Autophagy protein LC3 regulates the fibrosis of hypertrophic scar by controlling Bcl-xL in dermal fibroblasts
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Jihong Shi1,*, Shan Shi1,*, Bin Wu2,*, Jian Zhang1, Yan Li1, Xue Wu1, Julei Zhang1, Kejia Wang1, Bin Zhao1, Weixia Cai1, Xiaozhi Bai1, Dahai Hu1 and Hao Guan1
1Department of Burns and Cutaneous Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi 710032, China
2Department of Burns and Plastic Surgery, Affiated Hospital of Yan’an University, Yan’an, Shaanxi 716000, China
*These authors contributed equally to this work
Hao Guan, email: email@example.com
Dahai Hu, email: firstname.lastname@example.org
Keywords: microtubule-associated protein 1 light chain 3 (LC3), hypertrophic scar, fibroblast, fibrosis, Bcl-xL
Received: April 20, 2017 Accepted: July 29, 2017 Published: September 08, 2017
Hypertrophic scar (HS) is a serious skin fibrotic disease characterized by excessive hypercellularity and extracellular matrix (ECM) component deposition. Autophagy is a tightly regulated physiological process essential for cellular maintenance, differentiation, development and homeostasis. However, during the formation of HS, whether and how autophagy is regulated in dermal fibroblasts are still far from elucidated. Here we detected the autophagic capacity in HS and normal skin (NS) counterparts, explored and verified the key regulatory molecules of autophagy in HS-derived fibroblasts (HSFs), and validated the data using rabbit ear scar model. Transmission electron microscopy (TEM) and immunostaining data showed that LC3-positive cells and autophagosomes in HS/HSFs were more intensive relative to those in NS/NSFs groups. Knockdown of LC3 (shLC3) could significantly block the expressionof type I collagen (Col 1, p < 0.01) and type III collagen (Col 3, p < 0.01) and thus inhibit the fibrosis of HSFs. shLC3 resistant to autophagy was shown to be Bcl-xL-, not Bcl-2-dependent, and silencing of Bcl-xL (sibcl-xL) significantly increased apoptosis of HSFs (p < 0.01). Immunofluorescence results showed that instead of inhibiting α-SMA protein expression, shLC3 could change its architecture arrangement in HSFs. sibcl-xL showed that Bcl-xL was a key signaling molecule involved in HSFs autophagy. More importantly, both shLC3 and sibcl-xL obviously improved the appearance and architecture of the rabbit ear scar, and reduced scar formation on the rabbit ear. Therefore, the aberration of LC3 protein processing compromised autophagy in HS might associate with its pathogenesis in wound repair. LC3 regulated HS fibrosis by controlling the expression of Bcl-xL in HSFs. Thus, Bcl-xL might serve as a potential molecular target, providing a novel strategy for HS therapy.
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