PLD1 Research Articles

Phospholipase D2 downregulates interleukin-1β secretion from tumor-associated macrophages to suppress bladder cancer progression.

The tumor microenvironment (TME) modulates therapeutic response and prognosis in patients with bladder cancer (BC). The roles of two phospholipase D (PLD) isoforms, PLD1 and PLD2 (hydrolysis of phosphatidylcholine to phosphatidic acid), in cancer cells have been well-studied in numerous cancer types, but their roles in the TME remain unclear. We used a mouse BC Pld2-KO carcinogenesis model and global transcriptomic analysis to reveal that PLD2 was significantly involved in BC progression through immunosuppressive pathways in the TME. We therefore focused on PLD2 and tumor-associated macrophages (TAMs), which were increased in Pld2-KO mice and further associated with poor prognoses in BC patients. Invitro, we found that Pld2-KO mouse TAMs had significantly enhanced proliferation, correlating closely with increased interleukin-1β (IL-1β) production. These results indicate that PLD2 suppresses BC progression by regulation of IL-1β secretion from TAMs in the TME, suggesting that PLD2 could serve as a potential therapeutic target for modifying the TME in BC.

Inhibition of phospholipase D1 reduces pancreatic carcinogenesis in mice partly through a FAK-dependent mechanism.

Phospholipase D (PLD) plays a critical role in cancer progression. However, its role in pancreatic cancer remains unclear. Thus, we evaluated the role of PLD1, one of two classical isoforms of PLD, in pancreatic carcinogenesis in vivo. The role of PLD1 in tumor growth was evaluated by subcutaneously transplanting human MIA PaCa-2 cells expressing endogenous PLD1 levels (Ctr KD cells) or cells in which PLD1 was knocked down (Pld1 KD cells) into immunodeficient mice. Twenty days post-implantation, tumors that arose from Pld1-KD cells were significantly smaller, compared to controls (Ctr KD). Then, we assessed the role of PLD1 in the tumor microenvironment, by subcutaneously implanting mouse LSL-KrasG12D/+;Trp53R172H/+;Pdx-1-Cre (KPC) cells into wild-type (WT) or PLD1 knockout (Pld1-/-) mice. Compared to WT, tumor growth was attenuated in Pld1-/- mice by 39%, whereas treatment of Pld1-/- mice with gemcitabine reduced tumor growth by 79%. When PLD1 was ablated in LSL-KrasG12D;Ptf1Cre/+ (KC) mice, no reduction in acinar cell loss was observed, compared to KC mice. Finally, treatment of KC mice with a small molecule inhibitor of PLD1 and PLD2 (FIPI) significantly reduced acinar cell loss and cell proliferation, compared to vehicle-treated mice. Mechanistically, the effect of PLD on tumor growth is mediated, partly, by the FAK pathway. In conclusion, while PLD1 is a critical regulator of pancreatic xenograft and allograft growth, playing an important role at the tumor and at the microenvironment levels, inhibition of PLD1 and PLD2 are necessary to reduce pancreatic carcinogenesis in KC mice, and might represent a novel therapeutic target.

Prenatal detection of novel compound heterozygous variants of the PLD1 gene in a fetus with congenital heart disease

Prenatal detection of novel compound heterozygous variants of the PLD1 gene in a fetus with congenital heart disease

Phospholipase D2 drives cellular lipotoxicity and tissue inflammation in alcohol-associated liver disease

AimsExcessive alcohol consumption leads to alcoholic liver disease (ALD), a major contributing factor to cirrhosis and hepatocellular carcinoma. In the present study we investigated the involvement of phospholipase D2 (PLD2) in the pathogenesis of ALD. Methods and materialsALD was induced in mice by chronic and binge ethanol feeding (the NIAAA model). Cellular transcriptome was examined by RNA-seq. Key findingsAnalysis of RNA-seq datasets indicated that PLD2 expression was up-regulated in liver tissues and in hepatocytes during ALD pathogenesis. Exposure of hepatocytes to ethanol treatment led to an increase in PLD2 expression. Similarly, ethanol feeding in mice stimulated PLD2 expression in the liver. On the contrary, PLD2 knockdown in hepatocytes down-regulated expression of pro-inflammatory and pro-lipogenic genes and dampened lipid accumulation. Consistently, PLD2 knockdown in mice significantly ameliorated ALD pathogenesis as evidenced by reduced steatosis and hepatic inflamamation. RNA-seq identified several metabolic pathways that were influenced by PLD2 deficiency. SignificanceOur data demonstrate that PLD2 is a novel regulator of ALD and suggest that small-molecule PLD2 inhibitors can be considered as a reasonable strategy for ALD treatment.

Effects of phospholipase D1-inhibitory peptide on the growth and metastasis of gastric cancer cells

Phospholipase D1 (PLD1) contributes to cancer development and progression through its effects on cell proliferation, survival, invasion, metastasis, angiogenesis, drug resistance, and modulation of the tumor microenvironment. Its central role in these processes makes it a promising target for novel cancer treatments aimed at inhibiting its activity and disrupting the signaling pathways it regulates. In this study, we aimed to investigate the effect of PLD1 inhibition on gastric cancer cell growth using a novel peptide inhibitor, TAT-TVTSP. PLD1, which plays a role in cancer progression, catalyzes the conversion of phosphatidylcholine into choline and phosphatidic acid through hydrolysis. To effectively target PLD1 in cells, we engineered TAT-TVTSP by fusing a PLD1-inhibitory peptide (TVTSP) with a cell-penetrating peptide (TAT). We observed that TAT-TVTSP effectively inhibited PLD1 activity in AGS gastric cancer cells. Moreover, TAT-TVTSP significantly inhibited the mammalian target of the rapamycin signaling pathway, including the phosphorylation of key downstream targets such as S6K1, AKT, S473, glycogen synthase kinase-3b, and forkhead box O1. TAT-TVTSP did not induce cell death, but it triggered cell cycle arrest by activating p21 and p27 via AKT phosphorylation. Functional assays revealed that TAT-TVTSP significantly impaired the colony-forming ability of AGS cells, thus inhibiting cell proliferation. Transwell and wound-healing assays revealed that this peptide disrupted the cellular behaviors critical to cancer progression, such as migration and invasion. In vivo, TAT-TVTSP significantly reduced tumor growth in the xenograft model of gastric cancer without any toxicity. Overall, our results suggest that TAT-TVTSP is a novel therapeutic agent for PLD1-mediated cancers.

RNA binding protein RALY facilitates colorectal cancer metastasis via enhancing exosome biogenesis in m6A dependent manner

Tumor metastasis is the leading cause of cancer-related death in patients with colorectal cancer (CRC). Heterogeneous nuclear ribonucleoproteins (hnRNPs) are RNA-binding proteins, involved in the tumorigenesis and metastasis of various cancers. However, the molecular mechanisms of hnRNPs in CRC metastasis remain unclear. This study aims to uncover the pivotal roles and molecular mechanisms of hnRNPs in CRC metastasis. Clinical database analysis suggested that the expression of hnRNP-Associated with Lethal Yellow (RALY, an important member of hnRNPs) was strongly correlated with the aggressiveness and survival of CRC patients. Gain- and loss-of-function studies demonstrated that RALY promotes the production of exosomes by increasing the formation of multivesicular bodies (MVBs) and enhancing the fusion of MVBs with the plasma membrane. Notably, RALY directly interacts with phospholipase D2 (PLD2) to enable exosome biogenesis, and cooperates with RBM15b to control PLD2 mRNA stability in an m6A-dependent manner. RALY-mediated exosome secretion activates pro-tumor macrophages and further facilitates CRC metastasis, while rescue experiments in vivo further confirmed that RALY-mediated exosome biogenesis facilitates CRC metastasis. Collectively, our findings demonstrate that RALY promotes exosome biogenesis and facilitates colorectal cancer metastasis by upregulating PLD2 and enhancing exosome production in an m6A-dependent manner, suggesting potential therapeutic strategies for combating CRC metastasis.

Molecular interactions between a diphenyl scaffold and PED/PEA15: Implications for type II diabetes therapeutics targeting PED/PEA15 – Phospholipase D1 interaction

In a recent study, we have identified BPH03 as a promising scaffold for the development of compounds aimed at modulating the interaction between PED/PEA15 (Phosphoprotein Enriched in Diabetes/Phosphoprotein Enriched in Astrocytes 15) and PLD1 (phospholipase D1), with potential applications in type II diabetes therapy. PED/PEA15 is known to be overexpressed in certain forms of diabetes, where it binds to PLD1, thereby reducing insulin-stimulated glucose transport. The inhibition of this interaction reestablishes basal glucose transport, indicating PED as a potential target of ligands capable to recover glucose tolerance and insulin sensitivity. In this study, we employ computational methods to provide a detailed description of BPH03 interaction with PED, evidencing the presence of a hidden druggable pocket within its PLD1 binding surface. We also elucidate the conformational changes that occur during PED interaction with BPH03. Moreover, we report new NMR data supporting the in-silico findings and indicating that BPH03 disrupts the PED/PLD1 interface displacing PLD1 from its interaction with PED. Our study represents a significant advancement toward the development of potential therapeutics for the treatment of type II diabetes.

Mapping the global interactome of the ARF family reveals spatial organization in cellular signaling pathways.

The ADP-ribosylation factors (ARFs) and ARF-like (ARL) GTPases serve as essential molecular switches governing a wide array of cellular processes. In this study, we used proximity-dependent biotin identification (BioID) to comprehensively map the interactome of 28 out of 29 ARF and ARL proteins in two cellular models. Through this approach, we identified ∼3000 high-confidence proximal interactors, enabling us to assign subcellular localizations to the family members. Notably, we uncovered previously undefined localizations for ARL4D and ARL10. Clustering analyses further exposed the distinctiveness of the interactors identified with these two GTPases. We also reveal that the expression of the understudied member ARL14 is confined to the stomach and intestines. We identified phospholipase D1 (PLD1) and the ESCPE-1 complex, more precisely, SNX1, as proximity interactors. Functional assays demonstrated that ARL14 can activate PLD1 in cellulo and is involved in cargo trafficking via the ESCPE-1 complex. Overall, the BioID data generated in this study provide a valuable resource for dissecting the complexities of ARF and ARL spatial organization and signaling.

Abstract 3058: Cofilin 1 Mediates Fatty Acid-induced Foam Cell Formation And Inflammation In Mouse Bone Marrow-derived Macrophages

Background: Macrophages contribute to the development of atherosclerosis, in part through the accumulation of lipid droplets and subsequent transformation into highly inflammatory, lipid laden foam cells. Our previous work suggested that the RAGE/DIAPH1 axis plays a key role in regulating lipid metabolism, as deletion of Diaph1 in hepatocytes reduced nuclear translocation of SREBP1 through the actin cytoskeleton. Cofilin 1 (CFL1) is an actin polymerization molecule which has also been linked to the nuclear translocation of SRBP1, as well as triglyceride synthesis through activation of phospholipase D1. In the aforementioned study by our group, Diaph1 deletion was found to increase the Serine 3 phosphorylation (i.e., inactivation) of Cfl1 . Hypothesis: Accordingly, we hypothesized that CFL1 plays a role in lipid droplet accumulation in macrophages, potentially increasing the risk of atherosclerotic development. Methods: To investigate its role in macrophage lipid handling, we silenced Cfl1 in bone marrow derived macrophages (BMDMs) extracted from male C57BL/6J mice, using silencing RNAs and scramble controls. BMDMs were treated with a mixture of fatty acids palmitate and oleate (250 uM). The effects of Cfl1 knockdown on lipid accumulation were assessed using immunohistochemical staining (Bodipy). Quantitative (q)PCR was used to interrogate the mechanisms underlying these effects, and their impact on inflammation. Results: Cfl1- silenced (75% knockdown shown by qPCR) vs. scramble cells exhibited a significant decrease in the ratio of Bodipy to DAPI % area (p=0.0001). By qPCR, compared to scramble controls, BMDMs subjected to silencing of Cfl1 and incubated with fatty acids (palmitate-oleate) displayed significantly lower mRNA expression of Cd36 (p=0.0018) ; Ppargc1a (p=0.004) , Il6 (p<0.0001), and Tnfa (p=0.013). Conclusions: Our results indicate that silencing of Cfl1 leads to a decrease in lipid accumulation and markers of inflammation in BMDMs. Collectively, our data suggest that the effects of Cfl1 silencing on lipid handling result from decreased fatty acid uptake, which limits fatty acid oxidation on account of fatty acid availability in the cell. Studies are underway to probe the implications of these findings in atherosclerosis.

PLD2 deficiency alleviates endothelial glycocalyx degradation in LPS-induced ARDS/ALI

- Acute respiratory distress syndrome (ARDS)/acute lung injury (ALI) is a life-threatening condition marked by severe lung inflammation and increased lung endothelial barrier permeability. Endothelial glycocalyx deterioration is the primary factor of vascular permeability changes in ARDS/ALI. Although previous studies have shown that phospholipase D2 (PLD2) is closely related to the onset and progression of ARDS/ALI, its role and mechanism in the damage of endothelial cell glycocalyx remains unclear. We used LPS-induced ARDS/ALI mice (in vivo) and LPS-stimulated injury models of EA.hy926 endothelial cells (in vitro). We employed C57BL/6 mice, including wild-type and PLD2 knockout (PLD2−/−) mice, to establish the ARDS/ALI model. We applied immunofluorescence and ELISA to examine changes in syndecan-1 (SDC-1), matrix metalloproteinase-9 (MMP9), inflammatory cytokines (TNF-α, IL-6, and IL-1β) levels and the effect of external factors, such as phosphatidic acid (PA), 1-butanol (a PLD inhibitor), on SDC-1 and MMP9 expression levels. We found that PLD2 deficiency inhibits SDC-1 degradation and MMP9 expression in LPS-induced ARDS/ALI. Externally added PA decreases SDC-1 levels and increases MMP9 in endothelial cells, hence underlining PA's role in SDC-1 degradation. Additionally, PLD2 deficiency decreases the production of inflammatory cytokines (TNF-α, IL-6, and IL-1β) in LPS-induced ARDS/ALI. In summary, these findings suggest that PLD2 deficiency plays a role in inhibiting the inflammatory process and protecting against endothelial glycocalyx injury in LPS-induced ARDS/ALI.

PLD2 deletion ameliorates sepsis-induced cardiomyopathy by suppressing cardiomyocyte pyroptosis via the NLRP3/caspase 1/GSDMD pathway

ObjectiveSepsis-induced cardiomyopathy (SICM) is a life-threatening complication. Phospholipase D2 (PLD2) is crucial in mediating inflammatory reactions and is associated with the prognosis of patients with sepsis. Whether PLD2 is involved in the pathophysiology of SICM remains unknown. This study aimed to investigate the effect of PLD2 knockout on SICM and to explore potential mechanisms.MethodsThe SICM model was established using cecal ligation and puncture in wild-type and PLD2-knockout mice and lipopolysaccharide (LPS)-induced H9C2 cardiomyocytes. Transfection with PLD2-shRNA lentivirus and a PLD2 overexpression plasmid were used to interfere with PLD2 expression in H9C2 cells. Cardiac pathological alterations, cardiac function, markers of myocardial injury, and inflammatory factors were used to evaluate the SICM model. The expression of pyroptosis-related proteins (NLRP3, cleaved caspase 1, and GSDMD-N) was assessed using western blotting, immunofluorescence, and immunohistochemistry.ResultsSICM mice had myocardial tissue damage, increased inflammatory response, and impaired heart function, accompanied by elevated PLD2 expression. PLD2 deletion improved cardiac histological changes, mitigated cTNI production, and enhanced the survival of the SICM mice. Compared with controls, PLD2-knockdown H9C2 exhibits a decrease in inflammatory markers and lactate dehydrogenase production, and scanning electron microscopy results suggest that pyroptosis may be involved. The overexpression of PLD2 increased the expression of NLRP3 in cardiomyocytes. In addition, PLD2 deletion decreased the expression of pyroptosis-related proteins in SICM mice and LPS-induced H9C2 cells.ConclusionPLD2 deletion is involved in SICM pathogenesis and is associated with the inhibition of the myocardial inflammatory response and pyroptosis through the NLRP3/caspase 1/GSDMD pathway.

Phosphatidic Acid Promoting the Generation of Interleukin-17A Producing Double-Negative T Cells by Enhancing mTORC1 Signaling in Lupus.

The goal was to investigate the role and intracellular regulatory mechanisms of double-negative T (DNT) cells in the pathogenesis of systemic lupus erythematosus (SLE). DNT cells were assessed in murine models, patients with SLE, and controls using flow cytometry (FCM). DNT cells from either resiquimod (R848) or vehicle-treated C57BL/6 (B6) mice were cultured with B cells from R848-treated mice to explore functions. Differential mechanistic target of rapamycin (mTOR) pathway signaling in DNT cells measured using FCM and quantitative polymerase chain reaction was validated by rapamycin inhibition. Candidate lipid metabolites detected using liquid chromatography with electrospray ionization mass spectrometry/mass spectrometry were functionally assessed in DNT cell cultures. DNT cells were markedly increased in both spontaneous and induced mouse lupus models and in patients with SLE. Expanded DNT cells from R848-treated B6 mice produced elevated interleukin (IL)-17A and IgG with increased germinal center B (GCB) cells. Expansion of DNT cells associated with activation of mTORC1 pathway that both IL-17A levels and the number of DNT cells exhibited dose-dependent reduction with rapamycin treatment. Lipidomics studies revealed differential patterns of lipid metabolites in T cells of R848-treated mice. Among candidate metabolites, elevated phosphatidic acid (PA) that was partially controlled by phospholipase D2 increased the expression of the mTORC1 downstream target p-S6 and positively expanded IL-17A-producing DNT cells. Similarly, elevated proportions of circulating DNT cells in patients with SLE correlated with disease activity and proteinuria, and IL-17A secretion was elevated after in vitro PA stimulation. The accumulation of PA in T cells could activate the mTORC1 pathway, promoting DNT cell expansion and IL-17A secretion, resulting in GCB cell abnormalities in lupus.

Abstract 3356: Inhibiting phospholipase D1 reduces pancreatic carcinogenesis in mice

Abstract New therapeutic targets are needed for pancreatic ductal adenocarcinoma (PDAC), a leading cause of cancer-related death worldwide. Phospholipase D (PLD) is a lipid-signaling enzyme that appears to play a critical role in cell proliferation, survival/apoptosis, and downstream oncogenic transformation. Elevated PLD1 or PLD2 (the two classical mammalian isoforms) activity has been shown to promote tumor progression in various cancer types, however, the role and mechanisms of PLD in pancreatic cancer are not yet understood. Thus, the objective is to determine the role of PLD1 regulation in pancreatic carcinogenesis through genetic and pharmacological inhibition. To evaluate the role of PLD1 in tumor growth, we subcutaneously transplanted human MIA PaCa-2 pancreatic cancer cells expressing endogenous PLD1 levels (Ctr KD cells), or MIA PaCa-2 cells in which PLD1 was knocked down (Pld1 KD cells), into immunodeficient nude mice. After 18 days post implantation, tumors that arose from Pld1-KD cells presented a significantly smaller tumor size (p<0.05) and had reduced levels of Bcl-xL and Bcl-2, compared to controls (Ctr KD). Then, to assess the role of PLD1 in the tumor microenvironment, we implanted KPC pancreatic cancer cells into C57BL/6 wild-type (WT) or C57BL/6 PLD1 knockout (Pld1−/−) mice with and without treatment with gemcitabine. Fourteen days after tumor implantation, the growth of KPC tumors was attenuated in Pld1−/− mice by 49% (p<0.05). Treatment with gemcitabine reduced tumor growth by 51.6% (p<0.05) in WT mice and by 79.5% (p<0.03) in Pld1−/− mice. Moreover, we evaluated the effects of PLD1 genetic ablation by crossing LSL-KrasG12D/+; Ptf1Cre/+ (KC) mice into PLD1 knockout (Pld1−/−) mice to generate KC; Pld1−/− mice. At 8 months of age, KC; Pld1−/− mice had significantly smaller pancreases (p<0.05) compared to KC mice. Interestingly, PLD1 ablation increased phosphorylation of ERK and c-Jun in KC; Pld1−/− mice compared to KC mice. Finally, to assess whether pharmacological inhibition of PLD can inhibit pancreatic carcinogenesis, KC mice received daily intraperitoneal injections of a small molecule inhibitor of PLD1 and PLD2 (FIPI) at a dosage of 3 mg/kg of body weight for a duration of 5 weeks. Treatment with FIPI reduced acinar-to-ductal metaplasia (p<0.05) and reduced cell proliferation (p<0.01), when compared to vehicle-treated KC controls. Additionally, FIPI treatment was safe demonstrating no significant differences in body weight between the groups and no significant alteration in the serum levels of liver enzymes, including aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase. In conclusion, these findings reveal PLD1 plays a critical role in pancreatic carcinogenesis and might represent a novel therapeutic target. Citation Format: Hala Amer Addassi, Karen Matsukuma, Gerardo G. Mackenzie. Inhibiting phospholipase D1 reduces pancreatic carcinogenesis in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3356.

Mechanical activation of TWIK-related potassium channel by nanoscopic movement and rapid second messenger signaling

Rapid conversion of force into a biological signal enables living cells to respond to mechanical forces in their environment. The force is believed to initially affect the plasma membrane and then alter the behavior of membrane proteins. Phospholipase D2 (PLD2) is a mechanosensitive enzyme that is regulated by a structured membrane-lipid site comprised of cholesterol and saturated ganglioside (GM1). Here we show stretch activation of TWIK-related K+ channel (TREK-1) is mechanically evoked by PLD2 and spatial patterning involving ordered GM1 and 4,5-bisphosphate (PIP2) clusters in mammalian cells. First, mechanical force deforms the ordered lipids, which disrupts the interaction of PLD2 with the GM1 lipids and allows a complex of TREK-1 and PLD2 to associate with PIP2 clusters. The association with PIP2 activates the enzyme, which produces the second messenger phosphatidic acid (PA) that gates the channel. Co-expression of catalytically inactive PLD2 inhibits TREK-1 stretch currents in a biological membrane. Cellular uptake of cholesterol inhibits TREK-1 currents in culture and depletion of cholesterol from astrocytes releases TREK-1 from GM1 lipids in mouse brain. Depletion of the PLD2 ortholog in flies results in hypersensitivity to mechanical force. We conclude PLD2 mechanosensitivity combines with TREK-1 ion permeability to elicit a mechanically evoked response.

Mechanical activation of TWIK-related potassium channel by nanoscopic movement and rapid second messenger signaling.

Rapid conversion of force into a biological signal enables living cells to respond to mechanical forces in their environment. The force is believed to initially affect the plasma membrane and then alter the behavior of membrane proteins. Phospholipase D2 (PLD2) is a mechanosensitive enzyme that is regulated by a structured membrane-lipid site comprised of cholesterol and saturated ganglioside (GM1). Here we show stretch activation of TWIK-related K+ channel (TREK-1) is mechanically evoked by PLD2 and spatial patterning involving ordered GM1 and 4,5-bisphosphate (PIP2) clusters in mammalian cells. First, mechanical force deforms the ordered lipids, which disrupts the interaction of PLD2 with the GM1 lipids and allows a complex of TREK-1 and PLD2 to associate with PIP2 clusters. The association with PIP2 activates the enzyme, which produces the second messenger phosphatidic acid (PA) that gates the channel. Co-expression of catalytically inactive PLD2 inhibits TREK-1 stretch currents in a biological membrane. Cellular uptake of cholesterol inhibits TREK-1 currents in culture and depletion of cholesterol from astrocytes releases TREK-1 from GM1 lipids in mouse brain. Depletion of the PLD2 ortholog in flies results in hypersensitivity to mechanical force. We conclude PLD2 mechanosensitivity combines with TREK-1 ion permeability to elicit a mechanically evoked response.

Knockout of a PLD gene in Schizochytrium limacinum SR21 enhances docosahexaenoic acid accumulation by modulation of the phospholipid profile

BackgroundThe hydrolysis and transphosphatidylation of phospholipase D (PLD) play important roles in the interconversion of phospholipids (PLs), which has been shown to profoundly impact lipid metabolism in plants. In this study, the effect of the PLD1 gene of Schizochytrium limacinum SR21 (S. limacinum SR21) on lipid metabolism was investigated.ResultsPLD1 knockout had little impact on cell growth and lipid production, but it significantly improved the percentage of polyunsaturated fatty acids in lipids, of which docosahexaenoic acid (DHA) content increased by 13.3% compared to the wild-type strain. Phospholipomics and real-time quantitative PCR analysis revealed the knockout of PLD1 reduced the interexchange and increased de novo synthesis of PLs, which altered the composition of PLs, accompanied by a final decrease in phosphatidylcholine (PC) and an increase in phosphatidylinositol, lysophosphatidylcholine, and phosphatidic acid levels. PLD1 knockout also increased DHA content in triglycerides (TAGs) and decreased it in PLs.ConclusionsThese results indicate that PLD1 mainly performs the transphosphatidylation activity in S. limacinum SR21, and its knockout promotes the migration of DHA from PLs to TAGs, which is conducive to DHA accumulation and storage in TAGs via an acyl CoA-independent pathway. This study provides a novel approach for identifying the mechanism of DHA accumulation and metabolic regulation strategies for DHA production in S. limacinum SR21.

Study on the expression changes of lncRNA in patients with systemic lupus erythematosus and its correlation with Treg cells.

We initially explored the link between the differentially expressed long non-coding RNAs (lncRNAs) and the number of regulatory T (Treg) cells by detecting the lncRNA expression profiles in patients with systemic lupus erythematosus (SLE), then analyzed the correlation between Treg-related lncRNAs and the clinical features of SLE patients, predicting the mechanism by which lncRNAs regulate the differentiation and development of Treg cells, and provided new ideas for the treatment of SLE. Peripheral blood of 9 active SLE patients were collected and mononuclear cells (PBMCs) were extracted; the lncRNA expression profiles of PBMCs were analyzed by whole transcriptome sequencing. Nine healthy people were used as controls to screen the differentially expressed lncRNAs, to analyze the correlation between lncRNAs and Treg cell number. Pearson test was used to analyze the correlation between lncRNAs and the number of Treg cell, and the correlation between Treg-associated lncRNA and SLEDAI score, ESR, C3, and C4 in SLE patients. The targeted genes of Treg-associated lncRNAs were predicted with miRcode and Targetscan databases and coexpression network. There were 240 differentially expressed lncRNAs in SLE patients compared with healthy controls, including 134 highly expressed lncRNAs (p < 0.05) and 106 lowly expressed lncRNAs (p < 0.05). The expression of ANKRD44-AS1 (r = 0.7417, p = 0.0222), LINC00200 (r = 0.6960, p = 0.0373), AP001363.2 (r = 0.7766, p = 0.0138), and LINC02824 (r = 0.7893, p = 0.0114) were positively correlated with the number of Treg cell, and the expression of AP000640.1 (r = - 0.7225, p = 0.0279), AC124248.1 (r = - 0.7653, p = 0.0163), LINC00482 (r = - 0.8317, p = 0.0054), and MIR503HG (r = - 0.7617, p < 0.05) were negatively correlated with the number of Treg cell. Among these Treg-associated lncRNAs, the expression of LINC00482 (r = - 0.7348, p < 0.05) and MIR503 HG (r = - 0.7617, p < 0.05) were negatively correlated with C3. LINC00200, ANKRD44 - AS1, and AP000640.1 related to Treg cells regulate the expression of signal transducer and activator of transcription 5 (STAT5), phospholipase D1 (PLD1), homeodomain-only protein X (HOPX), and runt-related transcription factor 3 (RUNX3) through competitive binding of miRNA or trans-regulatory mechanism, thereby regulating the differentiation and development of Treg cell. The lncRNA expression profiles were changed in SLE patients, the differentially expressed lncRNAs were associated with abnormal number and function of Treg cells in SLE, and Treg-associated lncRNAs were associated with SLE-disease activity, which may affect the expression of STAT5, PLD1, HOPX, RUNX3 and regulate Treg cell function and participate in the pathogenesis and progression of SLE by competitively binding to miRNAs or trans-regulatory mechanism. Key points • Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple organs and systems. lncRNAs may affect Treg cells function by regulating genes expression, which may be an important pathogenesis of SLE. • This study, taking SLE as an example, preliminarily analyzed the correlation between lncRNA and Treg cells in SLE patients, analyzed the correlation between Treg-related lncRNA and the clinical characteristics of SLE, and speculated that lncRNA could regulate the differentiation and development of Treg cells through competitive combination with miRNA or trans-regulatory mechanisms. • It is possible to target epigenetic therapy for SLE.

Enhanced Risky Choice in Male Rats Elicited by the Acute Pharmacological Stressor Yohimbine Involves Prefrontal Dopamine D1 Receptor Activation.

Acute stress alters risk-based decision-making; however, the underlying neural and neurochemical substrates are underexplored. Given their well-documented stress-inducing effects in humans and laboratory animals, glucocorticoids such as cortisol and corticosterone and the α2-adrenoceptor antagonist yohimbine represent potent pharmacological tools to mimic some characteristics of acute stress. Here, we analyzed the effects of the pharmacological stressors corticosterone and yohimbine given systemically on risk-based decision-making in male rats. Moreover, we investigated whether pharmacological stressor effects on risk-based decision-making involve dopamine D1 receptor stimulation in the dorsal prelimbic cortex (PL). We used a risk discounting task that requires choosing between a certain/small reward lever that always delivered 1 pellet and a risky/large reward lever that delivered 4 pellets with a decreasing probability across subsequent trials. Systemic administration of yohimbine increased the preference for the risky/large reward lever. By contrast, systemic single administration of corticosterone did not significantly promote risky choice. Moreover, co-administration of corticosterone did not enhance the effects of yohimbine on risky choice. The data further show that the increased preference for the risky/large reward lever under systemic yohimbine was lowered by a concurrent pharmacological blockade of dopamine D1 receptors in the PL. Our rodent data provide causal evidence that stimulation of PL D1 receptors may represent a neurochemical mechanism by which the acute pharmacological stressor yohimbine, and possibly nonpharmacological stressors as well, promote risky choice.

Clinical phenotype and genetic analysis of a fetus with Cardiac valvular dysplasia type 1

To explore the genetic basis for a fetus with Cardiac valvular dysplasia type 1 (CVDP1). A CVDP1 fetus identified at the Ningbo Women and Children's Hospital on July 7, 2022 was selected as the study subject. Clinical data of the fetus was collected. The fetus and its parents were subjected to trio-whole exome sequencing (trio-WES), and candidate variants were verified by Sanger sequencing. The fetus had exhibited generalized edema, complex cardiac malformation, abdominal effusion, and enhanced intestinal and renal parenchymal echoes. Trio-WES revealed that it has harbored compound heterozygous variants of the PLD1 gene, namely c.2977C>T (p.R993*) and c.1460G>A (p.W487*), which were respectively inherited from its father and mother. Neither variant was reported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.2977C>T (p.R993*) variant was evaluated to be likely pathogenic (PVS1_Moderate+PM2_Supporting+PM3+PP4), whilst the c.1460G>A (p.W487*) variant was evaluated to be pathogenic (PVS1+PM2_Supporting+PP4). The c.2977C>T (p.R993*) and c.1460G>A (p.W487*) compound heterozygous variants of the PLD1 gene probably underlay the CVDP1 in the fetus. Above discovery has enriched the mutational spectrum of the PLD1 gene and provided a guidance for genetic counseling and prenatal diagnosis in this family.

β-Hydroxy-β-methylbutyrate (HMB) leads to phospholipase D2 (PLD2) activation and alters circadian rhythms in myotubes.

β-Hydroxy-β-methylbutyrate (HMB) is a breakdown product of leucine, which promotes muscle growth. Although some studies indicate that HMB activates AKT and mTOR, others show activation of the downstream effectors, P70S6K and S6, independent of mTOR. Our aim was to study the metabolic effect of HMB around the circadian clock in order to determine more accurately the signaling pathway involved. C2C12 myotubes were treated with HMB and clock, metabolic and myogenic markers were measured around the clock. HMB-treated C2C12 myotubes showed no activation of AKT and mTOR, but did show activation of P70S6K and S6. Activation of P70S6K and S6 was also found when myotubes were treated with HMB combined with metformin, an indirect mTOR inhibitor, or rapamycin, a direct mTOR inhibitor. The activation of the P70S6K and S6 independent of AKT and mTOR, was accompanied by increased activation of phospholipase D2 (PLD). In addition, HMB led to high amplitude and advanced circadian rhythms. In conclusion, HMB induces myogenesis in C2C12 by activating P70S6K and S6 via PLD2, rather than AKT and mTOR, leading to high amplitude advanced rhythms.