June 27, 2011 - Nuclear Actin presented by Lindsay

When: June 27, 2011 10:30am
Where: Physics 377
Presenter: Lindsay Moore (Erez Braun's lab, physics)
Link to paper: http://genesdev.cshlp.org/content/25/9/946.full.pdf+html
background reading: http://cshperspectives.cshlp.org/content/2/4/a000620.long

Nuclear actin polymerization is required for transcriptional reprogramming of Oct4by oocytes

1. Kei Miyamoto, 
2. Vincent Pasque, 
3. Jerome Jullien and 
4. John B. Gurdon

1. Wellcome Trust, Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, United Kingdom

1. Amphibian oocytes can rapidly and efficiently reprogram the transcription of transplanted somatic nuclei. To explore the factors and mechanisms involved, we focused on nuclear actin, an especially abundant component of the oocyte's nucleus (the germinal vesicle). The existence and significance of nuclear actin has long been debated. Here, we found that nuclear actin polymerization plays an essential part in the transcriptional reactivation of the pluripotency gene Oct4(also known as Pou5f1). We also found that an actin signaling protein, Toca-1, enhances Oct4 reactivation by regulating nuclear actin polymerization. Toca-1overexpression has an effect on the chromatin state of transplanted nuclei, including the enhanced binding of nuclear actin to gene regulatory regions. This is the first report showing that naturally stored actin in an oocyte nucleus helps transcriptional reprogramming in a polymerization-dependent manner.