| First Author | Turati J | Year | 2022 |
| Journal | J Neurochem | Volume | 161 |
| Issue | 4 | Pages | 366-382 |
| PubMed ID | 35411603 | Mgi Jnum | J:354102 |
| Mgi Id | MGI:7330291 | Doi | 10.1111/jnc.15610 |
| Citation | Turati J, et al. (2022) A metabotropic glutamate receptor 3 (mGlu3R) isoform playing neurodegenerative roles in astrocytes is prematurely up-regulated in an Alzheimer's model. J Neurochem 161(4):366-382 |
| abstractText | Subtype 3 metabotropic glutamate receptor (mGlu3R) displays a broad range of neuroprotective effects. We previously demonstrated that mGlu3R activation in astrocytes protects hippocampal neurons from Abeta neurotoxicity through stimulation of both neurotrophin release and Abeta uptake. Alternative-spliced variants of mGlu3R were found in human brains. The most prevalent variant, mGlu3Delta4, lacks exon 4 encoding the transmembrane domain and can inhibit ligand binding to mGlu3R. To date, neither its role in neurodegenerative disorders nor its endogenous expression in CNS cells has been addressed. The present paper describes for the first time an association between altered hippocampal expression of mGlu3Delta4 and Alzheimer's disease (AD) in the preclinical murine model PDAPP-J20, as well as a deleterious effect of mGlu3Delta4 in astrocytes. As assessed by western blot, hippocampal mGlu3R levels progressively decreased with age in PDAPP-J20 mice. On the contrary, mGlu3Delta4 levels were drastically increased with aging in nontransgenic mice, but prematurely over-expressed in 5-month-old PDAPP-J20-derived hippocampi, prior to massive senile plaque deposition. Also, we found that mGlu3Delta4 co-precipitated with mGlu3R mainly in 5-month-old PDAPP-J20 mice. We further showed by western blot that primary cultured astrocytes and neurons expressed mGlu3Delta4, whose levels were reduced by Abeta, thereby discouraging a causal effect of Abeta on mGlu3Delta4 induction. However, heterologous expression of mGlu3Delta4 in astrocytes induced cell death, inhibited mGlu3R expression, and prevented mGlu3R-dependent Abeta glial uptake. Indeed, mGlu3Delta4 promoted neurodegeneration in neuron-glia co-cultures. These results provide evidence of an inhibitory role of mGlu3Delta4 in mGlu3R-mediated glial neuroprotective pathways, which may lie behind AD onset. |
