ABSTRACT
Neuropsychiatric disorders are the leading cause of mental and intellectual disabilities worldwide. Current therapies against neuropsychiatric disorders are very limited, and very little is known about the onset and development of these diseases, and their most effective treatments. MIR137 has been previously identified as a risk gene for the etiology of schizophrenia, bipolar disorder, and autism spectrum disorder. Here we generated a forebrain-specific MIR137 knockout mouse model, and provided evidence that loss of miR-137 resulted in impaired homeostasis of potassium in mouse hippocampal neurons. KCC2, a potassium-chloride co-transporter, was a direct downstream target of miR-137. The KCC2 specific antagonist VU0240551 could balance the current of potassium in miR-137 knockout neurons, and knockdown of KCC2 could ameliorate anxiety-like behavior in MIR137 cKO mice. These data suggest that KCC2 antagonists or knockdown might be beneficial to neuropsychiatric disorders due to the deficiency of miR-137.
ABSTRACT
<p><b>OBJECTIVE</b>To study the role of presenilin1 (PS1) in the processing of beta-amyloid precursor protein (APP) to amyloid beta-peptide (Abeta) and its relation to gamma-secretase in the pathogenesis of Alzheimer's disease (AD).</p><p><b>METHODS</b>Several CHO cell lines stably transfected with either wide-type or mutant PS1 (M(146)L) along with APP(751) genes were established. The expression of PS1 and its half-life were determined by immunoprecipitation, Western blotting and pulse-chase experiment. Abeta released into the conditional media was quantitated by ELISA.</p><p><b>RESULTS</b>PS1 transfected CHO cells expressed an expected 45,000 full length protein. This over-expressed full length PS1 was subject to fast degradation with a half-life of less than 1 hour. In contrast to full length PS1, the truncated N-terminal and C-terminal proteins of PS1 were significantly more stable with a longer half-life of nearly 16 hours. Although the total amount of Abeta released into the conditional media did not show a significant difference between wild-type and mutant PS1 (M(146)L) transfected APP cells, mutant PS1 (M(146)L) transfected APP cells increase Abeta(1 - 42) (a subspecies of total Abeta) production with nearly a 2 fold increase, comparing to untransfected or wild-type PS1 transfected APP cells.</p><p><b>CONCLUSION</b>PS1 is involved in the processing of APP to Abeta, a nearly 2 fold increase of Abeta production in mutant PS1 (M(146)L) transfected APP cells indicates that PS1 may be the expected gamma-secretase itself.</p>
Subject(s)
Animals , Cricetinae , Alzheimer Disease , Metabolism , Amyloid Precursor Protein Secretases , Genetics , Metabolism , Amyloid beta-Peptides , Metabolism , Amyloid beta-Protein Precursor , Genetics , CHO Cells , Cricetulus , Mutation , Peptide Fragments , Metabolism , Presenilin-1 , Genetics , Metabolism , TransfectionABSTRACT
<p><b>OBJECTIVE</b>To study the effects and mechanism of hydrogen peroxide (H2O2) of low concentration on dynamic changes of intracellular free calcium contents ([Ca2+]i) in cultural rat liver oval cells (WB-F344 cells).</p><p><b>METHODS</b>Using Fluo-3/Am as fluorescent indicator of [Ca2+]i and it was measured by laser scanning confocal microscope system.</p><p><b>RESULTS</b>The results showed that: (1) A rapid transient spiking of [Ca2+]i occurred after the stimulation of H2O2 of low concentration (800 nmol/L). (2) The [Ca2+]i increase was abolished by pretreated with catalase (CAT) or by incubated in D-Hank's solution containing EGTA, the chelate of extracellular Ca2+. (3) The [Ca2+]i increase was not inhibited by pretreated nifedipine, Ca2+ channel blocker, but was abolished by pretreated with anthracere-9-cardoxylic acid (A9C), the Cl-channel blocker and which also blocked calcium activated non-selective cation channel (CAN).</p><p><b>CONCLUSIONS</b>These results suggest that the increase of [Ca2+]i induced by H2O2 of low concentration may be due to the influx of extracellular Ca2+ through CAN.</p>