1277-5p upregulation) on glioma cells. LINC01087 has prognostic significance in glioma and silencing LINC01087 deters glioma development through elevating miR-1277-5p to reduce ACER3 expression.

ACER3-related leukoencephalopathy: expanding the clinical and imaging findings spectrum due to novel variants.

BACKGROUND: Leukodystrophies are the main subgroup of inherited CNS white matter disorders which cause significant mortality and morbidity in early years of life. Diagnosis is mostly based on clinical context and neuroimaging findings; however, genetic tools, particularly whole-exome sequencing (WES), have led to comprehending the causative gene and molecular events contributing to these disorders. Mutation in Alkaline Ceramidase 3 (ACER3) gene which encodes alkaline ceramidase enzyme that plays a crucial role in cellular growth and viability has been stated as an uncommon reason for inherited leukoencephalopathies. Merely only two ACER3 mutations in cases of progressive leukodystrophies have been reported thus far. RESULTS: In the current study, we have identified three novel variants in ACER3 gene in cases with new neurological manifestations including developmental regression, dystonia, and spasticity. The detected variants were segregated into family members. CONCLUSION: Our study expands the clinical, neuroimaging, electroencephalographic, and genetic spectrum of ACER3 mutations. Furthermore, we reviewed and compared the findings of all the previously reported cases and the cases identified here in order to facilitate their diagnosis and management.

Discovery of deoxyceramide analogs as highly selective ACER3 inhibitors in live cells.

Acid (AC), neutral (NC) and alkaline ceramidase 3 (ACER3) are the most ubiquitous ceramidases and their therapeutic interest as targets in cancer diseases has been well sustained. This supports the importance of discovering potent and specific inhibitors for further use in combination therapies. Although several ceramidase inhibitors have been reported, most of them target AC and a few focus on NC. In contrast, well characterized ACER3 inhibitors are lacking. Here we report on the synthesis and screening of two series of 1-deoxy(dihydro)ceramide analogs on the three enzymes. Activity was determined using fluorogenic substrates in recombinant human NC (rhNC) and both lysates and intact cells enriched in each enzyme. None of the molecules elicited a remarkable AC inhibitory activity in either experimental setup, while using rhNC, several compounds of both series were active as non-competitive inhibitors with Ki values between 1 and 5 µM. However, a dramatic loss of potency occurred in NC-enriched cell lysates and no activity was elicited in intact cells. Interestingly, several compounds of Series 2 inhibited ACER3 dose-dependently in both cell lysates and intact cells with IC50's around 20 µM. In agreement with their activity in live cells, they provoked a significant increase in the amounts of ceramides. Overall, this study identifies highly selective ACER3 activity blockers in intact cells, opening the door to further medicinal chemistry efforts aimed at developing more potent and specific compounds.

Transcriptional changes revealed genes and pathways involved in the deficient testis caused by the inhibition of alkaline ceramidase (Dacer) in Drosophila melanogaster.

Sphingolipids are ubiquitous structural components of eukaryotic cell membranes which are vital for maintaining the integrity of cells. Alkaline ceramidase is a key enzyme in sphingolipid biosynthesis pathway; however, little is known about the role of the enzyme in the male reproductive system of Drosophila melanogaster. To investigate the impact of alkaline ceramidase (Dacer) on male Drosophila, we got Dacer deficiency mutants (MUs) and found they displayed apparent defects in the testis's phenotype. To profile the molecular changes associated with this abnormal phenotype, we performed de novo transcriptome analyses of the MU and wildtype (WT) testes; and revealed 1239 upregulated genes and 1102 downregulated genes. Then, six upregulated DEGs (papilin [Ppn], croquemort [Crq], terribly reduced optic lobes [Trol], Laminin, Wunen-2, collagen type IV alpha 1 [Cg25C]) and three downregulated DEGs (mucin related 18B [Mur18B], rhomboid-7 [Rho-7], CG3168) were confirmed through quantitative real-time polymerase chain reaction in WT and MU samples. The differentially expressed genes were mainly associated with catalytic activity, oxidoreductase activity and transmembrane transporter activity, which significantly contributed to extracellular matrix-receptor interaction, fatty acids biosynthesis as well as glycine, serine, and threonine metabolism. The results highlight the importance of Dacer in the reproductive system of D. melanogaster and provide valuable resources to dig out the specific biological functions of Dacer in insect reproduction.

Alkaline ceramidase family: The first two decades.

Ceramidases are a group of enzymes that catalyze the hydrolysis of ceramide, dihydroceramide, and phytoceramide into sphingosine (SPH), dihydrosphingosine (DHS), and phytosphingosine (PHS), respectively, along with a free fatty acid. Ceramidases are classified into the acid, neutral, and alkaline ceramidase subtypes according to the pH optima for their catalytic activity. YPC1 and YDC1 were the first alkaline ceramidase genes to be identified and cloned from the yeast Saccharomyces cerevisiae two decades ago. Subsequently, alkaline ceramidase genes were identified from other species, including one Drosophila melanogaster ACER gene (Dacer), one Arabidopsis thaliana ACER gene (AtACER), three Mus musculus ACER genes (Acer1, Acer2, and Acer3), and three Homo sapiens ACER genes (ACER1, ACER2, and ACER3). The protein products of these genes constitute a large protein family, termed the alkaline ceramidase (ACER) family. All the biochemically characterized members of the ACER family are integral membrane proteins with seven transmembrane segments in the Golgi complex or endoplasmic reticulum, and they each have unique substrate specificity. An increasing number of studies suggest that the ACER family has diverse roles in regulating sphingolipid metabolism and biological processes. Here we discuss the discovery of the ACER family, the biochemical properties, structures, and catalytic mechanisms of its members, and its role in regulating sphingolipid metabolism and biological processes in yeast, insects, plants, and mammals.

TIMELESS regulates sphingolipid metabolism and tumor cell growth through Sp1/ACER2/S1P axis in ER-positive breast cancer.

Breast cancer is one of the most common female malignant cancers. Biorhythm disorder largely increases the risk of breast cancer. We aimed to investigate the biological functions and molecular mechanisms of circadian gene TIMELESS circadian regulator (TIM) in estrogen receptor (ER)-positive breast cancer and provide a new therapeutic target for breast cancer patients. Here, we explored that the expression of TIM was elevated in breast cancer, and high expression of TIM in cancer tissues was associated with poor prognosis, especially in the ER-positive breast cancer patients. In addition, we found that TIM promoted cell proliferation and enhanced mitochondrial respiration. TIM interacted with specificity protein 1 (Sp1) which contributes to upregulate the expression of alkaline ceramidase 2 (ACER2). Moreover, ACER2 is responsible for TIM-mediated promotive effects of cell growth and mitochondrial respiration. Collectively, our research unveiled a novel function of TIM in sphingolipid metabolism through interaction with Sp1. It provides a new theoretical explanation for the pathogenesis of breast cancer, and targeting TIM may serve as a potential therapeutic target for ER-positive breast cancer.

LncRNA KCNQ1OT1 inhibits the radiosensitivity and promotes the tumorigenesis of hepatocellular carcinoma via the miR-146a-5p/ACER3 axis.

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death, and radiotherapy is currently one of the main treatments. Long non-coding RNAs (lncRNAs) are associated with the radiosensitivity and tumorigenesis of HCC. However, the role and molecular mechanism of potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 (KCNQ1OT1) in HCC are still unclear. The relative expression of KCNQ1OT1, microRNA-146a-5p (miR-146a-5p) and alkaline ceramidase 3 (ACER3) was quantified by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Clonogenic assay was used to assess the radiosensitivity of cells. Cell apoptosis and metastasis were evaluated by flow cytometry and transwell assays, respectively. The protein levels of apoptosis markers, metastasis markers and ACER3 were detected by western blot (WB) analysis. The relationship between miR-146a-5p and KCNQ1OT1 or ACER3 was determined by dual-luciferase reporter assay. Additionally, animal experiments were carried out to explore the effect of KCNQ1OT1 silencing on HCC tumor growth in vivo. KCNQ1OT1 was highly expressed in HCC, and its knockdown hindered the proliferation and metastasis, while increased the radiosensitivity and apoptosis of HCC cells. MiR-146a-5p could interact with KCNQ1OT1, and its inhibition reversed the effects of silenced-KCNQ1OT1 on the radiosensitivity and tumorigenesis of HCC cells. Besides, ACER3 was a target of miR-146a-5p, and its overexpression inversed the effects of miR-146a-5p mimic on the radiosensitivity and tumorigenesis of HCC cells. The expression of ACER3 was regulated by KCNQ1OT1 and miR-146a-5p. Furthermore, KCNQ1OT1 also could reduce the growth of HCC by regulating the miR-146a-5p/ACER3 axis in vivo. Our study suggested that KCNQ1OT1 improved ACER3 expression to regulate the radiosensitivity and tumorigenesis of HCC through sponging miR-146a-5p, indicating that KCNQ1OT1 might be a new therapeutic target for HCC.

Maternal and fetal alkaline ceramidase 2 is required for placental vascular integrity in mice.

Sphingolipids have been implicated in mammalian placental development and function, but their regulation in the placenta remains unclear. Herein we report that alkaline ceramidase 2 (ACER2) plays a key role in sustaining the integrity of the placental vasculature by regulating the homeostasis of sphingolipids in mice. The mouse alkaline ceramidase 2 gene (Acer2) is highly expressed in the placenta between embryonic day (E) 9.5 and E12.5. Acer2 deficiency in both the mother and fetus decreases the placental levels of sphingolipids, including sphingoid bases (sphingosine and dihydrosphingosine) and sphingoid base-1-phosphates (sphingosine-1-phosphate and dihydrosphingosine-1-phosphate) and results in the in utero death of ≈50% of embryos at E12.5 whereas Acer2 deficiency in either the mother or fetus has no such effects. Acer2 deficiency causes hemorrhages from the maternal vasculature in the junctional and/or labyrinthine zones in E12.5 placentas. Moreover, hemorrhagic but not non-hemorrhagic Acer2-deficient placentas exhibit an expansion of parietal trophoblast giant cells with a concomitant decrease in the area of the fetal blood vessel network in the labyrinthine zone, suggesting that Acer2 deficiency results in embryonic lethality due to the atrophy of the fetal blood vessel network in the placenta. Taken together, these results suggest that ACER2 sustains the integrity of the placental vasculature by controlling the homeostasis of sphingolipids in mice.

Novel genes involved in the genetic architecture of temperament in Brahman cattle.

Cattle temperament is a complex and economically relevant trait. The objective of this study was to identify genomic regions and genes associated with cattle temperament. From a Brahman cattle population of 1,370 animals evaluated for temperament traits (Exit velocity-EV, Pen Score-PS, Temperament Score-TS), two groups of temperament-contrasting animals were identified based on their EV-average values ±1/2 standard deviation (SD). To be considered in the calm group, the EV of females ranged between 0.16-1.82 m/s (n = 50) and the EV of males ranged between 0.4-1.56 m/s (n = 48). Females were classified as temperamental if their EV ranged between 3.13-7.66 m/s (n = 46) and males were classified as temperamental if their EV ranged between 3.05-10.83 m/s (n = 45). Selected animals were genotyped using a total of 139,376 SNPs (GGP-HD-150K), evaluated for their association with EV. The Genome-Wide Association analysis (GWAS) identified fourteen SNPs: rs135340276, rs134895560, rs110190635, rs42949831, rs135982573, rs109393235, rs109531929, rs135087545, rs41839733, rs42486577, rs136661522, rs110882543, rs110864071, rs109722627, (P<8.1E-05), nine of them were located on intergenic regions, harboring seventeen genes, of which only ACER3, VRK2, FANCL and SLCO3A1 were considered candidate associated with bovine temperament due to their reported biological functions. Five SNPs were located at introns of the NRXN3, EXOC4, CACNG4 and SLC9A4 genes. The indicated candidate genes are implicated in a wide range of behavioural phenotypes and complex cognitive functions. The association of the fourteen SNPs on bovine temperament traits (EV, PS and TS) was evaluated; all these SNPs were significant for EV; only some were associated with PS and TS. Fourteen SNPs were associated with EV which allowed the identification of twenty-one candidate genes for Brahman temperament. From a functional point of view, the five intronic SNPs identified in this study, are candidates to address control of bovine temperament, further investigation will probe their role in expression of this trait.

Human alkaline ceramidase 2 promotes the growth, invasion, and migration of hepatocellular carcinoma cells via sphingomyelin phosphodiesterase acid-like 3B.

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. It has a poor prognosis because it is often diagnosed at the advanced stage when treatments are limited. In addition, HCC pathogenesis is not fully understood, and this has affected early diagnosis and treatment of this disease. Human alkaline ceramidase 2 (ACER2), a key enzyme that regulates hydrolysis of cellular ceramides, affects cancer cell survival, however its role in HCC has not been well characterized. Our results showed that ACER2 is overexpressed in HCC tissues and cell lines. In addition, high ACER2 protein expression was associated with tumor growth; ACER2 knockdown resulted in decreased cell growth and migration. Sphingomyelin phosphodiesterase acid-like 3B (SMPDL3B) promoted HCC cell growth, invasion, and migration; SMPDL3B knockdown had a significant inhibitory effect on HCC tumor growth in vivo. Moreover, ACER2 positively regulated the protein level of SMPDL3B. Of note, ACER2/SMPDL3B promoted ceramide hydrolysis and S1P production. This axis induced HCC survival and could be blocked by inhibition of S1P formation. In conclusion, ACER2 promoted HCC cell survival and migration, possibly via SMPDL3B. Thus, inhibition of ACER2/SMPDL3B may be a novel therapeutic target for HCC treatment.