Delayed Osteoblastic Differentiation and Bone Development in Cx43 Knockout Mice

Abstract

GJA1 gene (Connexin43, also known as Cx43) is the most abundant gap junction protein isoform in animal cells and is associated with bone development in embryos. The objective of the present work was to evaluate in vivo osteal development in GJA1-deficient fetal mice through determination of the histological and molecular alterations induced by partial or total deletion of the GJA1 gene. Heterozygous C57BL/6 mice (HT) harboring a null mutation of the GJA1 gene were mated, and pregnant females were submitted to euthanasia and Caesarean section from 12.5 to 19.5 days post coitum (dpc). HT (GJA1 þ/-) and homozygous (GJA1 -/-) knockout (KO) mutants and wild-type (WT) fetuses were identified by polymerase chain reaction (PCR), and development curves were constructed on the basis of fetus weight and crown-rump length. Histopathological, histochemical, and realtime PCR analyses were performed in order to assess the expression of markers associated with bone development, namely, osteocalcin, osteopontin, alkaline phosphatase, RUNX2, GJA1, GJC1 (Cx45), and GJA3 (Cx46). HT and KO fetuses exhibited delays in the differentiation of osteoblasts and, consequently, in bone development in comparison with the WT group. Additionally, less deposition of mineralized and osteoid matrix was observed in GJA1-deficient fetuses. Bone development in KO fetuses was delayed through the moment of birth, but in HT animals the delay only extended until 17.5 dpc, following which development was normalized. The expression of genes coding for osteocalcin, osteopontin, alkaline phosphatise, and RUNX2 were also delayed in GJA1-deficient fetuses. Animals that exhibited a lower expression of GJA1 presented delayed expression of the GJC1 and GJA3 genes and their corresponding protein products in the bone tissue. The results of the present study contribute to our understanding of the function of GJA1 during bone development and suggest that GJC1 could play a role in restoring intercellular communication in GJA1-deficient mice.

Cell interactions between human progenitor-derived endothelial cells and human mesenchymal stem cells in a three-dimensional macroporous polysaccharide-based scaffold promote osteogenesis

“…Cx43 is most closely associated with the initiation of osteogenesis and bone formation. The role of Cx43 in osteogenesis and bone formation has been demonstrated in vitro using 2-D culture models of different osteoblastic cell lines [18] and in vivo using experimental models in mice [36]. In vitro, the present authors' previous results provide evidence of the function of endothelial cell interactions via gap junctional communication for the development of bone-forming cells [18,21,37].…”

Female mice lacking p47phoxhave altered adipose tissue gene expression and are protected against high fat-induced obesity

“…In addition, other pro-osteoblastic genes, Ihh (Indian hedgehog) (10) and four-and-a half LIM 2 (Fhl2) (9,16), were elevated in the P47KO HFD group compared with the WT:HFD group. Gja1 (gap junction protein alpha 1, connexin 36), another regulator of osteoblast development (3,22), was also elevated in the P47KO HFD group (Fig. 10).…”

Connexin43 Is Required for the Maintenance of Multipotency in Skin-Derived Stem Cells

“…Gap junctions have been shown to play a critical role in many developmental events such as cellular proliferation, apoptosis, differentiation, and organogenesis [2][3][4][5]. Connexin43 (Cx43) is considered the most widely expressed connexin and has been shown to play critical roles in many organ systems including folliculogenesis in the ovary, development and function of the heart, and osteoblast differentiation in bone development, among others [5][6][7][8][9][10]. Along with its role in organ development and function, the increased expression of Cx43 has been shown to decrease the proliferation and invasiveness of many cancer cells [11][12][13].…”