| 1. |
- Ihse, Elisabet, 1977-, et al.
(författare)
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Amyloid fibrils with fragmented ATTR may be the rule in non-Val30Met ATTR amyloidosis
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The clinical phenotype of familial ATTR amyloidosis depends to some extent on the particular mutation, but differences exist also within mutations. We have previously described that two types of amyloid fibril compositions exist among Swedish ATTRV30M amyloidosis patients, one consisting of a mixture of intact and fragmented ATTR (type A) and one composed of only intact ATTR (type B). Patients with type A fibrils have a late age of onset and signs of cardiomyopathy, while patients with type B fibrils have an early onset and much less myocardial involvement. The present study aimed to determine if the correlation between fibril type and clinical phenotype is true for familial amyloidosis in general. Cardiac and/or adipose tissue from 48 patients carrying 21 different non-TTRV30M mutations were examined, as well as 7 non-Swedish ATTRV30M patients. Fibril type was determined with western blotting and compared to the patients´ age of onset and degree of cardiomyopathy. Non-Swedish V30M patients showed the same correlation as described for Swedish V30M patients, with fibrils of only full-length ATTR (type B) linked to less myocardial involvement. In contrast, all patients with non-V30M mutations had a fibril composition with ATTR fragments (type A). Some of these patients had onset of disease at young age. The vast majority had increased thickness of left cardiac ventricle, but a few individuals had values within normal limits. This study shows that a fibril composition with fragmented ATTR is very common in ATTR amyloidosis. It also suggests that fibrils composed of only full-length ATTR is an exception, perhaps only found among young ATTRV30M amyloidosis patients.
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| 2. |
- Gezelius, Henrik, 1977-, et al.
(författare)
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Conditional genetic labeling of the Renshaw cell population for functional studies of motor control
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The Renshaw cells were among the first interneurons to be characterized in the mammalian spinal cord. Although the basic function of recurrent inhibition to motor neurons, as well as the Renshaw cell connectivity to other neurons have been thoroughly studied, the exact functional role of the Renshaw cells in motor control is still unknown. To further characterize the role of Renshaw cells in spinal cord circuitry, we searched for candidate genes useful in the Cre-loxP system. It has been reported that the mRNA expression of nicotinic cholinergic receptor alpha 2 (Chrna2) is found in a restricted number of cells at the ventral rim in adult rat and mouse spinal cord. In our own search for genes with distinct ventral expression, we noted a similar restricted Chrna2 mRNA expression pattern in the mouse spinal cord at postnatal day (P) 11 and during development at embryonic day 14.5. Based on the fact that the gene product is a cholinergic receptor and the pattern of expression, the neurons are predicted to be Renshaw cells. The possibility that these cells were motor neurons was excluded, since Chrna2 and Vesicular acetylcholine were not co-expressed at P11. To further study this cell population, we have generated a transgenic mouse expressing Cre recombinase (Cre) under the control of the Chrna2 promoter region. To visualize the Cre-expressing cells, the Chrna2-Cre transgenic mouse were bred with a reporter mouse expressing β-galactosidase (β-gal) in the nucleus after loxP excision. As expected, spinal cord β-gal immunoreactivity was observed in a limited number of ventrally located cells in the Cre-bearing offspring. Co-labeling of β-gal with calbindin-28K, a known marker for Renshaw cells, indicated that a majority of the calbindin positive cells were also β-gal positive at the ventral rim where calbindin is specific. In addition, β-gal positive cells without observable calbindin were also detected. It is conceivable that Chrna2 is expressed in additional cells apart from Renshaw cells or that a previously unidentified Renshaw cell subpopulation does not express calbindin. Nonetheless, a mouse with Cre-activity restricted to Chrna2-expressing cells opens the possibility to functionally study a limited population of spinal cord interneurons through genetic techniques, with the ambition to explore the specific role of Renshaw cells in spinal cord circuitry and motor control.
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| 3. |
- Karén, Jakob, 1973-, et al.
(författare)
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Effects of the HDAC inhibitor valproic acid on human pericytes in vitro
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Microvasculare pericytes are of key importance in neoformation of blood vessels, in stabilization of newly formed vessels as well as maintenance of angiostasis in resting tissues. In the present study the effects of the HDAC inhibitor VPA on pericyte proliferation, migration and differentiation was investigated. Furthermore, expression of genes known to be involved in different aspects of angiogenesis were investigated in primary pericyte cultures as well as the effects of VPA on the expression of these set of genes using quantative PCR arrays. The results show that HDAC inhibition leads to inhibition of pericyte proliferation and migration as well as pericyte differentiation into collagen type I producing fibroblasts. Furthermore, HDAC inhibition promoted expression of mRNAs of genes involved in vessel stabilization/maturation in human microvascular pericytes. The present study suggests that VPAs effect on angiogenesis via microvascular pericytes is through vessel stabilization.
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| 4. |
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| 5. |
- Karén, Jakob, 1973-, et al.
(författare)
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Defining the pericyte to fibroblast lineage
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In the present study placental tissues were characterized in vivo with regards to markers expressed on pericytes, fibroblasts and collagen type I synthesis. Microvascular fragments (MVFs) isolated from human placentas had a phenotypical marker profile consistent with microvessels in situ. Cells emerging from MVFs from placenta express a marker profile consistent with a pericyte phenotype. Temporal studies identified three optimal time points (T0, T1 and T2) subsequent to the onset of cells emerging from MVFs for further analysis with regards to divergence in marker expression profiles. T0, T1 and T2 time points contained a population of cells with a cellular phenotype consistent with mesenchymal stem/progenitor cells, activated microvascular pericytes and mature connective tissue cells. Three discernable subpopulations of cells were identified i.e. Stro-1+/CD146+/podoplanin-, Stro-1-/CD146+/podoplanin- and Stro-1-/CD146-/podoplanin+ cells. Flow cytometry analysis allowed for the Stro-1-/CD146+/podoplanin- and Stro-1-/CD146-/podplanin+ cell populations to be further divided into 2 subgroups based on the expression of desmin, αSMA and TE-7. Five steps in the differentiation process from mesenchymal stem/progenitor cell to collagen type I producing fibroblast and the order by which they progressed could be defined by re-diversification studies i.e. ability of one population of cells to give rise to the other population of cells. Two in vivo experimental systems, TPA induced inflammation and excisional cutaneous wound healing were analyzed for the existence of slow cycling cells. The in vivo evidence shows that microvascular pericytes constitute a reservoir of stem/progenitor cells for pro-fibrotic connective tissue cells. This study presents novel evidence for a connective tissue cell lineage originating from a undifferentiated mesenchymal vessel associated cell population that via pericytes differentiate into pro-fibrotic fibroblasts.
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| 6. |
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| 7. |
- Hamisi, Mariam, 1976-, et al.
(författare)
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Cyanobacteria associated with the phyllosphere of the seagrass Cymodocea rotundata: Diversity, diel nifH expression and nitrogenase activity : Diversity, nifH expression and activity in seagrass
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Tropical seagrass ecosystems are highly productive and extremely important for sustaining marine life. As seagrasses are associated with complex assemblages of poorly examined epiphytic microbes, we proposed that nitrogen-fixing microorganisms may contribute to the productivity. The morphological and genetic diversity (based on the 16S rRNA and nifH genes) of cyanobacteria and diel variations in nifH gene expression, NifH protein levels and nitrogenase (nitrogen-fixing) activity were examined in the phyllosphere of Cymodocea rotundata of coastal areas of the western Indian Ocean (Tanzania). The 16S rRNA and nifH gene analyses during two consecutive years (October-November, 2007 and 2008) revealed the dominance of a mixed cyanobacterial community. Most sequences represented free-living uncultured cyanobacteria previously reported as benthic in the region, clearly separated from marine planktonic phylotypes, while a few sequences clustered with cyanobacterial symbionts of diatoms. Appreciable, but varying nitrogenase activities were found on a diel as well as monthly basis, with the highest activity encountered, 358 ± 232 and 258 ± 139 nmol C2H4 g-1 h-1, in November. On a diel basis, nifH gene expression coincided with the NifH protein level (Oct 2008) and nitrogenase activity. At day time, nifH gene expression primarily originated from heterocystous phylotypes, while from non-heterocystous filamentous phylotypes (mainly Oscillatoriales) at night. The data suggest that a variety of diazotrophic cyanobacteria are common among the epiphytes on Cymodocea and we propose that these may represent a valuable source of ‘new’ nitrogen in the often oligotrophic, but ecologically important seagrass ecosystems.
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| 8. |
- Sylwan, Lina, et al.
(författare)
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Identification of bases required for P2 Integrase core-binding and recombination
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Temperate coliphage P2 integrates its genome into the host chromosome upon lysogenization via a site-specific recombination event mediated by an integrase belonging to the complex family of tyrosine recombinases. The host integration site attB (BOB´) is localized in the end of the cyaR gene and share 27 nucleotides with the core of attP (COC´). In the present study we determine the minimal attB site using an in vivo recombination assay and 10 nt on the left side (B) are found to be nonessential for recombination. We show that the integrase has higher affinity for the right side (B´) compared to B and that artificial B´OB´ and an attP site with a matching core (C´OC´) are efficient substrates for recombination in vitro. We have analyzed single nucleotides in attB and find that sequence homology within a non-centrally located quadruplet in the hypotetical overlap region is essential for efficient recombination in vivo.
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| 9. |
- Gunja, Sethu Madhava Rao, 1986-, et al.
(författare)
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PARN acts as a maternal factor required for normal embryogenesis and telomere length maintenance in zebrafish
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Poly(A)-specific ribonuclease (PARN) is a 3’-5’ exoribonuclease that removes poly(A) tails of mRNAs and ncRNAs in eukaryotes. Mutations in the human PARN gene are associated with developmental delay and/or telomere biology disorders (TBDs). Here we have established a parn loss-of-function zebrafish model that recapitulates TBD symptoms and phenotypes displayed in human patients. Homozygous parn deficient zebrafish exhibited aberrant snoRNA profile, telomerase RNA maturation and shortening of telomere length over generations. In addition, we found that zygotic parn mutant embryos (Zparn) generated by crossing homozygous male and heterozygous females developed a spectrum of growth/developmental defects from embryonic stage to adult stage. The mutant embryos showed developmental defects with lethality during blastula and gastrulation where the maternal mRNAs need to be destabilized with the activation of zygotic transcription; larvae that surpassed the embryonic stage developed severe developmental defects like bent tail and cardiac edema; the fish that survived to adulthood have severe growth defects. Overall, the array of disease phenotypes observed in PARN mutant fish explains the importance of PARN at different stages of life and could provide a link to the mechanism of TBD penetrance in humans.
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| 10. |
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