PI3 Kinase Isoforms in Purinergic Mesenchymal Stromal Cells

By using the transcriptom analysis it was demonstrated that mesemchymal stromal cells (MSCs) from the human adipose tissue express alpha-, beta-, and delta-isoforms of PI3 kinase (PI3K) from class I, while the PI3K gamma isoform is not expressed. The contribution of PI3K isoforms to purinergic transduction in MSCs was evaluated with the Ca2+-imaging approach and Ca2+ dye Fluo-4. As was shown, Ca2+ transients elicited by ATP in MSCs could be canceled by the PI3K alpha and PI3K beta inhibitors, GSK 1059615 and AZD 6482, respectively. The overall data indicated that most (69%) of MSCs were capable of generating robust ATP responses provided that PI3K alpha was sufficiently active. Yet, a small (15%) subpopulation of purinergic MSCs additionally employed the PI3K beta isoform to transduce extracellular ATP.