Hydrocephalus is characterized by abnormal accumulation of cerebrospinal fluid (CSF) in the ventricular cavity. The circulation of CSF in brain ventricles is controlled by the coordinated beating of motile cilia at the surface of ependymal cells (ECs). Here, we show that MT1-MMP is highly expressed in olfactory bulb, rostral migratory stream, and the ventricular system. Mice deficient for membrane-type 1–MMP (MT1-MMP) developed typical phenotypes observed in hydrocephalus, such as dome-shaped skulls, dilated ventricles, corpus callosum agenesis, and astrocyte hypertrophy, during the first 2 weeks of postnatal development. MT1-MMP–deficient mice exhibited reduced and disorganized motile cilia with the impaired maturation of ECs, leading to abnormal CSF flow. Consistent with the defects in motile cilia morphogenesis, the expression of promulticiliogenic genes was significantly decreased, with a concomitant hyperactivation of Notch signaling in the walls of lateral ventricles in Mmp14–/– brains. Inhibition of Notch signaling by γ-secretase inhibitor restored ciliogenesis in Mmp14–/– ECs. Taken together, these data suggest that MT1-MMP is required for ciliogenesis and EC maturation through suppression of Notch signaling during early brain development. Our findings indicate that MT1-MMP is critical for early brain development and loss of MT1-MMP activity gives rise to hydrocephalus.
Zhixin Jiang, Jin Zhou, Xin Qin, Huiling Zheng, Bo Gao, Xinguang Liu, Guoxiang Jin, Zhongjun Zhou
Inflammation is a major risk factor of morbidity and mortality in older adults. Although its precise etiology is unknown, low-grade inflammation in older adults is commonly associated with increased intestinal epithelial permeability (leaky gut) and abnormal (dysbiotic) gut microbiota. The increasing older population and lack of treatments to reduce aging-related microbiota dysbiosis, leaky gut, and inflammation culminates in a rise in aging-related comorbidities, constituting a significant public health concern. Here, we demonstrate that a human-origin probiotic cocktail containing 5 Lactobacillus and 5 Enterococcus strains isolated from healthy infant gut prevented high-fat diet–induced (HFD-induced) microbiota dysbiosis, leaky gut, inflammation, metabolic dysfunctions, and physical function decline in older mice. Probiotic-modulated gut microbiota primarily reduced leaky gut by increasing tight junctions, which in turn reduced inflammation. Mechanistically, probiotics modulated microbiota in a way to increase bile salt hydrolase activity, which in turn increased taurine abundance in the gut that stimulated tight junctions and suppressed gut leakiness. Furthermore, in Caenorhabditis elegans, taurine increased life span, reduced adiposity and leaky gut, and enhanced physical function. The results suggest that such probiotic therapies could prevent or treat aging-related leaky gut and inflammation in the elderly.
Shokouh Ahmadi, Shaohua Wang, Ravinder Nagpal, Bo Wang, Shalini Jain, Atefeh Razazan, Sidharth P. Mishra, Xuewei Zhu, Zhan Wang, Kylie Kavanagh, Hariom Yadav
Bone fractures are a major cause of morbidity and mortality, particularly in patients with diabetes, who have a high incidence of fractures and exhibit poor fracture healing. Coordinated expression of osteoblast-derived vascular endothelial growth factor (VEGF) and bone morphogenic proteins (BMPs) is essential for fracture repair. The NO/cGMP/protein kinase G (PKG) signaling pathway mediates osteoblast responses to estrogens and mechanical stimulation, but the pathway’s role in bone regeneration is unknown. Here, we used a mouse cortical-defect model to simulate bone fractures and studied osteoblast-specific PKG1-knockout and diabetic mice. The knockout mice had normal bone microarchitecture but after injury exhibited poor bone regeneration, with decreased osteoblasts, collagen deposition, and microvessels in the bone defect area. Primary osteoblasts and tibiae from the knockout mice expressed low amounts of Vegfa and Bmp2/4 mRNAs, and PKG1 was required for cGMP-stimulated expression of these genes. Diabetic mice also demonstrated low Vegfa and Bmp2/4 expression in bone and impaired bone regeneration after injury; notably, the cGMP-elevating agent cinaciguat restored Vegfa and BMP2/4 expression and full bone healing. We conclude that PKG1 is a key orchestrator of VEGF and BMP signaling during bone regeneration and propose pharmacological PKG activation as a novel therapeutic approach to enhance fracture healing.
Nadine Schall, Julian J. Garcia, Hema Kalyanaraman, Shyamsundar Pal China, Jenna J. Lee, Robert L. Sah, Alexander Pfeifer, Renate B. Pilz
The TAFRO clinical subtype of idiopathic multicentric Castleman disease (iMCD-TAFRO) is a rare hematologic illness involving episodic disease flares of thrombocytopenia, anasarca, fever, reticulin myelofibrosis, renal dysfunction, and organomegaly (TAFRO) and progressive multiple organ dysfunction. We previously showed that the mTOR signaling pathway is elevated in lymph nodes of iMCD-TAFRO patients and that an mTOR inhibitor is effective in a small cohort of patients. However, the upstream mechanisms, cell types, and mediators involved in disease pathogenesis remain unknown. Here, we developed a targeted approach to identify candidate cellular drivers and mechanisms in iMCD-TAFRO through cellular and transcriptomic studies. Using paired iMCD-TAFRO PBMC samples collected during flare and remission, we identified T cell activation and alterations in NK cell and monocyte subset frequencies during iMCD-TAFRO flare. These changes were associated with increased Type I IFN (IFN-I) response gene signatures across CD8+ T cells, NK cells, and monocytes. Finally, we found that IFN-β stimulation of monocytes and T cells from iMCD-TAFRO patient remission samples induced increased mTOR activation compared with healthy donors, and this was abrogated with either mTORC1 or JAK1/2 inhibition. The data presented here support a potentially novel role for IFN-I signaling as a driver of increased mTOR signaling in iMCD-TAFRO.
Ruth-Anne Langan Pai, Alberto Sada Japp, Michael Gonzalez, Rozena F. Rasheed, Mariko Okumura, Daniel Arenas, Sheila K. Pierson, Victoria Powers, Awo Akosua Kesewa Layman, Charlly Kao, Hakon Hakonarson, Frits van Rhee, Michael R. Betts, Taku Kambayashi, David C. Fajgenbaum
Arrhythmogenic cardiomyopathy (AC) is a genetic disease causing arrhythmia and sudden cardiac death with only symptomatic therapy available at present. Mutations of desmosomal proteins, including desmoglein-2 (Dsg2) and plakoglobin (Pg), are the major cause of AC and have been shown to lead to impaired gap junction function. Recent data indicated the involvement of anti-Dsg2 autoantibodies in AC pathogenesis. We applied a peptide to stabilize Dsg2 binding similar to a translational approach to pemphigus, which is caused by anti-desmoglein autoantibodies. We provide evidence that stabilization of Dsg2 binding by a linking peptide (Dsg2-LP) is efficient to rescue arrhythmia in an AC mouse model immediately upon perfusion. Dsg2-LP, designed to cross-link Dsg2 molecules in proximity to the known binding pocket, stabilized Dsg2-mediated interactions on the surface of living cardiomyocytes as revealed by atomic force microscopy and induced Dsg2 oligomerization. Moreover, Dsg2-LP rescued disrupted cohesion induced by siRNA-mediated Pg or Dsg2 depletion or l-tryptophan, which was applied to impair overall cadherin binding. Dsg2-LP rescued connexin-43 mislocalization and conduction irregularities in response to impaired cardiomyocyte cohesion. These results demonstrate that stabilization of Dsg2 binding by Dsg2-LP can serve as a novel approach to treat arrhythmia in patients with AC.
Camilla Schinner, Bernd Markus Erber, Sunil Yeruva, Angela Schlipp, Vera Rötzer, Ellen Kempf, Sebastian Kant, Rudolf E. Leube, Thomas D. Mueller, Jens Waschke
Sjögren’s syndrome (SS) is a systemic autoimmune disease that mainly affects exocrine salivary and lacrimal glands. Local inflammation in the glands is thought to trigger glandular dysfunction and symptoms of dryness. However, the mechanisms underlying these processes are incompletely understood. Our work suggests T cell exosome–derived miR-142-3p as a pathogenic driver of immunopathology in SS. We first document miR-142-3p expression in the salivary glands of patients with SS, both in epithelial gland cells and within T cells of the inflammatory infiltrate, but not in healthy volunteers. Next, we show that activated T cells secreted exosomes containing miR-142-3p, which transferred into glandular cells. Finally, we uncover a functional role of miR-142-3p–containing exosomes in glandular cell dysfunction. We find that miR-142-3p targets key elements of intracellular Ca2+ signaling and cAMP production — sarco(endo)plasmic reticulum Ca2+ ATPase 2b (SERCA2B), ryanodine receptor 2 (RyR2), and adenylate cyclase 9 (AC9) — leading to restricted cAMP production, altered calcium signaling, and decreased protein production from salivary gland cells. Our work provides evidence for a functional role of the miR-142-3p in SS pathogenesis and promotes the concept that T cell activation may directly impair epithelial cell function through secretion of miRNA-containing exosomes.
Juan Cortes-Troncoso, Shyh-Ing Jang, Paola Perez, Jorge Hidalgo, Tomoko Ikeuchi, Teresa Greenwell-Wild, Blake M. Warner, Niki M. Moutsopoulos, Ilias Alevizos
EIF2AK4, which encodes the amino acid deficiency–sensing protein GCN2, has been implicated as a susceptibility gene for type 2 diabetes in the Japanese population. However, the mechanism by which GCN2 affects glucose homeostasis is unclear. Here, we show that insulin secretion is reduced in individuals harboring the risk allele of EIF2AK4 and that maintenance of GCN2-deficient mice on a high-fat diet results in a loss of pancreatic β cell mass. Our data suggest that GCN2 senses amino acid deficiency in β cells and limits signaling by mechanistic target of rapamycin complex 1 to prevent β cell failure during the consumption of a high-fat diet.
Ayumi Kanno, Shun-ichiro Asahara, Ayuko Furubayashi, Katsuhisa Masuda, Risa Yoshitomi, Emi Suzuki, Tomoko Takai, Maki Kimura-Koyanagi, Tomokazu Matsuda, Alberto Bartolome, Yushi Hirota, Norihide Yokoi, Yuka Inaba, Hiroshi Inoue, Michihiro Matsumoto, Kenichi Inoue, Takaya Abe, Fan-Yan Wei, Kazuhito Tomizawa, Wataru Ogawa, Susumu Seino, Masato Kasuga, Yoshiaki Kido
Therapeutic complement inhibition is a major focus for novel drug development. Of upstream targets, factor D (FD) is appealing because it circulates in plasma at low concentrations and has a single function: to cleave factor B to generate C3 convertase of the alternative pathway (AP). Mice with a targeted deletion of factor H (FH; Cfh–/– mice) develop C3 glomerulopathy (C3G) due to uncontrolled AP activity. To assess the impact of FD inhibition, we studied Cfh–/– Cfd–/– mice. We show that C3G in Cfh–/– mice is not rescued by removing FD. We used serum from Cfh–/– Cfd–/– mice to demonstrate that residual AP function occurs even when both FD and FH are missing and that hemolytic activity is present due to the action of C3(H2O). We propose that uncontrolled tick-over leads to slow activation of the AP in Cfh–/– Cfd–/– mice and that a minimal threshold of FH is necessary if tissue deposition of C3 is to be prevented. The FD/FH ratio dictates serum C3 level and renal C3b deposition. In C3G patients with chronic renal disease, the FD/FH ratio correlates inversely with C3 and C5 serum levels, suggesting that continuous AP control may be difficult to achieve by targeting FD.
Yuzhou Zhang, Adam Keenan, Dao-Fu Dai, Kristofer S. May, Emily E. Anderson, Margaret A. Lindorfer, John B. Henrich, Gabriella R. Pitcher, Ronald P. Taylor, Richard J.H. Smith
Metastatic colorectal cancer (CRC) is poorly immunogenic, with limited neoantigens that can be targeted by cancer vaccine. Previous approaches to upregulate neoantigen have had limited success. In this study, we investigated the role of a DNA methyltransferase inhibitor (DNMTi), 5-aza-2′-deoxycytidine (DAC), in inducing cancer testis antigen (CTA) expression and evaluated the antitumor efficacy of a combinatorial approach with an epigenetically regulated cancer vaccine EpiGVAX and DAC. A murine model of metastatic CRC treated with combination therapy with an irradiated whole-cell CRC vaccine (GVAX) and DAC was used to assess the antitumor efficacy. DAC significantly induced expression of CTAs in CRC, including a new CTA Tra-P1A with a known neoepitope, P1A. Epigenetically modified EpiGVAX with DAC improved survival outcomes of GVAX. Using the epigenetically regulated antigen Tra-P1A as an example, our study suggests that the improved efficacy of EpiGVAX with DAC may due in part to the enhanced antigen-specific antitumor immune responses. This study shows that epigenetic therapy with DNMTi can not only induce new CTA expression but may also sensitize tumor cells for immunotherapy. Neoantigen-based EpiGVAX combined with DAC can improve the antitumor efficacy of GVAX by inducing antigen-specific antitumor T cell responses to epigenetically regulated proteins.
Victoria M. Kim, Xingyi Pan, Kevin C. Soares, Nilofer S. Azad, Nita Ahuja, Christopher J. Gamper, Alex B. Blair, Stephen Muth, Ding Ding, Brian H. Ladle, Lei Zheng
Doxorubicin (DOX), a chemotherapeutic agent, induces a cardiotoxicity referred to as doxorubicin-induced cardiomyopathy (DIC). This cardiotoxicity often limits chemotherapy for malignancies and is associated with poor prognosis. However, the molecular mechanism underlying this cardiotoxicity is yet to be fully elucidated. Here, we show that DOX downregulated glutathione peroxidase 4 (GPx4) and induced excessive lipid peroxidation through DOX-Fe2+ complex in mitochondria, leading to mitochondria-dependent ferroptosis; we also show that mitochondria-dependent ferroptosis is a major cause of DOX cardiotoxicity. In DIC mice, the left ventricular ejection fraction was significantly impaired, and fibrosis and TUNEL+ cells were induced at day 14. Additionally, GPx4, an endogenous regulator of ferroptosis, was downregulated, accompanied by the accumulation of lipid peroxides, especially in mitochondria. These cardiac impairments were ameliorated in GPx4 Tg mice and exacerbated in GPx4 heterodeletion mice. In cultured cardiomyocytes, GPx4 overexpression or iron chelation targeting Fe2+ in mitochondria prevented DOX-induced ferroptosis, demonstrating that DOX triggered ferroptosis in mitochondria. Furthermore, concomitant inhibition of ferroptosis and apoptosis with ferrostatin-1 and zVAD-FMK fully prevented DOX-induced cardiomyocyte death. Our findings suggest that mitochondria-dependent ferroptosis plays a key role in progression of DIC and that ferroptosis is the major form of regulated cell death in DOX cardiotoxicity.
Tomonori Tadokoro, Masataka Ikeda, Tomomi Ide, Hiroko Deguchi, Soichiro Ikeda, Kosuke Okabe, Akihito Ishikita, Shouji Matsushima, Tomoko Koumura, Ken-ichi Yamada, Hirotaka Imai, Hiroyuki Tsutsui
No posts were found with this tag.