Epigenetic modification of the norepinephrine transporter gene in postural tachycardia syndrome.
OBJECTIVE
The postural tachycardia syndrome (POTS) has multiple symptoms, chief among which are tachycardia, weakness, and recurrent blackouts while standing. Previous research has implicated dysfunction of the norepinephrine transporter. A coding mutation in the norepinephrine transporter gene (SLC6A2) sequence has been reported in 1 family kindred only. The goal of the present study was to further characterize the role and regulation of the SLC6A2 gene in POTS.


RESULTS
Sympathetic nervous system responses to head-up tilt were examined by combining norepinephrine plasma kinetics measurements and muscle sympathetic nerve activity recordings in patients with POTS compared with that in controls. The SLC6A2 gene sequence was investigated in leukocytes from POTS patients and healthy controls using single nucleotide polymorphisms genotyping, bisulphite sequencing, and chromatin immunoprecipitation assays for histone modifications and binding of the transcriptional regulatory complex, methyl-CpG binding protein 2. The expression of norepinephrine transporter was lower in POTS patients compared with healthy volunteers. In the absence of altered SLC6A2 gene sequence or promoter methylation, this reduced expression was directly correlated with chromatin modifications.


CONCLUSIONS
We propose that chromatin-modifying events associated with SLC6A2 gene suppression may constitute a mechanism of POTS.
Baker IDI Heart & Diabetes Institute, The University of Melbourne, Melbourne, Victoria 3004, Australia.
Richard
R
Bayles
K N
KN
Harikrishnan
Elisabeth
E
Lambert
Emma K
EK
Baker
Alex
A
Agrotis
Ling
L
Guo
Jeremy B M
JB
Jowett
Murray
M
Esler
Gavin
G
Lambert
Assam
A
El-Osta
D000328:Adult; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D020869:Gene Expression Profiling; D006439:Hemodynamics; D006801:Humans; D008297:Male; D050484:Norepinephrine Plasma Membrane Transport Proteins / Q000235:genetics*; D011110:Polymorphism, Genetic; D054972:Postural Orthostatic Tachycardia Syndrome / Q000235:genetics* / Q000503:physiopathology; D011401:Promoter Regions, Genetic
D050484:Norepinephrine Plasma Membrane Transport Proteins; C493227:SLC6A2 protein, human