Research Article
Abstract
The nucleolus is a membraneless organelle and an excellent stress sensor. Any changes in its architecture or composition lead to nucleolar stress, resulting in cell cycle arrest and interruption of ribosomal activity, critical factors in aging and cancer. In this study, we identified and described the pivotal role of the RNA-binding protein HNRNPK in ribosome and nucleolar dynamics. We developed an in vitro model of endogenous HNRNPK overexpression and an in vivo mouse model of ubiquitous HNRNPK overexpression. These models showed disruptions in translation as the HNRNPK overexpression caused alterations in the nucleolar structure, resulting in p53-dependent nucleolar stress, cell cycle arrest, senescence, and bone marrow failure phenotype, similar to what is observed in patients with ribosomopathies. Together, our findings identify HNRNPK as a master regulator of ribosome biogenesis and nucleolar homeostasis through p53, providing what we believe to be a new perspective on the orchestration of nucleolar integrity, ribosome function and cellular senescence.
Authors
Pedro Aguilar-Garrido, María Velasco-Estévez, Miguel Ángel Navarro-Aguadero, Álvaro Otero-Sobrino, Marta Ibáñez-Navarro, Miguel Ángel Marugal, María Hernández-Sánchez, Prerna Malaney, Ashley Rodriguez, Oscar Benitez, Xiaroui Zhang, Marisa J.L. Aitken, Alejandra Ortiz-Ruiz, Diego Megías, Manuel Pérez, Gadea Mata, Jesús Gomez, Miguel Lafarga, Orlando Domínguez, Osvaldo Graña-Castro, Eduardo Caleiras, Pilar Ximénez-Embun, Marta Isasa, Paloma Jimena de Andres, Sandra Rodríguez-Perales, Raúl Torres-Ruiz, Enrique Revilla, Rosa María García-Martín, Daniel Azorín, Josune Zubicaray, Julián Sevilla, Oleksandra Sirozh, Vanesa Lafarga, Joaquín Martínez-López, Sean M. Post, Miguel Gallardo
Abstract
The progression of metabolic dysfunction–associated steatotic liver disease (MASLD) to metabolic dysfunction–associated steatohepatitis (MASH) involves alterations in both liver-autonomous and systemic metabolism that influence the liver’s balance of fat accretion and disposal. Here, we quantify the contributions of hepatic oxidative pathways to liver injury in MASLD-MASH. Using NMR spectroscopy, UHPLC-MS, and GC-MS, we performed stable isotope tracing and formal flux modeling to quantify hepatic oxidative fluxes in humans across the spectrum of MASLD-MASH, and in mouse models of impaired ketogenesis. In humans with MASH, liver injury correlated positively with ketogenesis and total fat oxidation, but not with turnover of the tricarboxylic acid cycle. Loss-of-function mouse models demonstrated that disruption of mitochondrial HMG-CoA synthase (HMGCS2), the rate-limiting step of ketogenesis, impairs overall hepatic fat oxidation and induces an MASLD-MASH–like phenotype. Disruption of mitochondrial β-hydroxybutyrate dehydrogenase (BDH1), the terminal step of ketogenesis, also impaired fat oxidation, but surprisingly did not exacerbate steatotic liver injury. Taken together, these findings suggest that quantifiable variations in overall hepatic fat oxidation may not be a primary determinant of MASLD-to-MASH progression, but rather that maintenance of ketogenesis could serve a protective role through additional mechanisms that extend beyond overall rates of fat oxidation.
Authors
Eric D. Queathem, David B. Stagg, Alisa B. Nelson, Alec B. Chaves, Scott B. Crown, Kyle Fulghum, D. Andre d’Avignon, Justin R. Ryder, Patrick J. Bolan, Abdirahman Hayir, Jacob R. Gillingham, Shannon Jannatpour, Ferrol I. Rome, Ashley S. Williams, Deborah M. Muoio, Sayeed Ikramuddin, Curtis C. Hughey, Patrycja Puchalska, Peter A. Crawford
Abstract
Cancer cachexia is a multifactorial condition characterized by skeletal muscle wasting that impairs quality of life and longevity for many cancer patients. A greater understanding of the molecular etiology of this condition is needed for effective therapies to be developed. We performed a quantitative proteomic analysis of skeletal muscle from cachectic pancreatic ductal adenocarcinoma (PDAC) patients and non-cancer controls, followed by immunohistochemical analyses of muscle cross sections. These data provide evidence of a local inflammatory response in muscles of cachectic PDAC patients, including an accumulation of plasma proteins and recruitment of immune cells into muscle that may promote the pathological remodeling of muscle. Our data further support the complement system as a potential mediator of these processes, which we tested by injecting murine pancreatic cancer cells into wild-type mice and mice with genetic deletion of the central complement component 3 (C3–/– mice). Compared with wild-type mice, C3–/– mice showed attenuated tumor-induced muscle wasting and dysfunction and reduced immune cell recruitment and fibrotic remodeling of muscle. These studies demonstrate that complement activation contributes to the skeletal muscle pathology and dysfunction in PDAC, suggesting that the complement system may possess therapeutic potential in preserving skeletal muscle mass and function.
Authors
Andrew C. D’Lugos, Jeremy B. Ducharme, Chandler S. Callaway, Jose G. Trevino, Carl Atkinson, Sarah M. Judge, Andrew R. Judge
Meal-feeding promotes skeletal growth by ghrelin-dependent enhancement of growth hormone rhythmicity
Abstract
The physiological effect of ultradian temporal feeding patterns remains a major unanswered question in nutritional science. We have used automated and nasogastric feeding to address this question in male rodents and human volunteers. While grazing and meal-feeding reduced food intake in parallel (compared with ad libitum–fed rodents), body length and tibial epiphysial plate width were maintained in meal-fed rodents via the action of ghrelin and its receptor, GHS-R. Grazing and meal-feeding initially suppressed elevated preprandial ghrelin levels in rats, followed by either a sustained elevation in ghrelin in grazing rats or preprandial ghrelin surges in meal-fed rats. Episodic growth hormone (GH) secretion was largely unaffected in grazing rats, but meal-feeding tripled GH secretion, with burst height augmented and 2 additional bursts of GH per day. Continuous nasogastric infusion of enteral feed in humans failed to suppress circulating ghrelin, producing continuously elevated circulating GH levels with minimal rhythmicity. In contrast, bolus enteral infusion elicited postprandial ghrelin troughs accompanied by reduced circulating GH, with enhanced ultradian rhythmicity. Taken together, our data imply that the contemporary shift from regular meals to snacking behavior may be detrimental to optimal skeletal growth outcomes by sustaining circulating ghrelin at levels associated with undernourishment and diminishing GH pulsatility.
Authors
Amanda K.E. Hornsby, Richard C. Brown, Thomas W. Tilston, Harry A. Smith, Alfonso Moreno-Cabañas, Bradley Arms-Williams, Anna L. Hopkins, Katie D. Taylor, Simran K.R. Rogaly, Lois H.M. Wells, Jamie J. Walker, Jeffrey S. Davies, Yuxiang Sun, Jeffrey M. Zigman, James A. Betts, Timothy Wells
Abstract
Gestational hypertension (GH) is prevalent, with life-long health burdens for mothers and their children exposed in utero. We analyzed the nation-wide Epic Cosmos dataset and found significantly higher rates of seizures in children of mothers with GH than in children of normotensive mothers. Complementary studies of nested Iowa and Stanford cohorts and a large Taiwanese cohort also revealed significantly increased seizure risk after covariate adjustments. We modeled this association in an angiotensin (ANG) II mouse model of GH. Maternal ANG II significantly increased seizure grade and deaths elicited by pilocarpine among male but not female offspring. Electrical stimulation increased seizure grade and death across sexes in offspring from ANG II–treated dams. Proinflammatory and microglial gene expression in the brain were upregulated only in male offspring from ANG II–treated dams. Chronic phenylephrine, a GH model lacking the maternal proinflammatory aspects of ANG II, induced similar offspring seizure phenotypes. PLX5622-induced depletion of microglia or antiinflammatory pentoxifylline abolished this sensitized seizure response and lowered mortality in the ANG II model. These results suggest that GH programs offspring risk for seizures in a sex-dependent manner in humans and mice. Neuroinflammatory mechanisms may contribute to the elevated sensitivity and mortality from seizures elicited by GH exposure in utero.
Authors
Baojian Xue, Serena B. Gumusoglu, Grant Tiarks, Brittany P. Todd, Angela Wong, Donna A. Santillan, Chin-Chi Kuo, Hsiu-Yin Chiang, Rohith Ravindranath, Sophia Y. Wang, Vinit B. Mahajan, Alan Kim Johnson, Heath A. Davis, Polly Ferguson, Elizabeth A. Newell, Mark K. Santillan, Jason M. Misurac, Alexander G. Bassuk
Abstract
Myxomatous valve disease (MVD) is the most common form of cardiac valve disease in the developed world. A small fraction of MVD is syndromic and arises in association with matrix protein defects such as those in Marfan syndrome, but most MVD is acquired later in life through an undefined pathogenesis. The KLF2/4 transcription factors mediate endothelial fluid shear responses, including those required to create cardiac valves during embryonic development. Here we test the role of hemodynamic shear forces and downstream endothelial KLF2/4 in mature cardiac valves. We find that loss of hemodynamic forces in heterotopically transplanted hearts or genetic deletion of KLF2/4 in cardiac valve endothelium confers valve cell proliferation and matrix deposition associated with valve thickening, findings also observed in mice expressing the mutant fibrillin-1 protein known to cause human MVD. Transcriptomic and histologic analysis reveals increased monocyte recruitment and TGF-β signaling in both fibrillin-1–mutant valves and valves lacking hemodynamic forces or endothelial KLF2/4 function, but only loss of TGF-β/SMAD signaling rescued myxomatous changes. We observed reduced KLF2/4 expression and augmented SMAD signaling in human MVD. These studies identify hemodynamic activation of endothelial KLF2/4 as an environmental homeostatic regulator of cardiac valves and suggest that non-syndromic MVD may arise in association with disturbed blood flow across the aging valve.
Authors
Jesse A. Pace, Lauren M. Goddard, Courtney C. Hong, Liqing Wang, Jisheng Yang, Mei Chen, Yitian Xu, Martin H. Dominguez, Siqi Gao, Xiaowen Chen, Patricia Mericko-Ishizuka, Can Tan, Tsutomu Kume, Wenbao Yu, Kai Tan, Wayne W. Hancock, Giovanni Ferrari, Mark L. Kahn
Abstract
Castration-resistant prostate cancer (CRPC) marks the advanced and lethal stage of prostate cancer (PCa). TRIM28, also known as KAP1, is a transcriptional regulator recently shown to promote CRPC cell proliferation and xenograft tumor growth. Nonetheless, knowledge gaps persist regarding the mechanisms underlying TRIM28 upregulation in CRPC as well as the genomic targets regulated by TRIM28. Here, we report that TRIM28 is a E2F1 target in CRPC. Using an integrated genomic approach, we have demonstrated that TRIM28 forms a positive feedback loop to promote the transcriptional activation and genomic function of E2F1 independent of retinoblastoma (Rb) status. Furthermore, we identified RSK1 as a kinase that directly phosphorylates TRIM28 at S473, and, as such, RSK1 drives the TRIM28/E2F1 feedback loop. Accordingly, pS473-TRIM28 promotes CRPC progression, which is mitigated by RSK inhibition. In summary, our study reveals a critical role of the RSK1–TRIM28–E2F1 axis in CRPC progression, which may be exploited as a vulnerability in treating Rb-deficient CRPC.
Authors
Miyeong Kim, Jinpeng Liu, Yanquan Zhang, Ruixin Wang, Ryan Goettl, Jennifer Grasso, Derek B. Allison, Chi Wang, Tianyan Gao, Xiaoqi Liu, Ka-Wing Fong
Abstract
Colorectal cancer (CRC) is characterized by an immune-suppressive microenvironment that contributes to tumor progression and immunotherapy resistance. The gut microbiome produces diverse metabolites that feature unique mechanisms of interaction with host targets, yet the role of many metabolites in CRC remains poorly understood. In this study, the microbial metabolite 4-hydroxybenzeneacetic acid (4-HPA) promoted the infiltration of PMN myeloid-derived suppressor cells (PMN-MDSCs) in the tumor microenvironment, consequently inhibiting the antitumor response of CD8+ T cells and promoting CRC progression in vivo. Mechanistically, 4-HPA activates the JAK2/STAT3 pathway, which upregulates CXCL3 transcription, thereby recruiting PMN-MDSCs to the CRC microenvironment. Selective knockdown of CXCL3 resensitized tumors to anti-PD-1 immunotherapy in vivo. Chlorogenic acid reduces the production of 4-HPA by microbiota, likewise abolishing 4-HPA–mediated immunosuppression. The 4-HPA content in CRC tissues was notably increased in patients with advanced CRC. Overall, the gut microbiome uses 4-HPA as a messenger to control chemokine-dependent accumulation of PMN-MDSC cells and regulate antitumor immunity in CRC. Our findings provide a scientific basis for establishing clinical intervention strategies to reverse the tumor immune microenvironment and improve the efficacy of immunotherapy by reducing the interaction among intestinal microbiota, tumor cells, and tumor immune cells.
Authors
Qing Liao, Ximing Zhou, Ling Wu, Yuyi Yang, Xiaohui Zhu, Hangyu Liao, Yujie Zhang, Weidong Lian, Feifei Zhang, Hui Wang, Yanqing Ding, Liang Zhao
Abstract
Hyaluronan (HA) in the extracellular matrix promotes epithelial-mesenchymal transition (EMT) and metastasis; however, the mechanism by which the HA network constructed by cancer cells regulates cancer progression and metastasis in the tumor microenvironment (TME) remains largely unknown. In this study, inter-α-trypsin inhibitor heavy chain 2 (ITIH2), an HA-binding protein, was confirmed to be secreted from mesenchymal-like lung cancer cells when cocultured with cancer-associated fibroblasts. ITIH2 expression is transcriptionally upregulated by the EMT-inducing transcription factor ZEB1, along with HA synthase 2 (HAS2), which positively correlates with ZEB1 expression. Depletion of ITIH2 and HAS2 reduced HA matrix formation and the migration and invasion of lung cancer cells. Furthermore, ZEB1 facilitates alternative splicing and isoform expression of CD44, an HA receptor, and CD44 knockdown suppresses the motility and invasiveness of lung cancer cells. Using a deep learning–based drug-target interaction algorithm, we identified an ITIH2 inhibitor (sincalide) that inhibited HA matrix formation and migration of lung cancer cells, preventing metastatic colonization of lung cancer cells in mouse models. These findings suggest that ZEB1 remodels the HA network in the TME through the regulation of ITIH2, HAS2, and CD44, presenting a strategy for targeting this network to suppress lung cancer progression.
Authors
Sieun Lee, Jihye Park, Seongran Cho, Eun Ju Kim, Seonyeong Oh, Younseo Lee, Sungsoo Park, Keunsoo Kang, Dong Hoon Shin, Song Yi Ko, Jonathan M. Kurie, Young-Ho Ahn
Abstract
Maladaptive fear generalization is one of the hallmarks of trauma-related disorders. The endocannabinoid 2-arachidonoylglycerol (2-AG) is crucial for modulating anxiety, fear, and stress adaptation, but its role in balancing fear discrimination versus generalization is not known. To address this, we used a combination of plasma endocannabinoid measurement and neuroimaging in a childhood maltreatment–exposed and –nonexposed mixed population, combined with human and rodent fear-conditioning models. Here we show that 2-AG levels were inversely associated with fear generalization at the behavioral level in both mice and humans. In mice, 2-AG depletion increased the proportion of neurons that respond to, and the similarity of neuronal representations for, both threat-predictive and neutral stimuli within prelimbic prefrontal cortex neuronal ensembles. In humans, increased dorsolateral prefrontal cortical–amygdala resting-state connectivity was inversely correlated with fear generalization. These data provide convergent cross-species evidence that 2-AG is a key regulator of fear generalization and further support the notion that 2-AG deficiency could represent a trauma-related disorder-susceptibility endophenotype.
Authors
Luis E. Rosas-Vidal, Saptarnab Naskar, Leah M. Mayo, Irene Perini, Rameen Masroor, Megan Altemus, Liorimar Ramos-Medina, S. Danyal Zaidi, Hilda Engelbrektsson, Puja Jagasia, Markus Heilig, Sachin Patel
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