Neuronal hypothalamic regulation of body metabolism and bone density is galanin-dependent

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Abstract

In the brain, the ventral hypothalamus (VHT) regulates energy and bone metabolism. Whether this regulation uses the same or different neuronal circuits is unknown. Alteration of AP1 signaling in the VHT increases energy expenditure, glucose utilization, and bone density, yet the specific neurons responsible for each or all of these phenotypes are not identified. Using neuron-specific genetically targeted AP1 alterations as a tool in adult mice, we found that AgRP- or POMC- expressing neurons, predominantly present in the arcuate nucleus (ARC) within the VHT, stimulate whole body energy expenditure, glucose utilization and bone formation and density, although their effects on bone resorption differed. In contrast, AP1 alterations in Steroidogenic factor 1 (SF1)-expressing neurons, present in the ventromedial hypothalamus (VMH), increase energy, but decrease bone density, suggesting that these effects are independent. Altered AP1 signaling also increased the levels of the neuromediator galanin in the hypothalamus and global galanin deletion, VHT galanin silencing using shRNA, or pharmacological galanin receptor blockade, counteracted the observed effects on energy and bone. Thus, AP1 antagonism reveals that AgRP- and POMC- expressing neurons can stimulate body metabolism and increase bone density, with galanin acting as a central downstream effector. The results obtained with SF1-expressing neurons, however, indicate that bone homeostasis is not always dictated by the global energy status, and vice versa.

Authors

Anna Idelevich, Kazusa Sato, Kenichi Nagano, Glenn Rowe, Francesca Gori, Roland Baron

Contributions of inflammation and tumor microenvironment to neurofibroma tumorigenesis

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Abstract

Neurofibromatosis type 1 associates with multiple neoplasms and the Schwann cell tumor neurofibroma is the most prevalent. A hallmark feature of neurofibroma is mast cell infiltration which is recruited by chemoattractant stem cell factor (SCF) that has been suggested to sustain neurofibroma tumorigenesis. In this study, using new genetically engineered Scf mice, we decipher the contributions of tumor-derived SCF and mast cells to neurofibroma development. We demonstrate that mast cell infiltration is dependent on SCF from tumor Schwann cells. However, removal of mast cells by depleting this main SCF source only slightly affects neurofibroma progression. Other inflammation signatures show that all neurofibromas are associated with high levels of macrophages regardless of Scf status. These findings suggest an active inflammation in neurofibromas and partly explain why mast cell removal alone is not sufficient to relieve tumor burden in this experimental neurofibroma model. Furthermore, we show that plexiform neurofibromas are highly associated with injury-prone spinal nerves that are close to flexible vertebras. In summary, our study details the role of inflammation in neurofibromagenesis. These data paired with the observed tumor locations indicate that prevention of inflammation, and possibly nerve injury, are therapeutic approaches for neurofibroma prophylaxis and treatment that should be explored.

Authors

Chung-Ping Liao, Reid C. Booker, Jean-Philippe Brosseau, Zhiguo Chen, Juan Mo, Edem Tchegnon, Yong Wang, D. Wade Clapp, Lu Q. Le

PPARγ deacetylation dissociates thiazolidinedione’s metabolic benefits from its adverse effects

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Abstract

Thiazolidinediones (TZDs) are PPARγ agonists with potent insulin-sensitizing effects. However, their use has been curtailed by significant adverse effects on weight, bone, heart, and hemodynamic balance. TZDs induce the deacetylation of PPARγ on K268 and K293 to cause the browning of white adipocytes. Here we showed that targeted PPARγ mutations resulting in constitutive deacetylation (K268R/K293R, 2KR) increased energy expenditure, and protected from visceral adiposity and diet-induced obesity by augmenting brown remodeling of white adipose tissues. Strikingly, when 2KR mice were treated with rosiglitazone, they maintained the insulin-sensitizing, glucose-lowering response to TZDs, while displaying little, if any, adverse effects on fat deposition, bone density, fluid retention, and cardiac hypertrophy. Thus, deacetylation appears to fulfill the goal of dissociating the metabolic benefits of PPARγ activation from its adverse effects. Strategies to leverage PPARγ deacetylation may lead to the design of safer, more effective agonists of this nuclear receptor in the treatment of metabolic diseases.

Authors

Michael J. Kraakman, Qiongming Liu, Jorge Postigo-Fernandez, Ruiping Ji, Ning Kon, Delfina Larrea, Maria Namwanje, Lihong Fan, Michelle Chan, Estela Area-Gomez, Wenxian Fu, Remi J. Creusot, Li Qiang

Hypercholesterolemia induces T cell expansion in humanized immune mice

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Abstract

Emerging data suggest that hypercholesterolemia has stimulatory effects on adaptive immunity and that these effects can promote atherosclerosis and perhaps other inflammatory diseases. However, research in this area has relied primarily on inbred strains of mice, whose adaptive immune system can differ substantially from that of humans. Moreover, the genetically induced hypercholesterolemia in these models typically results in plasma cholesterol levels that are much higher than those in most humans. To overcome these obstacles, we studied human immune system-reconstituted mice (hu-mice) rendered hypercholesterolemic by treatment with AAV8- PCSK9 and a high-fat/high-cholesterol Western-type diet (WD). These mice had a high percentage of human T cells and moderate hypercholesterolemia. Compared with hu-mice having lower plasma cholesterol, the PCSK9-WD mice developed a T cell-mediated inflammatory response in the lung and liver. Human CD4+ and CD8+ T cells bearing an effector memory phenotype were significantly elevated in the blood, spleen, and lungs of PCSK9-WD hu-mice, while splenic and circulating regulatory T cells were reduced. These data show that moderately high plasma cholesterol can disrupt human T cell homeostasis in vivo. This process may not only exacerbate atherosclerosis but also contribute to T cell-mediated inflammatory diseases in the setting of hypercholesterolemia.

Authors

Jonathan D. Proto, Amanda C. Doran, Manikandan Subramanian, Hui Wang, Mingyou Zhang, Erdi Sozen, Christina Rymond, George Kuriakose, Vivette D'Agati, Robert Winchester, Megan Sykes, Yong-Guang Yang, Ira Tabas

Blocking IFNRA1 inhibits multiple myeloma-driven Treg expansion and immunosuppression

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Abstract

Despite significant advances in the treatment of multiple myeloma (MM), most patients succumb to disease progression. One of the major immunosuppressive mechanisms that is believed to play a role in myeloma progression, is the expansion of regulatory T-cells (Tregs). In this study, we demonstrate that myeloma cells drive Treg expansion and activation by secreting type-1 interferon (IFN). Blocking IFNAR1 (interferon alpha and beta receptor 1) on Tregs significantly decreases both, myeloma-associated Treg immunosuppressive function and myeloma progression. Using syngeneic transplantable murine myeloma models and bone marrow (BM) aspirates of multiple myeloma patients, we found that Tregs were expanded and activated in the BM microenvironment at early stages of myeloma development. Selective depletion of Tregs led to a complete remission and prolonged survival in mice injected with myeloma cells. Further analysis of the interaction between myeloma cells and Tregs using gene sequencing and enrichment analysis uncovered a feedback loop, wherein myeloma-cell-secreted type-1 IFN induced proliferation and expansion of Tregs. By using IFNAR1-blocking antibody treatment and IFNAR1 knockout Tregs, we demonstrated a significant decrease in myeloma-associated Treg proliferation, which was associated with longer survival of myeloma-injected mice. Our results thus suggest that blocking type-1 IFN signaling represents a potential strategy to target immunosuppressive Treg function in MM.

Authors

Yawara Kawano, Oksana Zavidij, Jihye Park, Michele Moschetta, Katsutoshi Kokubun, Tarek H. Mouhieddine, Salomon Manier, Yuji Mishima, Naoka Murakami, Mark Bustoros, Romanos Sklavenitis Pistofidis, Mairead Reidy, Yu J. Shen, Mahshid Rahmat, Pavlo Lukyanchykov, Esilida Sula Karreci, Shokichi Tsukamoto, Jiantao Shi, Satoshi Takagi, Daisy Huynh, Antonio Sacco, Yu-Tzu Tai, Marta Chesi, P. Leif Bergsagel, Aldo M. Roccaro, Jamil Azzi, Irene M. Ghobrial

UHRF1 epigenetically orchestrates smooth muscle cell plasticity in arterial disease

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Abstract

Adult vascular smooth muscle cells (VSMCs) possess the peculiar ability to de-differentiate in response to extracellular cues, such as vascular damage and inflammation. De-differentiated VSMCs are proliferative, migratory, and have decreased contractile capacity. VSMC dedifferentiation contributes not only to vascular repair, but also to cardiovascular pathologies, such as intimal hyperplasia/restenosis in coronary artery or peripheral vascular diseases and arterial aneurysm. We here demonstrate the role of ubiquitin-like, containing PHD and RING finger domains, 1 (UHRF1) as an epigenetic master regulator of VSMC plasticity. The expression of UHRF1 correlates with the development of a wide array of vascular pathologies associated also with modulation of non-coding RNAs, such as microRNAs. Importantly, miR-145, a pivotal gene regulating VSMC plasticity, which is reduced in vascular diseases, was found to control Uhrf1 mRNA translation. In turn, UHRF1 triggers VSMC proliferation by directly repressing the promoters of cell cycle inhibitor genes, such as p21 and p27, and of key pro-differentiation genes via the methylation of DNA and histones. Local vascular viral delivery of Uhrf1 shRNAs or Uhrf1 VSMC-specific deletion prevented intimal hyperplasia in mouse carotid artery and decreased vessel damage in a mouse model of aortic aneurysm.Our study demonstrates the fundamental role of Uhrf1 in regulating VSMC phenotype by promoting proliferation and de-differentiation. UHRF1 targeting may hold therapeutic potential in vascular pathologies, modulating also the VSMC component.

Authors

Leonardo Elia, Paolo Kunderfranco, Pierluigi Carullo, Marco Vacchiano, Floriana Maria Farina, Ignacio Fernando Hall, Stefano Mantero, Cristina Panico, Roberto Papait, Gianluigi Condorelli, Manuela Quintavalle

HMGB1 links chronic liver injury to progenitor responses and hepatocarcinogenesis

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Abstract

Cell death is a key driver of disease progression and carcinogenesis in chronic liver disease (CLD), highlighted by the well-established clinical correlation between hepatocellular death and risk for the development of cirrhosis and hepatocellular carcinoma (HCC). Moreover, hepatocellular death is sufficient to trigger fibrosis and HCC in mice. However, the pathways through which cell death drives CLD progression remain elusive. Here, we tested the hypothesis that high-mobility group box 1 (HMGB1), a damage-associated molecular pattern (DAMP) with key roles in acute liver injury, may link cell death to injury responses and hepatocarcinogenesis in CLD. While liver-specific HMGB1 deficiency did not significantly affect chronic injury responses such as fibrosis, regeneration and inflammation, it inhibited ductular/progenitor cell expansion and hepatocyte metaplasia. HMGB1 promoted ductular expansion independently of active secretion in a non-autonomous fashion, consistent with its role as DAMP. Liver-specific HMGB1 deficiency reduced HCC development in three models with chronic injury but not in a model lacking chronic liver injury. Similar to CLD, HMGB1 ablation reduced the expression of progenitor and oncofetal markers, a key determinant of HCC aggressiveness, in tumors. In summary, HMGB1 links hepatocyte death to ductular reaction, progenitor signature and hepatocarcinogenesis in CLD.

Authors

Céline Hernandez, Peter Huebener, Jean-Philippe Pradere, Daniel J. Antoine, Richard A. Friedman, Robert F. Schwabe

HMGB1 promotes ductular reaction and tumorigenesis in autophagy-deficient livers

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Abstract

Autophagy is important for liver homeostasis and the deficiency leads to injury, inflammation, ductular reaction (DR), fibrosis, and tumorigenesis. It is not clear how these events are mechanistically linked to autophagy deficiency. Here we reveal the role of highmobility group box 1 (HMGB1) in two of these processes. First, HMGB1 was required for DR, which represents the expansion of hepatic progenitor cells (HPC) implicated in liver repair and regeneration. DR caused by hepatic toxic diets (DDC or CDE) also depended on HMGB1, indicating that HMGB1 may be generally required for DR in various injury scenarios. Second, HMGB1 promoted tumor development in autophagy deficient livers. Receptor for advanced glycation end product (RAGE), a receptor for HMGB1, was required in the same two processes, and could mediate HMGB1’s proliferative effects in isolated HPC. HMGB1 was released from autophagy-deficient hepatocytes independently of cellular injury, but depending on NRF2 and inflammasome, which was activated by NRF2. Pharmacological or genetic activation of NRF2 alone without disabling autophagy or causing injury was sufficient to cause inflammasomedependent HMGB1 release. In conclusion, HMGB1 release is a critical mechanism in hepatic pathogenesis under the autophagy deficient condition, which leads to HPC expansion but also tumor development.

Authors

Bilon Khambu, Nazmul Huda, Xiaoyun Chen, Daniel J. Antoine, Yong Li, Guoli Dai, Ulrike A. Köhler, Wei-Xing Zong, Satoshi Waguri, Sabine Werner, Tim D. Oury, Zheng Dong, Xiao-Ming Yin

Coexisting genomic aberrations associated with lymph node metastasis in breast cancer

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Abstract

Single cancer cell sequencing studies currently use randomly-selected cells, limiting correlations between genomic aberrations, morphology and spatial localization. We laser-captured microdissected single cells from morphologically-distinct areas of primary breast cancer and corresponding lymph node metastasis and performed whole-exome or deep-target sequencing of greater than 100 such cells. Two major subclones co-existed in different areas of the primary tumor, and the lymph node metastasis originated from a minor subclone in the invasive front of the primary tumor with additional copy number changes including 8q gain, but no additional point mutations in driver genes. Lack of metastasis-specific driver events lead us to assess whether other clonal and subclonal genomic aberrations pre-existing in primary tumors contribute to lymph node metastasis. Gene mutations and copy number variations analyzed in five breast cancer tissue sample sets revealed that copy number variations in several genomic regions, including areas within chromosome 1p, 8q, 9p, 12q and 20q, harboring several metastasis-associated genes, were consistently associated with lymph node metastasis. Moreover, clonal expansion was observed in an area of morphologically-normal breast epithelia, likely driven by a driver mutation and a subsequent amplification in chromosome 1q. Our study illuminates the molecular evolution of breast cancer and genomic aberrations contributing to metastases.

Authors

Li Bao, Zhaoyang Qian, Maria B. Lyng, Ling Wang, Yuan Yu, Ting Wang, Xiuqing Zhang, Huanming Yang, Nils Brünner, Jun Wang, Henrik J. Ditzel

Mutant ataxin1 disrupts cerebellar development in spinocerebellar ataxia type 1

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Abstract

Spinocerebellar ataxia type 1 (SCA1) is an adult-onset neurodegenerative disease caused by a polyglutamine expansion in the protein ATXN1, which is involved in transcriptional regulation. Although symptoms appear relatively late in life, primarily from cerebellar dysfunction, pathogenesis begins early, with brain-wide transcriptional changes detectable as early as a week after birth in SCA1 knock-in mice. Given the importance of this postnatal period for cerebellar development, we asked whether this region might be developmentally altered by mutant ATXN1. We found that expanded ATXN1 stimulates the proliferation of postnatal cerebellar stem cells in SCA1 mice. These hyper-proliferating stem cells tended to differentiate into GABAergic inhibitory interneurons rather than astrocytes; this significantly increased the GABAergic inhibitory interneuron synaptic connections, disrupting cerebellar Purkinje cell function in a non-cell autonomous manner. We confirmed the increased basket cell-Purkinje cell connectivity in human SCA1 patients. Mutant ATXN1 thus alters the neural circuitry of the developing cerebellum, setting the stage for the later vulnerability of Purkinje cells to SCA1. We propose that other late-onset degenerative diseases may also be rooted in subtle developmental derailments.

Authors

Chandrakanth Reddy Edamakanti, Jeehaeh Do, Alessandro Didonna, Marco Martina, Puneet Opal