Dynein light chain rp3 acts as a nuclear matrix-associated transcriptional modulator in a dynein-independent pathway.
Cytoplasmic dynein is a motor protein complex involved in microtubule-based cargo movement. Previous biochemical evidence suggests that dynein light chain subunits also exist outside the dynein complex. Here we show that the dynein light chain rp3 is present in both the cytoplasm and the nucleus. Nuclear rp3 binds to and assembles with the transcription factor SATB1 at nuclear matrix-associated structures. Dynein intermediate chain was also detected in the nucleus, but it was dispensable for the rp3-SATB1 interaction. SATB1 facilitates the nuclear localization of rp3, whereas rp3 and dynein motor activity are not essential for nuclear accumulation of SATB1. The nuclear rp3-SATB1 protein complex is assembled with a DNA element of the matrix attachment region of the Bcl2 gene. Finally, rp3 is involved in SATB1-mediated gene repression of Bcl2. Our data provide evidence that dynein subunit rp3 has functions independent of the dynein motor.
Yeh
Ting-Yu
TY
Department of Ophthalmology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA.
Chuang
Jen-Zen
JZ
Sung
Ching-Hwa
CH
D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology; D004398:Dyneins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D036961:Matrix Attachment Region Binding Proteins / Q000378:metabolism*; D015530:Nuclear Matrix / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D036961:Matrix Attachment Region Binding Proteins; D009687:Nuclear Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; C076189:SATB1 protein, human; D014157:Transcription Factors; D004398:Dyneins