The association (top) of myosin VI (green) and RNA polymerase II (red) is lost when transcription is disrupted (bottom).

Transcription gets a boost from myosin VI, according to findings from Sarah Vreugde (DIBIT Scientific Institute, Milano, Italy) and colleagues. The motor might drag genes into transcription neighborhoods.

While trying to understand the function of myosin VI, Vreugde noticed that its localization pattern looked much like that of RNA polymerase II. The authors then showed an association between the motor and polymerase that depends on ongoing transcription.

By cross-linking myosin VI to chromatin, the group identified several genes at which the motor is found. The mRNA levels of these genes decreased when myosin VI levels were reduced. Vreugde next hopes to inhibit just the nuclear pool of myosin VI and then do genome-wide analyses to identify more affected genes.

Assuming its influence is widespread, the motor might spool the DNA past aggregates of RNA polymerases or recruit stretches of DNA to transcription factories. “DNA recruitment to transcription factories would be heavy work,” says Vreugde. “But myosin is well-suited to accomplish that.”

Whether its unusual preference to move toward actin minus ends helps myosin VI at all is unclear, as the polarity of the nuclear actin network is not known and probably dynamic. The only other known nuclear myosin, myosin I, is plus-end directed but still enhances transcription by all the RNA polymerases.

Reference:

Vreugde, S., et al.
2006
.
Mol. Cell.
23
:
749
–755.