Acute pancreatitis (AP), a human disease in which the pancreas digests itself, has substantial mortality with no specific therapy. The major causes of AP are alcohol abuse and gallstone complications, but it also occurs as an important side effect of the standard Asparaginase-based therapy for childhood acute lymphoblastic leukaemia. Previous investigations into the mechanisms underlying pancreatic acinar cell death induced by alcohol metabolites, bile acids or Asparaginase indicated that loss of intracellular ATP generation is a significant factor. In isolated mouse pancreatic acinar cells or cell clusters, we now report that removal of extracellular glucose had little effect on this ATP loss, suggesting that glucose metabolism was severely inhibited under these conditions. Surprisingly, we show that replacing glucose with galactose prevented or markedly reduced the loss of ATP and any subsequent necrosis. Addition of pyruvate had a similar protective effect. We also studied the effect of galactose in vivo in mouse models of AP induced either by a combination of fatty acids and ethanol or Asparaginase. In both cases, galactose markedly reduced acinar necrosis and inflammation. Based on these data we suggest that galactose feeding may be used to protect against AP.
Shuang Peng, Julia V. Gerasimenko, Tetyana M. Tsugorka, Oleksiy Gryshchenko, Sujith Samarasinghe, Ole H. Petersen, Oleg V. Gerasimenko
Painful signals are transmitted by mutisynaptic glutamatergic pathways. Their first synapse between primary nociceptors and excitatory spinal interneurons gates sensory load. Glutamate release herein is orchestrated by Ca2+ sensor proteins with neuronal calcium-binding protein 2 (NECAB2) being particularly abundant. However, neither the importance of NECAB2+ neuronal contingents in dorsal root ganglia (DRG) and spinal cord nor function-determination by NECAB2 has been defined. A combination of histochemistry and single-cell RNA-seq showed NECAB2 in small/medium-sized C- and Aδ D-hair low threshold mechanoreceptors in DRG, as well as in protein kinase γ-positive excitatory spinal interneurons. NECAB2 was downregulated by peripheral nerve injury, offering the hypothesis that NECAB2 loss-of-funtion could limit pain sensation. Indeed, Necab2–/– mice reached a pain-free state significantly faster after peripheral inflammation than wild-type littermates. Genetic access to transiently-activated neurons revealed that a mediodorsal cohort of NECAB2+ neurons mediates inflammatory pain in mouse spinal dorsal horn. Here, besides dampening excitatory transmission in spinal interneurons, NECAB2 limited pronociceptive brain-derived neurotrophic factor release from sensory afferents. Hox8b-dependent reinstatement of NECAB2 expression in Necab2–/– mice then demonstrated that spinal/DRG NECAB2 alone could control inflammation-induced sensory hyperensitivity. Overall, we identify NECAB2 as a critical component of pro-nociceptive pain signaling whose inactivation offers substantial pain relief.
Ming-Dong Zhang, Jie Su, Csaba Adori, Valentina Cinquina, Katarzyna Malenczyk, Fatima Girach, Changgeng Peng, Patrik Ernfors, Peter Löw, Lotta Borgius, Ole Kiehn, Masahiko Watanabe, Mathias Uhlén, Nicholas Mitsios, Jan Mulder, Tibor Harkany, Tomas Hökfelt
T cells must migrate in order to encounter antigen-presenting cells (APCs) and to execute their varied functions in immune defense and inflammation. ATP release and autocrine signaling through purinergic receptors contribute to T cell activation at the immune synapse that T cells form with APCs. Here, we show that T cells also require ATP release and purinergic signaling for their migration to APCs. We found that the chemokine SDF-1α triggered mitochondrial ATP production, rapid bursts of ATP release, and increased migration of primary human CD4+ T cells. This process depended on pannexin-1 ATP release channels and autocrine stimulation of P2X4 receptors. SDF-1α stimulation caused localized accumulation of mitochondria with P2X4 receptors near the front of cells, resulting in a feed-forward signaling mechanism that promotes cellular Ca2+ influx and sustains mitochondrial ATP synthesis at levels needed for pseudopod protrusion, T cell polarization, and cell migration. Inhibition of P2X4 receptors blocked the activation and migration of T cells in vitro. In a mouse lung transplant model, P2X4 receptor antagonist treatment prevented the recruitment of T cells into allograft tissue and the rejection of lung transplants. Our findings suggest that P2X4 receptors are therapeutic targets for immunomodulation in transplantation and inflammatory diseases.
Carola Ledderose, Kaifeng Liu, Yutaka Kondo, Christian J. Slubowski, Thomas Dertnig, Sara Denicoló, Mona Arbab, Johannes Hubner, Kirstin Konrad, Mahtab Fakhari, James A. Lederer, Simon C. Robson, Gary A. Visner, Wolfgang G. Junger
PRDM16 is a transcriptional co-regulator involved in translocations in acute myeloblastic leukemia (AML), myelodysplastic syndromes and T acute lymphoblastic leukemia that is highly expressed in and required for the maintenance of hematopoietic stem cells (HSCs), and can be aberrantly expressed in AML. Prdm16 is expressed as full-length (fPrdm16) and short (sPrdm16) isoforms, the latter lacking the N-terminal PR-domain. The role of both isoforms in normal and malignant hematopoiesis is unclear. We show here that fPrdm16 was critical for HSC maintenance, induced multiple genes involved in GTPase signaling and repressed inflammation, while sPrdm16 supported B-cell development biased towards marginal zone B-cells and induced an inflammatory signature. In a mouse model of human MLL-AF9 leukemia fPrdm16 extended latency, while sPrdm16 shortened latency and induced a strong inflammatory signature, including several cytokines and chemokines that are associated with myelodysplasia and with a worse prognosis in human AML. Finally, in human NPM1-mutant and in MLL-translocated AML high expression of PRDM16, which negatively impacts outcome, was associated with inflammatory gene expression, thus corroborating the mouse data. Our observations demonstrate distinct roles for Prdm16 isoforms in normal HSCs and AML, and identify sPrdm16 as one of the drivers of prognostically adverse inflammation in leukemia.
David J. Corrigan, Larry L. Luchsinger, Mariana Justino de Almeida, Linda J. Williams, Alexandros Strikoudis, Hans-Willem Snoeck
While the genomic binding of MYC protein correlates with active epigenetic marks on chromatin, it remains largely unclear how major epigenetic mechanisms functionally impact the tumorigenic potential of MYC. Here we showed that compared to the catalytic subunits, the core subunits, including DPY30, of the major H3K4 methyltransferase complexes were frequently amplified in human cancers, and selectively upregulated in Burkitt lymphoma. We showed that DPY30 promoted expression of endogenous MYC, and was also functionally important for efficient binding of MYC to its genomic targets by regulating chromatin accessibility. Dpy30 heterozygosity did not affect normal animal physiology including life span, but significantly suppressed Myc-driven lymphomagenesis, as cells failed to combat oncogene-triggered apoptosis due to insufficient epigenetic modulation and expression of a subset of anti-apoptotic genes. Dpy30 reduction also greatly impeded MYC-dependent cellular transformation without affecting normal cell growth. These results suggest that MYC hijacks a major epigenetic pathway — H3K4 methylation — to facilitate its molecular activity in target binding and to coordinate its oncogenic program for efficient tumorigenesis, meanwhile creating “epigenetic vulnerability.” DPY30 and the H3K4 methylation pathway are thus potential epigenetic targets for treating certain MYC-driven cancers.
Zhenhua Yang, Kushani Shah, Theodore Busby, Keith Giles, Alireza Khodadadi-Jamayran, Wei Li, Hao Jiang
Neuronatin (Nnat) is an imprinted gene implicated in human obesity and widely expressed in neuroendocrine and metabolic tissues in a hormone and nutrient-sensitive manner. However, its molecular and cellular functions and precise role in organismal physiology remain only partly defined. Here we demonstrate that mice lacking Nnat globally or specifically in β cells display impaired glucose-stimulated insulin secretion leading to defective glucose handling under conditions of nutrient-excess. In contrast, we report no evidence for any feeding or body weight phenotypes in global Nnat null mice. At the molecular level neuronatin augments insulin signal peptide cleavage by binding to the signal peptidase complex and facilitates translocation of the nascent preprohormone. Loss of neuronatin expression in β cells therefore reduces insulin content and blunts glucose-stimulated insulin secretion. Nnat expression, in turn, is glucose-regulated. This mechanism therefore represents a novel site of nutrient-sensitive control of β cell function and whole animal glucose homeostasis. These data also suggest a potential wider role for Nnat in the regulation of metabolism through the modulation of peptide processing events.
Steven J. Millership, Gabriela da Silva Xavier, Agharul I. Choudhury, Sergio Bertazzo, Pauline Chabosseau, Silvia M.A. Pedroni, Elaine E. Irvine, Alex Montoya, Peter Faull, William R. Taylor, Julie Kerr-Conte, Francois Pattou, Jorge Ferrer, Mark Christian, Rosalind M. John, Mathieu Latreille, Ming Liu, Guy A. Rutter, James Scott, Dominic J. Withers
In type 1 diabetes, cytotoxic CD8 T cells with specificity for β-cell autoantigens are found in the pancreatic islets where they are implicated in the destruction of insulin-secreting β cells. In contrast, the disease relevance of β-cell-reactive CD8 T cells that are detectable in the circulation, and their relationship to β-cell function, are not known. Here, we tracked multiple, circulating β-cell-reactive CD8 T cell subsets and measured β-cell function longitudinally for two years, starting immediately after diagnosis of type 1 diabetes. We found that change in β-cell-specific effector memory CD8 T cells expressing CD57 was positively correlated with C-peptide change in subjects below 12 years of age. Autoreactive CD57+ effector memory CD8 T cells bore the signature of enhanced effector function (higher expression of granzyme B, killer specific protein 37 and CD16, and reduced expression of CD28) compared with their CD57-negative counterparts, and network association modelling indicated that the dynamics of β-cell-reactive CD57+ effector memory CD8 T cell subsets were strongly linked. Thus, coordinated changes in circulating β-cell-specific CD8 T cells within the CD57+ effector memory subset calibrate to functional insulin reserve in type 1 diabetes, providing a tool for immune monitoring and a mechanism-based target for immunotherapy.
Lorraine Yeo, Alyssa Woodwyk, Sanjana Sood, Anna Lorenc, Martin Eichmann, Irma Pujol-Autonell, Rossella Melchiotti, Ania Skowera, Efthymios Fidanis, Garry M. Dolton, Katie Tungatt, Andrew K. Sewell, Susanne Heck, Alka Saxena, Craig A. Beam, Mark Peakman
Skeletal muscle has emerged as a critical, disease-relevant target tissue in spinal and bulbar muscular atrophy, a degenerative disorder of the neuromuscular system caused by a CAG/polyglutamine (polyQ) expansion in the androgen receptor (AR) gene. Here, we used RNA-Seq to identify pathways that are disrupted in diseased muscle using AR113Q knock-in mice. This analysis unexpectedly identified significantly diminished expression of numerous ubiquitin-proteasome pathway genes in AR113Q muscle, encoding approximately 30% of proteasome subunits and 20% of E2 ubiquitin conjugases. These changes were age-, hormone- and glutamine length-dependent and arose due to a toxic gain-of-function conferred by the mutation. Moreover, altered gene expression was associated with decreased level of the proteasome transcription factor NRF1 and its activator DDI2 and resulted in diminished proteasome activity. Ubiquitinated ADRM1 was detected in AR113Q muscle, indicating the occurrence of stalled proteasomes in mutant mice. Finally, diminished expression of Drosophila orthologues of NRF1 or ADRM1 promoted the accumulation of polyQ AR protein and increased toxicity. Collectively, these data indicate that AR113Q muscle develops progressive proteasome dysfunction that leads to the impairment of quality control and the accumulation of polyQ AR protein, key features that contribute to the age-dependent onset and progression of this disorder.
Samir R. Nath, Zhigang Yu, Theresa A. Gipson, Gregory B. Marsh, Eriko Yoshidome, Diane M. Robins, Sokol V. Todi, David E. Housman, Andrew P. Lieberman
The tumor-suppressive role of trefoil factor family (TFF) members has been suggested in gastric carcinogenesis, but their significance and mechanisms in other digestive diseases remain elusive. To clarify the role of TFF1 in pancreatic carcinogenesis, we performed immunohistochemistry on human samples, transfected siRNA against TFF1 into pancreatic cancer cell lines, and employed mouse models in which PanIN development and loss of TFF1 occurs simultaneously. In human samples, the expression of TFF1 was specifically observed in pancreatic intraepithelial neoplasm (PanIN) but was frequently lost in the invasive component of pancreatic ductal adenocarcinoma (PDAC). When the expression of TFF1 was suppressed in vitro, pancreatic cancer cell lines showed enhanced invasive ability and features of epithelial-mesenchymal transition (EMT), including upregulated Snail expression. TFF1 expression was also observed in PanIN lesions of Pdx-1 Cre; LSL-KRASG12D (KC) mice, a model of pancreatic cancer, and loss of TFF1 in these mice resulted in the expansion of PanIN lesions, an EMT phenotype in PanIN cells, and an accumulation of cancer-associated fibroblasts (CAFs), eventually resulting in the development of invasive adenocarcinoma. This study indicates that the acquisition of TFF1 expression is an early event in pancreatic carcinogenesis and that TFF1 might act as a tumor suppressor to prevent EMT and the invasive transformation of PanIN.
Junpei Yamaguchi, Yukihiro Yokoyama, Toshio Kokuryo, Tomoki Ebata, Atsushi Enomoto, Masato Nagino
Enterotoxigenic Escherichia coli (ETEC) infections are highly prevalent in developing countries where clinical presentations range from asymptomatic colonization to severe cholera-like illness. The molecular basis for these varied presentations, that may involve strain-specific virulence features as well as host factors, have not been elucidated. We demonstrate that when challenged with ETEC strain H10407, originally isolated from a case of cholera-like illness, blood group A human volunteers developed severe diarrhea more frequently than individuals from other blood groups. Interestingly, a diverse population of ETEC strains, including H10407, secrete a novel adhesin molecule, EtpA. As many bacterial adhesins also agglutinate red blood cells, we combined the use of glycan arrays, biolayer inferometry, and non-canonical amino acid labeling with hemagglutination studies to demonstrate that EtpA is a dominant ETEC blood group A specific lectin/hemagglutinin. Importantly, we also show that EtpA interacts specifically with glycans expressed on intestinal epithelial cells from blood group A individuals, and that EtpA-mediated bacterial-host interactions accelerate bacterial adhesion and the effective delivery both heat-labile and heat-stable toxins of ETEC. Collectively, these data provide additional insight into the complex molecular basis of severe ETEC diarrheal illness that may inform rational design of vaccines to protect those at highest risk.
Pardeep Kumar, F. Matthew Kuhlmann, Subhra Chakroborty, A. Louis Bourgeois, Jennifer Foulke-Abel, Brunda Tumala, Tim J. Vickers, David A. Sack, Barbara DeNearing, Clayton D. Harro, W. Shea Wright, Jeffrey C. Gildersleeve, Matthew A. Ciorba, Srikanth Santhanam, Chad K. Porter, Ramiro L. Gutierrez, Michael G. Prouty, Mark S. Riddle, Alexander Polino, Alaullah Sheikh, Mark Donowitz, James M. Fleckenstein
No posts were found with this tag.