Chalcone suppresses tumor growth through NOX4-IRE1α sulfonation-RIDD-miR-23b axis

Reactive Oxygen Species: Not Omnipresent but Important in Many Locations

“…Often probes are used that show neither a specificity for a ROS subspecies nor a defined cellular compartment, which leads to the frequently used terms “intracellular ROS” or “total cellular ROS,” which implicate that ROS once produced are equally distributed in the cell. Common examples for diffusible ROS probes are luminol ( Caldefie-Chezet et al, 2002 ; Pavelkova and Kubala, 2004 ), 2′,7′-dichlordihydrofluorescein-diacetat (H2DCF-DA) ( Ushijima et al, 1997 ; Hempel et al, 1999 ; Kim and Xue, 2020 ; Kim et al, 2021 ; Wang et al, 2021a ) or dihydroethidium (DHE) ( Gatliff et al, 2017 ; Wang and Zou, 2018 ; Zeller et al, 2021 ), which are regarded as compartment-specific but in fact they are not ( Lundqvist and Dahlgren, 1996 ; Ushijima et al, 1997 ; Hempel et al, 1999 ; Wang and Zou, 2018 ). There are compartment-specific derivates available for these ROS probes, namely Isoluminol ( Lundqvist and Dahlgren, 1996 ; Dahlgren and Karlsson, 1999 ; Caldefie-Chezet et al, 2002 ; Gluschko et al, 2018 ; Herb et al, 2019b ; Wolf et al, 2020 ), 5-(and −6)-carboxy-2′,7′-dihydrochlorofluorescein-diacetat (5/6-Carboxy-DCF) ( Hempel et al, 1999 ; Mak et al, 2017 ; Herb et al, 2019b ; Wolf et al, 2020 ) and MitoSOX Red (MitoSOX) ( Robinson et al, 2006 ; Mukhopadhyay et al, 2007 ) as alternatives, whose combined usage gives a much more confluent picture of the cellular ROS production.…”

“…For Nox enzymes, as one of the most prominent ROS sources in many cell types, the well-validated general Nox inhibitors VAS2870 ( Leusen et al, 1995 ; ten Freyhaus et al, 2006 ; Wind et al, 2010 ; Altenhofer et al, 2012 , 2015 ) or GKT 137831 ( Laleu et al, 2010 ; Sedeek et al, 2010 ; Gaggini et al, 2011 ; Aoyama et al, 2012 ; Strengert et al, 2014 ; Kim et al, 2021 ) can be used. Both inhibitors show no intrinsic antioxidant activity and do not inhibit other flavoproteins ( Wind et al, 2010 ; Altenhofer et al, 2012 ; Teixeira et al, 2017 ).…”

“…This further places the model of ROS molecules, which “flood” the whole cell from a single location of ROS production in rather unrealistic light. Nevertheless, the model of ROS as “flooding” the cell is still popular in the scientific community, often referred to as “total cellular ROS levels” ( Wang et al, 2013 , 2019 ; Dinakar et al, 2016 ; Kim and Xue, 2020 ; Loth et al, 2020 ; Thorne et al, 2021 ), “intracellular ROS levels” ( Tepel et al, 2000 ; Bensaad et al, 2009 ; Choi et al, 2011 ; Lee et al, 2017 ; Wang et al, 2019 , 2021a ; Wei et al, 2019 ; Zaidieh et al, 2019 ; Zhang W. et al, 2019 ; Mendiola et al, 2020 ; Winitchaikul et al, 2021 ; Zhong et al, 2021 ) or simply “ROS levels” ( Chen et al, 2012 , 2021 ; Wei et al, 2019 ; Agarwal and Ganesh, 2020 ; Kim et al, 2021 ; Knight et al, 2021 ; Zeller et al, 2021 ) in many studies, mainly because of the usage of diffusible ROS probes, which suggest free diffusion of ROS through the cell without regard of the location of ROS production. Mutations, e.g., in cancer cells ( Schumacker, 2006 ; Liou and Storz, 2010 ; Reczek and Chandel, 2017 ; Zaidieh et al, 2019 ; Perillo et al, 2020 ), pathogenic invasion ( West et al, 2011a ; Abuaita et al, 2018 ; Gluschko et al, 2018 ; Roca et al, 2019 ) or metabolic disbalance ( Li et al, 2016 ; Mak et al, 2017 ; Peng et al, 2021 ) are prominent examples, in which the ROS production of the cell can enter an uncontrolled stage and quickly overcome the antioxidative defense system leading to rapidly increased ROS levels in nearly every compartment of the cell with often detrimental consequences.…”

TMBIM6 regulates redox-associated posttranslational modifications of IRE1α and ER stress response failure in aging mice and humans

“…SNO-IRE1α promotes defective IRE1α RNase activity, while SO 3 H-IRE1α increases RIDD without affecting XBP1 splicing [ 21 , 32 ]. Therefore, we performed an in vitro cleavage assay [ 21 ] to detect the effect of SNO and SO 3 H on XBP1 and RIDD processing using a fluorescence resonance energy transfer (FRET)–quenched XBP1 and SPARC (secreted protein acidic and rich in cysteine) RNA minisubstrate, and a purified human IRE1α (amino acids 465–977, IRE1c).…”

“…Cysteine residues 931 (C931) and 951 (C951) of IRE1α peptides located in the RNase domain are identified for the relevant S-nitrosylation that impairs IRE1α RNase enzyme activity, eventually attenuating XBP1 splicing [ 21 , 50 ]. Recently, we have discovered that IRE1α is S-sulfonated at C715 and C762, which is mediated by a high level of ROS and can trigger ER stress-induced apoptosis [ 32 ]. In contrast, increased iNOS-induced metaflammation is associated with impaired XBP1 processing in obesity [ 21 ], which is consistent with our findings in the age-associated steatosis model ( Fig.…”