Replicative immortality is a hallmark of cancer cells governed by telomere maintenance. Approximately 90% of human cancers maintain their telomeres by activating telomerase, driven by the 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 describe the 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 TPM 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 that THOR hypermethylation is a prevalent telomerase-activating mechanism in cancer that can act independently of 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, Aryeh J. Price, Ramon Andrade De Mello, João S. 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
Acetaldehyde 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 the single nucleotide polymorphism (SNP) ALDH2 rs671 have an increased incidence of CVD. However, the role of ALDH2 in CVD beyond alcohol consumption remains poorly defined. Here we report that ALDH2/LDLR double knockout (DKO) mice have decreased atherosclerosis compared with LDLR-KO mice, whereas ALDH2/APOE-DKO mice 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 ATP6V0E2, critical for maintaining lysosomal function, autophagy, and degradation of oxidized low-density lipid protein. 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 the nucleus to suppress ATP6V0E2 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
Levothyroxine (LT4) is a form of thyroid hormone used to treat hypothyroidism. In the brain, T4 is converted to the active form T3 by 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 ER 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, 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. C. Bocco, Gustavo W. Fernandes, Elizabeth A. McAninch, Anaysa P. Bolin, Rodrigo R. Da Conceição, Joao Pedro Werneck-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
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 showed improved glucose tolerance when subjected to high-fat diet feeding. Conversely, mice with β cell–specific Notch gain of function (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 for simultaneously regulating β cell function and proliferation.
Alberto Bartolome, Changyu Zhu, Lori Sussel, Utpal B. Pajvani
In response to viral pathogens, the host upregulates antiviral genes that suppress translation of viral mRNAs. However, induction of such antiviral responses may not be exclusive to viruses, as the pathways lie at the intersection of broad inflammatory networks that can also be induced by bacterial pathogens. Using a model of Gram-negative sepsis, we show that propagation of kidney damage initiated by a bacterial origin ultimately involves antiviral responses that result in host translation shutdown. We determined that activation of the eukaryotic translation initiation factor 2-α kinase 2/eukaryotic translation initiation factor 2α (Eif2ak2/Eif2α) axis is the key mediator of translation initiation block in late-phase sepsis. Reversal of this axis mitigated kidney injury. Furthermore, temporal profiling of the kidney translatome revealed that multiple genes involved in formation of the initiation complex were translationally altered during bacterial sepsis. Collectively, our findings imply that translation shutdown is indifferent to the specific initiating pathogen and is an important determinant of tissue injury in sepsis.
Takashi Hato, Bernhard Maier, Farooq Syed, Jered Myslinski, Amy Zollman, Zoya Plotkin, Michael T. Eadon, Pierre C. Dagher
The lipin phosphatidic acid phosphatase (PAP) enzymes are required for triacylglycerol (TAG) synthesis from glycerol 3-phosphate in most mammalian tissues. The 3 lipin proteins (lipin 1, lipin 2, and lipin 3) each have PAP activity, but have distinct tissue distributions, with lipin 1 being the predominant PAP enzyme in many metabolic tissues. One exception is the small intestine, which is unique in expressing exclusively lipin 2 and lipin 3. TAG synthesis in small intestinal enterocytes utilizes 2-monoacylglycerol and does not require the PAP reaction, making the role of lipin proteins in enterocytes unclear. Enterocyte TAGs are stored transiently as cytosolic lipid droplets or incorporated into lipoproteins (chylomicrons) for secretion. We determined that lipin enzymes are critical for chylomicron biogenesis, through regulation of membrane phospholipid composition and association of apolipoprotein B48 with nascent chylomicron particles. Lipin 2/3 deficiency caused phosphatidic acid accumulation and mammalian target of rapamycin complex 1 (mTORC1) activation, which were associated with enhanced protein levels of a key phospholipid biosynthetic enzyme (CTP:phosphocholine cytidylyltransferase α) and altered membrane phospholipid composition. Impaired chylomicron synthesis in lipin 2/3 deficiency could be rescued by normalizing phospholipid synthesis levels. These data implicate lipin 2/3 as a control point for enterocyte phospholipid homeostasis and chylomicron biogenesis.
Peixiang Zhang, Lauren S. Csaki, Emilio Ronquillo, Lynn J. Baufeld, Jason Y. Lin, Alexis Gutierrez, Jennifer R. Dwyer, David N. Brindley, Loren G. Fong, Peter Tontonoz, Stephen G. Young, Karen Reue
Using an integrated approach to characterize the pancreatic tissue and isolated islets from a 33-year-old with 17 years of type 1 diabetes (T1D), we found that donor islets contained β cells without insulitis and lacked glucose-stimulated insulin secretion despite a normal insulin response to cAMP-evoked stimulation. With these unexpected findings for T1D, we sequenced the donor DNA and found a pathogenic heterozygous variant in the gene encoding hepatocyte nuclear factor-1α (HNF1A). In one of the first studies of human pancreatic islets with a disease-causing HNF1A variant associated with the most common form of monogenic diabetes, we found that HNF1A dysfunction leads to insulin-insufficient diabetes reminiscent of T1D by impacting the regulatory processes critical for glucose-stimulated insulin secretion and suggest a rationale for a therapeutic alternative to current treatment.
Rachana Haliyur, Xin Tong, May Sanyoura, Shristi Shrestha, Jill Lindner, Diane C. Saunders, Radhika Aramandla, Greg Poffenberger, Sambra D. Redick, Rita Bottino, Nripesh Prasad, Shawn E. Levy, Raymond D. Blind, David M. Harlan, Louis H. Philipson, Roland W. Stein, Marcela Brissova, Alvin C. Powers
We investigated how pathological changes in newborn hippocampal dentate granule cells (DGCs) lead to epilepsy. Using a rabies virus–mediated retrograde tracing system and a designer receptors exclusively activated by designer drugs (DREADD) chemogenetic method, we demonstrated that newborn hippocampal DGCs are required for the formation of epileptic neural circuits and the induction of spontaneous recurrent seizures (SRS). A rabies virus–mediated mapping study revealed that aberrant circuit integration of hippocampal newborn DGCs formed excessive de novo excitatory connections as well as recurrent excitatory loops, allowing the hippocampus to produce, amplify, and propagate excessive recurrent excitatory signals. In epileptic mice, DREADD-mediated–specific suppression of hippocampal newborn DGCs dramatically reduced epileptic spikes and SRS in an inducible and reversible manner. Conversely, specific activation of hippocampal newborn DGCs increased both epileptic spikes and SRS. Our study reveals an essential role for hippocampal newborn DGCs in the formation and function of epileptic neural circuits, providing critical insights into DGCs as a potential therapeutic target for treating epilepsy.
Qi-Gang Zhou, Ashley D. Nemes, Daehoon Lee, Eun Jeoung Ro, Jing Zhang, Amy S. Nowacki, Susan M. Dymecki, Imad M. Najm, Hoonkyo Suh
Recurrent broad-scale heterozygous deletions are frequently observed in human cancer. Here we tested the hypothesis that compound haploinsufficiency of neighboring genes at chromosome 8p promotes tumorigenesis. By targeting the mouse orthologs of human DOK2 and DUSP4 genes, which were co-deleted in approximately half of human lung adenocarcinomas, we found that compound-heterozygous deletion of Dok2 and Dusp4 in mice resulted in lung tumorigenesis with short latency and high incidence, and that their co-deletion synergistically activated MAPK signaling and promoted cell proliferation. Conversely, restoration of DOK2 and DUSP4 in lung cancer cells suppressed MAPK activation and cell proliferation. Importantly, in contrast to downregulation of DOK2 or DUSP4 alone, concomitant downregulation of DOK2 and DUSP4 was associated with poor survival in human lung adenocarcinoma. Therefore, our findings lend in vivo experimental support to the notion that compound haploinsufficiency, due to broad-scale chromosome deletions, constitutes a driving force in tumorigenesis.
Ming Chen, Jiangwen Zhang, Alice H. Berger, Moussa S. Diolombi, Christopher Ng, Jacqueline Fung, Roderick T. Bronson, Mireia Castillo-Martin, Tin Htwe Thin, Carlos Cordon-Cardo, Robin Plevin, Pier Paolo Pandolfi
A considerable body of evidence suggests that Fc-dependent functions improve the capacity of broadly neutralizing antibodies (BnAbs) to protect against and control HIV-1 infection. This phenomenon, however, has not been formally tested in robust cell-associated macaque simian-human immunodeficiency virus (SHIV) models with newer-generation BnAbs. We studied both the WT BnAb PGT121 and a LALA mutant of PGT121 (which has impaired Fc-dependent functions) for their ability to protect pigtail macaques from an i.v. high-dose cell-associated SHIVSF162P3 challenge. We found that both WT and LALA PGT121 completely protected all 12 macaques studied. Further, partial depletion of NK cells, key mediators of Fc-dependent functions, did not abrogate the protective efficacy of PGT121 in 6 macaques. Additionally, in animals with established SHIVSF162P3 infection, SHIV viremia levels were equally rapidly reduced by LALA and WT PGT121. Our studies suggest that the potent neutralizing capacity of PGT121 renders the Fc-dependent functions of the Ab at least partially redundant. These findings have implications for Ab-mediated protection from and control of HIV-1 infection.
Matthew S. Parsons, Wen Shi Lee, Anne B. Kristensen, Thakshila Amarasena, Georges Khoury, Adam K. Wheatley, Arnold Reynaldi, Bruce D. Wines, P. Mark Hogarth, Miles P. Davenport, Stephen J. Kent