TY  - JOUR
A1  - Seefried, Lothar
A1  - Mueller-Deubert, Sigrid
A1  - Schwarz, Thomas
A1  - Lind, Thomas
A1  - Mentrup, Birgit
A1  - Kober, Melanie
A1  - Docheva, Denitsa
A1  - Liedert, Astrid
A1  - Kassem, Moustapha
A1  - Ignatius, Anita
A1  - Schieker, Matthias
A1  - Claes, Lutz
A1  - Wilke, Winfried
A1  - Jakob, Franz
A1  - Ebert, Regina
T1  - A small scale cell culture system to analyze mechanobiology using reporter gene constructs and polyurethane dishes
N2  - Mechanical forces are translated into biochemical signals and contribute to cell differentiation and phenotype maintenance. Mesenchymal stem cells and their tissuespecific offspring, as osteoblasts and chondrocytes, cells of cardiovascular tissues and lung cells are sensitive to mechanical loading but molecules and mechanisms involved have to be unraveled. It is well established that cellular mechanotransduction is mediated e.g. by activation of the transcription factor SP1 and by kinase signaling cascades resulting in the activation of the AP1 complex. To investigate cellular mechanisms involved in mechanotransduction and to analyze substances, which modulate cellular mechanosensitivity reporter gene constructs, which can be transfected into cells of interest might be helpful. Suitable small-scale bioreactor systems and mechanosensitive reporter gene constructs are lacking. To analyze the molecular mechanisms of mechanotransduction and its crosstalk with biochemically induced signal transduction, AP1 and SP1 luciferase reporter gene constructs were cloned and transfected into various cell lines and primary cells. A newly developed bioreactor and small-scale 24-well polyurethane dishes were used to apply cyclic stretching to the transfected cells. 1 Hz cyclic stretching for 30 min in this system resulted in a significant stimulation of AP1 and SP1 mediated luciferase activity compared to unstimulated cells. In summary we describe a small-scale cell culture/bioreactor system capable of analyzing subcellular crosstalk mechanisms in mechanotransduction, mechanosensitivity of primary cells and of screening the activity of putative mechanosensitizers as new targets, e.g. for the treatment of bone loss caused by both disuse and signal transduction related alterations of mechanotransduction.
KW  - Bioreaktor
KW  - Mechanical strain
KW  - mechanosensitive reporter
KW  - gene constructs
KW  - bioreactor
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68099
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  -