Mutations in DNA methyltransferase DNMT3B in ICF syndrome affect its regulation by DNMT3L.
Deficiency in DNA methyltransferase DNMT3B causes a recessive human disorder characterized by immunodeficiency, centromeric instability and facial anomalies (ICF) in association with defects in genomic methylation. The majority of ICF mutations are single amino acid substitutions in the conserved catalytic domain of DNMT3B, which are believed to impair its enzymatic activity directly. The establishment of intact genomic methylation patterns in development requires a fine regulation of the de novo methylation activity of the two related methyltransferases DNMT3A and DNMT3B by regulatory factors including DNMT3L which has a stimulatory effect. Here, we show that two DNMT3B mutant proteins with ICF-causing substitution (A766P and R840Q) displayed a methylation activity similar to the wild-type enzyme both in vitro and in vivo. However, their stimulation by DNMT3L was severely compromised due to deficient protein interaction. Our findings suggest that methylation defects in ICF syndrome may also result from impaired stimulation of DNMT3B activity by DNMT3L or other unknown regulatory factors as well as from a weakened basal catalytic activity of the mutant DNMT3B protein per se.
Xie
Zheng-Hua
ZH
The State Key Laboratory of Molecular Biology, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.
Huang
Yan-Nv
YN
Chen
Zhao-Xia
ZX
Riggs
Arthur D
AD
Ding
Jian-Ping
JP
Gowher
Humaira
H
Jeltsch
Albert
A
Sasaki
Hiroyuki
H
Hata
Kenichiro
K
Xu
Guo-Liang
GL
D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D020134:Catalytic Domain / Q000235:genetics; D002460:Cell Line; D043171:Chromosomal Instability / Q000235:genetics*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D019175:DNA Methylation; D005147:Facial Bones / Q000002:abnormalities*; D006801:Humans; D007527:Isoenzymes / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D041681:NIH 3T3 Cells; D013577:Syndrome; D000097584:DNA Methyltransferase 3B
D004248:DNA (Cytosine-5-)-Methyltransferases; D007527:Isoenzymes; D000097584:DNA Methyltransferase 3B; C412484:DNMT3L protein, human