Critical role of gap junction communication, calcium and nitric oxide signaling in bystander responses to focal photodynamic injury

Keywords: calcium pumps, mathematical modeling, pulsatile insulin secretion, photosensitizer, ROS/RNS Abbreviations: AlClPc, Aluminum Phthalocyanine Chloride; CICR, calcium-induced calcium release; CuFL, selective turn-on fluorescent NO reporter formed by a Cu(II) complex of a fluorescein modified with an appended metal-chelating ligand (FL); ER, endoplasmic reticulum; IP 3 R, inositol triphospate receptor; MitoSOX, mitochondrial superoxide indicator; NO, nitric oxide; PMCA, plasma membrane Ca 2C ATPase; RNS, reactive nitrogen species; ROS, reactive oxygen species; RyR, ryanodine receptor; SERCA, Sarcoplasmic/endoplasmic reticulum Ca 2C ATPase; TEA, tetraethylammonium; Tg, thapsigargin.Disturbances in pulsatile insulin secretion and Ca 2C oscillations in pancreatic b-cells are early markers of diabetes, but the underlying mechanisms are still incompletely understood. Reactive oxygen/nitrogen species (ROS/RNS) are implicated in reduced b-cell function, and ROS/RNS target several Ca 2C pumps and channels. Thus, we hypothesized that ROS/RNS could disturb Ca 2C oscillations and downstream insulin pulsatility. We show that ROS/RNS production by photoactivation of aluminum phthalocyanine chloride (AlClPc) abolish or accelerate Ca 2C oscillations in the MIN6 b-cell line, depending on the amount of ROS/RNS. Application of the sarcoplasmic/endoplasmic reticulum Ca 2C ATPase (SERCA) inhibitor thapsigargin modifies the Ca 2C response to high concentrations of ROS/RNS. Further, thapsigargin produces effects that resemble those elicited by moderate ROS/RNS production. These results indicate that ROS/RNS interfere with endoplasmic reticulum Ca 2C handling. This idea is supported by theoretical studies using a mathematical model of Ca 2C handling adapted to MIN6 cells. Our results suggest a putative link between ROS/RNS and disturbed pulsatile insulin secretion. IntroductionInsulin is secreted from the pancreatic b-cells in distinct pulses 1,2 and disturbed pulsatile insulin release has been suggested to be an early marker of diabetes. 3 These bursts of insulin are driven by underlying oscillations in electrical activity and cytosolic Ca 2C levels, which periodically trigger Ca 2C -regulated exocytosis. 4 Importantly, secretory pulses are more effective than constant insulin levels in lowering plasma glucose levels. 3,5,6 In particular, hepatic signaling is highly sensitive to whether insulin is released in pulses, 7 leading to the suggestion that insulin resistance in the liver is secondary to disturbed pulsatile insulin release. 8 Thus, a deeper understanding of oscillatory b-cell activity and its disturbance has clinical relevance.Disturbed insulin secretion and diabetes have been associated with b-cell damage caused by reactive oxygen species (ROS). 9 However, ROS have also been shown to exert a stimulating short-term effect on insulin release. 10 Hence, ROS may act as a double-edged sword: moderate and short-term elevations play a positive signaling role augmenting insulin secretion, but prolonged exposure to elevated ROS...

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“…S1). In addition, AlClPc photoactivation increased NO levels, 21 as reported by the selective fluorescent probe CuFL 21 ( Fig. 2B; see also 19 ).…”

Section: Resultssupporting

confidence: 72%

“…[19][20][21] Here we show that ROS/ RNS production by AlClPc photoactivation accelerates or abolishes Ca 2C oscillations in the widely used insulin-secreting MIN6 b-cell line. To guide the interpretation of our results, we used a mathematical model of Ca 2C handling adapted to MIN6 cells.…”

Section: Introductionmentioning

confidence: 95%

Reactive oxygen and nitrogen species disturb Ca²⁺oscillations in insulin-secreting MIN6 β-cells

Antonucci

Tagliavini

Pedersen

2015

Islets

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“…Although encouraging, T‐cell sparing was not ubiquitous, suggesting imperfect selectivity and remaining off‐target cytotoxicity. This may conceivably be due in part to bystander effects that propagate cell death signaling pathways to neighboring cells or cytotoxic cytokines ( e.g . interferon‐ γ and tumor necrosis factor‐ α ) released by dying T cells after high‐dose PDT.…”

Section: Resultsmentioning

confidence: 99%

Cancer Cell‐targeted and Activatable Photoimmunotherapy Spares T Cells in a 3D Coculture Model

Kercher

Nath

Rizvi

et al. 2019

Photochem & Photobiology

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Photodynamic therapy (PDT) is an established therapeutic modality that uses nonionizing near‐infrared light to activate photocytotoxicity of endogenous or exogenous photosensitizers (PSs). An ongoing avenue of cancer research involves leveraging PDT to stimulate antitumor immune responses; however, these effects appear to be best elicited in low‐dose regimens that do not provide significant tumor reduction using conventional, nonspecific PSs. The loss of immune enhancement at higher PDT doses may arise in part from indiscriminate damage to local immune cell populations, including tumor‐infiltrating T cells. We previously introduced “tumor‐targeted, activatable photoimmunotherapy” (taPIT) using molecular‐targeted and cell‐activatable antibody–PS conjugates to realize precision tumor photodamage with microscale fidelity. Here, we investigate the immune cell sparing effect provided by taPIT in a 3D model of the tumor immune microenvironment. We report that high‐dose taPIT spares 25% of the local immune cell population, five times more than the conventional PDT regimen, in a 3D coculture model incorporating epithelial ovarian cancer cells and T cells. These findings suggest that the enhanced selectivity of taPIT may be utilized to achieve local tumor reduction with sparing of intratumor effector immune cells that would otherwise be lost if treated with conventional PDT.

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“…7a, b). NO may be part of this triad, as it is activated by Ca 2+ -calmodulin signaling, facilitates intercellular Ca 2+ signal communication 57 , contributes to bystander Ca 2+ -signal signaling in photodynamic therapy 67 , and may induce DSBs via peroxynitrite (ONOO − ) formed by its reaction with ROS 39 . Accordingly, C-PTIO-based NO scavenging inhibited radiation-induced ATP release (Fig.…”

Section: +mentioning

confidence: 99%

Cx43 channels and signaling via IP3/Ca2+, ATP, and ROS/NO propagate radiation-induced DNA damage to non-irradiated brain microvascular endothelial cells

et al. 2020

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Radiotherapeutic treatment consists of targeted application of radiation beams to a tumor but exposure of surrounding healthy tissue is inevitable. In the brain, ionizing radiation induces breakdown of the blood-brain barrier by effects on brain microvascular endothelial cells. Damage from directly irradiated cells can be transferred to surrounding non-exposed bystander cells, known as the radiation-induced bystander effect. We investigated involvement of connexin channels and paracrine signaling in radiation-induced bystander DNA damage in brain microvascular endothelial cells exposed to focused X-rays. Irradiation caused DNA damage in the directly exposed area, which propagated over several millimeters in the bystander area. DNA damage was significantly reduced by the connexin channel-targeting peptide Gap26 and the Cx43 hemichannel blocker TAT-Gap19. ATP release, dye uptake, and patch clamp experiments showed that hemichannels opened within 5 min post irradiation in both irradiated and bystander areas. Bystander signaling involved cellular Ca 2+ dynamics and IP 3 , ATP, ROS, and NO signaling, with Ca 2+ , IP 3 , and ROS as crucial propagators of DNA damage. We conclude that bystander effects are communicated by a concerted cascade involving connexin channels, and IP 3 /Ca 2+ , ATP, ROS, and NO as major contributors of regenerative signal expansion.

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Critical role of gap junction communication, calcium and nitric oxide signaling in bystander responses to focal photodynamic injury

Cited by 32 publications

References 68 publications

Reactive oxygen and nitrogen species disturb Ca²⁺oscillations in insulin-secreting MIN6 β-cells

Reactive oxygen and nitrogen species disturb Ca²⁺oscillations in insulin-secreting MIN6 β-cells

Cancer Cell‐targeted and Activatable Photoimmunotherapy Spares T Cells in a 3D Coculture Model

Cx43 channels and signaling via IP3/Ca2+, ATP, and ROS/NO propagate radiation-induced DNA damage to non-irradiated brain microvascular endothelial cells

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Critical role of gap junction communication, calcium and nitric oxide signaling in bystander responses to focal photodynamic injury

Cited by 32 publications

References 68 publications

Reactive oxygen and nitrogen species disturb Ca2+oscillations in insulin-secreting MIN6 β-cells

Reactive oxygen and nitrogen species disturb Ca2+oscillations in insulin-secreting MIN6 β-cells

Cancer Cell‐targeted and Activatable Photoimmunotherapy Spares T Cells in a 3D Coculture Model

Cx43 channels and signaling via IP3/Ca2+, ATP, and ROS/NO propagate radiation-induced DNA damage to non-irradiated brain microvascular endothelial cells

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Reactive oxygen and nitrogen species disturb Ca²⁺oscillations in insulin-secreting MIN6 β-cells

Reactive oxygen and nitrogen species disturb Ca²⁺oscillations in insulin-secreting MIN6 β-cells