C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent Manner
Dysfunctional autophagy or ubiquitin-proteasome system (UPS) are suggested to underlie abnormal protein aggregation in neurodegenerative diseases. Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS)-associated <i>C9orf72</i> is implicated in autophagy, but whether it ac...
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MDPI AG
2019-10-01
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| Online Access: | https://www.mdpi.com/2073-4409/8/10/1233 |
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| author | Stina Leskelä Nadine Huber Hannah Rostalski Teemu Natunen Anne M. Remes Mari Takalo Mikko Hiltunen Annakaisa Haapasalo |
| author_facet | Stina Leskelä Nadine Huber Hannah Rostalski Teemu Natunen Anne M. Remes Mari Takalo Mikko Hiltunen Annakaisa Haapasalo |
| author_sort | Stina Leskelä |
| collection | DOAJ |
| description | Dysfunctional autophagy or ubiquitin-proteasome system (UPS) are suggested to underlie abnormal protein aggregation in neurodegenerative diseases. Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS)-associated <i>C9orf72</i> is implicated in autophagy, but whether it activates or inhibits autophagy is partially controversial. Here, we utilized knockdown or overexpression of <i>C9orf72</i> in mouse N2a neuroblastoma cells or cultured neurons to elucidate the potential role of C9orf72 proteins in autophagy and UPS. Induction of autophagy in <i>C9orf72</i> knockdown N2a cells led to decreased LC3BI to LC3BII conversion, p62 degradation, and formation of LC3-containing autophagosomes, suggesting compromised autophagy. Proteasomal activity was slightly decreased. No changes in autophagy nor proteasomal activity in C9orf72-overexpressing N2a cells were observed. However, in these cells, autophagy induction by serum starvation or rapamycin led to significantly decreased C9orf72 levels. The decreased levels of C9orf72 in serum-starved N2a cells were restored by the proteasomal inhibitor lactacystin, but not by the autophagy inhibitor bafilomycin A1 (BafA1) treatment. These data suggest that C9orf72 undergoes proteasomal degradation in N2a cells during autophagy. Lactacystin significantly elevated C9orf72 levels in N2a cells and neurons, further suggesting UPS-mediated regulation. In rapamycin and BafA1-treated neurons, C9orf72 levels were significantly increased. Altogether, these findings corroborate the previously suggested regulatory role for C9orf72 in autophagy and suggest cell type-dependent regulation of C9orf72 levels via UPS and/or autophagy. |
| first_indexed | 2024-03-12T06:04:08Z |
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| language | English |
| last_indexed | 2024-03-12T06:04:08Z |
| publishDate | 2019-10-01 |
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| series | Cells |
| spelling | doaj.art-c9b4569e0b284adbac56383fede625f72023-09-03T03:53:26ZengMDPI AGCells2073-44092019-10-01810123310.3390/cells8101233cells8101233C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent MannerStina Leskelä0Nadine Huber1Hannah Rostalski2Teemu Natunen3Anne M. Remes4Mari Takalo5Mikko Hiltunen6Annakaisa Haapasalo7A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Neulaniementie 2, 70211 Kuopio, FinlandA. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Neulaniementie 2, 70211 Kuopio, FinlandA. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Neulaniementie 2, 70211 Kuopio, FinlandInstitute of Biomedicine, Yliopistonranta 1E, University of Eastern Finland, 70211 Kuopio, FinlandUnit of Clinical Neuroscience, Neurology, University of Oulu, P.O. Box 8000, University of Oulu, 90014 Oulu, FinlandInstitute of Biomedicine, Yliopistonranta 1E, University of Eastern Finland, 70211 Kuopio, FinlandInstitute of Biomedicine, Yliopistonranta 1E, University of Eastern Finland, 70211 Kuopio, FinlandA. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Neulaniementie 2, 70211 Kuopio, FinlandDysfunctional autophagy or ubiquitin-proteasome system (UPS) are suggested to underlie abnormal protein aggregation in neurodegenerative diseases. Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS)-associated <i>C9orf72</i> is implicated in autophagy, but whether it activates or inhibits autophagy is partially controversial. Here, we utilized knockdown or overexpression of <i>C9orf72</i> in mouse N2a neuroblastoma cells or cultured neurons to elucidate the potential role of C9orf72 proteins in autophagy and UPS. Induction of autophagy in <i>C9orf72</i> knockdown N2a cells led to decreased LC3BI to LC3BII conversion, p62 degradation, and formation of LC3-containing autophagosomes, suggesting compromised autophagy. Proteasomal activity was slightly decreased. No changes in autophagy nor proteasomal activity in C9orf72-overexpressing N2a cells were observed. However, in these cells, autophagy induction by serum starvation or rapamycin led to significantly decreased C9orf72 levels. The decreased levels of C9orf72 in serum-starved N2a cells were restored by the proteasomal inhibitor lactacystin, but not by the autophagy inhibitor bafilomycin A1 (BafA1) treatment. These data suggest that C9orf72 undergoes proteasomal degradation in N2a cells during autophagy. Lactacystin significantly elevated C9orf72 levels in N2a cells and neurons, further suggesting UPS-mediated regulation. In rapamycin and BafA1-treated neurons, C9orf72 levels were significantly increased. Altogether, these findings corroborate the previously suggested regulatory role for C9orf72 in autophagy and suggest cell type-dependent regulation of C9orf72 levels via UPS and/or autophagy.https://www.mdpi.com/2073-4409/8/10/1233amyotrophic lateral sclerosisautophagy<i>c9orf72</i>frontotemporal dementiaproteasomal degradationubiquitin-proteasome system |
| spellingShingle | Stina Leskelä Nadine Huber Hannah Rostalski Teemu Natunen Anne M. Remes Mari Takalo Mikko Hiltunen Annakaisa Haapasalo C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent Manner Cells amyotrophic lateral sclerosis autophagy <i>c9orf72</i> frontotemporal dementia proteasomal degradation ubiquitin-proteasome system |
| title | C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent Manner |
| title_full | C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent Manner |
| title_fullStr | C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent Manner |
| title_full_unstemmed | C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent Manner |
| title_short | C9orf72 Proteins Regulate Autophagy and Undergo Autophagosomal or Proteasomal Degradation in a Cell Type-Dependent Manner |
| title_sort | c9orf72 proteins regulate autophagy and undergo autophagosomal or proteasomal degradation in a cell type dependent manner |
| topic | amyotrophic lateral sclerosis autophagy <i>c9orf72</i> frontotemporal dementia proteasomal degradation ubiquitin-proteasome system |
| url | https://www.mdpi.com/2073-4409/8/10/1233 |
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