Autophagy functions on EMT in gastrulation of avian embryo

Abstract

y These authors contributed equally to this work.Keywords: autophagy, Atg7, EMT and chick embryo, gastrulation Abbreviations: 3-MA, 3-Methyladenine; BF, bright-field; DAPI, 49-6-Diamidino-2-phenylindole; EB, embryoid bodies; E-Cad, E-cadherin; EMTs, epithelial-mesenchymal transitions; GFP, green fluorescent protein; HN, Hensen's node; MAPILC3(LC3), microtubule-associated protein 1 light chain 3; mTOR, mammalian target of rapamycin; N-Cad, N-cadherin; NT, neural tube; PBS, phosphate-buffered saline; PCD, Programmed cell death; PD, idiopathic Parkinson's Disease; PI3K, phosphoinositide-3-kinase; PPIA, peptidylprolyl isomerase A; PS, primitive streak; RAPA, Rapamycin; RT-PCR, reverse transcription PCR; shh, sonic hedgehog.Autophagy is important for cell renewing for its contribution to the degradation of bulk cytoplasm, long-lived proteins, and entire organelles and its role in embryonic development is largely unknown. In our study, we investigated the function of autophagy in gastrulation of the chick embryo using both in vivo and in vitro approaches, especially in the EMT process, and we found that autophagy gene Atg7 was expressed on the apical side of the ectoderm and endoderm. Over-expression of Atg7 could enhance the expression of Atg8 and the E-cadherin, the latter of which is a crucial marker of the EMT process. We also found that the disturbance of autophagy could retard the development of chick embryos in HH4 with shorter primitive steak than that in the control group, which is a newly formed structure during EMT process. So we assumed that autophagy could affect EMT process by adhesion molecule expression. Moreover, more molecules, such as slug, chordin, shh et., which were all involved in EMT process, were detected to address the mechanism of this phenomena. We established that the inhibition of autophagy could cause developmental delay by affecting EMT process in gastrulation of chick embryos.

The impact of autophagy on the development of senescence in primary tubular epithelial cells

“…43,44 On the other hand, an anti-EMT role of autophagy sustaining the epithelial phenotype has been described in hepatocytes and in different organs during embryogenesis. 45,46 We found reduced signs of epithelial dedifferentiation in post-ischemic kidneys when Atg5 was conditionally ablated from proximal tubular S3 segments. 21 The kidneys also developed less post-injurious senescence arguing for a potential link between epithelial phenotypical maintenance, autophagy and senescence.…”

Proper autophagy is indispensable for angiogenesis during chick embryo development

“…12 One of the other ways to promote autophagy is by inducing ER stress such as Tunicamycin, which is a glycosylation inhibitor. Another frequently-used pharmacological compound in autophagy study is 3-MA, 13,14 which blocks the formation of LC3-II and p62 degradation, so that it could inhibit ATG5-induced autophagy.…”

Dissecting pharmacological effects of chloroquine in cancer treatment: interference with inflammatory signaling pathways

“…74 For instance, fasting induces transcription factor EB (TFEB) which activates mitochondrial and lysosomal biogenesis, and enables autophagy, to allow removal and replacement of damaged organelles. 80 Consistently, developmental delay has been observed in chick embryos when autophagy was inhibited. 75 Drugs that interfere with the activation of TFEB, such as anthracyclines, impair autophagy and cause cardiomyopathy.…”

“…TFEB protects the heart from cardiac injury during ischemia-reperfusion, which would otherwise cause cell death by hypoxia-reoxygenation. 80 76 The interference of anthracyclines with TFEB activity can also impair autophagy of peroxisomes, pexophagy, which may contribute to neurotoxicity, cognitive dysfunction, and accelerated brain aging in cancer patients and survivors.…”