Morphological evidence of gap junctions between bone cells

1981 ◽  
Vol 33 (1) ◽  
pp. 509-512 ◽  
Author(s):  
Stephen B. Doty
Keyword(s):  
Gap Junctions ◽  
Bone Cells ◽  
Morphological Evidence

scholarly journals Intercellular calcium wave propagation in linear and circuit-like bone cell networks

2010 ◽  
Vol 368 (1912) ◽  
pp. 617-633 ◽  
Author(s):  
Bo Huo ◽  
Xin L. Lu ◽  
X. Edward Guo
Keyword(s):  
Wave Propagation ◽  
Gap Junctions ◽  
Calcium Release ◽  
Bone Cells ◽  
Molecular Transport ◽  
Bone Cell ◽  
Calcium Wave ◽  
Contact Printing ◽  
Inhibition Studies ◽  
Cell Networks

In the present study, the mechanism of intercellular calcium wave propagation in bone cell networks was identified. By using micro-contact printing and self-assembled monolayer technologies, two types of in vitro bone cell networks were constructed: open-ended linear chains and looped hexagonal networks with precisely controlled intercellular distances. Intracellular calcium responses of the cells were recorded and analysed when a single cell in the network was mechanically stimulated by nano-indentation. The looped cell network was shown to be more efficient than the linear pattern in transferring calcium signals from cell to cell. This phenomenon was further examined by pathway-inhibition studies. Intercellular calcium wave propagation was significantly impeded when extracellular adenosine triphosphate (ATP) in the medium was hydrolysed. Chemical uncoupling of gap junctions, however, did not significantly decrease the transferred distance of the calcium wave in the cell networks. Thus, it is extracellular ATP diffusion, rather than molecular transport through gap junctions, that dominantly mediates the transmission of mechanically elicited intercellular calcium waves in bone cells. The inhibition studies also demonstrated that the mechanical stimulation-induced calcium responses required extracellular calcium influx, whereas the ATP-elicited calcium wave relied on calcium release from the calcium store of the endoplasmic reticulum.

scholarly journals Connexins and the kidney

2010 ◽  
Vol 298 (5) ◽  
pp. R1143-R1155 ◽  
Author(s):  
Fiona Hanner ◽  
Charlotte Mehlin Sorensen ◽  
Niels-Henrik Holstein-Rathlou ◽  
János Peti-Peterdi
Keyword(s):  
Gap Junctions ◽  
Purinergic Signaling ◽  
Renin Angiotensin System ◽  
Juxtaglomerular Apparatus ◽  
Tubuloglomerular Feedback ◽  
Current Evidence ◽  
Morphological Evidence ◽  
Renal Vasculature ◽  
Angiotensin System ◽  
Major Function

Connexins (Cxs) are widely-expressed proteins that form gap junctions in most organs, including the kidney. In the renal vasculature, Cx37, Cx40, Cx43, and Cx45 are expressed, with predominant expression of Cx40 in the endothelial cells and Cx45 in the vascular smooth muscle cells. In the tubules, there is morphological evidence for the presence of gap junction plaques only in the proximal tubules. In the distal nephron, Cx30, Cx30.3, and Cx37 are expressed, but it is not known whether they form gap junctions connecting neighboring cells or whether they primarily act as hemichannels. As in other systems, the major function of Cxs in the kidney appears to be intercellular communication, although they may also form hemichannels that allow cellular secretion of large signaling molecules. Renal Cxs facilitate vascular conduction, juxtaglomerular apparatus calcium signaling, and tubular purinergic signaling. Accordingly, current evidence points to roles for these Cxs in several important regulatory mechanisms in the kidney, including the renin angiotensin system, tubuloglomerular feedback, and salt and water reabsorption. At the systemic level, renal Cxs may help regulate blood pressure and may be involved in hypertension and diabetes.

Gap Junctions and Osteoblast-like Cell Gene Expression in Response to Fluid Flow

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Michael G. Jekir ◽  
Henry J. Donahue
Keyword(s):  
Fluid Flow ◽  
Gap Junctions ◽  
Gap Junction ◽  
Bone Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mrna Levels ◽  
Mechanical Stimuli ◽  
Junctional Communication ◽  
Osteogenic Response

Bone formation occurs in vivo in response to mechanical stimuli, but the signaling pathways involved remain unclear. The ability of bone cells to communicate with each other in the presence of an applied load may influence the overall osteogenic response. The goal of this research was to determine whether inhibiting cell-to-cell gap junctional communication between bone-forming cells would affect the ensemble cell response to an applied mechanical stimulus in vitro. In this study, we investigated the effects of controlled oscillatory fluid flow (OFF) on osteoblastic cells in the presence and the absence of a gap-junction blocker. MC3T3-E1 Clone 14 cells in a monolayer were exposed to 2h of OFF at a rate sufficient to create a shear stress of 20dynes∕cm2 at the cell surface, and changes in steady-state mRNA levels for a number of key proteins known to be involved in osteogenesis were measured. Of the five proteins investigated, mRNA levels for osteopontin (OPN) and osteocalcin were found to be significantly increased 24h postflow. These experiments were repeated in the presence of 18β-glycyrrhetinic acid (BGA), a known gap-junction blocker, to determine whether gap-junction intercellular communication is necessary for this response. We found that the increase in OPN mRNA levels is not observed in the presence of BGA, suggesting that gap junctions are involved in the signaling process. Interestingly, enzyme linked immunosorbent assay data showed that levels of secreted OPN protein increased 48h postflow and that this increase was unaffected by the presence of intact gap junctions.

scholarly journals Primary Osteocyte Supernatants Metabolomic Profiling of Two Transgenic Mice With Connexin43 Dominant Negative Mutants

2021 ◽  
Vol 12 ◽  
Author(s):  
Meng Chen ◽  
Guobin Li ◽  
Lan Zhang ◽  
Kaiting Ning ◽  
Baoqiang Yang ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Bone Cells ◽  
Dominant Negative ◽  
Regulatory Function ◽  
Metabolomic Profiling ◽  
Oxidative Stress Pathway ◽  
Liquid Chromatography Tandem Mass ◽  
Cx 43 ◽  
Fatty Acyls ◽  
Extracellular Environment

Osteocytes could release some small molecules (≤ 1 kDa) through gap junctions and hemichannels to extracellular environment, such as prostaglandin E2 (PGE2), nitric oxide (NO) and adenosine triphosphate (ATP), which play key roles in transferring signals between bone cells and other tissue cells. Connexin (Cx) 43 is the most abundant connexin in osteocytes. To further discover molecules released by osteocytes through Cx43 channels and better understand the regulatory function of Cx43 channels in osteocytes, we performed non-targeted global metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) on conditioned medium collected from osteocytes isolated from two transgenic mouse models with Cx43 dominant negative mutants driven by a 10 kb-DMP1 promoter: R76W (gap junctions are blocked, whereas hemichannels are promoted) and Δ130-136 (both gap junctions and hemichannels are blocked). The results revealed that several new categories of molecules, such as “fatty acyls” and “carboxylic acids and derivatives”, could be released through osteocytic Cx43 channels. In addition, alteration of Cx43 channel function affected the release of metabolites related to inflammatory reaction and oxidative stress. Pathway analysis further showed that citric acid cycle was the most differential metabolic pathway regulated by Cx43 channels. In sum, these results isolated new potential metabolites released by osteocytes through Cx43 channels, and offered a novel perspective to understand the regulatory mechanisms of osteocytes on themselves and other cells as well.

Effects of Lead, Mercury, and Methyl Mercury on Gap Junctions and [Ca2+]i in Bone Cells

1998 ◽  
Vol 63 (2) ◽  
pp. 134-139 ◽  
Author(s):  
K. Schirrmacher ◽  
M. Wiemann ◽  
D. Bingmann ◽  
D. Büsselberg
Keyword(s):  
Gap Junctions ◽  
Methyl Mercury ◽  
Bone Cells

The incidence and size of gap junctions between the bone cells in rat calvaria

1993 ◽  
Vol 187 (4) ◽  
Author(s):  
S.J. Jones ◽  
C. Gray ◽  
H. Sakamaki ◽  
M. Arora ◽  
A. Boyde ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Bone Cells ◽  
Rat Calvaria

scholarly journals Connexin 43 in osteogenesis

2020 ◽  
Vol 74 ◽  
pp. 406-415
Author(s):  
Krzysztof Łukowicz ◽  
Karolina Fijał ◽  
Aleksandra Nowak ◽  
Anna M. Osyczka
Keyword(s):  
Gap Junctions ◽  
Bone Tissue ◽  
Connexin 43 ◽  
Bone Cells ◽  
Mechanical Stimuli ◽  
Bone Homeostasis ◽  
Gene Encoding ◽  
Skeletal Defects ◽  
Turnover Process ◽  
Connexin Proteins

Skeleton formation and its proper functioning is possible thanks to specialized bone tissue cells: bone forming osteoblasts, bone resorbing osteoclasts and osteocytes located in bone cavities. Gap junctions are transmembrane channels connecting neighboring cell. Thanks to gap junctions it is possible for signals to be directly transmitted by cells. Gap junction type channels, and more specifically the connexin proteins that build them, have a key impacton the bone turnover process, and thus on both bone building and remodeling. A particularly important connexin in bone tissue is connexin43 (Cx43), which is necessary in the proper course of the bone formation process and in maintaining bone homeostasis. The importance of the presence of Cx43 in bones is showed by skeletal defects in diseases such as ODD syndrome and craniometaphyseal dysplasia caused by mutations in GJA1, the gene encoding Cx43. The role of Cx43 in the differentiation of stem cells into bone cells, anti-apoptotic action of bisphosphonates and bone responses to hormonal and mechanical stimuli have also been demonstrated. In addition to connexin43, the presence of other connexins such as connexin45, 46 and 37 was also noted in bone tissue.

Sign in / Sign up

Export Citation Format

Share Document