Carrying the ε4 allele of the APOE gene encoding apolipoprotein E (APOE4) markedly increases the risk for late-onset Alzheimer’s disease (AD), in which APOE4 exacerbates the brain accumulation and subsequent deposition of amyloid-β (Aβ) peptides. While the LDL receptor–related protein 1 (LRP1) is a major apoE receptor in the brain, we found that its levels are associated with those of insoluble Aβ depending on APOE genotype status in postmortem AD brains. Thus, to determine the functional interaction of apoE4 and LRP1 in brain Aβ metabolism, we crossed neuronal LRP1-knockout mice with amyloid model APP/PS1 mice and APOE3–targeted replacement (APO3-TR) or APOE4-TR mice. Consistent with previous findings, mice expressing apoE4 had increased Aβ deposition and insoluble amounts of Aβ40 and Aβ42 in the hippocampus of APP/PS1 mice compared with those expressing apoE3. Intriguingly, such effects were reversed in the absence of neuronal LRP1. Neuronal LRP1 deficiency also increased detergent-soluble apoE4 levels, which may contribute to the inhibition of Aβ deposition. Together, our results suggest that apoE4 exacerbates Aβ pathology through a mechanism that depends on neuronal LRP1. A better understanding of apoE isoform–specific interaction with their metabolic receptor LRP1 on Aβ metabolism is crucial for defining APOE4-related risk for AD.
Masaya Tachibana, Marie-Louise Holm, Chia-Chen Liu, Mitsuru Shinohara, Tomonori Aikawa, Hiroshi Oue, Yu Yamazaki, Yuka A. Martens, Melissa E. Murray, Patrick M. Sullivan, Kathrin Weyer, Simon Glerup, Dennis W. Dickson, Guojun Bu, Takahisa Kanekiyo
Septic patients frequently develop cognitive impairment that persists beyond hospital discharge. The impact of sepsis on electrophysiological and molecular determinants of learning is underexplored. We observed that mouse survivors of sepsis or endotoxemia experienced loss of hippocampal long-term potentiation (LTP), a brain-derived neurotrophic factor (BDNF)-mediated process responsible for spatial memory formation. Memory impairment occurred despite preserved hippocampal BDNF content and could be reversed by stimulation of BDNF signaling, suggesting the presence of a local BDNF inhibitor. Sepsis is associated with degradation of the endothelial glycocalyx, releasing heparan sulfate fragments (of sufficient size and sulfation to bind BDNF) into the circulation. Heparan sulfate fragments penetrated the hippocampal blood-brain barrier during sepsis and inhibited BDNF-mediated LTP. Glycoarray approaches demonstrated that heparan sulfate’s avidity for BDNF increased with sulfation at the 2-O-position of iduronic acid and N-position of glucosamine. Circulating heparan sulfate in endotoxemic mice and septic humans was enriched in 2-O- and N-sulfated disaccharides; furthermore, the presence of these sulfation patterns in the plasma of septic patients at intensive care unit (ICU) admission predicted persistent cognitive impairment 14 days after ICU discharge or at hospital discharge. Our findings indicate that circulating 2-O- and N-sulfated heparan sulfate fragments contribute to septic cognitive impairment.
Joseph A. Hippensteel, Brian J. Anderson, James E. Orfila, Sarah A. McMurtry, Robert M. Dietz, Guowei Su, Joshay A. Ford, Kaori Oshima, Yimu Yang, Fuming Zhang, Xiaorui Han, Yanlei Yu, Jian Liu, Robert J. Linhardt, Nuala J. Meyer, Paco S. Herson, Eric P. Schmidt
Parisa Malekzadeh, Anna Pasetto, Paul F. Robbins, Maria R. Parkhurst, Biman C. Paria, Li Jia, Jared J. Gartner, Victoria Hill, Zhiya Yu, Nicholas P. Restifo, Abraham Sachs, Eric Tran, Winifred Lo, Robert P.T. Somerville, Steven A. Rosenberg, Drew C. Deniger
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
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
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
Graft-versus-host disease (GVHD) in the gastrointestinal (GI) tract remains the major cause of morbidity and nonrelapse mortality after BM transplantation (BMT). The Paneth cell protein regenerating islet-derived 3α (REG3α) is a biomarker specific for GI GVHD. REG3α serum levels rose in the systematic circulation as GVHD progressively destroyed Paneth cells and reduced GI epithelial barrier function. Paradoxically, GVHD suppressed intestinal REG3γ (the mouse homolog of human REG3α), and the absence of REG3γ in BMT recipients intensified GVHD but did not change the composition of the microbiome. IL-22 administration restored REG3γ production and prevented apoptosis of both intestinal stem cells (ISCs) and Paneth cells, but this protection was completely abrogated in Reg3g−/− mice. In vitro, addition of REG3α reduced the apoptosis of colonic cell lines. Strategies that increase intestinal REG3α/γ to promote crypt regeneration may offer a novel, nonimmunosuppressive approach for GVHD and perhaps for other diseases involving the ISC niche, such as inflammatory bowel disease.
Dongchang Zhao, Yeung-Hyen Kim, Seihwan Jeong, Joel K. Greenson, Mohammed S. Chaudhry, Matthias Hoepting, Erik R. Anderson, Marcel R.M. van den Brink, Jonathan U. Peled, Antonio L.C. Gomes, Ann E. Slingerland, Michael J. Donovan, Andrew C. Harris, John E. Levine, Umut Ozbek, Lora V. Hooper, Thaddeus S. Stappenbeck, Aaron Ver Heul, Ta-Chiang Liu, Pavan Reddy, James L.M. Ferrara
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
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
In the era of combined antiretroviral therapy (cART), lung diseases such as chronic bronchitis (CB) and COPD are common among persons living with HIV (PLWH), particularly smokers. Although smoking is highly prevalent among PLWH, HIV may be an independent risk factor for lung diseases; however, the role of HIV and cigarette smoke (CS) and their potential interaction in the development of chronic lung diseases among PLWH has not been delineated. To investigate this interaction, cynomolgus macaques were exposed to CS and/or simian-adapted human immunodeficiency virus (SHIV) and treated with cART. The development of CB and the lung functions were evaluated following CS±SHIV treatment. The results showed that in the lung, SHIV was a strong independent risk factor for goblet cell metaplasia/hyperplasia and mucus formation, MUC5AC synthesis, loss of tight junction proteins, and increased expression of Th2 cytokines/transcription factors. In addition, SHIV and CS synergistically reduced the lung function and increased the extrathoracic tracheal ring thickness. Interestingly, SHIV-infection generated significant numbers of HIV-gp120+ epithelial cells (HGECs) in small airways and alveoli and their numbers doubled in CS+SHIV-infected lungs. We conclude that even with cART, SHIV independently induces CB and pro-COPD changes in the lung and the effects are exacerbated by CS.
Hitendra S. Chand, Rodrigo Vazquez-Guillamet, Christopher M. Royer, Karin Rudolph, Neerad C. Mishra, Shashi P. Singh, Shah S. Hussain, Edward G. Barrett, Shannon Callen, Siddappa N. Byrareddy, Maria Cristina Vazquez Guillamet, Jawad Abukhalaf, Aryaz Sheybani, Vernat Exil, Veena Raizada, Hemant Agarwal, Madhavan Nair, Francois Villinger, Shilpa Buch, Mohan Sopori
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