miR-34a mediates oxaliplatin resistance of colorectal cancer cells by inhibiting macroautophagy via transforming growth factor-β/Smad4 pathway

To investigate whether microRNA (miR)-34a mediates oxaliplatin (OXA) resistance of colorectal cancer (CRC) cells by inhibiting macroautophagy via the transforming growth factor (TGF)-β/Smad4 pathway.METHODSmiR-34a expression levels were detected in CRC tissues and CRC cell lines by quantitative real-time polymerase chain reaction. Computational search, functional luciferase assay and western blotting were used to demonstrate the downstream target of miR-34a in CRC cells. Cell viability was measured with Cell Counting Kit-8. Apoptosis and macroautophagy of CRC cells were analyzed by flow cytometry and transmission electron microscopy, and expression of beclin I and LC3-II was detected by western blotting.RESULTSExpression of miR-34a was significantly reduced while expression of TGF-β and Smad4 was increased in CRC patients treated with OXA-based chemotherapy. OXA treatment also resulted in decreased miR-34a levels and increased TGF-β and Smad4 levels in both parental cells and the OXA-resistant CRC cells. Activation of macroautophagy contributed to OXA resistance in CRC cells. Expression levels of Smad4 and miR-34a in CRC patients had a significant inverse correlation and overexpressing miR-34a inhibited macroautophagy activation by directly targeting Smad4 through the TGF-β/Smad4 pathway. OXA-induced downregulation of miR-34a and increased drug resistance by activating macroautophagy in CRC cells.CONCLUSIONmiR-34a mediates OXA resistance of CRC by inhibiting macroautophagy via the TGF-β/Smad4 pathway.

Structural biology of the macroautophagy machinery

Macroautophagy is a conserved degradative process mediated through formation of a unique double- membrane structure, the autophagosome. The discovery of autophagy-related （Atg） genes required for autophagosome formation has led to the characterization of approximately 20 genes mediating this process. Recent structural studies of the Atg proteins have provided the molecular basis for their function. Here we summarize the recent progress in elucidating the structural basis for autophagosome formation.

Macroautophagy in sporadic and the genetic form of Parkinson’s disease with the A53T asynuclein mutation

Background:The A53T mutation in the a-synuclein gene causes autosomal-dominant Lewy body Parkinson’s disease(PD).Cultured cell models have linked this mutation to increased cell macroautophagy,although evidence of enhanced macroautophagy in patients with this mutation has not been assessed.Objective:To determine whether macroautophagy is increased by the A53T a-synuclein gene mutation in PD patients and cell models.Methods:Formalin-fixed paraffin-embedded 10μm-thick tissue sections from the substantia nigra and anterior cingulate cortex of two PD patients with the A53T a-synuclein gene mutation were compared with four sporadic PD cases and four controls obtained from the Sydney Brain Bank.Lewy bodies were isolated from frontal cortex of a case with late stage PD(recruited from South Australian Brain Bank).Immunohistochemistry was performed for a-synuclein and the macroautophagy markers autophagy-specific gene(ATG)5,ATG6/Beclin1 and ATG8/LC3.SHSY5Y cells were transfected with wild type or A53T mutant a-synuclein plasmids and observable changes in macroautophagy marker protein levels assessed using Western blotting.Results:a-Synuclein immunoreactive neurites and dots were more numerous in patients with A53T mutations compared with late stage sporadic PD patients,and perinuclear cytoplasmic a-synuclein aggregates were observed in the a-synuclein A53T gene transfected SH-SY5Y cells compared to wild type transfections.All PD patients(with or without A53T mutations)had increased immunohistochemical evidence for macroautophagy compared with controls,and the levels of the ATG5 complex were equally increased in wild type and A53T a-synuclein gene transfected cells compared to controls.Conclusion:Despite increased a-synuclein accumulation with A53T mutations,macroautophagy is not increased above that observed in sporadic patients with PD or in cells transfected with wild type a-synuclein,suggesting that mutated a-synuclein protein is not removed by macroautophagy.

Autophagy and inflammation in ischemic stroke

Appropriate autophagy has protective effects on ischemic nerve tissue,while excessive autophagy may cause cell death.The inflammatory response plays an important role in the survival of nerve cells and the recovery of neural tissue after ischemia.Many studies have found an interaction between autophagy and inflammation in the pathogenesis of ischemic stroke.This study outlines recent advances regarding the role of autophagy in the post-stroke inflammatory response as follows.(1)Autophagy inhibits inflammatory responses caused by ischemic stimulation through mTOR,the AMPK pathway,and inhibition of inflammasome activation.(2)Activation of inflammation triggers the formation of autophagosomes,and the upregulation of autophagy levels is marked by a significant increase in the autophagy-forming markers LC3-II and Beclin-1.Lipopolysaccharide stimulates microglia and inhibits ULK1 activity by direct phosphorylation of p38 MAPK,reducing the flux and autophagy level,thereby inducing inflammatory activity.(3)By blocking the activation of autophagy,the activation of inflammasomes can alleviate cerebral ischemic injury.Autophagy can also regulate the phenotypic alternation of microglia through the nuclear factor-κB pathway,which is beneficial to the recovery of neural tissue after ischemia.Studies have shown that some drugs such as resveratrol can exert neuroprotective effects by regulating the autophagy-inflammatory pathway.These studies suggest that the autophagy-inflammatory pathway may provide a new direction for the treatment of ischemic stroke.

Herbal cake-partitioned moxibustion inhibits colonic autophagy in Crohn’s disease via signaling involving distinct classes of phosphatidylinositol 3-kinases

BACKGROUND Autophagy is an evolutionarily conserved biological process in eukaryotic cells that involves lysosomal-mediated degradation and recycling of related cellular components.Recent studies have shown that autophagy plays an important role in the pathogenesis of Crohn’s disease(CD).Herbal cake-partitioned moxibustion(HM)has been historically practiced to treat CD.However,the mechanism by which HM regulates colonic autophagy in CD remains unclear.AIM To observe whether HM can alleviate CD by regulating colonic autophagy and to elucidate the underlying mechanism.METHODS Rats were randomly divided into a normal control(NC)group,a CD group,an HM group,an insulin+CD(I+CD)group,an insulin+HM(I+HM)group,a rapamycin+CD(RA+CD)group,and a rapamycin+HM(RA+HM)group.2,4,6-trinitrobenzenesulfonic acid was administered to establish a CD model.The morphology of the colonic mucosa was observed by hematoxylin-eosin staining,and the formation of autophagosomes was observed by electron microscopy.The expression of autophagy marker microtubule-associated protein 1 light chain 3 beta(LC3B)was observed by immunofluorescence staining.Insulin and rapamycin were used to inhibit and activate colonic autophagy,respectively.The mRNA expression levels of phosphatidylinositol 3-kinase class I(PI3KC1),Akt1,LC3B,sequestosome 1(p62),and mammalian target of rapamycin(mTOR)were evaluated by RT-qPCR.The protein expression levels of interleukin 18(IL-18),tumor necrosis factor-α(TNF-α),nuclear factorκB/p65(NF-κB p65),LC3B,p62,coiled-coil myosin-like BCL2-interacting protein(Beclin-1),p-mTOR,PI3KC1,class III phosphatidylinositol 3-kinase(PI3KC3/Vps34),and p-Akt were evaluated by Western blot analysis.RESULTS Compared with the NC group,the CD group showed severe damage to colon tissues and higher expression levels of IL-18 and NF-κB p65 in colon tissues(P<0.01 for both).Compared with the CD group,the HM group showed significantly lower levels of these proteins(PIL-18<0.01 and Pp65<0.05).There were no significant differences in the expression of TNF-αprotein in colon tissue among the rat groups.Typical autophagic vesicles were found in both the CD and HM groups.The expression of the autophagy proteins LC3B and Beclin-1 was upregulated(P<0.01 for both)in the colon tissues of rats in the CD group compared with the NC group,while the protein expression of p62 and p-mTOR was downregulated(P<0.01 for both).However,these expression trends were significantly reversed in the HM group compared with the CD group(PLC3B<0.01,PBeclin-1<0.05,Pp62<0.05,and Pm-TOR<0.05).Compared with those in the RA+CD group,the mRNA expression levels of PI3KC1,Akt1,mTOR,and p62 in the RA+HM group were significantly higher(PPI3KC1<0.01 and PAkt1,mTOR,and p62<0.05),while those of LC3B were significantly lower(P<0.05).Compared with the RA+CD group,the RA+HM group exhibited significantly higher PI3KC1,p-Akt1,and pmTOR protein levels(PPI3KC1<0.01,Pp-Akt1<0.05,and Pp-mTOR<0.01),a higher p62 protein level(P=0.057),and significantly lower LC3B and Vps34 protein levels(P<0.01 for both)in colon tissue.CONCLUSION HM can activate PI3KC1/Akt1/mTOR signaling while inhibiting the PI3KC3(Vps34)-Beclin-1 protein complex in the colon tissues of CD rats,thereby inhibiting overactivated autophagy and thus exerting a therapeutic effect.

Mitochondrial dysfunction and mitophagy:crucial players in burn trauma and wound healing

Burn injuries are a significant cause of death worldwide,leading to systemic inflammation,multiple organ failure and sepsis.The progression of burn injury is explicitly correlated with mitochondrial homeostasis,which is disrupted by the hyperinflammation induced by burn injury,leading to mitochondrial dysfunction and cell death.Mitophagy plays a crucial role in maintaining cellular homeostasis by selectively removing damaged mitochondria.A growing body of evidence from various disease models suggest that pharmacological interventions targeting mitophagy could be a promising therapeutic strategy.Recent studies have shown that mitophagy plays a crucial role in wound healing and burn injury.Furthermore,chemicals targeting mitophagy have also been shown to improve wound recovery,highlighting the potential for novel therapeutic strategies based on an in-depth exploration of the molecular mechanisms regulating mitophagy and its association with skin wound healing.

Dihydromyricetin and Salvianolic acid B inhibit alpha-synuclein aggregation and enhance chaperone-mediated autophagy

Background:Progressive accumulation ofα-synuclein is a key step in the pathological development of Parkinson’s disease.Impaired protein degradation and increased levels ofα-synuclein may trigger a pathological aggregation in vitro and in vivo.The chaperone-mediated autophagy(CMA)pathway is involved in the intracellular degradation processes ofα-synuclein.Dysfunction of the CMA pathway impairsα-synuclein degradation and causes cytotoxicity.Results:In the present study,we investigated the effects on the CMA pathway andα-synuclein aggregation using bioactive ingredients(Dihydromyricetin(DHM)and Salvianolic acid B(Sal B))extracted from natural medicinal plants.In both cell-free and cellular models ofα-synuclein aggregation,after administration of DHM and Sal B,we observed significant inhibition ofα-synuclein accumulation and aggregation.Cells were co-transfected with a Cterminal modifiedα-synuclein(SynT)and synphilin-1,and then treated with DHM(10μM)and Sal B(50μM)16 hours after transfection;levels ofα-synuclein aggregation decreased significantly(68%for DHM and 75%for Sal B).Concomitantly,we detected increased levels of LAMP-1(a marker of lysosomal homeostasis)and LAMP-2A(a key marker of CMA).Immunofluorescence analyses showed increased colocalization between LAMP-1 and LAMP-2A withα-synuclein inclusions after treatment with DHM and Sal B.We also found increased levels of LAMP-1 and LAMP-2A both in vitro and in vivo,along with decreased levels ofα-synuclein.Moreover,DHM and Sal B treatments exhibited anti-inflammatory activities,preventing astroglia-and microglia-mediated neuroinflammation in BAC-α-syn-GFP transgenic mice.Conclusions:Our data indicate that DHM and Sal B are effective in modulatingα-synuclein accumulation and aggregate formation and augmenting activation of CMA,holding potential for the treatment of Parkinson’s disease.

Dysregulation of autophagy and mitochondrial function in Parkinson’s disease

Parkinson’s disease(PD)is the second most common neurodegenerative disease.Increasing evidence supports that dysregulation of autophagy and mitochondrial function are closely related with PD pathogenesis.In this review,we briefly summarized autophagy pathway,which consists of macroautophagy,microautophagy and chaperone-mediated autophagy(CMA).Then,we discussed the involvement of mitochondrial dysfunction in PD pathogenesis.We specifically reviewed the recent developments in the relationship among several PD related genes,autophagy and mitochondrial dysfunction,followed by the therapeutic implications of these pathways.In conclusion,we propose that autophagy activity and mitochondrial homeostasis are of high importance in the pathogenesis of PD.Better understanding of these pathways can shed light on the novel therapeutic methods for PD prevention and amelioration.

Adaptive immunity at the crossroads of autophagy and metabolism

The function of lymphocytes is dependent on their plasticity,particularly their adaptation to energy availability and environmental stress,and their protein synthesis machinery.Lymphocytes are constantly under metabolic stress,and macroautophagy/autophagy is the primary metabolic pathway that helps cells overcome stressors.The intrinsic role of autophagy in regulating the metabolism of adaptive immune cells has recently gained increasing attention.In this review,we summarize and discuss the versatile roles of autophagy in regulating cellular metabolism and the implications of autophagy for immune cell function and fate,especially for T and B lymphocytes.

Autophagy-lysosome pathway as a source of candidate biomarkers for Parkinson's disease

Parkinson's disease(PD)is a neurodegenerative disorder characterized by progressive motor disturbances and affects more than 1%of the worldwide population.Diagnosis of PD relies on clinical history and physical examination,but misdiagnosis is common in early stages.Despite considerable progress in understanding PD pathophysiology,including genetic and biochemical causes,diagnostic approaches lack accuracy and interventions are restricted to symptomatic treatments.Identification of biomarkers for PD may allow early and more precise diagnosis and monitoring of dopamine replacement strategies and disease-modifying treatments.Increasing evidence suggests that autophagic dysregulation causes the accumulation of abnormal proteins,such as aberrantα-synuclein,a protein critical to PD pathogenesis.Mutations in the GBA gene are a major PD risk factor andβ-glucocerebrosidase(GCase)is also emerging as an important molecule in PD pathogenesis.Consequently,proteins involved in the autophagy-lysosome pathway and GCase protein levels and activity are prime targets for the research and development of new PD biomarkers.The studies so far in PD biological material have yielded some consistent results,particularly regarding the levels of Hsc70,a component of the chaperone-mediated autophagy pathway,and the enzymatic activity of GCase in GBA mutation carriers.In the future,larger longitudinal studies,corroborating previous research on possible biomarker candidates,as well as extending the search for possible candidates for other lysosomal components,may yield more definitive results.