Intranuclear targeting of AML/CBFalpha regulatory factors to nuclear matrix-associated transcriptional domains.

Zeng C, McNeil S, Pockwinse S, Nickerson J, Shopland L, Lawrence JB, Penman S, Hiebert S, Lian JB, van Wijnen AJ, Stein JL, Stein GS
Proc Natl Acad Sci U S A. 1998 95 (4): 1585-9

PMID: 9465059 · PMCID: PMC19104 · DOI:10.1073/pnas.95.4.1585

The AML/CBFalpha runt transcription factors are key regulators of hematopoietic and bone tissue-specific gene expression. These factors contain a 31-amino acid nuclear matrix targeting signal that supports association with the nuclear matrix. We determined that the AML/CBFalpha factors must bind to the nuclear matrix to exert control of transcription. Fusing the nuclear matrix targeting signal to the GAL4 DNA binding domain transactivates a genomically integrated GAL4 responsive reporter gene. These data suggest that AML/CBFalpha must associate with the nuclear matrix to effect transcription. We used fluorescence labeling of epitope-tagged AML-1B (CBFA2) to show it colocalizes with a subset of hyperphosphorylated RNA polymerase II molecules concentrated in foci and linked to the nuclear matrix. This association of AML-1B with RNA polymerase II requires active transcription and a functional DNA binding domain. The nuclear matrix domains that contain AML-1B are distinct from SC35 RNA processing domains. Our results suggest two of the requirements for AML-dependent transcription initiation by RNA polymerase II are association of AML-1B with the nuclear matrix together with specific binding of AML to gene promoters.

MeSH Terms (13)

Cell Compartmentation Core Binding Factor Alpha 2 Subunit DNA-Binding Proteins HeLa Cells Humans Microscopy, Fluorescence Nuclear Matrix Proto-Oncogene Proteins RNA Polymerase II Transcription, Genetic Transcriptional Activation Transcription Factors Transfection

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