2020-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/648123摘要：成年哺乳動物心臟缺乏再生能力，是造成心肌受損後無法完全恢復正常功能的重要 因素，也是許多不同心血管疾病最後導致心臟衰竭發生的關鍵。因為心肌細胞缺乏 再生能力，成年哺乳動物心臟在受損後，無法再生心肌細胞，而增生的纖維組織會 取代心肌細胞受傷死亡後留下的空間，造成心肌收縮力下降，並導致心室重塑，肥 厚或擴大，進而引發心衰竭甚至死亡。對應於成年哺乳動物無法有效進行心肌再生 ，新生小鼠及人類新生兒則具有心臟再生能力，可以幾乎完全修復受損的心臟；然 而，這樣的心臟再生能力在出生後不久就會逐漸消失。因此，找出啟動新生哺乳動 物心肌細胞再生的”分子開關”，是促進成人心臟再生能力的重要關鍵，也是恢復受 損心臟功能的根本治療手段。 我們實驗室利用次世代RNA定序(RNASeq)分析出生一天及三天(P1 & P3)新生小鼠 及成年小鼠的心肌細胞基因表現，發現神經鈣粘蛋白(N-Cadherin)在調節心肌細胞 複製與再生上具有重要功能。N-Cadherin在心肌細胞的表現量，與細胞週期及細 胞增生相關的基因表現量呈現高度正相關，同時N-Cadherin的表現量隨著年齡增 加而遞減，成鼠心肌表達量僅剩P1新生小鼠的1/4，與心臟細胞再生能力隨年齡增 加而下降一致。新生小鼠心臟N-Cadherin表達量，在心尖切除後會顯著上升，在 心尖切除進行修複的部位最高，而在遠離受傷區域表達量則較低，與新生小鼠心肌 受損後心肌細胞再生活性的分佈(切除處高，遠離區域低)一致。最重要的是，在 P1新生小鼠心肌細胞中敲低N-Cadherin，能夠抑制心肌細胞複製增生的能力，及 其細胞週期基因的表達；反之，過量表達N-Cadherin則會提升心肌細胞的增生能 力並使細胞週期基因表達上升。這些實驗結果都證明N-Cadherin在調節心肌細胞 複製再生能力上，具有過去從未被發現的重要角色。 本研究計劃的主要目的，在找出N-Cadherin如何影響心肌細胞增生/再生的分子機 轉，同時希望能利用動物實驗驗證N-Cadherin在活體新生小鼠心臟受損後再生的 角色，並測試是否能藉由在心肌梗塞成鼠心臟中過量表達N-Cadherin來促進心肌 細胞再生，進而改善心臟功能；最後，我們將以N-Cadherin結構為基礎，開發促 進心肌細胞再生的大分子藥物，測試其於活體動物心肌梗塞後促進心肌細胞複製再 生的效益，並作為心臟衰竭的新型治療策略。<br> Abstract: Heart failure, irrespective of the underlying etiology, can be attributed to the limited regeneration capacity of adult mammalian cardiomyocytes (CM), where lost CM following injury are replaced by fibrotic scar, leading to impaired contractile function, maladaptive remodeling and ultimately, heart failure and death. While the regenerative response in adult mammalian heart is limited, it is widely recognized that neonatal mouse and human hearts can fully regenerate in response to injury, albeit this regenerating capacity declines rapidly after birth. Identifying the “molecular switches” triggering cardiomyocyte regeneration in neonatal mammalian heart, therefore, is the key to develop novel therapeutics to promote cardiac regeneration and to restore myocardial function in the failing heart. Exploiting next-gen RNA sequencing (RNASeq) in CM isolated from neonatal (P1 & P3) and adult mouse heart, we identified N-Cadherin, a member of Ca2+- dependent cell adhesion protein cadherin superfamily, as a potential novel regulator of CM proliferation/regeneration. N-Cadherin expression exhibits strong correlation with cell cycle- and proliferation-related protein genes and its expression levels show an age-dependent reduction, with 75% less N-Cadherin in adult, than in P1 neonatal, CM. Myocardial N-Cadherin expression is upregulated in neonatal mouse heart in response to apical resection, highest in the apical zone and decreased gradually toward the remote zone, which correlates strongly with the CM regenerative/proliferative activity in neonatal heart following injury. Importantly, knocking down N-Cadherin reduced, whereas overexpression of N-Cadherin increased, the proliferation activity of neonatal CM. Taken together, these data strongly suggest a critical yet previously unrecognized role of N-Cadherin in CM proliferation and regeneration. The goals of this proposal are (1) to determine the molecular mechanisms via which NCadherin modulate CM proliferative/regenerative activity, (2) to understand the in vivo contribution of N-Cadherin to cardiac regeneration in neonatal heart following injury, (3) to test the hypothesis that forced expression of N-Cadherin in vivo can promote cardiac regeneration and preserve contractile function in adult mouse heart after myocardial infarction and (4) to develop N-Cadherin-mimic agents as a novel therapeutic approach to promote cardiac regeneration.心肌再生神經鈣粘蛋白cardiac regenerationN-cadherin