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Sen B, Xie Z, Thomas MD, Pattenden SG, Howard S, McGrath C, Styner M, Uzer G, Furey TS, Rubin J. Nuclear actin structure regulates chromatin accessibility. Nat Commun 2024; 15:4095. [PMID: 38750021 PMCID: PMC11096319 DOI: 10.1038/s41467-024-48580-y] [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: 08/28/2023] [Accepted: 05/07/2024] [Indexed: 05/18/2024] Open
Abstract
Polymerized β-actin may provide a structural basis for chromatin accessibility and actin transport into the nucleus can guide mesenchymal stem cell (MSC) differentiation. Using MSC, we show that using CK666 to inhibit Arp2/3 directed secondary actin branching results in decreased nuclear actin structure, and significantly alters chromatin access measured with ATACseq at 24 h. The ATAC-seq results due to CK666 are distinct from those caused by cytochalasin D (CytoD), which enhances nuclear actin structure. In addition, nuclear visualization shows Arp2/3 inhibition decreases pericentric H3K9me3 marks. CytoD, alternatively, induces redistribution of H3K27me3 marks centrally. Such alterations in chromatin landscape are consistent with differential gene expression associated with distinctive differentiation patterns. Further, knockdown of the non-enzymatic monomeric actin binding protein, Arp4, leads to extensive chromatin unpacking, but only a modest increase in transcription, indicating an active role for actin-Arp4 in transcription. These data indicate that dynamic actin remodeling can regulate chromatin interactions.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Michelle D Thomas
- Division of Chemical Biology and Medicinal Chemistry, Center for Integrative Chemical Biology and Drug Discovery, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Samantha G Pattenden
- Division of Chemical Biology and Medicinal Chemistry, Center for Integrative Chemical Biology and Drug Discovery, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sean Howard
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Cody McGrath
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Gunes Uzer
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Terrence S Furey
- Departments of Genetics and Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA.
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McGrath C, Little-Letsinger SE, Pagnotti GM, Sen B, Xie Z, Uzer G, Uzer GB, Zong X, Styner MA, Rubin J, Styner M. Diet-Stimulated Marrow Adiposity Fails to Worsen Early, Age-Related Bone Loss. Obes Facts 2024; 17:145-157. [PMID: 38224679 PMCID: PMC10987189 DOI: 10.1159/000536159] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 01/04/2024] [Indexed: 01/17/2024] Open
Abstract
INTRODUCTION Longitudinal effect of diet-induced obesity on bone is uncertain. Prior work showed both no effect and a decrement in bone density or quality when obesity begins prior to skeletal maturity. We aimed to quantify long-term effects of obesity on bone and bone marrow adipose tissue (BMAT) in adulthood. METHODS Skeletally mature, female C57BL/6 mice (n = 70) aged 12 weeks were randomly allocated to low-fat diet (LFD; 10% kcal fat; n = 30) or high-fat diet (HFD; 60% kcal fat; n = 30), with analyses at 12, 15, 18, and 24 weeks (n = 10/group). Tibial microarchitecture was analyzed by µCT, and volumetric BMAT was quantified via 9.4T MRI/advanced image analysis. Histomorphometry of adipocytes and osteoclasts, and qPCR were performed. RESULTS Body weight and visceral white adipose tissue accumulated in response to HFD started in adulthood. Trabecular bone parameters declined with advancing experimental age. BV/TV declined 22% in LFD (p = 0.0001) and 17% in HFD (p = 0.0022) by 24 weeks. HFD failed to appreciably alter BV/TV and had negligible impact on other microarchitecture parameters. Both dietary intervention and age accounted for variance in BMAT, with regional differences: distal femoral BMAT was more responsive to diet, while proximal femoral BMAT was more attenuated by age. BMAT increased 60% in the distal metaphysis in HFD at 18 and 24 weeks (p = 0.0011). BMAT in the proximal femoral diaphysis, unchanged by diet, decreased 45% due to age (p = 0.0002). Marrow adipocyte size via histomorphometry supported MRI quantification. Osteoclast number did not differ between groups. Tibial qPCR showed attenuation of some adipose, metabolism, and bone genes. A regulator of fatty acid β-oxidation, cytochrome C (CYCS), was 500% more abundant in HFD bone (p < 0.0001; diet effect). CYCS also increased due to age, but to a lesser extent. HFD mildly increased OCN, TRAP, and SOST. CONCLUSIONS Long-term high fat feeding after skeletal maturity, despite upregulation of visceral adiposity, body weight, and BMAT, failed to attenuate bone microarchitecture. In adulthood, we found aging to be a more potent regulator of microarchitecture than diet-induced obesity.
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Affiliation(s)
- Cody McGrath
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah E. Little-Letsinger
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gabriel M. Pagnotti
- Department of Endocrine, Neoplasia and Hormonal Disorders, MD Anderson Cancer Center, Houston, TX, USA
| | - Buer Sen
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Zhihui Xie
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gunes Uzer
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Guniz B. Uzer
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Xiaopeng Zong
- Radiology and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Martin A. Styner
- Departments of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Psychiatry, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Janet Rubin
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Maya Styner
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Bhaskar P, Panidapu N, Thomas D, Varghese R, Sen B. 'Pseudo-curare clefts' secondary to an aneurysmal right pulmonary artery. Anaesth Rep 2024; 12:e12295. [PMID: 38680851 PMCID: PMC11053367 DOI: 10.1002/anr3.12295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2024] [Indexed: 05/01/2024] Open
Affiliation(s)
- P. Bhaskar
- Department of Paediatric Cardiac Anaesthesia and Intensive CareMohammed bin Khalifa bin Salman Al Khalifa Specialist Cardiac Centre HospitalAwaliBahrain
| | - N. Panidapu
- Department of Cardiac AnesthesiaAmrita Institute of Medical SciencesKochiIndia
| | - D. Thomas
- Department of Cardiac AnesthesiaAmrita Institute of Medical SciencesKochiIndia
| | - R. Varghese
- Department of Paediatric Cardiac SurgeryMohammed bin Khalifa bin Salman Al Khalifa Specialist Cardiac Centre HospitalAwaliBahrain
| | - B. Sen
- Department of Cardiac AnesthesiaAmrita Institute of Medical SciencesKochiIndia
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Sen B, Xie Z, Howard S, Styner M, van Wijnen AJ, Uzer G, Rubin J. Mechanically Induced Nuclear Shuttling of β-Catenin Requires Co-transfer of Actin. Stem Cells 2022; 40:423-434. [PMID: 35278073 PMCID: PMC9633329 DOI: 10.1093/stmcls/sxac006] [Citation(s) in RCA: 6] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 01/27/2022] [Indexed: 11/15/2022]
Abstract
Mesenchymal stem cells (MSCs) respond to environmental forces with both cytoskeletal re-structuring and activation of protein chaperones of mechanical information, β-catenin, and yes-associated protein 1 (YAP1). To function, MSCs must differentiate between dynamic forces such as cyclic strains of extracellular matrix due to physical activity and static strains due to ECM stiffening. To delineate how MSCs recognize and respond differently to both force types, we compared effects of dynamic (200 cycles × 2%) and static (1 × 2% hold) strain on nuclear translocation of β-catenin and YAP1 at 3 hours after force application. Dynamic strain induced nuclear accumulation of β-catenin, and increased cytoskeletal actin structure and cell stiffness, but had no effect on nuclear YAP1 levels. Critically, both nuclear actin and nuclear stiffness increased along with dynamic strain-induced β-catenin transport. Augmentation of cytoskeletal structure using either static strain or lysophosphatidic acid did not increase nuclear content of β-catenin or actin, but induced robust nuclear increase in YAP1. As actin binds β-catenin, we considered whether β-catenin, which lacks a nuclear localization signal, was dependent on actin to gain entry to the nucleus. Knockdown of cofilin-1 (Cfl1) or importin-9 (Ipo9), which co-mediate nuclear transfer of G-actin, prevented dynamic strain-mediated nuclear transfer of both β-catenin and actin. In sum, dynamic strain induction of actin re-structuring promotes nuclear transport of G-actin, concurrently supporting nuclear access of β-catenin via mechanisms used for actin transport. Thus, dynamic and static strain activate alternative mechanoresponses reflected by differences in the cellular distributions of actin, β-catenin, and YAP1.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Sean Howard
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Andre J van Wijnen
- Department of Biochemistry, University of Vermont Medical School, Burlington, VT, USA
| | - Gunes Uzer
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Janet Rubin
- Corresponding author: Janet Rubin, Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
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Xie Z, McGrath C, Sankaran J, Styner M, Little-Letsinger S, Dudakovic A, van Wijnen AJ, Rubin J, Sen B. Low-Dose Tamoxifen Induces Significant Bone Formation in Mice. JBMR Plus 2021; 5:e10450. [PMID: 33778320 PMCID: PMC7990151 DOI: 10.1002/jbm4.10450] [Citation(s) in RCA: 9] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 12/31/2022] Open
Abstract
Use of the selective estrogen receptor modulator Tamoxifen (TAM) is a mainstay to induce conditional expression of Cre recombinase in transgenic laboratory mice. To excise β‐cateninfl/fl in 28‐day‐old male and female Prrx1‐CreER/β‐cateninfl/fl mice (C57BL/6), we utilized TAM at 150 mg/kg; despite β‐catenin knockout in MSC, we found a significant increase in trabecular and cortical bone volume in all genders. Because TAM was similarly anabolic in KO and control mice, we investigated a dose effect on bone formation by treating wild‐type mice (WT C57BL/6, 4 weeks) with TAM (total dose 0, 20, 40, 200 mg/kg via four injections). TAM increased bone in a dose‐dependent manner analyzed by micro–computed tomography (μCT), which showed that, compared to control, 20 mg/kg TAM increased femoral bone volume fraction (bone volume/total volume [BV/TV]) (21.6% ± 1.5% to 33% ± 2.5%; 153%, p < 0.005). With TAM 40 mg/kg and 200 mg/kg, BV/TV increased to 48.1% ± 4.4% (223%, p < 0.0005) and 58% ± 3.8% (269%, p < 0.0001) respectively, compared to control. Osteoblast markers increased with 200 mg/kg TAM: Dlx5 (224%, p < 0.0001), Alp (166%, p < 0.0001), Bglap (223%, p < 0.0001), and Sp7 (228%, p < 0.0001). Osteoclasts per bone surface (Oc#/BS) nearly doubled at the lowest TAM dose (20 mg/kg), but decreased to <20% control with 200 mg/kg TAM. Our data establish that use of TAM at even very low doses to excise a floxed target in postnatal mice has profound effects on trabecular and cortical bone formation. As such, TAM treatment is a major confounder in the interpretation of bone phenotypes in conditional gene knockout mouse models. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Zhihui Xie
- Department of Medicine University of North Carolina Chapel Hill NC USA
| | - Cody McGrath
- Department of Medicine University of North Carolina Chapel Hill NC USA
| | - Jeyantt Sankaran
- Department of Medicine University of North Carolina Chapel Hill NC USA
| | - Maya Styner
- Department of Medicine University of North Carolina Chapel Hill NC USA
| | | | - Amel Dudakovic
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology Mayo Clinic Rochester MN USA
| | - Andre J van Wijnen
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology Mayo Clinic Rochester MN USA
| | - Janet Rubin
- Department of Medicine University of North Carolina Chapel Hill NC USA
| | - Buer Sen
- Department of Medicine University of North Carolina Chapel Hill NC USA
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McGrath C, Little-Letsinger SE, Sankaran JS, Sen B, Xie Z, Styner MA, Zong X, Chen W, Rubin J, Klett EL, Coleman RA, Styner M. Exercise Increases Bone in SEIPIN Deficient Lipodystrophy, Despite Low Marrow Adiposity. Front Endocrinol (Lausanne) 2021; 12:782194. [PMID: 35145475 PMCID: PMC8822583 DOI: 10.3389/fendo.2021.782194] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/20/2021] [Indexed: 01/12/2023] Open
Abstract
Exercise, typically beneficial for skeletal health, has not yet been studied in lipodystrophy, a condition characterized by paucity of white adipose tissue, with eventual diabetes, and steatosis. We applied a mouse model of global deficiency of Bscl2 (SEIPIN), required for lipid droplet formation. Male twelve-week-old B6 knockouts (KO) and wild type (WT) littermates were assigned six-weeks of voluntary, running exercise (E) versus non-exercise (N=5-8). KO weighed 14% less than WT (p=0.01) and exhibited an absence of epididymal adipose tissue; KO liver Plin1 via qPCR was 9-fold that of WT (p=0.04), consistent with steatosis. Bone marrow adipose tissue (BMAT), unlike white adipose, was measurable, although 40.5% lower in KO vs WT (p=0.0003) via 9.4T MRI/advanced image analysis. SEIPIN ablation's most notable effect marrow adiposity was in the proximal femoral diaphysis (-56% KO vs WT, p=0.005), with relative preservation in KO-distal-femur. Bone via μCT was preserved in SEIPIN KO, though some quality parameters were attenuated. Running distance, speed, and time were comparable in KO and WT. Exercise reduced weight (-24% WT-E vs WT p<0.001) but not in KO. Notably, exercise increased trabecular BV/TV in both (+31%, KO-E vs KO, p=0.004; +14%, WT-E vs WT, p=0.006). The presence and distribution of BMAT in SEIPIN KO, though lower than WT, is unexpected and points to a uniqueness of this depot. That trabecular bone increases were achievable in both KO and WT, despite a difference in BMAT quantity/distribution, points to potential metabolic flexibility during exercise-induced skeletal anabolism.
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Affiliation(s)
- Cody McGrath
- Department of Medicine, Division of Endocrinology & Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Sarah E. Little-Letsinger
- Department of Medicine, Division of Endocrinology & Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Jeyantt Srinivas Sankaran
- Department of Medicine, Division of Endocrinology & Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Buer Sen
- Department of Medicine, Division of Endocrinology & Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Zhihui Xie
- Department of Medicine, Division of Endocrinology & Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Martin A. Styner
- Department of Psychiatry, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Xiaopeng Zong
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Weiqin Chen
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Janet Rubin
- Department of Medicine, Division of Endocrinology & Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- North Carolina Diabetes Research Center (NCDRC), Chapel Hill, NC, United States
| | - Eric L. Klett
- Department of Medicine, Division of Endocrinology & Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- North Carolina Diabetes Research Center (NCDRC), Chapel Hill, NC, United States
- Department of Nutrition, Gillings School of Global Public Health, UNC, Chapel Hill, NC, United States
| | - Rosalind A. Coleman
- Department of Nutrition, Gillings School of Global Public Health, UNC, Chapel Hill, NC, United States
| | - Maya Styner
- Department of Medicine, Division of Endocrinology & Metabolism, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- North Carolina Diabetes Research Center (NCDRC), Chapel Hill, NC, United States
- *Correspondence: Maya Styner,
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Sen B, Paradise CR, Xie Z, Sankaran J, Uzer G, Styner M, Meyer M, Dudakovic A, van Wijnen AJ, Rubin J. β-Catenin Preserves the Stem State of Murine Bone Marrow Stromal Cells Through Activation of EZH2. J Bone Miner Res 2020; 35:1149-1162. [PMID: 32022326 PMCID: PMC7295671 DOI: 10.1002/jbmr.3975] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 01/23/2020] [Accepted: 01/29/2020] [Indexed: 12/11/2022]
Abstract
During bone marrow stromal cell (BMSC) differentiation, both Wnt signaling and the development of a rigid cytoskeleton promote commitment to the osteoblastic over adipogenic lineage. β-catenin plays a critical role in the Wnt signaling pathway to facilitate downstream effects on gene expression. We show that β-catenin was additive with cytoskeletal signals to prevent adipogenesis, and β-catenin knockdown promoted adipogenesis even when the actin cytoskeleton was depolymerized. β-catenin also prevented osteoblast commitment in a cytoskeletal-independent manner, with β-catenin knockdown enhancing lineage commitment. Chromatin immunoprecipitation (ChIP)-sequencing demonstrated binding of β-catenin to the promoter of enhancer of zeste homolog 2 (EZH2), a key component of the polycomb repressive complex 2 (PRC2) complex that catalyzes histone methylation. Knockdown of β-catenin reduced EZH2 protein levels and decreased methylated histone 3 (H3K27me3) at osteogenic loci. Further, when EZH2 was inhibited, β-catenin's anti-differentiation effects were lost. These results indicate that regulating EZH2 activity is key to β-catenin's effects on BMSCs to preserve multipotentiality. © 2020 American Society for Bone and Mineral Research.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina Chapel Hill, Raleigh, NC, USA
| | - Christopher R Paradise
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA.,Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina Chapel Hill, Raleigh, NC, USA
| | - Jeyantt Sankaran
- Department of Medicine, University of North Carolina Chapel Hill, Raleigh, NC, USA
| | - Gunes Uzer
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Maya Styner
- Department of Medicine, University of North Carolina Chapel Hill, Raleigh, NC, USA
| | - Mark Meyer
- Department of Biochemistry, University of Wisconsin, Madison, WI, USA
| | - Amel Dudakovic
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Andre J van Wijnen
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA.,Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina Chapel Hill, Raleigh, NC, USA
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Abstract
ObjectivePhenylephrine, pseudoephedrine and ephedrine are the sympathomimetic drugs that have been used most commonly in oral preparations for the relief of nasal congestion. These drugs stimulate the central nervous system that is affected by the alpha and beta adrenergic agonism. Sympathomimetic agents used in the treatment of flu and common cold with ephedrine and pseudoephedrine are case reports. That the manic and psychotic episodes are triggered. In this article, we would like to present a bipolar manic disorder with two manic episodes and both of them triggered by influenza drugs.CaseA 25-year-old man patient was admitted to psychiatric outpatient clinic with increasing complaints such as increasing energy, speaking much, decreasing sleep, increasing the libido after using the flu drug that prescribed to him containing phenylephrine. Also, 2 years ago, he has manic attack triggered after the flu drug.DiscussionIn recent years the study of epilepsy and bipolar disorder in common suggests that bipolar disorder may affect the kindling phenomenon. In our case, two of reasons in the neurobiology of developing manic attacks the kindling phenomenon is likely to be effective. First, the possibility of using cold medicine containing ephedrine or pseudoephedrine in the first manic episode, in the second manic episode having spent the attack with FAQ stimulant effect of lower phenylephrine. Second, in the first episode after using the 5–6 tablets developing manic attacks. In the second attack to be triggered with just 2 doses may indicate the effect of kindling.Disclosure of interestThe authors have not supplied their declaration of competing interest.
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Sankaran JS, Sen B, Dudakovic A, Paradise CR, Perdue T, Xie Z, McGrath C, Styner M, Newberg J, Uzer G, van Wijnen AJ, Rubin J. Knockdown of formin mDia2 alters lamin B1 levels and increases osteogenesis in stem cells. Stem Cells 2020; 38:102-117. [PMID: 31648392 PMCID: PMC6993926 DOI: 10.1002/stem.3098] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [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: 01/31/2019] [Revised: 09/03/2019] [Accepted: 09/12/2019] [Indexed: 02/06/2023]
Abstract
Nuclear actin plays a critical role in mediating mesenchymal stem cell (MSC) fate commitment. In marrow-derived MSCs, the principal diaphanous-related formin Diaph3 (mDia2) is present in the nucleus and regulates intranuclear actin polymerization, whereas Diaph1 (mDia1) is localized to the cytoplasm and controls cytoplasmic actin polymerization. We here show that mDia2 can be used as a tool to query actin-lamin nucleoskeletal structure. Silencing mDia2 affected the nucleoskeletal lamin scaffold, altering nuclear morphology without affecting cytoplasmic actin cytoskeleton, and promoted MSC differentiation. Attempting to target intranuclear actin polymerization by silencing mDia2 led to a profound loss in lamin B1 nuclear envelope structure and integrity, increased nuclear height, and reduced nuclear stiffness without compensatory changes in other actin nucleation factors. Loss of mDia2 with the associated loss in lamin B1 promoted Runx2 transcription and robust osteogenic differentiation and suppressed adipogenic differentiation. Hence, mDia2 is a potent tool to query intranuclear actin-lamin nucleoskeletal structure, and its presence serves to retain multipotent stromal cells in an undifferentiated state.
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Affiliation(s)
- Jeyantt S. Sankaran
- Department of Medicine, University of North Carolina Chapel
Hill, Chapel Hill, North Carolina
| | - Buer Sen
- Department of Medicine, University of North Carolina Chapel
Hill, Chapel Hill, North Carolina
| | - Amel Dudakovic
- Department of Orthopedic Surgery and Biochemistry and
Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Christopher R. Paradise
- Graduate School of Biomedical Sciences and Center for
Regenerative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Tony Perdue
- Department of Biology, University of North Carolina Chapel
Hill, Chapel Hill, North Carolina
| | - Zhihui Xie
- Department of Medicine, University of North Carolina Chapel
Hill, Chapel Hill, North Carolina
| | - Cody McGrath
- Department of Medicine, University of North Carolina Chapel
Hill, Chapel Hill, North Carolina
| | - Maya Styner
- Department of Medicine, University of North Carolina Chapel
Hill, Chapel Hill, North Carolina
| | - Joshua Newberg
- Department of Mechanical and Biomedical Engineering, Boise
State University, Boise, Idaho
| | - Gunes Uzer
- Department of Mechanical and Biomedical Engineering, Boise
State University, Boise, Idaho
| | - Andre J. van Wijnen
- Department of Orthopedic Surgery and Biochemistry and
Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Janet Rubin
- Department of Medicine, University of North Carolina Chapel
Hill, Chapel Hill, North Carolina
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Paul GK, Karmoker KK, Sen B, Hussain MZ, Hasan MS, Khan MK. Risk Factors for Hypertension in Young Adults of Bangladesh. Mymensingh Med J 2020; 29:43-47. [PMID: 31915334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hypertension is a major public health challenge to population in socio-economic and epidemiological transition. It is a risk factor for cardiovascular mortality which accounts for 20-50 per cent of all deaths. Hypertension has been recognized among young adults more frequently in recent years. Data regarding hypertension in Bangladesh is often insufficient. The purpose of the study was to find out the risk factors of hypertension in young adults of Bangladesh. The study was conducted among 322 purposively selected young adults aged 20 to 49 years attending in the outpatient department of one public and five private hospitals of Mymensingh and Dhaka division of Bangladesh during the period of January 2018 to December 2018. More than half (54.4%) of the patients were at or below the age of 40 years. Mean age of the patients was 38.7±7.8 years and 58.7% were male. Maximum patients (87.6%) were married and with variable educational and occupational status. More than three fourth of the patients (76.7%) were from urban area whereas 14.3% from rural and 9.0% were from sub-urban area. Family history of hypertension was positive in 86.6% of patients. Blood pressure was categorized according to JNC 7. About half (49.4%) of the patients were stage I hypertensive; 22.4% were stage II hypertensive and 28.3% were pre-hypertensive. The major risk factor was tobacco smoking (46.0%), obesity (29.2%), dyslipidaemia (25.2%), high salt intake 21.8% and use of chewable tobacco (13.7%). Serum creatinine was found raised in 11.5%, cardiomegaly in 2.2% and concentric left ventricular hypertrophy in 18.6% of patients. In 38.5% patients hypertension was complicated affecting heart (27.0%) and kidney (11.5%). Common comorbidities were ischaemic heart diseases (20.5%) and diabetes mellitus (13.4%). Tobacco use, obesity, dyslipidaemia and high salt intake are the major modifiable risk factors found in hypertensive young adults. In addition to medication these factors should be addressed for prevention and effective control of hypertension.
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Affiliation(s)
- G K Paul
- Dr Gobinda Kanti Paul, Assistant Professor, Department of Cardiology, Mymensingh Medical College (MMC), Mymensingh, Bangladesh; E-mail:
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11
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McGrath C, Sankaran JS, Misaghian‐Xanthos N, Sen B, Xie Z, Styner MA, Zong X, Rubin J, Styner M. Exercise Degrades Bone in Caloric Restriction, Despite Suppression of Marrow Adipose Tissue (MAT). J Bone Miner Res 2020; 35:106-115. [PMID: 31509274 PMCID: PMC6980282 DOI: 10.1002/jbmr.3872] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [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: 02/26/2019] [Revised: 08/13/2019] [Accepted: 08/30/2019] [Indexed: 01/06/2023]
Abstract
Marrow adipose tissue (MAT) and its relevance to skeletal health during caloric restriction (CR) is unknown: It remains unclear whether exercise, which is anabolic to bone in a calorie-replete state, alters bone or MAT in CR. We hypothesized that response of bone and MAT to exercise in CR differs from the calorie-replete state. Ten-week-old female B6 mice fed a regular diet (RD) or 30% CR diet were allocated to sedentary (RD, CR, n = 10/group) or running exercise (RD-E, CR-E, n = 7/group). After 6 weeks, CR mice weighed 20% less than RD, p < 0.001; exercise did not affect weight. Femoral bone volume (BV) via 3D MRI was 20% lower in CR versus RD (p < 0.0001). CR was associated with decreased bone by μCT: Tb.Th was 16% less in CR versus RD, p < 0.003, Ct.Th was 5% less, p < 0.07. In CR-E, Tb.Th was 40% less than RD-E, p < 0.0001. Exercise increased Tb.Th in RD (+23% RD-E versus RD, p < 0.003) but failed to do so in CR. Cortical porosity increased after exercise in CR (+28%, p = 0.04), suggesting exercise during CR is deleterious to bone. In terms of bone fat, metaphyseal MAT/ BV rose 159% in CR versus RD, p = 0.003 via 3D MRI. Exercise decreased MAT/BV by 52% in RD, p < 0.05, and also suppressed MAT in CR (-121%, p = 0.047). Histomorphometric analysis of adipocyte area correlated with MAT by MRI (R2 = 0.6233, p < 0.0001). With respect to bone, TRAP and Sost mRNA were reduced in CR. Intriguingly, the repressed Sost in CR rose with exercise and may underlie the failure of CR-bone quantity to increase in response to exercise. Notably, CD36, a marker of fatty acid uptake, rose 4088% in CR (p < 0.01 versus RD), suggesting that basal increases in MAT during calorie restriction serve to supply local energy needs and are depleted during exercise with a negative impact on bone. © 2019 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.
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Affiliation(s)
- Cody McGrath
- Department of Medicine, Division of EndocrinologyUniversity of North CarolinaChapel HillNCUSA
| | - Jeyantt S Sankaran
- Department of Medicine, Division of EndocrinologyUniversity of North CarolinaChapel HillNCUSA
| | - Negin Misaghian‐Xanthos
- Department of Medicine, Division of EndocrinologyUniversity of North CarolinaChapel HillNCUSA
| | - Buer Sen
- Department of Medicine, Division of EndocrinologyUniversity of North CarolinaChapel HillNCUSA
| | - Zhihui Xie
- Department of Medicine, Division of EndocrinologyUniversity of North CarolinaChapel HillNCUSA
| | - Martin A Styner
- Department of Computer ScienceUniversity of North CarolinaChapel HillNCUSA
- Department of PsychiatryUniversity of North CarolinaChapel HillNCUSA
| | - Xiaopeng Zong
- Biomedical Research Imaging CenterUniversity of North CarolinaChapel HillNCUSA
| | - Janet Rubin
- Department of Medicine, Division of EndocrinologyUniversity of North CarolinaChapel HillNCUSA
| | - Maya Styner
- Department of Medicine, Division of EndocrinologyUniversity of North CarolinaChapel HillNCUSA
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12
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Samsonraj RM, Paradise CR, Dudakovic A, Sen B, Nair AA, Dietz AB, Deyle DR, Cool SM, Rubin J, van Wijnen AJ. Validation of Osteogenic Properties of Cytochalasin D by High-Resolution RNA-Sequencing in Mesenchymal Stem Cells Derived from Bone Marrow and Adipose Tissues. Stem Cells Dev 2018; 27:1136-1145. [PMID: 29882479 DOI: 10.1089/scd.2018.0037] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Differentiation of mesenchymal stromal/stem cells (MSCs) involves a series of molecular signals and gene transcription events required for attaining cell lineage commitment. Modulation of the actin cytoskeleton using cytochalasin D (CytoD) drives osteogenesis at early timepoints in bone marrow-derived MSCs and also initiates a robust osteogenic differentiation program in adipose tissue-derived MSCs. To understand the molecular basis for these pronounced effects on osteogenic differentiation, we investigated global changes in gene expression in CytoD-treated murine and human MSCs by high-resolution RNA-sequencing (RNA-seq) analysis. A three-way bioinformatic comparison between human adipose tissue-derived MSCs (hAMSCs), human bone marrow-derived MSCs (hBMSCs), and mouse bone marrow-derived MSCs (mBMSCs) revealed significant upregulation of genes linked to extracellular matrix organization, cell adhesion and bone metabolism. As anticipated, the activation of these differentiation-related genes is accompanied by a downregulation of nuclear and cell cycle-related genes presumably reflecting cytostatic effects of CytoD. We also identified eight novel CytoD activated genes-VGLL4, ARHGAP24, KLHL24, RCBTB2, BDH2, SCARF2, ACAD10, HEPH-which are commonly upregulated across the two species and tissue sources of our MSC samples. We selected the Hippo pathway-related VGLL4 gene, which encodes the transcriptional co-factor Vestigial-like 4, for further study because this pathway is linked to osteogenesis. VGLL4 small interfering RNA depletion reduces mineralization of hAMSCs during CytoD-induced osteogenic differentiation. Together, our RNA-seq analyses suggest that while the stimulatory effects of CytoD on osteogenesis are pleiotropic and depend on the biological state of the cell type, a small group of genes including VGLL4 may contribute to MSC commitment toward the bone lineage.
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Affiliation(s)
| | - Christopher R Paradise
- 2 Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic Graduate School of Biomedical Sciences , Mayo Clinic, Rochester, Minnesota.,3 Center for Regenerative Medicine, Mayo Clinic , Rochester, Minnesota
| | - Amel Dudakovic
- 1 Department of Orthopedic Surgery, Mayo Clinic , Rochester, Minnesota
| | - Buer Sen
- 4 Department of Medicine, University of North Carolina , Chapel Hill, North Carolina
| | - Asha A Nair
- 5 Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic , Rochester, Minnesota
| | - Allan B Dietz
- 6 Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota
| | - David R Deyle
- 7 Department of Medical Genetics, Mayo Clinic , Rochester, Minnesota
| | - Simon M Cool
- 8 Glycotherapeutics Group, Institute of Medical Biology , Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Janet Rubin
- 3 Center for Regenerative Medicine, Mayo Clinic , Rochester, Minnesota
| | - Andre J van Wijnen
- 1 Department of Orthopedic Surgery, Mayo Clinic , Rochester, Minnesota.,3 Center for Regenerative Medicine, Mayo Clinic , Rochester, Minnesota
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Uzer G, Bas G, Sen B, Xie Z, Birks S, Olcum M, McGrath C, Styner M, Rubin J. Sun-mediated mechanical LINC between nucleus and cytoskeleton regulates βcatenin nuclear access. J Biomech 2018; 74:32-40. [PMID: 29691054 PMCID: PMC5962429 DOI: 10.1016/j.jbiomech.2018.04.013] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [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: 01/30/2018] [Revised: 03/30/2018] [Accepted: 04/04/2018] [Indexed: 02/02/2023]
Abstract
βcatenin acts as a primary intracellular signal transducer for mechanical and Wnt signaling pathways to control cell function and fate. Regulation of βcatenin in the cytoplasm has been well studied but βcatenin nuclear trafficking and function remains unclear. In a previous study we showed that, in mesenchymal stem cells (MSC), mechanical blockade of adipogenesis relied on inhibition of βcatenin destruction complex element GSK3β (glycogen synthase kinase 3β) to increase nuclear βcatenin as well as the function of Linker of Cytoskeleton and Nucleoskeleton (LINC) complexes, suggesting that these two mechanisms may be linked. Here we show that shortly after inactivation of GSK3β due to either low intensity vibration (LIV), substrate strain or pharmacologic inhibition, βcatenin associates with the nucleoskeleton, defined as the insoluble nuclear fraction that provides structure to the integrated nuclear envelope, nuclear lamina and chromatin. Co-depleting LINC elements Sun-1 and Sun-2 interfered with both nucleoskeletal association and nuclear entry of βcatenin, resulting in decreased nuclear βcatenin levels. Our findings reveal that the insoluble structural nucleoskeleton actively participates in βcatenin dynamics. As the cytoskeleton transmits applied mechanical force to the nuclear surface to influence the nucleoskeleton and its LINC mediated interaction, our results suggest a pathway by which LINC mediated connectivity may play a role in signaling pathways that depend on nuclear access of βcatenin.
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Affiliation(s)
- Gunes Uzer
- Boise State University,University of North Carolina Chapel Hill,Corresponding author: Gunes Uzer PhD, Boise State University, Department of Mechanical & Biomedical Engineering, 1910 University Drive, MS-2085, Boise, ID 83725-2085, Ph. (208) 426-4461,
| | | | - Buer Sen
- University of North Carolina Chapel Hill
| | - Zhihui Xie
- University of North Carolina Chapel Hill
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Ercan U, Sen B, Brooks A, Joshi S. Escherichia coli
cellular responses to exposure to atmospheric‐pressure dielectric barrier discharge plasma‐treated N‐acetylcysteine solution. J Appl Microbiol 2018; 125:383-397. [DOI: 10.1111/jam.13777] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 03/15/2018] [Accepted: 03/27/2018] [Indexed: 12/30/2022]
Affiliation(s)
- U.K. Ercan
- College of Medicine Center for Surgical Infection and Biofilm Drexel University Philadelphia PA USA
| | - B. Sen
- College of Medicine Center for Surgical Infection and Biofilm Drexel University Philadelphia PA USA
| | - A.D. Brooks
- College of Medicine Center for Surgical Infection and Biofilm Drexel University Philadelphia PA USA
| | - S.G. Joshi
- College of Medicine Center for Surgical Infection and Biofilm Drexel University Philadelphia PA USA
- School of Biomedical Engineering, Science and Health Systems Drexel University Philadelphia PA USA
- A.J. Drexel Plasma Institute, Drexel University Philadelphia PA USA
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Paul GK, Sen B, Khan MK, Bhowmik TK, Khan TA, Roy AK. Pattern of Disease among Patients Attending Cardiology Outpatient Department of a Private Hospital of Mymensingh, Bangladesh. Mymensingh Med J 2018; 27:270-274. [PMID: 29769489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Epidemiologic transition is taking place in every part of the world. Cardiovascular diseases became the most common cause of death accounting for 30% of deaths worldwide, with 80% of the burden now occurring in developing countries. The objective of the study was to assess the Pattern of disease among patients attending Cardiology outpatient department of a private hospital. The cross sectional descriptive type of observational study was conducted among 550 patients attending Cardiology outpatient department (COPD) of Sodesh Hospital, Mymensingh, Bangladesh from March 2016 to June 2016. All the new patients attending COPD of Sodesh Hospital were selected purposively for the study. Data were collected by interview, physical examination and laboratory investigations of patients using a case record form. Mean age of the patients was 45.1 years with a SD of 15.6 years. Among the patients male were 291(52.9%), a bit higher than the female 259(47.1%). It was observed that more than half of the patients (281, 51.1%) visited cardiologist with non-cardiac problems. Less than one third of the patients (169, 30.7%) attended with cardiac problems and 100(18.2%) patients visited with both cardiac and non-cardiac problems. Among the cardiac diseases and symptoms hypertension was on the top of the list 176(65.4%). Ischemic heart diseases was present in 35(13.0%) and palpitation was in 30(11.1%) patients. On the other hand among the non-cardiac diseases or presentations, 121(43.1%) patients had non-specific chest pain, 63(22.4%) had shortness of breath and 17(6.1%) had diabetes mellitus. Hypertension was found the most frequent cardiovascular disease (65.4%) followed by ischemic heart disease (13.0%). More than half (51.1%) of the patients visit cardiologist with non-cardiac problems. Screening at the level of general practitioner (GP) and appropriate referral system can reduce extreme burden of patients to the cardiologists in the Cardiology outpatient department.
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Affiliation(s)
- G K Paul
- Dr Gobinda Kanti Paul, Consultant & Residential Physician, Department of Cardiology, Mymensingh Medical College Hospital, Bangladesh; E-mail:
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Thompson WR, Yen SS, Uzer G, Xie Z, Sen B, Styner M, Burridge K, Rubin J. LARG GEF and ARHGAP18 orchestrate RhoA activity to control mesenchymal stem cell lineage. Bone 2018; 107:172-180. [PMID: 29208526 PMCID: PMC5743610 DOI: 10.1016/j.bone.2017.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/29/2017] [Accepted: 12/01/2017] [Indexed: 02/02/2023]
Abstract
The quantity and quality of bone depends on osteoblastic differentiation of mesenchymal stem cells (MSCs), where adipogenic commitment depletes the available pool for osteogenesis. Cell architecture influences lineage decisions, where interfering with cytoskeletal structure promotes adipogenesis. Mechanical strain suppresses MSC adipogenesis partially through RhoA driven enhancement of cytoskeletal structure. To understand the basis of force-driven RhoA activation, we considered critical GEFs (activators) and GAPs (inactivators) on bone marrow MSC lineage fate. Knockdown of LARG accelerated adipogenesis and repressed basal RhoA activity. Importantly, mechanical activation of RhoA was almost entirely inhibited following LARG depletion, and the ability of strain to inhibit adipogenesis was impaired. Knockdown of ARHGAP18 increased basal RhoA activity and actin stress fiber formation, but did not enhance mechanical strain activation of RhoA. ARHGAP18 null MSCs exhibited suppressed adipogenesis assessed by Oil-Red-O staining and Western blot of adipogenic markers. Furthermore, ARHGAP18 knockdown enhanced osteogenic commitment, confirmed by alkaline phosphatase staining and qPCR of Sp7, Alpl, and Bglap genes. This suggests that ARHGAP18 conveys tonic inhibition of MSC cytoskeletal assembly, returning RhoA to an "off state" and affecting cell lineage in the static state. In contrast, LARG is recruited during dynamic mechanical strain, and is necessary for mechanical suppression of adipogenesis. In summary, mechanical activation of RhoA in mesenchymal progenitors is dependent on LARG, while ARHGAP18 limits RhoA delineated cytoskeletal structure in static cultures. Thus, on and off GTP exchangers work through RhoA to influence MSC fate and responses to static and dynamic physical factors in the microenvironment.
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Affiliation(s)
- William R Thompson
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, United States.
| | - Sherwin S Yen
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States; Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID 83725, United States.
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Keith Burridge
- Department of Cell Biology and Physiology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, United States.
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, United States.
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Samsonraj RM, Dudakovic A, Manzar B, Sen B, Dietz AB, Cool SM, Rubin J, van Wijnen AJ. Osteogenic Stimulation of Human Adipose-Derived Mesenchymal Stem Cells Using a Fungal Metabolite That Suppresses the Polycomb Group Protein EZH2. Stem Cells Transl Med 2017; 7:197-209. [PMID: 29280310 PMCID: PMC5788881 DOI: 10.1002/sctm.17-0086] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [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: 04/05/2017] [Accepted: 10/25/2017] [Indexed: 12/19/2022] Open
Abstract
Strategies for musculoskeletal tissue regeneration apply adult mesenchymal stem/stromal cells (MSCs) that can be sourced from bone marrow- and lipo-aspirates. Adipose tissue-derived MSCs are more easily harvested in the large quantities required for skeletal tissue-engineering approaches, but are generally considered to be less osteogenic than bone marrow MSCs. Therefore, we tested a new molecular strategy to improve their osteogenic lineage-differentiation potential using the fungal metabolite cytochalasin D (CytoD). We show that CytoD, which may function by redistributing the intracellular location of β-actin (ACTB), is a potent osteogenic stimulant as reflected by significant increases in alkaline phosphatase activity, extracellular matrix mineralization, and osteoblast-related gene expression (e.g., RUNX2, ALPL, SPARC, and TGFB3). RNA sequencing analyses of MSCs revealed that acute CytoD treatment (24 hours) stimulates a broad program of osteogenic biomarkers and epigenetic regulators. CytoD decreases mRNA and protein levels of the Polycomb chromatin regulator Enhancer of Zeste Homolog 2 (EZH2), which controls heterochromatin formation by mediating trimethylation of histone 3 lysine 27 (H3K27me3). Reduced EZH2 expression decreases cellular H3K27me3 marks indicating a global reduction in heterochromatin. We conclude that CytoD is an effective osteogenic stimulant that mechanistically functions by blocking both cytoplasmic actin polymerization and gene-suppressive epigenetic mechanisms required for the acquisition of the osteogenic phenotype in adipose tissue-derived MSCs. This finding supports the use of CytoD in advancing the osteogenic potential of MSCs in skeletal regenerative strategies. Stem Cells Translational Medicine 2018;7:197-209.
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Affiliation(s)
| | - Amel Dudakovic
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Bushra Manzar
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Allan B Dietz
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Simon M Cool
- Glycotherapeutics Group, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Andre J van Wijnen
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
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Styner M, Pagnotti GM, McGrath C, Wu X, Sen B, Uzer G, Xie Z, Zong X, Styner MA, Rubin CT, Rubin J. Exercise Decreases Marrow Adipose Tissue Through ß-Oxidation in Obese Running Mice. J Bone Miner Res 2017; 32:1692-1702. [PMID: 28436105 PMCID: PMC5550355 DOI: 10.1002/jbmr.3159] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 03/17/2017] [Accepted: 04/20/2017] [Indexed: 12/23/2022]
Abstract
The relationship between marrow adipose tissue (MAT) and bone health is poorly understood. We used running exercise to ask whether obesity-associated MAT can be attenuated via exercise and whether this correlates with gains in bone quantity and quality. C57BL/6 mice were divided into diet-induced obesity (DIO, n = 14) versus low-fat diet (LFD, n = 14). After 3 months, 16-week-old mice were allocated to an exercise intervention (LFD-E, DIO-E) or a control group (LFD, DIO) for 6 weeks (4 groups, n = 7/group). Marrow adipocyte area was 44% higher with obesity (p < 0.0001) and after exercise 33% lower in LFD (p < 0.0001) and 39% lower in DIO (p < 0.0001). In LFD, exercise did not affect adipocyte number; however, in DIO, the adipocyte number was 56% lower (p < 0.0001). MAT was 44% higher in DIO measured by osmium-μCT, whereas exercise associated with reduced MAT (-23% in LFD, -48% in DIO, p < 0.05). MAT was additionally quantified by 9.4TMRI, and correlated with osmium-µCT (r = 0.645; p < 0.01). Consistent with higher lipid beta oxidation, perilipin 3 (PLIN3) rose with exercise in tibial mRNA (+92% in LFD, +60% in DIO, p < 0.05). Tibial µCT-derived trabecular bone volume (BV/TV) was not influenced by DIO but responded to exercise with an increase of 19% (p < 0.001). DIO was associated with higher cortical periosteal and endosteal volumes of 15% (p = 0.012) and 35% (p < 0.01), respectively, but Ct.Ar/Tt.Ar was lower by 2.4% (p < 0.05). There was a trend for higher stiffness (N/m) in DIO, and exercise augmented this further. In conclusion, obesity associated with increases in marrow lipid-measured by osmium-μCT and MRI-and partially due to an increase in adipocyte size, suggesting increased lipid uptake into preexisting adipocytes. Exercise associated with smaller adipocytes and less bone lipid, likely invoking increased ß-oxidation and basal lipolysis as evidenced by higher levels of PLIN3. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Maya Styner
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
| | - Gabriel M Pagnotti
- Department of Biomedical Engineering, State University of New York, Stony Brook, Stony Brook, NY, USA
| | - Cody McGrath
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
| | - Xin Wu
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
| | - Buer Sen
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
| | - Gunes Uzer
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Zhihui Xie
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
| | - Xiaopeng Zong
- Department of Radiology and Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, NC, USA
| | - Martin A Styner
- Department of Computer Science, University of North Carolina, Chapel Hill, NC, USA
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Clinton T Rubin
- Department of Biomedical Engineering, State University of New York, Stony Brook, Stony Brook, NY, USA
| | - Janet Rubin
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC, USA
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Goldfarb SS, Locher JL, Preskitt J, Becker D, Davies SL, Sen B. Associations between participation in family activities and adolescent school problems. Child Care Health Dev 2017; 43:361-368. [PMID: 28101953 DOI: 10.1111/cch.12434] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 11/13/2016] [Accepted: 11/17/2016] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Adolescent risk outcomes related to school issues are widespread, with about 20% parents reporting poor school engagement amongst their youth. Previous literature suggests that adolescents who report strong bonds with their parents are often identified as being less likely to engage in risky behaviours, such as substance use. The current study sought to examine the association between the frequencies of selected family activities and school problems amongst adolescents after adjustments for family connectedness and other characteristics. METHODS Data were drawn from the National Longitudinal Survey of Youth, 1997. Of the 8984 youth interviewed, 3855 also had a sibling interviewed who met the selection criteria. School problem outcomes measured were suspension occurrence, poor grades and highest grade completed low for age. Independent variables of interest were self-reported frequency of family dinner, fun and religious activities in a typical week. Multivariable logistic models were estimated for each outcome, and multivariable linear probability models were estimated adjusting for family fixed effects. RESULTS Adjusting for family connectedness, there were significant associations between certain family activities and adolescent school problem measures. However, these results did not remain significant in models with family fixed effects, suggesting that associations could be driven by family-level confounders. DISCUSSION This study did not find strong evidence of a protective relationship between family activities and school problems. Therefore, it suggested that programme and policymakers be cautious in overstating the importance of family activities in preventing adolescent risk outcomes until true causal relationships can be determined.
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Affiliation(s)
- S S Goldfarb
- College of Medicine, Department of Behavioral Sciences and Social Medicine, Florida State University, Tallahassee, FL, USA
| | - J L Locher
- School of Public Health, Department of Health Care Organization and Policy, University of Alabama at Birmingham, Birmingham, AL, USA
| | - J Preskitt
- School of Public Health, Department of Health Care Organization and Policy, University of Alabama at Birmingham, Birmingham, AL, USA
| | - D Becker
- School of Public Health, Department of Health Care Organization and Policy, University of Alabama at Birmingham, Birmingham, AL, USA
| | - S L Davies
- School of Public Health, Department of Health Care Organization and Policy, University of Alabama at Birmingham, Birmingham, AL, USA
| | - B Sen
- School of Public Health, Department of Health Care Organization and Policy, University of Alabama at Birmingham, Birmingham, AL, USA
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Sen B, Uzer G, Samsonraj RM, Xie Z, McGrath C, Styner M, Dudakovic A, van Wijnen AJ, Rubin J. Intranuclear Actin Structure Modulates Mesenchymal Stem Cell Differentiation. Stem Cells 2017; 35:1624-1635. [PMID: 28371128 DOI: 10.1002/stem.2617] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [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: 12/05/2016] [Revised: 02/19/2017] [Accepted: 03/10/2017] [Indexed: 01/05/2023]
Abstract
Actin structure contributes to physiologic events within the nucleus to control mesenchymal stromal cell (MSC) differentiation. Continuous cytochalasin D (Cyto D) disruption of the MSC actin cytoskeleton leads to osteogenic or adipogenic differentiation, both requiring mass transfer of actin into the nucleus. Cyto D remains extranuclear, thus intranuclear actin polymerization is potentiated by actin transfer: we asked whether actin structure affects differentiation. We show that secondary actin filament branching via the Arp2/3 complex is required for osteogenesis and that preventing actin branching stimulates adipogenesis, as shown by expression profiling of osteogenic and adipogenic biomarkers and unbiased RNA-seq analysis. Mechanistically, Cyto D activates osteoblast master regulators (e.g., Runx2, Sp7, Dlx5) and novel coregulated genes (e.g., Atoh8, Nr4a3, Slfn5). Formin-induced primary actin filament formation is critical for Arp2/3 complex recruitment: osteogenesis is prevented by silencing of the formin mDia1, but not its paralog mDia2. Furthermore, while inhibition of actin, branching is a potent adipogenic stimulus, silencing of either mDia1 or mDia2 blocks adipogenic gene expression. We propose that mDia1, which localizes in the cytoplasm of multipotential MSCs and traffics into the nucleus after cytoskeletal disruption, joins intranuclear mDia2 to facilitate primary filament formation before mediating subsequent branching via Arp2/3 complex recruitment. The resulting intranuclear branched actin network specifies osteogenic differentiation, while actin polymerization in the absence of Arp2/3 complex-mediated secondary branching causes adipogenic differentiation. Stem Cells 2017;35:1624-1635.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.,Department of Mechanical/Biomedical Engineering, Boise State University, Boise, Idaho, USA
| | - Rebekah M Samsonraj
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Cody McGrath
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Amel Dudakovic
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Andre J van Wijnen
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.,Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, USA
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Affiliation(s)
- J Taneja
- Department of Microbiology, Dr. Dangs Laboratory Pvt. Ltd, New Delhi, India
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Meyer MB, Benkusky NA, Sen B, Rubin J, Pike JW. Epigenetic Plasticity Drives Adipogenic and Osteogenic Differentiation of Marrow-derived Mesenchymal Stem Cells. J Biol Chem 2016; 291:17829-47. [PMID: 27402842 DOI: 10.1074/jbc.m116.736538] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [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: 05/04/2016] [Indexed: 12/11/2022] Open
Abstract
Terminal differentiation of multipotent stem cells is achieved through a coordinated cascade of activated transcription factors and epigenetic modifications that drive gene transcription responsible for unique cell fate. Within the mesenchymal lineage, factors such as RUNX2 and PPARγ are indispensable for osteogenesis and adipogenesis, respectively. We therefore investigated genomic binding of transcription factors and accompanying epigenetic modifications that occur during osteogenic and adipogenic differentiation of mouse bone marrow-derived mesenchymal stem cells (MSCs). As assessed by ChIP-sequencing and RNA-sequencing analyses, we found that genes vital for osteogenic identity were linked to RUNX2, C/EBPβ, retinoid X receptor, and vitamin D receptor binding sites, whereas adipocyte differentiation favored PPARγ, retinoid X receptor, C/EBPα, and C/EBPβ binding sites. Epigenetic marks were clear predictors of active differentiation loci as well as enhancer activities and selective gene expression. These marrow-derived MSCs displayed an epigenetic pattern that suggested a default preference for the osteogenic pathway; however, these patterns were rapidly altered near the Adipoq, Cidec, Fabp4, Lipe, Plin1, Pparg, and Cebpa genes during adipogenic differentiation. Surprisingly, we found that these cells also exhibited an epigenetic plasticity that enabled them to trans-differentiate from adipocytes to osteoblasts (and vice versa) after commitment, as assessed by staining, gene expression, and ChIP-quantitative PCR analysis. The osteogenic default pathway may be subverted during pathological conditions, leading to skeletal fragility and increased marrow adiposity during aging, estrogen deficiency, and skeletal unloading. Taken together, our data provide an increased mechanistic understanding of the epigenetic programs necessary for multipotent differentiation of MSCs that may prove beneficial in the development of therapeutic strategies.
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Affiliation(s)
- Mark B Meyer
- From the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706 and
| | - Nancy A Benkusky
- From the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706 and
| | - Buer Sen
- the Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27514
| | - Janet Rubin
- the Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27514
| | - J Wesley Pike
- From the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706 and
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Sen B, Xie Z, Uzer G, Thompson WR, Styner M, Wu X, Rubin J. Intranuclear Actin Regulates Osteogenesis. Stem Cells 2016; 33:3065-76. [PMID: 26140478 DOI: 10.1002/stem.2090] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 06/02/2015] [Accepted: 06/06/2015] [Indexed: 12/22/2022]
Abstract
Depolymerization of the actin cytoskeleton induces nuclear trafficking of regulatory proteins and global effects on gene transcription. We here show that in mesenchymal stem cells (MSCs), cytochalasin D treatment causes rapid cofilin-/importin-9-dependent transfer of G-actin into the nucleus. The continued presence of intranuclear actin, which forms rod-like structures that stain with phalloidin, is associated with induction of robust expression of the osteogenic genes osterix and osteocalcin in a Runx2-dependent manner, and leads to acquisition of osteogenic phenotype. Adipogenic differentiation also occurs, but to a lesser degree. Intranuclear actin leads to nuclear export of Yes-associated protein (YAP); maintenance of nuclear YAP inhibits Runx2 initiation of osteogenesis. Injection of cytochalasin into the tibial marrow space of live mice results in abundant bone formation within the space of 1 week. In sum, increased intranuclear actin forces MSC into osteogenic lineage through controlling Runx2 activity; this process may be useful for clinical objectives of forming bone.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - William R Thompson
- Department of Physical Therapy, University of Indiana-Purdue, Indianapolis, Indiana
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Xin Wu
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
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Kaynak-Onurdag F, Okten S, Sen B. Screening Brucella spp. in bovine raw milk by real-time quantitative PCR and conventional methods in a pilot region of vaccination, Edirne, Turkey. J Dairy Sci 2016; 99:3351-3357. [DOI: 10.3168/jds.2015-10637] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 12/10/2015] [Indexed: 12/11/2022]
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Uzer G, Thompson WR, Sen B, Xie Z, Yen SS, Miller S, Bas G, Styner M, Rubin CT, Judex S, Burridge K, Rubin J. Cell Mechanosensitivity to Extremely Low-Magnitude Signals Is Enabled by a LINCed Nucleus. Stem Cells 2016; 33:2063-76. [PMID: 25787126 DOI: 10.1002/stem.2004] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [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: 09/29/2014] [Revised: 01/19/2015] [Accepted: 02/19/2015] [Indexed: 12/21/2022]
Abstract
A cell's ability to recognize and adapt to the physical environment is central to its survival and function, but how mechanical cues are perceived and transduced into intracellular signals remains unclear. In mesenchymal stem cells (MSCs), high-magnitude substrate strain (HMS, ≥2%) effectively suppresses adipogenesis via induction of focal adhesion (FA) kinase (FAK)/mTORC2/Akt signaling generated at FAs. Physiologic systems also rely on a persistent barrage of low-level signals to regulate behavior. Exposing MSC to extremely low-magnitude mechanical signals (LMS) suppresses adipocyte formation despite the virtual absence of substrate strain (<0.001%), suggesting that LMS-induced dynamic accelerations can generate force within the cell. Here, we show that MSC response to LMS is enabled through mechanical coupling between the cytoskeleton and the nucleus, in turn activating FAK and Akt signaling followed by FAK-dependent induction of RhoA. While LMS and HMS synergistically regulated FAK activity at the FAs, LMS-induced actin remodeling was concentrated at the perinuclear domain. Preventing nuclear-actin cytoskeleton mechanocoupling by disrupting linker of nucleoskeleton and cytoskeleton (LINC) complexes inhibited these LMS-induced signals as well as prevented LMS repression of adipogenic differentiation, highlighting that LINC connections are critical for sensing LMS. In contrast, FAK activation by HMS was unaffected by LINC decoupling, consistent with signal initiation at the FA mechanosome. These results indicate that the MSC responds to its dynamic physical environment not only with "outside-in" signaling initiated by substrate strain, but vibratory signals enacted through the LINC complex enable matrix independent "inside-inside" signaling.
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Affiliation(s)
- Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - William R Thompson
- School of Physical Therapy, Indiana University, Indianapolis, Indiana, USA
| | - Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Sherwin S Yen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Sean Miller
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Guniz Bas
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Clinton T Rubin
- Department of Biomedical Engineering, State University of New York, Stony Brook, New York, USA
| | - Stefan Judex
- Department of Biomedical Engineering, State University of New York, Stony Brook, New York, USA
| | - Keith Burridge
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
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Sen B, Joshi S. Studies on Acinetobacter baumannii
involving multiple mechanisms of carbapenem resistance. J Appl Microbiol 2016; 120:619-29. [DOI: 10.1111/jam.13037] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 12/15/2015] [Accepted: 12/17/2015] [Indexed: 01/26/2023]
Affiliation(s)
- B. Sen
- Department of Microbiology and Immunology; Center for Surgical Infections and Biofilms; Drexel University; Philadelphia 19102 PA USA
| | - S.G. Joshi
- Department of Microbiology and Immunology; Center for Surgical Infections and Biofilms; Drexel University; Philadelphia 19102 PA USA
- School of Biomedical Engineering, Science and Health Systems; Center for Surgical Infections and Biofilms; Drexel University; Philadelphia 19102 PA USA
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Morton TL, Galior K, McGrath C, Wu X, Uzer G, Uzer GB, Sen B, Xie Z, Tyson D, Rubin J, Styner M. Exercise Increases and Browns Muscle Lipid in High-Fat Diet-Fed Mice. Front Endocrinol (Lausanne) 2016; 7:80. [PMID: 27445983 PMCID: PMC4928595 DOI: 10.3389/fendo.2016.00080] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 06/20/2016] [Indexed: 12/25/2022] Open
Abstract
Muscle lipid increases with high-fat feeding and diabetes. In trained athletes, increased muscle lipid is not associated with insulin resistance, a phenomenon known as the athlete's paradox. To understand if exercise altered the phenotype of muscle lipid, female C57BL/6 mice fed CTL or high-fat diet (HFD for 6 or 18 weeks) were further divided into sedentary or exercising groups (CTL-E or HFD-E) with voluntary access to running wheels for the last 6 weeks of experiments, running 6 h/night. Diet did not affect running time or distance. HFD mice weighed more than CTL after 18 weeks (p < 0.01). Quadriceps muscle TG was increased in running animals and in sedentary mice fed HFD for 18 weeks (p < 0.05). In exercised animals, markers of fat, Plin1, aP2, FSP27, and Fasn, were increased significantly in HFD groups. Ucp1 and Pgc1a, markers for brown fat, increased with exercise in the setting of high fat feeding. Fndc5, which encodes irisin, and CytC were sensitive to exercise regardless of diet. Plin5 was increased with HFD and unaffected by exercise; the respiratory exchange ratio was 15% lower in the 18-week HFD group compared with CTL (p < 0.001) and 10% lower in 18 weeks HFD-E compared with CTL-E (p < 0.001). Increased Ucp1 and Pgc1a in exercised muscle of running mice suggests that a beige/brown fat phenotype develops, which differs from the fat phenotype that induces insulin resistance in high fat feeding. This suggests that increased muscle lipid may develop a "brown" phenotype in the setting of endurance exercise training, a shift that is further promoted by HFD.
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Affiliation(s)
- Tiffany L. Morton
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kornelia Galior
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Cody McGrath
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Xin Wu
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gunes Uzer
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Guniz Bas Uzer
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Buer Sen
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Zhihui Xie
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - David Tyson
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Janet Rubin
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Maya Styner
- Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- *Correspondence: Maya Styner,
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Styner M, Pagnotti GM, Galior K, Wu X, Thompson WR, Uzer G, Sen B, Xie Z, Horowitz MC, Styner MA, Rubin C, Rubin J. Exercise Regulation of Marrow Fat in the Setting of PPARγ Agonist Treatment in Female C57BL/6 Mice. Endocrinology 2015; 156:2753-61. [PMID: 26052898 PMCID: PMC4511140 DOI: 10.1210/en.2015-1213] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The contribution of marrow adipose tissue (MAT) to skeletal fragility is poorly understood. Peroxisome proliferator-activated receptor (PPAR)γ agonists, associated with increased fractures in diabetic patients, increase MAT. Here, we asked whether exercise could limit the MAT accrual and increase bone formation in the setting of PPARγ agonist treatment. Eight-week-old female C57BL/6 mice were treated with 20-mg/kg · d rosiglitazone (Rosi) and compared with control (CTL) animals. Exercise groups ran 12 km/d when provided access to running wheels (CTL exercise [CTL-E], Rosi-E). After 6 weeks, femoral MAT (volume of lipid binder osmium) and tibial bone morphology were assessed by microcomputer tomography. Rosi was associated with 40% higher femur MAT volume compared with CTL (P < .0001). Exercise suppressed MAT volume by half in CTL-E mice compared with CTL (P < .01) and 19% in Rosi-E compared with Rosi (P < .0001). Rosi treatment increased fat markers perilipin and fatty acid synthase mRNA by 4-fold (P < .01). Exercise was associated with increased uncoupling protein 1 mRNA expression in both CTL-E and Rosi-E groups (P < .05), suggestive of increased brown fat. Rosi increased cortical porosity (P < .0001) but did not significantly impact trabecular or cortical bone quantity. Importantly, exercise induction of trabecular bone volume was not prevented by Rosi (CTL-E 21% > CTL, P < .05; Rosi-E 26% > Rosi, P < .01). In summary, despite the Rosi induction of MAT extending well into the femoral diaphysis, exercise was able to significantly suppress MAT volume and induce bone formation. Our results suggest that the impact of PPARγ agonists on bone and marrow health can be partially mitigated by exercise.
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Affiliation(s)
- Maya Styner
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Gabriel M Pagnotti
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Kornelia Galior
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Xin Wu
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - William R Thompson
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Gunes Uzer
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Buer Sen
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Zhihui Xie
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Mark C Horowitz
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Martin A Styner
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Clinton Rubin
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
| | - Janet Rubin
- Department of Medicine (M.S., K.G., X.W., G.U., B.S., Z.X., J.R.), University of North Carolina, Chapel Hill, North Carolina; Department of Physical Therapy (W.R.T.), Indiana University, Indianapolis, Indiana; Department of Computer Science (M.A.S.), University of North Carolina, Chapel Hill, North Carolina; Department of Psychiatry (M.A.S.), Image Analysis, University of North Carolina, Chapel Hill, North Carolina; Department of Biomedical Engineering (G.M.P., C.R.), Stony Brook University, Stony Brook, New York; and Department of Orthopedics and Rehabilitation (M.C.H.), Yale University, New Haven, Connecticut
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Sasmal PK, Das PC, Tantia O, Patle N, Khanna S, Sen B. Acute small intestinal obstruction-an unusual complication of capsule endoscopy. Indian J Surg 2015; 77:21-3. [PMID: 25972632 DOI: 10.1007/s12262-014-1051-4] [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: 01/30/2010] [Accepted: 03/29/2010] [Indexed: 10/25/2022] Open
Abstract
We report a case of endoscopic capsule impaction causing acute small intestinal obstruction in a patient with Crohn's disease (CD), having obscure gastrointestinal bleeding. A 57-year old female presented with features of acute small bowel obstruction 2 days after capsule endoscopy elsewhere for the evaluation of intermittent bleeding per rectum and iron deficiency anemia. Patient underwent an exploratory laparotomy with right hemicolectomy for the diseased ileocecal region which mimicked malignancy. The capsule was found to be impacted in the strictured lumen of the terminal ileum. Post operative histopathological examination revealed it to be Crohn's disease.
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Affiliation(s)
- Prakash K Sasmal
- Department of Minimal Access Surgery, ILS Hospital, DD-6, Sector 1, Salt Lake City, Kolkata, West Bengal 700064 India
| | - Prakhar C Das
- Department of Minimal Access Surgery, ILS Hospital, DD-6, Sector 1, Salt Lake City, Kolkata, West Bengal 700064 India
| | - Om Tantia
- Department of Minimal Access Surgery, ILS Hospital, DD-6, Sector 1, Salt Lake City, Kolkata, West Bengal 700064 India
| | - Nirmal Patle
- Department of Minimal Access Surgery, ILS Hospital, DD-6, Sector 1, Salt Lake City, Kolkata, West Bengal 700064 India
| | - S Khanna
- Department of Minimal Access Surgery, ILS Hospital, DD-6, Sector 1, Salt Lake City, Kolkata, West Bengal 700064 India
| | - B Sen
- Department of Minimal Access Surgery, ILS Hospital, DD-6, Sector 1, Salt Lake City, Kolkata, West Bengal 700064 India
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Paul GK, Sen B, Rahman MZ, Ali M, Rahman MM, Rokonuzzaman SM. Correlation of platelet count and acute ST-elevation myocardial infarction. Mymensingh Med J 2014; 23:637-643. [PMID: 25481578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The study was conducted in the Department of cardiology, NICVD Dhaka during the period January 2006 to December 2007 to assess the impact of platelet on ST-elevation myocardial infarction (STEMI). To perform this prospective study 200 patients with STEMI within 72 hours of chest pain of both sexes were randomly selected and were evaluated by clinical history, physical examination and with the help of ECG, Echocardiography and others cardiac risk factors analysis. Heparin therapy before admission, previously documented thrombocytopenia (<140,000/cmm), history of previous or current haemostatic disorder, renal impairment (Creatinine >1.6mg/dl) and history of PCI & CABG were excluded in this study. Patient of Platelet count (PC) ≤200000/cubic millimeter (cmm) in Group I and patient of Group II, platelet counts were PC >200000/cmm. Follow up period was 3 days to 7 days after hospital admission. Primary outcome heart failure (any Killip class) was significantly more in Group II than Group I (40.0% vs. 23.0%; p=0.009). Though the incidence of Killip class I and cardiogenic shock were not significant between these two groups but Killip class II (18.0% vs. 8.0%; p=0.036) and Killip class III (15.0% vs. 6.0%; p=0.037) heart failure were significantly more among the patient with higher platelet counts. In-hospital mortality, one of the primary outcomes of this study, was significantly higher in Group II (13.0%) than Group I (5.0 %) and p value was 0.048. Re-infarction was more in patient with higher platelet counts group (Group II) than patients with lower platelet count (Group I) but statistically was not significant (16.0% vs.11.0%; p=0.300).
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Affiliation(s)
- G K Paul
- Dr Gobinda Kanti Paul, Assistant Professor, Department of Cardiology, Mymensingh Medical College (MMC), Mymensingh, Bangladesh
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Thompson WR, Guilluy C, Xie Z, Sen B, Brobst KE, Yen SS, Uzer G, Styner M, Case N, Burridge K, Rubin J. Mechanically activated Fyn utilizes mTORC2 to regulate RhoA and adipogenesis in mesenchymal stem cells. Stem Cells 2014; 31:2528-37. [PMID: 23836527 DOI: 10.1002/stem.1476] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [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: 04/25/2013] [Revised: 06/05/2013] [Accepted: 06/18/2013] [Indexed: 01/17/2023]
Abstract
Mechanical strain provides an anti-adipogenic, pro-osteogenic stimulus to mesenchymal stem cells (MSC) through generating intracellular signals and via cytoskeletal restructuring. Recently, mTORC2 has been shown to be a novel mechanical target critical for the anti-adipogenic signal leading to preservation of β-catenin. As mechanical activation of mTORC2 requires focal adhesions (FAs), we asked whether proximal signaling involved Src and FAK, which are early responders to integrin-FA engagement. Application of mechanical strain to marrow-derived MSCs was unable to activate mTORC2 when Src family kinases were inhibited. Fyn, but not Src, was specifically required for mechanical activation of mTORC2 and was recruited to FAs after strain. Activation of mTORC2 was further diminished following FAK inhibition, and as FAK phosphorylation (Tyr-397) required Fyn activity, provided evidence of Fyn/FAK cooperativity. Inhibition of Fyn also prevented mechanical activation of RhoA as well as mechanically induced actin stress fiber formation. We thus asked whether RhoA activation by strain was dependent on mTORC2 downstream of Fyn. Inhibition of mTORC2 or its downstream substrate, Akt, both prevented mechanical RhoA activation, indicating that Fyn/FAK affects cytoskeletal structure via mTORC2. We then sought to ascertain whether this Fyn-initiated signal pathway modulated MSC lineage decisions. siRNA knockdown of Fyn, but not Src, led to rapid attainment of adipogenic phenotype with significant increases in adipocyte protein 2, peroxisome proliferator-activated receptor gamma, adiponectin, and perilipin. As such, Fyn expression in mdMSCs contributes to basal cytoskeletal architecture and, when associated with FAs, functions as a proximal mechanical effector for environmental signals that influence MSC lineage allocation.
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Affiliation(s)
- William R Thompson
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
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Shen Y, Yaqin Z, Xin W, Sen B, Xiaoqin J, Qinfeng X, Feng X. High-Dose Hypofractionated Stereotactic Body Radiation Therapy (SBRT) for Isolated Lung Metastasis From Colorectal Cancer: Preliminary Results. Int J Radiat Oncol Biol Phys 2014. [DOI: 10.1016/j.ijrobp.2014.05.1258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Styner M, Thompson WR, Galior K, Uzer G, Wu X, Kadari S, Case N, Xie Z, Sen B, Romaine A, Pagnotti GM, Rubin CT, Styner MA, Horowitz MC, Rubin J. Bone marrow fat accumulation accelerated by high fat diet is suppressed by exercise. Bone 2014; 64:39-46. [PMID: 24709686 PMCID: PMC4041820 DOI: 10.1016/j.bone.2014.03.044] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 02/17/2014] [Accepted: 03/25/2014] [Indexed: 01/14/2023]
Abstract
Marrow adipose tissue (MAT), associated with skeletal fragility and hematologic insufficiency, remains poorly understood and difficult to quantify. We tested the response of MAT to high fat diet (HFD) and exercise using a novel volumetric analysis, and compared it to measures of bone quantity. We hypothesized that HFD would increase MAT and diminish bone quantity, while exercise would slow MAT acquisition and promote bone formation. Eight week-old female C57BL/6 mice were fed a regular (RD) or HFD, and exercise groups were provided voluntary access to running wheels (RD-E, HFD-E). Femoral MAT was assessed by μCT (lipid binder osmium) using a semi-automated approach employing rigid co-alignment, regional bone masks and was normalized for total femoral volume (TV) of the bone compartment. MAT was 2.6-fold higher in HFD relative to RD mice. Exercise suppressed MAT in RD-E mice by more than half compared with RD. Running similarly inhibited MAT acquisition in HFD mice. Exercise significantly increased bone quantity in both diet groups. Thus, HFD caused significant accumulation of MAT; importantly running exercise limited MAT acquisition while promoting bone formation during both diets. That MAT is exquisitely responsive to diet and exercise, and its regulation by exercise appears to be inversely proportional to effects on exercise induced bone formation, is relevant for an aging and sedentary population.
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Affiliation(s)
- Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA.
| | - William R Thompson
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Kornelia Galior
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Xin Wu
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Sanjay Kadari
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Natasha Case
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Andrew Romaine
- Department of Psychiatry and Computer Science, University of North Carolina, Chapel Hill, NC, USA
| | - Gabriel M Pagnotti
- Department of Biomedical Engineering, State University of New York, Stony Brook, NY, USA
| | - Clinton T Rubin
- Department of Biomedical Engineering, State University of New York, Stony Brook, NY, USA
| | - Martin A Styner
- Department of Computer Science, University of North Carolina, Chapel Hill, NC, USA; Department of Psychiatry and Computer Science, University of North Carolina, Chapel Hill, NC, USA
| | - Mark C Horowitz
- Department of Orthopedics and Rehabilitation, Yale University, New Haven, CT, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
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Chakraborty R, Sen B, Chattopadhyay P. Zirconium-titanium-phosphate nanoparticles: Triton X-100 based size
modification, characterization and application in radiochemical separation. RADIOCHIM ACTA 2014. [DOI: 10.1515/ract-2014-2115] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Zirconium-titanium-phosphate nanoparticles (ZTP) of different sizes were synthesized using tritron X-100 (polyethylene
glycol-p-isooctylphenyl ether) surfactant. The materials were characterized by FTIR and powdered X-ray diffraction (XRD). The
structural and morphological details of the material were obtained by scanning electron microscopy (SEM) and transmission
electron microscopy (TEM). The SEM study was followed by energy dispersive spectroscopic analysis (EDS) for elemental analysis
of the sample. The important peaks of the XRD spectra were analyzed to determine the probable composition of the material. The
particle sizes were determined by dynamic light scattering (DLS) method. Ion exchange capacity was measured for different metal
ions with sizes of the ZTP nanoparticles and size-dependent ion exchange property of the material was investigated
thoroughly. The nanomaterial of the smallest size of around 5 nm was employed to separate carrier-free
137mBa from 137Cs in column chromatographic technique using 1.0 M HNO3 as
eluting agent at pH = 5.
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Affiliation(s)
- R. Chakraborty
- Department of Chemistry, The University Burdwan, Golapbag, Burdwan-713104, India
| | - B. Sen
- Department of Chemistry, The University Burdwan, Golapbag, Burdwan-713104, India
| | - P. Chattopadhyay
- Department of Chemistry, The University Burdwan, Golapbag, Burdwan-713104, India
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Sen B, Xie Z, Case N, Thompson WR, Uzer G, Styner M, Rubin J. mTORC2 regulates mechanically induced cytoskeletal reorganization and lineage selection in marrow-derived mesenchymal stem cells. J Bone Miner Res 2014; 29:78-89. [PMID: 23821483 PMCID: PMC3870029 DOI: 10.1002/jbmr.2031] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 06/13/2013] [Accepted: 06/18/2013] [Indexed: 01/29/2023]
Abstract
The cell cytoskeleton interprets and responds to physical cues from the microenvironment. Applying mechanical force to mesenchymal stem cells induces formation of a stiffer cytoskeleton, which biases against adipogenic differentiation and toward osteoblastogenesis. mTORC2, the mTOR complex defined by its binding partner rictor, is implicated in resting cytoskeletal architecture and is activated by mechanical force. We asked if mTORC2 played a role in mechanical adaptation of the cytoskeleton. We found that during bi-axial strain-induced cytoskeletal restructuring, mTORC2 and Akt colocalize with newly assembled focal adhesions (FA). Disrupting the function of mTORC2, or that of its downstream substrate Akt, prevented mechanically induced F-actin stress fiber development. mTORC2 becomes associated with vinculin during strain, and knockdown of vinculin prevents mTORC2 activation. In contrast, mTORC2 is not recruited to the FA complex during its activation by insulin, nor does insulin alter cytoskeletal structure. Further, when rictor was knocked down, the ability of mesenchymal stem cells (MSC) to enter the osteoblastic lineage was reduced, and when cultured in adipogenic medium, rictor-deficient MSC showed accelerated adipogenesis. This indicated that cytoskeletal remodeling promotes osteogenesis over adipogenesis. In sum, our data show that mTORC2 is involved in stem cell responses to biophysical stimuli, regulating both signaling and cytoskeletal reorganization. As such, mechanical activation of mTORC2 signaling participates in mesenchymal stem cell lineage selection, preventing adipogenesis by preserving β-catenin and stimulating osteogenesis by generating a stiffer cytoskeleton.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
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Gungor ANC, Kalkan G, Oguz S, Sen B, Ozoguz P, Takci Z, Sacar H, Dogan FB, Cicek D. Behcet disease and pregnancy. CLIN EXP OBSTET GYN 2014; 41:617-619. [PMID: 25551950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
PURPOSE Behcet disease (BD) is a multisystemic vaculitis commonly diagnosed in reproductive years. The authors aimed to investigate the relationship between BD and pregnancy outcomes. MATERIALS AND METHODS In this multicenter retrospective survey study, the authors compared the pregnancy outcomes of BD patients with the healthy controls. RESULTS A total of 298 pregnancies of 94 patients with BD and 219 pregnancies of 95 healthy controls were evaluated. The mean birth weight of all babies of women with BD and the control group were 3,214 grams and 3,351 grams, respectively (p = 0.028). The miscarriage rates were also higher in the BD group. The com- plication rates of pregnancy with hypertension, preeclampsia, preterm labour in the study group and the control group were 12.8% and 11.6%, respectively (p = 0.489). CONCLUSION The current study demonstrated that BD patients delivered smaller babies and they have higher miscarriage rates when compared to the healthy controls which might be due to the vasculitis of the placenta.
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Affiliation(s)
- A N C Gungor
- Canakkale 18 March University Hospital, Obstetrics and Gynecology Department, Turkey.
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Celik O, Koltka N, Devrim S, Sen B, Gura Celik M. Clinical pulmonary infection score calculator in the early diagnosis and treatment of ventilator-associated pneumonia in the ICU. Crit Care 2014. [PMCID: PMC4069557 DOI: 10.1186/cc13494] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Köroglu S, Sen B, Havan N, Suner A, Aksu E, Aydın N. PP-054 AN UNUSUAL CAUSE OF CHEST PAIN. Int J Cardiol 2013. [DOI: 10.1016/s0167-5273(13)70258-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Case N, Thomas J, Xie Z, Sen B, Styner M, Rowe D, Rubin J. Mechanical input restrains PPARγ2 expression and action to preserve mesenchymal stem cell multipotentiality. Bone 2013; 52:454-64. [PMID: 22951341 PMCID: PMC3535265 DOI: 10.1016/j.bone.2012.08.122] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/24/2012] [Accepted: 08/12/2012] [Indexed: 10/28/2022]
Abstract
Exercise-generated signals are pro-osteogenic and anti-adipogenic within the marrow. In vitro studies indicate that mechanical signals directly block adipogenic differentiation through activation of β-catenin and by limiting PPARγ2 expression. Whether mechanically generated β-catenin can inhibit adipogenesis during PPARγ transactivation is unknown. We evaluated the ability of mechanical signals to limit adipogenesis in marrow derived mesenchymal stem cells (mdMSC) distal to activation of PPARγ. First, we established that mdMSC attained an adipogenic phenotype within 2-4 days in the presence of rosiglitazone (1-25 μM) and that β-catenin activation via GSK3β inhibition interfered with this process. Similarly, mechanical strain (3600 cycles, 2% strain daily) inhibited adipogenesis at 3 days, preventing rosiglitazone-induced PPARγ upregulation as well as aP2 and adiponectin protein expression. To assess whether a reduction in PPARγ expression was necessary for anti-adipogenic action, PPARγ2 was overexpressed: both mechanical strain and GSK3β inhibition prevented expression of aP2 and adiponectin proteins despite abundant PPARγ2 and its ligand. To understand the fate of single cells experiencing mechanical strain we generated mdMSC from aP2-GFP reporter expressing mice. Rosiglitazone treatment for 3 days induced GFP expression in more than 80% of cells. Sorting by GFP expression revealed that the highest 20% of aP2-GFP expressing cells was responsible for the majority of adipogenic protein expression. This highly expressing GFP fraction had a reduced ability to respond to an osteogenic stimulus: BMP-2 treatment increased osterix by 12-fold in contrast to the 42-fold increase in osterix expression that resulted from BMP-2 treatment of the bottom 75% of GFP expressing cells. This suggested that highly expressing aP2-GFP cells represented more terminally differentiated adipocytes, with reduced multipotentiality. Application of mechanical strain to aP2-GFP mdMSC treated with rosiglitazone caused a two-fold decrease in the size of the upper cell fraction, suggesting that mechanical strain preserved MSC in a multipotent state. Our data show that mechanical strain restricts adipogenesis both by limiting PPARγ2 expression and by preventing PPARγ action, protecting the potential of MSC to enter other lineages.
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Affiliation(s)
- Natasha Case
- Department of Medicine, University of North Carolina, 125 MacNider Hall, CB# 7005, Chapel Hill, NC 27599 U.S.A
| | - Jacob Thomas
- Department of Medicine, University of North Carolina, 125 MacNider Hall, CB# 7005, Chapel Hill, NC 27599 U.S.A
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, 125 MacNider Hall, CB# 7005, Chapel Hill, NC 27599 U.S.A
| | - Buer Sen
- Department of Medicine, University of North Carolina, 125 MacNider Hall, CB# 7005, Chapel Hill, NC 27599 U.S.A
| | - Maya Styner
- Department of Medicine, University of North Carolina, 125 MacNider Hall, CB# 7005, Chapel Hill, NC 27599 U.S.A
| | - David Rowe
- Department of Reconstructive Sciences, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, Connecticut 06030 U.S.A
| | - Janet Rubin
- Department of Medicine, University of North Carolina, 125 MacNider Hall, CB# 7005, Chapel Hill, NC 27599 U.S.A
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Nightingale RW, Roche AE, Kumer JB, Mergenthaler JL, Gille JC, Massie ST, Bailey PL, Edwards DP, Gunson MR, Toon GC, Sen B, Blavier JF, Connell PS. Global CF2Cl2measurements by UARS cryogenic limb array etalon spectrometer: Validation by correlative data and a model. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/96jd00597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Styner M, Meyer MB, Galior K, Case N, Xie Z, Sen B, Thompson WR, Pike JW, Rubin J. Mechanical strain downregulates C/EBPβ in MSC and decreases endoplasmic reticulum stress. PLoS One 2012; 7:e51613. [PMID: 23251594 PMCID: PMC3520924 DOI: 10.1371/journal.pone.0051613] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 11/02/2012] [Indexed: 01/05/2023] Open
Abstract
Exercise prevents marrow mesenchymal stem cell (MSC) adipogenesis, reversing trends that accompany aging and osteoporosis. Mechanical input, the in-vitro analogue to exercise, limits PPARγ expression and adipogenesis in MSC. We considered whether C/EBPβ might be mechanoresponsive as it is upstream to PPARγ, and also is known to upregulate endoplasmic reticulum (ER) stress. MSC (C3H10T1/2 pluripotent cells as well as mouse marrow-derived MSC) were cultured in adipogenic media and a daily mechanical strain regimen was applied. We demonstrate herein that mechanical strain represses C/EBPβ mRNA (0.6-fold ±0.07, p<0.05) and protein (0.4-fold ±0.1, p<0.01) in MSC. SiRNA silencing of β-catenin prevented mechanical repression of C/EBPβ. C/EBPβ overexpression did not override strain's inhibition of adipogenesis, which suggests that mechanical control of C/EBPβ is not the primary site at which adipogenesis is regulated. Mechanical inhibition of C/EBPβ, however, might be critical for further processes that regulate MSC health. Indeed, overexpression of C/EBPβ in MSC induced ER stress evidenced by a dose-dependent increase in the pro-apoptotic CHOP (protein 4-fold ±0.5, p<0.05) and a threshold reduction in the chaperone BiP (protein 0.6-fold ±0.1, p = 0.2; mRNA 0.3-fold ±0.1, p<0.01). ChIP-seq demonstrated a significant association between C/EBPβ and both CHOP and BiP genes. The strain regimen, in addition to decreasing C/EBPβ mRNA (0.5-fold ±0.09, p<0.05), expanded ER capacity as measured by an increase in BiP mRNA (2-fold ±0.2, p<0.05) and protein. Finally, ER stress induced by tunicamycin was ameliorated by mechanical strain as demonstrated by decreased C/EBPβ, increased BiP and decreased CHOP protein expression. Thus, C/EBPβ is a mechanically responsive transcription factor and its repression should counter increases in marrow fat as well as improve skeletal resistance to ER stress.
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Affiliation(s)
- Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.
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Sen B, Niemann B, Roth P, Aser R, Schonburg M, Boning A. Short- and long-term outcomes in octogenarians after coronary artery bypass surgery. Eur J Cardiothorac Surg 2012; 42:e102-7. [DOI: 10.1093/ejcts/ezs410] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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Sen B, Paul GK, Rahman MM, Shahidullah SM. Thyroid hormone status in apparently healthy elderly persons. Mymensingh Med J 2012; 21:423-429. [PMID: 22828537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Thyroid disorders are frequent in elderly population and difficult to recognize because of their atypical presentation, and the absence of classic signs and symptoms. Nonspecific symptoms, even in the absence of thyroid dysfunction, are common in this age group, including fatigue, anorexia, weight loss, failure to rehabilitate, and difficult to concentrate. Symptoms of aging can be confused easily with hypothyroidism. The interpretation of thyroid function tests is also cumbersome in aged individuals because of the difficulty in differentiating physiologic age-associated changes from alterations secondary to acute or chronic non-thyroidal illness. In the present study, a total 100 subjects were included. Subjects were divided into two groups: Group I - Control (n=50) and Group II - Case (n=50). Fifty apparently healthy young adults were taken as control (Group I) and 50 apparently healthy elderly subjects were included in case (Group II). Group I was subdivided into two groups- Group IA: young male (n=25) and Group IB: young female (n=25). Group II was also subdivided into two groups - Group IIA: elderly male (n=25) and Group IIB: elderly female (n=25). All the subjects were selected from the local community of Mymensingh Sadar, Mymensingh Medical College, Mymensingh and Community Based Medical College, Bangladesh, Mymensingh. In the present study, the difference of mean serum T3 concentration between Group I (control) and Group II (elderly subjects) was not found to be significant (p>0.05). Significant difference in serum TSH concentration between Group IA and Group IIA was to be found (p<0.001). The difference of mean serum T4 concentration between Group IB and Group IIB was not found significant (p>0.05). Significant difference in mean serum TSH concentration between Group IB and Group IIB was to be found (p<0.001).
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Affiliation(s)
- B Sen
- Department of Biochemistry, Community Based Medical College, Bangladesh, Mymensingh, Bangladesh
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Sen B, Guilluy C, Xie Z, Case N, Styner M, Thomas J, Oguz I, Rubin C, Burridge K, Rubin J. Mechanically induced focal adhesion assembly amplifies anti-adipogenic pathways in mesenchymal stem cells. Stem Cells 2012; 29:1829-36. [PMID: 21898699 DOI: 10.1002/stem.732] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The fate of pluripotent mesenchymal stem cells (MSC) is determined through integration of chemical, spatial, and physical signals. The suppression of MSC adipogenesis by mechanical stimuli, which requires Akt-induced inhibition of glycogen synthase kinase 3β (GSK3β) with β-catenin activation, can be enhanced by repetitive dosing within a single day. Here, we demonstrate that reapplication of cyclic strain within a 24-hour period leads to amplification of both Akt activation and its subsequent inhibition of GSK3β, such that total cycle number can be reduced while still inhibiting adipogenesis. Amplification of Akt signaling is facilitated by a dynamic restructuring of the cell in response to mechanical signals, as evidenced by a transient increase in focal adhesion (FA) number and increased RhoA activity. Preventing FA assembly or development of tension blocks activation of Akt by mechanical signals, but not by insulin. This indicates that the FA infrastructure is essential to the physical, but not necessarily the chemical, sensitivity, and responsiveness of the cell. Exploiting the transient nature of cytoskeletal remodeling may represent a process to enhance cell responsiveness to mechanical input and ultimately define the fate of MSCs with a minimal input.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Mallik A, Sen B, Banerjee M, Michailidis G. Threshold estimation based on a p-value framework in dose-response and regression settings. Biometrika 2011; 98:887-900. [PMID: 23049132 DOI: 10.1093/biomet/asr051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We use p-values to identify the threshold level at which a regression function leaves its baseline value, a problem motivated by applications in toxicological and pharmacological dose-response studies and environmental statistics. We study the problem in two sampling settings: one where multiple responses can be obtained at a number of different covariate levels, and the other the standard regression setting involving limited number of response values at each covariate. Our procedure involves testing the hypothesis that the regression function is at its baseline at each covariate value and then computing the potentially approximate p-value of the test. An estimate of the threshold is obtained by fitting a piecewise constant function with a single jump discontinuity, known as a stump, to these observed p-values, as they behave in markedly different ways on the two sides of the threshold. The estimate is shown to be consistent and its finite sample properties are studied through simulations. Our approach is computationally simple and extends to the estimation of the baseline value of the regression function, heteroscedastic errors and to time series. It is illustrated on some real data applications.
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Affiliation(s)
- A Mallik
- Department of Statistics, University of Michigan, Ann Arbor, Michigan 48109, U.S.A.,
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Case N, Thomas J, Sen B, Styner M, Xie Z, Galior K, Rubin J. Mechanical regulation of glycogen synthase kinase 3β (GSK3β) in mesenchymal stem cells is dependent on Akt protein serine 473 phosphorylation via mTORC2 protein. J Biol Chem 2011; 286:39450-6. [PMID: 21956113 DOI: 10.1074/jbc.m111.265330] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mechanical signals can inactivate glycogen synthase kinase 3β (GSK3β), resulting in stabilization of β-catenin. This signaling cascade is necessary for the inhibition of adipogenesis in mesenchymal stem cells (MSC) that is produced by a daily strain regimen. We investigated whether Akt is the mechanically activated kinase responsible for phosphorylation and inactivation of GSK3β in MSC. Mechanical strain (2% magnitude, 0.17 Hz) induced phosphorylation of Akt at Ser-473 and Thr-308 in parallel with phosphorylation of GSK3β at Ser-9. Inhibiting Akt (Akt1/2 kinase inhibitor treatment or Akt knockdown) prevented strain-induced phosphorylation of GSK3β at Ser-9. Inhibition of PI3K prevented Thr-308 phosphorylation, but strain-induced Ser-473 phosphorylation was measurable and induced phosphorylation of GSK3β, suggesting that Ser-473 phosphorylation is sufficient for the downstream mechanoresponse. As Rictor/mTORC2 (mammalian target of rapamycin complex 2) is known to transduce phosphorylation of Akt at Ser-473 by insulin, we investigated whether it contributes to strain-induced Ser-473 phosphorylation. Phosphorylation of Ser-473 by both mechanical and insulin treatment in MSC was prevented by the mTOR inhibitor KU0063794. When mTORC2 was blocked, mechanical GSK3β inactivation was prevented, whereas insulin inhibition of GSK3β was still measured in the absence of Ser-473 phosphorylation, presumably through phosphorylation of Akt at Thr-308. In sum, mechanical input initiates a signaling cascade that is uniquely dependent on mTORC2 activation and phosphorylation of Akt at Ser-473, an effect sufficient to cause inactivation of GSK3β. Thus, mechanical regulation of GSK3β downstream of Akt is dependent on phosphorylation of Akt at Ser-473 in a manner distinct from that of growth factors. As such, Akt reveals itself to be a pleiotropic signaling molecule whose downstream targets are differentially regulated depending upon the nature of the activating input.
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Affiliation(s)
- Natasha Case
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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