Neuroscience
Abstract
Huntington’s disease (HD) is a neurodegenerative disorder caused by the expansion of CAG repeats in the gene encoding huntingtin. Since accumulation of mutant huntingtin (mHtt) leads to dysfunction of numerous cellular pathways and toxicity, reducing levels of the mutant protein represents a key therapeutic objective in HD. We found that ubiquitination of mHtt by E3 ubiquitin ligase Nedd4 promotes clearance of the mutant protein. Knockdown of Nedd4 increased toxicity of mHtt in mouse primary neurons and in a fly model of HD, suggesting the protective role of Nedd4. Importantly, levels of Nedd4 were decreased in mHtt-expressing neurons through impaired mTORC1 activity, suggesting a feedback loop of mHtt accumulation and Nedd4 reduction that leads to accumulation and, ultimately, toxicity of mHtt. These findings suggest that restoring Nedd4 activity may offer a novel therapeutic opportunity for HD.
Authors
Hyunkyung Jeong, Yiyang Qin, Fangke Xu, Katarina Trajkovic, Myung Jong Kim, Nicolas Marotta, Kana Hamada, Ravi Allada, Su Yang, Dimitri Krainc
Abstract
Among the known genetic causes of syndromic autism spectrum disorders (ASDs) are transcription factor deficiencies. In this regard, haploinsufficiency of the zinc finger and broad complex, tramtrack, bric and brac domain–containing protein 20 (ZBTB20) leads to a prototypical clinical picture, referred to as Primrose syndrome, comprising severe ASD symptoms together with intellectual disability. Here, we present a comprehensive behavioral and phenotypical characterization of Zbtb20+/– mice, a construct valid model of this thus far untreatable human condition. Zbtb20+/– mice exhibited diminished sociability, reduced vocalization, distinct repetitive behaviors, impaired cognitive flexibility, hyperactivity, and hypoalgesia. Magnetic resonance imaging revealed increased volumes of hippocampus, cerebellum, brain matter, and whole brain, confirmed by postmortem brain weight measurements. Due to our previous observation of enhanced ZBTB20 expression in CA1 pyramidal neurons upon recombinant human erythropoietin (rhEPO) injections, we anticipated a mitigating effect through rhEPO treatment of Zbtb20 deficiency/Primrose syndrome. Indeed, after 3 weeks of alternate-day rhEPO injections, a remarkable improvement in the behavioral phenotype was observed. Our results highlight rhEPO as promising treatment for Primrose syndrome.
Authors
Martin Hindermann, Justus B.H. Wilke, Yasmina Curto, Stefan N. Oline, Vinicius Daguano Gastaldi, Umer Javed Butt, Rakshit Dadarwal, Umut Çakır, Anja Ronnenberg, Kurt Hammerschmidt, Susann Boretius, Anastassia Stoykova, Anton B. Tonchev, Klaus-Armin Nave, Manvendra Singh, Hannelore Ehrenreich
Abstract
Pancreatic cancer is a highly innervated gastrointestinal disease in which sympathetic nerves play a critical role in modulating tumor growth and the tumor microenvironment (TME). While recent studies suggest that sympathetic nerves influence various TME components, including lymphoid and myeloid immune cells, their interactions with cancer-associated fibroblasts (CAFs) remain poorly understood. CAFs are a hallmark of pancreatic tumors and are known to upregulate axon guidance and neuroactive cues, suggesting a potential feedback loop with tumor-innervating nerves. Here, we investigated the bidirectional crosstalk between sympathetic nerves and CAFs in human and mouse pancreatic tumors. Using a chemo-genetic ablation model, we selectively eliminated pancreatic sympathetic nerves and found that denervation significantly reduced tumor size in female mice. To further dissect this interaction, we established co-culture systems with immortalized pancreatic fibroblasts and primary sympathetic neuron explants, identifying key transcriptional changes driven by CAF-sympathetic nerve signaling. Our findings demonstrated that sympathetic signaling enhanced CAF activation and extracellular matrix remodeling, while activated CAFs, in turn, induced transcriptional programs in sympathetic neurons associated with nerve injury response. These results establish CAFs as central mediators of the tumor-supportive role of sympathetic nerves, offering further insights into the neural regulation of pancreatic cancer progression.
Authors
Ariana L. Sattler, Parham Diba, Kevin Hawthorne, Carl Pelz, Joe Grieco, Tetiana Korzun, Bryan Chong, M.J. Kuykendall, Rosalie C. Sears, Daniel L. Marks, Mara H. Sherman, Teresa A Zimmers, S. Ece Eksi
Abstract
Oxidative signaling is a central mechanism in alcohol-induced injury and has a strong implication in blood-brain barrier (BBB) dysregulation and neuroinflammation. Here, by targeting oxidative signaling, we hypothesized an innovative approach to develop a clinically relevant therapeutic strategy for alleviating alcohol-mediated neurovascular damage. To accomplish this, we enhanced the endogenous activity of Nrf2 (nuclear factor E2-related factor 2) by treating with an Nrf2 activator III TAT peptide (Nrf2 peptide, NP) and investigated the neuroprotective role of Nrf2 in promoting antioxidant defense properties and reducing BBB damage and transmigration of leukocytes to the brain following alcohol ingestion. We administered the NP subcutaneously to alcohol-ingested mice and evaluated its therapeutic potential in alleviating alcohol-associated neurovascular impairments. We compared the results with control peptide (random sequence with TAT)-treated animals. The studies showed that the NP treatment preserved the oxidant-antioxidant balance, downregulated ICAM-1 and its receptors, and mitigated BBB damage and leukocyte infiltration into the brain. We validated the effect of the NP in Nrf2 knock-out (KO) mice (Nrf2−/−). Thus, this study demonstrates NP’s neurovascular protective effects by regulating the oxidant-antioxidant balance, reducing oxidative stress-induced BBB disruption, and limiting transmigration of immune cells to the brain in a mouse model of alcohol ingestion.
Authors
Bibhuti B. Saikia, Saleena Alikunju, Yemin A. Poovanthodi, Zayan Kassim, P. M. Abdul Muneer
Abstract
Hirschsprung disease (HSCR) is a congenital intestinal disorder characterized by the absence of ganglia in the distal intestine. Despite surgical resection of the aganglionic intestine and pull-through surgery, HSCR patients still experience bowel dysfunction, indicating that latent abnormalities may also exist in the proximal ganglionic intestine. To elucidate possible causes of postoperative bowel dysfunction in HSCR, we investigated differences in the proximal ganglionic intestine using an animal model of HSCR (Ednrb-null mice) and validated our findings in tissue from human HSCR patients. We found that the proximal ganglionic colon of HSCR mice exhibited greater stiffness and fibrosis than their wild-type littermates. Similarly, submucosal fibrosis was significantly greater in the proximal ganglionic intestine of HSCR patients than in intestinal tissue from age and site-matched controls. Furthermore, we observed dysregulated expression of extracellular matrix (ECM)-related genes in the proximal ganglionic intestine of HSCR mice compared to controls. We conclude that increased fibrosis, stiffness, and alterations in ECM composition may contribute to persistent dysfunction of the ganglionic intestine in HSCR. These findings add to the growing body of literature that describe abnormalities in the proximal ganglionic intestine of HSCR and suggest that HSCR is not limited to the aganglionic intestine alone.
Authors
Prisca C. Obidike, Britney A. Hsu, Chioma Moneme, Oluyinka O. Olutoye II, Walker D. Short, Mary Hui Li, Swathi Balaji, Yuwen Zhang, Sundeep G. Keswani, Lily S. Cheng
Abstract
Mutation of KRAS in endothelial cells (KRAS-EC) leads to intracerebral hemorrhage (ICH) in brain arteriovenous malformations (bAVM), resulting in severe disabilities or even death. However, it is unclear what causes this hemorrhagic conversion of bAVM. Here, using a locally established, clinically-relevant sporadic bAVM mouse model, created by overexpressing mutant KRAS (KRASG12V) in the brain EC, we demonstrate that KRAS-EC act as trigger for microglia (MG) activation and infiltration of macrophages (Mϕ). Using three-dimensional immunostaining approach with cleared human and mouse bAVM tissues, we demonstrate an abundance of MG/Mϕ around the bAVM nidus. The presence of MG/Mϕ are correlated to the blood-brain barrier leakage in bAVM area. Time-lapsed intravital imaging in Cx3cr1-gfp;Ccr2-rfp reporter mice demonstrate the dynamic activation of MG and infiltration of Mϕ toward mutant KRAS-modified dysplastic vessels. Importantly, a time course analysis showed that these activated/infiltrated MG/Mϕ are present around the bAVMs prior to hemorrhagic conversion, and controlled depletion of MG/Mϕ reduced ICH incidence in bAVM. Inhibition of MG/Mϕ with long-term minocycline treatment attenuated the incidence of ICHs around bAVMs. Our study indicates that MG/Mϕ are involved in destabilization of KRAS-induced bAVM, leading to hemorrhagic conversion/ICH. Thus, modulation of MG/Mϕ may reduce ICH risk in bAVM patients.
Authors
Hyejin Park, Jung-Eun Park, Bridger H. Freeman, Bosco Seong Kyu Yang, Shun-Ming Ting, Alexander K. Suh, Jude P.J. Savarraj, Shuning Huang, Jakob Körbelin, Huimahn Alex Choi, Sean P. Marrelli, Jaroslaw Aronowski, Peng Roc Chen, Eunhee Kim, Eun S. Park
Abstract
Angelman syndrome (AS) is a neurodevelopmental disorder caused by loss of the maternal UBE3A allele, the sole source of UBE3A in mature neurons due to epigenetic silencing of the paternal allele. Although emerging therapies are being developed to restore UBE3A expression by activating the dormant paternal UBE3A allele, existing mouse models for such preclinical studies have limited throughput and utility, creating bottlenecks for both in vitro therapeutic screening and in vivo characterization. To address this, we developed the Ube3a-INSG dual-reporter knock-in mouse, in which an IRES-Nanoluciferase-T2A-Sun1-sfGFP (INSG) cassette was inserted downstream of the endogenous Ube3a stop codon. The INSG model preserves UBE3A protein levels and function while enabling two complementary allele-specific readouts: Sun1-sfGFP and Nanoluciferase. We show that Sun1-sfGFP, a nuclear envelope-localized reporter, enables single-cell fluorescence analysis, whole-brain light-sheet imaging, and nuclear quantification by flow cytometry. Further, Nanoluciferase supports high-throughput luminescence assays for sensitive pharmacological profiling in cultured neurons and non-invasive in vivo bioluminescence imaging for pharmacodynamic assessment. By combining scalable screening, cellular analysis, and real-time in vivo monitoring in a single model, the Ube3a-INSG dual-reporter mouse provides a powerful platform to accelerate therapeutic development centered on UBE3A.
Authors
Hanna Vihma, Lucas M. James, Hannah C. Nourie, Audrey L. Smith, Siyuan Liang, Carlee A. Friar, Tasmai Vulli, Lei Xing, Dale O. Cowley, Alain C. Burette, Benjamin D. Philpot
Abstract
Authors
Rimas V. Lukas, Ruochen Du, Harrshavasan Congivaram, Kathleen McCortney, Karan Dixit, Craig Horbinski, Margaret Schwartz, Raymond Lezon, Lauren Singer, Ditte Primdahl, Jigisha Thakkar, Amy B. Heimberger, Roger Stupp, Priya Kumthekar
Potentiation of fentanyl-induced respiratory depression by alcohol is not fully reversed by naloxone
Abstract
The high frequency of opioid overdose deaths often involves co-use of alcohol, which is reported in approximately 30% of fentanyl fatalities. Both substances depress respiratory function, and their combined effects can be lethal. The present study investigated physiological parameters of respiratory-depressant effects of fentanyl when co-administered with alcohol and its sensitivity to naloxone reversal using whole-body plethysmography in male and female Long-Evans rats. Administration of a high, sedative-like dose of alcohol alone or fentanyl alone resulted in no mortality, but fentanyl+alcohol led to mortality rates of 42% and 33% in females and males, respectively. The fentanyl+alcohol combination reduced minute ventilation and increased apneic pauses compared with either drug alone. Lower, binge-like alcohol doses, when combined with fentanyl, also amplified respiratory depression. Pretreatment with naloxone did not fully restore normal respiration. Naloxone administered after fentanyl+alcohol transiently reversed the decrease in minute ventilation but did not reverse apneic pauses. Fentanyl-dependent rats were partially tolerant to fentanyl- and fentanyl+alcohol-induced respiratory depression, but alcohol-dependent rats exhibited sensitization to alcohol- and fentanyl+alcohol-induced apnea. These findings highlight physiological parameters of severe respiratory risks with fentanyl+alcohol co-use, which are inadequately reversed by naloxone, underscoring the need for targeted strategies to manage opioid+alcohol overdoses.
Authors
Emma V. Frye, Lyndsay E. Hastings, Aniah N. Matthews, Adriana Gregory-Flores, Janaina C.M. Vendruscolo, Lindsay A. Kryszak, Shelley N Jackson, Aidan J. Hampson, Nora D. Volkow, Leandro F. Vendruscolo, Renata C.N. Marchette, George F. Koob
Abstract
Acute severe joint pain is a major symptom in gouty arthritis (GA), and its adequate treatment represents an unmet medical need. Mrgprb2, a specific mast cell receptor, has been implicated in the generation of chronic pain by mobilizing mast cell degranulation, yet its significance in GA pain and joint inflammation is still not well defined. Here, we found that Mrgprb2 was expressed in mouse synovial mast cells. In a murine model of GA, acute blockade or genetic deletion of Mrgprb2 significantly attenuated arthritis pain and hyperexcitability of joint nociceptors with significant reductions in innate immune cell recruitment in the synovium. Under naive conditions, activation of synovial Mrgprb2 was sufficient to excite peripheral terminals of joint nociceptors to induce acute joint hypernociception via the mobilization of mast cell degranulation. Additionally, the level of the neuropeptide substance P (SP) was elevated in the synovium of GA model mice. Using humanized MRGPRX2-knockin mice, we revealed that SP contributed to joint pain and inflammation by activating mast cells through Mrgprb2/MRGPRX2. These findings suggest that synovial mast cell–expressed Mrgprb2/MRGPRX2 merits consideration as a key neuroimmune player and a potential therapeutic target for treating GA pain and joint inflammation.
Authors
Lin Yang, Chengxi Liu, Jin Xiao, Yu Song, Huan Chen, Dan Li, Cong Zou, Tao Hong, Yinglan Liu, Dake Qi, Nathachit Limjunyawong, Wenjie Liu, Lintao Qu
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