We had a new factor in hand and I called it differentiation inhibiting activity (DIA) (Smith & Hooper, 1987).
No coactivation of inspiratory (PS or DIA) and expiratory activity (ABD) was observed either in ERt (Fig. 2) or in ERg [ 4, 5].
Direct interactions of RhoA with mDia1 and mDia2 have been demonstrated in mouse cells as well as Src kinase/Dia interaction, indicating Rho-Dia-Src cooperative activity in the regulation of actin dynamics [21].
Apical localization and activity of Dia are at the core of restricting F-actin formation to the correct membrane domain.
Thus, future studies will be required to further decipher the microtubule stabilizing activity of Dia proteins in the context of a living animal.
Despite increasing in vitro evidence, a physiological role of the microtubule stabilizing activity of Dia proteins has not yet been found in vivo.
Most importantly, the FH1 domain binds Profilin, - which is required for the elongation activity of Dia, albeit not for nucleation., Among the interactors of the FH1 domain are proteins with SH3 domains, such as the F-BAR protein Cip4/Toca-1, the I-BAR protein IRSp53, and the Dia interacting protein DIP/Wish.
Conversely, increased MYB expression overcomes the pro-apoptotic activity of higher DIA concentrations.
Inhibition of Rho signalling by inhibition of Rho-associated kinase (ROCK) and myosin, or transfection of dominant-negative Dia, did not inhibit ZONAB activity (data not shown).
We suggest that DIAs induce pro-apoptotic signals that, at normal differentiation-inducing concentrations, are countered by MYB activity, whereas either increased DIA concentrations and hence stronger apoptotic signaling, or reduced MYB activity leads to apoptosis.
