Unc-51-like Kinase 1 Research Articles

Inhibition of autophagy enhances the anticancer effect of enzalutamide on bladder cancer

BackgroundEmerging preclinical evidence suggests a critical role for androgen-mediated androgen receptor (AR) signaling in bladder cancer progression. However, researchers have not determined whether autophagy modulates the efficacy of an enzalutamide (ENZ) treatment in subjects with advanced bladder cancer. In this study, we investigated the synergistic effect of ENZ and autophagy inhibitors on bladder cancer. MethodsENZ was used as an anti-AR drug, and chloroquine (CQ), 3-methyladenine (3-MA), and bafilomycin A1 (BAF) were used as autophagy inhibitors. J82, T24, and UMUC3 cell lines were used as models of bladder cancer. A bifluorescence autophagy system with the mRFP-GFP-LC3 plasmid was used to evaluate autophagy flux. Protein and mRNA levels were detected using Western blotting and qPCR, respectively. A Cell Counting Kit-8 (CCK-8) assay, colony assay, and flow cytometry analysis were used to evaluate cell proliferation and apoptosis. Four-week-old BALB/c athymic nude mice were used in the in vivo assay. ResultsBased on the results obtained using the bifluorescence autophagy system, ENZ (10–20 μM) significantly facilitated the accumulation of autophagosomes and autolysosomes in the cytoplasm of J82 and T24 cells. Additionally, ENZ significantly increased the expression of autophagy-related genes (AMP-dependent protein kinase (AMPK), autophagy-related gene 5 (ATG5), microtubule-associated protein light chain 3B (LC3B), and UNC-51-like kinase 1 (ULK1)) and proteins (microtubule-associated protein 1 light chain 3-II/I (LC3-II/I), ATG5, and phosphorylated AMP-dependent protein kinase α (p-AMPKα)). The administration of ENZ monotherapy (10–20 μM) to J82 and T24 cells failed to alter proliferation and apoptosis. Concurrent treatment with ENZ and autophagy inhibitors distinctly triggered apoptosis and inhibited proliferation. Genetic inhibition of autophagy by specifically blocking ATG5 with siRNA also increased ENZ-induced apoptosis in J82 and T24 cells. In vivo, concurrent treatment with ENZ (25 mg/kg/day) and CQ (10 mg/kg/day) improved the therapeutic sensitivity by decreasing tumor growth and apoptosis. Additionally, overexpression of AR suppressed ENZ-induced autophagy-related genes (LC3-II/I, ATG5, and p-AMPKα) in T24 cells, and CQ exerted synergistic effects with ENZ to suppressed AR-responsive genes expression (KLK2 and KLK3) in bladder cancer. In UMUC3 cells, ENZ monotherapy directly induced anticancer effects, and concurrent treatment with ENZ and CQ also had a synergistic effect on proliferation and apoptosis. ConclusionsAutophagy may be a potential mechanism underlying ENZ-resistant bladder cancer. Blockade of autophagy significantly increased ENZ-induced apoptosis in bladder cancer. Thus, concurrent treatment with autophagy inhibitors and ENZ may be a novel therapeutic strategy for bladder cancer.

Downregulated miR‑302d‑3p promotes chondrocyte proliferation and migration by regulation of Unc‑51‑like kinase 1.

Osteoarthritis (OA) is a common musculoskeletal disease and is related to the function of chondrocytes. The aim of the present study was to investigate the effects of miR-302d-3p on chondrocytes. Quantitative PCR (qPCR) was conducted to detect mRNA expression, while western blotting was performed to investigate protein expression in these cells. RNAs mimics, inhibitors and small interfering (si)RNAs were respectively transfected into chondrocytes (CHON-001 cell line), after which, a Cell Counting Kit-8 assay was performed to detect chondrocyte viability. Giemsa staining of the cells was also conducted to analyze the colony formation ability of the cells. Additionally, cell apoptosis was evaluated with an apoptosis detection kit using flow cytometry. A scratch-wound assay was conducted to investigate cell migration. Bioinformatics analysis using TargetScan 7.2 revealed the potential the target gene of microRNA (miR)-302d-3p; a dual luciferase reporter assay determined the target gene. Suppression of miR-302d-3p increased the viability of cells, cell colony number and migration; CHON-001 cell apoptosis was also inhibited. miR-302d-3p mimics decreased the luciferase activity of reporter plasmids containing the wild-type 3′-untranslated region of Unc-51-like kinase 1 (ULK1). siULK1 decreased CHON-001 cell viability and migration. Furthermore, siULK1 promoted the expression of phosphorylated IκBα and p65, while miR-302d-3p inhibitor suppressed the expression of phosphorylated IκBα and p65. Inhibition of miR-302d-3p could promote the proliferation and migration, and inhibit the apoptosis of chondrocytes, potentially by upregulating ULK1; thus, inflammation may be suppressed. The findings of the present study suggest miR-302d-3p and ULK1 as potential therapeutic targets for the prevention and treatment of OA.

Tanshinone IIA Restores Dynamic Balance of Autophagosome/Autolysosome in Doxorubicin-Induced Cardiotoxicity via Targeting Beclin1/LAMP1.

Clinical use of the anti-cancer drug doxorubicin (DOX) is largely limited due to its severe cardiotoxicity. Dysregulation of autophagy is implicated in DOX-induced cardiotoxicity (DIC). Prior studies have indicated that Beclin1 and lysosomal-associated membrane proteins-1 (LAMP1) are critical mediators of autophagy. In this work, by assessing autophagic flux in a DOX-stimulated H9C2 model, we observed autolysosome accumulation caused by interruption of autolysosome degradation. Tanshinone IIA (TSA) is a well-known small molecule that exerts impressive cardioprotective effects on heart failure. Here, we investigated the regulation of TSA in DOX-treated zebrafish, mice, and H9C2 models. Results demonstrated that TSA remarkably improved heart function and reversed pathological changes in vivo, while TSA restored autophagic flux by promoting autolysosome degradation and autophagosome formation. Further experiments demonstrated that these effects were mediated through upregulation of Beclin1 and LAMP1. The mTOR agonist MHY1485 was shown to abrogate the effect of TSA via the UNC-51-like kinase 1 (ULK1)-Beclin1/TFEB-LAMP1 signaling pathway in vitro, demonstrating that TSA protects against DIC by promoting autophagy via the Beclin1/LAMP1 signaling pathway. We further employed a U87 model to assess whether TSA would compromise the antitumor activity of DOX. Intriguingly, the co-treatment of TSA was able to synergistically inhibit proliferative activity. Collectively, in this study we uncover the novel insight that TSA is able to reduce the cardiotoxicity of DOX without compromising antitumor activity.

Progress of researches on acupuncture treatment of cerebral ischemia-reperfusion injury by regulating autophagy in the ischemic cerebral tissue

Excessive autophagy is one of the crucial factors of cerebral ischemia-reperfusion injury (CIRI), which has been demonstrated to be one of the targets for acupuncture treatment of ischemic stroke. In the present paper, we make a review about the development of acupuncture intervention induced improvement of CIRI (such as reducing the infarction area, improving learning-memory ability and motor function) by regulating autophagy in animal studies. Outcomes showed that acupuncture intervention can function in 1) inhibiting CIRI-induced increase of the number of lysosomes and autophagic lysosomes, and relieving structural injury of mitochondria, and reducing the number of autophagosome in the central region of the ischemic cerebral cortex tissue; 2) down-regulating the expression of microtubule-associated protein Ⅱ light chain 3 (LC3Ⅱ) and the ratio of LC3-Ⅱ/LC3-Ⅰ in the ischemic cerebral region, and 3) regulating the expression of Beclin 1 (autophagy-related gene), promoting the expression of P62 (autophagy-related adaptor protein). In addition, acupuncture can also regulate phosphoinositide 3 kinase (PI3K)- protein kinase B (AKT)- mammalian target of rapamycin complex 1(mTOR) signaling at different time-points (down-regulation at the early stage and up-regulation at the later stage), and activating AMP-activated protein kinase (AMPK)-mTOR- UNC51-like kinase-1 signaling to relieve cerebral ischemic injury. These results reveal some mechanisms of acupuncture therapy underlying improvement of CIRI and provide experimental basis for clinical application of acupuncture therapy in the treatment of ischemic stroke.

Inhibiting TRPV1-Mediated Autophagy Attenuates Nitrogen Mustard-Induced Dermal Toxicity

There is currently no satisfactory therapy for nitrogen mustard (NM)-caused dermal toxicity, for poor understanding of the exact mechanisms. Autophagy has been found to play important roles in physical or chemical exposure-caused cutaneous injuries. Herein, we initially confirmed that NM dose-dependently caused cell death in keratinocytes. The LC3B2 (light chain 3 beta 2) formation and SQSTM1/p62 (sequestosome 1) degradation and the formation of autophagosomes were also dose-dependently upregulated by NM. And chloroquine treatment resulted in further accumulation of LC3B2 in NM-treated keratinocytes. Suppression of autophagy by 3-methyladenine and chloroquine or ATG5 siRNA attenuated NM-caused cell death in keratinocytes. Furthermore, NM increased TRPV1 (Transient receptor potential vanilloid 1) expression, intracellular Ca2+ content, and the activity of CaMKKβ (Ca2+/Calmodulin-Dependent Kinase Kinase β), AMP-activated protein kinase (AMPK), ULK1 (unc-51-like kinase 1) and mTOR (mammalian target of rapamycin). NM-induced autophagy in keratinocytes was abolished in the presence of inhibitors of TRPV1 (capsazepine), CaMKKβ (STO-609), or AMPK (compound C) as well as TRPV1, CaMKKβ, and AMPK siRNA transfection. Additionally, mTOR inhibitor (rapamycin) had no significant effect on NM-stimulated autophagy and cell death in keratinocytes. Finally, the results of in vivo study in NM-treated skin tissues were consistent with the findings of in vitro study. In conclusion, NM caused dermal toxicity by overactivating autophagy through the activation of TRPV1-Ca2+-CaMKKβ-AMPK-ULK1 signaling pathway. These suggest that blocking TRPV1-dependent autophagy could be a potential treatment strategy for NM-caused skin injury. Funding: This work was supported by the National Natural Science Foundation of China (grant number: 1703268), National Postdoctoral Program for Innovative Talents (BX20180378) and the Excellent Youth Foundation of the Amy Medical University (2017). Declaration of Interest: The authors declare no conflicts of interest. Ethical Approval: All animal experiments were carried out in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals by the National Institutes of Health and were approved by the Animal Care and Use Committee of the Amy Medical University (Chongqing, China; approval no. SYXC-2016-00115).

Effects of Exercise Training on the Autophagy-Related Muscular Proteins Expression in Ovariectomized Rats.

Ovariectomy disrupts estrogen production and homeostasis. However, whether exercise training (ET) could counteract the ovariectomy-induced effect on muscular autophagy has remained elusive. This study examined muscular autophagy in ovariectomized (OVX) rats following 8 weeks of swimming ET. Here, 40 6-month-old female Sprague-Dawley rats were randomly divided into five groups: sham-operated control (Sham), OVX control (OVX), OVX with 60-min ET (OVX-60ET), 90-min ET (OVX-90ET), and 120-min ET (OVX-120ET) for 6 days/week. According to the results of Western blotting, the expression levels of autophagy-related proteins in the OVX gastrocnemius muscle, including mammalian target of rapamycin, uncoordinated 51-like kinase 1, Beclin-1, autophagy-related gene (Atg-7), and microtubule-associated protein light chains 3 were significantly decreased (all P < 0.05), while there was an elevation on the p62 level. ET appreciably mitigated the OVX-induced negative effects on muscle quality and the autophagy pathway, which seemed to be dependent on ET volume. The most optimal outcomes were observed in the OVX-90ET group. The OVX-120 group had an adversely augmented catabolic process associated with gastrocnemius muscle atrophy. In conclusion, the expression levels of autophagy proteins are decreased in OVX rats, which can be appreciably mitigated following 8 weeks of swimming ET.

Modulation of mTOR and CREB pathways following mGluR5 blockade contribute to improved Huntington\u2019s pathology in zQ175 mice

Huntington’s disease (HD) is a neurodegenerative disorder caused by a genetic abnormality in the huntingtin gene that leads to a polyglutamine repeat expansion of the huntingtin protein. The cleaved polyglutamine expansion of mutant huntingtin (mHTT) protein can form aggregates strongly correlated with HD progression. We have previously shown that the inhibition of mGluR5 using CTEP, a selective negative allosteric mGluR5 modulator, can delay disease progression and reduce in mHTT aggregates in the zQ175 mouse model of HD. This was paralleled by enhanced catalytic activity of Unc-51-like kinase 1 (ULK1), a kinase modulated by mammalian target of rapamycin (mTOR) and key regulator of autophagy initiation. In the present study, we show that CTEP can correct aberrant phosphoinositide 3-kinase (PI3K)/Akt/mTOR signaling detected in zQ175 mice that may underlie the enhanced ULK1 activity and activation of autophagy. We also show that CTEP can facilitate cAMP response element-binding protein (CREB)-mediated expression of brain-derived neurotrophic factor (BDNF) to foster neuronal survival and reduce apoptosis. Taken together, our findings provide the molecular evidence for how targeting mGluR5 using a well-tolerated selective NAM can mitigate two critical mechanisms of neurodegeneration, autophagy and apoptosis.

Angiotensin II suppresses autophagy and disrupts ultrastructural morphology and function of mitochondria in mouse skeletal muscle.

Angiotensin II (ANG II)-induced skeletal muscle wasting is characterized by activation of the ubiquitin-proteasome system. However, the potential involvement of proteolytic system macroautophagy/autophagy in this wasting process remains elusive. Autophagy is precisely regulated to maintain cell survival and homeostasis; thus its dysregulation (i.e., overactivation or persistent suppression) could lead to detrimental outcomes in skeletal muscle. Here we show that infusion of ANG II for 7 days in male FVB mice suppressed autophagy in skeletal muscle. ANG II blunted microtubule-associated protein 1 light chain 3B (LC3B)-I-to-LC3B-II conversion (an autophagosome marker), increased p62/SQSTM1 (an autophagy cargo receptor) protein expression, and decreased the number of autophagic vacuoles. ANG II inhibited UNC-51-like kinase 1 via inhibition of 5'-AMP-activated kinase and activation of mechanistic target of rapamycin complex 1, leading to reduced phosphorylation of beclin-1Ser14 and Autophagy-related protein 14Ser29, suggesting that ANG II impairs autophagosome formation in skeletal muscle. In line with ANG II-mediated suppression of autophagy, ANG II promoted accumulation of abnormal/damaged mitochondria, characterized by swelling and disorganized cristae and matrix dissolution, with associated increase in PTEN-induced kinase 1 protein expression. ANG II also reduced mitochondrial respiration, indicative of mitochondrial dysfunction. Together, these results demonstrate that ANG II reduces autophagic activity and disrupts mitochondrial ultrastructure and function, likely contributing to skeletal muscle wasting. Therefore, strategies that activate autophagy in skeletal muscle have the potential to prevent or blunt ANG II-induced skeletal muscle wasting in chronic diseases. NEW & NOTEWORTHY Our study identified a novel mechanism whereby angiotensin II (ANG II) impairs mitochondrial energy metabolism in skeletal muscle. ANG II suppressed autophagosome formation by inhibiting the UNC-51-like kinase 1(ULK1)-beclin-1 axis, resulting in accumulation of abnormal/damaged and dysfunctional mitochondria and reduced mitochondrial respiratory capacity. Therapeutic strategies that activate the ULK1-beclin-1 axis have the potential to delay or reverse skeletal muscle wasting in chronic diseases characterized by increased systemic ANG II levels.

Molecular mechanisms of mycelium of Cordyceps sinensis ameliorating renal tubular epithelial cells aging induced by D-galactose via inhibiting autophagy-related AMPK/ULK1 signaling activation

To explore the effects and molecular mechanisms of mycelium of Cordyceps sinensis(MCs)improving renal tubular epithelial cells aging induced by D-galactose,the renal proximal tubular epithelial cells(NRK-52E cells)of rats in vitro were divided into the normal group(N),the D-gal model group(D),the low dose of MCs group(L-MCs),the medium dose of MCs group(M-MCs)and the high dose of MCs group(H-MCs),and treated by the different measures,respectively.More specifically,the NRK-52E cells in each group were separately treated by 1%fetal bovine serum(FBS)or D-galactose(D-gal,100 mmol·L~(-1))or D-gal(100 mmol·L~(-1))+MCs(20 mg·L~(-1))or D-gal(100 mmol·L~(-1))+MCs(40 mg·L~(-1))or D-gal(100 mmol·L~(-1))+MCs(80 mg·L~(-1)).After the intervention for24 h or 48 h,firstly,the effects of D-gal on the protein expression levels of klotho,P27 and P16,the staining of senescence-associatedβ-galactosidase(SA-β-gal)and the activation of adenosine monophosphate activated protein kinase(AMPK)/uncoordinated 51-like kinase 1(ULK1)signaling in the NRK-52E cells were detected,respectively.Secondly,the effects of MCs on the activation of the NRK-52E cells proliferation were investigated,respectively.Finally,the effects of MCs on the protein expression levels of klotho,P27,P16and microtubule-associated protein 1 light chain 3(LC3),the staining of SA-β-gal and the activation of AMPK/ULK1 signaling in the NRK-52E cells exposed to D-gal were examined severally.The results indicated that,for the NRK-52E cells,D-gal could cause aging,induce the protein over-expression levels of the phosphorylated AMPK(p-AMPK)and the phosphorylated ULK1(p-ULK1)and activate AMPK/ULK1 signaling pathway.The co-treatment of MCs at the medium and high doses and D-gal could significantly ameliorate the protein expression levels of klotho,P27,P16 and the staining of SA-β-gal,suggesting the anti-cell aging actions.In addition,the cotreatment of MCs at the medium and high doses and D-gal could obviously improve the protein expression levels of LC3,p-AMPK,and p-ULK1,inhibit the activation of AMPK/ULK1 signaling and increase autophagy.On the whole,for the renal tubular epithelial cells aging models induced by D-gal,MCs not only has the in vitro actions of anti-aging,but also intervenes aging process by inhibiting autophagy-related AMPK/ULK1 signaling activation,which may be the novel molecular mechanisms of MCs protecting against aging of the renal tubular epithelial cells.

Balancing mTOR Signaling and Autophagy in the Treatment of Parkinson's Disease.

The mammalian target of rapamycin (mTOR) signaling pathway plays a critical role in regulating cell growth, proliferation, and life span. mTOR signaling is a central regulator of autophagy by modulating multiple aspects of the autophagy process, such as initiation, process, and termination through controlling the activity of the unc51-like kinase 1 (ULK1) complex and vacuolar protein sorting 34 (VPS34) complex, and the intracellular distribution of TFEB/TFE3 and proto-lysosome tubule reformation. Parkinson’s disease (PD) is a serious, common neurodegenerative disease characterized by dopaminergic neuron loss in the substantia nigra pars compacta (SNpc) and the accumulation of Lewy bodies. An increasing amount of evidence indicates that mTOR and autophagy are critical for the pathogenesis of PD. In this review, we will summarize recent advances regarding the roles of mTOR and autophagy in PD pathogenesis and treatment. Further characterizing the dysregulation of mTOR pathway and the clinical translation of mTOR modulators in PD may offer exciting new avenues for future drug development.

ULK1 polymorphisms confer susceptibility to pulmonary tuberculosis in a Chinese population.

The autophagy pathway is a critical process in Mycobacterium tuberculosis infection, and can be regulated by uncoordinated 51-like kinase 1 (ULK1). We investigated the associations between single-nucleotide polymorphisms (SNPs) in ULK1 and risk of tuberculosis (TB) in a Chinese Han population. We recruited 380 pulmonary tuberculosis (PTB) cases, 242 extra-pulmonary tuberculosis (EPTB) cases and 606 healthy controls from a Chinese Han population and sequenced ULK1. Five SNPs in ULK1 were selected to investigate the correlations between ULK1 polymorphisms and TB susceptibility. The rs7138581 C allele was associated with a reduced risk of PTB (P = 0.001), whereas the rs9481 A allele was associated with an increased risk (P = 0.025). The rs7138581 CG genotype was significantly associated with a low risk of PTB, with a higher PTB disease severity in clinical parameters. Estimation of haplotype frequencies in ULK1 revealed a protective haplotype CCGAA (P = 0.007) and a potential risk haplotype TGAAA (P = 0.010) for PTB. These results demonstrated that ULK1 polymorphisms have significant associations with susceptibility to PTB.

Autophagy activity and expression pattern of autophagy-related markers in the podocytes of patients with lupus nephritis: association with pathological classification

Objective: To identify the significance of autophagy in lupus nephritis (LN). Methods: The number of autophagosomes in podocytes was counted and the expression of multiple molecular markers associated with autophagy was evaluated in LN specimens: in renal biopsy specimens from 90 patients with LN and 15 healthy controls, autophagosomes in podocytes were counted using transmission electron microscopy and the expression levels of four autophage related proteins including Beclin-1, microtubule-associated protein light chain 3 (LC3), autophagy-related gene 7 (Atg7), and UNC-51-like kinase 1 (ULK1) were measured using immunohistochemistry. Results: The number of autophagosomes in patients with LN types III, IV, and combined V–IV type were significantly higher than in controls (p < 0.0001; p < 0.0001; p = 0.009, respectively). However, the autophagosomes numbers in patients with II and V types LN were significantly lower than controls (both p < 0.0001). Various levels of marker expression were identified, and they correlated significantly with LN pathology classifications. Moreover, the percentage of marker expression in LN types III, IV and V-IV were significantly higher than controls (p < 0.05), while that in types II and V were lower than controls, although the difference for LC3 and ULK1 was not statistically significant. Conclusions: Autophagy activity and expression pattern of autophagy-related markers in podocytes were significantly positively correlated with LN of types III, IV, and V–IV, but negatively correlated with II and V types. Therefore autophagy could be a useful predictor of LN pathology type, and be informative and helpful in the development of treatment strategies in clinical settings.

ULK1 O-GlcNAcylation Is Crucial for Activating VPS34 via ATG14L during Autophagy Initiation

Unc-51-like-kinase 1 (ULK1) is a target of both the mechanistic target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK), whose role is to facilitate the initiation of autophagy in response to starvation. Upon glucose starvation, dissociation of mTOR from ULK1 and phosphorylation by AMPK leads to the activation of ULK1 activity. Here, we provide evidence that ULK1 is the attachment of O-linked N-acetylglucosamine (O-GlcNAcylated) on the threonine 754 site by O-linked N-acetylglucosamine transferase (OGT) upon glucose starvation. ULK1 O-GlcNAcylation occurs after dephosphorylationof adjacent mTOR-dependent phosphorylation on the serine 757 site by protein phosphatase 1(PP1) and phosphorylation by AMPK. ULK1 O-GlcNAcylation is crucial for binding and phosphorylation ofATG14L, allowing the activation of lipid kinase VPS34 and leading to the production of phosphatidylinositol-(3)-phosphate (PI(3)P), which is required for phagophore formation and initiation of autophagy. Our findings provide insights into the crosstalk between dephosphorylation and O-GlcNAcylation during autophagy and specify a molecular framework for potential therapeutic intervention in autophagy-related diseases.

Inhibition of Unc-51-like Kinase 1 (ULK1) with Novel Small Molecular Inhibitor MRT68921 Preferentially Induces Apoptosis and Autophagy in FLT3-ITD- Mutated Acute Myeloid Leukemia

In normal karyotype acute myeloid leukemia (AML), FLT3-ITD mutation is associated with dismal prognosis with early relapse even after allogeneic stem cell transplantation. Unfortunately, to date small-molecule inhibitors of FLT3 have resulted in only partial and transient clinical responses with residual leukemic blasts acquiring resistance to FLT3 inhibitors. Therefore, elucidation of novel molecular targets should be necessary for effective eradication of FLT3-ITD AML cells. Evidences are accumulating on the functional roles of autophagy in the initiation and maintenance of AML as well as the development of drug resistance. Unc-51-like kinase 1 (ULK1) is a conserved serine-threonine kinase that plays a central role in the initiation of autophagy. Our group demonstrated that ULK1 is potentially involved in the development of resistance of AML leukemia stem cells to BET inhibitor, JQ1. The fact that ULK1 is the only conserved serine/threonine kinase in the autophagy cascade makes it a very attractive target for therapeutic development. However, the role of Ulk1 in FLT3-ITD AML remains unclear. In this study, we observed that MRT68921, a potent inhibitor of both ULK1 and ULK2, induced apoptotic cell death in FLT3-ITD-mutated AML cell lines (MV4-11, Molm13, U937/FLT3-ITD-muated) in a dose-dependent manner. However, apoptosis-inducing effect of MRT68921 was significantly lower in FLT3-WT AML (HL-60, U937). Cell death was accompanied with cleavage of caspases and PARP, which were partially blocked with caspase inhibitor z-VAD-fmk, indicating the caspase-dependent mechanism exists. MRT68921 treatment led to a notable decrease in the levels of phosphorylated (p) ATG13 (Ser 318) as well as total ULK1 and p-ULK1 (Ser 555). Interestingly, MRT68921 induced LC3-II lipidation, autophagosome, and GFP/LC3 punta formation, indicating autophagy was paradoxically activated in FLT3-ITD-mutated AML cells. AMPKa phosphorylation (T712) was increased in MTR68921-responsive cells. In contrast, autophagy induction was negligible to modest in FLT3-WT AML cells. Treatment of FLT3-ITD cells with autophagy inhibitors, 3-MA, bafilomycin A1, and hydroxychloroquine, markedly enhanced the MRT68921-induced apoptosis, strongly suggesting that prosurvival autophagy activation occurred with MRT68921 in FLT3-ITD cells. Reduction in the levels of total FLT3 and p-FLT3 protein were observed concurrently with downregulation of p-STAT5 in FLT3-ITD cells. Endoplasmic reticulum stress-associated proteins, p-PERK and p-eIF2a were also downregulated with MRT68921 in FLT3-ITD cells. Taken together, targeting the ULK1 pathway could be an effective therapeutic strategy for combating FLT3-ITD AML. Inhibition of prosurvival autophagy pathway could enhance the anti-leukemia effects of MRT68921. DisclosuresNo relevant conflicts of interest to declare.

Epidermal growth factor receptor and podocin predict nephropathy progression in type 2 diabetic patients through interaction with the autophagy influencer ULK-1

AimsDiabetic nephropathy (DN) that progress to end stage renal failure is a serious health problem. Autophagy is involved in DN pathogenesis. Finding renal prognostic biomarkers can help in the future renal status prevision. Therefore, the aim of current study was to evaluate and correlate circulating levels of autophagy regulator protein Unc-51-like kinase 1 (ULK-1) with the widely expressed receptor in mammalian kidney; epidermal growth factor receptor (EGFR); and the key functional podocyte protein podocin (PDCN). MethodsSerum levels were assessed by ELISA in 72 type 2 diabetic patients classified according to their urinary albumin/creatinine ratio; 19 normoalbuminuric, 37 microalbuminuric and 16 macroalbuminuric patients; age and sex matched with 18 healthy controls. ResultsMicroalbuminuria and macroalbuminuria patients exhibited decreased ULK-1, EGFR and PDCN levels. Only EGFR showed lower levels in normoalbuminuria compared with controls. ULK-1 and EGFR were significantly higher in normoalbuminuria compared with microalbuminuria and macroalbuminuria patients. ULK-1, EGFR and PDCN were correlated with each other and with some metabolic parameters. ConclusionsULK-1 with EGFR can predict early impairment in DN while PDCN can highlight progressive DN risk EGFR and PDCN may interact synergistically with ULK-1 in autophagy dysregulation as a pathogenic mechanism of DN induction and progression.

MAPK15 is part of the ULK complex and controls its activity to regulate early phases of the autophagic process

Autophagy, a pathway for bulk protein degradation and removal of damaged organelles, represents one of the major responses of cells to stress, thereby exerting a strict control on their correct functioning. Consequently, this process has been involved in the pathogenesis and therapeutic responses of several human diseases. Mitogen-activated protein (MAP) kinase 15 (MAPK15) is an atypical member of the MAP kinase family that recently emerged as a key modulator of autophagy and, through this, of cell transformation. Still, no information is available about signaling pathways mediating the effect of MAPK15 on this process, nor is it known which phase of autophagosome biogenesis is affected by this MAP kinase. Here, we demonstrate that MAPK15 stimulated 5'-AMP-activated protein kinase-dependent activity of UNC-51-like kinase 1 (ULK1), the only protein kinase among the ATG-related proteins, toward downstream substrates and signaling intermediates. Importantly, MAPK15 directly interacted with the ULK1 complex and mediated ULK1 activation induced by starvation, a classical stimulus for the autophagic process. In turn, ULK1 and its highly homologous protein ULK2 are able to transduce MAPK15 signals stimulating early phases of autophagosomal biogenesis in a multikinase cascade that offers numerous potential targets for future therapeutic intervention in cancer and other autophagy-related human diseases.

PKCα replaces AMPK to regulate mitophagy: Another PEDF role on ischaemic cardioprotection.

Both decreased autophagy positive regulator AMP activated protein kinase (AMPK) level and promoted mitophagy are observed in oxygen‐glucose deprivation (OGD) cardiomyocytes treated with pigment epithelium‐derived factor (PEDF). This contradictory phenomenon and its underlying mechanisms have not been thoroughly elucidated. Our previous study reveals that PEDF increases the protein kinase Cα (PKCα) and phospho‐PKCα (p‐PKCα) contents to promote mitophagy. Thus, we investigated the association between PKCα and mitophagy. Here we identify an interaction between PKCα and Unc‐51‐like kinase 1 (ULK1), essential component of mitophagy. Further analyses show this is a direct interaction within a domain of ULK1 that termed the serine/threonine‐rich domain (S/T domain). Notably, a deletion mutant ULK1 that lacks the binding domain is defective in mediating PEDF‐induced mitophagy. Furthermore, we demonstrate that ULK1 is phosphorylated at Ser317/555/777 and Raptor is also phosphorylated by phospho‐PKCα. Phospho‐ULK1 (p‐ULK1) at these sites are all essential for PEDF‐induced mitophagy and reduce the release of mitochondrial ROS and DNA. This study therefore identifies a previously uncharacterized interaction between the ULK1 and PKCα that can replace the AMPK‐dependent mitophagy processes.

Expression of Autophagy Signaling Molecules in the Outer Membranes of Chronic Subdural Hematomas

Chronic subdural hematoma (CSDH) is fundamentally treatable, although it sometimes recurs. We observed, however, several cases of spontaneous resolution of CSDH outer membranes, even in a trabecular type of CSDH, after a trepanation surgical procedure. In this study, we examined the expression of molecules of the autophagy signaling pathway in CSDH outer membranes. Eight patients whose outer membranes were obtained successfully during trepanation were included in this study. By Western blot analysis, we examined the expression of mammalian target of rapamycin (mTOR); GβL; UNC-51-like kinase-1 (ULK1); Beclin-1; autophagy-related genes (Atg) 3, 5, 7, 12, 13, and 16L1β,α; the autophagy marker Light Chain3A/B (LC3A/B); and β-actin, which constitute the autophagy signaling pathway. The expression levels of Beclin-1, Atg12, and LC3A/B were also examined by immunohistochemistry. Almost all of these molecules could be detected in all samples. Beclin-1, Atg12, and LC3A/B were found to be localized in the endothelial cells of vessels and fibroblasts in CSDH. We detected molecules of the autophagy signaling pathway in CSDH outer membranes. Autophagy contributes to the tissue homeostatic process, maintaining cellular integrity by clearing debris. Our data suggest that autophagy might play an important role in the spontaneous resolution of CSDH. Therefore, these molecules may be novel therapeutic targets for the treatment of those with CSDH.

Insulin inhibits autophagy signaling independent of counterregulatory hormone levels but does not affect the effects of exercise.

Acute exercise increases autophagic signaling through Unc-51 like kinase-1 (ULK1) in human skeletal muscle during both anabolic and catabolic conditions. The aim of the present study was to investigate if changes in ULK1 Ser555 phosphorylation during exercise are reflected by changes in phosphorylation of a newly identified ULK1 substrate (ATG14 Ser29) and to elucidate the involvement of circulatory hormones in the regulation of autophagy in human skeletal muscle. We show that 1 h of cycling exercise increases ATG14 Ser29 phosphorylation during both hyperinsulinemic euglycemic and euinsulinemic euglycemic conditions. This could suggest that counterregulatory hormones stimulate autophagy in skeletal muscle, as circulating concentrations of these hormones are highly elevated during exercise. Furthermore, ATG14 Ser29 correlated positively with ULK1 phosphorylation, suggesting that ULK1 Ser555 (activating site) phosphorylation reflects ULK1 kinase activity. In a separate series of experiments, we show that insulin stimulates ULK1 phosphorylation at Ser757 (inhibitory site) in both hypoglycemic and euglycemic conditions, suggesting that counterregulatory hormones (such as epinephrine, norepinephrine, growth hormone, and glucagon) have limited effects on autophagy signaling in human skeletal muscle. In conclusion, 1 h of cycling exercise increases phosphorylation of ATG14 at Ser29 in a pattern that mirrors ULK1 phosphorylation at Ser555. Moreover, insulin effects on autophagy signaling in human skeletal muscle are independent of hypoglycemic and euglycemic conditions.NEW & NOTEWORTHY Autophagy signaling is regulated in a hierarchical order by exercise, insulin, and counterregulatory hormones. Exercise-induced autophagy signaling is stimulated by local factors in skeletal muscle rather than circulatory hormones. Unc-51 like kinase-1 (ULK1) phosphorylation at Ser555 reflects ULK1 kinase activity.

Overexpression of ULK1 Represents a Potential Diagnostic Marker for Clear Cell Renal Carcinoma and the Antitumor Effects of SBI-0206965.

BackgroundUncoordinated 51-like kinase 1 (ULK1) plays a vital role in autophagy. ULK1 dysregulation has recently been found in several human cancers.MethodsmRNA expression levels of ULK1 and clinical information were analysed from The Cancer Genome Atlas data. ULK1 expression levels were verified in 36 paired fresh ccRCC tissue specimens by western blot analysis. Expression of ULK1 was knockdown by shRNA lentivirus. ULK1 activity was inhibited by SBI-0206965. The effect of inhibition of ULK1 was measured by detecting the apoptotic rate, autophagy, and the ratio of ROS and NADPH. The efficacy of SBI-0206965 in vivo was assessed by the murine xenograft model.FindingsULK1 mRNA expression was significantly upregulated in clear cell renal cell carcinoma (ccRCC) and overexpression of ULK1 correlated with poor outcomes. We found that ULK1 was highly expressed in 66.7% of ccRCC tumours (p < 0·05). Knockdown of ULK1 and selective inhibition of ULK1 by SBI-0206965 induced cell apoptosis in ccRCC cells. We demonstrated that SBI-0206965 triggered apoptosis by preventing autophagy and pentose phosphate pathway (PPP) flux. Furthermore, blocking the kinase activity of ULK1 with SBI-0206965 resulted in a level of anticancer effect in vivo.InterpretationTaken together, our results suggested that ULK1 was upregulated in ccRCC tumours and may be a potential therapeutic target. Therefore, SBI-0206965 should be further considered as an anti-ccRCC agent.FundThis work was supported in part by The National Natural Science Foundation of China (No. 81570748) and Natural Science Foundation of Fujian Province (No. 2018J01345, 2017XQ1194).