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HERC 1 Ubiquitin Ligase Mutation Affects Neocortical, CA3 Hippocampal and Spinal Cord Projection Neurons: An Ultrastructural Study.

Ruiz R, Pérez-Villegas EM, Bachiller S, Rosa JL, Armengol JA - Front Neuroanat (2016)

Bottom Line: The main difference is that the reduction in the number of neurons affected in the tambaleante mutation in the neocortex, the hippocampus, and the spinal cord is not so evident as the dramatic loss of cerebellar Purkinje cells.Affected neurons have in common that they are projection neurons which receive strong and varied synaptic inputs, and possess the highest degree of neuronal activity.Therefore, because the integrity of the ubiquitin-proteasome system is essential for protein degradation and hence, for normal protein turnover, it could be hypothesized that the deleterious effects of the misrouting of these pathways would depend directly on the neuronal activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of SevilleSeville, Spain; Department of Physiology, Anatomy and Cell Biology, University Pablo de OlavideSeville, Spain.

ABSTRACT
The spontaneous mutation tambaleante is caused by the Gly483Glu substitution in the highly conserved N terminal RCC1-like domain of the HERC1 protein, which leads to the increase of mutated protein levels responsible for cerebellar Purkinje cell death by autophagy. Until now, Purkinje cells have been the only central nervous neurons reported as being targeted by the mutation, and their degeneration elicits an ataxic syndrome in adult mutant mice. However, the ultrastructural analysis performed here demonstrates that signs of autophagy, such as autophagosomes, lysosomes, and altered mitochondria, are present in neocortical pyramidal, CA3 hippocampal pyramidal, and spinal cord motor neurons. The main difference is that the reduction in the number of neurons affected in the tambaleante mutation in the neocortex, the hippocampus, and the spinal cord is not so evident as the dramatic loss of cerebellar Purkinje cells. Interestingly, signs of autophagy are absent in both interneurons and neuroglia cells. Affected neurons have in common that they are projection neurons which receive strong and varied synaptic inputs, and possess the highest degree of neuronal activity. Therefore, because the integrity of the ubiquitin-proteasome system is essential for protein degradation and hence, for normal protein turnover, it could be hypothesized that the deleterious effects of the misrouting of these pathways would depend directly on the neuronal activity.

No MeSH data available.


Related in: MedlinePlus

Confocal images of coronal sections through the frontal cortex layers II-III (A–C) of 4-month-old wt mice, and the frontal cortex (D–F) of 4-month-old tbl/tbl mice. p62 immunoreactive is stronger in tbl/tbl cortex (E) than in wt cortex (B); and in both wt(C) and tbl/tbl(F) co-express in calbindin (CaBP) immunoreactive neuronal cell bodies. I, layer I. Bars = 50 μm.
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Figure 9: Confocal images of coronal sections through the frontal cortex layers II-III (A–C) of 4-month-old wt mice, and the frontal cortex (D–F) of 4-month-old tbl/tbl mice. p62 immunoreactive is stronger in tbl/tbl cortex (E) than in wt cortex (B); and in both wt(C) and tbl/tbl(F) co-express in calbindin (CaBP) immunoreactive neuronal cell bodies. I, layer I. Bars = 50 μm.

Mentions: The immunohistochemical study showed a prevalence of autophagy markers immunostaining in areas occupied by pyramidal cells as the pyramidal layer of the CA3 of the hippocampus and the layers II-III and V of the frontal neocortex (Figures 7, 8, 9), while layers I, IV and VI possessed a weak or occasionally inexistent labeling. The marker of the early stage of vesicle nucleation leading to the formation of autophagosomes beclin-1 (Kihara et al., 2001) was expressed in calbindin immunoreactive and calbindin non immunoreactive cell somata, and in all cases was more abundant in the cerebral cortex (Figures 7D–F) and the hippocampal CA3 region of tbl/tbl mice (Figures 7J–L) than in the same brain areas of wt mice (Figures 7A–C,G–I). The same immunohistochemical results were obtained by detecting the expression of the microtubule-associated protein—LC3, in which LC3 co-expressed with NeuN labeled somata more strongly in the cerebral cortex (Figures 8D–F) and hippocampal CA3 area (Figures 8J–L) of tbl/tbl mice than of wt mice (Figures 8A–C,G–I, respectively). Qualitatively, the most evident difference of the presence of autophagic vacuoles between tbl/tbl (Figures 9D–F) and wt (Figures 9A–C) mice was found in the detection of the expression of the LC3-phospatidylethanolamine complex binder p62 (Franchi et al., 2012), which is co-expressed in calbindin immunoreactive neuronal cell bodies and dendrites. Therefore, present immunohistochemical analyses of the autophagic vacuole formation cycle demonstrated the presence of a fine grained labeling within the neuronal cytoplasms (Figures 7, 8, 9) congruent with electron microscopy findings, which in all cases was more evident in the tbl/tbl than in wt brains.


HERC 1 Ubiquitin Ligase Mutation Affects Neocortical, CA3 Hippocampal and Spinal Cord Projection Neurons: An Ultrastructural Study.

Ruiz R, Pérez-Villegas EM, Bachiller S, Rosa JL, Armengol JA - Front Neuroanat (2016)

Confocal images of coronal sections through the frontal cortex layers II-III (A–C) of 4-month-old wt mice, and the frontal cortex (D–F) of 4-month-old tbl/tbl mice. p62 immunoreactive is stronger in tbl/tbl cortex (E) than in wt cortex (B); and in both wt(C) and tbl/tbl(F) co-express in calbindin (CaBP) immunoreactive neuronal cell bodies. I, layer I. Bars = 50 μm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4834294&req=5

Figure 9: Confocal images of coronal sections through the frontal cortex layers II-III (A–C) of 4-month-old wt mice, and the frontal cortex (D–F) of 4-month-old tbl/tbl mice. p62 immunoreactive is stronger in tbl/tbl cortex (E) than in wt cortex (B); and in both wt(C) and tbl/tbl(F) co-express in calbindin (CaBP) immunoreactive neuronal cell bodies. I, layer I. Bars = 50 μm.
Mentions: The immunohistochemical study showed a prevalence of autophagy markers immunostaining in areas occupied by pyramidal cells as the pyramidal layer of the CA3 of the hippocampus and the layers II-III and V of the frontal neocortex (Figures 7, 8, 9), while layers I, IV and VI possessed a weak or occasionally inexistent labeling. The marker of the early stage of vesicle nucleation leading to the formation of autophagosomes beclin-1 (Kihara et al., 2001) was expressed in calbindin immunoreactive and calbindin non immunoreactive cell somata, and in all cases was more abundant in the cerebral cortex (Figures 7D–F) and the hippocampal CA3 region of tbl/tbl mice (Figures 7J–L) than in the same brain areas of wt mice (Figures 7A–C,G–I). The same immunohistochemical results were obtained by detecting the expression of the microtubule-associated protein—LC3, in which LC3 co-expressed with NeuN labeled somata more strongly in the cerebral cortex (Figures 8D–F) and hippocampal CA3 area (Figures 8J–L) of tbl/tbl mice than of wt mice (Figures 8A–C,G–I, respectively). Qualitatively, the most evident difference of the presence of autophagic vacuoles between tbl/tbl (Figures 9D–F) and wt (Figures 9A–C) mice was found in the detection of the expression of the LC3-phospatidylethanolamine complex binder p62 (Franchi et al., 2012), which is co-expressed in calbindin immunoreactive neuronal cell bodies and dendrites. Therefore, present immunohistochemical analyses of the autophagic vacuole formation cycle demonstrated the presence of a fine grained labeling within the neuronal cytoplasms (Figures 7, 8, 9) congruent with electron microscopy findings, which in all cases was more evident in the tbl/tbl than in wt brains.

Bottom Line: The main difference is that the reduction in the number of neurons affected in the tambaleante mutation in the neocortex, the hippocampus, and the spinal cord is not so evident as the dramatic loss of cerebellar Purkinje cells.Affected neurons have in common that they are projection neurons which receive strong and varied synaptic inputs, and possess the highest degree of neuronal activity.Therefore, because the integrity of the ubiquitin-proteasome system is essential for protein degradation and hence, for normal protein turnover, it could be hypothesized that the deleterious effects of the misrouting of these pathways would depend directly on the neuronal activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of SevilleSeville, Spain; Department of Physiology, Anatomy and Cell Biology, University Pablo de OlavideSeville, Spain.

ABSTRACT
The spontaneous mutation tambaleante is caused by the Gly483Glu substitution in the highly conserved N terminal RCC1-like domain of the HERC1 protein, which leads to the increase of mutated protein levels responsible for cerebellar Purkinje cell death by autophagy. Until now, Purkinje cells have been the only central nervous neurons reported as being targeted by the mutation, and their degeneration elicits an ataxic syndrome in adult mutant mice. However, the ultrastructural analysis performed here demonstrates that signs of autophagy, such as autophagosomes, lysosomes, and altered mitochondria, are present in neocortical pyramidal, CA3 hippocampal pyramidal, and spinal cord motor neurons. The main difference is that the reduction in the number of neurons affected in the tambaleante mutation in the neocortex, the hippocampus, and the spinal cord is not so evident as the dramatic loss of cerebellar Purkinje cells. Interestingly, signs of autophagy are absent in both interneurons and neuroglia cells. Affected neurons have in common that they are projection neurons which receive strong and varied synaptic inputs, and possess the highest degree of neuronal activity. Therefore, because the integrity of the ubiquitin-proteasome system is essential for protein degradation and hence, for normal protein turnover, it could be hypothesized that the deleterious effects of the misrouting of these pathways would depend directly on the neuronal activity.

No MeSH data available.


Related in: MedlinePlus