Autophagy activator promotes neuronal differentiation of adult adipose-derived stromal cells

Preliminary research from our group found altered autophagy intensity during adipose-derived stromal cell differentiation into neuronal-like cells, and that this change was associated with morphological changes in differentiated cells. This study aimed to verify the role of rapamycin, an autophagy activator, in the process of adipose-derived stromal cell differentiation into neuronal-like cells. Immunohistochemical staining showed that expression of neuron-specific enolase and neurofilament-200 were gradually upregulated in adipose-derived stromal cells after 5 mM 13-mercaptoethanol induction, and the differentiation rate gradually increased with induction time. Using transmission electron microscopy, induced cells were shown to exhibit cytoplasmic autophagosomes, with bilayer membranes, and autolysosomes. After rapamycin （200 IJg/L） induction for 1 hour, adipose-derived stromal cells began to extend long processes, similar to the morphology of neuronal-like cells, while untreated cells did not exhibit similar morphologies until 3 hours after induction. Moreover, the differentiation rate was significantly increased after rapamycin treatment. Compared with untreated cells, expression of LC3, an autophagy protein, was also significantly upregulated. Positive LC3 expression tended to concentrate at cell nuclei with increasing induction times. Our experimental findings indicate that autophagy can significantly increase the speed of adipose-derived stromal cell differentiation into neuronal-like cells.

Atorvastatin activates autophagy and promotes neurological function recovery after spinal cord injury

Atorvastatin, a lipid-lowering medication, provides neuroprotective effects, although the precise mechanisms of action remain unclear. Our previous studies confirmed activated autophagy following spinal cord injury, which was conducive to recovery of neurological functions. We hypothesized that atorvastatin could also activate autophagy after spinal cord injury, and subsequently improve recovery of neurological functions. A rat model of spinal cord injury was established based on the Allen method. Atorvastatin（5 mg/kg） was intraperitoneally injected at 1 and 2 days after spinal cord injury. At 7 days post-injury, western blot assay, reverse transcription-polymerase chain reaction, and terminal deoxynucleotidyl transferase-mediated dU TP nick-end labeling（TUNEL） staining results showed increased Beclin-1 and light chain 3B gene and protein expressions in the spinal cord injury ＋ atorvastatin group. Additionally, caspase-9 and caspase-3 expression was decreased, and the number of TUNEL-positive cells was reduced. Compared with the spinal cord injury ＋ saline group, Basso, Beattie, and Bresnahan locomotor rating scale scores significantly increased in the spinal cord injury ＋ atorvastatin group at 14–42 days post-injury. These findings suggest that atorvastatin activated autophagy after spinal cord injury, inhibited apoptosis, and promoted recovery of neurological function.

MiR-3653 blocks autophagy to inhibit epithelial-mesenchymal transition in breast cancer cells by targeting the autophagy-regulatory genes ATG12 and AMBRA1

Background:Metastasis is the main cause of tumor-associated death and mainly responsible for treatment failure of breast cancer.Autophagy accelerates tumor metastasis.In our work,we aimed to investigate the possibility of microRNAs(miRNAs)which participate in the regulation of autophagy to inhibit tumor metastasis.Methods:MiRNA array and comprehensive analysis were performed to identify miRNAs which participated in the regulation of autophagy to inhibit tumor metastasis.The expression levels of miR-3653 in breast cancer tissues and cells were detected by quantitative real-time polymerase chain reaction.In vivo and in vitro assays were conducted to determine the function of miR-3653.The target genes of miR-3653 were detected by a dual luciferase reporter activity assay and Western blot.The relationship between miR-3653 and epithelial-mesenchymal transition(EMT)was assessed by Western blot.Student’s t-test was used to analyze the difference between any two groups,and the difference among multiple groups was analyzed with one-way analysis of variance and a Bonferroni post hoc test.Results:miR-3653 was downregulated in breast cancer cells with high metastatic ability,and high expression of miR-3653 blocked autophagic flux in breast cancer cells.Clinically,low expression of miR-3653 in breast cancer tissues(0.054±0.013 vs.0.131±0.028,t=2.475,P=0.014)was positively correlated with lymph node metastasis(0.015±0.004 vs.0.078±0.020,t=2.319,P=0.023)and poor prognosis(P<0.001).miR-3653 ameliorated the malignant phenotypes of breast cancer cells,including proliferation,migration(MDA-MB-231:0.353±0.013 vs.1.000±0.038,t=16.290,P<0.001;MDA-MB-468:0.200±0.014 vs.1.000±0.043,t=17.530,P<0.001),invasion(MDA-MB-231:0.723±0.056 vs.1.000±0.035,t=4.223,P=0.013;MDA-MB-468:0.222±0.016 vs.1.000±0.019,t=31.050,P<0.001),and colony formation(MDA-MB-231:0.472±0.022 vs.1.000±0.022,t=16.620,P<0.001;MDA-MB-468:0.650±0.040 vs.1.000±0.098,t=3.297,P=0.030).The autophagy-associated genes autophagy-related gene 12(ATG12)and activating molecule in beclin 1-regulated autophagy protein 1(AMBRA1)are target genes of miR-3653.Further studies showed that miR-3653 inhibited EMT by targeting ATG12 and AMBRA1.Conclusions:Our findings suggested that miR-3653 inhibits the autophagy process by targeting ATG12 and AMBRA1,thereby inhibiting EMT,and provided a new idea and target for the metastasis of breast cancer.

A molecular link between autophagy and circadian rhythm in plants

Extremely high or low autophagy levels disrupt plant survival under nutrient starvation.Recently,autophagy has been reported to display rhythms in animals.However,the mechanism of circadian regulation of autophagy is still unclear.Here,we observed that autophagy has a robust rhythm and that various autophagy-related genes(ATGs)are rhythmically expressed in Arabidopsis.Chromatin immunoprecipitation(Ch IP)and dual-luciferase(LUC)analyses showed that the core oscillator gene TIMING OF CAB EXPRESSION 1(TOC1)directly binds to the promoters of ATG(ATG1 a,ATG2,and ATG8 d)and negatively regulates autophagy activities under nutritional stress.Furthermore,autophagy defects might affect endogenous rhythms by reducing the rhythm amplitude of TOC1 and shortening the rhythm period of CIRCADIAN CLOCK-ASSOCIATED 1(CCA1).Autophagy is essential for the circadian clock pattern in seedling development and plant sensitivity to nutritional deficiencies.Taken together,our studies reveal a plant strategy in which the TOC1-ATG axis involved in autophagy-rhythm crosstalk to fine-tune the intensity of autophagy.

A NOVEL DIRECT ACTIVATOR OF TFEB PROMOTES AUTOPHAGY AND LYSOSOME BIOGENESIS AND PROTECTS NEURONS IN THE BRAIN

Autophagy dysfunction is a common feature in neurodegenerative disorders caused by the accumulation of toxic,aggregate-prone proteins.Increasing evidence have demonstrated that genetic or pharmacological activation of transcription factor EB(TFEB),a master regulator of autophagy and lysosomal biogenesis,ameliorates neurotoxicity and rescues neurodegenerative phenotypes in several animal models of neurodegenerative diseases.