TY  - JOUR
A1  - Schröder, Wiebke
A1  - Bernhardt, Jörg
A1  - Marincola, Gabriella
A1  - Klein-Hitpass, Ludger
A1  - Herbig, Alexander
A1  - Krupp, Guido
A1  - Nieselt, Kay
A1  - Wolz, Christiane
T1  - Altering gene expression by aminocoumarins: the role of DNA supercoiling in Staphylococcus aureus
JF  - BMC Genomics
N2  - BACKGROUND:
It has been shown previously that aminocoumarin antibiotics such as novobiocin lead to immediate downregulation of recA expression and thereby inhibit the SOS response, mutation frequency and recombination capacity in Staphylococcus aureus. Aminocoumarins function by inhibiting the ATPase activity of DNA gyrase subunit B with a severe impact on DNA supercoiling.
RESULTS:
Here, we have analysed the global impact of the DNA relaxing agent novobiocin on gene expression in S. aureus. Using a novobiocin-resistant mutant, it became evident that the change in recA expression is due to gyrase inhibition. Microarray analysis and northern blot hybridisation revealed that the expression levels of a distinct set of genes were increased (e.g., recF-gyrB-gyrA, the rib operon and the ure operon) or decreased (e.g., arlRS, recA, lukA, hlgC and fnbA) by novobiocin. The two-component ArlRS system was previously found to decrease the level of supercoiling in S. aureus. Thus, downregulation of arlRS might partially compensate for the relaxing effect of novobiocin. Global analysis and gene mapping of supercoiling-sensitive genes did not provide any indication that they are clustered in the genome. Promoter fusion assays confirmed that the responsiveness of a given gene is intrinsic to the promoter region but independent of the chromosomal location.
CONCLUSIONS:
The results indicate that the molecular properties of a given promoter, rather than the chromosomal topology, dictate the responsiveness to changes in supercoiling in the pathogen Staphylococcus aureus.
KW  - aminocoumarins
KW  - novobiocin
KW  - microarray
KW  - Voronoi tree map
KW  - spacer
KW  - arlR
KW  - gyrase
KW  - supercoiling
KW  - staphylococcus aureus
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121609
SN  - 1471-2164
VL  - 15
IS  - 291
ER  - 
TY  - JOUR
A1  - Liedert, Astrid
A1  - Röntgen, Viktoria
A1  - Schinke, Thorsten
A1  - Benisch, Peggy
A1  - Ebert, Regina
A1  - Jakob, Franz
A1  - Klein-Hitpass, Ludger
A1  - Lennerz, Jochen K.
A1  - Amling, Michael
A1  - Ignatius, Anita
T1  - Osteoblast-Specific Krm2 Overexpression and Lrp5 Deficiency Have Different Effects on Fracture Healing in Mice
JF  - PLOS ONE
N2  - The canonical Wnt/beta-catenin pathway plays a key role in the regulation of bone remodeling in mice and humans. Two transmembrane proteins that are involved in decreasing the activity of this pathway by binding to extracellular antagonists, such as Dickkopf 1 (Dkk1), are the low-density lipoprotein receptor related protein 5 (Lrp5) and Kremen 2 (Krm2). Lrp 5 deficiency (Lrp5(-/-)) as well as osteoblast-specific overexpression of Krm2 in mice (Col1a1-Krm2) result in severe osteoporosis occurring at young age. In this study, we analyzed the influence of Lrp5 deficiency and osteoblast-specific overexpression of Krm2 on fracture healing in mice using flexible and semi-rigid fracture fixation. We demonstrated that fracture healing was highly impaired in both mouse genotypes, but that impairment was more severe in Col1a1-Krm2 than in Lrp5(-/-) mice and particularly evident in mice in which the more flexible fixation was used. Bone formation was more reduced in Col1a1-Krm2 than in Lrp5(-/-) mice, whereas osteoclast number was similarly increased in both genotypes in comparison with wild-type mice. Using microarray analysis we identified reduced expression of genes mainly involved in osteogenesis that seemed to be responsible for the observed stronger impairment of healing in Col1a1-Krm2 mice. In line with these findings, we detected decreased expression of sphingomyelin phosphodiesterase 3 (Smpd3) and less active beta-catenin in the calli of Col1a1-Krm2 mice. Since Krm2 seems to play a significant role in regulating bone formation during fracture healing, antagonizing KRM2 might be a therapeutic option to improve fracture healing under compromised conditions, such as osteoporosis.
KW  - autosomal-dominant osteopetrosis
KW  - receptor related protein
KW  - high-bone-mass
KW  - WNT pathway
KW  - in-vitro
KW  - cells
KW  - gene
KW  - proliferation
KW  - osteoclasts
KW  - mutations
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-115782
SN  - 1932-6203
VL  - 9
IS  - 7
ER  -