Iron accumulation in senescent cells is coupled with impaired ferritinophagy and inhibition of ferroptosis

In the paper

“Western blot analyses revealed that senescent MEFs (MEF IR) had significantly elevated levels of transferrin receptor 1 (TfR1), the principle protein responsible for the cellular uptake of iron via transferrin (Fe3+-transferrin) (Fig. 3A).”

• Also stated in: § Altered iron homeostatic mechanisms drive senescent cells to acquire profound levels of intracellular iron · plain

  “The divalent metal transporter 1 (DMT1) protein, which is involved in transport of iron (Fe2+) from endosomes to cytoplasm, did not significantly change (Fig. 3A).”

• Also stated in: § Altered iron homeostatic mechanisms drive senescent cells to acquire profound levels of intracellular iron · plain

  “Ferroportin was also increased in senescent cells (Fig. 3A) and can function to efflux iron from the cell under certain conditions.”

In the paper

“Senescent MEFs (MEFs IR) had significantly lower levels of both IRP1 and its regulator the iron-sulfur cluster assembly enzyme (ISCU) (Fig. 3C), which is required for iron-sulfur cluster biogenesis [48], [49], [50].”

• Also stated in: § Altered iron homeostatic mechanisms drive senescent cells to acquire profound levels of intracellular iron · plain

  “senescent MEFs (MEF IR) had markedly elevated IRP2 expression, consistent with having elevated TfR1 but not with elevated ferritin and ferroportin (Fig. 3A).”

In the paper

“The iron accumulation was reliant on p53-mediated senescence induction and was not indirectly caused by irradiation (Fig. S1E).”

In the paper

“Total cellular protein was slightly elevated (~ 1.3-fold) in senescent MEFs (MEF IR) (Fig. S1G), but could not account for the magnitude of increased intracellular iron (~ 20-fold) (Fig. 1A(iii)).”

In the paper

“Promoting ferritin degradation by using the autophagy activator rapamycin averted the iron accumulation phenotype of senescent cells, preventing the increase of TfR1, ferritin and intracellular iron, but failed to re-sensitize these cells to ferroptosis.”

In the paper

“the diameter of adhered senescent MEFs (at 21 days post-irradiation) was approximately twice that of primary non-irradiated MEFs (MEF PRI) (Fig. S1F). However, diameters of suspended cells measured following dissociation of adherent cells were closely aligned (Fig. S1G).”

In the paper

“Immortalised primary MEFs (MEF-LT) transduced with retroviruses containing HRasV12 showed no signs of cellular senescence and accordingly no iron accumulation (Fig. 1C(ii)).”

In the paper

“Senescent MEFs remain viable (Fig. S1B) and can be metabolically active in culture for many months [2].”

What the sources say

• Not checked yetcites [2] van Deursen, 2014, The role of senescent cells in ageing, Nature source

In the paper

“these human cell lines both displayed a substantial increase in intracellular ferritin (Fig. 3B(i),(ii)), consistent with concurrent iron accumulation (Fig. 2).”

• Also stated in: § Altered iron homeostatic mechanisms drive senescent cells to acquire profound levels of intracellular iron · plain

  “when senescence in MEFs was induced through continual passaging (REP), there was likewise a marked elevation in ferritin (Fig. 3B(iii)) corresponding to the iron accumulation (Fig. 1B).”

In the paper

“Finally, the enrichment of senescent cells in mouse ageing hepatic tissue was found to accompany iron accumulation, an elevation in ferritin and mirrored our observations using cultured senescent cells.”

In the paper

“MEFs that underwent senescence-bypass [NIH(3T3)] had intracellular iron levels comparable to that of primary MEFs (MEF PRI).”

• Also stated in: § Senescent cells accumulate large amounts of intracellular iron · plain

  “immortalised MEFs (MEF LT) at passage 7 had intracellular iron levels comparable to that of primary MEFs (MEF PRI).”

In the paper

“The accumulation of intracellular iron (Fig. 4B) occurred in parallel with the formation of senescent cells and reflected the percentage of senescent cells at days 7 (>50%) and 14 (> 80%) post-irradiation (Fig. 4A).”

• Also stated in: § Cellular senescence precedes iron accumulation and provides resistance to iron induced toxicity · plain

  “However, the amount of accumulated iron between days 14 and 21 plateaued.”

In the paper

“Senescent cells paradoxically had increased TfR1 and ferritin, coupled with reduced ferroportin at the plasma membrane (Fig. 3A,Figs. S2 and S3C).”

In the paper

“under the same treatment conditions, senescent MEFs (14 days post-irradiation) further increased TfR1 (5 µM FAC) and likewise ferritin (Fig. 4E(ii)).”

In the paper

“there was a further dose-dependent increase in the capacity of senescent MEFs to accumulate iron, with cells accumulating up to ~ 3-fold more (with 40 µM FAC) when compared with senescent cells cultured in basal medium and ~ 30-fold more when compared with primary MEFs cultured in basal medium (Fig. 4D).”

In the paper

“LC3-II also accumulated in replicative senescent MEFs (MEF REP), concomitant with elevated ferritin (Fig. S3C).”

In the paper

“primary MEFs with augmented intracellular iron (following 24 h FAC treatments) (Fig. 4D) had reduced TfR1 and upregulated ferritin in order to counteract toxicity (Fig. 4E(i)).”

In the paper

“Stored iron in senescent MEFs once accumulated is highly resistant to chelation.”

• Also stated in: § Cellular senescence precedes iron accumulation and provides resistance to iron induced toxicity · plain

  “Senescent MEFs (21 days post-irradiation) treated with Dfp (50 µM) for 24 h showed (i) only a marginal decrease in intracellular iron as determined by ICP-MS.”

• Also stated in: § Cellular senescence precedes iron accumulation and provides resistance to iron induced toxicity · boosted

  “Western blot analyses and densitometry showed a negligible effect of Dfp treatment on ferritin level of senescent MEFs.”

In the paper

“However, while senescent cells had barely detectable ISCU, consistent with deficient cellular iron, this was coupled with markedly reduced IRP1”

In the paper

“Furthermore, ferritin levels remained responsive in senescent cells, further increasing in iron supplemented media and affording greater tolerance to iron-induced toxicity (Fig. 4E(ii), F).”

In the paper

“Removal of p16-positive senescent cells in ageing mice delayed tumourigenesis and attenuated age-related deterioration of several organs, including kidney, heart and adipose tissue, without adverse side effects [3].”

What the sources say

• Not checked yetcites [3] Baker, 2016, Naturally occurringp16(Ink4a)-positive cells shorten healthy lifespan, Nature source

In the paper

“Furthermore, a median lifespan extension was observed, indicating that p16-positive senescent cells negatively impact longevity [3].”

What the sources say

• Not checked yetcites [3] Baker, 2016, Naturally occurringp16(Ink4a)-positive cells shorten healthy lifespan, Nature source

In the paper

“Therefore, ferritin may be a marker of cellular senescence and associated iron accumulation.”

In the paper

“Impaired ferritin degradation explains the iron accumulation phenotype of senescent cells, whereby iron is effectively trapped in ferritin creating a perceived cellular deficiency.”

In the paper

“Iron accumulation occurs in replicative senescent fibroblasts in vitro [35] and the iron storage protein ferritin is enriched in ageing tissues [36], [37].”

What the sources say

• Not checked yetcites [36] Ott, 2016, Macroautophagy is impaired in old murine brain tissue as well as in senescent human fibroblasts, Redox Biol. source
• Not checked yetcites [37] DeRuisseau, 2013, Aging-related changes in the iron status of skeletal muscle, Exp. Gerontol. source

In the paper

“Iron accumulation in senescent cells was driven by impaired ferritinophagy, a lysosomal process that promotes ferritin degradation and ferroptosis.”

In the paper

“Age-dependent accumulation of iron in various tissues has been reported to occur separately to the enrichment of senescent cells [11], [12], [16], [17], [18], [19].”

What the sources say

• Not checked yetcites [11] Fairweather-Tait, 2014, Iron status in the elderly, Mech. Ageing Dev. source
• Not checked yetcites [12] Xu, 2012, Impaired iron status in aging research, Int. J. Mol. Sci. source
• Not checked yetcites [16] Hahn, 2009, Age-dependent and gender-specific changes in mouse tissue iron by strain, Exp. Gerontol. source

In the paper

“Diseases associated with the accumulation of senescent cells, such as neurodegenerative disorders (e.g. Alzheimer's and Parkinson's) [20], [21], [22], osteoarthritis [23], [24] and idiopathic pulmonary fibrosis [25], also exhibit iron dyshomeostasis where often iron burden correlates with disease severity [14], [15], [26], [27], [28], [29], [30], [31], [32], [33], [34].”

What the sources say

• Not checked yetcites [20] Chinta, 2015, Cellular senescence and the aging brain, Exp. Gerontol. source
• Not checked yetcites [21] Bhat, 2012, Astrocyte senescence as a component of Alzheimer's disease, PLoS One source
• Not checked yetcites [22] Chinta, 2013, Environmental stress, ageing and glial cell senescence: a novel mechanistic link to Parkinson's disease?, J. Intern. Med. source

In the paper

“For instance, ferritin (iron storage) levels provided a robust biomarker of cellular senescence, for associated iron accumulation and for resistance to iron-induced toxicity.”

• Also stated in: § Altered iron homeostatic mechanisms drive senescent cells to acquire profound levels of intracellular iron · hedged

  “Therefore, ferritin may be a marker of cellular senescence and associated iron accumulation.”

In the paper

“Therefore, homeostatic mechanisms in senescent MEFs are geared for continual uptake and sequestration of milieu iron and afford cells resistance to toxicity from excess iron.”

In the paper

“Senescent cells can impair tissue function in ageing despite their relatively low abundance (< 15%) [3], [4].”

What the sources say

• Not checked yetcites [3] Baker, 2016, Naturally occurringp16(Ink4a)-positive cells shorten healthy lifespan, Nature source
• Not checked yetcites [4] Baker, 2011, Clearance of p16Ink4a-positive senescent cells delays ageing-associated disorders, Nature source

In the paper

“Ferroportin is therefore unlikely to participate in effective iron efflux and consequently iron accumulation prevails through enhanced uptake and sequestration.”

In the paper

“Taken together, these results demonstrate that lysosomal impairment is a feature of cellular senescence and is associated with ferritin accumulation (impaired ferritinophagy) and resistance to ferroptosis.”

In the paper

“Ferritinophagy, the process of ferritin being sequestered into autophagosomes and delivered to lysosomes for degradation, is important for liberating iron from ferritin and thus for maintaining cellular iron homeostasis [51], [53], [54], [55].”

What the sources say

• Not checked yetcites [51] Asano, 2011, Distinct mechanisms of ferritin delivery to lysosomes in iron-depleted and iron-replete cells, Mol. Cell. Biol. source
• Not checked yetcites [53] Mancias, 2014, Quantitative proteomics identifies NCOA4 as the cargo receptor mediating ferritinophagy, Nature source
• Not checked yetcites [54] Kidane, 2006, Release of iron from ferritin requires lysosomal activity, Am. J. Physiol. Cell Physiol. source

In the paper

“In mammalian cells, ferritins assemble to form large (480 kDa) complexes with cavities capable of accommodating up to 4500 atoms of iron and function to modulate iron bioavailability and detoxification within cells [47].”

What the sources say

• Not checked yetcites [47] MacKenzie, 2008, Intracellular iron transport and storage: from molecular mechanisms to health implications, Antioxid. Redox Signal. source

In the paper

“Together these results demonstrate that cellular senescence is associated with impaired ferritinophagy, explaining the associated iron-accumulation phenotype.”

In the paper

“Increased cellular iron uptake positively regulates ferritin expression, both at the transcriptional and translational levels, to afford protection from labile iron-mediated oxidative stress [38].”

What the sources say

• Not checked yetcites [38] Freund, 2012, Lamin B1 loss is a senescence-associated biomarker, Mol. Biol. Cell. source

In the paper

“which may provide a robust biomarker for cellular senescence and for associated iron accumulation (Figs. 3A,B,4C,E,6C,D).”

In the paper

“Taken together, the enrichment of senescent cells in ageing hepatic tissue was found to accompany iron accumulation, an elevation in the iron-storage ferritin protein and mirrored our observations in vitro using cultured senescent cells.”

In the paper

“Most cells subsequently down-regulate iron uptake mechanisms, particularly TfR1 and up-regulate iron efflux via ferroportin in order to regain homeostatic levels (Fig. 4E(i)) [47].”

What the sources say

• Not checked yetcites [47] MacKenzie, 2008, Intracellular iron transport and storage: from molecular mechanisms to health implications, Antioxid. Redox Signal. source

In the paper

“Rapamycin selectively activates autophagy through inhibiting the mTOR pathway [60] and can extend the lifespan of mice [79].”

What the sources say

• Not checked yetcites [60] Sarkar, 2009, Rapamycin and mTOR-independent autophagy inducers ameliorate toxicity of polyglutamine-expanded huntingtin and related proteinopathies, Cell Death Differ. source
• Not checked yetcites [79] Harrison, 2009, Rapamycin fed late in life extends lifespan in genetically heterogeneous mice, Nature source

In the paper

“However, senescent cells having perturbed ferritin degradation sequester iron (trapped in ferritin), creating a perpetual state of deficiency and a cycle promoting continual iron acquisition.”

In the paper

“Erastin induces ferroptosis through silencing SLC7A11 [84] and was recently demonstrated to enhance iron bioavailability through autophagic/lysosomal degradation of ferritin and its cargo receptor NCOA4 [63].”

What the sources say

• Not checked yetcites [84] Dixon, 2014, Pharmacological inhibition of cystine-glutamate exchange induces endoplasmic reticulum stress and ferroptosis, eLife source
• Not checked yetcites [63] Gao, 2016, Ferroptosis is an autophagic cell death process, Cell Res. source

In the paper

“Ferritin is selectively targeted for autophagic/lysosomal degradation by the cargo receptor NCOA4 [53], a process required for liberating iron making it bioavailable to the cell [51], [53], [65].”

What the sources say

• Not checked yetcites [53] Mancias, 2014, Quantitative proteomics identifies NCOA4 as the cargo receptor mediating ferritinophagy, Nature source
• Not checked yetcites [51] Asano, 2011, Distinct mechanisms of ferritin delivery to lysosomes in iron-depleted and iron-replete cells, Mol. Cell. Biol. source
• Not checked yetcites [65] Hou, 2016, Autophagy promotes ferroptosis by degradation of ferritin, Autophagy source

In the paper

“which in contrast to erastin induces ferroptosis through direct inhibition of glutathione peroxidase 4 (GPX4) without dependance upon system Xc- inhibition or glutathione depletion [82].”

What the sources say

• Not checked yetcites [82] Cao, 2016, Mechanisms of ferroptosis, Cell. Mol. Life Sci.: CMLS source

In the paper

“Additionally, rapamycin treatment may lead to autophagic degradation of TfR1 or modulate levels by enhancing degradation of TfR1 mRNA [78].”

What the sources say

• Not checked yetcites [78] Bayeva, 2012, mTOR regulates cellular iron homeostasis through tristetraprolin, Cell Metab. source

In the paper

“Autophagy involves the delivery of cytoplasmic substrates (cellular proteins and damaged organelles) to lysosomes for degradation and impairment of this process is associated with premature ageing and age-associated decline in tissue function [58], [71].”

What the sources say

• Not checked yetcites [58] Tanida, 2005, Lysosomal turnover, but not a cellular level, of endogenous LC3 is a marker for autophagy, Autophagy source
• Not checked yetcites [71] Rubinsztein, 2011, Autophagy and aging, Cell source

In the paper

“Impaired ferritinophagy traps iron in ferritin creating a perceived cellular deficiency, which in turn causes concomitant changes in the levels of iron regulatory proteins.”

In the paper

“Ferritin and ferroportin can be regulated through mRNA stability or post-translationally through protein turnover [85], [86].”

What the sources say

• Not checked yetcites [85] Ward, 2012, Ferroportin-mediated iron transport: expression and regulation, Biochim. Biophys. Acta source
• Not checked yetcites [86] Drysdale, 1966, Regulation of synthesis and turnover of ferritin in rat liver, J. Biol. Chem. source

In the paper

“Coincidently, impaired autophagy in senescent cells has previously been shown to reduce ferritin turnover, but in this study intracellular iron levels or the levels of major iron homeostasis proteins were not evaluated [77].”

What the sources say

• Not checked yetcites [77] Ott, 2016, Reduced autophagy leads to an impaired ferritin turnover in senescent fibroblasts, Free Radic. Biol. Med. source

In the paper

“Additionally, lysosomal dysfunction can precede senescence development and drive the associated phenotypic changes [57], [73].”

What the sources say

• Not checked yetcites [57] Tai, 2017, Autophagy impairment with lysosomal and mitochondrial dysfunction is an important characteristic of oxidative stress-induced senescence, Autophagy source
• Not checked yetcites [73] Kang, 2011, Autophagy impairment induces premature senescence in primary human fibroblasts, PLoS One source

In the paper

“Nonetheless, lysosomal dysfunction in senescent cells can account for ferritin and ferroportin accumulation, as both proteins are degraded through the autophagic pathway [51], [89].”

What the sources say

• Not checked yetcites [51] Asano, 2011, Distinct mechanisms of ferritin delivery to lysosomes in iron-depleted and iron-replete cells, Mol. Cell. Biol. source
• Not checked yetcites [89] Nemeth, 2004, Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization, Science source

In the paper

“Distinctly, ferroptosis can be initiated through repression of the p53 target, SLC7A11, which encodes a component of the cysteine/glutamate antiporter (system Xc-), resulting in iron-dependent accumulation of ROS and glutathione (antioxidant) depletion [62], [82].”

What the sources say

• Not checked yetcites [62] Dixon, 2012, Ferroptosis: an iron-dependent form of nonapoptotic cell death, Cell source
• Not checked yetcites [82] Cao, 2016, Mechanisms of ferroptosis, Cell. Mol. Life Sci.: CMLS source

In the paper

“Depletion of lysosomal-associated membrane protein 2 (LAMP2), which is critical for fusion between autophagosomes and lysosomes, can induce cellular senescence [57], [73], as can pharmacological inhibition of lysosomal activity (hydroxychloroquine & leupeptin treatment) [57].”

What the sources say

• Not checked yetcites [57] Tai, 2017, Autophagy impairment with lysosomal and mitochondrial dysfunction is an important characteristic of oxidative stress-induced senescence, Autophagy source
• Not checked yetcites [73] Kang, 2011, Autophagy impairment induces premature senescence in primary human fibroblasts, PLoS One source

In the paper

“In this situation, IRP1 usually loses its iron-sulfur cluster and aconitase activity and binds IREs with high affinity [48], [50].”

What the sources say

• Not checked yetcites [48] Rouault, 2006, The role of iron regulatory proteins in mammalian iron homeostasis and disease, Nat. Chem. Biol. source
• Not checked yetcites [50] Rouault, 2015, Mammalian iron-sulphur proteins: novel insights into biogenesis and function, Nat. Rev. Mol. Cell Biol. source

In the paper

“Consistent with our findings (Fig. 5,Fig. S3), lysosomal dysfunction has been documented in replicative [74] and oxidative stress-induced senescence [57] and in both cases was associated with the buildup of autophagosomes and related markers (e.g. LC3-II, p62).”

What the sources say

• Not checked yetcites [74] Lin, 2015, Downregulation of dynamin-related protein 1 contributes to impaired autophagic flux and angiogenic function in senescent endothelial cells, Arterioscler. Thromb. Vasc. Biol. source
• Not checked yetcites [57] Tai, 2017, Autophagy impairment with lysosomal and mitochondrial dysfunction is an important characteristic of oxidative stress-induced senescence, Autophagy source

In the paper

“GATA4 in turn activates the NF-kB transcription factor to initiate SASP and facilitate senescence progression.”

What the sources say

• Not checked yetcites [76] Kang, 2015, The DNA damage response induces inflammation and senescence by inhibiting autophagy of GATA4, Science source

In the paper

“Autophagy impairment incurred through lysosomal dysfunction has recently been described in cellular senescence and shown to regulate SASP [57], [72], [73], [74], [75].”

What the sources say

• Not checked yetcites [57] Tai, 2017, Autophagy impairment with lysosomal and mitochondrial dysfunction is an important characteristic of oxidative stress-induced senescence, Autophagy source
• Not checked yetcites [72] Han, 2016, AMPK activation protects cells from oxidative stress-induced senescence via autophagic flux restoration and intracellular NAD(+) elevation, Aging Cell source
• Not checked yetcites [73] Kang, 2011, Autophagy impairment induces premature senescence in primary human fibroblasts, PLoS One source

In the paper

“While IRP2 can mediate the degradation of ferritin and ferroportin mRNA [48], this must be insufficient to prevent their biosynthesis in the context of senescent cells.”

What the sources say

• Not checked yetcites [48] Rouault, 2006, The role of iron regulatory proteins in mammalian iron homeostasis and disease, Nat. Chem. Biol. source

In the paper

“Cell death elicited by ferroptosis-inducing compounds (FINs) (e.g. erastin and RSL3) can also be mitigated through various iron chelators (Dfo, 2,2-bipyridile or compound 311) [62], [66], [81].”

What the sources say

• Not checked yetcites [62] Dixon, 2012, Ferroptosis: an iron-dependent form of nonapoptotic cell death, Cell source
• Not checked yetcites [66] Yang, 2008, Synthetic lethal screening identifies compounds activating iron-dependent, nonapoptotic cell death in oncogenic-RAS-harboring cancer cells, Chem. Biol. source
• Not checked yetcites [81] Reed, 2012, Ironing out cell death mechanisms, Cell source

In the paper

“Additionally, ISCU levels are suppressed by iron deprivation, to decrease iron utilization by curtailing iron-sulfur cluster biogenesis [90].”

What the sources say

• Not checked yetcites [90] Tong, 2006, Functions of mitochondrial ISCU and cytosolic ISCU in mammalian iron-sulfur cluster biogenesis and iron homeostasis, Cell Metab. source

In the paper

“This scenario accounts for the profound iron accumulation observed in senescent cells (up to 20-fold) and for their capacity to extract further iron from enriched media (Fig. 4E(ii)).”

In the paper

“Cells are also desensitized to ferroptosis through genetic silencing of iron uptake (TfR1), metabolism (IRP2 and ISCU) and storage (ferritin) genes [62], [66], [82], or through depletion of transferrin in the extracellular environment [83].”

What the sources say

• Not checked yetcites [62] Dixon, 2012, Ferroptosis: an iron-dependent form of nonapoptotic cell death, Cell source
• Not checked yetcites [66] Yang, 2008, Synthetic lethal screening identifies compounds activating iron-dependent, nonapoptotic cell death in oncogenic-RAS-harboring cancer cells, Chem. Biol. source
• Not checked yetcites [82] Cao, 2016, Mechanisms of ferroptosis, Cell. Mol. Life Sci.: CMLS source

In the paper

“Ferroptosis, a unique cell death pathway distinct from apoptosis [62], [66], [80], is reliant on the availability of iron [62], [66], [81] liberated through ferritinophagy [63].”

What the sources say

• Not checked yetcites [62] Dixon, 2012, Ferroptosis: an iron-dependent form of nonapoptotic cell death, Cell source
• Not checked yetcites [66] Yang, 2008, Synthetic lethal screening identifies compounds activating iron-dependent, nonapoptotic cell death in oncogenic-RAS-harboring cancer cells, Chem. Biol. source
• Not checked yetcites [80] Yagoda, 2007, RAS-RAF-MEK-dependent oxidative cell death involving voltage-dependent anion channels, Nature source

In the paper

“The mTOR pathway is a negative regulator of autophagy and is implicated in cellular senescence [67], most notably through SA-βgal activity and the expression of p16 and p21 markers [67], [68].”

What the sources say

• Not checked yetcites [67] Xu, 2014, mTOR signaling from cellular senescence to organismal aging, Aging Dis.
• Not checked yetcites [68] Laberge, 2015, MTOR regulates the pro-tumorigenic senescence-associated secretory phenotype by promoting IL1A translation, Nat. Cell Biol. source

In the paper

“bafilomycin A1 (100 nM), an inhibitor of late-phase autophagy (prevents fusion of autophagosomes and lysosomes) [61]”

What the sources say

• Not checked yetcites [61] Yamamoto, 1998, Bafilomycin A1 prevents maturation of autophagic vacuoles by inhibiting fusion between autophagosomes and lysosomes in rat hepatoma cell line, H-4-II-E cells, Cell Struct. Funct. source

In the paper

“Note that the ferritin antibody was diluted in these experiments to facilitate the exclusive detection of ferritin overexpressing cells.”

In the paper

“Quadruplicate determinations of iron concentration was performed for each sample.”

In the paper

“Control non-irradiated cell lines were cultured to equivalent confluence and otherwise handled in the same manner as irradiated cells.”

In the paper

“Loss of pS6 promotes autophagosome formation [69].”

What the sources say

• Not checked yetcites [69] Blommaart, 1995, Phosphorylation of ribosomal protein S6 is inhibitory for autophagy in isolated rat hepatocytes, J. Biol. Chem. source

In the paper

“At least three independent experiments were used for all comparisons.”

In the paper

“This study was approved by the Deakin University Animal Ethics Committee (AEC) (Id#G01-2014).”

In the paper

“We used rapamycin (100 nM), which selectively activates autophagy through inhibiting the mTOR pathway [60] to activate autophagy in primary MEFs (MEF PRI), significantly increasing the LC3-II: LC3-I ratio (Fig. 5C).”

What the sources say

• Not checked yetcites [60] Sarkar, 2009, Rapamycin and mTOR-independent autophagy inducers ameliorate toxicity of polyglutamine-expanded huntingtin and related proteinopathies, Cell Death Differ. source

In the paper

“two structurally different inducers of ferroptosis that affect distinct pathways [66].”

What the sources say

• Not checked yetcites [66] Yang, 2008, Synthetic lethal screening identifies compounds activating iron-dependent, nonapoptotic cell death in oncogenic-RAS-harboring cancer cells, Chem. Biol. source

In the paper

“Elevated p62 levels were previously observed in oxidative stress-induced senescent cells [57], and consistent with this study, we demonstrated that our senescent MEFs (MEF IR) likewise had markedly elevated levels of p62 when compared to primary MEFs (MEF PRI) (Fig. 5D).”

What the sources say

• Not checked yetcites [57] Tai, 2017, Autophagy impairment with lysosomal and mitochondrial dysfunction is an important characteristic of oxidative stress-induced senescence, Autophagy source

In the paper

“an iron-dependent autophagic cell death program [62], [63], [64] that can be inhibited in MEFs by genetically inactivating autophagy or ferritinophagy [65].”

What the sources say

• Not checked yetcites [62] Dixon, 2012, Ferroptosis: an iron-dependent form of nonapoptotic cell death, Cell source
• Not checked yetcites [63] Gao, 2016, Ferroptosis is an autophagic cell death process, Cell Res. source
• Not checked yetcites [64] Wolpaw, 2011, Modulatory profiling identifies mechanisms of small molecule-induced cell death, Proc. Natl. Acad. Sci. USA source