The agonistic/antagonistic biocharacter of selective estrogen receptor modulators (SERMs) can have therapeutic advantages, particularly in the case of premenopausal breast cancers. Although the contradictory effects of these modulators have been studied in terms of crosstalk between the estrogen receptor α (ER) and coactivator dynamics and growth factor signaling, the molecular basis of these mechanisms is still obscure. We identify a series of regulatory mechanisms controlling cofactor dynamics on ER and SERM function, whose activities require F-box protein 22 (Fbxo22). Skp1, Cullin1, F-box–containing complex (SCFFbxo22) ubiquitylated lysine demethylase 4B (KDM4B) complexed with tamoxifen-bound (TAM-bound) ER, whose degradation released steroid receptor coactivator (SRC) from ER. Depletion of Fbxo22 resulted in ER-dependent transcriptional activation via transactivation function 1 (AF1) function, even in the presence of SERMs. In living cells, TAM released SRC and KDM4B from ER in a Fbxo22-dependent manner. SRC release by TAM required Fbxo22 on almost all ER-SRC–bound enhancers and promoters. TAM failed to prevent the growth of Fbxo22-depleted, ER-positive breast cancers both in vitro and in vivo. Clinically, a low level of Fbxo22 in tumor tissues predicted a poorer outcome in ER-positive/human epidermal growth factor receptor type 2–negative (HER2-negative) breast cancers with high hazard ratios, independently of other markers such as Ki-67 and node status. We propose that the level of Fbxo22 in tumor tissues defines a new subclass of ER-positive breast cancers for which SCFFbxo22-mediated KDM4B degradation in patients can be a therapeutic target for the next generation of SERMs.
Yoshikazu Johmura, Ichiro Maeda, Narumi Suzuki, Wenwen Wu, Atsushi Goda, Mariko Morita, Kiyoshi Yamaguchi, Mizuki Yamamoto, Satoi Nagasawa, Yasuyuki Kojima, Koichiro Tsugawa, Natsuko Inoue, Yasuo Miyoshi, Tomo Osako, Futoshi Akiyama, Reo Maruyama, Jun-ichiro Inoue, Yoichi Furukawa, Tomohiko Ohta, Makoto Nakanishi
The pathogenesis of ischemic diseases remains unclear. Here we demonstrate the induction of microRNA-668 (miR-668) in ischemic acute kidney injury (AKI) in human patients, mice, and renal tubular cells. The induction was HIF-1 dependent, as HIF-1 deficiency in cells and kidney proximal tubules attenuated miR-668 expression. We further identified a functional HIF-1 binding site in the miR-668 gene promoter. Anti–miR-668 increased apoptosis in renal tubular cells and enhanced ischemic AKI in mice, whereas miR-668 mimic was protective. Mechanistically, anti–miR-668 induced mitochondrial fragmentation, whereas miR-668 blocked mitochondrial fragmentation during hypoxia. We analyzed miR-668 target genes through immunoprecipitation of microRNA-induced silencing complexes followed by RNA deep sequencing and identified 124 protein-coding genes as likely targets of miR-668. Among these genes, only mitochondrial protein 18 kDa (MTP18) has been implicated in mitochondrial dynamics. In renal cells and mouse kidneys, miR-668 mimic suppressed MTP18, whereas anti–miR-668 increased MTP18 expression. Luciferase microRNA target reporter assay further verified MTP18 as a direct target of miR-668. In renal tubular cells, knockdown of MTP18 suppressed mitochondrial fragmentation and apoptosis. Together, the results suggest that miR-668 is induced via HIF-1 in ischemic AKI and that, upon induction, miR-668 represses MTP18 to preserve mitochondrial dynamics for renal tubular cell survival and kidney protection.
Qingqing Wei, Haipeng Sun, Shuwei Song, Yong Liu, Pengyuan Liu, Man Jiang Livingston, Jianwen Wang, Mingyu Liang, Qing-Sheng Mi, Yuqing Huo, Norris Stanley Nahman, Changlin Mei, Zheng Dong
Activating mutations in the Wnt pathway drive a variety of cancers, but the specific targets and pathways activated by Wnt ligands are not fully understood. To bridge this knowledge gap, we performed a comprehensive time-course analysis of Wnt-dependent signaling pathways in an orthotopic model of Wnt-addicted pancreatic cancer, using a porcupine (PORCN) inhibitor currently in clinical trials, and validated key results in additional Wnt-addicted models. The temporal analysis of the drug-perturbed transcriptome demonstrated direct and indirect regulation of more than 3,500 Wnt-activated genes (23% of the transcriptome). Regulation was both via Wnt/β-catenin and through the modulation of protein abundance of important transcription factors, including MYC, via Wnt-dependent stabilization of proteins (Wnt/STOP). Our study identifies a central role of Wnt/β-catenin and Wnt/STOP signaling in controlling ribosome biogenesis, a key driver of cancer proliferation.
Babita Madan, Nathan Harmston, Gahyathiri Nallan, Alex Montoya, Peter Faull, Enrico Petretto, David M. Virshup
βIV-Spectrin, along with ankyrin and Ca2+/calmodulin-dependent kinase II (CaMKII), has been shown to form local signaling domains at the intercalated disc, while playing a key role in the regulation of Na+ and K+ channels in cardiomyocytes. In this issue of the JCI, Unudurthi et al. show that under chronic pressure overload conditions, CaMKII activation leads to βIV-spectrin degradation, resulting in the release of sequestered STAT3 from the intercalated discs. This in turn leads to dysregulation of STAT3-mediated gene transcription, maladaptive remodeling, fibrosis, and decreased cardiac function. Overall, this study presents interesting findings regarding the role of CaMKII and βIV-spectrin under physiological as well as pathological conditions.
Mohit Hulsurkar, Ann P. Quick, Xander H.T. Wehrens
People with diabetes mellitus are at higher risk of developing serious ascending infections of the urinary tract. The traditional explanation has focused on the role of glycosuria in promoting bacterial growth. Using mouse models, Murtha et al. demonstrate that when the intracellular insulin signaling pathway is compromised, antimicrobial defenses are compromised too, and the mice are unable to effectively handle uropathogenic E. coli introduced experimentally into the urinary tract. These observations strongly support the hypothesis that the antimicrobial defenses of the kidney are dependent on insulin, and the urinary tract infections associated with diabetes occur due to reduced expression of these key effectors of innate immunity.
Ischemia-reperfusion (I/R) sets off a devastating cascade of events, leading to cell death and possible organ failure. Treatments to limit I/R-associated damage are lacking, and the pathways that drive injury are poorly understood. In this issue of the JCI, Wei and colleagues identify microRNA-668 (miR-668) as a protective factor in acute kidney injury (AKI). miR-668 was shown to repress mitochondrial fission–associated protein MTP18, thereby inhibiting pathogenic mitochondrial fragmentation. In murine models of I/R-induced AKI, treatment with a miR-668 mimetic reduced mitochondrial fragmentation and improved renal function. Moreover, HIF-1α was shown to be required for miR-688 expression in response to I/R. Importantly, Wei et al. show miR-668 upregulation in a cohort of human patients with AKI. Together, these results identify a HIF-1α/miR-668/MTP18 axis that may have potential as a therapeutic target for AKI.
Nicholas Chun, Steven G. Coca, John Cijiang He
Mutations in CNGA3 and CNGB3, the genes encoding the subunits of the tetrameric cone photoreceptor cyclic nucleotide–gated ion channel, cause achromatopsia, a congenital retinal disorder characterized by loss of cone function. However, a small number of patients carrying the CNGB3/c.1208G>A;p.R403Q mutation present with a variable retinal phenotype ranging from complete and incomplete achromatopsia to moderate cone dysfunction or progressive cone dystrophy. By exploring a large patient cohort and published cases, we identified 16 unrelated individuals who were homozygous or (compound-)heterozygous for the CNGB3/c.1208G>A;p.R403Q mutation. In-depth genetic and clinical analysis revealed a co-occurrence of a mutant CNGA3 allele in a high proportion of these patients (10 of 16), likely contributing to the disease phenotype. To verify these findings, we generated a Cngb3R403Q/R403Q mouse model, which was crossbred with Cnga3-deficient (Cnga3–/–) mice to obtain triallelic Cnga3+/– Cngb3R403Q/R403Q mutants. As in human subjects, there was a striking genotype-phenotype correlation, since the presence of 1 Cnga3-null allele exacerbated the cone dystrophy phenotype in Cngb3R403Q/R403Q mice. These findings strongly suggest a digenic and triallelic inheritance pattern in a subset of patients with achromatopsia/severe cone dystrophy linked to the CNGB3/p.R403Q mutation, with important implications for diagnosis, prognosis, and genetic counseling.
Markus Burkard, Susanne Kohl, Timm Krätzig, Naoyuki Tanimoto, Christina Brennenstuhl, Anne E. Bausch, Katrin Junger, Peggy Reuter, Vithiyanjali Sothilingam, Susanne C. Beck, Gesine Huber, Xi-Qin Ding, Anja K. Mayer, Britta Baumann, Nicole Weisschuh, Ditta Zobor, Gesa-Astrid Hahn, Ulrich Kellner, Sascha Venturelli, Elvir Becirovic, Peter Charbel Issa, Robert K. Koenekoop, Günther Rudolph, John Heckenlively, Paul Sieving, Richard G. Weleber, Christian Hamel, Xiangang Zong, Martin Biel, Robert Lukowski, Matthias W. Seeliger, Stylianos Michalakis, Bernd Wissinger, Peter Ruth
Notch signaling critically controls cell fate decisions in mammals, both during embryogenesis and in adults. In the skeleton, Notch suppresses osteoblast differentiation and sustains bone marrow mesenchymal progenitors during postnatal life. Stabilizing mutations of Notch2 cause Hajdu-Cheney syndrome, which is characterized by early-onset osteoporosis in humans, but the mechanism whereby Notch inhibits bone accretion is not fully understood. Here, we report that activation of Notch signaling by either Jagged1 or the Notch2 intracellular domain suppresses glucose metabolism and osteoblast differentiation in primary cultures of bone marrow mesenchymal progenitors. Importantly, deletion of Notch2 in the limb mesenchyme increases both glycolysis and bone formation in the long bones of postnatal mice, whereas pharmacological reduction of glycolysis abrogates excessive bone formation. Mechanistically, Notch reduces the expression of glycolytic and mitochondrial complex I genes, resulting in a decrease in mitochondrial respiration, superoxide production, and AMPK activity. Forced activation of AMPK restores glycolysis in the face of Notch signaling. Thus, suppression of glucose metabolism contributes to the mechanism, whereby Notch restricts osteoblastogenesis from bone marrow mesenchymal progenitors.
Seung-Yon Lee, Fanxin Long
Nonalcoholic fatty liver disease (NAFLD) arises from mitochondrial dysfunction under sustained imbalance between energy intake and expenditure, but the underlying mechanisms controlling mitochondrial respiration have not been entirely understood. Heterotrimeric G proteins converge with activated GPCRs to modulate cell-signaling pathways to maintain metabolic homeostasis. Here, we investigated the regulatory role of G protein α12 (Gα12) on hepatic lipid metabolism and whole-body energy expenditure in mice. Fasting increased Gα12 levels in mouse liver. Gα12 ablation markedly augmented fasting-induced hepatic fat accumulation. cDNA microarray analysis from Gna12-KO liver revealed that the Gα12-signaling pathway regulated sirtuin 1 (SIRT1) and PPARα, which are responsible for mitochondrial respiration. Defective induction of SIRT1 upon fasting was observed in the liver of Gna12-KO mice, which was reversed by lentivirus-mediated Gα12 overexpression in hepatocytes. Mechanistically, Gα12 stabilized SIRT1 protein through transcriptional induction of ubiquitin-specific peptidase 22 (USP22) via HIF-1α increase. Gα12 levels were markedly diminished in liver biopsies from NAFLD patients. Consistently, Gna12-KO mice fed a high-fat diet displayed greater susceptibility to diet-induced liver steatosis and obesity due to decrease in energy expenditure. Our results demonstrate that Gα12 regulates SIRT1-dependent mitochondrial respiration through HIF-1α–dependent USP22 induction, identifying Gα12 as an upstream molecule that contributes to the regulation of mitochondrial energy expenditure.
Tae Hyun Kim, Yoon Mee Yang, Chang Yeob Han, Ja Hyun Koo, Hyunhee Oh, Su Sung Kim, Byoung Hoon You, Young Hee Choi, Tae-Sik Park, Chang Ho Lee, Hitoshi Kurose, Mazen Noureddin, Ekihiro Seki, Yu-Jui Yvonne Wan, Cheol Soo Choi, Sang Geon Kim
People with diabetes mellitus have increased infection risk. With diabetes, urinary tract infection (UTI) is more common and has worse outcomes. Here, we investigate how diabetes and insulin resistance impact the kidney’s innate defenses and urine sterility. We report that type 2 diabetic mice have increased UTI risk. Moreover, insulin-resistant prediabetic mice have increased UTI susceptibility, independent of hyperglycemia or glucosuria. To identify how insulin resistance affects renal antimicrobial defenses, we genetically deleted the insulin receptor in the kidney’s collecting tubules and intercalated cells. Intercalated cells, located within collecting tubules, contribute to epithelial defenses by acidifying the urine and secreting antimicrobial peptides (AMPs) into the urinary stream. Collecting duct and intercalated cell–specific insulin receptor deletion did not impact urine acidification, suppressed downstream insulin-mediated targets and AMP expression, and increased UTI susceptibility. Specifically, insulin receptor–mediated signaling regulates AMPs, including lipocalin 2 and ribonuclease 4, via phosphatidylinositol-3-kinase signaling. These data suggest that insulin signaling plays a critical role in renal antibacterial defenses.
Matthew J. Murtha, Tad Eichler, Kristin Bender, Jackie Metheny, Birong Li, Andrew L. Schwaderer, Claudia Mosquera, Cindy James, Laura Schwartz, Brian Becknell, John David Spencer
Heart failure (HF) remains a major source of morbidity and mortality in the US. The multifunctional Ca2+/calmodulin-dependent kinase II (CaMKII) has emerged as a critical regulator of cardiac hypertrophy and failure, although the mechanisms remain unclear. Previous studies have established that the cytoskeletal protein βIV-spectrin coordinates local CaMKII signaling. Here, we sought to determine the role of a spectrin-CaMKII complex in maladaptive remodeling in HF. Chronic pressure overload (6 weeks of transaortic constriction [TAC]) induced a decrease in cardiac function in WT mice but not in animals expressing truncated βIV-spectrin lacking spectrin-CaMKII interaction (qv3J mice). Underlying the observed differences in function was an unexpected differential regulation of STAT3-related genes in qv3J TAC hearts. In vitro experiments demonstrated that βIV-spectrin serves as a target for CaMKII phosphorylation, which regulates its stability. Cardiac-specific βIV-spectrin–KO (βIV-cKO) mice showed STAT3 dysregulation, fibrosis, and decreased cardiac function at baseline, similar to what was observed with TAC in WT mice. STAT3 inhibition restored normal cardiac structure and function in βIV-cKO and WT TAC hearts. Our studies identify a spectrin-based complex essential for regulation of the cardiac response to chronic pressure overload. We anticipate that strategies targeting the new spectrin-based “statosome” will be effective at suppressing maladaptive remodeling in response to chronic stress.
Sathya D. Unudurthi, Drew Nassal, Amara Greer-Short, Nehal Patel, Taylor Howard, Xianyao Xu, Birce Onal, Tony Satroplus, Deborah Hong, Cemantha Lane, Alyssa Dalic, Sara N. Koenig, Adam C. Lehnig, Lisa A. Baer, Hassan Musa, Kristin I. Stanford, Sakima Smith, Peter J. Mohler, Thomas J. Hund
Macrophages perform key functions in tissue homeostasis that are influenced by the local tissue environment. Within the tumor microenvironment tumor associated macrophages can be altered to acquire properties that enhance tumor growth. Here, we found lactate, a metabolite found in high concentration within the anaerobic tumor environment, activated mTORC1 that subsequently suppressed TFEB-mediated expression of a macrophage-specific vacuolar ATPase subunit ATP6V0d2. Atp6v0d2-/- mice were more susceptible to tumor growth with enhanced HIF-2α-mediated VEGF production in macrophages that display a more protumoral phenotype. We found that ATP6V0d2 targeted HIF-2α but not HIF-1α for lysosome-mediated degradation. Blockade of HIF-2α transcriptional activity reversed the susceptibility of Atp6v0d2-/- mice to tumor development. Furthermore, in a cohort of patients with lung adenocarcinoma, expression of ATP6V0d2 and HIF-2α was positively and negatively correlated with survival respectively, suggesting a critical role of the macrophage lactate-ATP6V0d2-HIF-2α axis in maintaining tumor growth in human patients. Together, our results highlight the ability of tumor cells to modify the function of tumor-infiltrating macrophages to optimize the microenvironment for tumor growth.
Na Liu, Jing Luo, Dong Kuang, Sanpeng Xu, Yaqi Duan, Yu Xia, Zhengping Wei, Xiuxiu Xie, Bingjiao Yin, Fang Chen, Shunqun Luo, Huicheng Liu, Jing Wang, Kan Jiang, Feili Gong, Zhao-hui Tang, Xiang Cheng, Huabin Li, Zhuoya Li, Arian Laurence, Guoping Wang, Xiang-Ping Yang
Ca2+ channel β-subunit interactions with pore-forming α-subunits are long-thought to be obligatory for channel trafficking to the cell surface and for tuning of basal biophysical properties in many tissues. Unexpectedly, we demonstrate that transgenic expression of mutant cardiac α1C subunits lacking capacity to bind CaVβ because of alanine-substitutions of three conserved residues — Y467, W470, and I471 in the α-interaction domain of rabbit α1C — can traffic to the sarcolemma in adult cardiomyocytes in vivo and sustain normal excitation-contraction coupling. However, these β-less Ca2+ channels cannot be stimulated by β-adrenergic pathway agonists, and thus adrenergic-augmentation of contractility is markedly impaired in isolated cardiomyocytes and in hearts. Similarly, viral-mediated expression of a β-subunit-sequestering-peptide sharply curtailed β-adrenergic stimulation of wild-type Ca2+ channels, identifying an approach to specifically modulate β-adrenergic regulation of cardiac contractility. Our data demonstrate that β subunits are required for β-adrenergic regulation of CaV1.2 channels and positive inotropy in the heart, but are dispensable for CaV1.2 trafficking to the adult cardiomyocyte cell surface, and for basal function and excitation-contraction coupling.
Lin Yang, Alexander Katchman, Jared S. Kushner, Alexander Kushnir, Sergey I. Zakharov, Bi-xing Chen, Zunaira Shuja, Prakash Subramanyam, Guoxia Liu, Arianne Papa, Daniel D. Roybal, Geoffrey S. Pitt, Henry M. Colecraft, Steven O. Marx
Current thalassemia gene therapy protocols require the collection of hematopoietic stem/progenitor cells (HSPCs), in vitro culture, lentivirus vector transduction, and retransplantation into myelo-ablated patients. Because of cost and technical complexity, it is unlikely that such protocols will be applicable in developing countries where the greatest demand for a beta-thalassemia therapy lies. We have developed a simple in vivo HSPC gene therapy approach that involved HSPC mobilization and an intravenous injection of integrating HDAd5/35++ vectors. Transduced HSPCs homed back to the bone marrow where they persisted long-term. HDAd5/35++ vectors for in vivo gene therapy of thalassemia had a unique capsid that targeted primitive HSPCs through human CD46, a relatively safe SB100X transposase-based integration machinery, a micro-LCR driven gamma-globin gene and, a MGMT(P140K) system that allowed for increasing the therapeutic effect by short-term treatment with low-dose O6BG/BCNU. We showed in “healthy” human CD46 transgenic mice and in a mouse model of thalassemia intermedia that our in vivo approach resulted in stable gamma-globin expression in the majority of circulating red blood cells. The high marking frequency was maintained in secondary recipients. In the thalassemia model, a near complete phenotypic correction was achieved. The treatment was well tolerated. This cost-efficient and “portable” approach could permit a broader clinical application of thalassemia gene therapy.
Hongjie Wang, Aphrodite Georgakopoulou, Nikoletta Psatha, Chang Li, Chrysi Capsali, Himanshu Bhusan Samal, Achilles Anagnostopoulos, Anja Ehrhardt, Zsuzsanna Izsvák, Thalia Papayannopoulou, Evangelia Yannaki, André Lieber
Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disorder characterized by accelerated cardiovascular disease with extensive fibrosis. It is caused by a mutation in LMNA leading to expression of truncated prelamin A (progerin) in the nucleus. To investigate the contribution of the endothelium to cardiovascular HGPS pathology, we generated an endothelium-specific HGPS mouse model with selective endothelial progerin expression. Transgenic mice develop interstitial myocardial and perivascular fibrosis and left ventricular hypertrophy associated with diastolic dysfunction and premature death. Endothelial cells show impaired shear stress response and reduced levels of endothelial nitric oxide synthase (eNOS) and NO. On the molecular level, progerin impairs nucleocytoskeletal coupling in endothelial cells through changes in mechanoresponsive components at the nuclear envelope, increased F-/G-actin ratios and deregulation of mechanoresponsive myocardin-related transcription factor-A (MRTFA). MRTFA binds to the Nos3 promoter reducing eNOS expression, thereby mediating a pro-fibrotic paracrine response in fibroblasts. MRTFA inhibition rescues eNOS levels and ameliorates the pro-fibrotic effect of endothelial cells in vitro. Although this murine model lacks the key anatomical feature of vascular smooth muscle cell loss seen in HGPS patients, our data show that progerin-induced impairment of mechanosignaling in endothelial cells contributes to excessive fibrosis and cardiovascular disease in HGPS patients.
Selma Osmanagic-Myers, Attila Kiss, Christina Manakanatas, Ouafa Hamza, Franziska Sedlmayer, Petra L. Szabo, Irmgard Fischer, Petra Fichtinger, Bruno K. Podesser, Maria Eriksson, Roland Foisner
Despite showing success in treating melanoma and haematological malignancies, adoptive cell therapy (ACT) has generated only limited effects in solid tumors. This is, in part, due to a lack of specific antigen targets, poor trafficking/infiltration and immunosuppression in the tumor microenvironment. In this study, we combined ACT with oncolytic virus vaccines (OVV) to drive expansion and tumor infiltration of transferred antigen-specific T cells, and demonstrated that the combination is highly potent for the eradication of established solid tumors. Consistent with other successful immunotherapies, this approach elicited severe autoimmune consequence when the antigen targeted was a self-protein. However, modulation of IFNα/β signaling, either by functional blockade or rational choice of an OVV backbone, ameliorated autoimmune side effects without compromising antitumor efficacy. Our study uncovers a pathogenic role for IFNα/β in facilitating autoimmune toxicity during cancer immunotherapy and offers a safe and powerful combinatorial regimen with immediate translational applications.
Scott R. Walsh, Donald Bastin, Lan Chen, Andrew Nguyen, Christopher J. Storbeck, Charles Lefebvre, David Stojdl, Jonathan L. Bramson, John C. Bell, Yonghong Wan
In this issue of the JCI, Lee et al. expose the antagonistic role of the vascular growth factor angiopoietin-2 in heart repair. Elevated expression of angiopoetin-2 in the infarct border zone exacerbated vascular leakage, hypoxia, and fibrosis by interfering in endothelium-stabilizing angiopoetin-1/Tie2 signaling. Angiopoietin-2 blockade mitigated pathological cardiac remodeling, supporting its potential as a therapeutic target in heart failure. This issue’s cover illustrates the low level of cardiac fibrosis (green) observed in the infarcted murine heart in the absence of angiopoietin-2 expression. Image credit: Seung-Jun Lee.
JCI This Month is a digest of the research, reviews, and other features published each month.
Mitochondria transform nutrients and oxygen into chemical energy that powers a multitude of cellular functions. While mitochondrial aerobic glycolysis generates the majority of a cell’s ATP, its byproducts also have wide-ranging influences on cellular health and longevity. This review series, edited by Dr. Michael Sack, focuses on the many contributions of mitochondria to disease and aging. The reviews highlight evidence linking altered mitochondrial metabolism and oxidative stress to a range of pathophysiological phenomena: inflammation and immune dysfunction, heart failure, cancer development, metabolic disease, and more. In many diseases and conditions, mitochondrial dysfunction is considered the tipping point toward pathological progression. However, as these reviews discuss, therapeutic targeting of mitochondria may be a powerful strategy to subvert disease and aging processes.