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Atp8a1 deficiency is associated with phosphatidylserine externalization in hippocampus and delayed hippocampus‐dependent learning
Author(s) -
Levano Kelly,
Punia Vineet,
Raghunath Michael,
Debata Priya Ranjan,
Curcio Gina Marie,
Mogha Amit,
Purkayastha Sudarshana,
McCloskey Dan,
Fata Jimmie,
Banerjee Probal
Publication year - 2012
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2011.07543.x
Subject(s) - phosphatidylserine , biology , dentate gyrus , microbiology and biotechnology , hippocampal formation , population , apoptosis , hippocampus , medicine , endocrinology , biochemistry , phospholipid , membrane , environmental health
J. Neurochem. (2012) 120 , 302–313. Abstract The molecule responsible for the enzyme activity plasma membrane (PM) aminophospholipid translocase (APLT), which catalyzes phosphatidylserine (PS) translocation from the outer to the inner leaflet of the plasma membrane, is unknown in mammals. A Caenorhabditis elegans study has shown that ablation of transbilayer amphipath transporter‐1 (TAT‐1), which is an ortholog of a mammalian P‐type ATPase, Atp8a1, causes PS externalization in the germ cells. We demonstrate here that the hippocampal cells of the dentate gyrus, and Cornu Ammonis (CA1, CA3) in mice lacking Atp8a1 exhibit a dramatic increase in PS externalization. Although their hippocampi showed no abnormal morphology or heightened apoptosis, these mice displayed increased activity and a marked deficiency in hippocampus‐dependent learning, but no hyper‐anxiety. Such observations indicate that Atp8a1 plays a crucial role in PM‐APLT activity in the neuronal cells. In corroboration, ectopic expression of Atp8a1 but not its close homolog, Atp8a2, caused an increase in the population ( V max ) of PM‐APLT without any change in its signature parameter K m in the neuronal N18 cells. Conversely, expression of a P‐type phosphorylation‐site mutant of Atp8a1 (Atp8a1*) caused a decrease in V max of PM‐APLT without significantly altering its K m . The Atp8a1*‐expressing N18 cells also exhibited PS externalization without apoptosis. Together, our data strongly indicate that Atp8a1 plays a central role in the PM‐APLT activity of some mammalian cells, such as the neuronal N18 and hippocampal cells.