Lysosomal diacylglycerol pyrophosphate phosphatase is not essential in Trypanosoma brucei.

Mg2+-independent phosphatidic acid phosphatase (PAP2), diacylglycerol pyrophosphate phosphatase 1 (Dpp1) is a membrane-associated enzyme in Saccharomyces cerevisiae. The enzyme is responsible for inducing the breakdown of ß-phosphate from diacylglycerol pyrophosphate (DGPP) into phosphatidate (PA) and then removes the phosphate from PA to give diacylglycerol (DAG). In this study through RNAi suppression, we have demonstrated that Trypanosoma brucei diacylglycerol pyrophosphate phosphatase 1 (TbDpp1) procyclic form production is not required for parasite survival in culture. The steady-state levels of triacylglycerol (TAG), the number of lipid droplets, and the PA content are all maintained constant through the inducible down-regulation of TbDpp1. Furthermore, the localization of C-terminally tagged variants of TbDpp1 in the lysosome was demonstrated by immunofluorescence microscopy.

Stem cell-derived organoid models for SARS-CoV-2 and its molecular interaction with host cells.

Modeling severe acute respiratory syndrome, Coronavirus 2 (SARS-CoV-2) infection in stem cell-derived organoids has helped in our understanding of the molecular pathogenesis of COVID-19 disease due to their resemblance to actual human tissues or organs. Over the past decade, organoid 3-dimensional (3D) cultures have represented a new perspective and considerable advancement over traditional in vitro 2-dimensional (2D) cell cultures. COVID-19 disease causes lung injury and multi-organ failure leading to death, especially in older patients. There is an urgent need for physiological models to study SARS-CoV-2 infection during the pandemic. Human stem cell-derived organoids can provide insight into understanding the SARS-CoV-2 cell entry molecular mechanism. Identifying such complexities will help to develop the best preventive drug targets.

Mitochondrial sphingosine-1-phosphate lyase is essential for phosphatidylethanolamine synthesis and survival of Trypanosoma brucei.

Sphingosine-1-phosphate is a signaling molecule involved in the control of cell migration, differentiation, survival and other physiological processes. This sphingolipid metabolite can be degraded by the action of sphingosine-1-phosphate lyase (SPL) to form hexadecenal and ethanolamine phosphate. The importance of SPL-mediated ethanolamine phosphate formation has been characterized in only few cell types. We show that in the protozoan parasite Trypanosoma brucei, expression of TbSpl is essential for cell survival. Ablation of TbSpl expression increased sphingosine-1-phosphate levels and reduced de novo formation and steady-state levels of the glycerophospholipid phosphatidylethanolamine (PE). Growth of TbSpl-depleted parasites could be in part rescued by ethanolamine supplementation to the growth medium, indicating that the main function of TbSpl is to provide ethanolamine phosphate for PE synthesis. In contrast to most cell types analyzed, where SPL localizes to the endoplasmic reticulum, we found by high-resolution microscopy that TbSpl is a mitochondrial protein. In spite of its mitochondrial localization, TbSpl depletion had no apparent effect on mitochondrial morphology but resulted in aggregation of acidocalcisomes. Our results link mitochondria to sphingolipid metabolism and suggest possible roles for PE in acidocalcisome function.

TbLpn, a key enzyme in lipid droplet formation and phospholipid metabolism, is essential for mitochondrial integrity and growth of Trypanosoma brucei.

Mammalian phosphatidic acid phosphatases, also called lipins, show high amino acid sequence identity to Saccharomyces cerevisiae Pah1p and catalyze the dephosphorylation of phosphatidic acid (PA) to diacylglycerol. Both the substrate and product of the reaction are key precursors for the synthesis of phospholipids and triacylglycerol (TAG). We now show that expression of the Trypanosoma brucei lipin homolog TbLpn is essential for parasite survival in culture. Inducible down-regulation of TbLpn in T. brucei procyclic forms increased cellular PA content, decreased the numbers of lipid droplets, reduced TAG steady-state levels and inhibited in vivo [3 H]TAG formation after labeling trypanosomes with [3 H]glycerol. In addition, fluorescence and transmission electron microscopy revealed that depletion of TbLpn caused major alterations in mitochondrial morphology and function, i.e., the appearance of distorted mitochondrial matrix, and reduced ATP production via oxidative phosphorylation. Effects of lipin depletion on mitochondrial integrity have previously not been reported. N- and C-terminally tagged forms of TbLpn were localized in the cytosol.

Recombinant fibromodulin and decorin effects on NF-κB and TGFß1 in the 4T1 breast cancer cell line.

Constitutive activation of nuclear factor-κB (NF-κB) stimulates cell proliferation and metastasis, and inhibits apoptosis in breast cancer. Transforming growth factor-ß (TGF-ß) signaling pathway is deregulated in breast cancer progression and metastasis. The aim of the present study was to investigate the inhibitory effects of the two small leucine rich proteoglycans fibromodulin (Fmod) and decorin (Dcn), overexpressed using adenovirus gene transfer, on NF-κB-activity and TGF-ß1-expression in the highly metastatic 4T1 breast cancer cell line. The results demonstrate that Fmod and Dcn overexpression is associated with NF-κB and TGF-ß1 downregulation, and that Fmod promotes this effect more effectively compared with Dcn.

The First Report of a 290-bp Deletion in ß-Globin Gene in the South of Iran.

BACKGROUND: ß-thalassemia is one of the most widespread disease in the world, including Iran. In this study, we reported, for the first time, a 290-bp ß-globin gene deletion in the south of Iran. METHODS: Four individuals from three unrelated families with Arabic ethnic background were studied in Khuzestan Province. Red blood cell indices and hemoglobin analysis were carried out according to the standard methods. Genomic DNA was obtained from peripheral blood cells by salting out procedures. ß-globin gene amplification, multiplex ligation-dependent probe amplification (MLPA) and DNA sequencing were performed. RESULTS: The PCR followed by sequencing and MLPA test of the ß-globin gene confirmed the presence of a 290-bp deletion in the heterozygous form, along with -88C>A mutation. All the individuals had elevated hemoglobin A2 and normal fetal hemoglobin levels. CONCLUSIONS: This mutation causes ß0-thalassemia and can be highly useful for prenatal diagnosis in compound heterozygous condition with different ß-globin gene mutations.