TY - JOUR

T1 - Targeted deletion of the aquaglyceroporin AQP9 is protective in a mouse model of Parkinson’s disease

AU - Stahl, Katja

AU - Rahmani, Soulmaz

AU - Prydz, Agnete

AU - Skauli, Nadia

AU - MacAulay, Nanna

AU - Mylonakou, Maria N.

AU - Torp, Reidun

AU - Skare, Øivind

AU - Berg, Torill

AU - Leergaard, Trygve B.

AU - Paulsen, Ragnhild E.

AU - Ottersen, Ole P.

AU - Amiry-Moghaddam, Mahmood

PY - 2018

Y1 - 2018

N2 - More than 90% of the cases of Parkinson’s disease have unknown etiology. Gradual loss of dopaminergic neurons of substantia nigra is the main cause of morbidity in this disease. External factors such as environmental toxins are believed to play a role in the cell loss, although the cause of the selective vulnerability of dopaminergic neurons remains unknown. We have previously shown that aquaglyceroporin AQP9 is expressed in dopaminergic neurons and astrocytes of rodent brain. AQP9 is permeable to a broad spectrum of substrates including purines, pyrimidines, and lactate, in addition to water and glycerol. Here we test our hypothesis that AQP9 serves as an influx route for exogenous toxins and, hence, may contribute to the selective vulnerability of nigral dopaminergic (tyrosine hydroxylase-positive) neurons. Using Xenopus oocytes injected with Aqp9 cRNA, we show that AQP9 is permeable to the parkinsonogenic toxin 1-methyl-4-phenylpyridinium (MPP+). Stable expression of AQP9 in HEK cells increases their vulnerability to MPP+ and to arsenite—another parkinsonogenic toxin. Conversely, targeted deletion of Aqp9 in mice protects nigral dopaminergic neurons against MPP+ toxicity. A protective effect of Aqp9 deletion was demonstrated in organotypic slice cultures of mouse midbrain exposed to MPP+ in vitro and in mice subjected to intrastriatal injections of MPP+ in vivo. Seven days after intrastriatal MPP+ injections, the population of tyrosine hydroxylase-positive cells in substantia nigra is reduced by 48% in Aqp9 knockout mice compared with 67% in WT littermates. Our results show that AQP9 –selectively expressed in catecholaminergic neurons—is permeable to MPP+ and suggest that this aquaglyceroporin contributes to the selective vulnerability of nigral dopaminergic neurons by providing an entry route for parkinsonogenic toxins. To our knowledge this is the first evidence implicating a toxin permeable membrane channel in the pathophysi-ology of Parkinson’s disease.

AB - More than 90% of the cases of Parkinson’s disease have unknown etiology. Gradual loss of dopaminergic neurons of substantia nigra is the main cause of morbidity in this disease. External factors such as environmental toxins are believed to play a role in the cell loss, although the cause of the selective vulnerability of dopaminergic neurons remains unknown. We have previously shown that aquaglyceroporin AQP9 is expressed in dopaminergic neurons and astrocytes of rodent brain. AQP9 is permeable to a broad spectrum of substrates including purines, pyrimidines, and lactate, in addition to water and glycerol. Here we test our hypothesis that AQP9 serves as an influx route for exogenous toxins and, hence, may contribute to the selective vulnerability of nigral dopaminergic (tyrosine hydroxylase-positive) neurons. Using Xenopus oocytes injected with Aqp9 cRNA, we show that AQP9 is permeable to the parkinsonogenic toxin 1-methyl-4-phenylpyridinium (MPP+). Stable expression of AQP9 in HEK cells increases their vulnerability to MPP+ and to arsenite—another parkinsonogenic toxin. Conversely, targeted deletion of Aqp9 in mice protects nigral dopaminergic neurons against MPP+ toxicity. A protective effect of Aqp9 deletion was demonstrated in organotypic slice cultures of mouse midbrain exposed to MPP+ in vitro and in mice subjected to intrastriatal injections of MPP+ in vivo. Seven days after intrastriatal MPP+ injections, the population of tyrosine hydroxylase-positive cells in substantia nigra is reduced by 48% in Aqp9 knockout mice compared with 67% in WT littermates. Our results show that AQP9 –selectively expressed in catecholaminergic neurons—is permeable to MPP+ and suggest that this aquaglyceroporin contributes to the selective vulnerability of nigral dopaminergic neurons by providing an entry route for parkinsonogenic toxins. To our knowledge this is the first evidence implicating a toxin permeable membrane channel in the pathophysi-ology of Parkinson’s disease.

U2 - 10.1371/journal.pone.0194896

DO - 10.1371/journal.pone.0194896

M3 - Journal article

C2 - 29566083

AN - SCOPUS:85044284875

VL - 13

JO - PLoS ONE

JF - PLoS ONE

SN - 1932-6203

IS - 3

M1 - e0194896

ER -