TGFβ Triggers miR-143/145 Transfer from Smooth Muscle Cells to Endothelial Cells, Thereby Modulating Vessel Stabilization
Rationale: The miR-143/145 cluster is highly expressed in smooth muscle cells (SMCs), where it regulates phenotypic switch and vascular homeostasis. Whether it plays a role in neighboring endothelial cells (ECs) is still unknown.
Objective: To determine whether SMCs control EC functions through passage of miR-143 and miR-145.
Methods and Results: We used co-cultures of SMCs and ECs under different conditions as well as intact vessels to assess the transfer of miR-143 and miR-145 from one cell type to another. Imaging of co-cultured cells transduced with fluorescent miRNAs suggested that miRNA transfer involves membrane protrusions known as tunneling nanotubes. Furthermore, we showed that miRNA passage is modulated by the transforming growth factor beta (TGFβ pathway, since both a specific TGFβ inhibitor (SB431542) and an shRNA against TGFβ RII suppressed the passage of miR-143/145 from SMCs to ECs. Moreover, miR-143 and miR-145 modulated angiogenesis by reducing the proliferation index of ECs and their capacity to form vessel-like structures when cultured on matrigel. We also identified hexokinase II (HKII) and integrin beta 8 (ITGβ8)—two genes essential for the angiogenic potential of ECs—as targets of miR-143 and miR-145, respectively. The inhibition of these genes modulated EC phenotype, similarly to miR-143 and miR-145 overexpression in ECs. These findings were confirmed by ex vivo and in vivo approaches, in which it was shown that TGFβ and vessel stress, respectively, triggered miR-143/145 transfer from SMCs to ECs.
Conclusions: Our results demonstrate that miR-143 and miR-145 act as communication molecules between SMCs and ECs to modulate the angiogenic and vessel stabilization properties of ECs.
- Received December 9, 2014.
- Revision received March 20, 2015.
- Accepted March 23, 2015.