Diversity of Mechanisms Underlying Latent TGF-β Activation in Recessive Dystrophic Epidermolysis Bullosa

hTERT-Driven Immortalization of RDEB Fibroblast and Keratinocyte Cell Lines Followed by Cre-Mediated Transgene Elimination

“…Fibrotic pathways are also affected in RDEB. It was shown previously that RDEB keratinocytes negatively regulated expression of transforming growth factor beta (TGF-β) produced by RDEB fibroblasts [16]. Here, we found that the CD109 molecule has enhanced expression in RDEB immKEB1 and partly in KEB2 lines and hypothesized that it could negatively modulate the TGF-β signaling in keratinocytes.…”

“…Immortalization with the HPV E6 and E7 genes could lead to obtaining cells with properties close to the primary ones but differing in several aspects, including downregulation of plasma membrane-associated proteins [15]. However, this approach was applied to establish a tractable model of RDEB HPV E6/E7-transformed keratinocyte lines [16]. Here, we propose lentivirus-mediated hTERT/BMI-1 immortalization to obtain new immortalized patient-specific cell lines, which retain their cell type-specific properties.…”

Impaired Wound Healing, Fibrosis, and Cancer: The Paradigm of Recessive Dystrophic Epidermolysis Bullosa

“…While animal models recapitulated the phenotype in RDEB and identified increased transforming growth factor-beta (TGFβ) signaling [18,21], studies in primary human cells clearly demonstrated that absent expression of wild-type C7 in RDEB dermal fibroblasts or knockdown of C7 in normal dermal fibroblasts leads to increased TGFβ signaling and a disruption to ECM protein organization and composition that is tumorpromoting [15,17]. Since these early studies, fibrosis and tumor development in RDEB have been attributed to substantial disruption to TGFβ signaling [22][23][24][25][26], yet the root cause of aberrant TGFβ signaling remains incompletely characterized. Thus, although TGFβ has emerged as a major disease modifier in RDEB and has provided a unifying mechanism for a range of independent studies identifying diverse routes to TGFβ activation [22][23][24][25][26], data do not identify a single, unifying mechanism of activation and likely points to a combination of contributing factors [22].…”

“…Since these early studies, fibrosis and tumor development in RDEB have been attributed to substantial disruption to TGFβ signaling [22][23][24][25][26], yet the root cause of aberrant TGFβ signaling remains incompletely characterized. Thus, although TGFβ has emerged as a major disease modifier in RDEB and has provided a unifying mechanism for a range of independent studies identifying diverse routes to TGFβ activation [22][23][24][25][26], data do not identify a single, unifying mechanism of activation and likely points to a combination of contributing factors [22]. In the following table (Table 1), we summarize known molecular targets for RDEB therapeutics and their mechanisms of action.…”

“…In addition, inflammation in RDEB skin leads to oxidative imbalance and TGFβ activation, triggering ECM protein synthesis, such as tenascin, periostin and fibronectin 1 [71]. Recent work has shown that RDEB fibroblasts have a greater ability to activate latent TGFβ when added in culture, and this is significantly increased after co-culture with keratinocytes, suggesting a role for both cell types in TGFβ activation in RDEB [22]. Proteomic studies of RDEB fibroblasts and keratinocytes have identified vesicle traffic, autophagy, and lysosomal changes, which potentially contribute to disrupted proteostasis and increase in ER-stress, providing a non-canonical route for TGFβ activation [17,20].…”