Hereditary angioedema (HAE) is an autosomal dominant disease characterized by recurrent edema attacks associated with morbidity and mortality. HAE results from variations in the SERPING1 gene encoding C1 inhibitor (C1INH), a serine protease inhibitor (serpin). Reduced plasma levels of C1INH lead to enhanced activation of the contact system triggering high levels of bradykinin and increased vascular permeability, but the cellular mechanisms leading to low C1INH levels (20-30% of normal) in heterozygous HAE type I patients remain obscure. Here, we showed that C1INH encoded by a subset of HAE-causing SERPING1 alleles affected secretion of normal C1INH protein in a dominant negative fashion by triggering formation of protein-protein interactions between normal and mutant C1INH leading to creation of larger intracellular C1INH aggregates that were trapped in the endoplasmic reticulum (ER). Notably, intracellular aggregation of C1INH and ER abnormality were observed in fibroblasts from a heterozygous carrier of a dominant negative SERPING1 gene variant, but the condition was ameliorated by viral delivery of the SERPING1 gene. Collectively, our data link abnormal accumulation of serpins, a hallmark of serpinopathies, with dominant negative disease mechanisms affecting C1INH plasma levels in HAE type I patients and may pave the way for new treatments of HAE.
Didde Haslund, Laura Barrett Ryø, Sara Seidelin Majidi, Iben Kløvgaard Rose, Kristian Alsbjerg Skipper, Tue Fryland, Anja Bille Bohn, Claus Koch, Martin K. Thomsen, Yaseelan Palarasah, Thomas J. Corydon, Anette Bygum, Lene N. Nejsum, Jacob Giehm Mikkelsen
The negatively charged sugar sialic acid (Sia) occupies the outermost position in the bulk of cell surface glycans. Lack of sialylated glycans due to genetic ablation of the Sia activating enzyme CMP-sialic acid synthase (CMAS) resulted in embryonic lethality around day 9.5 post coitum (E9.5) in mice. Developmental failure was caused by complement activation on trophoblasts in Cmas-/- implants accompanied by infiltration of maternal neutrophils at the fetal-maternal interface, intrauterine growth restriction, impaired placental development and a thickened Reichert’s membrane. This phenotype, which shared features with complement-recepter-1 related protein Y (Crry) depletion, was rescued in E8.5 Cmas-/- mice upon injection of cobra venom factor resulting in exhaustion of the maternal complement component C3. Here we show that Sia is dispensable for early development of the embryo proper, but pivotal for fetal-maternal immune homeostasis during pregnancy, i.e. for protecting the allograft implant against attack by the maternal innate immune system. Finally, embryos devoid of cell surface sialylation suffered from malnutrition due to inadequate placentation as secondary effect.
Markus Abeln, Iris Albers, Ulrike Peters-Bernard, Kerstin Flächsig-Schulz, Elina Kats, Andreas Kispert, Stephen Tomlinson, Rita Gerardy-Schahn, Anja Münster-Kühnel, Birgit Weinhold
BACKGROUND. Chronic Obstructive Pulmonary Disease (COPD) is a heterogeneous smoking-related disease characterized by airway obstruction and inflammation. This inflammation may persist even after smoking cessation and responds variably to corticosteroids. Personalizing treatment to biologically similar “molecular phenotypes” may improve therapeutic efficacy in COPD. IL-17A is involved in neutrophilic inflammation and corticosteroid resistance, and thus may be particularly important in a COPD molecular phenotype. METHODS. We generated a gene expression signature of IL-17A response in bronchial airway epithelial brushings (“BAE”) from smokers with and without COPD (n = 238), and validated it using data from two randomized trials of IL-17 blockade in psoriasis. This IL-17 signature was related to clinical and pathologic characteristics in two additional human studies of COPD: (1) SPIROMICS (n = 47), which included former and current smokers with COPD, and (2) GLUCOLD (n = 79), in which COPD participants were randomized to placebo or corticosteroids. RESULTS. The IL-17 signature was associated with an inflammatory profile characteristic of an IL-17 response, including increased airway neutrophils and macrophages. In SPIROMICS the signature was associated with increased airway obstruction and functional small airway disease on quantitative chest CT. In GLUCOLD the signature was associated with decreased response to corticosteroids, irrespective of airway eosinophilic or Type 2 inflammation. CONCLUSION. These data suggest that a gene signature of IL-17 airway epithelial response distinguishes a biologically, radiographically, and clinically distinct COPD subgroup that may benefit from personalized therapy. TRIAL REGISTRATION. ClinicalTrials.gov NCT01969344. FUNDING. Primary support from NIH/NHLBI. For others see below.
Stephanie A. Christenson, Maarten van den Berge, Alen Faiz, Kai Imkamp, Nirav Bhakta, Luke R. Bonser, Lorna T. Zlock, Igor Z. Barjaktarevic, R. Graham Barr, Eugene R. Bleecker, Richard C. Boucher, Russell P. Bowler, Alejandro P. Comellas, Jeffrey L. Curtis, MeiLan K. Han, Nadia N. Hansel, Pieter S. Hiemstra, Robert J. Kaner, Jerry A. Krishnan, Fernando J. Martinez, Wanda K. O'Neal, Robert Paine III, Wim Timens, J. Michael Wells, Avrum Spira, David J. Erle, Prescott G. Woodruff
Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme detoxifying acetaldehyde and endogenous lipid aldehydes; previous studies suggest a protective role of ALDH2 against cardiovascular disease (CVD). Around 40% of East Asians carrying a single nucleotide polymorphism (SNP) ALDH2 rs671 have increased incidences of CVD. However, the role of ALDH2 in CVD beyond alcohol consumption remains poorly defined. Here we report that ALDH2/LDLR DKO mice have decreased atherosclerosis compared to LDLR KO mice, whereas ALDH2/APOpoE DKO have increased atherosclerosis, suggesting an unexpected interaction of ALDH2 with LDLR. Further studies demonstrate that in the absence of LDLR, AMPK phosphorylates ALDH2 at threonine 356 and enables its nuclear translocation. Nuclear ALDH2 interacts with HDAC3 and represses transcription of a lysosomal proton pump protein ATP6Vv0Ee2, critical for maintaining lysosomal function, autophagy and degradation of oxLDL. Interestingly, an interaction of cytosolic LDLR C-terminus with AMPK blocks ALDH2 phosphorylation and subsequent nuclear translocation, whereas ALDH2 rs671 mutant in human macrophages attenuates this interaction, which releases ALDH2 to nucleus to suppress ATP6Vv0Ee2 expression, resulting in increased foam cells due to impaired lysosomal function. Our studies reveal a novel role of ALDH2 and LDLR in atherosclerosis and provide a molecular mechanism by which ALDH2 rs671 SNP increases CVD.
Shanshan Zhong, Luxiao Li, Yu-Lei Zhang, Lili Zhang, Jianhong Lu, Shuyuan Guo, Ningning Liang, Jing Ge, Mingjiang Zhu, Yongzhen Tao, Yun-Cheng Wu, Huiyong Yin
Notch signaling regulates differentiation of the pancreatic endocrine lineage during embryogenesis, but the role of Notch in mature β cells is unclear. We found that islets derived from lean mice show modest β cell Notch activity, which increases in obesity and in response to high glucose. This response appeared maladaptive, as mice with β cell-specific deficient Notch transcriptional activity (β-Rbpj, β-DNMAML) showed improved glucose tolerance when subjected to high-fat diet feeding. Conversely, mice with β cell-specific expression of constitutively-active Notch1 (β-NICD) had a progressive loss of β cell maturity, due to proteasomal degradation of MafA, leading to impaired glucose-stimulated insulin secretion and glucose intolerance with aging or obesity. Surprisingly, Notch-active β cells had increased proliferative capacity, leading to increased but dysfunctional β cell mass. These studies demonstrate a dynamic role for Notch in developed β cells to simultaneously regulate β cell function and proliferation.
Alberto Bartolome, Changyu Zhu, Lori Sussel, Utpal B. Pajvani
Replicative immortality is a hallmark of cancer governed by telomere maintenance. About 90% of human cancers maintain their telomeres by activating telomerase, driven by transcriptional upregulation of telomerase reverse transcriptase (TERT). Although TERT promoter mutations (TPMs) are a major cancer-associated genetic mechanism of TERT upregulation, many cancers exhibit TERT upregulation without TPMs. In this study, we described TERT Hypermethylated Oncological Region (THOR), a 433-bp genomic region encompassing 52 CpG sites located immediately upstream of the TERT core promoter, as a cancer-associated epigenetic mechanism of TERT upregulation. Unmethylated THOR repressed TERT promoter activity regardless of TPMs status, and hypermethylation of THOR counteracted this repressive function. THOR methylation analysis in 1,352 human tumors revealed frequent (>45%) cancer-associated DNA hypermethylation in 9 of 11 (82%) tumor types screened. Additionally, THOR hypermethylation — either independently or along with TPMs — accounted for how approximately 90% of human cancers can aberrantly activate telomerase. Thus, we propose THOR hypermethylation as a prevalent telomerase activating mechanism in cancer that can act independently or in conjunction with TPMs, further supporting the utility of THOR hypermethylation as a prognostic biomarker.
Donghyun D. Lee, Ricardo Leão, Martin Komosa, Marco Gallo, Cindy H. Zhang, Tatiana Lipman, Marc Remke, Abolfazl Heidari, Nuno Miguel Nunes, Joana D. Apolónio, Ramon Andrade De Mello, João Dias, David Huntsman, Thomas Hermanns, Peter J. Wild, Robert Vanner, Gelareh Zadeh, Jason Karamchandani, Sunit Das, Michael D. Taylor, Cynthia E. Hawkins, Jonathan D. Wasserman, Arnaldo Figueiredo, Robert J. Hamilton, Mark D. Minden, Khalida Wani, Bill Diplas, Hai Yan, Kenneth Aldape, Mohammad R. Akbari, Arnavaz Danesh, Trevor J. Pugh, Peter B. Dirks, Pedro Castelo-Branco, Uri Tabori
Levothyroxine (LT4) is a form of thyroid hormone used to treat hypothyroidism. In the brain, T4 is converted to the active form T3 by the type 2 deiodinase (D2). Thus, it is intriguing that carriers of the Thr92Ala polymorphism in the D2 gene (DIO2) exhibit clinical improvement when liothyronine (LT3) is added to LT4 therapy. Here we report that D2 is a cargo protein in endoplasmic reticulum Golgi intermediary compartment (ERGIC) vesicles, recycling between ER and Golgi. The Thr92 to Ala substitution (Ala92-D2) caused ER stress and activated the unfolded protein response (UPR); Ala92-D2 accumulated in the trans-Golgi and generated less T3, all of which was restored by eliminating ER stress with the chemical chaperone 4-phenyl butyric acid (4-PBA). An Ala92-Dio2 polymorphism-carrying mouse exhibited UPR and hypothyroidism in distinct brain areas. The mouse refrained from physical activity, slept more and required additional time to memorize objects. Enhancing T3 signaling in the brain with LT3 improved cognition, whereas restoring proteostasis with 4-PBA eliminated the Ala92-Dio2 phenotype. In contrast, primary hypothyroidism intensified the Ala92-Dio2 phenotype, with only partial response to LT4 therapy. Disruption of cellular proteostasis and reduced Ala92-D2 activity may explain the failure of LT4 therapy in carriers of Thr92Ala-DIO2.
Sungro Jo, Tatiana L. Fonseca, Barbara M.L. Da Costa Bocco, Gustavo W. Fernandes, Elizabeth A. McAninch, Anaysa P. Bolin, Rodrigo R. Da Conceição, Joao Pedro W.S. De Castro, Daniele L. Ignacio, Péter Egri, Dorottya Németh, Csaba Fekete, Maria Martha Bernardi, Victoria D. Leitch, Naila S. Mannan, Katharine F. Curry, Natalie C. Butterfield, J.H. Duncan Bassett, Graham R. Williams, Balázs Gereben, Miriam O. Ribeiro, Antonio C. Bianco
Angelman syndrome (AS) is a neurodevelopmental disorder in which epilepsy is common (~90%) and often refractory to antiepileptics. AS is caused by mutation of the maternal allele encoding the ubiquitin protein ligase E3A (UBE3A), but it is unclear how this genetic insult confers vulnerability to seizure development and progression (i.e., epileptogenesis). Here we implemented the flurothyl kindling and retest paradigm in AS model mice to assess epileptogenesis and to gain mechanistic insights owed to loss of maternal Ube3a. AS model mice kindled similarly to wildtype mice, but they displayed a markedly increased sensitivity to flurothyl-, kainic acid-, and hyperthermia-induced seizures measured a month later during retest. Pathological characterization revealed enhanced deposition of perineuronal nets in dentate gyrus of hippocampus of AS mice in the absence of overt neuronal loss or mossy fiber sprouting. This pro-epileptogenic phenotype resulted from Ube3a deletion in GABAergic but not glutamatergic neurons, and it was rescued by pancellular reinstatement of Ube3a at postnatal day 21 (P21), but not during adulthood. Our results suggest that epileptogenic susceptibility in AS patients is a consequence of the dysfunctional development of GABAergic circuits, which may be amenable to therapies leveraging juvenile reinstatement of UBE3A.
Bin Gu, Kelly E. Carstens, Matthew C. Judson, Katherine A. Dalton, Marie Rougié, Ellen P. Clark, Serena M. Dudek, Benjamin D. Philpot
Iron-related disorders are among the most prevalent diseases worldwide. Systemic iron homeostasis requires hepcidin, a hepatic-derived hormone that controls iron mobilization through its molecular target, ferroportin (FPN), the only known mammalian iron exporter. This pathway is perturbed in diseases that cause iron overload. Additionally, intestinal HIF-2α is essential for the local absorptive response to systemic iron deficiency and iron overload. Our data demonstrate a hetero-tissue crosstalk mechanism, where liver hepcidin regulated intestinal HIF-2α in iron deficiency, anemia, and iron overload. We show that FPN controlled cell autonomous iron efflux to regulate the activity of iron-dependent, intestinal prolyl hydroxylase domain enzymes to stabilize HIF-2α. Pharmacological blockade of HIF-2α using a clinically relevant and highly specific inhibitor successfully treated iron overload in a mouse model. These findings demonstrate a molecular link between liver hepcidin and intestinal HIF-2α that controls physiological iron uptake and drives iron hyperabsorption during iron overload.
Andrew J. Schwartz, Nupur K. Das, Sadeesh K. Ramakrishnan, Chesta Jain, Mladen Jurkovic, Jun Wu, Elizabeta Nemeth, Samira Lakhal-Littleton, Justin A. Colacino, Yatrik M. Shah
The loss of insulin-secreting β cells is characteristic among Type I and Type II diabetes. Stimulating proliferation to expand sources of β cells for transplantation remains a challenge because adult β cells do not proliferate readily. The cell cycle inhibitor p57 has been shown to control cell division in human β cells. Expression of p57 is regulated by the DNA methylation status of the Imprinting Control Region 2 (ICR2), which is commonly hypomethylated in Beckwith Wiedemann-Syndrome patients who exhibit massive β cell proliferation. We hypothesized that targeted demethylation of the ICR2 using a transcription activator-like effector protein fused to the catalytic domain of TET1 (ICR2-TET1) would repress p57 expression and promote cell proliferation. We report here that overexpression of ICR2-TET1 in human fibroblasts reduces p57 expression levels and increases proliferation. Furthermore, human islets overexpressing ICR2-TET1 exhibit repression of p57 with concomitant upregulation of Ki-67 while maintaining glucose-sensing functionality. When transplanted into diabetic, immunodeficient mice, the epigenetically edited islets show increased β cell replication compared to control islets. These findings demonstrate that epigenetic editing is a promising tool for inducing β cell proliferation, which may one day alleviate the scarcity of transplantable β cells for the treatment of diabetes.
Kristy Ou, Ming Yu, Nicholas G. Moss, Yue J. Wang, Amber W. Wang, Son C. Nguyen, Connie Jiang, Eseye Feleke, Vasumathi Kameswaran, Eric F. Joyce, Ali Naji, Benjamin Glaser, Dana Avrahami, Klaus H. Kaestner
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