GADD45A inhibits autophagy by regulating the interaction between BECN1 and PIK3C3

Abstract

Abbreviations: ACTB/b-actin, actin, beta; ATG, autophagy-related, Baf, bafilomycin A 1 ; BECN1, Beclin 1, autophagy related; DAPI, 4 0 ,6-diamidino-2-phenylindol dihydrochloride; DNA, deoxyribose nucleic acid; GADD45A, growth arrest and DNA-damage-inducible, alpha; GFP, green fluorescent protein; GST, glutathione s-transferase; LC3/MAP1LC3, microtubule-associated protein 1 light chain 3; MEFs, mouse embryonic fibroblasts; MTOR, mechanistic target of rapamycin (serine/threonine kinase); PIK3C3, phosphatidylinositol 3-kinase, catalytic subunit type 3; RFP, red fluorescent protein; SDS, sodium dodecyl sulfate; SQSTM1, sequestosome 1; UVR, ultraviolet radiation GADD45A is a TP53-regulated and DNA damage-inducible tumor suppressor protein, which regulates cell cycle arrest, apoptosis, and DNA repair, and inhibits tumor growth and angiogenesis. However, the function of GADD45A in autophagy remains unknown. In this report, we demonstrate that GADD45A plays an important role in regulating the process of autophagy. GADD45A is able to decrease LC3-II expression and numbers of autophagosomes in mouse tissues and different cancer cell lines. Using bafilomycin A 1 treatment, we have observed that GADD45A regulates autophagosome initiation. Likely, GADD45A inhibition of autophagy is through its influence on the interaction between BECN1 and PIK3C3. Immunoprecipitation and GST affinity isolation assays exhibit that GADD45A directly interacts with BECN1, and in turn dissociates the BECN1-PIK3C3 complex. Furthermore, we have mapped the 71 to 81 amino acids of the GADD45A protein that are necessary for the GADD45A interaction with BECN1. Knockdown of BECN1 can abolish autophagy alterations induced by GADD45A. Taken together, these findings provide the novel evidence that GADD45A inhibits autophagy via impairing the BECN1-PIK3C3 complex formation.

The inhibition of apoptosis through myocardial postconditioning by affecting Fas/FasIg signaling through miR139‐3p and miR181a‐1

“…LC3‐II expression is increased in Gadd45a‐knockout cells but is decreased in cells that overexpress Gadd45a. It was also reported that Gadd45a can disrupt the formation of Becn1 and the phosphatidylinositol 3‐kinase complex that is required for the initiation of autophagy 34 . Another study showed that the mRNA levels of Gadd45a expression were increased while protein levels were decreased in diabetic hearts 47 .…”

“…ROS are generally considered to be one of the main inductors of autophagy, which is activated to reduce oxidative stress 33 . Becn1, a gene required to initiate the formation of autophagosome in autophagy, 34 contributes to cellular homeostasis by regulating autophagy, also participating in the classification of vacuolar proteins and apoptosis. Besides this, it plays a protective role against neurodegenerative and cardiac diseases 35 .…”

“…It was also reported that Gadd45a can disrupt the formation of Becn1 and the phosphatidylinositol 3-kinase complex that is required for the initiation of autophagy. 34 Another study showed that the mRNA levels of Gadd45a expression were increased while protein levels were decreased in diabetic hearts. 47 Selenite therapy suppressed Gadd45a expression significantly in Keshan disease, which is a fatal form of cardiomyopathy, while expression was increased in the presence of a selenium deficiency.…”

Compound porcine cerebroside and ganglioside injection attenuates cerebral ischemia–reperfusion injury in rats by targeting multiple cellular processes

“…CPCGI also suppressed the expression of GADD45α, a protein that has been shown to activate apoptosis by inducing the translocation of BCL2L11/Bim from the cytoskeleton to the mitochondria 41. Interestingly, GADD45α has also been shown to inhibit autophagy by directly interacting with Beclin1,42 suggesting that CPCGI might induce autophagy as a protective mechanism in the ischemic cortex. The results were in accordance with our previous data.…”

Potent USP10/13 antagonist spautin‐1 suppresses melanoma growth via ROS‐mediated DNA damage and exhibits synergy with cisplatin

“…As such GADD45A and GADD45B were significantly increased after spautin‐1 treatment. These two proteins were targets of DNA damage, and they played critical roles in apoptosis and G2/M checkpoint in response to DNA damage . In addition, BTG2, a cell cycle control gene, initiated the G2/M phase arrest and inhibited cell growth and was induced in response to DNA damage mediated by p53‐dependent mechanisms .…”