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Wang X, Zhang S, Zhang Z, Mazloum NA, Lee EYC, Lee MYW. The DHX9 helicase interacts with human DNA polymerase δ4 and stimulates its activity in D-loop extension synthesis. DNA Repair (Amst) 2023; 128:103513. [PMID: 37285751 DOI: 10.1016/j.dnarep.2023.103513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/28/2023] [Accepted: 05/11/2023] [Indexed: 06/09/2023]
Abstract
The extension of the invading strand within a displacement loop (D-loop) is a key step in homology directed repair (HDR) of doubled stranded DNA breaks. The primary goal of these studies was to test the hypotheses that 1) D-loop extension by human DNA polymerase δ4 (Pol δ4) is facilitated by DHX9, a 3' to 5' motor helicase, which acts to unwind the leading edge of the D-loop, and 2) the recruitment of DHX9 is mediated by direct protein-protein interactions between DHX9 and Pol δ4 and/or PCNA. DNA synthesis by Pol δ4 was analyzed in a reconstitution assay by the extension of a 93mer oligonucleotide inserted into a plasmid to form a D-loop. Product formation by Pol δ4 was monitored by incorporation of [α-32P]dNTPs into the 93mer primer followed by denaturing gel electrophoresis. The results showed that DHX9 strongly stimulated Pol δ4 mediated D-loop extension. Direct interactions of DHX9 with PCNA, the p125 and the p12 subunits of Pol δ4 were demonstrated by pull-down assays with purified proteins. These data support the hypothesis that DHX9 helicase is recruited by Pol δ4/PCNA to facilitate D-loop synthesis in HDR, and is a participant in cellular HDR. The involvement of DHX9 in HDR represents an important addition to its multiple cellular roles. Such helicase-polymerase interactions may represent an important aspect of the mechanisms involved in D-loop primer extension synthesis in HDR.
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Affiliation(s)
- Xiaoxiao Wang
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA
| | - Sufang Zhang
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA
| | - Zhongtao Zhang
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA
| | - Nayef A Mazloum
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA
| | - Ernest Y C Lee
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA
| | - Marietta Y W Lee
- Department of Biochemistry and Molecular Biology, New York Medical College, 15 Dana Road, Valhalla, NY 10595, USA.
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Majeed Y, Madani AY, Altamimi AI, Courjaret R, Vakayil M, Fountain SJ, Machaca K, Mazloum NA. STAT1- and NFAT-independent amplification of purinoceptor function integrates cellular senescence with interleukin-6 production in preadipocytes. Br J Pharmacol 2023; 180:609-627. [PMID: 36321760 DOI: 10.1111/bph.15978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 09/03/2022] [Accepted: 10/11/2022] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND AND PURPOSE Senescent preadipocytes promote adipose tissue dysfunction by secreting pro-inflammatory factors, although little is known about the mechanisms regulating their production. We investigated if up-regulated purinoceptor function sensitizes senescent preadipocytes to cognate agonists and how such sensitization regulates inflammation. EXPERIMENTAL APPROACH Etoposide was used to trigger senescence in 3T3-L1 preadipocytes. CRISPR/Cas9 technology or pharmacology allowed studies of transcription factor function. Fura-2 imaging was used for calcium measurements. Interleukin-6 levels were quantified using quantitative PCR and ELISA. Specific agonists and antagonists supported studies of purinoceptor coupling to interleukin-6 production. Experiments in MS1 VEGF angiosarcoma cells and adipose tissue samples from obese mice complemented preadipocyte experiments. KEY RESULTS DNA damage-induced senescence up-regulated purinoceptor expression levels in preadipocytes and MS1 VEGF angiosarcoma cells. ATP-evoked Ca2+ release was potentiated in senescent preadipocytes. ATP enhanced interleukin-6 production, an effect mimicked by ADP but not UTP, in a calcium-independent manner. Senescence-associated up-regulation and activation of the adenosine A3 receptor also enhanced interleukin-6 production. However, nucleotide hydrolysis was not essential because exposure to ATPγS also enhanced interleukin-6 secretion. Pharmacological experiments suggested coupling of P2X ion channels and P2Y12 -P2Y13 receptors to downstream interleukin-6 production. Interleukin-6 signalling exacerbated inflammation during senescence and compromised adipogenesis. CONCLUSIONS AND IMPLICATIONS We report a previously uncharacterized link between cellular senescence and purinergic signalling in preadipocytes and endothelial cancer cells, raising the possibility that up-regulated purinoceptors play key modulatory roles in senescence-associated conditions like obesity and cancer. There is potential for exploitation of specific purinoceptor antagonists as therapeutics in inflammatory disorders.
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Affiliation(s)
- Yasser Majeed
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
| | - Aisha Y Madani
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
| | - Ahmed I Altamimi
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
| | - Raphael Courjaret
- Department of Physiology and Biophysics, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
| | - Muneera Vakayil
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
- College of Health and Life Sciences, Hamad Bin Khalifa University, Qatar Foundation, Doha, Qatar
| | - Samuel J Fountain
- School of Biological Sciences, University of East Anglia, Norwich, UK
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
| | - Nayef A Mazloum
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
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Madani AY, Majeed Y, Abdesselem HB, Agha MV, Vakayil M, Sukhun NKA, Halabi NM, Kumar P, Hayat S, Elrayess MA, Rafii A, Suhre K, Mazloum NA. Signal Transducer and Activator of Transcription 3 (STAT3) Suppresses STAT1/Interferon Signaling Pathway and Inflammation in Senescent Preadipocytes. Antioxidants (Basel) 2021; 10:antiox10020334. [PMID: 33672392 PMCID: PMC7927067 DOI: 10.3390/antiox10020334] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 12/20/2022] Open
Abstract
Obesity promotes premature aging and dysfunction of white adipose tissue (WAT) through the accumulation of cellular senescence. The senescent cells burden in WAT has been linked to inflammation, insulin-resistance (IR), and type 2 diabetes (T2D). There is limited knowledge about molecular mechanisms that sustain inflammation in obese states. Here, we describe a robust and physiologically relevant in vitro system to trigger senescence in mouse 3T3-L1 preadipocytes. By employing transcriptomics analyses, we discovered up-regulation of key pro-inflammatory molecules and activation of interferon/signal transducer and activator of transcription (STAT)1/3 signaling in senescent preadipocytes, and expression of downstream targets was induced in epididymal WAT of obese mice, and obese human adipose tissue. To test the relevance of STAT1/3 signaling to preadipocyte senescence, we used Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated protein 9 (CRISPR/Cas9) technology to delete STAT1/3 and discovered that STAT1 promoted growth arrest and cooperated with cyclic Guanosine Monophosphate-Adenosine Monophosphate (GMP-AMP) synthase-stimulator of interferon genes (cGAS-STING) to drive the expression of interferon β (IFNβ), C-X-C motif chemokine ligand 10 (CXCL10), and interferon signaling-related genes. In contrast, we discovered that STAT3 was a negative regulator of STAT1/cGAS-STING signaling-it suppressed senescence and inflammation. These data provide insights into how STAT1/STAT3 signaling coordinates senescence and inflammation through functional interactions with the cGAS/STING pathway.
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Affiliation(s)
- Aisha Y. Madani
- College of Health & Life Sciences, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha 34110, Qatar; (A.Y.M.); (M.V.)
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (Y.M.); (N.K.A.S.)
| | - Yasser Majeed
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (Y.M.); (N.K.A.S.)
| | - Houari B. Abdesselem
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha 34110, Qatar;
| | - Maha V. Agha
- Translational Research Institute, Academic Health System, Hamad Medical Corporation, Doha 3050, Qatar;
| | - Muneera Vakayil
- College of Health & Life Sciences, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha 34110, Qatar; (A.Y.M.); (M.V.)
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (Y.M.); (N.K.A.S.)
| | - Nour K. Al Sukhun
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (Y.M.); (N.K.A.S.)
| | - Najeeb M. Halabi
- Department of Genetic Medicine, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (N.M.H.); (A.R.)
| | | | - Shahina Hayat
- Department of Physiology and Biophysics, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (S.H.); (K.S.)
| | | | - Arash Rafii
- Department of Genetic Medicine, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (N.M.H.); (A.R.)
| | - Karsten Suhre
- Department of Physiology and Biophysics, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (S.H.); (K.S.)
| | - Nayef A. Mazloum
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar (WCM-Q), Qatar Foundation, Doha 24144, Qatar; (Y.M.); (N.K.A.S.)
- Correspondence:
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Diboun I, Ramanjaneya M, Ahmed L, Bashir M, Butler AE, Albagha O, Abou-Samra AB, Atkin SL, Mazloum NA, Elrayess MA. Metabolomic Profiling of Pregnancies With Polycystic Ovary Syndrome Identifies a Unique Metabolic Signature and Potential Predictive Biomarkers of Low Birth Weight. Front Endocrinol (Lausanne) 2021; 12:638727. [PMID: 34211435 PMCID: PMC8239387 DOI: 10.3389/fendo.2021.638727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 05/10/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Polycystic ovary syndrome (PCOS) is a complex syndrome with clinical features of an endocrine/metabolic disorder. Various metabolites show significant association with PCOS; however, studies comparing the metabolic profile of pregnant women with and without PCOS are lacking. In this study, metabolomics analysis of blood samples collected from PCOS women and age and BMI matched controls in the second trimester of pregnancy was performed to identify metabolic differences between the two groups and determine their association with pregnancy outcome. METHODS Sixteen PCOS and fifty-two healthy women in their second trimester underwent targeted metabolomics of plasma samples using tandem mass spectrometry with the Biocrates MxP® Quant 500 Kit. Linear regression models were used to identify the metabolic alterations associated with PCOS, followed by enrichment and Receiver Operating Characteristic (ROC) analyses to determine the best indicators of pregnancy outcomes. RESULTS PCOS women had lower birth weight babies compared to healthy controls. As a group, systolic blood pressure (SBP) at both second trimester and at delivery negatively correlated with birth weight. Regression models indicated significant increases in the triglycerides C20:4_C34:3 and C18:2_C38:6 in the PCOS group [false discovery rate (FDR) <0.05]. Enrichment analysis revealed significant elevations in triglycerides containing arachidonic acid, linoleic acid and palmitic acid in the PCOS group. A number of indicators of baby birth weight were identified including SBP at delivery, hexosylceramide (d18:2/24:0), ceramide (d18.0/24.1) and serine, with an AUC for all predictors combined for low birth weight (≤2500grams) of 0.88 (95%CI: 0.75-1.005, p<0.001). CONCLUSIONS PCOS pregnancies resulted in babies with a lower birth weight, marked by a unique metabolic signature that was enriched with specific triglycerides and unsaturated fatty acids. The functional significance of these associations needs further investigation.
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Affiliation(s)
- Ilhame Diboun
- College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | - Manjunath Ramanjaneya
- Qatar Metabolic Institute, Hamad Medical Corporation, Doha, Qatar
- Translational Research Institute, Hamad Medical Corporation, Doha, Qatar
| | - Lina Ahmed
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
| | - Mohammed Bashir
- Qatar Metabolic Institute, Hamad Medical Corporation, Doha, Qatar
| | - Alexandra E Butler
- Diabetes Research Center (DRC), Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha, Qatar
| | - Omar Albagha
- College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Doha, Qatar
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Stephen L Atkin
- Post Graduate Studies and Research, Royal College of Surgeons in Ireland Bahrain, Adliya, Bahrain
| | - Nayef A Mazloum
- Department of Microbiology and Immunology, Weill Cornell Medicine-Qatar, Qatar Foundation, Doha, Qatar
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Diboun I, Ramanjaneya M, Majeed Y, Ahmed L, Bashir M, Butler AE, Abou-Samra AB, Atkin SL, Mazloum NA, Elrayess MA. Metabolic profiling of pre-gestational and gestational diabetes mellitus identifies novel predictors of pre-term delivery. J Transl Med 2020; 18:366. [PMID: 32972433 PMCID: PMC7517617 DOI: 10.1186/s12967-020-02531-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 09/15/2020] [Indexed: 12/23/2022] Open
Abstract
Background Pregnant women with gestational diabetes mellitus (GDM) or type 2 diabetes mellitus (T2DM) are at increased risks of pre-term labor, hypertension and preeclampsia. In this study, metabolic profiling of blood samples collected from GDM, T2DM and control pregnant women was undertaken to identify potential diagnostic biomarkers in GDM/T2DM and compared to pregnancy outcome. Methods Sixty-seven pregnant women (21 controls, 32 GDM, 14 T2DM) in their second trimester underwent targeted metabolomics of plasma samples using tandem mass spectrometry with the Biocrates MxP® Quant 500 Kit. Linear regression models were used to identify the metabolic signature of GDM and T2DM, followed by generalized linear model (GLMNET) and Receiver Operating Characteristic (ROC) analysis to determine best predictors of GDM, T2DM and pre-term labor. Results The gestational age at delivery was 2 weeks earlier in T2DM compared to GDM and controls and correlated negatively with maternal HbA1C and systolic blood pressure and positively with serum albumin. Linear regression models revealed elevated glutamate and branched chain amino acids in GDM + T2DM group compared to controls. Regression models also revealed association of lower levels of triacylglycerols and diacylglycerols containing oleic and linoleic fatty acids with pre-term delivery. A generalized linear model ROC analyses revealed that that glutamate is the best predictors of GDM compared to controls (area under curve; AUC = 0.81). The model also revealed that phosphatidylcholine diacyl C40:2, arachidonic acid, glycochenodeoxycholic acid, and phosphatidylcholine acyl-alkyl C34:3 are the best predictors of GDM + T2DM compared to controls (AUC = 0.90). The model also revealed that the triacylglycerols C17:2/36:4 and C18:1/34:1 are the best predictors of pre-term delivery (≤ 37 weeks) (AUC = 0.84). Conclusions This study highlights the metabolite alterations in women in their second trimester with diabetes mellitus and identifies predictive indicators of pre-term delivery. Future studies to confirm these associations in other cohorts and investigate their functional relevance and potential utilization for targeted therapies are warranted.
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Affiliation(s)
| | - Manjunath Ramanjaneya
- Qatar Metabolic Institute, Hamad Medical Corporation, Doha, Qatar.,Translational Research Institute, Hamad Medical Corporation, Doha, Qatar
| | | | - Lina Ahmed
- Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Mohammed Bashir
- Qatar Metabolic Institute, Hamad Medical Corporation, Doha, Qatar
| | - Alexandra E Butler
- Diabetes Research Center (DRC), Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), PO Box 34110, Doha, Qatar
| | | | - Stephen L Atkin
- Royal College of Surgeons in Ireland Bahrain, Adliya, Kingdom of Bahrain
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Al-Sulaiti H, Diboun I, Agha MV, Mohamed FFS, Atkin S, Dömling AS, Elrayess MA, Mazloum NA. Metabolic signature of obesity-associated insulin resistance and type 2 diabetes. J Transl Med 2019; 17:348. [PMID: 31640727 PMCID: PMC6805293 DOI: 10.1186/s12967-019-2096-8] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/11/2019] [Indexed: 12/17/2022] Open
Abstract
Background Obesity is associated with an increased risk of insulin resistance and type 2 diabetes mellitus (T2DM). However, some obese individuals maintain their insulin sensitivity and exhibit a lower risk of associated comorbidities. The underlying metabolic pathways differentiating obese insulin sensitive (OIS) and obese insulin resistant (OIR) individuals remain unclear. Methods In this study, 107 subjects underwent untargeted metabolomics of serum samples using the Metabolon platform. Thirty-two subjects were lean controls whilst 75 subjects were obese including 20 OIS, 41 OIR, and 14 T2DM individuals. Results Our results showed that phospholipid metabolites including choline, glycerophosphoethanolamine and glycerophosphorylcholine were significantly altered from OIS when compared with OIR and T2DM individuals. Furthermore, our data confirmed changes in metabolic markers of liver disease, vascular disease and T2DM, such as 3-hydroxymyristate, dimethylarginine and 1,5-anhydroglucitol, respectively. Conclusion This pilot data has identified phospholipid metabolites as potential novel biomarkers of obesity-associated insulin sensitivity and confirmed the association of known metabolites with increased risk of obesity-associated insulin resistance, with possible diagnostic and therapeutic applications. Further studies are warranted to confirm these associations in prospective cohorts and to investigate their functionality.
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Affiliation(s)
- Haya Al-Sulaiti
- Department of Drug Design, University of Groningen, A. Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Ilhame Diboun
- Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | | | | | - Stephen Atkin
- Weill Cornell Medicine-Qatar, Doha, Qatar.,Royal College of Surgeons, Ireland, Bahrain
| | - Alex S Dömling
- Department of Drug Design, University of Groningen, A. Deusinglaan 1, 9713 AV, Groningen, The Netherlands
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Gandra UR, Sinopoli A, Moncho S, NandaKumar M, Ninković DB, Zarić SD, Sohail M, Al-Meer S, Brothers EN, Mazloum NA, Al-Hashimi M, Bazzi HS. Green Light-Responsive CO-Releasing Polymeric Materials Derived from Ring-Opening Metathesis Polymerization. ACS Appl Mater Interfaces 2019; 11:34376-34384. [PMID: 31490644 DOI: 10.1021/acsami.9b12628] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Carbon monoxide (CO) is an important biological gasotransmitter in living cells. Precise spatial and temporal control over release of CO is a major requirement for clinical application. To date, the most reported carbon monoxide releasing materials use expensive fabrication methods and require harmful and poorly designed tissue-penetrating UV irradiation to initiate the CO release precisely at infected sites. Herein, we report the first example of utilizing a green light-responsive CO-releasing polymer P synthesized via ring-opening metathesis polymerization. Both monomer M and polymer P were very stable under dark conditions and CO release was effectively triggered using minimal power and low energy wavelength irradiation (550 nm, ≤28 mW). Time-dependent density functional theory (TD-DFT) calculations were carried out to simulate the electronic transition and insight into the nature of the excitations for both L and M. TD-DFT calculations indicate that the absorption peak of M is mainly due to the excitation of the seventh singlet excited state, S7. Furthermore, stretchable materials using polytetrafluoroethylene (PTFE) strips based on P were fabricated to afford P-PTFE, which can be used as a simple, inexpensive, and portable CO storage bandage. Insignificant cytotoxicity as well as cell permeability was found for M and P against human embryonic kidney cells.
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Affiliation(s)
- Upendar Reddy Gandra
- Department of Chemistry , Texas A&M University at Qatar , P.O. Box 23874, Doha , Qatar
| | - Alessandro Sinopoli
- Qatar Environmental & Energy Research Institute , Hamad Bin Khalifa University , P.O. Box 34110, Doha , Qatar
| | - Salvador Moncho
- Department of Chemistry , Texas A&M University at Qatar , P.O. Box 23874, Doha , Qatar
| | - Manjula NandaKumar
- Department of Microbiology and Immunology , Weill Cornell Medicine-Qatar , P.O. Box 24144, Doha , Qatar
| | - Dragan B Ninković
- Department of Chemistry , Texas A&M University at Qatar , P.O. Box 23874, Doha , Qatar
- Innovation Center of Faculty of Chemistry , Studentski trg 12-16 , 11000 Belgrade , Serbia
| | - Snežana D Zarić
- Department of Chemistry , Texas A&M University at Qatar , P.O. Box 23874, Doha , Qatar
- Faculty of Chemistry , Belgrade University , Studentski trg 12-16 , 11000 Belgrade , Serbia
| | - Muhammad Sohail
- Qatar Environmental & Energy Research Institute , Hamad Bin Khalifa University , P.O. Box 34110, Doha , Qatar
| | | | - Edward N Brothers
- Department of Chemistry , Texas A&M University at Qatar , P.O. Box 23874, Doha , Qatar
| | - Nayef A Mazloum
- Department of Microbiology and Immunology , Weill Cornell Medicine-Qatar , P.O. Box 24144, Doha , Qatar
| | - Mohammed Al-Hashimi
- Department of Chemistry , Texas A&M University at Qatar , P.O. Box 23874, Doha , Qatar
| | - Hassan S Bazzi
- Department of Chemistry , Texas A&M University at Qatar , P.O. Box 23874, Doha , Qatar
- Department of Materials Science & Engineering , Texas A&M University , 209 Reed McDonald Building , 77843-3003 College Station , Texas , United States
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Helaleh M, Diboun I, Al-Tamimi N, Al-Sulaiti H, Al-Emadi M, Madani A, Mazloum NA, Latiff A, Elrayess MA. Association of polybrominated diphenyl ethers in two fat compartments with increased risk of insulin resistance in obese individuals. Chemosphere 2018; 209:268-276. [PMID: 29933163 DOI: 10.1016/j.chemosphere.2018.06.108] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/06/2018] [Accepted: 06/15/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Polybrominated diphenyl ethers (PBDEs), a widely utilized class of flame retardants in various commercial products, represent a prominent source of environmental contaminants. PBDEs tend to accumulate in adipose tissue, potentially altering the function of this endocrine organ and increasing risk of insulin resistance. The aim of this study was to compare levels of PBDEs in adipose tissues from two metabolically distinct obese groups; the insulin sensitive (IS) and the insulin resistant (IR). METHODS Levels of 28 PBDE congeners were assessed in subcutaneous and omental adipose tissues from 34 obese Qatari individuals (11 IS and 23 IR) using gas chromatography (Trace GC Ultra) coupled to a TSQ Quantum triple Quadrupole mass spectrometer. Correlations of identified PBDEs and mediators of metabolic disease were established and effects of PBDEs treatment on insulin signaling in primary omental preadipocytes were determined. RESULTS Out of 22 detectable PBDEs in subcutaneous and omental adipose tissues, PBDEs 28, 47, 99 and 153 were predominant in omental adipose tissues from obese Qatari subjects. PBDEs 99, 28, and 47 were significantly higher in IR individuals compared to their IS counterparts. Significant positive correlations were identified between PBDEs 28 and 99 in the omental tissues and with fasting insulin levels. When considering PBDEs congeners, penta congeners were also higher in IR compared to IS individuals, while no significant differences were detected in mono, tri, tertra, hexa, hepta and octa congeners between the two studied groups. Treatment of human omental preadipocytes from insulin sensitive individuals with PBDE28 caused inhibition of phosphorylation of GSK3 α/β (Ser21/Ser9), mTOR (Ser2448), p70 S6 kinase (Thr389) and S6 ribosomal protein (Ser235/Ser236) and activation of PTEN (Ser380) phosphorylation, suggesting inhibition of insulin signaling. CONCLUSION This pilot data suggests that accumulation of specific PBDEs in human adipose tissues is associated with insulin resistance in obese individuals. Further investigation of the functional role of PBDEs in the pathology of insulin resistance should help developing therapeutic strategies targeting obese individuals at higher risk.
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Affiliation(s)
- Murad Helaleh
- Anti Doping Laboratory Qatar, Sports City, Doha, Qatar.
| | - Ilhame Diboun
- Department of Economics, Mathematics and Statistics, Birkbeck, University of London, London WC1E 7HX, UK.
| | | | | | | | - Aishah Madani
- Microbiology and Immunology, Weill Cornell Medicine-Qatar, Doha, Qatar.
| | - Nayef A Mazloum
- Microbiology and Immunology, Weill Cornell Medicine-Qatar, Doha, Qatar.
| | - Aishah Latiff
- Anti Doping Laboratory Qatar, Sports City, Doha, Qatar.
| | - Mohamed A Elrayess
- Anti Doping Laboratory Qatar, Sports City, Doha, Qatar; Division of Medicine, University College London, London, UK.
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Almuraikhy S, Kafienah W, Bashah M, Diboun I, Jaganjac M, Al-Khelaifi F, Abdesselem H, Mazloum NA, Alsayrafi M, Mohamed-Ali V, Elrayess MA. Interleukin-6 induces impairment in human subcutaneous adipogenesis in obesity-associated insulin resistance. Diabetologia 2016; 59:2406-2416. [PMID: 27342408 PMCID: PMC5506102 DOI: 10.1007/s00125-016-4031-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 06/02/2016] [Indexed: 12/22/2022]
Abstract
AIMS/HYPOTHESIS A subset of obese individuals remains insulin sensitive by mechanisms as yet unclear. The hypothesis that maintenance of normal subcutaneous (SC) adipogenesis accounts, at least partially, for this protective phenotype and whether it can be abrogated by chronic exposure to IL-6 was investigated. METHODS Adipose tissue biopsies were collected from insulin-sensitive (IS) and insulin-resistant (IR) individuals undergoing weight-reduction surgery. Adipocyte size, pre-adipocyte proportion of stromal vascular fraction (SVF)-derived cells, adipogenic capacity and gene expression profiles of isolated pre-adipocytes were determined, along with local in vitro IL-6 secretion. Adipogenic capacity was further assessed in response to exogenous IL-6 application. RESULTS Despite being equally obese, IR individuals had significantly lower plasma leptin and adiponectin levels and higher IL-6 levels compared with age-matched IS counterparts. Elevated systemic IL-6 in IR individuals was associated with hyperplasia of adipose tissue-derived SVF cells, despite higher frequency of hypertrophied adipocytes. SC pre-adipocytes from these tissues exhibited lower adipogenic capacity accompanied by downregulation of PPARγ (also known as PPARG) and CEBPα (also known as CEBPA) and upregulation of GATA3 expression. Impaired adipogenesis in IR individuals was further associated with increased adipose secretion of IL-6. Treatment of IS-derived SC pre-adipocytes with IL-6 reduced their adipogenic capacity to levels of the IR group. CONCLUSIONS/INTERPRETATION Obesity-associated insulin resistance is marked by impaired SC adipogenesis, mediated, at least in a subset of individuals, by elevated local levels of IL-6. Understanding the molecular mechanisms underlying reduced adipogenic capacity in IR individuals could help target appropriate therapeutic strategies aimed at those at greatest risk of insulin resistance and type 2 diabetes mellitus.
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Affiliation(s)
- Shamma Almuraikhy
- Anti-Doping Lab Qatar, Sports City Road, P.O. Box 27775, Doha, Qatar
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Wael Kafienah
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Moataz Bashah
- Bariatric and Metabolic Surgery, Hamad Medical Corporation, Doha, Qatar
| | - Ilhame Diboun
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Doha, Qatar
| | - Morana Jaganjac
- Anti-Doping Lab Qatar, Sports City Road, P.O. Box 27775, Doha, Qatar
| | | | - Houari Abdesselem
- Microbiology and Immunology, Weill Cornell Medicine Qatar, Doha, Qatar
| | - Nayef A Mazloum
- Microbiology and Immunology, Weill Cornell Medicine Qatar, Doha, Qatar
| | | | - Vidya Mohamed-Ali
- Anti-Doping Lab Qatar, Sports City Road, P.O. Box 27775, Doha, Qatar
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10
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Abdesselem H, Madani A, Hani A, Al-Noubi M, Goswami N, Ben Hamidane H, Billing AM, Pasquier J, Bonkowski MS, Halabi N, Dalloul R, Sheriff MZ, Mesaeli N, ElRayess M, Sinclair DA, Graumann J, Mazloum NA. SIRT1 Limits Adipocyte Hyperplasia through c-Myc Inhibition. J Biol Chem 2015; 291:2119-35. [PMID: 26655722 PMCID: PMC4732199 DOI: 10.1074/jbc.m115.675645] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Indexed: 01/14/2023] Open
Abstract
The expansion of fat mass in the obese state is due to increased adipocyte hypertrophy and hyperplasia. The molecular mechanism that drives adipocyte hyperplasia remains unknown. The NAD(+)-dependent protein deacetylase sirtuin 1 (SIRT1), a key regulator of mammalian metabolism, maintains proper metabolic functions in many tissues, counteracting obesity. Here we report that differentiated adipocytes are hyperplastic when SIRT1 is knocked down stably in mouse 3T3-L1 preadipocytes. This phenotype is associated with dysregulated adipocyte metabolism and enhanced inflammation. We also demonstrate that SIRT1 is a key regulator of proliferation in preadipocytes. Quantitative proteomics reveal that the c-Myc pathway is altered to drive enhanced proliferation in SIRT1-silenced 3T3-L1 cells. Moreover, c-Myc is hyperacetylated, levels of p27 are reduced, and cyclin-dependent kinase 2 (CDK2) is activated upon SIRT1 reduction. Remarkably, differentiating SIRT1-silenced preadipocytes exhibit enhanced mitotic clonal expansion accompanied by reduced levels of p27 as well as elevated levels of CCAAT/enhancer-binding protein β (C/EBPβ) and c-Myc, which is also hyperacetylated. c-Myc activation and enhanced proliferation phenotype are also found to be SIRT1-dependent in proliferating mouse embryonic fibroblasts and differentiating human SW872 preadipocytes. Reducing both SIRT1 and c-Myc expression in 3T3-L1 cells simultaneously does not induce the adipocyte hyperplasia phenotype, confirming that SIRT1 controls adipocyte hyperplasia through c-Myc regulation. A better understanding of the molecular mechanisms of adipocyte hyperplasia will open new avenues toward understanding obesity.
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Affiliation(s)
| | - Aisha Madani
- From the Departments of Microbiology and Immunology
| | - Ahmad Hani
- From the Departments of Microbiology and Immunology
| | | | | | | | | | - Jennifer Pasquier
- Genetic Medicine, Weill Cornell Medicine Qatar, Qatar Foundation, Education City, P.O. Box 24144, Doha, Qatar
| | - Michael S Bonkowski
- the Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, and
| | - Najeeb Halabi
- Genetic Medicine, Weill Cornell Medicine Qatar, Qatar Foundation, Education City, P.O. Box 24144, Doha, Qatar
| | | | | | | | - Mohamed ElRayess
- the Life Sciences Research Division, Anti-Doping Lab Qatar, P.O. Box 27775, Doha, Qatar
| | - David A Sinclair
- the Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, and
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11
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Abstract
Brh2, the BRCA2 ortholog in Ustilago maydis, enables recombinational repair of DNA by controlling Rad51 and is in turn regulated by Dss1. Interplay with Rad51 is conducted via the BRC element located in the N-terminal region of the protein and through an unrelated domain, CRE, at the C terminus. Mutation in either BRC or CRE severely reduces functional activity, but repair deficiency of the brh2 mutant can be complemented by expressing BRC and CRE on different molecules. This intermolecular complementation is dependent upon the presence of Dss1. Brh2 molecules associate through the region overlapping with the Dss1-interacting domain to form at least dimer-sized complexes, which in turn, can be dissociated by Dss1 to monomer. We propose that cooperation between BRC and CRE domains and the Dss1-provoked dissociation of Brh2 complexes are requisite features of Brh2's molecular mechanism.
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Affiliation(s)
- Qingwen Zhou
- Department of Microbiology and Immunology, Cornell University Weill Medical College, 1300 York Avenue, New York, NY 10021, USA
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