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β-Galactosylceramidase (GALC) is a lysosomal enzyme involved in sphingolipid metabolism by removing β-galactosyl moieties from β-galactosylceramide and β-galactosylsphingosine. Previous observations have shown that GALC may exert pro-oncogenic functions in melanoma and Galc silencing, leading to decreased oncogenic activity in murine B16 melanoma cells. The tumor-driving BRAF(V600E) mutation is present in approximately 50% of human melanomas and represents a major therapeutic target. However, such mutation is missing in melanoma B16 cells. Thus, to assess the impact of GALC in human melanoma in a more relevant BRAF-mutated background, we investigated the effect of GALC overexpression on the proteomic landscape of A2058 and A375 human melanoma cells harboring the BRAF(V600E) mutation. The results obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) demonstrate that significant differences exist in the protein landscape expressed under identical cell culture conditions by A2058 and A375 human melanoma cells, both harboring the same BRAF(V600E)-activating mutation. GALC overexpression resulted in a stronger impact on the proteomic profile of A375 cells when compared to A2058 cells (261 upregulated and 184 downregulated proteins versus 36 and 14 proteins for the two cell types, respectively). Among them, 25 proteins appeared to be upregulated in both A2058-upGALC and A375-upGALC cells, whereas two proteins were significantly downregulated in both GALC-overexpressing cell types. These proteins appear to be involved in melanoma biology, tumor invasion and metastatic dissemination, tumor immune escape, mitochondrial antioxidant activity, endoplasmic reticulum stress responses, autophagy, and/or apoptosis. Notably, analysis of the expression of the corresponding genes in human skin cutaneous melanoma samples (TCGA, Firehose Legacy) using the cBioPortal for Cancer Genomics platform demonstrated a positive correlation between GALC expression and the expression levels of 14 out of the 27 genes investigated, thus supporting the proteomic findings. Overall, these data indicate for the first time that the expression of the lysosomal sphingolipid-metabolizing enzyme GALC may exert a pro-oncogenic impact on the proteomic landscape in BRAF-mutated human melanoma.

Sphingolipidoses are inborn errors of metabolism due to the pathogenic mutation of genes that encode for lysosomal enzymes, transporters, or enzyme cofactors that participate in the sphingolipid catabolism. They represent a subgroup of lysosomal storage diseases characterized by the gradual lysosomal accumulation of the substrate(s) of the defective proteins. The clinical presentation of patients affected by sphingolipid storage disorders ranges from a mild progression for some juvenile- or adult-onset forms to severe/fatal infantile forms. Despite significant therapeutic achievements, novel strategies are required at basic, clinical, and translational levels to improve patient outcomes. On these bases, the development of in vivo models is crucial for a better understanding of the pathogenesis of sphingolipidoses and for the development of efficacious therapeutic strategies. The teleost zebrafish (Danio rerio) has emerged as a useful platform to model several human genetic diseases owing to the high grade of genome conservation between human and zebrafish, combined with precise genome editing and the ease of manipulation. In addition, lipidomic studies have allowed the identification in zebrafish of all of the main classes of lipids present in mammals, supporting the possibility to model diseases of the lipidic metabolism in this animal species with the advantage of using mammalian lipid databases for data processing. This review highlights the use of zebrafish as an innovative model system to gain novel insights into the pathogenesis of sphingolipidoses, with possible implications for the identification of more efficacious therapeutic approaches.

Arrhythmias are a critical health burden, responsible for a significant proportion of sudden cardiac death. They arise from inherited or acquired abnormalities in cardiac ion channels or their associated regulatory proteins functioning within cardiomyocytes. In opposite with the classical in vitro models, human induced pluripotent stem cells–derived cardiomyocytes (hiPSC-CMs) offer a patient-specific model that recapitulates disease phenotype and mirrors the reaction to pharmacotherapy. Thus far, the hiPSC-CMs model has genuinely improved our knowledge concerning both, the pathogenicity of genetic variants in inherited arrhythmias and the toxicity of some factors implicated in acquired forms of arrhythmia. Besides, as these cells preserve patient genetic background, they enable the customization of therapies and open thereby the door for personalized medicine. In this chapter, we will outline studies that leveraged the hiPSC-CMs model to explore the mechanism underlying inherited or acquired arrhythmic phenotypes and will point out its sustained limits.

β-galactosylceramidase (GALC) is a lysosomal enzyme that removes β-galactose from β-galactosylceramide, leading to the formation of the oncosuppressor metabolite ceramide. Recent observations have shown that GALC may exert opposite effects on tumor growth by acting as an oncosuppressive or oncogenic enzyme depending on the different experimental approaches, in vitro versus in vivo observations, preclinical versus clinical findings, and tumor type investigated. This review will recapitulate and discuss the contrasting experimental evidence related to the impact of GALC on the biological behavior of cancer and stromal cells and its contribution to tumor progression.

Background: Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) disease (COVID-19) mainly affects the respiratory system, but cardiac complications occur very often. SARS-CoV-2 entry in host cells is mediated by the interaction between the viral Spike (S) glycoprotein and the host angiotensin-converting enzyme 2 (ACE2). The use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor blockers (ARBs) might influence the expression of ACE2 and viral infection, but not much is known about these interactions. Aim: To evaluate the effects of ACEIs and ARBs during active viraemia. Methods: We tested the ACEI Lisinopril (at 100nM and 500nM) and the ARB Valsartan (at 10uM and 50uM) for one week on two cell types: cardiomyocytes derived from hiPSC (hiPSC-CMs) as heart model and a lung epithelial cancer cell line (16HBE) as pulmonary model. The SARS-CoV-2 wild strain was inoculated in the two treated cell types for one hour. Cell viability was measured 72 hours after infection. Supernatants were collected and titrated to verify the presence of infectious virus using a micro-neutralization assay on VERO-E6 cells. Levels of ACE2 mRNA and protein content on cell lysates were quantified after each treatment by RT-qPCR and western blot, respectively. Results: ACEI and ARB at both concentrations affected the viability of neither hiPSC-CMs nor 16HBE cells in the absence of virus. Vice versa, viral infection significantly decreased viability of both hiPSC-CMs (-46%; p Conclusion: These data suggest that ACEIs and ARBs do not worsen the SARS-CoV-2 infection. On the contrary, Valsartan seems to be protective against SARS-CoV-2 infection, possibly by reducing ACE2 expression.

We generated human induced pluripotent stem cells (hiPSCs) from dermal fibroblasts of a 40 years old female patient homozygous for the mutation c.535 G > A p.G179S on the KCNQ1 gene, causing a severe form of autosomal recessive Long QT Syndrome type 1 (AR-LQT1). The hiPSCs, generated using classical approach of the four retroviruses enconding the reprogramming factors OCT4, SOX2, cMYC and KLF4, display pluripotent stem cell characteristics, and differentiate into cell lineages of all three germ layers: endoderm, mesoderm and ectoderm. Keywords: Endoderm, Mesoderm, Ectoderm