Expression of Id2 and Id3 mRNA in human lymphocytes.
Helix-loop-helix (HLH) transcription factors are involved in cellular growth and differentiation. The Id (inhibitor of DNA binding and differentiation) HLH proteins, in a dominantly negative fashion, regulate transcriptional activities of basic HLH proteins. We examined by northern hybridization the expression of Id2 and Id3 mRNA in human leukemia/lymphoma lines and patient samples, as well as resting and activated normal human lymphocytes from peripheral blood (PBL). The Id2 mRNA was abundantly expressed in 5/12 T-cell and 3/4 B-cell lines, and Id3 mRNA was detected in 4/12 T-cell and 3/4 B-cell lines. Interestingly, Id2, but not Id3, mRNA was strongly expressed in 4/5 T-cell lines infected with human T-cell leukemia virus type I (HTLV-I) (ATL-1k, MT-2, S-LB1) and type II (Mo). Another unexpected finding was that T-cell leukemias and T-cell lines often expressed either Id2 or Id3 mRNA. In addition, resting PBL constitutively expressed prominent levels of Id2 mRNA, but not Id3 mRNA. Upon PHA-stimulation, Id2 expression decreased and Id3 levels increased with biphasic kinetics. Taken together, our studies revealed three unexpected findings which require further analysis: (1) expression of Id2 mRNA is often associated with lymphocytic transformation by HTLV-I or -II; (2) T-cells usually express either Id2 or Id3 mRNA, but B-cells often express both simultaneously; (3) non-dividing, normal PBL express high levels of Id2 and no Id3 mRNA; and with the onset of cellular proliferation, levels of Id2 mRNA decrease while levels of Id3 mRNA increase, suggesting that regulation of expression of these closely related genes is disparate.
Ishiguro
A
A
Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine 90048, USA.
Spirin
K
K
Shiohara
M
M
Tobler
A
A
Norton
J D
JD
Rigolet
M
M
Shimbo
T
T
Koeffler
H P
HP
D001402:B-Lymphocytes / Q000378:metabolism; D015152:Blotting, Northern; D002472:Cell Transformation, Viral / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D018257:Helix-Loop-Helix Motifs / Q000235:genetics; D015368:Human T-lymphotropic virus 1; D015367:Human T-lymphotropic virus 2; D006801:Humans; D051797:Inhibitor of Differentiation Protein 2; D051796:Inhibitor of Differentiation Proteins; D007938:Leukemia / Q000235:genetics / Q000378:metabolism; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000378:metabolism*; D008223:Lymphoma / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins; D012333:RNA, Messenger / Q000378:metabolism*; D012097:Repressor Proteins; D013601:T-Lymphocytes / Q000378:metabolism / Q000821:virology; D014157:Transcription Factors / Q000235:genetics*
D004268:DNA-Binding Proteins; C497450:ID2 protein, human; D051797:Inhibitor of Differentiation Protein 2; D051796:Inhibitor of Differentiation Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; C075640:ID3 protein, human