Editing of AMPA and serotonin 2C receptors in individual central neurons, controlling wakefulness.
(1) Pre-mRNA editing of serotonin 2C (5-HT2c) and glutamate (Glu) receptors (R) influences higher brain functions and pathological states such as epilepsy, amyotrophic lateral sclerosis, and depression. Adenosine deaminases acting on RNA (ADAR1-3) convert adenosine to inosine on synthetic RNAs, analogous to 5-HT2cR and GluR. The order of editing as well as mechanisms controlling editing in native neurons is unknown. (2) With single-cell RT-PCR we investigated the co-expression of ADAR genes with GluR and 5-HT2cR and determined the editing status at known sites in the hypothalamic tuberomamillary nucleus, a major center for wakefulness and arousal. (3) The most frequently expressed enzymes were ADAR1, followed by ADAR2. The Q/R site of GluR2 was always fully edited. Editing at the R/G site in the GluR2 (but not GluR4) subunit was co-ordinated with ADAR expression: maximal editing was found in neurons expressing both ADAR2 splice variants of the deaminase domain and lacking ADAR3. (4) Editing of the 5-HT2cR did not correlate with ADAR expression. The 5-HT2cR mRNA was always edited at A, in the majority of cells at B sites and variably edited at E, C and D sites. A negative correlation was found between editing of C and D sites. The GluR4 R/G site editing was homogeneous within individuals: it was fully edited in all neurons obtained from 12 rats and under-edited in six neurons obtained from three rats. (5) We conclude that GluR2 R/G editing is controlled at the level of ADAR2 and therefore this enzyme may be a target for pharmacotherapy. On the other hand, further factors/enzymes besides ADAR must control or influence 5-HT2cR and GluR pre-mRNA editing in native neurons; our data indicate that these factors vary between individuals and could be predictors of psychiatric disease.
Sergeeva
Olga A
OA
Department of Neurophysiology, Heinrich-Heine-Universität, POB 101007, 40001 Dusseldorf, Germany. olga.sergeeva@uni-duesseldorf.de
Amberger
Bettina T
BT
Haas
Helmut L
HL
D000243:Adenosine Deaminase / Q000235:genetics; D000818:Animals; D007034:Hypothalamus, Posterior / Q000166:cytology / Q000502:physiology; D008297:Male; D009474:Neurons / Q000502:physiology*; D017393:RNA Editing / Q000502:physiology*; D012322:RNA Precursors / Q000378:metabolism; D012326:RNA Splicing / Q000502:physiology; D016601:RNA-Binding Proteins; D051381:Rats; D017208:Rats, Wistar; D044405:Receptor, Serotonin, 5-HT2C / Q000235:genetics*; D018091:Receptors, AMPA / Q000235:genetics*; D014851:Wakefulness / Q000502:physiology*
D000243:Adenosine Deaminase; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D044405:Receptor, Serotonin, 5-HT2C; D018091:Receptors, AMPA; C104723:glutamate receptor ionotropic, AMPA 3; C104724:glutamate receptor ionotropic, AMPA 4; C567955:ADARB1 protein, human; C104722:glutamate receptor ionotropic, AMPA 2