α‐2‐Macroglobulin induces the shedding of microvesicles from cutaneous wound myofibroblasts

Abstract

Microvesicles (MVs) are recognized as an important class of cell‐to‐cell messengers. Although the properties of MVs are increasingly documented, the mechanisms regulating MV biogenesis remain debated. Myofibroblasts are a key cellular component of wound healing and have been shown to produce MVs upon stimulation with serum. However, the mediator(s) responsible for the observed effect of serum on MV release have yet to be identified. To isolate the molecule(s) of interest, serum proteins were sequentially separated using chromatography, selective precipitation, and electrophoresis. MV production was assessed throughout the purification and after stimulation of myofibroblasts with two potent purified molecules. α‐2‐Macroglobulin (A2M) was thereby found to dose‐dependently stimulate MV release. We confirmed the presence of the A2M receptor, low‐density lipoprotein receptor‐related protein‐1 (LRP1), on myofibroblasts. Inhibition of LRP1 resulted in a significant decrease in MV production. Together, our results suggest that A2M positively regulates MV shedding through the activation of LRP1 on myofibroblasts.

Shedding of proangiogenic microvesicles from hypertrophic scar myofibroblasts

“…[25,26] Our results suggest, however, shedding from Wmyos in our recent work on intercellular communication in normal skin repair. [7] In the present study, we demonstrated that A2M, at concentrations within the physiological range, enhances MV production by Hmyos in a dose-dependent manner. Although a certain amount of A2M accumulates in dermal tissue following any cutaneous injury, hypertrophic scars and lesions of thermal origin are characterized by excessive inflammation and increased extravasation of serum proteins, including A2M, into the wound bed.…”

“…MV production was quantified by autofluorescence emission spectra analysis as previously described. [ 7 ] Briefly, after 24 hours of treatment, MVs were isolated from cell culture supernatants by centrifugation at 21 000 × g for 20 minutes at 4°C. Concurrently, the cells were trypsinized and pelleted by centrifugation at 300 × g for 5 minutes at 4°C.…”

“…MV production was quantified by autofluorescence emission spectra analysis as previously described. [7] Briefly, after 24…”

“…[4][5][6] A previous report from our team revealed that MV shedding from acute wound myofibroblasts is positively regulated by the serum protein α-2-macroglobulin (A2M). [7] Upon wound closure, myofibroblasts usually undergo apoptosis. Under pathological circumstances, however, apoptosis-resistant myofibroblasts persist in the closed wound, thereby leading to fibrous tissue overgrowth and hypertrophic scar formation.…”

Comprehensive landscape of extracellular vesicle-derived RNAs in cancer initiation, progression, metastasis and cancer immunology

“…Additional cell surface receptors are involved in microvesicle secretion, including G protein-coupled receptor 30 [81], α-2-Macroglobulin receptor [82], transient receptor potential vanilloid type 1 [88] and tissue factor [83]. In addition, microvesicle secretioin is also induced by intratumoral hypoxia, which transcriptionally regulates the expression of the small GTPase Rab22A that colocalizes with budding MVs [84].…”