蛋白質精胺酸甲基化為一轉譯後修飾，和其相關的細胞功能包括訊息傳遞、蛋白
質胞內定位分布、DNA 修補以及轉錄調控等。我們在胚胎發育研究的模式生物斑馬魚
中找到這些基因的異種同源基因，因此在本計畫中我們以斑馬魚為模式生物系統來闡
析第一型PRMT。我們選擇最主要表現的PRMT1，及其同種同源基因PRMT8 來研究。
我們已研究各種PRMT 於斑馬魚不同發育階段的表達，並已利用morpholino 寡核苷酸
(MO)來抑制zprmt1 及zprmt8 基因表現；我們觀察zprmt1 knock-down 胚胎早期變化，
可見到其畸形率極嚴重程度隨劑量增加的情形。胚胎畸形包含體型彎曲、體軸變短、
脊椎彎曲、卵黃形狀改變、發育遲緩等。斑馬魚zprmt1 morphant 的胚胎的確出現PRMT1
蛋白質表現量下降，以及已知PRMT1 受質如組蛋白H4 的R3 殘基上的精胺酸甲基量
降低等情形。此外另一個斑馬魚精胺酸甲基轉移脢PRMT8 的研究，zprmt8 knock-down
胚胎早期也有體型彎曲、體軸縮短、心包膜嚴重水腫等變化。我們也已建構好不受
MO knock-down 之突變且可表達zprmt1 及zprmt8 的質體，並表達出各mRNA，以注
射回mRNA 是否能彌補缺陷，研究這些演化上相關的PRMT 基因是否功能上可以部分
互補。此外甲基接受蛋白基因在斑馬魚系統中分析也配合進行中。本計劃研究結果對
這幾種甲基轉移脢提供寶貴資訊。
Protein arginine methylation has become one of the most intensively studied
posttranslational modification for cell signaling, protein localization, DNA repair and
transcriptional regulation. Protein arginine methyltransferase 1 (PRMT1) is the predominant
type I methyltransferase in the mammalian system responsible for protein arginine
methylation involved in various cellular functions. PRMT1 and PRMT8 are highly conserved
with more than 90% sequence identity and are likely to be paralogues in vertebrates.We
studied the expression of prmt1 and prmt8 genes in zebrafish by RT-PCR, whole-mount in
situ hybridization and western blot analyses.We also used morpholino-oliogonucleotides
(MO) to specifically inhibit the expression of these prmt genes in zebrafish to observe the
effects of specific PRMT knockdowns during early developmental stages. PRMT1 protein
level, type I protein arginine methyltransferase activity as well as specific asymmetric
arginine methylation were reduced in the zprmt1 morphants. Detailed marker analyses
revealed defective medial-lateral convergence and anterior-posterior extension of the body
plan and the abnormalities were even serious at the posterior than the anterior part of the
embryo. Furthermore, the prmt8 morphants showed significant shortened body-length,
irregularly bent tails and serious heart edema.We had constructed plasmid to express the
mutated MO-resistant zprmt1 or prmt8 mRNA. Rescue of the phenotypes by co-injection of
different prmt mRNA should confirm the specificity and can help investigate whether the
putative paralogues can complement each other.We also use the zebrafish system to study the
substrate for PRMT. Our results confirm the importance of the methyltransferase in zebrafish
early development and provide valuable insights for protein arginine methylation.
