不同的 CD44 剪接变异体对侧支动脉生长的影响不同。

Laboratory of Experimental Cardiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.

Curr Vasc Pharmacol. 2013 Jan;11(1):13-20.

OBJECTIVE

Lack of the adhesion molecule CD44 reduces collateral artery growth (arteriogenesis) in a murine hindlimb model. CD44 function is influenced by expression of 10 alternatively spliced exons (v1-v10), with unknown effects on arteriogenesis. As the variant exon CD44v3 binds heparan sulphate and facilitates preservation of growth factors, we hypothesized that the variably spliced exon region of CD44, especially exon CD44v3, is involved in arteriogenesis.

MATERIALS AND METHODS

The right femoral artery of C57BL/6J-mice was ligated and tissue was processed for histological and qPCR analysis of CD44-isoform expression. Microsphere perfusion measurements were performed in mice lacking the variably spliced exon region (CD44s knock-in mice), and in knock-in strains with specific isoform expression (CD44v3-10 and CD44v4-10), as well as in double knock-in mice, expressing CD44v3-10 and CD44s.

RESULTS

Expression of total CD44 and CD44v3 mRNA following femoral artery ligation was increased, accompanied by increased mRNA levels of the CD44-relevant splicing factors Tra2-beta1 and SRm160. CD44v3-expression was limited to the vessel wall of growing collateral arteries. Perfusion restoration was significantly reduced in mice lacking the variably spliced exon region (CD44s):20.1 ± 1.3%, compared to the background strain: 57.3 ± 2.2%. Mice expressing exon v3 (CD44v3-10) showed perfusion percentages of 25.9 ± 1.1%, compared to mice lacking this exon (CD44v4-10):19.1 ± 0.7%. Combined expression of CD44v3 and CD44s further improved perfusion restoration: 33.1 ± 2.6%.

CONCLUSION

Total CD44 and CD44v3 mRNA are upregulated during arteriogenesis. The absence of the variably spliced exon region impairs arteriogenesis. Presence of exon v3 of CD44 results in improved arteriogenesis. Expression of CD44s and CD44v3 provides a synergistic effect on arteriogenesis. As this combined expression still resulted in hampered arteriogenesis, a specific role of exon v2 in arteriogenesis appears likely.

目的

在小鼠后肢模型中，黏附分子 CD44 的缺失会减少侧支动脉生长（动脉生成）。CD44 的功能受 10 个可变剪接外显子（v1-v10）的表达影响，但其对动脉生成的影响尚不清楚。由于变体外显子 CD44v3 结合硫酸乙酰肝素并有助于生长因子的保存，我们假设 CD44 的可变剪接外显子区域，特别是外显子 CD44v3，参与了动脉生成。

材料和方法

结扎 C57BL/6J 小鼠的右侧股动脉，对组织进行 CD44 异构体表达的组织学和 qPCR 分析。在缺乏可变剪接外显子区域的小鼠（CD44s 敲入小鼠）以及在表达特定异构体的敲入株系（CD44v3-10 和 CD44v4-10）以及表达 CD44v3-10 和 CD44s 的双敲入小鼠中进行微球体灌注测量。

结果

股动脉结扎后总 CD44 和 CD44v3 mRNA 的表达增加，同时 CD44 相关剪接因子 Tra2-beta1 和 SRm160 的 mRNA 水平也增加。CD44v3 的表达仅限于生长侧支动脉的血管壁。缺乏可变剪接外显子区域的小鼠（CD44s）的灌注恢复明显减少：20.1 ± 1.3%，与背景株系相比：57.3 ± 2.2%。表达外显子 v3 的小鼠（CD44v3-10）的灌注百分比为 25.9 ± 1.1%，而缺乏该外显子的小鼠（CD44v4-10）为 19.1 ± 0.7%。CD44v3 和 CD44s 的共同表达进一步改善了灌注恢复：33.1 ± 2.6%。