The FASEB Journal最新文献

Meniere's disease (MD) is an inner ear disease characterized by endolymphatic hydrops (EH). Maintaining a regular daily routine is crucial for MD patients. However, the relationship between circadian rhythms and MD remains unclear. Therefore, we investigated the effect of circadian rhythm on endolymphatic hydrops and its underlying mechanisms. Mice with endolymphatic hydrops were subjected to chronic jet lag (CJL) conditions to simulate the MD patients under circadian rhythm disruptions. We assessed whether this disruption would exacerbate inner ear damage with endolymphatic hydrops. RNA-seq of the inner ear and bioinformatic analysis were performed. Then, the expression of PER2, AQP2, AQP4, AQP5, and BDNF were assessed, and the morphological changes were evaluated in the inner ear. Our findings showed circadian rhythm disruption affected the cochlear internal clock genes in the inner ear, particularly in mice with EH. EH mice under CJL conditions exhibited exacerbated hearing impairment and an increased severity of EH. GO enrichment analysis revealed that the regulation of fluid homeostasis and neurotransmitter release at synapses were significantly enriched. Disruption of circadian rhythms disturbed the expression pattern of PER2, reduced BDNF levels, and affected the expression of aquaporins in the cochlea. Moreover, the disruption of circadian rhythm compromised inner hair cell synapses and auditory nerve fibers. This study indicated that disruption of circadian rhythms may exacerbate inner ear damage in endolymphatic hydrops mice by affecting the aquaporins and compromising synapses and auditory nerves in the inner ear. BDNF and PER2 may play a central role in these pathophysiological processes.

Osteoarthritis (OA) is characterized by articular cartilage degeneration, leading to pain and loss of joint function. Recent studies have demonstrated that omega-3 (ω3) polyunsaturated fatty acid (PUFA) supplementation can decrease injury-induced OA progression in mice fed a high-fat diet. Furthermore, PUFAs have been shown to influence the mechanical properties of chondrocyte membranes, suggesting that alterations in mechanosensitive ion channel signaling could contribute to the mechanism by which ω3 PUFAs decreased OA pathogenesis. Here, we hypothesized that PUFAs may alter mechanical signaling through PIEZO1 (activated by changes in membrane tension) and TRPV4 (activated by physiologic mechano-osmotic signals), as these mechanosensitive cation channels have been shown to influence OA progression. Our results demonstrated that PUFAs reduced chondrocyte sensitivity to single-cell mechanical compression and to pharmacologic agonists of PIEZO1 and TRPV4, with ω3 PUFAs having the most significant effects overall. We also found that supplementation with ω6 PUFA linoleic acid (LA) altered the biophysical properties of chondrocytes, as evidenced by increased intracellular lipid droplet formation and more rapid membrane rupture in response to hypo-osmotic shock, suggesting that LA increases chondrocyte membrane susceptibility to damage. Our findings underscore the differential impacts of specific PUFAs on chondrocyte signaling and membrane properties and provide important considerations in the development of nutritional interventions to prevent or treat OA.

Ping X, Li Q, Ding M, et al. Effects of hypoxic compound exercise to promote HIF-1α expression on cardiac pumping function, sleep activity behavior, and exercise capacity in Drosophila. FASEB J. 2024;38(5):e23499.

In the Acknowledgements section of the original article, the number (3371182) regarding the NSF grant is incorrect; the correct number is (32371182). All those involved in the publication of the article are aware of this issue and there is no conflict of interest.

Neutrophils are peripheral blood-circulating leukocytes that play a pivotal role in host defense against bacterial pathogens which upon activation, they release web-like chromatin structures called neutrophil extracellular traps (NETs). Here, we analyzed and compared the importance of myeloid differentiation factor 88 (MYD88), peptidyl arginine deiminase 4 (PAD4), and gasdermin D (GSDMD) for NET formation in vivo following sepsis and neutrophilia challenge. Injection of lipopolysaccharide (LPS)/E. coli or the transgenic expression of granulocyte colony-stimulating factor (G-CSF), each induced NET-mediated lethal vascular occlusions in mice with combined genetic deficiency in Dnase1 and Dnase1l3 (D1/D1l3^−/−). In accordance with the signaling of toll-like receptors, Myd88/D1/D1l3^−/− animals were protected from the formation of lethal intravascular NETs during septic conditions. However, this protection was not observed during neutrophilia. It was unexpected to find that both Gsdmd/D1/D1l3^−/− and Pad4/D1/D1l3^−/− mice were fully capable of forming NETs upon LPS/E.coli challenge. Sepsis equally triggered a similar inflammatory response in these mice characterized by formation of DNA-rich thrombi, vessel occlusions, and mortality from pulmonary embolism, compared to D1/D1l3^−/− mice. Pharmacologic GSDMD inhibitors did not reduce PMA-stimulated NET formation in ex vivo models either. Similarly, neither Pad4 nor GSDMD deficiency affected intravascular occlusive NET formation upon neutrophilia challenge. The magnitude of NET production, multi-organ damage, and lethality were comparable to those observed in challenged control mice. In conclusion, our data indicate that NET formation during experimental sepsis and neutrophilia is regulated by distinct stimulus-dependent pathways that may be independent of canonical PAD4 and GSDMD.

Acute liver failure (ALF) is a life-threatening condition that occurs when the liver sustains severe damage and rapidly loses its function. The primary cause of ALF is the overdose of acetaminophen (APAP), and its treatment is relatively limited. The involvement of the complement system in the development of ALF has been implicated. However, the related mechanisms remain poorly understood. Complement 3 (C3) knockout mice, complement 3a receptor (C3aR) knockout mice, platelet C-type lectin-like receptor 2 (Clec-2)–deficient mice, and myeloid cell podoplanin (Pdpn)-deficient mice were generated. Liver tissues were collected for histological analysis, RNA sequencing, confocal immunofluorescence, and immunoblot analyses. Our data demonstrated that APAP activated the C3/C3aR pathway, leading to intrahepatic hemorrhage, ultimately resulting in hepatocyte necrosis. Deletion of C3 or C3aR mitigated APAP-induced liver injury (AILI). C3/C3aR signaling upregulated the expression and phosphorylation of transcription factors STAT3 and c-Fos in hepatic Kupffer cells, which in turn increased PDPN expression, promoting platelet recruitment to the Kupffer cells via the interaction of PDPN and the CLEC-2 on platelets. Since the activation of platelets mediated by C3/C3aR occurs irrespective of the major hemostatic pathways, blocking the C3/C3aR pathway in ALF could be a coagulopathy-sparing and novel therapeutic approach. In summary, this study unveiled the critical roles of the C3/C3aR pathway in developing AILI, providing evidence that the C3/C3aR pathway could be an effective therapeutic target for AILI.

Bromodomain-containing protein 4 (BRD4) plays a vital role in fibrosis of various organs. However, the underlying mechanism of BRD4 in renal fibrosis remains unclear. To construct in vitro and in vivo models of renal fibrosis, TCMK-1 cells were subjected to TGF-β1 treatment and mice were subjected to UUO surgery and adenine induction. IP assay was used for arginine asymmetric dimethylation (ADMA) level, ubiquitination degradation of Snail, and acetylation level of Snail test. Co-IP was used to validate the interactions of BRD4, protein arginine methyltransferase-1 (PRMT1), and Snail. HE staining and Masson staining were used for morphological examination of renal tissue. BRD4 was abnormally overexpressed during renal fibrosis. TGF-β1-induced fibrosis and partial epithelial–mesenchymal transition (pEMT) could be inhibited by BRD4 silencing. PRMT1 mediated ADMA level of BRD4 to enhance BRD4 phosphorylation and its protein stability. Snail protein degradation was attenuated by BRD4 overexpression in an acetylation-dependent manner in TCMK-1 cells. Furthermore, PRMT1 inhibitor abolished BRD4 overexpression-induced fibrosis and pEMT in TGF-β1-treated TCMK-1 cells and Snail overexpression reversed BRD4 silencing-induced inhibition of fibrosis and pEMT. What's more, the reduction of BRD4 arginine methylation inhibited BRD4 phosphorylation and Snail expression to alleviate renal fibrosis in UUO surgery and adenine induction mice. Collectively, PRMT1-mediated BRD4 arginine methylation and phosphorylation promoted pEMT and renal fibrosis through regulation of Snail expression.

At the maternal-fetal interface, tightly regulated levels of retinoic acid (RA), the physiologically active metabolite of vitamin A, are required for embryo implantation and pregnancy success. Herein, we utilize mouse models, primary human cells, and pharmacological tools to demonstrate how depletion of RA signaling via RA receptor (RAR) disrupts implantation and progression of early pregnancy. To inhibit RAR signaling during early pregnancy, BMS493, an inverse pan-RAR agonist that prevents RA-induced differentiation, was administered to pregnant mice during the peri-implantation period. Attenuation of RA/RAR signaling prior to embryo implantation results in implantation failure, whereas attenuation of RA/RAR signaling after embryo implantation disrupts the post-implantation decidual vasculature and results in pregnancy failure by mid-gestation. To inhibit RAR signaling during human endometrial stromal cell (HESC) decidualization, primary HESCs and decidualized primary HESCs were transfected with silencing RNA specific for human RARA. Inhibition of RA/RARA signaling prevents initiation of HESC decidualization, but not maintenance of the decidualized HESC phenotype. These data show that RA/RAR signaling is required for maintenance of the decidual vasculature that supports early pregnancy in mice, and distinct RAR signaling is required for initiation, but not maintenance of primary HESC decidualization in vitro.

Aging is a risk factor for several chronic conditions, including intervertebral disc degeneration and associated back pain. Disc pathologies include loss of reticular-shaped nucleus pulposus cells, disorganization of annulus fibrosus lamellae, reduced disc height, and increased disc bulging. Sonic hedgehog, cytokeratin 19, and extracellular matrix proteins are markers of healthy disc. Preclinical murine models help understand cellular and molecular mechanisms of disc pathologies and the associated neurological symptoms. Klotho (Kl) is a known anti-aging gene. Kl-deficient mice (Kl^Kl/Kl^Kl) have a reduced lifespan and display accelerated aging phenotypes in several tissues, including the kidney, pancreas, bone, and brain. To test the suitability of Kl^Kl/Kl^Kl mice for studying accelerated disc pathologies, we characterized the lumbar discs of eight-week-old Kl^Kl/Kl^Kl mice compared to wild-type controls. No structural, morphological, or molecular differences were observed in the discs of Kl^Kl/Kl^Kl mice compared to controls. Next, we tested the hypothesis that Kl^Kl/Kl^Kl mice do not display accelerated disc pathologies due to the absence of Kl expression or response by disc cells. Multiplex qPCR analysis did not detect any Kl isoforms in the disc cells, explaining the absence of disc phenotype in Kl^Kl/Kl^Kl mutants.

Retinal pathological angiogenesis (PA) is a common hallmark in proliferative retinopathies, including age-related macular degeneration (AMD), proliferative diabetic retinopathy (PDR), and retinopathy of prematurity (ROP). The mechanisms underlying PA is complex and incompletely understood. In this study, we investigated the role of extracellular matrix (ECM) protein biglycan (BGN) in PA using an oxygen-induced retinopathy (OIR) mouse model, along with hypoxia (1% O₂) conditions for incubating pericytes and endothelial cells in vitro. We found a significant upregulation of Bgn in the retinas of OIR mice. Intravitreal injection of Bgn-specific small interfering RNA (siRNA) in OIR mice at postnatal day 12 (P12) effectively curbed retinal PA at P17. Using cultured cells, we found that BGN expression in pericytes was highly sensitive to hypoxic stimulation compared to endothelial cells. We further showed that BGN stimulated retinal PA via the upregulation of C-X-C motif chemokine ligand 12 (CXCL12). Inhibition of the CXCL12-CXCR4 axis effectively diminished PA in OIR mouse. In conclusion, our study demonstrated the stimulatory role of BGN in retinal PA, identified the link between BGN and CXCL12 expression, and further highlighted the role of pericytes in retinal PA.

Molecular chaperones play critical roles in post-translational maintenance in protein homeostasis. Previous studies have shown that loss of Smyd1b function results in defective myofibril organization and dramatic upregulation of heat shock protein gene (hsp) expression in muscle cells of zebrafish embryos. To investigate the molecular mechanisms and functional importance of this stress response, we characterized changes of gene expression in smyd1b knockdown and knockout embryos using RNA-seq. The results showed that the top upregulated genes encode mostly cytosolic heat shock proteins. Co-IP assay revealed that the upregulated cytosolic Hsp70s associate with myosin chaperone UNC45b which is critical for myosin protein folding and sarcomere assembly. Strikingly, several hsp70 genes also display muscle-specific upregulation in response to heat shock-induced stress in zebrafish embryos. To investigate the regulation of hsp gene upregulation and its functional significance in muscle cells, we generated heat shock factor 1 (hsf^−/-) knockout zebrafish mutants and analyzed hsp gene expression and muscle phenotype in the smyd1b^−/−single and hsf1^−/−;smyd1b^−/− double-mutant embryos. The results showed that knockout of hsf1 blocked the hsp gene upregulation and worsened the muscle defects in smyd1b^−/− mutant embryos. Moreover, we demonstrated that Hsf1 is essential for fish survival under heat shock (HS) conditions. Together, these studies uncover a correlation between Smyd1b deficiency and the Hsf1-activated heat shock response (HSR) in regulating muscle protein homeostasis and myofibril assembly and demonstrate that the Hsf1-mediated hsp gene upregulation is vital for the survival of zebrafish larvae under thermal stress conditions.