Constitutive lysosome exocytosis releases ATP and engages P2Y receptors in human monocytes

Venketesh Sivaramakrishnan, Stefan Bidula, Hinnah Campwala, Divya Katikaneni, Samuel Fountain

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Elucidating mechanisms by which Ca2+ signals are generated by monocytes is important for understanding monocyte function in health and disease. We have investigated mechanisms underlying Ca2+ signals generated following disruption of lysosomes by exposure to the cathepsin C substrate glycyl-L-phenylalanine-β-napthylamide (GPN). Exposure to 0.2 mM GPN resulted in robust increases in the intracellular Ca2+ concentration ([Ca2+]i) in the absence of extracellular Ca2+. The response was antagonised by thapsigargin and evoked capacitative Ca2+ entry. Dantrolene-sensitive Ca2+ responses were observed at higher concentrations of GPN (0.4 mM) but not at 0.2 mM. Strikingly, GPN-evoked Ca2+ responses and β-hexosaminidase secretion were inhibited by the ATPase/ADPase apyrase. Simultaneous measurement of [Ca2+]i and extracellular ATP revealed a concomitant secretion of ATP during GPN-evoked Ca2+ signalling. Furthermore, the ability of GPN to raise [Ca2+]i was inhibited by P2Y receptor antagonists or by inhibiting vesicular exocytosis with N-ethylmaleimide (NEM). NEM treatment was associated with an inability of GPN to trigger ATP secretion, a drop in baseline [Ca2+]i and reduction in extracellular ATP concentration. Antagonism of purinergic signalling also caused a reduction in baseline [Ca2+]i. In summary, these data suggest that P2Y receptor activation contributes significantly to GPN-evoked Ca2+ signalling, and that constitutive secretion of lysosomal ATP is a major determinant of Ca2+ homeostasis in monocytes. Lysosomal Ca2+ stores can communicate with ER Ca2+ stores either directly through activation of ryanodine receptors, or indirectly through release of ATP and engagement of P2Y receptors.
Original languageEnglish
Pages (from-to)4567-4575
Number of pages9
JournalJournal of Cell Science
Volume125
Issue number19
Early online date5 Jul 2012
DOIs
Publication statusPublished - 1 Oct 2012

Fingerprint

glycylphenylalanine
Exocytosis
Lysosomes
Monocytes
Adenosine Triphosphate
Apyrase
Ethylmaleimide
Cathepsin C
Dantrolene
Hexosaminidases
Ryanodine Receptor Calcium Release Channel
Thapsigargin
Adenosine Triphosphatases
Homeostasis

Cite this

Sivaramakrishnan, V., Bidula, S., Campwala, H., Katikaneni, D., & Fountain, S. (2012). Constitutive lysosome exocytosis releases ATP and engages P2Y receptors in human monocytes. Journal of Cell Science, 125(19), 4567-4575. https://doi.org/10.1242/jcs.107318

Constitutive lysosome exocytosis releases ATP and engages P2Y receptors in human monocytes. / Sivaramakrishnan, Venketesh; Bidula, Stefan; Campwala, Hinnah; Katikaneni, Divya; Fountain, Samuel.

In: Journal of Cell Science, Vol. 125, No. 19, 01.10.2012, p. 4567-4575.

Research output: Contribution to journalArticle

Sivaramakrishnan, V, Bidula, S, Campwala, H, Katikaneni, D & Fountain, S 2012, 'Constitutive lysosome exocytosis releases ATP and engages P2Y receptors in human monocytes', Journal of Cell Science, vol. 125, no. 19, pp. 4567-4575. https://doi.org/10.1242/jcs.107318
Sivaramakrishnan V, Bidula S, Campwala H, Katikaneni D, Fountain S. Constitutive lysosome exocytosis releases ATP and engages P2Y receptors in human monocytes. Journal of Cell Science. 2012 Oct 1;125(19):4567-4575. https://doi.org/10.1242/jcs.107318
Sivaramakrishnan, Venketesh ; Bidula, Stefan ; Campwala, Hinnah ; Katikaneni, Divya ; Fountain, Samuel. / Constitutive lysosome exocytosis releases ATP and engages P2Y receptors in human monocytes. In: Journal of Cell Science. 2012 ; Vol. 125, No. 19. pp. 4567-4575.
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