TY - JOUR
T1 - A novel DNMT3B splice variant expressed in tumor and pluripotent cells modulates genomic DNA methylation patterns and displays altered DNA binding
AU - Gopalakrishnan, Suhasni
AU - Van Emburgh, Beth O.
AU - Shan, Jixiu
AU - Su, Zhen
AU - Fields, C. Robert
AU - Vieweg, Johannes
AU - Hamazaki, Takashi
AU - Schwartz, Philip H.
AU - Terada, Naohiro
AU - Robertson, Keith D.
PY - 2009/10
Y1 - 2009/10
N2 - DNA methylation is an epigenetic mark essential for mammalian development, genomic stability, and imprinting. DNA methylation patterns are established and maintained by three DNA methyltransferases: DNMT1, DNMT3A, and DNMT3B. Interestingly, all three DNMTs make use of alternative splicing. DNMT3B has nearly 40 known splice variants expressed in a tissue- and disease-specific manner, but very little is known about the role of these splice variants in modulatingDNMT3B function. We describe here the identification and characterization of a novel alternatively spliced form of DNMT3B lackingexon 5 within the NH2-terminal regulatory domain. This variant, which we term DNMT3B3Δ5 because it is closely related in structure to the ubiquitously expressed DNMT3B3 isoform, is highly expressed in pluripotent cells and brain tissue, is downregulated during differentiation, and is conserved in the mouse. Creation of pluripotent iPS cells from fibroblasts results in marked induction of DNMT3B3Δ5. DNMT3B3Δ5 expression is also altered in human disease, with tumor cell lines displayingelevated or reduced expression depending on their tissue of origin. We then compared the DNA binding and subcellular localization of DNMT3B3Δ5 versus DNMT3B3, revealingthat DNMT3B3Δ5 possessed significantly enhanced DNA binding affinity and displayed an altered nuclear distribution. Finally, ectopic overexpression of DNMT3B3Δ5 resulted in repetitive element hypomethylation and enhanced cell growth in a colony formation assay. Taken together, these results show that DNMT3B3Δ5 may play an important role in stem cell maintenance or differentiation and suggest that sequences encoded by exon 5 influence the functional properties of DNMT3B.
AB - DNA methylation is an epigenetic mark essential for mammalian development, genomic stability, and imprinting. DNA methylation patterns are established and maintained by three DNA methyltransferases: DNMT1, DNMT3A, and DNMT3B. Interestingly, all three DNMTs make use of alternative splicing. DNMT3B has nearly 40 known splice variants expressed in a tissue- and disease-specific manner, but very little is known about the role of these splice variants in modulatingDNMT3B function. We describe here the identification and characterization of a novel alternatively spliced form of DNMT3B lackingexon 5 within the NH2-terminal regulatory domain. This variant, which we term DNMT3B3Δ5 because it is closely related in structure to the ubiquitously expressed DNMT3B3 isoform, is highly expressed in pluripotent cells and brain tissue, is downregulated during differentiation, and is conserved in the mouse. Creation of pluripotent iPS cells from fibroblasts results in marked induction of DNMT3B3Δ5. DNMT3B3Δ5 expression is also altered in human disease, with tumor cell lines displayingelevated or reduced expression depending on their tissue of origin. We then compared the DNA binding and subcellular localization of DNMT3B3Δ5 versus DNMT3B3, revealingthat DNMT3B3Δ5 possessed significantly enhanced DNA binding affinity and displayed an altered nuclear distribution. Finally, ectopic overexpression of DNMT3B3Δ5 resulted in repetitive element hypomethylation and enhanced cell growth in a colony formation assay. Taken together, these results show that DNMT3B3Δ5 may play an important role in stem cell maintenance or differentiation and suggest that sequences encoded by exon 5 influence the functional properties of DNMT3B.
UR - http://www.scopus.com/inward/record.url?scp=72449197125&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=72449197125&partnerID=8YFLogxK
U2 - 10.1158/1541-7786.MCR-09-0018
DO - 10.1158/1541-7786.MCR-09-0018
M3 - Article
C2 - 19825994
AN - SCOPUS:72449197125
SN - 1541-7786
VL - 7
SP - 1622
EP - 1634
JO - Molecular Cancer Research
JF - Molecular Cancer Research
IS - 10
ER -