Calcineurin is involved in the early activation of NMDA‐mediated cell death in mutant huntingtin knock‐in striatal cells

Abstract

Excitotoxicity has been proposed as one of the mechanisms involved in the specific loss of striatal neurons that occurs in Huntington’s disease. Here, we studied the role of calcineurin in the vulnerability of striatal neurons expressing mutant huntingtin to excitotoxicity. To this end, we induced excitotoxicity by adding NMDA to a striatal precursor cell line expressing full‐length wild‐type (STHdhQ7/Q7) or mutant (STHdhQ111/Q111) huntingtin. We observed that cell death appeared earlier in STHdhQ111/Q111 cells than in STHdhQ7/Q7 cells. Interestingly, these former cells expressed higher levels of calcineurin A that resulted in a greater increase of its activity after NMDA receptor stimulation. Moreover, transfection of full‐length mutant huntingtin in different striatal‐derived cells (STHdhQ7/Q7, M213 and primary cultures) increased calcineurin A protein levels. To determine whether high levels of calcineurin A might account for the earlier activation of cell death in mutant huntingtin knock‐in cells, wild‐type cells were transfected with calcineurin A. Calcineurin A‐transfected STHdhQ7/Q7 cells displayed a significant increase in cell death compared with that recorded in green fluorescent protein‐transfected cells after NMDA treatment. Notably, addition of the calcineurin inhibitor FK‐506 produced a more robust reduction in cell death in mutant huntingtin knock‐in cells than it did in wild‐type cells. These results suggest that high levels of calcineurin A could account for the increased vulnerability of striatal cells expressing mutant huntingtin to excitotoxicity.

Dopaminergic and Glutamatergic Signaling Crosstalk in Huntington's Disease Neurodegeneration: The Role of p25/Cyclin-Dependent Kinase 5

“…which, per se, are not toxic (Xifró et al, 2008). Notably, either toxic or subtoxic NMDA concentrations enhanced the effect in cell death mediated by SKF38393 only in mutant STHdh Q111 cells.…”

“…Thus, our results imply that D 1 receptor activation mediates the dopaminergic toxic effect observed in wild-type and mutant knock-in striatal cells and that full-length mutant huntingtin expression potentiates dopamine-cell death through D 1 but not D 2 receptors. NMDA enhances dopamine D 1 receptor-mediated cell death selectively in STHdh Q111 cells Previous results from our laboratory have demonstrated that mutant STHdh Q111 striatal cells display enhanced sensitivity to NMDA receptor activation (Xifró et al, 2008). Therefore, we next analyzed whether NMDA treatment potentiates the neurotoxic effect of dopamine.…”

Interaction of Postsynaptic Density Protein-95 with NMDA Receptors Influences Excitotoxicity in the Yeast Artificial Chromosome Mouse Model of Huntington's Disease

“…Calcineurin and PSD-95 are linked through binding with A-kinase anchoring protein (AKAP79/150) (Colledge et al, 2000;Bhattacharyya et al, 2009). Moreover, NMDAR-induced calcineurin activity is enhanced in mutant htt-expressing striatal cells, and inhibition of calcineurin protects against excitotoxicity better in mutant htt-expressing than WT cells (Xifró et al, 2008). Another apoptotic pathway downstream of PSD-95 is through binding to synaptic Ras-GTPase activating protein, known to regulate synaptic plasticity and neuronal apoptosis through p38 -MAPK signaling (Kim et al, 1998;Rumbaugh et al, 2006).…”

Micro RNA -214,-150,-146a and-125b targetHuntingtingene

“…20 This cell model of HD has been extensively used for identifying molecular alterations in HD. [41][42][43][44][45][46][47][48] Cell culture and transfection. (Cat No.…”