| 1. |
- Fonseca, Ana Catarina R. G., et al.
(författare)
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Calcineurin is an important factor involved in glucose uptake in human adipocytes
- 2018
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Ingår i: Molecular and Cellular Biochemistry. - : SPRINGER. - 0300-8177 .- 1573-4919. ; 445:1-2, s. 157-168
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Tidskriftsartikel (refereegranskat)abstract
- Calcineurin inhibitors are used in immunosuppressive therapy applied after transplantation, but they are associated with major metabolic side effects including the development of new onset diabetes. Previously, we have shown that the calcineurin inhibiting drugs tacrolimus and cyclosporin A reduce adipocyte and myocyte glucose uptakes by reducing the amount of glucose transporter type 4 (GLUT4) at the cell surface, due to an increased internalization rate. However, this happens without alteration in total protein and phosphorylation levels of key proteins involved in insulin signalling or in the total amount of GLUT4. The present study evaluates possible pathways involved in the altered internalization of GLUT4 and consequent reduction of glucose uptake provoked by calcineurin inhibitors in human subcutaneous adipose tissue. Short- and long-term treatments with tacrolimus, cyclosporin A or another CNI deltamethrin (herbicide) decreased basal and insulin-dependent glucose uptake in adipocytes, without any additive effects observed when added together. However, no tacrolimus effects were observed on glucose uptake when gene transcription and protein translation were inhibited. Investigation of genes potentially involved in GLUT4 trafficking showed only a small effect on ARHGEF11 gene expression (p < 0.05). In conlusion, the specific inhibition of calcineurin, but not that of protein phosphatases, decreases glucose uptake in human subcutaneous adipocytes, suggesting that calcineurin is an important regulator of glucose transport. This inhibitory effect is mediated via gene transcription or protein translation; however, expression of genes potentially involved in GLUT4 trafficking and endocytosis appears not to be involved in these effects.
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| 2. |
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| 3. |
- Lasch, Manuel, et al.
(författare)
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Estimating hemodynamic shear stress in murine peripheral collateral arteries by two-photon line scanning
- 2019
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Ingår i: Molecular and Cellular Biochemistry. - : Springer Nature. - 0300-8177 .- 1573-4919. ; 453, s. 41-51
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Tidskriftsartikel (refereegranskat)abstract
- Changes in wall shear stress of blood vessels are assumed to be an important component of many physiological and pathophysiological processes. However, due to technical limitations experimental in vivo data are rarely available. Here, we investigated two-photon excitation fluorescence microscopy as an option to measure vessel diameter as well as blood flow velocities in a murine hindlimb model of arteriogenesis (collateral artery growth). Using line scanning at high frequencies, we measured the movement of blood cells along the vessel axis. We found that peak systolic blood flow velocity averaged 9 mm/s and vessel diameter 42 µm in resting collaterals. Induction of arteriogenesis by femoral artery ligation resulted in a significant increase in centerline peak systolic velocity after 1 day with an average of 51 mm/s, whereas the averaged luminal diameter of collaterals (52 µm) changed much less. Thereof calculations revealed a significant fourfold increase in hemodynamic wall shear rate. Our results indicate that two-photon line scanning is a suitable tool to estimate wall shear stress e.g., in experimental animal models, such as of arteriogenesis, which may not only help to understand the relevance of mechanical forces in vivo, but also to adjust wall shear stress in ex vivo investigations on isolated vessels as well as cell culture experiments.
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| 4. |
- Nahálková, Jarmila
(författare)
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Novel protein-protein interactions of TPPII, p53, and SIRT7
- 2015
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Ingår i: Molecular and Cellular Biochemistry. - : Springer Science and Business Media LLC. - 0300-8177 .- 1573-4919. ; 409:1-2, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- Novel protein-protein interactions of TPPII, SIRT7, and p53 were detected by co-immunoprecipitation using both HeLa cell lysates and the cytoplasmic fraction prepared by fractionation of mouse liver tissue. The interactions were further verified in vivo by in situ proximity ligation assay (PLA) within control HEK293 cells transformed with empty vector, highactTPPII HEK293 cells over-expressing murine TPPII displaying high specific enzymatic activity and in lowactTPPII HEK293 cells over-expressing human TPPII having low specific activity of the enzyme. Besides an abundant cytoplasmic localization of TPPII-p53 interaction signal, the nuclear interactions were also demonstrated. The cytoplasmic interactions were likewise detected between TPPII and SIRT7 in control HEK293 and lowactTPPII HEK293 cells. The interactions of SIRT7 with p53 were confirmed in three HEK293 cell transformants as well. The cytoplasmic occurrence of SIRT7 protein was demonstrated by immunofluorescence, when both nucleolar and cytoplasmic signals were identified within HEK293 cells and primary human fibroblasts. The unique cytoplasmic localization of SIRT7 protein was discussed based on an epitope specificity of N-terminus specific SIRT7 antibodies utilized in the present study compared with C-terminus specific antibodies previously used for nuclear detection of SIRT7 by other authors. The epitope sequence of N-terminal antibodies is occurring in all three splicing variants of SIRT7 compared to the epitope of C-terminal antibody, which is specific exclusively to the splicing variant 1. The cytoplasmic localization of p53 detected by immunofluorescence supported the results from its interactions with TPPII and SIRT7 observed by in situ PLA within model cells. Novel interactions of TPPII, p53, and SIRT7 presented in this study might contribute to the knowledge of the regulatory effects of these proteins on apoptotic pathways and to the understanding mechanisms of aging and lifespan regulation.
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| 5. |
- Nahálková, Jarmila
(författare)
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The protein-interaction network with functional roles in tumorigenesis, neurodegeneration, and aging
- 2016
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Ingår i: Molecular and Cellular Biochemistry. - : Springer Science and Business Media LLC. - 0300-8177 .- 1573-4919. ; 423:1-2, s. 187-196
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Forskningsöversikt (refereegranskat)abstract
- The present review summarizes the knowledge about a protein-interaction network, which includes proteins with significant functions in the mechanisms of aging and age-related diseases. All the detected interacting proteins TPPII, p53, MYBBP1A, CDK2 and SIRT7, SIRT6, and CD147 are suitable for the development of antitumor therapeutics and treatments for diseases of aging. TPPII and SIRT6 directly affect glucose metabolism which drive malignant growth. In addition, SIRT6 activators are attractive candidates for Alzheimer's disease (AD) due to the protection effect of SIRT6 overexpression from DNA damage. TPPII activity exhibits a decreasing effect on mTOR signaling, and its requirement for the degradation of A beta peptides in the human fibroblasts suggests that it has dual functions in tumorigenesis and AD-related pathology. Likewise, the direct promotion of the invasiveness of breast epithelial cells and the contribution to the A beta degradation by stimulating the matrix metalloproteinases production suggest a double functional role for CD147. An association of the partial portion of cellular CD147 to gamma-secretase further supports the functional relation to AD pathology. The animal and cellular models with downregulated or knockout TPPII, p53, SIRT6, SIRT7, and MYBBP1A expression levels illustrate similar functions of the interacting proteins. They demonstrate similar effects on the length of life span, premature aging, and lipid metabolism. The presented protein-interaction network is relevant to the discoveries of the mechanisms of tumorigenesis, aging, and neurodegeneration.
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