Suberoylanilide hydroxamic acid upregulates reticulophagy receptor expression and promotes cell death in hepatocellular carcinoma cells

BACKGROUND Hepatocellular carcinoma(HCC)is a common clinical condition with a poor prognosis and few effective treatment options.Potent anticancer agents for treating HCC must be identified.Epigenetics plays an essential role in HCC tumorigenesis.Suberoylanilide hydroxamic acid(SAHA),the most common histone deacetylase inhibitor agent,triggers many forms of cell death in HCC.However,the underlying mechanism of action remains unclear.Family with sequence similarity 134 member B(FAM134B)-induced reticulophagy,a selective autophagic pathway,participates in the decision of cell fate and exhibits anticancer activity.This study focused on the relationship between FAM134B-induced reticulophagy and SAHA-mediated cell death.AIM To elucidate potential roles and underlying molecular mechanisms of reticulophagy in SAHA-induced HCC cell death.METHODS The viability,apoptosis,cell cycle,migration,and invasion of SAHA-treated Huh7 and MHCC97L cells were measured.Proteins related to the reticulophagy pathway,mitochondria-endoplasmic reticulum(ER)contact sites,intrinsic mitochondrial apoptosis,and histone acetylation were quantified using western blotting.ER and lysosome colocalization,and mitochondrial Ca^(2+)levels were characterized via confocal microscopy.The level of cell death was evaluated through Hoechst 33342 staining and propidium iodide colocalization.Chromatin immunoprecipitation was used to verify histone H4 lysine-16 acetylation in the FAM134B promoter region.RESULTS After SAHA treatment,the proliferation of Huh7 and MHCC97L cells was significantly inhibited,and the migration and invasion abilities were greatly blocked in vitro.This promoted apoptosis and caused G1 phase cells to increase in a concentration-dependent manner.Following treatment with SAHA,ER-phagy was activated,thereby triggering autophagy-mediated cell death of HCC cells in vitro.Western blotting and chromatin immunoprecipitation assays confirmed that SAHA regulated FAM134B expression by enhancing the histone H4 lysine-16 acetylation in the FAM134B promoter region.Further,SAHA disturbed the Ca^(2+)homeostasis and upregulated the level of autocrine motility factor receptor and proteins related to mitochondria-endoplasmic reticulum contact sites in HCC cells.Additionally,SAHA decreased the mitochondrial membrane potential levels,thereby accelerating the activation of the reticulophagy-mediated mitochondrial apoptosis pathway and promoting HCC cell death in vitro.CONCLUSION SAHA stimulates FAM134B-mediated ER-phagy to synergistically enhance the mitochondrial apoptotic pathway,thereby enhancing HCC cell death.

Roles of SET7/9 and LSD1 in the Pathogenesis of Arsenicinduced Hepatocyte Apoptosis

Background and Aims:Multiple regulatory mechanisms play an important role in arsenic-induced liver injury.To investigate whether histone H3 lysine 4(H3K4)methyltransferase(SET7/9)and histone H3K4 demethyltransferase(LSD1/KDM1A)can regulate endoplasmic reticulum stress(ERS)-related apoptosis by modulating the changes of H3K4 methylations in liver cells treated with arsenic.Methods:Apoptosis,proliferation and cell cycles were quantified by flow cytometry and real-time cell analyzer.The expression of ERS-and epigenetic-related proteins was detected by Western blot analysis.The antisense SET7/9 expression vector and the overexpressed LSD1 plasmid were used for transient transfection of LO_(2) cells.The effects of NaAsO_(2) on the methylation of H3 in the promoter regions of 78 kDa glucose-regulated protein,activating transcription factor 4 and C/EBP-homologous protein were evaluated by chromatin immunoprecipitation assay.Results:The protein expression of LSD1(1.25±0.08 vs.1.77±0.08,p=0.02)was markedly decreased by treatment with 100μM NaAsO_(2),whereas the SET7/9(0.68±0.05 vs.1.10±0.13,p=0.002)expression level was notably increased,which resulted in increased H3K4me1/2(0.93±0.64,1.19±0.22 vs.0.71±0.13,0.84±0.13,p=0.03 and p=0.003).After silencing SET7/9 and overexpressing LSD1 by transfection,apoptosis rate(in percentage:3.26±0.34 vs.7.04±0.42,4.80±0.32 vs.7.52±0.38,p=0.004 and p=0.02)was significantly decreased and proliferation rate was notably increased,which is reversed after inhibiting LSD1(in percentage:9.31±0.40 vs.7.52±0.38,p=0.03).Furthermore,the methylation levels of H3 in the promoter regions of GRP78(20.80±2.40 vs.11.75±2.47,20.46±2.23 vs.14.37±0.91,p=0.03 and p=0.01)and CHOP(48.67±4.04 vs.16.67±7.02,59.33±4.51 vs.20.67±3.06,p=0.004 and p=0.001)were significantly increased in LO_(2) cells exposed to 100μM NaAsO_(2) for 24 h.Conclusions:Histone methyltransferase SET7/9 and histone demethyltransferase LSD1 jointly regulate the changes of H3K4me1/me2 levels in arsenic-induced apoptosis.NaAsO_(2) induces apoptosis in LO_(2) cells by activating the ERS-mediated apoptotic signaling pathway,at least partially by enhancing the methylation of H3 on the promoter regions of ERS-associated genes,including GRP78 and CHOP.

Calpain-2 activity promotes aberrant endoplasmic reticulum stress-related apoptosis in hepatocytes

BACKGROUND Calpain-2 is a Ca^2+-dependent cysteine protease,and high calpain-2 activity can enhance apoptosis mediated by multiple triggers.AIM To investigate whether calpain-2 can modulate aberrant endoplasmic reticulum(ER)stress-related apoptosis in rat hepatocyte BRL-3A cells.METHODS BRL-3A cells were treated with varying doses of dithiothreitol(DTT),and their viability and apoptosis were quantified by 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2-H-tetrazolium bromide and flow cytometry.The expression of ER stress-and apoptosis-related proteins was detected by Western blot analysis.The protease activity of calpain-2 was determined using a fluorescent substrate,Nsuccinyl-Leu-Leu-Val-Tyr-AMC.Intracellular Ca^2+content,and ER and calpain-2 co-localization were characterized by fluorescent microscopy.The impact of calpain-2 silencing by specific small interfering RNA on caspase-12 activation and apoptosis of BRL-3A cells was quantified.RESULTS DTT exhibited dose-dependent cytotoxicity against BRL-3A cells and treatment with 2 mmol/L DTT triggered BRL-3A cell apoptosis.DTT treatment significantly upregulated 78 kDa glucose-regulated protein,activating transcription factor 4,C/EBP-homologous protein expression by>2-fold,and enhanced PRKR-like ER kinase phosphorylation,caspase-12 and caspase-3 cleavage in BRL-3A cells in a trend of time-dependence.DTT treatment also significantly increased intracellular Ca^2+content,calpain-2 expression,and activity by>2-fold in BRL-3A cells.Furthermore,immunofluorescence revealed that DTT treatment promoted the ER accumulation of calpain-2.Moreover,calpain-2 silencing to decrease calpain-2 expression by 85%significantly mitigated DTT-enhanced calpain-2 expression,caspase-12 cleavage,and apoptosis in BRL-3A cells.CONCLUSION The data indicated that Ca^2+-dependent calpain-2 activity promoted the aberrant ER stress-related apoptosis of rat hepatocytes by activating caspase-12 in the ER.

Family with sequence similarity 134 member B-mediated reticulophagy ameliorates hepatocyte apoptosis induced by dithiothreitol

BACKGROUND Endoplasmic reticulum(ER)stress-related hepatocyte apoptosis is responsible for multiple hepatic diseases.Previous studies have revealed that endoplasmic reticulophagy(ER-phagy)promotes the selective clearance of damaged ER fragments during ER stress,playing a crucial role in maintaining ER homeostasis and inhibiting apoptosis.Family with sequence similarity 134 member B(FAM134B)is a receptor involved in ER-phagy that can form a complex with calnexin(CNX)and microtubule-associated protein 1 light chain 3(LC3).The complex can mediate the selective isolation of ER fragments to attenuate hepatocyte apoptosis.However,the precise regulatory mechanisms remain unclear.AIM To elucidate the effect of FAM134B-mediated ER-phagy on ER stress-induced apoptosis in buffalo rat liver 3A(BRL-3A)rat hepatocytes and the potential regulatory mechanisms.METHODS ER stress-related hepatocyte apoptosis was induced using dithiothreitol(DTT).Proteins related to ER stress and autophagy were measured with western blotting.Protein complex interactions with FAM134B were isolated by co-immunoprecipitation.ER-phagy was evaluated in immunofluorescence experiments.Cell cycle distribution and apoptosis were measured by flow cytometry.Mitochondrial Ca^(2+) levels were evaluated by the co-localization of intracellular Ca^(2+)-tracker and Mitotracker.The small interfering RNA against FAM134B was used to knockdown FAM134B in BRL-3A cells.RESULTS ER stress-related and autophagy-related proteins in BRL-3A cells were elevated by both short and long-term DTT treatment.Furthermore,co-immunoprecipitation confirmed an interaction between FAM134B,CNX,FAM134B,and LC3 in BRL-3A cells.Immunofluorescence assays revealed that autolysosomes significantly decreased following short-term DTT treatment,but increased after long-term treatment.Mitochondrial Ca2+levels and apoptotic rates were dramatically elevated,and more cells were arrested in the G1 stage after short-term DTT treatment;however,these decreased 48 h later.Moreover,FAM134B downregulation accelerated mitochondrial apoptotic pathway activation and aggravated hepatocyte apoptosis under ER stress.CONCLUSION FAM134B-mediated ER-phagy attenuates hepatocyte apoptosis by suppressing the mitochondrial apoptotic pathway.Our findings provide new evidence highlighting the importance of FAM134Bmediated ER-phagy in attenuating hepatocyte apoptosis.

LSD1调控颗粒细胞自噬并抑制Wt1参与FSH调节的有腔卵泡形成

In a growing follicle,the survival and maturation of the oocyte largely depend on support from somatic cells to facilitate FSH-induced mutual signaling and chemical communication.Although apoptosis and autophagy in somatic cells are involved in the process of FSH-induced follicular development,the underlying mechanisms require substantial study.According to our study,along with FSH-induced antral follicles(AFs)formation,both lysine-specific demethylase 1(LSD1)protein levels and autophagy increased simultaneously in granulosa cells(GCs)in a time-dependent manner,we therefore evaluated the importance of LSD upon facilitating the formation of AFs correlated to autophagy in GCs.Conditional knockout of Lsdl in GCs resulted in significantly decreased AF number and subfertility in females,accompanied by marked suppression of the autophagy in GCs.On the one hand,depletion of Lsd1 resulted in accumulation of Wilms tumor 1 homolog(WT1),at both the protein and mRNA levels.WT1 prevented the expression of FSH receptor(Fshr)in GCs and thus reduced the responsiveness of the secondary follicles to FSH induction.On the other hand,depletion of LSD1 resulted in suppressed level of autophagy by upregulation of ATG16L2 in GCs.We finally approved that LSD1 contributed to these sequential activities in GCs through its H3K4me2 demethylase activity.Therefore,the importance of LSD1 in GCs is attributable to its roles in both accelerating autophagy and suppressing WT1 expression to ensure the responsiveness of GCs to FSH during AFs formation.