Fred A. Litwin Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Toronto, Ontario, Canada.
PLoS One. 2013 May 21;8(5):e62468. doi: 10.1371/journal.pone.0062468. Print 2013.
Mutations in BRCA1 and BRCA2 are responsible for a large proportion of breast-ovarian cancer families. Protein-truncating mutations have been effectively used in the clinical management of familial breast cancer due to their deleterious impact on protein function. However, the majority of missense variants identified throughout the genes continue to pose an obstacle for predictive informative testing due to low frequency and lack of information on how they affect BRCA1/2 function. Phosphorylation of BRCA1 and BRCA2 play an important role in their function as regulators of DNA repair, transcription and cell cycle in response to DNA damage but whether missense variants of uncertain significance (VUS) are able to disrupt this important process is not known. Here we employed a novel approach using NetworKIN which predicts in vivo kinase-substrate relationship, and evolutionary conservation algorithms SIFT, PolyPhen and Align-GVGD. We evaluated whether 191 BRCA1 and 43 BRCA2 VUS from the Breast Cancer Information Core (BIC) database can functionally alter the consensus phosphorylation motifs and abolish kinase recognition and binding to sites known to be phosphorylated in vivo. Our results show that 13.09% (25/191) BRCA1 and 13.95% (6/43) BRCA2 VUS altered the phosphorylation of BRCA1 and BRCA2. We highlight six BRCA1 (K309T, S632N, S1143F, Q1144H, Q1281P, S1542C) and three BRCA2 (S196I, T207A, P3292L) VUS as potentially clinically significant. These occurred rarely (n<2 in BIC), mutated evolutionarily conserved residues and abolished kinase binding to motifs established in the literature involved in DNA repair, cell cycle regulation, transcription or response to DNA damage. Additionally in vivo phosphorylation sites identified via through-put methods are also affected by VUS and are attractive targets for studying their biological and functional significance. We propose that rare VUS affecting phosphorylation may be a novel and important mechanism for which BRCA1 and BRCA2 functions are disrupted in breast cancer.
BRCA1 和 BRCA2 中的突变导致了很大一部分乳腺癌-卵巢癌家族。由于对蛋白质功能具有有害影响，蛋白截断突变已被有效地用于家族性乳腺癌的临床管理中。然而，由于频率低且缺乏关于它们如何影响 BRCA1/2 功能的信息，整个基因中鉴定出的大多数错义变体仍然是预测信息性测试的障碍。BRCA1 和 BRCA2 的磷酸化在其功能中起着重要作用，作为对 DNA 损伤的 DNA 修复、转录和细胞周期的调节剂，但不确定意义的错义变体（VUS）是否能够破坏这一重要过程尚不清楚。在这里，我们使用 NetworKIN 采用了一种新方法，该方法预测体内激酶-底物关系，并使用 SIFT、PolyPhen 和 Align-GVGD 等进化保守性算法。我们评估了来自乳腺癌信息核心（BIC）数据库的 191 个 BRCA1 和 43 个 BRCA2 VUS 是否能够在功能上改变共识磷酸化基序，并消除激酶识别和结合体内已知磷酸化的位点。我们的结果表明，13.09%（25/191）的 BRCA1 和 13.95%（6/43）的 BRCA2 VUS 改变了 BRCA1 和 BRCA2 的磷酸化。我们重点介绍了六个 BRCA1（K309T、S632N、S1143F、Q1144H、Q1281P、S1542C）和三个 BRCA2（S196I、T207A、P3292L）VUS，它们可能具有临床意义。这些 VUS 很少见（BIC 中<2），突变了进化保守的残基，并消除了激酶与文献中建立的涉及 DNA 修复、细胞周期调控、转录或 DNA 损伤反应的基序的结合。此外，通过高通量方法鉴定的体内磷酸化位点也受 VUS 影响，是研究其生物学和功能意义的有吸引力的靶点。我们提出，影响磷酸化的罕见 VUS 可能是 BRCA1 和 BRCA2 功能在乳腺癌中被破坏的一种新的重要机制。
