| 1. |
- Asadi, Abolfazl, 1950-
(författare)
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Identification and characterisation of the novel mammalian gene family Elovl
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Comparative analysis is one of the foremost tools in biology. The most common comparative method is sequence alignment, which can be performed in many ways. By using any sort of alignments, competing sequences are evaluated by scoring schemes for estimating similarity. The effectiveness of database searches is dependent on a large number of correlative factors. There are many equivalent DNA and protein sequence databases. It may be useful to restrict the search to a main database.In searching for similarity, the amino acid sequence derived from the DNA sequence is more informative than the DNA sequence. When proteins are analysed, they are divided into their compact globular structures, such as domains. Domains are used as the units of protein classification. Proteins are also clustered into families and superfamilies whose members have diverged from common ancestral forms. There are other types of protein classification that consider both sequence similarity and structural similarity. Based on these similarities, multiple databases have been constructed with different focuses.Most protein families can be characterised by sets of locally similar sequence segments, referred to as patterns and motifs. The detection of homology between a newly-determined sequence and a sequence motif in a protein databank is often the most important clue to the function of a geneThis thesis summarises the identification and characterisation of a novel mammalian gene family. As a common strategy for the genes presented here, full-length cDNAs were isolated, sequenced, the genomic structures characterised and the expression patterns analysed. Moreover, the existence of homologous genes in databanks extends the family to other eukaryotic organisms. The detection of homology between the gene families suggests a functional equivalency among the gene families. By complementation studies in yeast mutants, we found that homologous genes from a mouse gene family could rescue the yeast mutants lacking the ability to synthesis very long chain fatty acids and sphingolipids.In conclusion, this study presents the identification and characterisation of a gene family in which mutations can have pathogenic consequences and provides evidence that the members of this mouse gene family participate in the process of very long chain fatty acid synthesis.
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| 2. |
- González-Bengtsson, Amanda, et al.
(författare)
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Estrogen Enhances the Expression of the Polyunsaturated Fatty Acid Elongase Elovl2 via ERa in Breast Cancer Cells
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Endocrine therapy is the first-line targeted adjuvant therapy for hormone-sensitive breast cancer. In view of the potential anticancer property of the omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) together with chemotherapy in estrogen receptor alpha (ER alpha) positive mammary tumors, we have explored the regulation by estradiol of the fatty acid desaturation and elongation enzymes involved in DHA synthesis in the human breast cancer cell line MCF7, which expresses ER alpha but not ER beta. We demonstrate a robust up-regulation in the expression of the fatty acid elongases Elovl2 and Elovl5 upon estradiol stimulation in MCF7 cells, which was sustained for more than 24 hours. Exposure with the ER inhibitor tamoxifen abolished specifically the Elovl2 but not the Elovl5 expression. Similarly, knockdown of ER alpha eliminated almost fully the Elovl2 but not the Elovl5 expression. Furthermore, ER alpha binds to one specific ERE within the Elovl2 enhancer in a ligand dependent manner. The involvement of ER alpha in the control of especially Elovl2, which plays a crucial role in DHA synthesis, may have potential implications in the treatment of breast cancer.
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| 3. |
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| 4. |
- Hedman, Erik, et al.
(författare)
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Proteomic identification of glucocorticoid receptor interacting proteins
- 2006
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Ingår i: Proteomics. - : Wiley. - 1615-9853 .- 1615-9861. ; 6:10, s. 3114-26
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Tidskriftsartikel (refereegranskat)abstract
- The glucocorticoid receptor (GR) acts as a ligand dependent transcription factor but can also cross talk with other signaling pathways via protein-protein interactions. In this paper we describe methods to study novel cytosolic GR interacting proteins, using mAb based immunoaffinity chromatography of GR from rat liver cytosol. Co-purifying proteins were identified by 2-DE in combination with MALDI-TOF-MS. Non-liganded/non-activated and in vitro liganded/activated GR, respectively, co-purifies with specific sets of proteins. Of these 34 were conclusively identified, seven have previously been reported to be part of the GR-complex, revealing 27 new possible interacting candidates for the GR-complex. Of the novel GR interacting proteins the major vault protein, TATA binding interacting protein 49a and glycoprotein PP63 were of special interest. Furthermore, using 2-D DIGE we show that the set of proteins interacting with non-liganded GR is distinctly different in protein amount compared to the proteins found with liganded/activated GR. This suggests the presence of different GR complexes in the cell, which was further substantiated by the finding of several separate GR native protein complexes, "GR-receptosomes", using blue native gel electrophoresis. Our findings suggest the existence of several new mechanisms for GR signaling and regulation.
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| 5. |
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| 6. |
- Pauter, Anna M., et al.
(författare)
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Both maternal and offspring Elovl2 genotypes determine systemic DHA levels in perinatal mice
- 2017
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 58:1, s. 111-123
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Tidskriftsartikel (refereegranskat)abstract
- The molecular details relevant to dietary supplementation of the omega-3 fatty acid DHA in mothers as well as in their offspring are not clear. The PUFA elongase, elongation of very long-chain fatty acid (ELOVL) 2, is a critical enzyme in the formation of DHA in mammals. In order to address the question regarding the origin of DHA during perinatal life, we have used DHA-deficient Elovl2-ablated mice as a model system to analyze the maternal impact on the DHA level in their offspring of various genotypes. Elovl2(-/-) mothers maintained on control diet had significantly lower systemic levels of DHA compared with the Elovl2(+/-) and Elovl2(+/+) mothers. Dietary DHA administration during the pregnancy and lactation periods led to increased DHA accretion in maternal tissues and serum of all genotypes. The proportion of DHA in the liver and serum of the Elovl2(-/-) offspring was significantly lower than in the Elovl2(+/+) offspring. Remarkably, the DHA level in the Elovl2(+/-) offspring nursed by DHA-free-fed Elovl2(-/-) mothers was almost as high as in +/+ pups delivered by +/+ mothers, suggesting that endogenous synthesis in the offspring can compensate for maternal DHA deficiency.(Jlr) Maternal DHA supplementation had a strong impact on offspring hepatic gene expression, especially of the fatty acid transporter, Mfsd2a, suggesting a dynamic interplay between DHA synthesis and DHA uptake in the control of systemic levels in the offspring.
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| 7. |
- Pauter, Anna M., et al.
(författare)
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Elovl2 ablation demonstrates that systemic DHA is endogenously produced and is essential for lipid homeostasis in mice
- 2014
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 55:4, s. 718-728
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Tidskriftsartikel (refereegranskat)abstract
- The potential role of endogenously synthesized polyunsaturated fatty acids (PUFAs) is a highly overlooked area. Elongation of very long chain (ELOVL) fatty acids in mammals is catalyzed by the ELOVL enzymes to which the PUFA elongase ELOVL2 belongs. To determine its in vivo function, we have investigated how ablation of ELOVL2, which is highly expressed in liver, affects hepatic lipid composition and function in mice. The Elovl2 ablated mice displayed substantial decreased levels of 22:6(n3), docosahexaenoic acid (DHA), and 22:5(n6), docosapentaenoic acid (DPAn6), followed by an accumulation of 22:5(n3) and 22:4(n6) in both liver and serum showing that ELOVL2 primarily controls the elongation process of PUFAs with 22 carbons to produce 24 carbon precursors for DHA and DPA(n6) formation in vivo. The impaired PUFA levels positively influenced hepatic levels of the key lipogenic transcriptional regulator sterol regulatory element binding protein 1c (SREBP1c) as well as its downstream target genes. Surprisingly, the Elovl2 ablated mice were resistant against hepatic steatosis and diet induced weight gain implying that hepatic DHA synthesis via ELOVL2, except controlling de novo lipogenesis, also regulates lipid storage and fat mass expansion in an SREBP1c independent fashion. The changes in fatty acid metabolism were reversed by dietary supplementation with DHA.
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| 8. |
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| 9. |
- Pauter, Anna M., et al.
(författare)
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Synergistic Effects of DHA and Sucrose on Body Weight Gain in PUFA-Deficient Elovl2-/- Mice
- 2019
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Ingår i: Nutrients. - : MDPI AG. - 2072-6643. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- The omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) is implicated in the regulation of both lipid and carbohydrate metabolism. Thus, we questioned whether dietary DHA and low or high content of sucrose impact on metabolism in mice deficient for elongation of very long-chain fatty acids 2 (ELOVL2), an enzyme involved in the endogenous DHA synthesis. We found that Elovl2 -/- mice fed a high-sucrose DHA-enriched diet followed by the high sucrose, high fat challenge significantly increased body weight. This diet affected the triglyceride rich lipoprotein fraction of plasma lipoproteins and changed the expression of several genes involved in lipid metabolism in a white adipose tissue. Our findings suggest that lipogenesis in mammals is synergistically influenced by DHA dietary and sucrose content.
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| 10. |
- Rabionet, Mariona, et al.
(författare)
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Epidermal 1-O-acylceramides appear with the establishment of the water permeability barrier in mice and are produced by maturating keratinocytes
- 2022
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Ingår i: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 57:3, s. 183-195
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Tidskriftsartikel (refereegranskat)abstract
- 1-O-Acylceramides (1-OACs) have a fatty acid esterified to the 1-hydroxyl of the sphingosine head group of the ceramide, and recently we identified these lipids as natural components of human and mouse epidermis. Here we show epidermal 1-OACs arise shortly before birth during the establishment of the water permeability barrier in mice. Fractionation of human epidermis indicates 1-OACs concentrate in the stratum corneum. During in vitro maturation into reconstructed human epidermis, human keratinocytes dramatically increase 1-OAC levels indicating they are one source of epidermal 1-OACs. In search of potential enzymes responsible for 1-OAC synthesis in vivo, we analyzed mutant mice with deficiencies of ceramide synthases (Cers2, Cers3, or Cers4), diacylglycerol acyltransferases (Dgat1 or Dgat2), elongase of very long fatty acids 3 (Elovl3), lecithin cholesterol acyltransferase (Lcat), stearoyl-CoA desaturase 1 (Scd1), or acidic ceramidase (Asah1). Overall levels of 1-OACs did not decrease in any mouse model. In Cers3 and Dgat2-deficient epidermis they even increased in correlation with deficient skin barrier function. Dagt2 deficiency reshapes 1-OAC synthesis with an increase in 1-OACs with N-linked non-hydroxylated fatty acids and a 60% decrease compared to control in levels of 1-OACs with N-linked hydroxylated palmitate. As none of the single enzyme deficiencies we examined resulted in a lack of 1-OACs, we conclude that either there is functional redundancy in forming 1-OAC and more than one enzyme is involved, and/or an unknown acyltransferase of the epidermis performs the final step of 1-OAC synthesis, the implications of which are discussed.
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