Dataset Information

Antagonistic regulation of apoptosis by polysulfides and thioredoxin via persulfidation of caspases

ABSTRACT: Hydrogen sulfide has been implicated in a large number of physiological processes including cell survival and death, encouraging research into its mechanisms of action and therapeutic potential. Recent studies suggest that the cellular effects of hydrogen sulfide are mediated in part by sulfane sulfur species including persulfides and polysulfides. In the present study, we investigated the apoptosis-modulating effects of polysulfides, in particular, in relation to the caspase cascade that mediates the intrinsic apoptotic pathway. Biochemical analyses revealed that organic or synthetic polysulfides strongly and rapidly inhibited the enzymatic activity of caspase-3, a major effector protease in apoptosis. Enzyme inhibition was attributed to persulfidation of the catalytic cysteine. In apoptotically stimulated HeLa cells, short-term exposure to polysulfides triggered the persulfidation and deactivation of cleaved caspae-3. These effects were antagonized by the thioredoxin/thioredoxin reductase system (Trx/TrxR). Indeed, Trx/TrxR restored the activity of polysulfide-inactivated caspase-3 in vitro, and inhibition of TrxR potentiated polysulfidemediated suppression of caspase-3 activity in situ. We further found that under conditions of low TrxR activity, early cell exposure to polysulfides lead to enhanced persulfidation of initiator caspase-9, resulting in decreased apoptosis. Beyond these observations, we show that the proenzymes, procaspase-3/-9, are basally persulfidated in resting (unstimulated) cells and become depersulfidated during their processing and activation. Inhibition of TrxR attenuated the depersulfidation and activation of caspase-9. Taken together, our results reveal that polysulfides target the caspase-9/3 cascade to suppress cancer cell apoptosis. The findings further suggest that Trx/TrxR-mediated depersulfidation may regulate caspase-dependent cell death.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Tamar Ziv

LAB HEAD: Moran Benhar

PROVIDER: PXD017144 | Pride | 2020-02-18

REPOSITORIES: Pride

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Opposing effects of polysulfides and thioredoxin on apoptosis through caspase persulfidation.

Braunstein Ilana I Engelman Rotem R Yitzhaki Ofer O Ziv Tamar T Galardon Erwan E Benhar Moran M

The Journal of biological chemistry 20200210 11

Hydrogen sulfide has been implicated in a large number of physiological processes including cell survival and death, encouraging research into its mechanisms of action and therapeutic potential. Results from recent studies suggest that the cellular effects of hydrogen sulfide are mediated in part by sulfane sulfur species, including persulfides and polysulfides. In the present study, we investigated the apoptosis-modulating effects of polysulfides, especially on the caspase cascade, which mediat ...[more]

PMID: 32041780

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Project description:Hydrogen sulfide is an important signaling molecule in plants that regulates essential biological processes through protein persulfidation. Although numerous persulfidated proteins were found to be involved in photorespiration, little was known about sulfide-mediated regulation of photorespiration. Label-free quantitative proteomic analysis has revealed a high impact on the protein persulfidation level when plants grown under non-photorespiratory conditions are transferred to air, with the 97 % of total identified proteins more persulfidated under suppressed photorespiration. A detailed study of the effect of sulfide on important aspects associated with photorespiratory growth conditions has provided insight into the role of sulfide in protecting plants grown under suppressed photorespiration. In these conditions, sulfide amends the metabolic imbalance of carbon/nitrogen and restores ATP levels to concentrations similar to those in air grown conditions. Sulfide also plays an essential role in balancing the significant high level of ROS measured in plants under non-photorespiratory conditions to reach a similar cellular redox state in air-grown plants, through the regulation of antioxidative defenses. Furthermore, sulfide regulates another important characteristic resulting from suppression of photorespiration, such as the stomata closure, to decrease the high guard cell ROS levels and inducing the stomata aperture. In this way, sulfide signals the movement of the CO2-dependent stomata to achieve a scenario similar to that of plants growing under normal air conditions, in the opposite direction of the already established ABA-dependent movement of the stomata. Therefore, our findings suggest that the high persulfidation level under suppressed photorespiration reveals an essential role of sulfide signaling under these conditions, and with respect to stomatal movement, the outcome of this signaling is dependent on the growth/stress condition under study.

Project description:Murine BV2 microglia cells were transfected either with siRNA negative control or siRNA against caspase-3 for 48h. Later on some the of the BV2 transfected cells were co-cultured with C6 glioma cells during 6h. We used the SA Biosciences Mouse Wound Healing PCR Array (PAMM-121Z) to quantitate gene expression of relevant genes related to the wound healing process Glioma cells recruit and exploit microglia, resident immune cells of the brain, for their proliferation and invasion capability. The underlying molecular mechanism used by glioma cells to transform microglia into a tumor-supporting phenotype remains elusive. Here, we report that glioma-induced microglia conversion is coupled to a reduction of basal microglial caspase-3 activity, increased S-nitrosylation of mitochondria-associated caspase-3 through inhibition of thioredoxin-2 activity, and demonstrate that caspase-3 inhibition regulates microglial tumor-supporting function. Further, we identified nitric oxide synthase-2 (NOS2) activity originating from the glioma cells as a driving stimulus in the control of microglial caspase-3 activity. Repression of glioma NOS2 expression in vivo led to reduction in both microglia recruitment and tumor expansion, whereas depletion of the microglial caspase-3 gene promoted tumor growth. This study provides evidence that the inhibition of Trx2-mediated denitrosylation of SNO-procaspase-3 is part of the microglial pro-tumoral activation pathway initiated by glioma cancer cells. qPCR gene expression profiling. Three independent experiments of siControl BV2 monoculture, siCaspase3 BV2 monoculture, siControl BV2 cocultured 6h with C6 glioma cells and siCaspase3 BV2 cocultured 6h with C6 glioma cells. Equal amount total RNA from each culture was used for the gene expression analysis. Please note that the raw data for three independent experiments (prior to averaging the data) is provided in the 'Raw_Data_File_with_the_Ct_values_for_3_indep_experiments.txt'.

			Action	DRS
	Seq56629_QE3-02.msf	Msf
	Seq56629_QE3.msf	Msf
	Seq56629_QE3.raw	Raw
	Seq56630_QE3-02.msf	Msf
	Seq56630_QE3.msf	Msf