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  - 
TY  - JOUR
A1  - Korkmaz, Yüksel
A1  - Puladi, Behrus
A1  - Galler, Kerstin
A1  - Kämmerer, Peer W.
A1  - Schröder, Agnes
A1  - Gölz, Lina
A1  - Sparwasser, Tim
A1  - Bloch, Wilhelm
A1  - Friebe, Andreas
A1  - Deschner, James
T1  - Inflammation in the human periodontium induces downregulation of the α\(_1\)- and β\(_1\)-subunits of the sGC in cementoclasts
JF  - International Journal of Molecular Sciences
N2  - Nitric oxide (NO) binds to soluble guanylyl cyclase (sGC), activates it in a reduced oxidized heme iron state, and generates cyclic Guanosine Monophosphate (cGMP), which results in vasodilatation and inhibition of osteoclast activity. In inflammation, sGC is oxidized and becomes insensitive to NO. NO- and heme-independent activation of sGC requires protein expression of the α\(_1\)- and β\(_1\)-subunits. Inflammation of the periodontium induces the resorption of cementum by cementoclasts and the resorption of the alveolar bone by osteoclasts, which can lead to tooth loss. As the presence of sGC in cementoclasts is unknown, we investigated the α\(_1\)- and β\(_1\)-subunits of sGC in cementoclasts of healthy and inflamed human periodontium using double immunostaining for CD68 and cathepsin K and compared the findings with those of osteoclasts from the same sections. In comparison to cementoclasts in the healthy periodontium, cementoclasts under inflammatory conditions showed a decreased staining intensity for both α\(_1\)- and β\(_1\)-subunits of sGC, indicating reduced protein expression of these subunits. Therefore, pharmacological activation of sGC in inflamed periodontal tissues in an NO- and heme-independent manner could be considered as a new treatment strategy to inhibit cementum resorption.
KW  - nitric oxide
KW  - soluble guanylyl cyclase
KW  - cGMP
KW  - cementoclasts
KW  - cementum
KW  - osteoclasts
KW  - alveolar bone
KW  - periodontitis
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285783
SN  - 1422-0067
VL  - 22
IS  - 2
ER  -