| 1. |
- Ruge, Toralph, et al.
(författare)
-
Nutritional regulation of lipoprotein lipase in mice
- 2004
-
Ingår i: International Journal of Biochemistry and Cell Biology. - 1357-2725 .- 1878-5875. ; 36:2, s. 320-329
-
Tidskriftsartikel (refereegranskat)abstract
- Tissue-specific regulation of lipoprotein lipase (LPL) has been extensively studied in rats. The mouse is now the most used animal in lipoprotein research, and we have therefore explored the regulation of LPL in this species. In C57 black mice, fed ad libitum adipose tissue LPL activity changed about three-fold with the time of day, indicating a circadian rhythm. The highest activity was at midnight and the lowest activity was at noon. Withdrawal of food did not markedly accelerate the drop of activity that occurred from midnight until noon, but prevented the return of activity that occurred during the evening and early night. When food was returned to mice that had been fasted for 24h, adipose tissue LPL activity rose rapidly and returned to the fed level in 2h. LPL mass in adipose tissue changed less than LPL activity, indicating that regulation is mainly post-translational as previously demonstrated for rats. When transcription was blocked in fasted mice, adipose tissue LPL activity increased, as previously observed in rats. LPL activity in heart was highest early in the light period at 9:00h and lowest at 21:00h. The change was, however, only about 30%. Heparin-releasable LPL activity in heart was 1.8-fold higher in mice fasted for 6h compared to fed controls. We conclude that LPL activity responds to the nutritional state in the same direction and by the same mechanisms in mice as in rats, but the magnitude of the changes are less in mice.
|
|
| 2. |
- Sironen, Reijo, et al.
(författare)
-
Reticulon 4 in chondrocytic cells: barosensitivity and intracellular localization
- 2004
-
Ingår i: International Journal of Biochemistry and Cell Biology. - : Elsevier. - 1357-2725 .- 1878-5875. ; 36:8, s. 1521-31
-
Tidskriftsartikel (refereegranskat)abstract
- Members of the reticulon gene family are endoplasmic reticulum (ER)-related proteins expressed in various human tissues, but their molecular functions are not understood. The reticulon 4 subfamily consists of three members, reticulon 4/Nogo-A, -B and -C. Reticulon 4-A is under intense investigation because of its inhibitory effect on neurite outgrowth, and reticulon 4-B has been suggested to induce apoptosis. Reticulon 4-C, the shortest member of this subfamily, is the least characterized. Reticulons are presumably guided to endoplasmic reticulum by a putative N-terminal retention motif. In this study the expressions of reticulon 4 subtypes in human chondrosarcoma cell line and in primary bovine chondrocytes were analyzed on mRNA level. These cell types, exposed to strong mechanical forces in vivo, were subjected to high hydrostatic pressure and mechanical stretch to study the possible mechanosensitivity of reticulon 4 genes. In addition, a green fluorescent protein-tagged reticulon 4-C and a fusion protein with mutated endoplasmic reticulum retention signal were used to study the significance of the C-terminal translocation signal (the di-lysine motif). As the result, both cell types expressed the three main isoforms of reticulon 4 family. The steady-state level of reticulon 4-B mRNA was shown to be up-regulated by pressure, but not by mechanical stretch indicating transcriptional barosensitivity. The reticular distribution pattern of reticulon 4-C was observed indicating a close association with endoplasmic reticulum. Interestingly, this pattern was maintained despite of the disruption of the putative localization signal. This suggests the presence of another, yet unidentified endoplasmic reticulum retention mechanism.
|
|
| 3. |
- Terman, Alexei, et al.
(författare)
-
Aging as a catabolic malfunction
- 2004
-
Ingår i: International Journal of Biochemistry and Cell Biology. - : Elsevier BV. - 1357-2725 .- 1878-5875. ; 36:12, s. 2365-2375
-
Forskningsöversikt (refereegranskat)abstract
- Cellular degradative processes, which include lysosomal (autophagic) and proteasomal degradation, as well as catabolism of proteins by cytosolic and mitochondrial proteases, provide for a continuous turnover of cellular components, such as damaged or obsolete biomolecules and organelles. Inherent insufficiency of these degradative processes results in progressive accumulation within long-lived postmitotic cells of biological 'garbage' (waste material), such as various oxidized proteins, functionally effete mitochondria, and lipofuscin (age pigment), an intralysosomal, polymeric, undegradable material. There is increasing evidence that lipofuscin hampers lysosomal degradative capacity, thus promoting the aggravation of accumulated damage at old age. Being rich in redox-active iron, lipofuscin granules also may exacerbate oxidative stress levels in senescent cells. Thus, increasing the efficiency of cellular degradative pathways and preventing involvement of iron in oxidant-induced lysosomal and cellular damage may be potential strategies for anti-aging interventions. © 2004 Elsevier Ltd. All rights reserved.
|
|
| 4. |
- Terman, Alexei, 1957-, et al.
(författare)
-
Aging as a catabolic malfunction
- 2004
-
Ingår i: International Journal of Biochemistry and Cell Biology. - 1357-2725 .- 1878-5875. ; 36, s. 2365-2375
-
Tidskriftsartikel (refereegranskat)
|
|
| 5. |
- Terman, Alexei, et al.
(författare)
-
Lipofuscin
- 2004
-
Ingår i: International Journal of Biochemistry and Cell Biology. - : Elsevier BV. - 1357-2725 .- 1878-5875. ; 36:8, s. 1400-1404
-
Forskningsöversikt (refereegranskat)abstract
- Over time, postmitotic cells accumulate a non-degradable intralysosomal substance, lipofuscin, which forms due to iron-catalyzed oxidation/ polymerization of protein and lipid residues. Lipofuscin is often considered a hallmark of aging, showing an accumulation rate that inversely correlates with longevity. There is an emerging impression that lipofuscin, although still typically considered a harmless wear-and-tear product, may have multiple negative effects. By interfering with the important autophagic process, by which most worn out cellular components are degraded, it may prevent cellular renewal and advance the accumulation of damaged cellular constituents. Due to binding of transition metals, such as iron and copper, lipofuscin also seems to sensitize lysosomes and cells to oxidative stress. Of importance for the pathogenesis of age-related macular degeneration, lipofuscin deposition interferes with the phagocytic activity of retinal pigment epithelial cells and also sensitizes their lysosomes to blue light. © 2003 Published by Elsevier Ltd.
|
|
| 6. |
- Terman, Alexei, 1957-, et al.
(författare)
-
Lipofuscin
- 2004
-
Ingår i: International Journal of Biochemistry and Cell Biology. - 1357-2725 .- 1878-5875. ; 36, s. 1400-1404
-
Tidskriftsartikel (refereegranskat)
|
|
| 7. |
|
|
| 8. |
- Östergren Lundén, Gunnel, 1950, et al.
(författare)
-
Characterisation and application of antibodies specific for the long platelet-derived growth factor A and B chains.
- 2004
-
Ingår i: The international journal of biochemistry & cell biology. - : Elsevier BV. - 1357-2725 .- 1878-5875. ; 36:11, s. 2226-41
-
Tidskriftsartikel (refereegranskat)abstract
- The platelet-derived growth factor (PDGF) family comprises important mitogens for mesenchymal cells. The active dimeric form of PDGF consists of four structurally related A, B, C, and D chains. All PDGF-variants bind to PDGF-receptors. The A and B chains occur with and without basic C-terminal amino acid extensions as long (A(L) and B(L)) and short (A(S) and B(S)) isoforms. PDGF-A and -B form homo- or heterodimers. The biological relevance of short and long isoforms is unknown, although it may relate to different affinities for glycosaminoglycans of the cell glycocalix and intercellular matrix. Commercially available anti-PDGF-A and anti-PDGF-B antibodies cannot discriminate between the short and the long isoforms. Thus, to investigate the function of the long and short isoforms, we raised antibodies specific for the long A and B chain isoforms. The antibodies were affinity-purified and their properties analysed by surface plasmon resonance. Inhibition studies with different PDGF homodimers and dot-blot studies proved their high specificity for the respective isoforms. Both antibodies recognised the target PDGF homodimers complexed to the glycocalix of human arterial smooth muscle cells and human monocyte-derived macrophages. By using these specific antibodies, we were able to confirm at the protein level the synthesis of PDGF-A and -B during differentiation of human monocyte-derived macrophages and to demonstrate the presence of the PDGF-A(L) and PDGF-B(L) isoforms in human arterial tissue.
|
|
| 9. |
|
|
| 10. |
|
|
