P2X7R large pore is partially blocked by pore forming proteins antagonists in astrocytes

Abstract

The ATP-gated P2X7R (P2X7R) is a channel, which is involved in events, such as inflammation, cell death, and pain. The most intriguing event concerning P2X7R functions is the phenomenon of pore dilation. Once P2X7R is activated, the permeability of the plasma membrane becomes higher, leading to the permeation of 1000 Da-weight solutes. The mechanisms involved in this process remain unclear. Nevertheless, this event is not exclusively through P2X7R, as other proteins may form large pores in the plasma membrane. Recent evidence concerning pore formation reveals putative P2X7R and other pores-associated protein complexes, revealing cross-interactive pharmacological and biophysical issues. In this work, we showed results that corroborated with cross-interactive aspects with P2X7R and pores in astrocytes. These cells expressed most of the pores, including P2X7R. We discovered that different pore types open with peculiar characteristics, as both anionic and cationic charged solutes permeate the plasma membrane, following P2X7R activation. Moreover, we showed that both synergic and additive relationships are found within P2X7, cationic, and anionic large pores. Therefore, our data suggest that other protein-related pores are assembled following the formation of P2X7R pore.

P2X7 receptor‐targeted regulation by tetrahydroxystilbene glucoside in alcoholic hepatosteatosis: A new strategy towards macrophage–hepatocyte crosstalk

“…The IC 50 of 2354glu for [Ca 2+ ] i was 148 μM. ATP is known to elicit membrane pore dilatation by activating P2X7 receptors followed by cytolysis to trigger IL‐1β maturation (Faria, Reis, Ferreira, Cezar‐de‐Mello, & Moraes, ; Takenouchi et al, ; Wewers, ). Thus, we examined whether 2354glu prevented P2X7 receptor‐mediated pore formation in THP‐1 macrophages using PI uptake.…”

Glutathione-Induced Calcium Shifts in Chick Retinal Glial Cells

“…Avian Müller cells in culture express P2X7 receptors [ 28 ] and ATP is known to permeabilize mice cortical astrocytes [ 22 ] through a phenomenon described as pore dilation. Propidium iodide (PI, MW 668), is a molecule commonly used to measure cell permeabilization Therefore, we asked if addition of ATP or GSH to avian Müller cells in culture could induce PI uptake in a P2X7 receptor dependent manner.…”

“…For positive control of TUNEL, cells were treated with the inhibitor of the endoplasmic reticulum calcium ATPase thapsigargin. Previously, we described that thapsigargin induces apoptosis of photoreceptors in rat retinal tissue [ 22 ]. Here, we show that treatment with 30nM thapsigargin, for 24 hours, dramatically increases TUNEL positive cells ( Fig 8C ) in chicken retinal cell culture.…”

“…Avian Müller cells permeabilization was visualized and quantified by the differential uptake of 500 ng/mL propidium iodide (PI) essentially as described before for cultured mice astrocytes [ 22 ]. Müller glia cells were plated in a 96-well plate (Corning, SP, Brazil) and incubated at 37°C with ATP 1mM, GSH 5mM or GSH in the presence of P2X7 receptor antagonists or BAPTA-AM, which were added 10 min before.…”

Pore forming channels as a drug delivery system for photodynamic therapy in cancer associated with nanoscintillators

“…When open, they allow for the passage of molecules of up to 1,000 Da without necessarily leading to cell death. Among pore-forming proteins, pannexin-1 [ 54 ], connexin hemichannels [ 55 ], TRPV1-4 subtypes and TRPA1 [ 56 ], calcium homeostasis modulator 1 (CALHM1) [ 57 ], Maxi anion [ 58 ], plasma membrane VDAC [ 59 ] and ATP-gated subtypes P2×2 [ 60 – 62 ], P2×4 [ 63 – 65 ] and, especially, P2×7 receptors [ 66 – 68 ] are noteworthy (Figure 2 ). One possibility would be to study the involvement of the P2×7 associated-pore as an MB uptake route in the cytoplasm of neoplastic cells, and, in this regard, we have recently demonstrated that P2×7 can function as a drug delivery system in the J774 tumor cell line [ 69 ].…”