K Dorshkind1, L Green, A Godwin
1Division of Biomedical Sciences, University of California, Riverside 92521-0121.
This study explored whether bone marrow stromal cells communicate through gap junctions. Researchers found that a fluorescent dye injected into one stromal cell spread to others, showing functional coupling. They also observed electrical connections between cells. Connexin 43 was identified as the likely mediator, while Cx26 and Cx32 were absent. When cells were treated with interleukin-1, dye transfer decreased, but the effect was reversible. No communication was seen between stromal and lymphoid cells. The results support the presence of regulated gap junctions in stromal cell interactions.
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Area of Science:
Background:
Prior research has shown that bone marrow stromal cells form physical connections. These connections may support interactions within the marrow. However, the nature of these links remained unclear. Some studies suggested the presence of gap junctions. Yet, no direct evidence existed for functional communication. Researchers had not yet tested if these junctions could transfer signals. The role of connexin proteins in this context was also unknown. This gap motivated investigations into stromal cell coupling.
Purpose Of The Study:
This study aimed to determine if stromal cells communicate via gap junctions. The researchers focused on the transfer of fluorescent dyes between cells. They also examined whether connexin 43 was involved in this process. A key question was whether cytokines could regulate this communication. The study tested the effect of interleukin-1 on dye transfer. The goal was to confirm the presence and regulation of gap junctions. Researchers also wanted to assess if lymphoid cells were involved. The study sought to clarify the role of stromal coupling in marrow function.
The study shows that stromal cells communicate via gap junctions, as evidenced by dye transfer and electrical coupling.
Connexin 43 is present in stromal cells, while Cx26 and Cx32 are not detected.
IL-1 was tested to determine if it could regulate gap junction permeability in stromal cells.
IL-1 treatment caused a reversible decrease in dye transfer between stromal cells.
No, the researchers found no evidence of communication between stroma and developing lymphoid cells.
Main Methods:
The researchers used primary bone marrow cultures and a stromal cell line. They microinjected lucifer yellow dye into individual stromal cells. They observed whether the dye spread to neighboring cells. They also measured electrical coupling between stromal cells. RNA was extracted to detect connexin transcripts. They specifically looked for Cx43, Cx26, and Cx32. Cells were treated with interleukin-1 to test regulation. Dye transfer was re-evaluated after cytokine exposure.
Main Results:
Lucifer yellow dye spread to most contacting stromal cells after injection. Electrical coupling was also observed between stromal cells. RNA analysis showed only Cx43 was present in the cell line. Cx26 and Cx32 transcripts were not detected. IL-1 treatment reduced dye transfer between stromal cells. This effect was reversible after cytokine removal. No communication was observed between stroma and lymphoid cells. The results support the presence of functional gap junctions.
Conclusions:
The study supports the presence of gap junctions between stromal cells. Connexin 43 appears to mediate this communication. IL-1 can regulate the permeability of these junctions. Dye transfer decreased after cytokine treatment. The effect was not permanent and reversed over time. No evidence of communication between stroma and lymphoid cells was found. These findings suggest stromal coupling is dynamic and modifiable. The role of this coupling in marrow function remains to be explored.
The findings suggest that stromal cell coupling is dynamic and may be regulated by cytokines.