Role and mechanism of Rasal2 in proliferation and migration of pulmonary artery smooth muscle cells
Received:January 12, 2022  
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DOI:10.11915/j.issn.1671-5403.2022.09.148
Key words:Ras protein activator like 2  pulmonary artery smooth muscle cells  proliferation  migration This work was supported by the Project of General Hospital of Western Theater Command
Author NameAffiliationE-mail
WANG Fang Department of Burns and Plastic Surgery, Chengdu 610083, China chenjie181213@sina.comrole 
HE Si-Yi Department of Cardiac and Vascular Surgery, General Hospital of Western Theater Command, Chengdu 610083, China chenjie181213@sina.comrole 
CHEN Jie Department of Cardiac and Vascular Surgery, General Hospital of Western Theater Command, Chengdu 610083, China chenjie181213@sina.comrole 
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Abstract:
      Objective To explore the role and mechanism of Ras protein activator like 2 (Rasal2) in the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs). Methods The expression of Rasal2 in pulmonary arteries of chronic hypoxia-induced pulmonary hypertension (CH-PH) mice and in hypoxia-challenged PASMCs was analyzed by Western blotting. After Rasal2 in PASMCs was silenced by transfection of siRNA, the phosphorylation levels of downstream effector molecules of mammalian target of rapamycin complex 1 (mTORC1), S6 and 4E-binding protein 1 (4EBP1) were determined by Western blotting, and the proliferation and migration of PASMCs were measured with Ki-67 immunofluorescence staining and Transwell assay, respectively. The proliferation and migration of PASMCs were further determined after restoration of mTORC1 activity by insulin. Results Compared with the Normoxic group, the mRNA [(2.57±0.15) vs (1.02±0.09); P<0.001) and protein [(2.18±0.36) vs (0.97±0.14); P<0.001) levels of Rasal2 were significantly increased in the pulmonary artery of the CH-PH group. In the PASMCs of the Hypoxic group, the mRNA [(2.41±0.20), (2.86±0.24) vs (1.03±0.12); both P<0.001] and protein [(2.50±0.32), (2.79±0.38) vs (1.13±0.12); both P<0.01] levels of Rasal2 were obviously higher after 12 h and 24 h of exposure when compared with the Normoxic group. Compared with the siCon group, the protein level of Rasal2 in PASMCs of the siRasal2 group was significantly deceased [(1.09±0.09) vs (0.33±0.04), P<0.001]. Compared with the Normoxic+siCon group, the percentage of Ki-67-positive cells [(62.75±7.54)% vs (13.90±2.35)%; P<0.001], percentage of migrated cells [(305.25±58.28)% vs (88.90±13.67)%; P<0.05], and expression of p-S6Ser235/236/S6 [(3.27±0.24) vs (1.06±0.14); P<0.001] and p-4EBP1Thr37/46/4EBP1 [(2.95±0.15) vs (1.07±0.06); P<0.001] were both increased in the Hypoxic+siCon group. Compared with the Hypoxic+siCon group, the percentage of Ki-67-positive cells [(19.25±5.34)% vs (62.75±7.54)%; P<0.001], percentage of migrated cells [(115.25±19.00)% vs (305.25±58.28)%; P<0.05], and expression of p-S6Ser235/236/S6 [(1.90±0.06) vs (3.27±0.24); P<0.001] and p-4EBP1Thr37/46/4EBP1 [(1.70±0.13) vs (2.95±0.15); P<0.001] in the Hypoxic+siRasal2 group were both reduced. Additionally, the percentage of Ki-67-positive cells [(61.25±3.10)% vs (27.00±3.46)%; P<0.001], percentage of migrated cells [(315.00±21.49)% vs (141.00±15.30)%; P<0.001], and expression of p-S6Ser235/236/S6 [(0.94±0.16) vs (0.36±0.11); P<0.01] and p-4EBP1Thr37/46/4EBP1 [(0.99±0.09) vs (0.61±0.03); P<0.01] were both elevated in the Hypoxic+siRasal2+Insulin group than the Hypoxic+siRasal2 group. Conclusion Rasal2 promotes the proliferation and migration of PASMCs via mTORC1 pathway.
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