Clonally expanded HIV-1 proviruses with 5’-Leader defects can give rise to nonsuppressible residual viremia

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Abstract

BACKGROUND. Antiretroviral therapy (ART) halts HIV-1 replication, decreasing viremia to below the detection limit of clinical assays. However, some individuals experience persistent nonsuppressible viremia (NSV) originating from CD4+ T cell clones carrying infectious proviruses. Defective proviruses represent over 90% of all proviruses persisting during ART and can express viral genes, but whether they can cause NSV and complicate ART management is unknown. METHODS. We carried an in-depth characterization of proviruses causing NSV in 4 study participants with optimal adherence and no drug resistance. We investigated the impact of the observed defects on 5’-Leader RNA properties, virus infectivity, and gene expression. Integration-site specific assays were used to track these proviruses over time and among cell subsets. RESULTS. Clones carrying proviruses with 5’-Leader defects can cause persistent NSV up to ~103 copies/mL. These proviruses had small, often identical deletions or point mutations involving the major splicing donor site (MSD) and showed partially reduced RNA dimerization and nucleocapsid binding. Nevertheless, they were inducible and produced non-infectious virions containing viral RNA but lacking Envelope. CONCLUSION. These findings show that proviruses with 5’-Leader defects in CD4+ T cell clones can give rise to NSV, affecting clinical care. Sequencing of the 5’-Leader can help understanding failure to completely suppress viremia. FUNDING. Office of the NIH Director and National Institute of Dental & Craniofacial Research, NIH; Howard Hughes Medical Institute; Johns Hopkins University Center for AIDS Research; National Institute for Allergy and Infectious Diseases, NIH, to the PAVE, BEAT-HIV and DARE Martin Delaney collaboratories.

Authors

Jennifer A. White, Fengting Wu, Saif Yasin, Milica Moskovljevic, Joseph Varriale, Filippo Dragoni, Angelica Camilo Contreras, Jiayi Duan, Mei Y. Zheng, Ndeh F. Tadzong, Heer B. Patel, Jeanelle Mae C. Quiambao, Kyle Rhodehouse, Hao Zhang, Jun Lai, Subul A. Beg, Michael Delannoy, Christin Kilcrease, Christopher J. Hoffmann, Sébastien Poulin, Frédéric Chano, Cecile Tremblay, Jerald Cherian, Patricia Barditch-Crovo, Natasha Chida, Richard D. Moore, Michael F. Summers, Robert F. Siliciano, Janet D. Siliciano, Francesco R. Simonetti

Intestinal neuropod GUCY2C regulates visceral pain

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Abstract

Visceral pain (VP) is a global problem with complex etiologies and limited therapeutic options. Guanylyl cyclase C (GUCY2C), an intestinal receptor producing cyclic GMP which regulates luminal fluid secretion, has emerged as a therapeutic target for VP. Indeed, FDA-approved GUCY2C agonists ameliorate VP in patients with chronic constipation syndromes, although analgesic mechanisms remain obscure. Here, we reveal that intestinal GUCY2C is selectively enriched in neuropod cells, a type of enteroendocrine cell that synapses with submucosal neurons in mice and humans. GUCY2CHigh neuropod cells associate with co-cultured dorsal root ganglia neurons and induce hyperexcitability, reducing the rheobase and increasing the resulting number of evoked action potentials. Conversely, the GUCY2C agonist linaclotide eliminated neuronal hyperexcitability produced by GUCY2C-sufficient, but not GUCY2C-deficient, neuropod cells, an effect independent of bulk epithelial cells or extracellular cGMP. Genetic elimination of intestinal GUCY2C amplified nociceptive signaling and VP that was comparable to chemically-induced VP but refractory to linaclotide. Importantly, eliminating GUCY2C selectively in neuropod cells also increased nociceptive signaling and VP that was refractory to linaclotide. In the context of loss of GUCY2C hormones in patients with VP, these observations suggest a specific role for neuropod GUCY2C signaling in the pathophysiology and treatment of these pain syndromes.

Authors

Joshua R. Barton, Annie K. Londregan, Tyler D. Alexander, Ariana A. Entezari, Shely Bar-Ad, Lan Cheng, Angelo C. Lepore, Adam E. Snook, Manuel Covarrubias, Scott A. Waldman

Leucine-973 is a crucial residue differentiating insulin and IGF-1 receptor signaling

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Abstract

Insulin and IGF-1 receptors (IR/IGF1R) are highly homologous and share similar signaling systems, but each has a unique physiological role, with IR primarily regulating metabolic homeostasis and IGF1R regulating mitogenic control and growth. Here, we showed that replacement of a single amino acid at position 973, just distal to the NPEY motif in the intracellular juxtamembrane region, from leucine, which is highly-conserved in IRs, to phenylalanine, the highly-conserved homologous residue in IGF1Rs, resulted in decreased IRS-1-PI3K-Akt-mTORC1 signaling and increased of Shc-Gab1-MAPK-cell cycle signaling. As a result, cells expressing L973F-IR exhibited decreased insulin-induced glucose uptake, increased cell growth and impaired receptor internalization. Mice with knockin of the L973F-IR showed similar alterations in signaling in vivo, and this leaded to decreased insulin sensitivity, a modest increase in growth and decreased weight gain when challenged with high-fat diet. Thus, leucine973 in the juxtamembrane region of the IR acts as a crucial residue differentiating IR signaling from IGF1R signaling.

Authors

Hirofumi Nagao, Weikang Cai, Bruna Brasil Brandão, Nicolai J. Wewer Albrechtsen, Martin Steger, Arijeet K. Gattu, Hui Pan, Jonathan M. Dreyfuss, F. Thomas Wunderlich, Matthias Mann, C. Ronald Kahn

Targeting myeloid cell coagulation signaling blocks MAP kinase/TGF-β1 driven fibrotic remodeling in ischemic heart failure

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Abstract

Despite major advances in acute interventions of myocardial infarction (MI), adverse cardiac remodeling and excess fibrosis post MI causing ischemic heart failure (IHF) remains a leading cause of death worldwide. Here we identify a pro-fibrotic coagulation signaling pathway that can be targeted for improved cardiac function following MI with persistent ischemia. Quantitative phospho-proteomics of cardiac tissue revealed an up-regulated mitogen activated protein kinase (MAPK) pathway in human IHF. Intervention in this pathway with trametinib improves myocardial function and prevents fibrotic remodeling in a murine model of non-reperfused MI. MAPK activation in MI requires myeloid cell signaling of protease activated receptor 2 linked to the cytoplasmic domain of the coagulation initiator tissue factor (TF). They act upstream of pro-oxidant NOX2 NADPH oxidase, ERK1/2 phosphorylation, and activation of pro-fibrotic transforming growth factor β1 (TGF-β1). Specific targeting with the TF inhibitor nematode anticoagulant protein c2 (NAPc2) starting one day after established experimental MI averts IHF. Increased TF cytoplasmic domain phosphorylation in circulating monocytes from patients with sub-acute MI identifies a potential thrombo-inflammatory biomarker reflective of increased risk for IHF and suitable for patient selection to receive targeted TF inhibition therapy.

Authors

Venkata Garlapati, Michael Molitor, Thomas Michna, Gregory S. Harms, Stefanie Finger, Rebecca Jung, Jeremy Lagrange, Panagiotis Efentakis, Johannes Wild, Maike Knorr, Susanne Karbach, Sabine Wild, Ksenija Vujacic-Mirski, Thomas Münzel, Andreas Daiber, Moritz Brandt, Tommaso Gori, Hendrik Milting, Stefan Tenzer, Wolfram Ruf, Philip Wenzel

The UBE2C/CDH1/DEPTOR axis is an oncogene-tumor suppressor cascade in lung cancer cells

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Abstract

Ubiquitin-conjugating enzyme E2C (UBE2C) mediates the ubiquitylation chain formation via the K11 linkage. While previous in vitro studies showed that UBE2C plays a growth-promoting role in cancer cell lines, the underlying mechanism remains elusive. Still unknown is whether and how UBE2C plays a promoting role in vivo. Here we reported that UBE2C is indeed essential for growth and survival of lung cancer cells harboring Kras mutations, and UBE2C is required for KrasG12D-induced lung tumorigenesis, since Ube2c deletion significantly inhibits tumor formation and extends the life-span of mice. Mechanistically, KrasG12D induces expression of UBE2C, which couples with APC/CCDH1 E3 ligase to promote ubiquitylation and degradation of DEPTOR, leading to activation of the mTORC signals. Importantly, DEPTOR levels are fluctuated during cell cycle progression in a manner dependent of UBE2C and CDH1, indicating their physiological connection. Finally, Deptor deletion fully rescues the tumor inhibitory effect of Ube2c deletion in the KrasG12D lung tumor model, indicating a causal role of Deptor. Taken together, our study shows that the UBE2C/CDH1/DEPTOR axis forms an oncogene-tumor suppressor cascade that regulates cell cycle progression and autophagy and validates that UBE2C is an attractive target for lung cancer associated with Kras mutations.

Authors

Shizhen Zhang, Xiahong You, Yawen Zheng, Yanwen Shen, Xiufang Xiong, Yi Sun

Loss of LGR4/GPR48 causes severe neonatal salt-wasting due to disrupted WNT signaling altering adrenal zonation

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Abstract

Disorders of isolated mineralocorticoid deficiency causing potentially life-threatening salt-wasting crisis early in life have been associated with gene variants of aldosterone biosynthesis or resistance, but in some patients no such variants are found. WNT/β-catenin signaling is crucial for differentiation and maintenance of the aldosterone producing adrenal zona glomerulosa (zG). We describe a highly consanguineous family with multiple perinatal deaths or infants presenting at birth with failure to thrive, severe salt-wasting crises associated with isolated hypoaldosteronism, nail anomalies, short stature, and deafness. Whole exome sequencing revealed a homozygous splice variant in the R-SPONDIN receptor LGR4 gene (c.618-1G>C) regulating WNT signaling. The resulting transcripts affected protein function and stability, and resulted in loss of Wnt/β-catenin signaling in vitro. The impact of LGR4 inactivation was analyzed by adrenal cortex specific ablation of Lgr4, using Lgr4Flox/Flox mated with Sf1:Cre mice. Inactivation of Lgr4 within the adrenal cortex in the mouse model caused decreased WNT signaling, aberrant zonation with deficient zG and reduced aldosterone production. Thus, human LGR4 mutations establish a direct link between LGR4 inactivation and decreased canonical WNT signaling with abnormal zG differentiation and endocrine function. Therefore, variants in WNT signaling and its regulators should systematically be considered in familial hyperreninemic hypoaldosteronism.

Authors

Cécily Lucas, Kay-Sara Sauter, Michael Steigert, Delphine Mallet, James Wilmouth Jr., Julie Olabe, Ingrid Plotton, Yves Morel, Daniel Aeberli, Franca Wagner, Hans Clevers, Amit V. Pandey, Pierre Val, Florence Roucher-Boulez, Christa E. Fluck

ClinCirc identifies alterations of the circadian peripheral oscillator in critical care patients

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Abstract

BACKGROUND. Assessing circadian rhythmicity from infrequently sampled data is challenging, however this type of data is often encountered when measuring circadian transcripts in hospitalised patients. METHODS. We present ClinCirc. This method combines two existing mathematical methods (Lomb-Scargle periodogram and cosinor) sequentially, and is designed to measure circadian oscillations from infrequently sampled clinical data. The accuracy of this method was compared against 9 other methods using simulated and frequently sampled biological data. ClinCirc was then evaluated in 13 ICU patients as well as in a separate cohort of 29 kidney transplant recipients. Finally, the consequences of circadian alterations were investigated in a retrospective cohort of 726 kidney transplant recipients. RESULTS. ClinCirc had comparable performance to existing methods for analysing simulated data or clock transcript expression of healthy volunteers. It had improved accuracy compared to the cosinor method in evaluating circadian parameters in PER2::luc cell lines. In ICU patients, it was the only method investigated to suggest that loss of circadian oscillations in the peripheral oscillator was associated with inflammation, a feature widely reported in animal models. Additionally, ClinCirc was able to detect other circadian alterations, including a phase shift following kidney transplantation that was associated with the administration of glucocorticoids. This phase shift could explain why a significant complication of kidney transplantation (delayed graft dysfunction) oscillates according to the time-of-day kidney transplantation is performed. CONCLUSION. ClinCirc analysis of the peripheral oscillator reveals important clinical associations in hospitalised patients. FUNDING. UKRI, NIHR, EPSRC, NIAA, Asthma+Lung UK, Kidneys for Life.

Authors

Peter S. Cunningham, Gareth B. Kitchen, Callum Jackson, Stavros Papachristos, Thomas Springthorpe, David van Dellen, Julie E. Gibbs, Timothy W. Felton, Anthony J. Wilson, Jonathan Bannard-Smith, Martin K. Rutter, Thomas House, Paul Dark, Titus Augustine, Ozgur E. Akman, Andrew L. Hazel, John F. Blaikley

Mechanisms and treatments of neuropathic itch in a mouse model of lymphoma

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Abstract

Our understanding of neuropathic itch is limited, due to the lack of relevant animal models. Patients with cutaneous T-cell lymphoma (CTCL) suffer from severe itching. Here we characterize a mouse model of chronic itch with remarkable lymphoma growth, immune cell accumulation, and persistent pruritus. Intradermal CTCL inoculation produces time-dependent changes in nerve innervations in lymphoma-bearing skin. In the early-phase (20 days), CTCL causes hyper-innervations in the epidermis. However, chronic itch is associated with loss of epidermal nerve fibers in the late-phases (40 and 60 days). CTCL is also characterized by marked nerve innervations in mouse lymphoma. Blockade of C-fibers reduced pruritus at early- and late-phases, whereas blockade of A-fibers only suppressed late-phase itch. Intrathecal gabapentin injection reduced late-phase but not early-phase pruritus. IL-31 is upregulated in mouse lymphoma, while its receptor Il31ra was persistently upregulated in Trpv1-expressing sensory neurons in CTCL mice. Intratumoral anti-IL-31 treatment effectively suppressed CTCL-induced scratching and alloknesis (mechanical itch). Finally, intrathecal administration of TLR4 antagonist attenuated pruritus in early and late phases and in both sexes. Collectively, we have established a mouse model of neuropathic and cancer itch with relevance to human disease. Our findings also suggest distinct mechanisms underlying acute, chronic, and neuropathic itch.

Authors

Ouyang Chen, Qianru He, Qingjian Han, Kenta Furutani, Yun Gu, Madelynne Olexa, Ru-Rong Ji

Mini-dCas13X-mediated RNA editing restores dystrophin expression in a humanized mouse model of Duchenne muscular dystrophy

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Abstract

Approximately 10% of monogenic diseases are caused by nonsense point mutations that generate premature termination codons (PTCs), resulting in a truncated protein and nonsense-mediated decay of the mutant mRNAs. Here, we demonstrate a mini-dCas13X-mediated RNA adenine base editing (mxABE) strategy to treat nonsense mutation-related monogenic diseases via A-to-G editing in a genetically humanized mouse model of Duchenne muscular dystrophy (DMD). Initially, we identified a nonsense point mutation (c.4174C>T, p.Gln1392*) in the DMD gene of a patient and validated its pathogenicity in humanized mice. In this model, single adeno-associated virus (AAV)-packaged mxABE reached A-to-G editing rates up to 84% in vivo, which is at least 20-fold greater compared to rates reported in previous studies using other RNA-editing modalities. Furthermore, mxABE restored robust expression of dystrophin protein to over 50% of wild-type (WT) levels by enabling PTC read-through in multiple muscle tissues. Importantly, systemic delivery of mxABE by AAV also rescued dystrophin expression to averages of 37%, 6%, and 54% of WT levels in the diaphragm, tibialis anterior, and heart muscle, respectively, as well as rescued muscle function. Our data strongly suggest that mxABE-based strategies may be a viable new treatment modality for DMD and other monogenic diseases.

Authors

Guoling Li, Ming Jin, Zhifang Li, Qingquan Xiao, Jiajia Lin, Dong Yang, Yuanhua Liu, Xing Wang, Long Xie, Wenqin Ying, Haoqiang Wang, Erwei Zuo, Linyu Shi, Ning Wang, Wanjin Chen, Chunlong Xu, Hui Yang

Glucose- and glutamine-dependent bioenergetics sensitize bone mechanoresponse after unloading by modulating osteocyte calcium dynamics

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Abstract

Disuse osteoporosis is a metabolic bone disease resulted from skeletal unloading (e.g., during extended bed rest, limb immobilization, and spaceflight), and the slow and insufficient bone recovery during re-ambulation remains an unresolved medical challenge. Here, we demonstrated that loading-induced increase in bone architecture/strength was suppressed in skeletons previously exposed to unloading. This reduction in bone mechanosensitivity was directly associated with attenuated osteocytic Ca2+ oscillatory dynamics. The unloading-induced compromised osteocytic Ca2+ response to reloading resulted from the HIF-1α/PDK1 axis-mediated increase in glycolysis, and a subsequent reduction in ATP synthesis. HIF-1α also transcriptionally induced substantial glutaminase 2 expression and thereby glutamine addiction in osteocytes. Inhibition of glycolysis by blocking PDK1 or glutamine supplementation restored the mechanosensitivity in those skeletons with previous unloading by fueling the tricarboxylic acid cycle and rescuing subsequent Ca2+ oscillations in osteocytes. Thus, we provide a mechanistic insight into disuse-induced deterioration of bone mechanosensitivity and a promising therapeutic approach to accelerate bone recovery after long-duration disuse.

Authors

Xiyu Liu, Zedong Yan, Jing Cai, Dan Wang, Yongqing Yang, Yuanjun Ding, Xi Shao, Xiaoxia Hao, Erping Luo, X. Edward Guo, Peng Luo, Liangliang Shen, Da Jing