The unfolded protein response is a cellular pathway activated to maintain proteostasis and prevent cell death when the endoplasmic reticulum is overwhelmed by unfolded proteins.However,if the unfolded protein response...The unfolded protein response is a cellular pathway activated to maintain proteostasis and prevent cell death when the endoplasmic reticulum is overwhelmed by unfolded proteins.However,if the unfolded protein response fails to restore endoplasmic reticulum homeostasis,it can trigger proinflammatory and pro-death signals,which are implicated in various malignancies and are currently being investigated for their role in retinal degenerative diseases.This paper reviews the role of the unfolded protein responsein addressing endoplasmic reticulumstress in retinal degenerative diseases.The accumulation of ubiquitylated misfolded proteins can lead to rapid destabilization of the proteome and cellular demise.Targeting endoplasmic reticulum stress to alleviate retinal pathologies involves multiple strategies,including the use of chemical chaperones such as 4-phenylbutyric acid and tauroursodeoxycholic acid,which enhance protein folding and reduce endoplasmic reticulum stress.Small molecule modulators that influence endoplasmic reticulum stress sensors,including those that increase the expression of the endoplasmic reticulum stress regulator X-box binding protein 1,are also potential therapeutic agents.Additionally,inhibitors of the RNAse activity of inositol-requiring transmembrane kinase/endoribonuclease 1,a key endoplasmic reticulum stress sensor,represent another class of drugs that could prevent the formation of toxic aggregates.The activation of nuclear receptors,such as PPAR and FXR,may also help mitigate ER stress.Furthermore,enhancing proteolysis through the induction of autophagy or the inhibition of deubiquitinating enzymes can assist in clearing misfolded proteins.Combination treatments that involve endoplasmicreticulum-stress-targeting drugs and gene therapies are also being explored.Despite these potential therapeutic strategies,significant challenges remain in targeting endoplasmic reticulum stress for the treatment of retinal degeneration,and further research is essential to elucidate the mechanisms underlying human retinal diseases and to develop effective,well-tolerated drugs.The use of existing drugs that target inositol-requiring transmembrane kinase/endoribonuclease 1 and X-box binding protein 1 has been associated with adverse side effects,which have hindered their clinical translation.Moreover,signaling pathways downstream of endoplasmic reticulum stress sensors can contribute to therapy resistance.Addressing these limitations is crucial for developing drugs that can be effectively used in treating retinal dystrophies.In conclusion,while the unfolded protein response is a promising therapeutic target in retinal degenerative diseases,additional research and development efforts are imperative to overcome the current limitations and improve patient outcomes.展开更多
The mechanism regulating proteasomal activity under proteotoxic stress conditions remains unclear.Here,we showed that arsenite-induced proteotoxic stress resulted in upregulation of Arabidopsis homologous PUB22 and PU...The mechanism regulating proteasomal activity under proteotoxic stress conditions remains unclear.Here,we showed that arsenite-induced proteotoxic stress resulted in upregulation of Arabidopsis homologous PUB22 and PUB23 U-boxE3 ubiquitin ligases and that pub22 pub23 double mutants displayed arsenite-insensitive seed germination and root growth phenotypes.PUB22/PUB23 downregulated 26 S proteasome activity by promoting the dissociation of the 19 S regulatory particle from the holo-proteasome complex,resulting in intracellular accumulation of UbG76 VGFP,an artificial substrate of the proteasome complex,and insoluble poly-ubiquitinated proteins.These results suggest that PUB22/PUB23 play a critical role in arsenite-induced proteotoxic stress response via negative regulation of 26 S proteasome integrity.展开更多
Drought stress has detrimental effects on plants.Although the abscisic acid(ABA)-mediated drought response is well established,defensive mechanisms to cope with dehydration-induced proteotoxicity have been rarely stud...Drought stress has detrimental effects on plants.Although the abscisic acid(ABA)-mediated drought response is well established,defensive mechanisms to cope with dehydration-induced proteotoxicity have been rarely studied.DRR1 was identified as an Arabidopsis drought-induced gene encoding an ER-localized RING-type E3 Ub ligase.Suppression of DRR1 markedly reduced tolerance to drought and proteotoxic stress without altering ABA-mediated germination and stomatal movement.Proteotoxicityand dehydration-induced insoluble ubiquitinated protein accumulation was more obvious in DRR1 loss-of-function plants than in wild-type plants.These results suggest that DRR1 is involved in an ABA-independent drought stress response possibly through the mitigation of dehydration-induced proteotoxic stress.展开更多
基金supported by the Natural Science Foundation of Shaanxi Province(Key Program),No.2021JZ-60(to HZ)。
文摘The unfolded protein response is a cellular pathway activated to maintain proteostasis and prevent cell death when the endoplasmic reticulum is overwhelmed by unfolded proteins.However,if the unfolded protein response fails to restore endoplasmic reticulum homeostasis,it can trigger proinflammatory and pro-death signals,which are implicated in various malignancies and are currently being investigated for their role in retinal degenerative diseases.This paper reviews the role of the unfolded protein responsein addressing endoplasmic reticulumstress in retinal degenerative diseases.The accumulation of ubiquitylated misfolded proteins can lead to rapid destabilization of the proteome and cellular demise.Targeting endoplasmic reticulum stress to alleviate retinal pathologies involves multiple strategies,including the use of chemical chaperones such as 4-phenylbutyric acid and tauroursodeoxycholic acid,which enhance protein folding and reduce endoplasmic reticulum stress.Small molecule modulators that influence endoplasmic reticulum stress sensors,including those that increase the expression of the endoplasmic reticulum stress regulator X-box binding protein 1,are also potential therapeutic agents.Additionally,inhibitors of the RNAse activity of inositol-requiring transmembrane kinase/endoribonuclease 1,a key endoplasmic reticulum stress sensor,represent another class of drugs that could prevent the formation of toxic aggregates.The activation of nuclear receptors,such as PPAR and FXR,may also help mitigate ER stress.Furthermore,enhancing proteolysis through the induction of autophagy or the inhibition of deubiquitinating enzymes can assist in clearing misfolded proteins.Combination treatments that involve endoplasmicreticulum-stress-targeting drugs and gene therapies are also being explored.Despite these potential therapeutic strategies,significant challenges remain in targeting endoplasmic reticulum stress for the treatment of retinal degeneration,and further research is essential to elucidate the mechanisms underlying human retinal diseases and to develop effective,well-tolerated drugs.The use of existing drugs that target inositol-requiring transmembrane kinase/endoribonuclease 1 and X-box binding protein 1 has been associated with adverse side effects,which have hindered their clinical translation.Moreover,signaling pathways downstream of endoplasmic reticulum stress sensors can contribute to therapy resistance.Addressing these limitations is crucial for developing drugs that can be effectively used in treating retinal dystrophies.In conclusion,while the unfolded protein response is a promising therapeutic target in retinal degenerative diseases,additional research and development efforts are imperative to overcome the current limitations and improve patient outcomes.
基金supported by grants from the National Research Foundation(Mid-Career Researcher Program Project No.2017R1A2B2006750 and Basic Science Research Program Project No.2018R1A6A1A03025607),Republic of Korea,to Woo T.Kim。
文摘The mechanism regulating proteasomal activity under proteotoxic stress conditions remains unclear.Here,we showed that arsenite-induced proteotoxic stress resulted in upregulation of Arabidopsis homologous PUB22 and PUB23 U-boxE3 ubiquitin ligases and that pub22 pub23 double mutants displayed arsenite-insensitive seed germination and root growth phenotypes.PUB22/PUB23 downregulated 26 S proteasome activity by promoting the dissociation of the 19 S regulatory particle from the holo-proteasome complex,resulting in intracellular accumulation of UbG76 VGFP,an artificial substrate of the proteasome complex,and insoluble poly-ubiquitinated proteins.These results suggest that PUB22/PUB23 play a critical role in arsenite-induced proteotoxic stress response via negative regulation of 26 S proteasome integrity.
基金supported by grants from the National Research Foundation(Mid-Career Researcher Program 2020R1A2B5B02001590 and Basic Science Research Program 2018R1A6A1A03025607,Republic of Korea)a Hyundai Motor Chung Mong-Koo Foundation Scholarship。
文摘Drought stress has detrimental effects on plants.Although the abscisic acid(ABA)-mediated drought response is well established,defensive mechanisms to cope with dehydration-induced proteotoxicity have been rarely studied.DRR1 was identified as an Arabidopsis drought-induced gene encoding an ER-localized RING-type E3 Ub ligase.Suppression of DRR1 markedly reduced tolerance to drought and proteotoxic stress without altering ABA-mediated germination and stomatal movement.Proteotoxicityand dehydration-induced insoluble ubiquitinated protein accumulation was more obvious in DRR1 loss-of-function plants than in wild-type plants.These results suggest that DRR1 is involved in an ABA-independent drought stress response possibly through the mitigation of dehydration-induced proteotoxic stress.
