Methyl-CpG binding-protein 2 function in cholinergic neurons mediates cardiac arrhythmogenesis.
Sudden unexpected death occurs in one quarter of deaths in Rett Syndrome (RTT), a neurodevelopmental disorder caused by mutations in Methyl-CpG-binding protein 2 (MECP2). People with RTT show a variety of autonomic nervous system (ANS) abnormalities and mouse models show similar problems including QTc interval prolongation and hypothermia. To explore the role of cardiac problems in sudden death in RTT, we characterized cardiac rhythm in mice lacking Mecp2 function. Male and female mutant mice exhibited spontaneous cardiac rhythm abnormalities including bradycardic events, sinus pauses, atrioventricular block, premature ventricular contractions, non-sustained ventricular arrhythmias, and increased heart rate variability. Death was associated with spontaneous cardiac arrhythmias and complete conduction block. Atropine treatment reduced cardiac arrhythmias in mutant mice, implicating overactive parasympathetic tone. To explore the role of MeCP2 within the parasympathetic neurons, we selectively removed MeCP2 function from cholinergic neurons (MeCP2 ChAT KO), which recapitulated the cardiac rhythm abnormalities, hypothermia, and early death seen in RTT male mice. Conversely, restoring MeCP2 only in cholinergic neurons rescued these phenotypes. Thus, MeCP2 in cholinergic neurons is necessary and sufficient for autonomic cardiac control, thermoregulation, and survival, and targeting the overactive parasympathetic system may be a useful therapeutic strategy to prevent sudden unexpected death in RTT.
Jan and Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.|Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, USA.
José A
JA
Herrera
Jan and Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.
Christopher S
CS
Ward
Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, USA.|Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA.|Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX, USA.
Xander H T
XH
Wehrens
Jan and Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.|Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, USA.|Molecular Physiology and Biophysics, Neuroscience Human and Molecular Genetics Pediatrics, Baylor College of Medicine, Houston, TX, USA.
Jeffrey L
JL
Neul
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D001285:Atropine / Q000378:metabolism; D059329:Cholinergic Neurons / Q000378:metabolism* / Q000473:pathology; D016757:Death, Sudden, Cardiac / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D006321:Heart / Q000503:physiopathology; D008297:Male; D051783:Methyl-CpG-Binding Protein 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010275:Parasympathetic Nervous System / Q000473:pathology; D010641:Phenotype; D015518:Rett Syndrome / Q000235:genetics / Q000378:metabolism / Q000473:pathology
C497393:Mecp2 protein, mouse; D051783:Methyl-CpG-Binding Protein 2; D001285:Atropine