AFAP 110 MODULATES SIGNALS THAT EFFECT ACTIN FILAMENTS

所有的癌细胞都有一个共同点--它们会改变形状。形态在很大程度上是由细胞骨架的组成成分决定的，如肌动蛋白细丝，而癌基因如Src将改变肌动蛋白细丝的完整性。然而，Src直接影响肌动蛋白细丝结构的机制尚不清楚。Src相关底物AFAP-110(肌动蛋白细丝相关蛋白，110 kDa)最初被认为是Src的SH2/SH3结合伙伴，并被假设为调节Src对肌动蛋白细丝的影响。AFAP-110在改变肌动蛋白细丝完整性方面的作用是通过突变羧基末端的亮氨酸拉链基序来揭示的，这使得AFAP-110能够在体内和体外破坏肌动蛋白细丝。AFAP-110还与片状脂膜和膜褶皱相关，表明在这些结构的形成中可能起到了作用。Src527F的表达会影响AFAP-110的构象，从而激活并使其改变肌动蛋白细丝的完整性。因此，AFAP-110改变肌动蛋白细丝结构的能力可能是可激活的，证据支持p21激活的激酶Pak在这一途径中的潜在作用。我们推测，AFAP-110可以重塑肌动蛋白细丝，以响应由Src和Pak调制的细胞信号，导致肌动蛋白花环、片状脂膜和膜褶皱的形成。这些特定的目标将决定(1)AFAP-110如何影响肌动蛋白细丝的完整性，(2)AFAP-110破坏肌动蛋白细丝是否会影响细胞的形态和运动，(3)AFAP-110如何受到调控，以及(4)来自生长因子、SrC527F或Pak的细胞信号如何影响AFAP-110的结构和功能。这些数据对癌症既重要又相关，因为AFAP-110可以直接调节肌动蛋白细丝的完整性，以响应已知的影响细胞形态和运动性的细胞信号，这是转化和转移的标志。AFAP-110也可能是CSRC激活的人类癌症预后、诊断和治疗的相关治疗靶点和/或分子标志物，例如乳腺癌和结肠癌。

All cancer cells have one thing in common - they change shape. Morphology is largely governed by components of the cytoskeleton, such as actin filaments, and oncogenes like Src will alter actin filament integrity. However, the mechanisms by which Src directly affects actin filament structures are unknown. The Src-associated substrate AFAP-110 (actin filament-associated protein, 110 kDa) was originally characterized as an SH2/SH3 binding partner for Src and has been hypothesized to modulate the effects of Src upon actin filaments. A role for AFAP-110 in altering actin filament integrity was revealed by mutagenesis of a carboxy-terminal leucine zipper motif, which enabled AFAP-110 to disrupt actin filaments in vivo and in vitro. AFAP-110 also associates with lamellipodia and membrane ruffles, indicating a potential role in the formation of these structures. Src527F expression will affect the conformation of AFAP-110, which may activate and enable it to alter actin filament integrity. Thus, the ability of AFAP-110 to alter actin filament structures may be activatable and evidence support a potential role for the p2l-activated kinase Pak in this pathway. We hypothesize that AFAP-110 can remodel actin filaments in response to cellular signals modulated by Src and Pak, resulting in the formation of actin rosettes, lamellipodia and membrane ruffles. The specific aims will determine (1) how AFAP-110 affects actin filament integrity, (2) whether disruption of actin filaments by AFAP-110 can affect cell morphology and motility, (3) how AFAP-110 is regulated and (4) how cellular signals from growth factors, SrC527F or Pak may effect the structure and function of AFAP-110. These data are both important and relevant to cancer, as AFAP-110 may directly modulate actin filament integrity in response to cellular signals known to effect cell morphology and motility, hallmarks of transformation and metastasis. AFAP-110 may also be a relevant therapeutic target and/or a molecular marker for prognosis, diagnosis and treatment of human cancers where cSrc is activated, e.g., breast and colon cancer.