Cellular & Molecular Biology Letters最新文献

Background: Age-dependent accumulation of lipofuscin in the retinal pigment epithelium (RPE) is closely related to the etiology of autosomal recessive Stargardt's disease (STGD1) and dry age-related macular degeneration (AMD). N-retinylidene-N-retinylethanolamine (A2E) is a leading component of RPE lipofuscin that is highly susceptible to blue light. Ferroptosis is an iron-dependent form of non-apoptotic cell death characterized by the accumulation of lipid peroxides to a lethal level, which plays an important role in retinal diseases. However, it remains unknown whether A2E functions as a physiological trigger for eliciting blue light-induced ferroptosis of RPE cells.

Methods: A2E-loaded RPE cells and Abca4^-/-Rdh8^-/- mice were exposed to blue light, respectively. Western blotting, immunofluorescence staining, reactive oxygen species (ROS) staining, intracellular iron staining, lipid peroxidation staining, fundus imaging, optical coherence tomography (OCT), hematoxylin-eosin (HE) staining, and electroretinography (ERG) were utilized to elucidate the role of blue light in A2E induced ferroptosis in the RPE and its potential mechanisms.

Results: Exposure of A2E to blue light promoted ferroptotic cell death in RPE cells by elevating ferrous ion (Fe²⁺) levels and inhibiting the solute carrier family 7 membrane 11 (SLC7A11)-glutathione (GSH)-glutathione peroxidase 4 (GPX4) axis. GPX4 inactivation and ROS generated by Fe²⁺ overload and GSH depletion precipitated lipid peroxidation and subsequent ferroptosis in A2E-containing RPE cells upon exposure to blue light. In addition to GSH supplement, repressing either Fe²⁺ by deferiprone (DFP) or lipid peroxidation with ferrostatin-1 (Fer-1) significantly protected RPE cells against ferroptosis caused by blue light illumination of A2E. Abca4^-/-Rdh8^-/- mice featured by an accelerated deposition of A2E in the RPE is an animal model for STGD1 and dry AMD. It was observed that ferroptosis was indeed present in the RPE of Abca4^-/-Rdh8^-/- mice following exposure to blue light. Notably, alleviating ferroptosis by intraperitoneally injected Fer-1 effectively rescued retinal function and ameliorated RPE/photoreceptor degeneration in blue light-exposed Abca4^-/-Rdh8^-/- mice.

Conclusions: Our results suggest the importance of blue light in A2E-mediated ferroptosis in the RPE, and deeply broaden the understanding of mechanisms underlying RPE atrophy arising from lipofuscin accumulation in STGD1 and dry AMD.

Background: Cyclophosphamide (CTX) is the first-line medication for the treatment of breast cancer, although it potentially leads to severe ovarian dysfunction and even premature ovarian failure (POF). However, the mechanism of CTX-induced POF remains unclear. Mesenchymal stem cell-based therapy has been wildly used for treating numerous diseases. Therefore, our study aims to elucidate the underlying mechanism of CTX-induced POF and to explore the therapeutic effect of human urine stem cells (hUSCs) in POF.

Methods: CTX-induced POF or ovarian granulosa cell (GCs) apoptosis were treated with hUSCs and their exosomes in vitro and in vivo. Morphological, histological, and functional alternations were examined using multiple approaches. The effector molecules of hUSC-derived exosomes (hUSC-Exo) were determined by differential expression analysis in the ovaries. The target genes of miRNA were accessed by transcriptome sequencing in GCs, and the underlying mechanisms were further elucidated.

Results: hUSCs remarkably inhibited CTX-induced apoptosis and promoted the proliferation of GCs, respectively. In addition, we observed that miR-27b-3p was highly expressed in hUSC-Exo and markedly suppressed CTX-induced GC apoptosis by specifically inhibiting the expression of SLC1A4, a serine transporter, in ovarian GCs, which, in turn, elevated the concentration of the intracellular serine by inhibiting the outflux of cellular serine. More importantly, the knockdown of SLC1A4 or simple supplementation of serine suppressed CTX-induced apoptosis of GCs. Finally, we demonstrated that CTX-induced apoptosis of ovarian GCs was essential for POF by reducing the intracellular serine concentration via elevating the expression of SLC1A4, whereas hUSCs protected against CTX-induced POF via miR-27b-3p/SLC1A4/serine axis-mediated activation of the PI3K/AKT/mTOR signaling pathway.

Conclusions: Our study suggests that hUSC-based cell therapy or simple supplementation of serine may provide an efficient therapeutic approach for the prevention and treatment of CTX-induced POF clinically.

Background: Recent studies have illuminated the complexities of treating advanced bladder cancer (BCa), underscoring the importance of comprehending its molecular mechanisms for creating novel therapies. While the role of Karyopherin a2 (KPNA2) in promoting BCa growth is established, the precise mechanism remains elusive.

Methods: To investigate the regulatory role of KPNA2 in BCa, we employed a comprehensive approach integrating clinical case data and bioinformatics analysis to evaluate the expression of KPNA2 in BCa tissues. Mechanisms promoting cancer by KPNA2 were examined using both in vivo and in vitro models.

Results: Our research reveals that miR-26b-5p acts as an anticancer factor by targeting and inhibiting KPNA2 expression. Furthermore, we have observed that the interaction between KPNA2 and Kinesin Family Member C1 (KIFC1) facilitates the transition of BCa cells into the G2/M phase, thereby promoting tumor advancement via activation of the Phosphoinositide 3-kinase (PI3K)- Protein Kinase B (AKT) pathway. Importantly, this investigation is the first to identify KPNA2 expression in exosomes originating from BCa tissues. Plasma exosomes from patients with BCa exhibited notably increased levels of KPNA2 compared with healthy controls, suggesting KPNA2 as a potential new tumor indicator. Additionally, KPNA2 from BCa cells triggered the conversion of fibroblasts into cancer-associated fibroblasts (CAFs), which secreted elevated levels of interleukin-6 (IL-6), contributing to a tumor-supporting environment.

Conclusions: These findings suggest that KPNA2 is a key gene that promotes BCa progression, can potentially be a novel tumor marker, and may serve as a new therapeutic target for BCa.

Atherosclerosis, with its complex pathogenesis, is a leading underlying cause of many cardiovascular diseases, which are increasingly prevalent in the population. Sphingolipids play an important role in the development of atherosclerosis. Key metabolites and enzymes in sphingolipid metabolism influence the pathogenesis of atherosclerosis in a variety of ways, including inflammatory responses and oxidative stress. Thus, an investigation of sphingolipid metabolism-related metabolites and key enzymes may provide novel insights and treatment targets for atherosclerosis. This review discusses various mechanisms and research progress on the relationship between various sphingolipid metabolites, related enzymes, and atherosclerosis. Finally, we look into the future research direction of phytosphingolipids.

Background: Circular (circ)RNAs have emerged as crucial contributors to cancer progression. Nonetheless, the expression regulation, biological functions, and underlying mechanisms of circRNAs in mediating hepatocellular carcinoma (HCC) progression remain insufficiently elucidated.

Methods: We identified circUCK2(2,3) through circRNA sequencing, RT-PCR, and Sanger sequencing. CircUCK2(2,3) levels were measured in two independent HCC cohorts using quantitative real-time PCR (qRT-PCR). We explored the functions of circUCK2(2,3) using gain- and loss-of-function assays. Techniques such as RNA-sequencing, RNA immunoprecipitation (RIP), polysome fractionation, RNA pulldown, dual luciferase reporter assay, inhibitors of EGFR downstream signaling, CRISPR-Cas9, and medium transfer assays were employed to investigate the regulatory mechanisms and the protumoral activities of circUCK2(2,3). Additionally, in vitro cytotoxic assays and patient-derived xenograft (PDX) models assessed the effects of circUCK2(2,3) on the cytotoxic synergy of lenvatinib and EGFR inhibitors.

Results: CircUCK2(2,3) is upregulated in HCC tissues and serves as an independent risk factor for poor recurrence-free survival. The expression of circUCK2(2,3) is independent on its host gene, UCK2, but is regulated by its upstream promoter and flanking inverted complementary sequences. Functionally, circUCK2(2,3) enhances HCC proliferation, migration, and invasion, both in vitro and in vivo. Mechanistically, by sponging miR-149-5p, circUCK2(2,3) increases CNIH4 levels, which in turn amplifies TGFα secretion, resulting in the activation of EGFR and downstream pAKT and pERK signaling pathways. Moreover, circUCK2(2,3) overexpression sensitizes HCC cells to EGFR inhibitors, and increases the synergistic cytotoxicity of combined lenvatinib and EGFR inhibitor treatment.

Conclusions: CircUCK2(2,3) regulates a novel oncogenic pathway, miR-149-5p-CNIH4-TGFα-EGFR, in HCC, presenting a viable therapeutic target and biomarker for the precision treatment of HCC.

Background: The protein cereblon (CRBN) mediates the antileukemia effect of lenalidomide (Len). Len binds to CRBN, recruits IKZF1/IKZF3, and promotes their ubiquitination and degradation, through which Len exhibits its antileukemia and antimyeloma activity. Therefore, the protein level of CRBN might affect the antiproliferative effect of Len. In this study, we explored the interactome for CRBN using proximity labeling technique TurboID and quantitative proteomics, and then investigated the antileukemia effect of Len.

Methods: The primary acute myeloid leukemia (AML) cells and AML cell lines were used to explore the functions of histone demethylase KDM5C on the antileukemia effect of Len. The cell viability and CRBN protein levels were evaluated in these cell lines. In addition, the KDM5C inhibitors were used to determine the effects of KDM5C enzymatic activity on the viability of AML cell lines.

Results: We identified that histone demethylase KDM5C was a CRBN-interacting protein. Biochemical experiments found that the CRBN-interacting protein KDM5C could stabilize CRBN and enhance the antileukemia effect of Len in an enzyme activity-independent manner. Furthermore, our studies revealed that the small-molecule compound MLN4924 could increase CRBN by elevating KDM5C.The combination of MLN4924 and Len can further increase the sensitivity of primary AML cells and AML cell lines to Len.

Conclusions: This study provides a possible strategy for a combination treatment with MLN4924 and Len for leukemia.

Shiga toxin (Stx)-induced hemolytic uremic syndrome (HUS) poses a life-threatening complication for which a definitive treatment remains elusive. To exert its cytotoxic effect on renal cells, Stx must be delivered from the infected intestines to the kidney. However, the mechanism underlying Stx delivery remains unclear. Here we pinpoint monocytes as the primary carriers responsible for transporting Stx2 to the renal region. Through single-cell sequencing analysis of Stx2-B-bound peripheral white blood cells sorted by flow cytometry, we observe that nearly all monocytes exhibit strong Stx2-B binding, whereas less than 10% of neutrophils are associated with Stx2-B, albeit with a lower affinity. Further examination of the single-cell dataset and cell binding assays suggest that monocytes likely bind to Stx2-B through the Toll-like receptor 4. Remarkably, Stx-laden monocytes demonstrate their ability to transport Stx2 to human renal glomerular endothelial cells (HRGEC), subsequently inducing apoptosis in HRGEC. In a mouse model of Stx1/2-positive EDL933 infection-induced HUS, the presence of Stx2-positive monocytes in peripheral blood and infiltrated kidney tissues was observed. Finally, depleting monocytes through the usage of a CD14 neutralizing antibody or blocking monocyte chemotaxis via inhibition of CCL2 notably mitigates kidney injury and dysfunction caused by lipopolysaccharide (LPS)/Stx2 treatment. Our findings unveil the pivotal role of monocytes in Stx delivery during STEC infection and offer a promising therapeutic approach for Stx-induced HUS.