Abstract 29: MiR-33 Coordinately Regulates Macrophage Autophagy

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Mireille Ouimet ◽  
Hasini Ediriweera ◽  
Bhama Ramkhelawon ◽  
Elizabeth Hennessy ◽  
Denuja Karunakaran ◽  
...  
Keyword(s):  
Western Blot ◽  
Quantitative Pcr ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Cholesterol Efflux ◽  
Energy Homeostasis ◽  
Cholesterol Metabolism ◽  
Autophagic Flux ◽  
Microrna Target

Macrophage autophagy is thought to be essential for protecting from atherosclerosis, and compromised autophagy in macrophages of the artery wall leads to a number of pathologic processes including activation of the inflammasome, defective efferocytosis, and impaired cholesterol metabolism. Autophagy of lipid droplets (LDs) or “lipophagy” catabolizes stored lipids to maintain cellular energy homeostasis and plays a key role in cholesterol efflux by regulating LD-cholesterol mobilization, a rate-limiting step in macrophage reverse cholesterol transport (RCT). MicroRNA-33 (miR-33) is a well-established post-transcriptional RCT regulator, yet the complete mechanisms by which anti-miR33 exerts its beneficial effects on cholesterol metabolism are not known. Notably, microRNA target prediction algorithms identify a number of essential autophagy-related proteins (ATG5, ATG7) and lysosomal effectors (lysosomal-associated membrane protein 1 [LAMP1], lysosomal acid lipase [LAL]) as putative miR-33 targets. Quantitative PCR array profiling in mouse peritoneal macrophages revealed that a high proportion of autophagy genes are reciprocally regulated by miR-33 overexpression and inhibition. We validated a subset of genes in the autophagy pathway as bona fide miR-33 targets using 3′UTR luciferase assays and confirmed regulation of these targets by miR-33 using quantitative PCR and western blot analysis. Furthermore, we show that miR-33 indirectly regulates the expression of two master regulators of autophagy and lysosomal biogenesis gene programs: forkhead box O (FOXO) 3 and transcription factor EB (TFEB), via targeting of 5' AMP-activated protein kinase (AMPK). Inhibition of miR-33 in peritoneal macrophage in vitro enhanced cellular autophagic flux, as observed by fluorescence microscopy and western blot analysis, and autophagy was required for anti-miR33 promotion of cholesterol efflux. Furthermore, anti-miR33 treatment of atherosclerotic Ldlr-/- mice enhanced autophagy in plaque macrophages and triggered atherosclerosis regression. These data describe a novel role for miR-33 in the regulation of autophagy and identify additional mechanisms by which anti-miR33 therapy protects against atherosclerosis.

Radiosensitivity of glioma to Gamma Knife treatment enhanced in vitro and in vivo by RNA interfering Ku70 that is mediated by a recombinant adenovirus

2010 ◽  
Vol 113 (Special_Supplement) ◽  
pp. 228-235 ◽  
Author(s):  
Qiang Jia ◽  
Yanhe Li ◽  
Desheng Xu ◽  
Zhenjiang Li ◽  
Zhiyuan Zhang ◽  
...  
Keyword(s):  
Western Blot ◽  
Gamma Knife ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Glioma Cells ◽  
C6 Glioma ◽  
C6 Glioma Cells ◽  
C6 Cells

Object The authors sought to evaluate modification of the radiation response of C6 glioma cells in vitro and in vivo by inhibiting the expression of Ku70. To do so they investigated the effect of gene transfer involving a recombinant replication-defective adenovirus containing Ku70 short hairpin RNA (Ad-Ku70shRNA) combined with Gamma Knife treatment (GKT). Methods First, Ad-Ku70shRNA was transfected into C6 glioma cells and the expression of Ku70 was measured using Western blot analysis. In vitro, phenotypical changes in C6 cells, including proliferation, cell cycle modification, invasion ability, and apoptosis were evaluated using the MTT (3′(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide) assay, Western blot analysis, and cell flow cytometry. In vivo, parental C6 cells transfected with Ad-Ku70shRNA were implanted stereotactically into the right caudate nucleus in Sprague-Dawley rats. After GKS, apoptosis was analyzed using the TUNEL (terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling) method. The inhibitory effects on growth and invasion that were induced by expression of proliferating cell nuclear antigen and matrix metalloproteinase–9 were determined using immunohistochemical analyses. Results The expression of Ku70 was clearly inhibited in C6 cells after transfection with Ad-Ku70shRNA. In vitro following transfection, the C6 cells showed improved responses to GKT, including suppression of proliferation and invasion as well as an increased apoptosis index. In vivo following transfection of Ad-Ku70shRNA, the therapeutic efficacy of GKT in rats with C6 gliomas was greatly enhanced and survival times in these animals were prolonged. Conclusions Our data support the potential for downregulation of Ku70 expression in enhancing the radiosensitivity of gliomas. The findings of our study indicate that targeted gene therapy–mediated inactivation of Ku70 may represent a promising strategy in improving the radioresponsiveness of gliomas to GKT.

scholarly journals 9-PAHSA Improves Cardiovascular Complications by Promoting Autophagic Flux and Reducing Myocardial Hypertrophy in Db/Db Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Yan-Mei Wang ◽  
Shou-Ling Mi ◽  
Hong Jin ◽  
Qi-Lin Guo ◽  
Zhong-Yu Yu ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Blood Glucose ◽  
Western Blot ◽  
Vascular Calcification ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Myocardial Hypertrophy ◽  
Autophagic Flux ◽  
Glucose Levels ◽  
Blood Glucose Levels

Atherosclerotic cardiovascular disease is a common and severe complication of diabetes. There is a large need to identify the effective and safety strategies on diabetic cardiovascular disease (DCVD). 9-PAHSA is a novel endogenous fatty acid, and has been reported to reduce blood glucose levels and attenuate inflammation. We aim to evaluate the effects of 9-PAHSA on DCVD and investigate the possible mechanisms underlying it. Firstly, serum 9-PAHSA levels in human were detected by HPLC-MS/MS analysis. Then 9-PAHSA was synthesized and purified. The synthesized 9-PAHSA was gavaged to db/db mice with 50 mg/kg for 4 weeks. The carotid arterial plaque and cardiac structure was assessed by ultrasound. Cardiac autophagy was tested by western blot analysis, electron microscope and iTRAQ. The results showed that 9-PAHSA, in patients with type 2 diabetes mellitus (T2DM), was significantly lower than that in non-diabetic subjects. Administration of 9-PAHSA for 2 weeks reduced blood glucose levels. Ultrasound observed that continue administration of 9-PAHSA for 4 weeks ameliorated carotid vascular calcification, and attenuated myocardial hypertrophy and dysfunction in db/db mice. Electron microscopy showed continue 9-PAHSA treatment significantly increased autolysosomes, while dramatically decreased greases in the myocardial cells of the db/db mice. Moreover, iTRAQ analysis exhibited that continue 9-PAHSA treatment upregulated BAG3 and HSPB8. Furthermore, western blot analysis confirmed that 9-PAHSA down-regulated Akt/mTOR and activated PI3KIII/BECN1 complex in diabetic myocardium. Thus, 9-PAHSA benefits DCVD in diabetic mice by ameliorating carotid vascular calcification, promoting autophagic flux and reducing myocardial hypertrophy.

Regulation of Rhcg, an ammonia transporter, by aldosterone in the kidney

2021 ◽  
Author(s):  
Koji Eguchi ◽  
Yuichiro Izumi ◽  
Yukiko Yasuoka ◽  
Terumasa Nakagawa ◽  
Makoto Ono ◽  
...  
Keyword(s):  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Membrane Fraction ◽  
Potassium Level ◽  
Collecting Duct ◽  
Subcutaneous Administration ◽  
Extracellular Potassium ◽  
Membrane Expression

Rh C glycoprotein (Rhcg), an ammonia transporter, is a key molecule in urinary acid excretion and is expressed mainly in the intercalated cells (ICs) of the renal collecting duct. In the present study we investigated the role of aldosterone in the regulation of Rhcg expression. In in vivo experiments using C57BL/6J mice, Western blot analysis showed that continuous subcutaneous administration of aldosterone increased the expression of Rhcg in membrane fraction of the kidney. Supplementation of potassium inhibited the effect of aldosterone on the Rhcg. Next, mice were subjected to adrenalectomy with or without administration of aldosterone, and then ad libitum 0.14M NH4Cl containing water was given. NH4Cl load increased the expression of Rhcg in membrane fraction. Adrenalectomy decreased NH4Cl-induced Rhcg expression, which was restored by administration of aldosterone. Immunohistochemical studies revealed that NH4Cl load induced the localization of Rhcg at the apical membrane of ICs in the outer medullary collecting duct. Adrenalectomy decreased NH4Cl-induced membrane localization of Rhcg, which was restored by administration of aldosterone. For in vitro experiments, IN-IC cells, an immortalized cell line stably expressing Flag-tagged Rhcg (Rhcg-Flag), were used. Western blot analysis showed that aldosterone increased the expression of Rhcg-Flag in membrane fraction, while the increase in extracellular potassium level inhibited the effect of aldosterone. Both spironolactone and Gӧ6983, a PKC inhibitor, inhibited the expression of Rhcg-Flag in the membrane fraction. These results suggest that aldosterone regulates the membrane expression of Rhcg through the mineralocorticoid receptor and PKC pathways, which is modulated by extracellular potassium level.

Interfering With Hyaluronic Acid Metabolism Suppresses Glioma Cell Proliferation by Regulating Autophagy

2020 ◽  
Author(s):  
Tao Yan ◽  
Xin Chen ◽  
Hua Zhan ◽  
Penglei Yao ◽  
Ning Wang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Hyaluronic Acid ◽  
Tumor Microenvironment ◽  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Glioma Cell ◽  
Glioma Cells

Abstract BackgroundThe tumor microenvironment plays an important role in tumor progression. Hyaluronic acid (HA), an important component of the extracellular matrix in the tumor microenvironment, abnormally accumulates in a variety of tumors. Whereas the role of abnormal HA metabolism in glioma remains unclear. MethodsThe expression level of hyaluronic acid (HA) was analyzed by ELISA assay and proteins such as HAS3, CD44, P62, LC3, CCND1 and CCNB1 were measured with Western blot analysis. The cell viability and proliferation were measured by MTT and KI67 immunofluorescence staining respectively. Autophagic vesicles and autophagosomes were quantified by transmission electron microscopy (TEM) and GFP-RFP-LC3 fluorescence analysis respectively. Cell cycle was analyzed by flowcytometry and Western blot analysis. Immunohistochemical (IHC) staining was used to detect expression levels of HA, Ki67, HAS3 and CD44 in human and mouse tumor tissues. Lentivirus constructed HAS3 and CD44 knockout stable glioma cells were transplanted to BALB/C nude mice for in vivo experiments. 4-Methylumbelliferone (4MU) was also used to treat glioma bearing mice for verifing its anti-tumor ability. The expression curve of HAS3, CD44 and the disease-free survival (DFS) curves for HAS3, CD44 in patients with LGG and GBM was performed based on TCGA database. ResultsAs shown in the present study, HA, hyaluronic acid synthase 3 (HAS3) and a receptor of HA named CD44 are expressed at high levels in human glioma tissues and negatively correlated with the prognosis of patients with glioma. Silencing HAS3 or blocking CD44 inhibited the proliferation of glioma cells in vitro and in vivo. The underlying mechanism was attributed to the inhibition of autophagy flux and further maintaining glioma cell cycle arrest in G1 phase. More importantly, 4-Methylumbelliferone (4-MU), a small competitive inhibitor of UDP with the ability to penetrate the blood-brain barrier (BBB), also inhibited the proliferation of glioma cells in vitro and in vivo. ConclusionApproaches that interfere with HA metabolism by altering the expression of HAS3 and CD44 and the administration of 4-MU potentially represent effective strategies for glioma treatment.

scholarly journals A39 NOVEL GAIN OF FUNCTION NON-RECEPTOR TYROSINE KINASE MUTATIONS ARE LINKED TO THE PATHOGENESIS OF VEOIBD

2020 ◽  
Vol 3 (Supplement_1) ◽  
pp. 46-48
Author(s):  
M Mehta ◽  
L Wang ◽  
C Guo ◽  
N Warner ◽  
Q Li ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Western Blot ◽  
Receptor Tyrosine Kinase ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Intestinal Inflammation ◽  
De Novo ◽  
Single Gene ◽  
Gain Of Function

Abstract Background Very early-onset inflammatory bowel disease (VEOIBD) is an emerging global disease, that results in inflammation of the digestive tract. Severe forms of VEOIBD can be caused by mutations in a single gene (monogenic variants) and, can result in death. A candidate gene which codes for a non-receptor tyrosine kinase (nRTK) has recently been implicated as a monogenic cause of IBD (unpublished). Whole exome sequencing was performed in two unrelated children who presented with symptoms of IBD identifying two distinct de novo gain of function mutations (S550Y and P342T). Both mutations are located in the highly conserved region of the nRTK, and were predicted to have similar downstream effects. Furthermore, four other patients with a variety of adult-onset immune disorders have recently been identified with rare variants in the same gene (M450I, R42P, A353T, V433M, S550F) but, their potential gain of function status remains to be determined. Studies show that this nRTK is an essential mediator in inflammation. It is expressed in both intestinal epithelial and immune cells however, its role in infantile IBD is unclear. This protein is first activated by phosphorylation and is linked to activating downstream transcription factors such as ERK and JNK. All these target proteins play a meaningful role in intestinal inflammation in patients with IBD. Aims Since we identified P342T and S550Y to be gain of function, we wanted to determine if the new variants exhibit a similar downstream impact on target protein expression levels when compared with S550Y and P342T. We also wanted to identify if all variants can be rescued with a known nRTK inhibitor. It is hypothesized that the new variants are gain of function and that all variants can be rescued with the inhibitor. Methods Using western blot analysis, the activation of ERK, JNK and nRTK was compared between wildtype (WT) and mutants. This in vitro method helped identify the degree of activation. For the second part of the study, HEK293T cells were treated with inhibitor to test for a rescue of phenotypes via western blot analysis. Results Results show an increased activation of nRTK, ERK and JNK in all variants with S550Y and S550F having the highest activation. Furthermore, pharmacological inhibition using small molecular kinase inhibitors resulted in decreased activation of nRTK, ERK and JNK suggesting a rescue of phenotypes. Conclusions Characterizing the downstream functional impact of these nRTK variants is an important first step to determine if gain of function nRTK mutations drive IBD. With a rising prevalence of IBD worldwide, these findings may lead to the development of pharmacological nRTK inhibitors as a novel personalized therapeutic approach for these patients and possibly for the broader IBD population. Funding Agencies CIHR

scholarly journals In Vitro and In Vivo Effects of Fermented Oyster-Derived Lactate on Exercise Endurance Indicators in Mice

2020 ◽  
Vol 17 (23) ◽  
pp. 8811
Author(s):  
Storm N. S. Reid ◽  
Joung-Hyun Park ◽  
Yunsook Kim ◽  
Yi Sub Kwak ◽  
Byeong Hwan Jeon
Keyword(s):  
Lactate Dehydrogenase ◽  
Protein Expression ◽  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Biochemical Analysis ◽  
Positive Control ◽  
Exercise Endurance

Exogenous lactate administration has more recently been investigated for its various prophylactic effects. Lactate derived from potential functional foods, such as fermented oyster extract (FO), may emerge as a practical and effective method of consuming exogenous lactate. The current study endeavored to ascertain whether the lactate derived from FO may act on muscle cell biology, and to what extent this may translate into physical fitness improvements. We examined the effects of FO in vitro and in vivo, on mouse C2C12 cells and exercise performance indicators in mice, respectively. In vitro, biochemical analysis was carried out to determine the effects of FO on lactate content and muscle cell energy metabolism, including adenosine triphosphate (ATP) activity. Western blot analysis was also utilized to measure the protein expression of total adenosine monophosphate-activated protein kinase (AMPK), p-AMPK (Thr172), lactate dehydrogenase (LDH), succinate dehydrogenase (SDHA) and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in response to FO administration. Three experimental groups were formed: a positive control (PC) treated with 1% horse serum, FO10 treated with 10 μg/mL and FO50 treated with 50 μg/mL. In vivo, the effects of FO supplementation on exercise endurance were measured using the Rota-rod test, and Western blot analysis measured myosin heavy-chain 2 (MYH2) to assess skeletal muscle growth, alongside p-AMPK, total-AMPK, PGC-1α, cytochrome C and UCP3 protein expression. Biochemical analysis was also performed on muscle tissue to measure the changes in concentration of liver lactate, lactate dehydrogenase (LDH), glycogen and citrate. Five groups (n = 10/per group) consisted of a control group (CON), exercise group (Ex), positive control treated with Ex and 500 mg/kg Taurine (Ex-Tau), Ex and 100 mg/kg FO supplementation (Ex-FO100) and Ex and 200 mg/kg FO supplementation (Ex-FO200) orally administered over the 4-week experimental period.FO50 significantly increased PGC-1α expression (p < 0.001), whereas both FO10 and FO50 increased the expression of p-AMPK (p < 0.001), in C2C12 muscle cells, showing increased signaling important for mitochondrial metabolism and biogenesis. Muscle lactate levels were also significantly increased following FO10 (p < 0.05) and FO50 (p < 0.001). In vivo, muscle protein expression of p-AMPK (p < 0.05) and PGC-1α were increased, corroborating our in vitro results. Cytochrome C also significantly increased following FO200 intake. These results suggest that the effects of FO supplementation may manifest in a dose-response manner. FO administration, in vitro, and supplementation, in vivo, both demonstrate a potential for improvements in mitochondrial metabolism and biogenesis, and even for potentiating the adaptive effects of endurance exercise. Mechanistically, lactate may be an important molecule in explaining the aforementioned positive effects of FO.

The N-Terminally Truncated p53 Isoform Δ40p53 Influences Prognosis in Mucinous Ovarian Cancer

2012 ◽  
Vol 22 (3) ◽  
pp. 372-379 ◽  
Author(s):  
Gerda Hofstetter ◽  
Astrid Berger ◽  
Regina Berger ◽  
Arijana Zorić ◽  
Elena I. Braicu ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Confidence Interval ◽  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Quantitative Polymerase Chain Reaction ◽  
Hazard Ratio ◽  
Histological Subtypes ◽  
Mutational Status

ObjectiveThe tumor suppressor p53 generates the N-terminally truncated isoforms Δ40p53 and Δ133p53 that possess the ability to modulate p53 function in vitro. The aim of the present study was to evaluate the clinical relevance of p53 isoforms in the main histological subtypes of ovarian cancer.MethodsΔ40p53, Δ133p53, and full-length p53 (FLp53) expression was determined in 45 mucinous, 30 endometrioid, and 91 serous ovarian cancer specimens as well as 42 normal ovarian tissues using reverse transcriptase–quantitative polymerase chain reaction. In a subgroup of mucinous ovarian cancer cases, Δ40p53 expression was examined using Western blot analysis. A functional yeast-based assay and subsequent sequencing were performed to analyze the p53 mutational status.ResultsIn endometrioid cancer specimens, Δ133p53 expression was significantly lower than in mucinous and serous cases (P = 0.016) or in normal tissues (P = 0.004). Mucinous cancer samples showed elevated Δ40p53 expression as compared with normal ovarian tissues (P = 0.003). In addition, high Δ40p53 expression constituted an independent prognostic marker for recurrence-free but not for overall survival in patients with mucinous ovarian cancer (hazard ratio, 0.267; 95% confidence interval, 0.094–0.756 [P = 0.013]; hazard ratio, 0.453, 95% confidence interval, 0.193–1.064 [P = 0.069]). Western blot analysis confirmed the presence of p53β and Δ40p53α in a subset of patients with mucinous ovarian cancer. Expression of p53 isoforms was not associated with p53 mutational status or clinicopathologic parameters.ConclusionsWe show that expression of p53 isoforms differs in histological subtypes, thus supporting the hypothesis that histological subtypes represent distinct disease entities. In addition, we provide first evidence for a favorable role of Δ40p53 in patients with mucinous ovarian cancer.

scholarly journals Expression and subcellular localization of BNIP3 in hypoxic hepatocytes and liver stress

2009 ◽  
Vol 296 (3) ◽  
pp. G499-G509 ◽  
Author(s):  
Mallikarjuna R. Metukuri ◽  
Donna Beer-Stolz ◽  
Rajaie A. Namas ◽  
Rajeev Dhupar ◽  
Andres Torres ◽  
...  
Keyword(s):  
Cell Death ◽  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Ischemia Reperfusion ◽  
Redox Stress ◽  
No Donor ◽  
Interacting Protein

We have previously demonstrated that the Bcl-2/adenovirus EIB 19-kDa interacting protein 3 (BNIP3), a cell death-related member of the Bcl-2 family, is upregulated in vitro and in vivo in both experimental and clinical settings of redox stress and that nitric oxide (NO) downregulates its expression. In this study we sought to examine the expression and localization of BNIP3 in murine hepatocytes and in a murine model of hemorrhagic shock (HS) and ischemia-reperfusion (I/R). Freshly isolated mouse hepatocytes were exposed to 1% hypoxia for 6 h followed by reoxygenation for 18 h, and protein was isolated for Western blot analysis. Hepatocytes grown on coverslips were fixed for localization studies. Similarly, livers from surgically cannulated C57Bl/6 mice and from mice cannulated and subjected to 1–4 h of HS were processed for protein isolation and Western blot analysis. In hepatocytes, BNIP3 was expressed constitutively but was upregulated under hypoxic conditions, and this upregulation was countered by treatment with a NO donor. Surprisingly, BNIP3 was localized in the nucleus of normoxic hepatocytes, in the cytoplasm following hypoxia, and again in the nucleus following reoxygenation. Upregulation of BNIP3 partially required p38 MAPK activation. BNIP3 contributed to hypoxic injury in hepatocytes, since this injury was diminished by knockdown of BNIP3 mRNA. Hepatic BNIP3 was also upregulated in two different models of liver stress in vivo, suggesting that a multitude of inflammatory stresses can lead to the modulation of BNIP3. In turn, the upregulation of BNIP3 appears to be one mechanism of hepatocyte cell death and liver damage in these settings.

ADAMTS13 Binds VWF Via its C-Terminal CUB2 Domain.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 126-126 ◽  
Author(s):  
Weirui Zhang ◽  
David Motto ◽  
David Ginsburg
Keyword(s):  
Fusion Protein ◽  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Expression Vector ◽  
Full Length ◽  
Mammalian Expression ◽  
Partial Denaturation

Abstract Thrombotic thrombocytopenic purpura (TTP) is a life threatening illness due to a deficiency of the VWF-cleaving protease, ADAMTS13. The ADAMTS13 protein is composed of a propeptide, followed by a typical zinc metalloprotease domain. The C-terminal 2/3 of the molecule contains disintegrin-like, cystine-rich, and spacer domains, as well as a total of eight TSP1 motifs and two CUB domains. The function of this C-terminal portion of the molecule and its composite motifs is unknown, though TSP1 and CUB domains of other proteins have been shown to mediate protein-protein interactions. To further explore the interaction between ADAMTS13 and VWF, we cloned full length human cDNAs for both ADAMTS13 and VWF into the mammalian expression vector pcDNA3.1. These constructs were transiently transfected into 293T cells and COS cells respectively, and conditioned media collected for analysis. Using an anti-myc antibody, myc-tagged VWF co-immunoprecipitated (co-IP) with ADAMTS13, as demonstrated by western blot analysis using antisera raised against a C-terminal peptide derived from the predicted ADAMTS13 sequence. This direct interaction required partial denaturation of VWF in 1M urea, with no co-IP observed in the absence of urea. To map the segment within ADAMTS13 responsible for VWF binding, we cloned a series of overlapping ADAMTS13 fragments into the bacterial expression vector, Pet44b. Fusion proteins were purified by binding of the included His-tag to Ni-NTA beads and incubated with recombinant myc-VWF in the presence of 1M urea. Association with VWF was analyzed by co-IP with anti-myc followed by western blot analysis using an antibody to the C-terminal HSV-tag present in each fusion protein. The CUB2 (Glu1298- Thr1427) fusion protein co-IP’d with full-length VWF and also demonstrated concentration-dependent competition with full-length ADAMTS13 for VWF binding. In summary, we have demonstrated a direct protein-protein interaction between VWF and ADAMTS13. Binding requires partial denaturation of VWF and appears to be mediated primarily through contacts with the ADAMTS13 CUB2 domain. This interaction may account for the previously observed co-purification of VWF and ADAMTS13 from human plasma. Furthermore, the requirement for 1M urea suggests that this interaction may only occur physiologically under conditions of high shear. Though others have shown that the C-terminal domains of ADAMTS13, including CUB2, are not required for VWF cleavage in vitro, our data, together with several C-terminal mutations previously reported in TTP patients, suggest that interactions between VWF and the ADAMTS13 CUB2 domain may be important in vivo.

Identification of a Novel Epigenetic Regulator That Acts As a Tumor Suppressor in the Development of MLL AML Leukemic Stem Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3923-3923
Author(s):  
Hangyu Yi ◽  
Halina Leung ◽  
Aliaksei Holik ◽  
Florida Voli ◽  
Marie-Liesse Asselin-Labat ◽  
...  
Keyword(s):  
Stem Cells ◽  
Tumor Suppressor ◽  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Histone Demethylase ◽  
Leukemic Stem Cells ◽  
Hematopoietic Stem ◽  
Promising Therapeutic Approach

Abstract Acute myeloid leukemia (AML) is still a deadly form of leukemia due to frequent relapse caused by the persistence of drug-resistant leukemic stem cells (LSCs). We have previously demonstrated a crucial role for β-catenin signaling in regulating LSCs and identified GPR84 as an important β-catenin regulator in the maintenance of mixed-lineage leukemia (MLL) LSCs (Wang et al., Science 2010; Dietrich et al., Blood 2014). Hence, targeting LSCs by pharmacological inhibition of GPR84/β-catenin signaling represents a promising therapeutic approach. In collaboration with a pharmaceutical company that has developed a novel GPR84 antagonist (GP), we investigated the effect of GP in MLL pre-leukemic stem cell (pre-LSC) function. GP (20 μM) significantly inhibited the colony forming ability of MLL pre-LSCs (P < 0.0001) but had little effect on normal hematopoietic stem cells. Quantitative RT-PCR and western blot analysis confirmed GP-induced downregulation of GPR84 target genes, including Hoxa5, Hoxa7 and Meis1a, indicating GP-induced inhibition of GPR84 signaling. To further examine the mechanism of GPR84 inhibition on MLL pre-LSCs, we evaluated several epigenetic regulators (i.e. JMJD1c and EZH2) known to promote leukemogenesis (Zhu et al., ‎J Clin Invest 2016; Tanaka et al., Blood 2012). Western blot analysis showed that inhibition of GPR84 signaling did not alter the expression of JMJD1c or EZH2. However, we observed a significant increase in the expression of a novel and not-yet-characterized histone demethylase (HD) in AML. To investigate the role of HD in AML leukemogenesis, we overexpressed HD in MLL pre-LSCs and subsequent serial replating assay showed a marked reduction in colony forming ability (P < 0.005), indicating impaired self-renewal in vitro. Consistent with our in vitro observations, in vivo transplantation in syngeneic mice revealed a significant delay in leukemia onset and increase in mouse survival (P < 0.001). We next performed western blot analysis to examine the demethylase activity of HD, and our data revealed that HD overexpression caused a substantial reduction in global histone 3 lysine 36 dimethylation (H3K36me2), an epigenetic mark normally associated with transcriptional activation and elongation. In order to identify genes regulated by HD through demethylation of H3K36me2, we performed H3K36me2 ChIP-seq on HD overexpressing MLL pre-LSCs. Our analysis identified several genes including anti-apoptotic protein Mcl-1 and angiogenic receptor Nrp1, which are known to be involved in AML leukemogenesis, with decreased H3K36me2 mark on both the transcriptional start site and gene body. Subsequent western blot analysis confirmed the decreased expression of both Mcl-1 and Nrp1 in HD overexpressing pre-LSCs. Given the prominent roles of anti-apoptosis and angiogenesis in the development of hematologic malignancies such as leukemia, we are currently evaluating these mechanisms caused by HD overexpression in an important subtype of AML. Taken together, our study identifies a novel histone demethylase that acts downstream of GPR84 signaling to function as a potent tumor suppressor in the development of MLL LSCs. Disclosures No relevant conflicts of interest to declare.

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