每種組織均是透過不同細胞的排列組合而成，因此細胞的型態對於組織再生、分化和傷口癒而言是極為重要的議題。許多種不同的形態控制機制會互相協同控制組織的型態，包括局部性的改變如，貼附點的複雜度、細胞型狀與細胞增生等等。特別是細胞貼附大小與數目的改變也同樣會調控組織分開或是堆疊，細胞貼附大小與數目主要是受到細胞內張力影響。細胞會透過貼附點將細胞內部的機械力量由張力絲傳遞至細胞外部，同時並利用微管維持細胞結構的穩定。本研究將利用牽張衍架模型探討貼附點的複雜度與細胞骨架的結構改變，對於細胞型態的影響。本研究選擇四種型態各異的細胞，探討肌纖維母細胞(C2C12)、纖維母細胞 (NIH 3T3)、內皮細胞 (BAEC)和上皮細胞 (MDCK)型態各異的原因。此四種細胞未貼附時的細胞直徑差異不大，然而，經過三小時的貼附後，發現細胞面積由大到小為纖維母細胞，肌纖維母細胞，內皮細胞和上皮細胞。而肌纖維母細胞與上皮細胞的長寬比較小，纖維母細胞與內皮細胞則反之。不同的細胞也具有不同數目的貼附點位，內皮細胞最高、肌纖維母細胞次之，上皮細胞最低。此外，上皮細胞的貼附點幾乎都出現在細胞周圍，不同於肌纖維母細胞和內皮細胞，其貼附點均勻分布在細胞內部。而利用活體細胞影像技術發現，不同的細胞具有不同的攤附速度，內皮細胞的攤附速度最快，肌纖維母細胞與上皮細胞次之。利用電腦模擬的結果發現，均與張力絲和微管內所分佈的能量有關。因為肌纖維母細胞張力絲內的應變能量較高，故需要融合貼附點增加張力絲的機械強度，避免因能量過高而導致張力絲結構不穩定，更因為需要更多的張力絲，肌纖維母細胞同時需活化更多的貼附蛋白。對上皮細胞而言，貼附點較少，細胞的高度較高。而電腦模擬則發現，較少的貼附點除了會讓細胞高度較高外，微管的應變能量對於細胞高度較高的上皮細胞結構的穩定更顯重要。總結而言，細胞的形態主要與細胞骨架內的能量分部有關，進而調控貼附點的複雜度與牽引力量的大小。

Cell morphology played an important role in tissue regeneration, differentiation and wound healing. During epithelial-mesenchymal transition (EMT) process, cell morphology changes dramatically by altering force balance between extracellular matrix (ECM) and cytoskeletons via focal adhesions (FAs). However, what the force and tension pattern change in cytoskeleton in relation to different morphology was still unknown. The objective of this study was to study how FAs complexity and cytoskeletal architectures influence cell morphology.
To simulate each step of EMT, the fibroblast (NIH 3T3), myofibroblast (C2C12), endothelial cell (BAEC), and epithelial cell (MDCK) were employed in current study. The cell spreading area and aspect ratio were measured for distinguishing the variance of cell morphology. Results indicated the MDCK and C2C12 cells have circular shape and BAEC and NIH 3T3 cells have polygon geometry. By Immuno-fluorescence staining of focal adhesion kinase (FAK), the number and size of FAs per cell were also found to be different among these cells. The plasmid of green fluorescent protein of FAK (GFP-FAK) was transfected into cells, then the distribution of FAs was observed by living cell image. The dynamics of FAs displayed different patterns in different cells. Beside, the measures of each single FA area in 20, 30, 40, 50 and 60 min for each cell type indicate FAs in C2C12 but not BAEC and MDCK enlarged during cell spreading. The cytoskeleton tensegrity model was employed to simulate the dynamics of intracellular force distribution and total stored energy from the FAs coordinates of GFP-FAK during cell spreading. The total energy in stress fiber increased with increasing spreading area. However, less number of FAs in MDCK caused decreased strain energy stored in microtubules and limited the spreading area.
In conclusion, the complexity of FAs might influence cell morphology by altering the spreading area through the energy stored in cytoskeleton. On the other words, cells with different FAs distribution and cytoskeletal arrangement reflected distinct energy patterns and resulted in different architectures in constructing elements for various tissues.

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