Role of Atg5-dependent cell death in the embryonic development of Bax/Bak double-knockout mice

Abstract

Programmed cell death, which is required for the development and homeostasis of metazoans, includes mechanisms such as apoptosis, autophagic cell death, and necrotic (or type III) death. Members of the Bcl2 family regulate apoptosis, among which Bax and Bak act as a mitochondrial gateway. Although embryonic fibroblasts from Bax/Bak double-knockout (DKO) mice are resistant to apoptosis, we previously demonstrated that these cells die through an autophagy-dependent mechanism in response to various types of cellular stressors. To determine the physiological role of autophagy-dependent cell death, we generated Atg5/Bax/Bak triple-knockout (TKO) mice, in which autophagy is greatly suppressed compared with DKO mice. Embryonic fibroblasts and thymocytes from TKO mice underwent autophagy much less frequently, and their viability was much higher than DKO cells in the presence of certain cellular stressors, providing genetic evidence that DKO cells undergo Atg5-dependent death. Compared with wild-type embryos, the loss of interdigital webs was significantly delayed in DKO embryos and was even further delayed in TKO embryos. Brain malformation is a distinct feature observed in DKO embryos on the 129 genetic background, but not in those on a B6 background, whereas such malformations appeared in TKO embryos even on a B6 background. Taken together, our data suggest that Atg5-dependent cell death contributes to the embryonic development of DKO mice, implying that autophagy compensates for the deficiency in apoptosis.

Dpp regulates autophagy-dependent midgut removal and signals to block ecdysone production

“…1a). This dramatic cell death was also observed in cell clones homozygous for tkv [5] (Fig. 1a), thus demonstrating an essential role for Dpp signaling in survival of midgut cells.…”

“…The following stocks were from the Bloomington Drosophila Stock Center (Bloomington, IN, USA) ; UAS-EGFP 5a.2). The ImpL2 i (P{KK112218}VIE-260B) line was from Vienna Drosophila RNAi Center, EcR i #1 (UAS-EcR-RNAi) line was from NIG-Fly, ywhsFlp; pmCherry-Atg8a; Act > CD2 > GAL4, UAS-nlsGFP/TM6B from E. Baehrecke, hsFLP; Ubi-GFP FRT-40A, tkv 5 FRT-40A /CyO, and UAS-Dad from H. Richardson (La Trobe University, Vic., Australia), and tub-Gal80ts from G. Hime (Melbourne University, Vic., Australia. The control was w 1118 crossed to the driver line.…”

“…Cell size was quantitated using ImageJ [58]. To generate mutant clones hsFlp; ubi-GFP FRT-40A was crossed to Mad FRT-40A/CyO actGFP and tkv 5 FRT-40A/CyO actGFP mutant allele lines on the same chromosome as the FRT. The cross was allowed to lay for 8 h then embryos were heat shock at 37°C for 60 min.…”

“…Although caspasedependent apoptosis is the primary mode of developmental PCD, context specific modes of cell death that are dependent on autophagy, the catabolic process of cellular self-digestion through the action of lysosomal enzymes, also play a critical role [2][3][4][5]. Steroid hormones are important regulators of physiology and developmental transitions such as puberty in mammals and metamorphosis in insects [6].…”

Cucurbitacin I induces cancer cell death through the endoplasmic reticulum stress pathway

“…Cell death includes apoptosis‐dependent and ‐independent cell death . Nonapoptotic forms of cell death include necroptosis, autophagic cell death, pyroptosis, and caspase‐independent cell death .…”