Involvement of impaired desmosome-related proteins in hypertrophic scar intraepidermal blister formation

Desmoplakin mutations in cardiac fibroblasts cause TGFβ1-mediated pathological fibrogenesis in desmoplakin cardiomyopathy via beclin-1 regulation

Background

Pathological fibrosis is a major finding in cardiovascular diseases and can result in arrhythmia and heart failure. Desmosome gene mutations can lead to arrhythmogenic cardiomyopathy (ACM). Among ACM, pathogenic desmoplakin ( DSP ) variants cause a distinctive cardiomyopathy with excessive cardiac fibrosis that could precede ventricular dysfunction. DSP variants are also linked to other fibrotic diseases. Whether DSP plays any role in pathological fibrosis remain unknown.

Methods

Mesenchymal stromal cells (MSCs) are resident fibroblast-like cells that are responsible for fibrogenesis in most organs, including hearts. We first used unbiased genome-wide analyses to generate cardiac fibroblasts-like, induced pluripotent stem cell-derived MSCs from normal donors and ACM patients with DSP mutations. We then studied the fibrogenic responses of cardiac MSCs to transforming growth factor beta-1 (TGF-β1) using Western/Co-IP, autophagy assay, gene knockdowns/over-expressions, genomic analyses, mouse DSP knockdown models, immunostaining, and qPCR.

Results

TGFβ1 induced excessive accumulations of vimentin (VIM)/fibrillar collagens, and over-activated fibrotic genes in DSP- mutant MSCs when compared to normal MSCs. In normal MSCs, VIMs bind to wild-type DSP during normal fibrogenesis after TGFβ1. DSP- mutant MSCs exhibited a haplo-insufficient phenotype with increased DSP-unbound VIMs that sequestered beclin-1 (BECN1) from activating autophagy and caveolin-1 (CAV1)-mediated endocytosis. Decreased autophagy caused collagen accumulations and diminished CAV1 endocytosis resulted in abnormal CAV1 plaque formation that over-activated fibrotic genes [ COL1A1, COL3A1, and fibronectin ( FN )] via heightened p38 activities after TGFβ1. Genome-wide analysis and DSP knockdown in mouse fibroblasts confirmed this novel role of DSP mutations in pathological fibrosis. Overexpression of VIM-binding domains of DSP could suppress pathological fibrosis by increasing collagen autophagic degradation and decreasing fibrotic gene expressions.

Conclusions

Our data reveal that DSP deficiency in MSCs/fibroblasts leads to exaggerated fibrogenesis in DSP-cardiomyopathy by decreasing BECN1 availability for autophagy and CAV1-endocytosis. Overexpression of VIM binding domains of DSP could be a new strategy to treat pathological fibrosis.

Integrative Analysis of Lactylome and Proteome of Hypertrophic Scar To Identify Pathways or Proteins Associated with Disease Development

Lactylation (Kla), a recently discovered post-translational modification derived from lactate, plays crucial roles in various cellular processes. However, the specific influence of lactylation on the biological processes underlying hypertrophic scar formation remains unclear. In this study, we present a comprehensive profiling of the lactylome and proteome in both hypertrophic scars and adjacent normal skin tissues. A total of 1023 Kla sites originating from 338 nonhistone proteins were identified based on lactylome analysis. Proteome analysis in hypertrophic scar and adjacent skin samples revealed the identification of 2008 proteins. It is worth noting that Kla exhibits a preference for genes associated with ribosome function as well as glycolysis/gluconeogenesis in both normal skin and hypertrophic scar tissues. Furthermore, the functional enrichment analysis demonstrated that differentially lactyled proteins are primarily involved in proteoglycans, HIF-1, and AMPK signaling pathways. The combined analysis of the lactylome and proteome data highlighted a significant upregulation of 14 lactylation sites in hypertrophic scar tissues. Overall, our investigation unveiled the significant involvement of protein lactylation in the regulation of ribosome function as well as glycolysis/gluconeogenesis, potentially contributing to the formation of hypertrophic scars.

Role and function of plakophilin 3 in cancer progression and skin disease

Plakophilin 3 (PKP3), a component of desmosome, is aberrantly expressed in many kinds of human diseases, especially in cancers. Through direct interaction, PKP3 binds with a series of desmosomal proteins, such as desmoglein, desmocollin, plakoglobin, and desmoplakin, to initiate desmosome aggregation, then promotes its stability. As PKP3 is mostly expressed in the skin, loss of PKP3 promotes the development of several skin diseases, such as paraneoplastic pemphigus, pemphigus vulgaris, and hypertrophic scar. Moreover, accumulated clinical data indicate that PKP3 dysregulates in diverse cancers, including breast, ovarian, colon, and lung cancers. Numerous lines of evidence have shown that PKP3 plays important roles in multiple cellular processes during cancer progression, including metastasis, invasion, tumor formation, autophagy, and proliferation. This review examines the diverse functions of PKP3 in regulating tumor formation and development in various types of cancers and summarizes its detailed mechanisms in the occurrence of skin diseases.

The Mechanism of miR-222 Targets Matrix Metalloproteinase 1 in Regulating Fibroblast Proliferation in Hypertrophic Scars

This study aimed to investigate the value of miR-222 in hypertrophic scars (HS). Specific mechanisms were used to measure the level of miR-222, while MTT assay, flow cytometry, western blot and qRT-PCR were employed to detect the relative proteins after fibroblasts were transfected with the miR-222 mimic/inhibitor. The direct target of miR-222 was determined by Dual-Luciferase Reporter assay. Furthermore, qRT-PCR and western blot were employed to detect the matrix metalloproteinase 1 (MMP1) RNA/protein after fibroblasts were transfected with the miR-222 mimic/inhibitor. These results revealed that miR-222 was significantly upregulated in HS fibroblasts. The overexpression of miR-222 enhanced the HS fibroblast proliferation, increased the cell population in the S phase, inhibited the cell apoptosis, enhanced the expression levels of Col1A1, Col3A1 mRNA/protein, proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin E1 and CDK1 and reduced the expression levels of cleaved caspase-3/9. However, the miR-222 suppression triggered opposite effects. Furthermore, miR-222 played a regulatory role in HS by negatively regulating its target gene MMP1 by binding with its 3'-untranslated region. The overexpression of MMP1 reduced the expression levels of PCNA and cyclin D1, but enhanced the expression levels of cleaved caspase-3. Therefore, MiR-222 and MMP1 have potential value for HS. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .