Non-alcoholic 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 signals from activated GPCRs, and modulate cell signaling pathways to maintain metabolic homeostasis. Here, we investigated the regulatory role of Gα12 on hepatic lipid metabolism and whole-body energy expenditure in mice. Fasting increased Gα12 level in mouse liver. Gα12 ablation markedly augmented fasting-induced hepatic fat accumulation. cDNA microarray analysis from Gna12 KO liver revealed that Gα12 signaling pathway regulated sirtuin 1 (SIRT1) and PPARα 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 USP22 via HIF-1α increase. Gα12 levels were markedly diminished in liver biopsies from NAFLD patients. Consistently, Gna12 KO mice fed 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
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 the Hajdu-Cheney syndrome 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 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 the excessive bone formation. Mechanistically, Notch reduces the expression of glycolytic and mitochondrial Complex I genes, resulting in a decease 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
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
Chronic lymphocytic leukemia (CLL) is characterized by clonal proliferation and progressive accumulation of mature, B lymphocytes in the peripheral blood, lymphoid tissues and bone marrow. CLL is characterized by profound immune defects, leading to severe infectious complications. T cells are numerically, phenotypically, and functionally highly abnormal in CLL, with only limited ability to exert antitumor immune responses. Exhaustion of T cells has also been implicated as playing an important role in anti-tumor responses. The CLL-mediated T cell exhaustion is achieved by aberrant expression of several inhibitory molecules on CLL and their environment, prominently the PD-L1/PD-1 receptors. Previously, we showed that CD84, a member of the SLAM family of receptors, bridges between CLL cells and their microenvironment. In the current study, we followed CD84 regulation of T cell function. We showed that a cell-cell interaction mediated through human and mouse CD84 upregulates PDL1 expression on CLL and their microenvironment, and PD1 expression on T cells. This resulted in suppression of T cell response and activity in vitro and in vivo. Thus, our results demonstrated a role for CD84 in regulation of immune checkpoints by leukemia cells, and suggested CD84 blockade as a therapeutic strategy to reverse tumor-induced immune suppression.
Hadas Lewinsky, Avital F. Barak, Victoria Huber, Matthias P. Kramer, Lihi Radomir, Lital Sever, Irit Orr, Vita Mirkin, Nili Dezorella, Mika Shapiro, Yosef Cohen, Lev Shvidel, Martina Seiffert, Yair Herishanu, Shirly Becker-Herman, Idit Shachar
The accrual of myeloid-derived suppressor cells (MDSCs) represents a major obstacle to effective immunotherapy in cancer patients, but the mechanisms underlying this process in the human setting remain elusive. Here, we describe a set of microRNAs (miR-146a, miR-155, miR-125b, miR-100, let-7e, miR-125a, miR-146b, miR-99b) that are associated with MDSCs and with resistance to treatment with immune checkpoint inhibitors in melanoma patients. The miRs were identified by transcriptional analyses as being responsible for the conversion of monocytes into MDSCs (CD14+HLA-DRneg cells) mediated by melanoma extracellular vesicles (EVs) and were shown to recreate MDSC features upon transfection. In melanoma patients, these miRs are increased in circulating CD14+ monocytes, plasma and tumor samples, where they correlate with the myeloid cell infiltrate. In plasma, their baseline level clusters with the clinical efficacy of CTLA-4 or PD-1 blockade. Hence, MDSC-related miRs represent an indicator of MDSC activity in cancer patients and a potential blood marker of a poor immunotherapy outcome.
Veronica Huber, Viviana Vallacchi, Viktor Fleming, Xiaoying Hu, Agata Cova, Matteo Dugo, Eriomina Shahaj, Roberta Sulsenti, Elisabetta Vergani, Paola Filipazzi, Angela De Laurentiis, Luca Lalli, Lorenza Di Guardo, Roberto Patuzzo, Barbara Vergani, Elena Casiraghi, Mara Cossa, Ambra Gualeni, Valentina Bollati, Flavio Arienti, Filippo De Braud, Luigi Mariani, Antonello Villa, Peter Altevogt, Viktor Umansky, Monica Rodolfo, Licia Rivoltini
Concordant activation of MYC and BCL-2 oncoproteins in double-hit lymphoma (DHL) results in aggressive disease that is refractory to treatment. By integrating activity-based proteomic profiling and drug screens, polo-like kinase-1 (PLK1) was identified as an essential regulator of the MYC-dependent kinome in DHL. Notably, PLK1 was expressed at high levels in DHL, correlated with MYC expression and connoted poor outcome. Further, PLK1 signaling augmented MYC protein stability and, in turn, MYC directly induced PLK1 transcription, establishing a feed-forward MYC-PLK1 circuit in DHL. Finally, inhibition of PLK1 triggered degradation of MYC and of the anti-apoptotic protein MCL1, and PLK1 inhibitors showed synergy with BCL-2 antagonists in blocking DHL cell growth, survival and tumorigenicity, supporting clinical targeting of PLK1 in DHL.
Yuan Ren, Chengfeng Bi, Xiaohong Zhao, Tint Lwin, Cheng Wang, Ji Yuan, Ariosto S. Silva, Bijal D. Shah, Bin Fang, Tao Li, John M. Koomen, Huijuan Jiang, Julio C. Chavez, Lan Pham, Praneeth R. Sudalagunta, Lixin Wan, Xuefeng Wang, William S. Dalton, Lynn C. Moscinski, Kenneth H. Shain, Julie Vose, John L. Cleveland, Eduardo M. Sotomayor, Kai Fu, Jianguo Tao
BACKGROUND. Chronic obstructive pulmonary disease (COPD) is characterized by airway remodeling. Characterization of airway changes on computed tomography has been challenging due to the complexity of the recurring branching patterns, and this can be better measured using fractal dimensions. METHODS. We analyzed segmented airway trees of 8135 participants enrolled in the COPDGene cohort. The fractal complexity of the segmented airway tree was measured by the Airway Fractal Dimension (AFD) using the Minkowski-Bouligand box-counting dimension. We examined associations between AFD and lung function and respiratory morbidity using multivariable regression analyses. We further estimated the extent of peribronchial emphysema (%) within 5mm of the airway tree as this is likely to affect AFD. We classified participants into 4 groups based on median AFD and %peribronchial emphysema, and estimated survival. RESULTS. AFD was significantly associated with FEV1 (p<0.001) and FEV1/FVC (p<0.001) after adjusting for age, race, gender, smoking status, pack-years of smoking, body-mass-index, CT emphysema, air trapping, airway thickness, and CT scanner type. On multivariable analysis, AFD was also associated with respiratory-quality of life and six-minute walk distance, as well as exacerbations, lung function decline and mortality on longitudinal follow-up. We identified a subset of participants with AFDmedian who had worse survival compared with participants with high AFD and low peribronchial emphysema (adjusted HR = 2.72, 95%CI 2.20 to 3.35; p<0.001), a substantial number of whom were not identified by traditional spirometry severity grades. CONCLUSIONS. Airway fractal dimension as a measure of airway branching complexity and remodeling in smokers is associated with respiratory morbidity and lung function change, offers prognostic information additional to traditional CT measures of airway wall thickness, and can be used to estimate mortality risk.
Sandeep Bodduluri, Abhilash S. Kizhakke Puliyakote, Sarah E. Gerard, Joseph M. Reinhardt, Eric A. Hoffman, John D. Newell Jr., Hrudaya P. Nath, MeiLan K. Han, George R. Washko, Raúl San José Estépar, Mark T. Dransfield, Surya P. Bhatt
MASTL, a Ser/Thr kinase that inhibits PP2A-B55 complexes during mitosis, is mutated in autosomal dominant thrombocytopenia. However, the connections between the cell cycle machinery and this human disease remain unexplored. We report here that, whereas Mastl ablation in megakaryocytes prevented proper maturation of these cells, mice carrying the thrombocytopenia-associated mutation developed thrombocytopenia as a consequence of aberrant activation and survival of platelets. Activation of mutant platelets was characterized by hyper-stabilized pseudopods mimicking the effect of PP2A inhibition and actin polymerization defects. These aberrations were accompanied by abnormal hyper-phosphorylation of multiple components of the actin cytoskeleton and were rescued both in vitro and in vivo by inhibiting upstream kinases such as PKA, PKC, or AMPK. These data reveal an unexpected role of Mastl in actin cytoskeleton dynamics in postmitotic cells, and suggest that the thrombocytopenia-associated mutation in MASTL is a pathogenic dominant mutation that mimics decreased PP2A activity resulting in altered phosphorylation of cytoskeletal regulatory pathways.
Begoña Hurtado, Marianna Trakala, Pilar Ximénez-Embún, Aicha El Bakkali, David Partida, Belén Sanz-Castillo, Mónica Álvarez-Fernández, María Maroto, Ruth Sánchez-Martínez, Lola Martínez, Javier Muñoz, Pablo García de Frutos, Marcos Malumbres
Acute Myeloid Leukemia and Myelodysplastic Syndromes are associated with disease-initiating stem cells that are not eliminated by conventional therapies. Transcriptomic analysis of stem and progenitor populations in MDS and AML demonstrated overexpression of STAT3 that was validated in an independent cohort. STAT3 overexpression was predictive of a shorter survival and worse clinical features in a large MDS cohort. High STAT3 expression signature in MDS CD34+ cells was similar to known pre-leukemic gene signatures. Functionally, STAT3 inhibition by a clinical, antisense oligonucleotide, AZD9150, led to reduced viability and increased apoptosis in leukemic cell lines. AZD9150 was rapidly incorporated by primary MDS/AML stem and progenitor cells and led to increased hematopoietic differentiation. STAT3 knockdown also impaired leukemic growth in vivo and led to decreased expression of MCL1 and other oncogenic genes in malignant cells. These studies demonstrate that STAT3 is an adverse prognostic factor in MDS/AML and provide a pre-clinical rationale for studies using AZD9150 in these diseases.
Aditi Shastri, Gaurav Choudhary, Margarida Teixeira, Shanisha Gordon-Mitchell, Nandini Ramachandra, Lumie Bernard, Sanchari Bhattacharyya, Robert Lopez, Kith Pradhan, Orsolya Giricz, Goutham Ravipati, Li-Fan Wong, Sally Cole, Tushar D. Bhagat, Jonathan Feld, Yosman Dhar, Matthias Bartenstein, Victor J. Thiruthuvanathan, Amittha Wickrema, B. Hilda Ye, David A. Frank, Andrea Pellagatti, Jacqueline Boultwood, Tianyuan Zhou, Youngsoo Kim, A. Robert MacLeod, Pearlie K. Epling-Burnette, Minwei Ye, Patricia McCoon, Richard Woessner, Ulrich Steidl, Britta Will, Amit K. Verma
Obesity is a major risk factor for developing nonalcoholic fatty-liver disease (NAFLD). NAFLD is the most common form of chronic liver disease and closely associated with insulin resistance, ultimately leading to cirrhosis and hepatocellular carcinoma. However, knowledge of the intracellular regulators of obesity-linked fatty-liver disease remains incomplete. Here we showed that hepatic Rho-kinase 1 (ROCK1) drives obesity-induced steatosis in mice through stimulation of de novo lipogenesis. Mice lacking ROCK1 in the liver were resistant to diet-induced obesity due to increased energy expenditure and thermogenic gene expression. Constitutive expression of hepatic ROCK1 was sufficient to promote adiposity, insulin resistance, and hepatic lipid accumulation in mice fed a high-fat diet. Correspondingly, liver-specific ROCK1 deletion prevented the development of severe hepatic steatosis and reduced hyperglycemia in obese diabetic (ob/ob) mice. Of pathophysiologic significance, hepatic ROCK1 was markedly up-regulated in humans with fatty-liver disease and correlated with risk factors clustering around NAFLD and insulin resistance. Mechanistically, we found that hepatic ROCK1 suppresses AMPK activity and a ROCK1-AMPK pathway is necessary to mediate cannabinoid-induced lipogenesis in the liver. Furthermore, treatment with metformin, the most widely used anti-diabetes drug, reduced hepatic lipid accumulation by inactivating ROCK1, resulting in activation of AMPK downstream signaling. Taken together, our findings establish a ROCK1-AMPK signaling axis that regulates de novo lipogenesis, providing a unique target for treating obesity-related metabolic disorders such as NAFLD.
Hu Huang, Seung-Hwan Lee, Inês Sousa-Lima, Sang Soo Kim, Won Min Hwang, Yossi Dagon, Won-Mo Yang, Sungman Cho, Min-Cheol Kang, Ji A Seo, Munehiko Shibata, Hyunsoo Cho, Getachew Debas Belew, Jinhyuk Bhin, Bhavna N. Desai, Min Jeong Ryu, Minho Shong, Peixin Li, Hua Meng, Byung-Hong Chung, Daehee Hwang, Min Seon Kim, Kyong Soo Park, Paula Macedo, Morris White, John Jones, Young-Bum Kim
Sugar- and lipid-derived aldehydes are reactive carbonyl species (RCS) frequently used as surrogate markers of oxidative stress in obesity. A pathogenic role for RCS in metabolic diseases of obesity remains controversial, however, due in part to their highly diffuse and broad reactivity, and to lack of specific RCS-scavenging therapies. Naturally occurring histidine dipeptides (e.g., anserine and carnosine) possess RCS reactivity, but their therapeutic potential in humans is limited by serum carnosinases. Here we present the rational design, characterization and pharmacological evaluation of ‘carnosinol’ (i.e. (2S)-2-(3-amino propanoylamino)-3-(1H-imidazol-5-yl)propanol) a derivative of carnosine with high oral bioavailability that is resistant to carnosinases. Carnosinol displayed a suitable ADMET profile and was determined to have the greatest potency and selectivity toward α,β-unsaturated aldehydes (e.g. 4-hydroxynonenal, HNE, acrolein) among all others so far reported. In rodent models of diet-induced obesity and metabolic syndrome, carnosinol dose-dependently attenuated HNE-adduct formation in liver and skeletal muscle while simultaneously mitigating inflammation, dyslipidemia, insulin resistance, and steatohepatitis. These improvements in metabolic parameters with carnosinol were not due to changes in energy expenditure, physical activity, adiposity or body weight. Collectively, our findings illustrate a pathogenic role for RCS in obesity-related metabolic disorders, and provide validation for a promising new class of carbonyl-scavenging therapeutic compounds rationally derived from carnosine.
Ethan J. Anderson, Giulio Vistoli, Lalage A. Katunga, Katsuhiko Funai, Luca Regazzoni, T. Blake Monroe, Ettore Gilardoni, Luca Cannizzaro, Mara Colzani, Danilo De Maddis, Giuseppe Rossoni, Renato Canevotti, Stefania Gagliardi, Marina Carini, Giancarlo Aldini
Heart failure (HF) remains a major source of morbidity and mortality in the U.S. 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 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). Underlying observed differences in function was an unexpected differential regulation of STAT3-related genes in qv3J TAC hearts. In vitro experiments demonstrate that βIV-spectrin serves as a target for CaMKII phosphorylation, which regulates its stability. Cardiac-specific βIV-spectrin knockout (βIV-cKO) mice show STAT3 dysregulation, fibrosis and decreased cardiac function at baseline similar to WT TAC. STAT3 inhibition restored normal cardiac structure and function in βIV-cKO and WT TAC hearts. Our studies identify a novel 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 M. Nassal, Amara Greer-Short, Nehal J. Patel, Taylor Howard, Xianyao Xu, Birce Onal, Tony Satroplus, Deborah Y. Hong, Cemantha M. Lane, Alyssa Dalic, Sara N. Koenig, Adam C. Lehnig, Lisa A. Baer, Hassan Musa, Kristin I. Stanford, Sakima A. Smith, Peter J. Mohler, Thomas J. Hund
Hyperphosphatemic familial tumoral calcinosis (HFTC)/hyperostosis-hyperphosphatemia syndrome (HHS) is an autosomal recessive disorder of ectopic calcification due to deficiency of or resistance to intact fibroblast growth factor 23 (iFGF23). Inactivating mutations in FGF23, N-acetylgalactosaminyltransferase 3 (GALNT3), or KLOTHO have been reported to cause HFTC/HHS. We present the first identified case of autoimmune hyperphosphatemic tumoral calcinosis in an 8-year-old boy. In addition to the classical clinical and biochemical features of hyperphosphatemic tumoral calcinosis, the patient exhibited markedly elevated intact and C-terminal FGF23 levels suggestive of FGF23 resistance. However, no mutations in FGF23, KLOTHO, or fibroblast growth factor receptor 1 (FGFR1) were identified. He subsequently developed type 1 diabetes mellitus, which raised the possibility of an autoimmune cause for hyperphosphatemic tumoral calcinosis. Luciferase immunoprecipitation systems revealed significantly elevated FGF23 autoantibodies without detectable FGFR1 or KLOTHO autoantibodies. Using an in vitro FGF23 functional assay, the FGF23 autoantibodies in the patient’s plasma blocked downstream signaling via the MAPK/ERK signaling pathway in a dose-dependent manner. Thus, this report describes the first case of autoimmune hyperphosphatemic tumoral calcinosis with pathogenic autoantibodies targeting FGF23. Identification of this pathophysiology extends the etiologic spectrum of hyperphosphatemic tumoral calcinosis and suggests that immunomodulatory therapy may be an effective treatment.
Mary Scott Roberts, Peter D. Burbelo, Daniela Egli-Spichtig, Farzana Perwad, Christopher J. Romero, Shoji Ichikawa, Emily G. Farrow, Michael J. Econs, Lori C. Guthrie, Michael T. Collins, Rachel I. Gafni
The subthalamic nucleus (STN) is an effective therapeutic target for deep brain stimulation (DBS) for Parkinson’s disease (PD) and histamine level is elevated in the basal ganglia in PD patients. However, the endogenous histaminergic modulation on STN neuronal activities and the neuronal mechanism underlying STN-DBS are unknown. Here we report that STN neuronal firing patterns are more crucial than firing rates for motor control. Histamine excited STN neurons, but paradoxically ameliorated parkinsonian motor deficits, which we attributed to regularizing firing patterns of STN neurons via HCN2 channel coupled to H2 receptor. Intriguingly, DBS increased histamine release in the STN and regularized STN neuronal firing patterns under parkinsonian conditions. HCN2 contributed to the DBS-induced regularization of neuronal firing patterns, suppression of excessive beta oscillations, and alleviation of motor deficits in PD. The results reveal an indispensable role for regularizing STN neuronal firing patterns in amelioration of parkinsonian motor dysfunction and a functional compensation for histamine in parkinsonian basal ganglia circuitry. The findings provide insights into mechanisms of STN-DBS as well as potential therapeutic targets and STN-DBS strategies for PD.
Qian-Xing Zhuang, Guang-Ying Li, Bin Li, Chang-Zheng Zhang, Xiao-Yang Zhang, Kang Xi, Hong-Zhao Li, Jian-Jun Wang, Jing-Ning Zhu
Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system (CNS), induced by the adoptive transfer of myelin-reactive CD4+ T cells into naïve syngeneic mice. It is widely used as a rodent model of multiple sclerosis (MS). EAE lesion development is initiated when transferred CD4+ T cells access the CNS and are reactivated by local antigen presenting cells (APC) bearing endogenous myelin peptide/ MHC Class II complexes. The identity of the CNS resident, lesion-initiating APC is widely debated. Here we demonstrate that classical dendritic cells (cDC) normally reside in the meninges, brain, and spinal cord in the steady state. These cells are unique among candidate CNS APC in their ability to stimulate naïve, as well as effector, myelin-specific T cells to proliferate and produce pro-inflammatory cytokines directly ex vivo. cDC expanded in the meninges and CNS parenchyma in association with disease progression. Selective depletion of cDC led to a decrease in the number of myelin-primed donor T cells in the CNS and reduced the incidence of clinical EAE by half. Based on our findings, we propose that cDC, and the factors that regulate them, be further investigated as potential therapeutic targets in MS.
David A. Giles, Patrick C. Duncker, Nicole M. Wilkinson, Jesse M. Washnock-Schmid, Benjamin M. Segal
ASXL1 is frequently mutated in myeloid malignancies and is known to co-occur with other gene mutations. However, the molecular mechanisms underlying the leukemogenesis associated with ASXL1 and cooperating mutations remain to be elucidated. Here we report that Asxl1 loss cooperated with haploinsufficiency of Nf1, a negative regulator of the RAS signaling pathway, to accelerate the development of myeloid leukemia in mice. Loss of Asxl1 and Nf1 in hematopoietic stem and progenitor cells resulted in a gain-of-function transcriptional activation of multiple pathways critical for leukemogenesis, such as MYC, NRAS, and BRD4. The hyperactive MYC and BRD4 transcription programs were correlated with elevated H3K4 tri-methylation at the promoter regions of genes involving these pathways. Furthermore, pharmacological inhibition of both MAPK pathway and BET bromodomain prevented leukemia initiation and inhibited disease progression in Asxl1Δ/Δ;Nf1Δ/Δ mice. Concomitant mutations of ASXL1 and RAS pathway genes were associated with aggressive progression of myeloid malignancies in patients. This study sheds light on the understanding of the cooperative effect between epigenetic alterations and signaling pathways in accelerating the progression of myeloid malignancies and provides a rational therapeutic strategy for the treatment of myeloid malignancies with ASXL1 and RAS pathway gene mutations.
Peng Zhang, Fuhong He, Jie Bai, Shohei Yamamoto, Shi Chen, Lin Zhang, Mengyao Sheng, Lei Zhang, Ying Guo, Na Man, Hui Yang, Suyun Wang, Tao Cheng, Stephen D. Nimer, Yuan Zhou, Mingjiang Xu, Qian-Fei Wang, Feng-Chun Yang
The ubiquitin-proteasome system (UPS) degrades a protein molecule via two main steps: ubiquitination and proteasomal degradation. Extraproteasomal ubiquitin receptors are thought to couple the two steps but this proposition has not been tested in vivo with vertebrate animals. More importantly, impaired UPS performance plays a major role in cardiac pathogenesis including myocardial ischemia-reperfusion injury (IRI) but the molecular basis of the UPS impairment remains poorly understood. Ubiquilin1 is a bona fide extra-proteasomal ubiquitin receptor. Here we report that cardiomyocyte-restricted knockout of Ubiquilin1 (Ubqln1-CKO) in mice accumulated a surrogate UPS substrate (GFPdgn) and increased myocardial ubiquitinated proteins without altering proteasome activities, and resulted in a late-onset cardiomyopathy and a significantly shortened lifespan. When subject to regional myocardial ischemia-reperfusion, young Ubqln1-CKO mice showed significantly exacerbated cardiac malfunction and enlarged infarct size and, conversely, mice with transgenic Ubqln1 overexpression displayed attenuated IRI. Furthermore, Ubqln1 overexpression facilitated proteasomal degradation of oxidized proteins and the degradation of a UPS surrogate substrate in cultured cardiomyocytes without increasing autophagic flux. These findings demonstrate that Ubiquilin1 is essential to cardiac ubiquitination-proteasome coupling and that an inadequacy in the coupling represents a major pathogenic factor to myocardial IRI, identifying strengthening the coupling as a potential strategy to reduce IRI.
Chengjun Hu, Yihao Tian, Hongxin Xu, Bo Pan, Erin M. Terpstra, Penglong Wu, Hongmin Wang, Faqian Li, Jinbao Liu, Xuejun Wang
Breast cancer (BrCa) is the malignant tumor that most seriously threatens female health; however, the molecular mechanism underlying its progression remains unclear. Here, we found that conditional deletion of HIC1 in the mouse mammary gland might contribute to premalignant transformation in the early stage of tumor formation. Moreover, the chemokine CXCL14 secreted by HIC1-deleted BrCa cells bound to its novel cognate receptor GPR85 on mammary fibroblasts in the microenvironment and was responsible for activating these fibroblasts via the ERK1/2, Akt, and neddylation pathways, whereas the activated fibroblasts promoted BrCa progression via the induction of the epithelial–mesenchymal transition (EMT) by the CCL17/CCR4 axis. Finally, we confirmed that the HIC1-CXCL14-CCL17 loop was associated with the malignant progression of BrCa. Therefore, the crosstalk between HIC1-deleted BrCa cells and mammary fibroblasts might play a critical role in BrCa development. Taken together, exploring the progression of BrCa from the perspective of microenvironment will be beneficial for identifying the potential prognostic marker of breast tumor and providing the more effective treatment strategy.
Yingying Wang, Xiaoling Weng, Luoyang Wang, Mingang Hao, Yue Li, Lidan Hou, Yu Liang, Tianqi Wu, Mengfei Yao, Guowen Lin, Yiwei Jiang, Guohui Fu, Zhaoyuan Hou, Xiangjun Meng, Jinsong Lu, Jianhua Wang
Neutrophil extracellular traps (NETs) are involved in the pathogenesis of many infectious diseases, yet their dynamics and impact on HIV/SIV infection were not yet assessed. We hypothesized that SIV infection and the related microbial translocation trigger NET activation and release (NETosis), and investigated the interactions between NETs and immune cell populations and platelets. We compared and contrasted the levels of NETs between SIV-uninfected, SIV-infected, and SIV-infected antiretroviral-treated nonhuman primates. We also cocultured neutrophils from these animals with either peripheral blood mononuclear cells or platelets. Increased NET production was observed throughout SIV infection. In chronically infected animals, NETs were found in the gut, lung, liver, and in the blood vessels of kidney and heart. ART decreased NETosis, albeit above preinfection levels. NETs captured CD4+ and CD8+ T-cells, B-cells, and monocytes, irrespective of their infection status, potentially contributing to the indiscriminate generalized immune cell loss characteristic to HIV/SIV infection, and limiting the CD4+ T-cell recovery under ART. By capturing and facilitating aggregation of platelets, and through expression of increased tissue factor levels, NETs may also enhance HIV/SIV-related coagulopathy and promote cardiovascular comorbidities.
Ranjit Sivanandham, Egidio Brocca-Cofano, Noah Krampe, Elizabeth Falwell, Sindhuja Murali Kilapandal Venkatraman, Ruy M. Ribeiro, Cristian Apetrei, Ivona Pandrea
Hearing loss is a significant public health concern, affecting over 250 million people worldwide. Both genetic and environmental etiologies are linked to hearing loss, but in many cases the underlying cellular pathophysiology is not well understood, highlighting the importance of further discovery. We found that inactivation of the gene, Tmtc4 (transmembrane and tetratricopeptide repeat 4), which was broadly expressed in the mouse cochlea, caused acquired hearing loss in mice. Our data showed Tmtc4 enriched in the endoplasmic reticulum, and that it functioned by regulating Ca2+ dynamics and the unfolded protein response (UPR). Given this genetic linkage of the UPR to hearing loss, we demonstrated a direct link between the more common noise-induced hearing loss (NIHL) and the UPR. These experiments suggested a novel approach to treatment. We demonstrated that the small-molecule UPR and stress response modulator ISRIB (Integrated Stress Response Inhibitor), which activates eIF2B, prevented NIHL in a mouse model. Moreover, in an inverse genetic complementation approach, we demonstrated that mice with homozygous inactivation of both Tmtc4 and Chop had less hearing loss than knockout of Tmtc4 alone. This study implicated a novel mechanism for hearing impairment, highlighting a potential treatment approach for a broad range of human hearing-loss disorders.
Jiang Li, Omar Akil, Stephanie L. Rouse, Conor W. McLaughlin, Ian R. Matthews, Lawrence R. Lustig, Dylan K. Chan, Elliott H. Sherr