Limits...
Neuroprotection by selective neuronal deletion of Atg7 in neonatal brain injury.

Xie C, Ginet V, Sun Y, Koike M, Zhou K, Li T, Li H, Li Q, Wang X, Uchiyama Y, Truttmann AC, Kroemer G, Puyal J, Blomgren K, Zhu C - Autophagy (2016)

Bottom Line: There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI).Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death.Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells.

View Article: PubMed Central - PubMed

Affiliation: a Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg , Gothenburg , Sweden.

ABSTRACT
Perinatal asphyxia induces neuronal cell death and brain injury, and is often associated with irreversible neurological deficits in children. There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI). We here investigated the selective neuronal deletion of the Atg7 (autophagy related 7) gene on neuronal cell death and brain injury in a mouse model of severe neonatal hypoxia-ischemia. Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death. Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells. These findings reveal that selective neuronal deletion of Atg7 is strongly protective against neuronal death and overall brain injury occurring after HI and suggest that inhibition of HI-enhanced autophagy should be considered as a potential therapeutic target for the treatment of human newborns developing severe hypoxic-ischemic encephalopathy.

No MeSH data available.


Related in: MedlinePlus

Neuronal Atg7 deficiency reduced hypoxia-ischemia-induced neuronal autophagy and brain injury. (A) Representative immunoblots of LC3BB from non-HI control (Cont) and HI ipsilateral (IL) hemispheres of Ctrl and atg7 KO mice 24 h after HI and the corresponding quantification of LC3BB-II showed that Atg7 deletion completely prevented HI-induced LC3BB-II increase, (*P < 0.05, n = 6/group). (B) Representative MAP2 staining in the ipsilateral hemisphere of the hippocampus (left) and striatum (right) level with the indication of MAP2 negative areas. (C) Representative MAP2 staining of coronal brain sections 8 d after HI at the levels of the dorsal hippocampus (left panels) and striatum (right panels) from Ctrl and atg7 KO mice and (D) measure of total tissue loss volume demonstrated a strong reduction of the lesion in the atg7 KO mice (Ctrl: n = 38, atg7 KO: n = 28), (**, P < 0.01). (E) Pathological scores performed in the cortex (Cx), hippocampus (Hip), striatum (Str), and thalamus (Tha) confirmed the greater resistance of atg7 KO mice compared to Ctrl mice, **, P < 0.01. (F) There was no difference in the neuroprotection provided by Atg7 deletion between males (Ctrl: n = 22, atg7 KO: n = 16) and females (Ctrl: n = 16, atg7 KO: n = 12) (*, P < 0.05). (G) The neuronal cell architecture in the Ctrl and atg7 KO mice in non-HI control and 24 h after HI indicated that dying neurons with condensed chromatin were more frequent in Ctrl than in atg7 KO. Squared areas are enlarged in the right panels. Moreover, the neuronal architecture was relatively well preserved in the atg7 KO mouse compared to that of the Ctrl mice. KO: atg7 KO (Atg7flox/flox; Nes-Cre) and Ctrl: Atg7flox/+; Nes-Cre.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4835980&req=5

f0003: Neuronal Atg7 deficiency reduced hypoxia-ischemia-induced neuronal autophagy and brain injury. (A) Representative immunoblots of LC3BB from non-HI control (Cont) and HI ipsilateral (IL) hemispheres of Ctrl and atg7 KO mice 24 h after HI and the corresponding quantification of LC3BB-II showed that Atg7 deletion completely prevented HI-induced LC3BB-II increase, (*P < 0.05, n = 6/group). (B) Representative MAP2 staining in the ipsilateral hemisphere of the hippocampus (left) and striatum (right) level with the indication of MAP2 negative areas. (C) Representative MAP2 staining of coronal brain sections 8 d after HI at the levels of the dorsal hippocampus (left panels) and striatum (right panels) from Ctrl and atg7 KO mice and (D) measure of total tissue loss volume demonstrated a strong reduction of the lesion in the atg7 KO mice (Ctrl: n = 38, atg7 KO: n = 28), (**, P < 0.01). (E) Pathological scores performed in the cortex (Cx), hippocampus (Hip), striatum (Str), and thalamus (Tha) confirmed the greater resistance of atg7 KO mice compared to Ctrl mice, **, P < 0.01. (F) There was no difference in the neuroprotection provided by Atg7 deletion between males (Ctrl: n = 22, atg7 KO: n = 16) and females (Ctrl: n = 16, atg7 KO: n = 12) (*, P < 0.05). (G) The neuronal cell architecture in the Ctrl and atg7 KO mice in non-HI control and 24 h after HI indicated that dying neurons with condensed chromatin were more frequent in Ctrl than in atg7 KO. Squared areas are enlarged in the right panels. Moreover, the neuronal architecture was relatively well preserved in the atg7 KO mouse compared to that of the Ctrl mice. KO: atg7 KO (Atg7flox/flox; Nes-Cre) and Ctrl: Atg7flox/+; Nes-Cre.

Mentions: The effects of neuronal Atg7 deficiency on HI-induced autophagy and brain injury were evaluated. In atg7 KO mice, the LC3B-II HI-dependent increase was completely prevented (Fig. 3A). Furthermore, at the ultrastructural level, no autophagosomes were observed in atg7 KO mice (data not shown) confirming that ATG7 deficiency efficiently prevented HI-induced neuronal autophagy.Figure 3.


Neuroprotection by selective neuronal deletion of Atg7 in neonatal brain injury.

Xie C, Ginet V, Sun Y, Koike M, Zhou K, Li T, Li H, Li Q, Wang X, Uchiyama Y, Truttmann AC, Kroemer G, Puyal J, Blomgren K, Zhu C - Autophagy (2016)

Neuronal Atg7 deficiency reduced hypoxia-ischemia-induced neuronal autophagy and brain injury. (A) Representative immunoblots of LC3BB from non-HI control (Cont) and HI ipsilateral (IL) hemispheres of Ctrl and atg7 KO mice 24 h after HI and the corresponding quantification of LC3BB-II showed that Atg7 deletion completely prevented HI-induced LC3BB-II increase, (*P < 0.05, n = 6/group). (B) Representative MAP2 staining in the ipsilateral hemisphere of the hippocampus (left) and striatum (right) level with the indication of MAP2 negative areas. (C) Representative MAP2 staining of coronal brain sections 8 d after HI at the levels of the dorsal hippocampus (left panels) and striatum (right panels) from Ctrl and atg7 KO mice and (D) measure of total tissue loss volume demonstrated a strong reduction of the lesion in the atg7 KO mice (Ctrl: n = 38, atg7 KO: n = 28), (**, P < 0.01). (E) Pathological scores performed in the cortex (Cx), hippocampus (Hip), striatum (Str), and thalamus (Tha) confirmed the greater resistance of atg7 KO mice compared to Ctrl mice, **, P < 0.01. (F) There was no difference in the neuroprotection provided by Atg7 deletion between males (Ctrl: n = 22, atg7 KO: n = 16) and females (Ctrl: n = 16, atg7 KO: n = 12) (*, P < 0.05). (G) The neuronal cell architecture in the Ctrl and atg7 KO mice in non-HI control and 24 h after HI indicated that dying neurons with condensed chromatin were more frequent in Ctrl than in atg7 KO. Squared areas are enlarged in the right panels. Moreover, the neuronal architecture was relatively well preserved in the atg7 KO mouse compared to that of the Ctrl mice. KO: atg7 KO (Atg7flox/flox; Nes-Cre) and Ctrl: Atg7flox/+; Nes-Cre.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835980&req=5

f0003: Neuronal Atg7 deficiency reduced hypoxia-ischemia-induced neuronal autophagy and brain injury. (A) Representative immunoblots of LC3BB from non-HI control (Cont) and HI ipsilateral (IL) hemispheres of Ctrl and atg7 KO mice 24 h after HI and the corresponding quantification of LC3BB-II showed that Atg7 deletion completely prevented HI-induced LC3BB-II increase, (*P < 0.05, n = 6/group). (B) Representative MAP2 staining in the ipsilateral hemisphere of the hippocampus (left) and striatum (right) level with the indication of MAP2 negative areas. (C) Representative MAP2 staining of coronal brain sections 8 d after HI at the levels of the dorsal hippocampus (left panels) and striatum (right panels) from Ctrl and atg7 KO mice and (D) measure of total tissue loss volume demonstrated a strong reduction of the lesion in the atg7 KO mice (Ctrl: n = 38, atg7 KO: n = 28), (**, P < 0.01). (E) Pathological scores performed in the cortex (Cx), hippocampus (Hip), striatum (Str), and thalamus (Tha) confirmed the greater resistance of atg7 KO mice compared to Ctrl mice, **, P < 0.01. (F) There was no difference in the neuroprotection provided by Atg7 deletion between males (Ctrl: n = 22, atg7 KO: n = 16) and females (Ctrl: n = 16, atg7 KO: n = 12) (*, P < 0.05). (G) The neuronal cell architecture in the Ctrl and atg7 KO mice in non-HI control and 24 h after HI indicated that dying neurons with condensed chromatin were more frequent in Ctrl than in atg7 KO. Squared areas are enlarged in the right panels. Moreover, the neuronal architecture was relatively well preserved in the atg7 KO mouse compared to that of the Ctrl mice. KO: atg7 KO (Atg7flox/flox; Nes-Cre) and Ctrl: Atg7flox/+; Nes-Cre.
Mentions: The effects of neuronal Atg7 deficiency on HI-induced autophagy and brain injury were evaluated. In atg7 KO mice, the LC3B-II HI-dependent increase was completely prevented (Fig. 3A). Furthermore, at the ultrastructural level, no autophagosomes were observed in atg7 KO mice (data not shown) confirming that ATG7 deficiency efficiently prevented HI-induced neuronal autophagy.Figure 3.

Bottom Line: There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI).Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death.Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells.

View Article: PubMed Central - PubMed

Affiliation: a Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg , Gothenburg , Sweden.

ABSTRACT
Perinatal asphyxia induces neuronal cell death and brain injury, and is often associated with irreversible neurological deficits in children. There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI). We here investigated the selective neuronal deletion of the Atg7 (autophagy related 7) gene on neuronal cell death and brain injury in a mouse model of severe neonatal hypoxia-ischemia. Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death. Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells. These findings reveal that selective neuronal deletion of Atg7 is strongly protective against neuronal death and overall brain injury occurring after HI and suggest that inhibition of HI-enhanced autophagy should be considered as a potential therapeutic target for the treatment of human newborns developing severe hypoxic-ischemic encephalopathy.

No MeSH data available.


Related in: MedlinePlus