中心體是由兩互相垂直的中心粒以及圍繞在周圍的中心粒周圍物質(PCM)所組成。中心體在細胞分裂中扮演著很重要的角色。然而不正常的中心體數目異常可能增加基因組不穩定性而促進腫瘤的生成。中心粒衛星蛋白 (centriolar satellite)包含許多中心體蛋白並且圍繞在中心體附近。中心粒衛星蛋白主要是由PCM-1所構成的，PCM-1在中心粒衛星蛋白中的功能是作為支架蛋白來組裝其他的中心粒衛星蛋白。從先前的研究發現在長期的複製壓力下會透過中心粒衛星蛋白remodeling而導致中心體數目異常。因此，人們覺得在長期複製壓力下，PCM-1可能在導致中心體數目異常中扮演著角色。在本篇研究中，我們利用hydroxyurea (HU)來研究PCM-1在長期複製壓力下的作用為何。我們發現在長期複製壓力下會誘導細胞中心體數目異常以及PCM-1 remodeling。為了進一步確認是否PCM-1參與在長期複製壓力下所誘導的中心體數目異常，我們利用了藥理以及遺傳學的方法來抑制PCM-1 remodeling。我們的結果顯示破壞 PCM-1 remodeling對於中心體數目異常沒有影響。然而，抑制中心體數目異常降低PCM-1 remodeling，這也說明中心體數目異常可能有助於PCM-1 remodeling。接著，我們探討PCM-1在長期複製壓力之下對於DNA損傷反應有何影響。在HU的處理下活化PI3K-like kinases (ATM、ATR 和 DNA-PK)。有趣的是，在長期複製壓力下，PCM-1的缺失會降低這些激酶的活化。此外，在長期複製壓力下會誘導細胞自噬產生並且PCM-1的缺失會抑制因HU所誘導的細胞自噬。另外，在HU的處理下，PCM-1的缺失會誘導細胞死亡。總結而言，在本篇實驗中我們認為在長期複製壓力下，PCM-1調控DNA損傷反應來維持細胞存活。

The centrosome consists of two orthogonally arranged centrioles and surrounded by electron-dense pericentriolar material (PCM). Centrosome plays an important role in cell division. Consequently, abnormal centrosome amplification which may facilitate tumorigenesis by increasing genomic instability. Centriolar satellites contain numerous proteins that are located around the centrosome. The major component of centriolar satellite protein is called PCM-1, which functions as a scaffold protein in the centriolar satellites for the assembly of other centriolar satellites proteins. Previous studies show that prolonged replication stress causes centrosome amplification via centriolar satellites remodeling. Thus, people suggest PCM-1 might play a role in centrosome amplification under prolonged replication stress. Here, we investigated the role of PCM-1 in centrosome amplification under prolonged replication stress by using hydroxyurea (HU) treatment. Prolonged replication stress-induced centrosome amplification and PCM-1 remodeling. To confirm whether PCM-1 participates in prolonged replication stress-induced centrosome amplification, we used pharmacological and genetic approaches to inhibit PCM-1 remodeling. Our results showed that disruption of PCM-1 remodeling had no effect on the centrosome amplification. However, inhibition of centrosome amplification reduced PCM-1 remodeling suggesting that centrosome amplification might contribute to PCM-1 remodeling. Then, we investigated the role of PCM-1 in DNA damage response under prolonged replication stress. PI3K-like kinase, ATM, ATR, and DNA-PK, were activated by HU treatment. Interestingly, depletion of PCM-1 decreased the activation of these kinases upon prolonged replication stress. Besides, autophagy was activated by prolonged replication stress, and depletion of PCM-1 inhibited HU-induced autophagy. Furthermore, depletion of PCM-1 induced cell death upon HU treatment. In conclusion, this study suggests that PCM-1 regulates DNA damage response signaling to maintain cell survival during prolonged replication stress.

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