APOE4 genotype confers transcriptomic and functional alterations to primary mouse microglia

Abstract Background Astrocytes participate in innate inflammatory responses within the mammalian central nervous system (CNS). HECT domain E3 ubiquitin protein ligase 1 (HECTD1) functions during microglial activation, suggesting a connection with neuroinflammation. However, the potential role of HECTD1 in astrocytes remains largely unknown. Results Here, we demonstrated that HECTD1 was upregulated in primary mouse astrocytes after 100 ng/ml lipopolysaccharide (LPS) treatment. Genetic knockdown of HECTD1 in vitro or astrocyte-specific knockdown of HECTD1 in vivo suppressed LPS-induced astrocyte activation, whereas overexpression of HECTD1 in vitro facilitated LPS-induced astrocyte activation. Mechanistically, we established that LPS activated σ-1R-JNK/p38 pathway, and σ-1R antagonist BD1047, JNK inhibitor SP600125, or p38 inhibitor SB203580 reversed LPS-induced expression of HECTD1, thus restored LPS-induced astrocyte activation. In addition, FOXJ2 functioned as a transcription factor of HECTD1, and pretreatment of primary mouse astrocytes with BD1047, SB203580, and SP600125 significantly inhibited LPS-mediated translocation of FOXJ2 into the nucleus. Conclusions Overall, our present findings suggest that HECTD1 participates in LPS-induced astrocyte activation by activation of σ-1R-JNK/p38-FOXJ2 pathway and provide a potential therapeutic strategy for neuroinflammation induced by LPS or any other neuroinflammatory disorders.

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Alternative oxidase encoded by sequence-optimized and chemically-modified RNA transfected into mammalian cells is catalytically active

Gene Therapy ◽

10.1038/s41434-021-00235-z ◽

2021 ◽

Author(s):

Luca Giordano ◽

Manish K. Aneja ◽

Natascha Sommer ◽

Nasim Alebrahimdehkordi ◽

Alireza Seraji ◽

...

Keyword(s):

Mammalian Cells ◽

Alternative Oxidase ◽

Chemically Modified ◽

Lung Carcinoma Cells ◽

Primary Mouse ◽

Catalytically Active ◽

Human Lung Carcinoma ◽

Pulmonary Arterial ◽

Metabolic Stresses ◽

Mitochondrial Respiratory

AbstractPlants and other organisms, but not insects or vertebrates, express the auxiliary respiratory enzyme alternative oxidase (AOX) that bypasses mitochondrial respiratory complexes III and/or IV when impaired. Persistent expression of AOX from Ciona intestinalis in mammalian models has previously been shown to be effective in alleviating some metabolic stresses produced by respiratory chain inhibition while exacerbating others. This implies that chronic AOX expression may modify or disrupt metabolic signaling processes necessary to orchestrate adaptive remodeling, suggesting that its potential therapeutic use may be confined to acute pathologies, where a single course of treatment would suffice. One possible route for administering AOX transiently is AOX-encoding nucleic acid constructs. Here we demonstrate that AOX-encoding chemically-modified RNA (cmRNA), sequence-optimized for expression in mammalian cells, was able to support AOX expression in immortalized mouse embryonic fibroblasts (iMEFs), human lung carcinoma cells (A549) and primary mouse pulmonary arterial smooth muscle cells (PASMCs). AOX protein was detectable as early as 3 h after transfection, had a half-life of ~4 days and was catalytically active, thus supporting respiration and protecting against respiratory inhibition. Our data demonstrate that AOX-encoding cmRNA optimized for use in mammalian cells represents a viable route to investigate and possibly treat mitochondrial respiratory disorders.

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Pediatric MDS and bone marrow failure-associated germline mutations in SAMD9 and SAMD9L impair multiple pathways in primary hematopoietic cells

Leukemia ◽

10.1038/s41375-021-01212-6 ◽

2021 ◽

Author(s):

Melvin E. Thomas ◽

Sherif Abdelhamed ◽

Ryan Hiltenbrand ◽

Jason R. Schwartz ◽

Sadie Miki Sakurada ◽

...

Keyword(s):

Bone Marrow ◽

Bone Marrow Failure ◽

Transcriptional Profiling ◽

Hematopoietic Cells ◽

Protein Translation ◽

Germline Mutations ◽

Hematopoietic Stem ◽

Monosomy 7 ◽

Cellular Environment ◽

Primary Mouse

AbstractPediatric myelodysplastic syndromes (MDS) are a heterogeneous disease group associated with impaired hematopoiesis, bone marrow hypocellularity, and frequently have deletions involving chromosome 7 (monosomy 7). We and others recently identified heterozygous germline mutations in SAMD9 and SAMD9L in children with monosomy 7 and MDS. We previously demonstrated an antiproliferative effect of these gene products in non-hematopoietic cells, which was exacerbated by their patient-associated mutations. Here, we used a lentiviral overexpression approach to assess the functional impact and underlying cellular processes of wild-type and mutant SAMD9 or SAMD9L in primary mouse or human hematopoietic stem and progenitor cells (HSPC). Using a combination of protein interactome analyses, transcriptional profiling, and functional validation, we show that SAMD9 and SAMD9L are multifunctional proteins that cause profound alterations in cell cycle, cell proliferation, and protein translation in HSPCs. Importantly, our molecular and functional studies also demonstrated that expression of these genes and their mutations leads to a cellular environment that promotes DNA damage repair defects and ultimately apoptosis in hematopoietic cells. This study provides novel functional insights into SAMD9 and SAMD9L and how their mutations can potentially alter hematopoietic function and lead to bone marrow hypocellularity, a hallmark of pediatric MDS.

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Maresin 1 protects the liver against ischemia/reperfusion injury via the ALXR/Akt signaling pathway

Molecular Medicine ◽

10.1186/s10020-021-00280-9 ◽

2021 ◽

Vol 27 (1) ◽

Author(s):

Da Tang ◽

Guang Fu ◽

Wenbo Li ◽

Ping Sun ◽

Patricia A. Loughran ◽

...

Keyword(s):

Oxidative Stress ◽

Liver Injury ◽

Signaling Pathway ◽

Inflammatory Responses ◽

Ischemia Reperfusion ◽

Akt Signaling ◽

Akt Signaling Pathway ◽

Serum Aminotransferase ◽

Primary Mouse ◽

Maresin 1

Abstract Background Hepatic ischemia/reperfusion (I/R) injury can be a major complication following liver surgery contributing to post-operative liver dysfunction. Maresin 1 (MaR1), a pro-resolving lipid mediator, has been shown to suppress I/R injury. However, the mechanisms that account for the protective effects of MaR1 in I/R injury remain unknown. Methods WT (C57BL/6J) mice were subjected to partial hepatic warm ischemia for 60mins followed by reperfusion. Mice were treated with MaR1 (5-20 ng/mouse), Boc2 (Lipoxin A4 receptor antagonist), LY294002 (Akt inhibitor) or corresponding controls just prior to liver I/R or at the beginning of reperfusion. Blood and liver samples were collected at 6 h post-reperfusion. Serum aminotransferase, histopathologic changes, inflammatory cytokines, and oxidative stress were analyzed to evaluate liver injury. Signaling pathways were also investigated in vitro using primary mouse hepatocyte (HC) cultures to identify underlying mechanisms for MaR1 in liver I/R injury. Results MaR1 treatment significantly reduced ALT and AST levels, diminished necrotic areas, suppressed inflammatory responses, attenuated oxidative stress and decreased hepatocyte apoptosis in liver after I/R. Akt signaling was significantly increased in the MaR1-treated liver I/R group compared with controls. The protective effect of MaR1 was abrogated by pretreatment with Boc2, which together with MaR1-induced Akt activation. MaR1-mediated liver protection was reversed by inhibition of Akt. Conclusions MaR1 protects the liver against hepatic I/R injury via an ALXR/Akt signaling pathway. MaR1 may represent a novel therapeutic agent to mitigate the detrimental effects of I/R-induced liver injury.

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