ABSTRACT: The intestinal epithelium is continuously renewed by a pool of intestinal stem cells expressing Lgr5. We show that deletion of the key autophagy gene Atg7 affects the survival of Lgr5+ intestinal stem cells. Mechanistically, this involves defective DNA repair, oxidative stress, and altered interactions with the microbiota. This study highlights the importance of autophagy in maintaining the integrity of intestinal stem cells.
Project description:To understand the changes in gene expression in autophagy-deficient cells after the exposure to endogenous or exogenous replication stress, we carried out whole-genome microarray expression profiling of untreated and aphidicolin-treated ATG7-/- HEK293 cells.
Project description:Emergency myelopoiesis (EM) is critical for immune defense against pathogens, which requires rapid replenishing of mature myeloid cells. The EM process involves a rapid cell cycle switch from the quiescent hematopoietic stem cells (HSCs) to highly proliferative myeloid progenitors (MPs). How this cell cycle switch is regulated remains poorly understood. Here, we reveal that ATG7, a critical autophagy factor is essential for the rapid proliferation of MPs during human myelopoiesis. Peripheral blood (PB) mobilized HSPCs with ATG7 knock-down or HSPCs derived from ATG7-/- human embryonic stem cells (hESCs) exhibit severe defect in proliferation at MP stage during myeloid/granulocytes differentiation. ATG7 deficient MPs show substantially elevated P53 protein and up-regulation of P53 signaling pathway genes. Mechanistically, ATG7 dependent autophagy mediates P53 degradation in lysosome that allows normal proliferation of MPs. Together, we reveal an essential role of autophagy for P53 degradation in cell cycle switch during human myelopoiesis
Project description:Regulatory T (Treg) cells respond to immune and inflammatory signals to mediate immunosuppression, but how the functional integrity of Treg cells is maintained under activating environments is unclear. Here we show that autophagy is active in Treg cells and supports their lineage stability and survival fitness. Treg cell–specific deletion of Atg7 or Atg5, both essential genes in autophagy, leads to loss of Treg cells, greater tumor resistance and development of inflammatory disorders. Atg7-deficient Treg cells show increased apoptosis and readily lose expression of the transcription factor Foxp3, especially after activation. Mechanistically, autophagy deficiency upregulates mTORC1 and c-Myc and glycolytic metabolism, which contributes to defective Treg function. Therefore, autophagy couples environmental signals and metabolic homeostasis to protect lineage and survival integrity of Treg cells in activating contexts.
Project description:This study examined the effects of genetic knockdown of autophagy genes on vertebrate cardiac development We performed microarray studies comparing the hearts of control zebrafish embryos to the hearts of embryos with decreased expression of the autophagy genes atg5, becn1 or atg7. The results provide insight into the role of autophagy in developmental morphogenesis. Hearts were purified from 3 day-old zebrafish embryos injected with control or autophagy gene-specific morpholino oligonucleotides. RNA was prepared from all samples and hybridized to zebrafish-specific Affymetricx arrays.
Project description:To investigate the role of motor neuron autophagy in ALS, we generated mice in which the critical autophagy gene Atg7 was specifically disrupted in motor neurons (Atg7 cKO). We also bred these mice to the SOD1G93A mouse model of ALS. Then we performed RNA sequencing on lumbar spinal cords from these mice to determine how motor neuron autophagy inhibition altered gene expression.
Project description:Autophagy is a mechanism that regulates cellular metabolism and clearance of damaged macromolecules and organelles. Impaired degradation of modified macromolecules contributes to cellular dysfunction and is observed in aged tissue and senescent cells. We have inactivated Atg7, an essential autophagy gene, in murine keratinocytes and have found in an earlier study that this resulted in increased baseline oxidative stress and reduced capacity to degrade crosslinked proteins after oxidative ultraviolet stress. To investigate whether autophagy deficiency would promote cellular aging, we studied, how Atg7 deficient (KO) and Atg7 bearing cells (WT) would respond to stress induced by Paraquat (PQ), an oxidant drug commonly used to induce cellular senescence.
Project description:To determine the role of autophagy in the maintenance of genome stability and nucleic acid metabolism, the chromatin-bound proteins in autophagy-deficient ATG7-/- HEK293 cells were compared with autophagy-proficient ATG7+/+ HEK293 cells by Data-independent acquisition mass spectrometry (DIA-MS).
Project description:The intestinal epithelium is continuously regenerated by highly proliferative Lgr5+ intestinal stem cells (ISCs). The existence of a population of quiescent ISCs has been suggested yet its identity and features remain controversial. Here we describe that the expression of the RNA-binding protein Mex3a labels a subpopulation of Lgr5+ cells that divide less frequently and contribute to regenerate all intestinal lineages with slow kinetics. Single cell transcriptomic analysis revealed two classes of Lgr5-high cells, one of them defined by the Mex3a-expression program and by low levels of proliferation genes. Lineage tracing experiments show that large fraction of Mex3a+ cell population is continuously recalled into the rapidly dividing self-renewing ISC pool in homeostatic conditions. Chemotherapy and radiation target preferentially rapidly dividing Lgr5+ cells but spare the Mex3a-high/Lgr5+ population, which helps sustain the renewal of the intestinal epithelium during treatment.
Project description:Expression array analysis of mice livers with conditional deletion of autophagy related protein 7 (Atg7). Whole RNA from mice livers of 2 month old control (Atg7 FF), Olig1-CRE:Atg7 FF (conditional deletion in hepatocytes) and Alb-CRE:Atg7 FF (conditional deletion in hepatocytes/cholangiocytes) were analyzed. The results provide insight into the gene expression profile and role of autophagy in hepatocytes or hepatocytes/cholangiocytes in hepatic growth regulation and hepatocarcinogenesis.