Role of km23-1 in RhoA/actin-based cell migration

km23-1 was originally identified as a TGFß receptor-interacting protein that plays an important role in TGFß signaling. Moreover, km23-1 is actually part of an ancient superfamily of NTPase-regulatory proteins, widely represented in archaea and bacteria. To further elucidate the function of km23-1, we identified novel protein interacting partners for km23-1 by using tandem affinity purification (TAP) and tandem mass spectrometry (MS). Here we show that km23-1 interacted with a class of proteins involved in actin-based cell motility and modulation of the actin cytoskeleton. We further showed that km23-1 modulates the formation of a highly organized stress fiber network. More significantly, we demonstrated that knockdown (KD) of km23-1 decreased RhoA activation in Mv1Lu epithelial cells. Finally, our results demonstrated for the first time that depletion of km23-1 inhibited cell migration of human colon carcinoma cells (HCCCs) in wound-healing assays. Overall, our findings demonstrate that km23-1 regulates RhoA and motility-associated actin modulating proteins, suggesting that km23-1 may represent a novel target for anti-metastatic therapy.

► We identified several motility-related km23-1-interacting proteins.
► km23-1 overexpression increases actin stress fiber formation in epithelial cells.
► Depletion of km23-1 inhibits RhoA activation in epithelial cells.
► km23-1 depletion inhibits cell migration of human colon carcinoma cells.