Muscle Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy.
PLoS One. 2011;6(10):e25519. doi: 10.1371/journal.pone.0025519. Epub 2011 Oct 10.
Ankrd2 (also known as Arpp) together with Ankrd1/CARP and DARP are members of the MARP mechanosensing proteins that form a complex with titin (N2A)/calpain 3 protease/myopalladin. In muscle, Ankrd2 is located in the I-band of the sarcomere and moves to the nucleus of adjacent myofibers on muscle injury. In myoblasts it is predominantly in the nucleus and on differentiation shifts from the nucleus to the cytoplasm. In agreement with its role as a sensor it interacts both with sarcomeric proteins and transcription factors.
METHODOLOGY/PRINCIPAL FINDINGS: Expression profiling of endogenous Ankrd2 silenced in human myotubes was undertaken to elucidate its role as an intermediary in cell signaling pathways. Silencing Ankrd2 expression altered the expression of genes involved in both intercellular communication (cytokine-cytokine receptor interaction, endocytosis, focal adhesion, tight junction, gap junction and regulation of the actin cytoskeleton) and intracellular communication (calcium, insulin, MAPK, p53, TGF-β and Wnt signaling). The significance of Ankrd2 in cell signaling was strengthened by the fact that we were able to show for the first time that Nkx2.5 and p53 are upstream effectors of the Ankrd2 gene and that Ankrd1/CARP, another MARP member, can modulate the transcriptional ability of MyoD on the Ankrd2 promoter. Another novel finding was the interaction between Ankrd2 and proteins with PDZ and SH3 domains, further supporting its role in signaling. It is noteworthy that we demonstrated that transcription factors PAX6, LHX2, NFIL3 and MECP2, were able to bind both the Ankrd2 protein and its promoter indicating the presence of a regulatory feedback loop mechanism.
CONCLUSIONS/SIGNIFICANCE: In conclusion we demonstrate that Ankrd2 is a potent regulator in muscle cells affecting a multitude of pathways and processes.
ANKRD2（也称为 ARPP）与 ANKRD1/CARP 和 DARP 一起是 MARP 机械感觉蛋白的成员，与肌联蛋白（N2A）/钙蛋白酶 3 蛋白酶/肌联蛋白结合形成复合物。在肌肉中，ANKRD2 位于肌节的 I 带，在肌肉损伤时移动到相邻肌纤维的核内。在成肌细胞中，它主要位于核内，在分化过程中从核内转移到细胞质。与其作为传感器的作用一致，它与肌节蛋白和转录因子相互作用。
方法/主要发现：为了阐明其作为细胞信号通路中介物的作用，对人肌管中内源性 ANKRD2 沉默的表达谱进行了研究。沉默 ANKRD2 表达改变了参与细胞间通讯（细胞因子-细胞因子受体相互作用、内吞作用、粘着斑、紧密连接、缝隙连接和肌动蛋白细胞骨架调节）和细胞内通讯（钙、胰岛素、MAPK、p53、TGF-β和 Wnt 信号）的基因的表达。ANKRD2 在细胞信号中的重要性得到了加强，因为我们首次能够证明 Nkx2.5 和 p53 是 ANKRD2 基因的上游效应物，另一个 MARP 成员 ANKRD1/CARP 可以调节 MyoD 对 ANKRD2 启动子的转录能力。另一个新发现是 ANKRD2 与具有 PDZ 和 SH3 结构域的蛋白质之间的相互作用，进一步支持其在信号转导中的作用。值得注意的是，我们证明转录因子 PAX6、LHX2、NFIL3 和 MECP2 能够结合 ANKRD2 蛋白及其启动子，表明存在调节反馈环机制。
总之，我们证明 ANKRD2 是肌肉细胞中的一种有效调节因子，影响多种途径和过程。
