The FASEB Journal最新文献

Changes in protein levels of the mammalian cleavage factor, CFIm25, play a role in regulating pathological processes including neural dysfunction, fibrosis, and tumorigenesis. However, despite these effects, little is known about how CFIm25 (NUDT21) expression is regulated at the RNA level. A potential regulator of NUDT21 mRNA are small non-coding microRNAs (miRNAs). In general, miRNAs bind to the 3′untranslated regions (3′UTRs) and can target the bound mRNA for degradation or inhibit translation thus affecting the levels of protein in cells. Interestingly, a mechanism known as alternative polyadenylation (APA) enables mRNAs to escape miRNA regulation by generating mRNAs with 3′UTRs of different sizes. As many miRNA target sites are located within the 3′UTR, shortening the 3′UTR allows mRNAs to evade miRNAs targeting this region. The differences in the lengths and the sequence composition of the 3′UTRs may also impact the mRNA's translatability and subcellular localization. APA has been reported to regulate over 70% of protein coding genes, thus increasing the transcript repertoire. Several proteins, including mammalian cleavage factor, CFIm25 (NUDT21), have been shown to regulate APA. In this study we wanted to determine whether CFIm25 (NUDT21), itself a regulator of APA, undergoes APA to evade miRNA regulation. We used the blood cancer mantle cell lymphoma (MCL) cells as a model and showed that in these cells, NUDT21 is relatively stable with a long half-life. In addition, the NUDT21 pre-mRNA undergoes alternative APA within the same terminal exon. The three different sized NUDT21 mRNAs have different 3′UTR lengths and they each use a different canonical polyadenylation signal, AAUAAA, for 3′end cleavage and polyadenylation. Use of miRNA mimics and inhibitors showed that miR-23a, miR-222, and miR-323a play a significant role in regulating NUDT21 expression. Hence, these results suggest that NUDT21 mRNA is stable and the different 3′UTRs generated through APA of NUDT21 play an important role in evading miRNA regulation and offers insights into how levels of CFIm25 (NUDT21) may be fine-tuned as needed under different physiological and pathological conditions.

Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by severe liver inflammation and fibrosis due to an imbalanced immune response caused by enhanced bacterial components. The progression of MASH is closely linked to increased permeability of intestinal mucosal barrier facilitating enter of bacterial components into hepatic portal venous system. B cells are important immune cells for adaptive responses and enhance hepatic inflammation through cytokine production and T cell activation. B cells are influenced by gut microbiota, but the specific B cell populations in MASH and their pathologic mechanism remain obscure. Here, we found that the numbers of B cells highly expressing CXCR5, the receptor of CXCL13 chemokine, were increased in the livers of MASH. CXCR5 high B cells are non-proliferating naive B cells with inflammatory features mainly residing in hepatic parenchyma to affect liver pathology. Importantly, we revealed that CXCR5 high B cells were induced by bacterial components stimulating TLRs. These bacterial stimulator-induced CXCR5^hi B cells highly express TNFα, CD80, and MHC class II, leading to T cell activation. Consistently, we confirmed that intravenous injection of CXCR5 high B cells enhanced hepatic inflammation in MASH model. Ultimately, this study elucidates the role and mechanisms of CXCR5 high B cells in advancing MASH progression.

G-Protein Coupled Receptor, Class C, Group 5, Member A (GPRC5A) has been extensively studied in lung and various epithelial cancers. Nevertheless, its role in the skin remains to be elucidated. In this study, we sought to investigate the function of this receptor in skin biology. Our research demonstrated that its expression responds to mechanical substrate changes in human primary keratinocytes. Furthermore, we observed the reinduction of GPRC5A during wound healing at the leading edges in an ex vivo burn model, coinciding with the translocation of its C-terminal region into the nucleus. We identified the cleavage site of GPRC5A by N-TAILS analysis, and cathepsin G was characterized as the protease responsible for proteolysis in cultured cells. In order to gain a deeper understanding of the role of GPRC5A in keratinocytes, we performed a GPRC5A knockdown in N/TERT-1 cells using short-hairpin RNA. Our findings indicate a strong association between GPRC5A and adhesion regulation pathways. Additionally, our results demonstrate that GPRC5A^KD enhances cell adhesion while reducing cell migration and differentiation. It is noteworthy that these effects were reversed by the addition of a recombinant polypeptide that mimics the C-terminal region of GPRC5A. In conclusion, our study reveals that GPRC5A plays an unexpected role in regulating keratinocyte behavior, with implications for its C-terminal region translocation into the nucleus. These results offer promising avenues for future research in the field of wound healing.

Following injury, skeletal muscle undergoes repair via satellite cell (SC)-mediated myogenic progression. In SCs, the circadian molecular clock gene, Bmal1, is necessary for appropriate myogenic progression and repair with evidence that muscle molecular clocks can also affect force production. Utilizing a mouse model allowing for inducible depletion of Bmal1 within SCs, we determined contractile function, SC myogenic progression and muscle damage and repair following eccentric contractile-induced injury. At baseline, SC-Bmal1^iKO animals exhibited a ~20–25% reduction in normalized force production (ex vivo and in vivo) versus control SC-Bmal1^Cntrl and SC-Bmal1^iKO untreated littermates (p < .05). Following contractile injury, SC-Bmal1^iKO animals displayed reduced muscle damage and subsequent repair post-injury (Dystrophin^negative fibers 24 h: SC-Bmal1^Cntrl 199 ± 41; SC-Bmal1^iKO 36 ± 13, p < .05) (eMHC⁺ fibers 7 day: SC-Bmal1^Cntrl 217.8 ± 115.5; SC-Bmal1^iKO 27.8 ± 17.3; Centralized nuclei 7 day: SC-Bmal1^Cntrl 160.7 ± 70.5; SC-Bmal1^iKO 46.2 ± 15.7). SC-Bmal1^iKO animals also showed reduced neutrophil infiltration, consistent with less injury (Neutrophil content 24 h: SC-Bmal1^Cntrl 2.4 ± 0.4; SC-Bmal1^iKO 0.4 ± 0.2, % area fraction, p < .05). SC-Bmal1^iKO animals had greater SC activation/proliferation at an earlier timepoint (p < .05) and an unexplained increase in activation 7 days post injury. Collectively, these data suggest SC-Bmal1 plays a regulatory role in force production, influencing the magnitude of muscle damage/repair, with an altered SC myogenic progression following contractile-induced muscle injury.

The correct synthesis and degradation of proteins are vital for numerous biological processes in the human body, with protein degradation primarily facilitated by the ubiquitin-proteasome system. The SKP1-CUL1-F-box (SCF) E3 ubiquitin ligase, a member of the Cullin-RING E3 ubiquitin ligase (CRL) family, plays a crucial role in mediating protein ubiquitination and subsequent 26S proteasome degradation during normal cellular metabolism. Notably, SCF is intricately linked to the pathogenesis of various diseases, including malignant tumors. This paper provides a comprehensive overview of the functional characteristics of SCF complexes, encompassing their assembly, disassembly, and regulatory factors. Furthermore, we discuss the diverse effects of SCF on crucial cellular processes such as cell cycle progression, DNA replication, oxidative stress response, cell proliferation, apoptosis, cell differentiation, maintenance of stem cell characteristics, tissue development, circadian rhythm regulation, and immune response modulation. Additionally, we summarize the associations between SCF and the onset, progression, and prognosis of malignant tumors. By synthesizing current knowledge, this review aims to offer a novel perspective for a holistic and systematic understanding of SCF complexes and their multifaceted functions in cellular physiology and disease pathogenesis.

EXPRESSION OF CONCERN: C. Blázquez, A. Carracedo, L. Barrado, P. J. Real, J. L. Fernández-Luna, G. Velasco, M. Malumbres, and M. Guzmán, “Cannabinoid Receptors as Novel Targets for the Treatment of Melanoma,” The FASEB Journal. 20, no. 14 (2006): 2633-2635, https://doi.org/10.1096/fj.06-6638fje

This Expression of Concern is for the above article, published online on 25 October 2006 in Wiley Online Library (wileyonlinelibrary.com), and has been published by agreement between the journal Editor-in-Chief, Loren E. Wold; the Federation of American Societies for Experimental Biology; and Wiley Periodicals LLC. This Expression of Concern has been published due to concerns raised by a third party regarding duplicated image sections and undeclared splicing within the subpanels of Figure 1A. The authors acknowledged the image compilation error, but due to the time elapsed since publication, the raw data was not available. The authors stated that their findings regarding melanoma cells expressing functional CB1 and CB2 receptors are supported by other experimental approaches shown in this article, and have been confirmed and published by other independent investigators. Therefore, the authors believe that the irregularities found in Figure 1A do not affect the results and the conclusions of this publication.

Nevertheless, without an explanation of the anomaly in the figure and in the absence of the original raw data, the journal team could not verify the authenticity of this figure. Therefore, the journal has decided to issue an Expression of Concern to inform and alert the readers.

Expression of Concern: A. Parcellier, M. Brunet, E. Schmitt, E. Col, C. Didelot, A. Hammann, K. Nakayama, K. I. Nakayama, S. Khochbin, E. Solary, and C. Garrido, “HSP27 Favors Ubiquitination and Proteasomal Degradation of p27^Kip1 and Helps S-Phase Re-Entry in Stressed Cells,” The FASEB Journal 20, no. 8 (2006): 1179–1181, https://doi.org/10.1096/fj.05-4184fje.

This Expression of Concern is for the above article, published online on April 26, 2006 in Wiley Online Library (wileyonlinelibrary.com), and has been published by agreement between the journal Editor-in-Chief, Loren E. Wold; the Federation of American Societies for Experimental Biology; and Wiley Periodicals LLC. This Expression of Concern has been published due to concerns raised by a third party regarding highly similar image sections within Figures 1A, D, E, F, and H, Figures 5A and B, Figure 7C and Figure 10A; a potential duplication between Figure 1A and Figure 10A; and unacknowledged splicings within Figure 2B, and Figures 3A and B. The authors were informed about the concerns, and they were able to provide a satisfactory explanation and partial raw data to the concerns regarding Figures 1A, 2B, 3A, 3B, and 1D. However, without an adequate explanation of the anomaly in the rest of the figures and in the absence of the original raw data, the journal team could not verify the authenticity of these figures and could not exclude that these concerns affect the related conclusions of the article. Therefore, the journal has decided to issue an Expression of Concern to inform and alert the readers.

Brown adipose tissue (BAT) is a metabolically highly active tissue that dissipates energy stored within its intracellular triglyceride droplets as heat. Others have previously utilized MRI to show that the fat fraction of human supraclavicular BAT (scBAT) decreases upon cold exposure, compared with baseline (i.e., pre-cooling). However, comparisons to a control group that was not exposed to cold are largely lacking. We recently developed a non-invasive dynamic MRI protocol that allows for quantifying scBAT fat fraction changes over time. Here, we aimed to study the effect of cold exposure versus thermoneutrality on fat fraction changes in human scBAT. Ten young (mean age: 21.5 ± 0.7 years), lean (mean BMI: 21.7 ± 0.5 kg/m²), 12 h-fasted volunteers (9 females; 1 male) underwent up to 70 consecutive MRI scans each on two separate study visits in a cross-over design. Participants were exposed to a temperature of 32°C for 10 scans (i.e., ±16 min), which was then either lowered to 18°C (i.e., cold exposure) or was maintained at 32°C (i.e., thermoneutrality). Dynamic fat fraction changes were quantified, and self-reported thermal perception scores were monitored. The fat fraction in scBAT decreased over time upon cold exposure (r = −.222, p < .001). Interestingly however, we also observed a decrease in scBAT fat fraction over time upon thermoneutrality (r = −.212, p < .001). No difference was observed between the two temperature conditions (p = .55), while self-reported thermal perception scores were consistently higher (i.e., colder) upon cold exposure. In the trapezius muscle and the humerus bone as control tissues, the fat fraction was unaffected in both temperature conditions. The fat fraction in subcutaneous white adipose tissue (sWAT) however, also decreased over time upon cold exposure (r = −.270, p < .001) and during thermoneutrality (r = −.190, p < .001), again with no difference (p = .92) between the two temperature conditions. In conclusion, our results show that in 12 h-fasted, healthy individuals cold exposure and thermoneutrality similarly reduce the fat fraction within scBAT and sWAT. While we interpret that the cold exposure was sufficient to induce thermogenesis, we suggest that an increased lipolytic activity within adipocytes, as a consequence of fasting, may be the primary cause of the decreased fat fraction in both sWAT and scBAT in our study. The current study highlights the potential influence of fasting on the fat fraction in scBAT and stresses the importance of inclusion of a thermoneutral control group in studies investigating the BAT-modulating effect of cold exposure.

Fatty acid binding proteins (FABPs) are a class of small molecular mass intracellular lipid chaperone proteins that bind to hydrophobic ligands, such as long-chain fatty acids. FABP5 expression was significantly upregulated in the N-methyl-d-aspartic acid (NMDA) model, the microbead-induced chronic glaucoma model, and the DBA/2J mice. Previous studies have demonstrated that FABP5 can mediate mitochondrial dysfunction and oxidative stress in ischemic neurons, but the role of FABP5 in oxidative stress and cell death in retina NMDA injury models is unclear. In this study, we found that FABP5 is significantly altered in a model of glutamate excitotoxicity and is regulated by Stat3. Inhibition of FABP5 alleviated oxidative stress imbalance and activation of NLRP3 inflammasome, reduced the release of inflammatory factors, and ultimately attenuated glutamate excitotoxicity-induced retinal ganglion cell loss. Meanwhile, caspase1 inhibitors could alleviate the retinal ganglion cell loss induced by glutamate excitotoxicity. In conclusion, FABP5 inhibition protects retina ganglion cells from excitotoxic damage by suppressing the ROS-NLRP3 inflammasome pathway. FABP5 maybe a promising new target for glaucoma diagnosis and treatment.

Tamoxifen is an inhibitor of estrogen receptors and was originally developed for breast cancer therapy. Besides, tamoxifen is widely used for Cre-estrogen receptor-mediated conditional knockout in transgenic mice. However, we found that the 3-month feeding of 0.5 g/kg tamoxifen diet dramatically lowered the body weight of mice. The liver fat content and the serum lipid indicators were all decreased. But the liver injuries were identified, as illustrated by liver/body ratio and serum ALT and AST levels. The Sirius red staining and α-SMA staining even showed fibrosis in the liver. The increased lipid peroxidation indicators MDA and LPO, and ferroptosis markers COX-2, GPX4, SLC7A11, and ACSL4 implied the tamoxifen-induced ferroptosis in the liver. We further found that tamoxifen induced hepatic iron deposition. The investigation of iron transporters found that tamoxifen upregulated ferric iron reductase STEAP3, ferrous iron transporter DMT1, and iron storage molecule ferritin, which were probably the reasons for tamoxifen-induced iron deposition. The downregulation of the transferrin receptor and upregulation of hepcidin were more likely the responses to iron deposition. In conclusion, we found that tamoxifen disturbed the iron metabolism and induced liver injuries and ferroptosis, warranting attention to the applications of tamoxifen in cancer therapy and conditional gene knockout.