Cellular and Molecular Life Sciences最新文献

Bacterial infections are prevalent and the major cause of morbidity and mortality in cirrhosis. Activation of human Kupffer cells (HKCs) from livers is essential for human innate immunity. Cytosolic phospholipase A2 (cPLA2) plays a crucial role in the control and balance of innate immune and inflammatory reactions. Uncharacterized is the role of cPLA2 in HKC activation by bacterial infection. This work aimed to determine the function and mechanism of cPLA2 in gram-negative bacteria (GNB)-induced HKC activation. In this study, we found that Escherichia coli (E. coli)-induced activation of HKCs led to a rise in cPLA2 mRNA and protein expression, where the ERK and NF-κB pathways were concurrently triggered. Luciferase activity of cPLA2' promoters, PLA2G4A promoters, was enhanced with the stimulation of E. coli or co-transfection with STAT3 or RelB in HKCs. E. coli massively boosted the binding activity of STAT3 and RelB to the specific regions of the PLA2G4A promoter as measured by ChIP-qPCR. The E. coli-ERK-STAT3 and E. coli-non-canonical NF-κB-RelB signaling axes were then identified using pathway inhibitors and transcription factors in the rescue experiments during E. coli-induced HKC activation. In conclusion, we discovered that cPLA2 is necessary for E. coli-induced HKC activation, and the underlying mechanism could be the transcriptional regulation of STAT3 and RelB on the PLA2G4A promoter following the ERK and non-canonical NF-κB signaling activation, implying that the regulation of cPLA2 expression via the E. coli-ERK/non-canonical NF-κB-STAT3/RelB signaling axis could be effective for controlling GNB-induced HKC activation in cirrhotic patients.

Aldosterone-producing adenoma (APA) is a leading cause of primary aldosteronism (PA), a condition marked by excessive aldosterone secretion. CYP11B2, the aldosterone synthase, plays a critical role in aldosterone biosynthesis and the development of APA. Despite its significance, encoding regulatory mechanisms governing CYP11B2, particularly its degradation, remain poorly understood. In this study, we sought to uncover novel regulators of CYP11B2 stability by conducting a siRNA screen targeting E3 ubiquitin ligases. Our results identified TRIM2 as a key negative regulator of CYP11B2, where its overexpression led to a significant reduction in CYP11B2 protein levels and a concomitant decrease in aldosterone production in adrenal tumor cells. Mechanistically, we demonstrated that TRIM2 interacts with CYP11B2 via its RBCC domain, promoting K29/48-linked polyubiquitination and destabilization of CYP11B2. Further results revealed that TRIM2 is downregulated in APA tissues, showing differential expression between the zona glomerulosa (ZG) and zona fasciculata (ZF) of normal adrenal tissue. These findings highlight TRIM2 as a novel modulator of aldosterone synthesis through CYP11B2 degradation, offering a potential therapeutic target for APA.

Chronic elevated blood pressure impinges on the functioning of multiple organs and therefore harms body homeostasis. Elucidating the protective mechanisms whereby the organism copes with sustained or repetitive blood pressure rises is therefore a topical challenge. Here we address this issue in the adrenal medulla, the master neuroendocrine tissue involved in the secretion of catecholamines, influential hormones in blood pressure regulation. Combining electrophysiological techniques with catecholamine secretion assays on acute adrenal slices from spontaneously hypertensive rats, we show that chromaffin cell stimulus-secretion coupling is remodeled, resulting in a less efficient secretory function primarily upon sustained cholinergic challenges. The remodeling is supported by revamped both cellular and tissular mechanisms. This first includes a decrease in chromaffin cell excitability in response to sustained electrical stimulation. This hallmark was observed both experimentally and in a computational chromaffin cell model, and occurs with concomitant changes in voltage-gated ion channel expression. The cholinergic transmission at the splanchnic nerve-chromaffin cell synapses and the gap junctional communication between chromaffin cells are also weakened. As such, by disabling its competence to release catecholamines in response sustained stimulations, the hypertensive medulla has elaborated an adaptive shielding mechanism against damaging effects of redundant elevated catecholamine secretion and associated blood pressure.

Cytokine storm is a hallmark for acute systemic inflammatory disease like sepsis. Intrinsic microbiome-derived short-chain fatty acid (SCFAs) like acetate modulates immune cell function and metabolism has been well studied. However, it remains poorly investigated about the effects and the underlying mechanism of exogenous acetate in acute inflammation like sepsis. Here, we observed that serum acetate accumulates in patients undergoing abdominal gastrointestinal surgery and in septic mice. Short exposure to high-dose exogenous acetate protects mice from sepsis by inhibiting glycolysis in macrophages, both in vivo and in vitro. Hypoxia-inducible factor 1 subunit alpha (HIF-1α) stabilization or overexpression reverses the decreased glycolysis and pro-inflammatory cytokine production in macrophages and abrogates acetate's protective effect in septic mice. Meanwhile, we also found acetyl-CoA synthetase-2, but not GPR41 or GPR43, plays a key role in acetate's immunosuppressive effect. Acetate transiently increases acetyl-coenzyme A production, promoting histone acetylation and decreasing acetyl-transfer to NF-κB p65. These findings suggest that short exposure to mM-level acetate inhibits macrophage immune response linked to HIF-1α-dependent glycolysis. Taken together, we demonstrate short-term exposure of exogenous acetate could regulate inflammatory responses through attenuating HIF-1α-dependent glycolysis.

The development of ground-breaking Survival Motor Neuron (SMN) replacement strategies has revolutionized the field of Spinal Muscular Atrophy (SMA) research. However, the limitations of these therapies have now become evident, highlighting the need for the development of complementary targets beyond SMN replacement. To address these challenges, here we explored, in in vitro and in vivo disease models, Stathmin-2 (STMN2), a neuronal microtubule regulator implicated in neurodegenerative diseases like Amyotrophic Lateral Sclerosis (ALS), as a novel SMN-independent target for SMA therapy. Our findings revealed that STMN2 overexpression effectively restored axonal growth and outgrowth defects in induced pluripotent stem cell-(iPSC)-derived motor neurons (MNs) from SMA patients. Intracerebroventricular administration of adeno-associated virus serotype 9 (AAV9) carrying Stmn2 cDNA significantly ameliorated survival rates, motor functions, muscular and neuromuscular junction pathological features in SMA mice, mirrored by in vitro outcomes. Overall, this pioneering study not only provides insight into the therapeutic potential of STMN2 in SMA, but also suggests its broader applications for MN diseases, marking a substantial step forward in addressing the multifaceted challenges of neurological diseases treatment.

Assisted reproductive technology (ART) pregnancies present a higher risk of singleton preterm birth than natural pregnancies, but the underlying molecular mechanism remains largely unknown. RNA m⁶A modification is a key epigenetic mechanism regulating cellular function, but the role of m⁶A modification, especially its "reader" YTHDC1, in preterm delivery remains undefined. To delineate the role and epigenetic mechanism of m⁶A modification in ART preterm delivery, the effects of YTHDC1 on trophoblastic function were evaluated by CCK-8, EdU, Transwell, and flow cytometry analyses post its overexpression or knockdown. Downstream signaling pathways of YTHDC1 were investigated by RNA-seq, and targeted mRNAs were explored by RIP-seq and MeRIP-seq. Upstream transcriptional factors of YTHDC1 were determined by ChIP-seq and luciferase reporter assays. Elevated YTHDC1 was detected in human ART-conceived preterm placentas and in murine preterm placentas post estradiol (E2) exposure. In vitro experiments showed that YTHDC1 promoted trophoblastic cell proliferation and migration, but inhibited cell apoptosis. Mechanistically, E2 was proven to upregulate YTHDC1 expression via retinoid X receptor alpha (RXRA) in trophoblastic cells. Enhanced YTHDC1 expression augmented the translation of RPL37 in an m⁶A-dependent manner by binding to m⁶A-modified RPL37 mRNA and concomitantly promoted the overall translational output. Importantly, administration of siRNA targeting YTHDC1 effectively delayed the progression of preterm delivery. In conclusion, the identified E2/RXRA/YTHDC1/RPL37 axis provides new insights into the epigenetic mechanism underlying ART-associated preterm delivery. The findings offer a potential prognostic biomarker and therapeutic target for preterm delivery.

Varicella-zoster virus (VZV) infection downregulates surface major histocompatibility complex class I (MHC-I) expression and retains MHC-I in the Golgi complex of infected cells. However, the underlying mechanism is not fully understood. The VZV IE4 protein is a multifunctional protein that is essential for VZV infection. In this study, the human leucocyte antigen C (HLA-C) protein was identified as a novel cellular factor associated with IE4. Ectopically expressed IE4 co-localizes with HLA-C, sequesters HLA-C to the Golgi complex and downregulates cellular surface MHC-I. VZV, with a mutated Golgi localization signal in IE4, denoted as mutated IE4 (mIE4) VZV, was constructed. In mIE4 VZV-infected cells, the cellular surface MHC-I was restored, and HLA-C was not retained in the Golgi complex. In summary, for the first time, we demonstrate a novel role of VZV IE4 in interfering with the MHC-I presentation pathway, suggesting that it may contribute to the evasion of host antiviral adaptive immunity.

About one in six couples experience fertility problems, and male infertility accounts for about half of these cases. Spermatogenesis originates from a small pool of spermatogonial stem cells (SSCs), which are of interest for the treatment of infertility but remain poorly characterised in humans. Using multiparametric spectral flow cytometric analysis with a 16-colours (16-C) panel of cell markers, we identify novel markers of SSCs and provide insights into unravelling and resolving the heterogeneity of the human spermatogonial cells. This 16-C panel of markers allowed the identification of a primitive SSCs state with the β2M^-CD51/61^-ITGA6⁺SSEA4⁺TSPAN33⁺THY1⁺CD9^medEPCAM^medCD155⁺CD148⁺CD47^highCD7^high phenotype, with a profile close to the most primitive SSCs states 0 and SSC1-B previously defined by sc-RNAseq approach. The hierarchy of events in the spermatogonial stem cell and progenitor compartment of human spermatogenesis can be delineated. This highlights the importance of a multi-parametric and spectral cytometry approach. The in-depth characterisation of testicular cells should help to overcome the lack of stem cell knowledge, that hinders the understanding of the regenerative potential of SSCs, and is a critical parameter for the successful development of new SSCs-based cell therapies.