Discovery of increased epidermal DNAH10 expression after regeneration of dermis in a randomized with-in person trial - reflections on psoriatic inflammation

Olfactomedin 4 regulates migration and proliferation of immortalized non-transformed keratinocytes through modulation of the cell cycle machinery and actin cytoskeleton remodelling

Olfactomedin 4 (OLFM4), a multifunctional matricellular protein, is involved in regulation of angiogenesis, innate immunity, inflammation, tumorigenesis and metastasis formation via modulation of important cellular processes like adhesion, proliferation, differentiation as well as apoptosis. In our previous work we demonstrated the upregulation of OLFM4 during liver regeneration and cutaneous wound healing. Here we studied the outcomes of OLFM4 downregulation in human immortalized keratinocytes - the HaCaT cells. The suppression of OLFM4 inhibited migration but enhanced the proliferation of these cells. By using proteomic, and phosphoproteomic analysis, we found that OLFM4 downregulation induced changes in the levels of 184 proteins and 348 phosphosites. An integrated pathway analysis suggested that the increased phosphorylation of CDK7 at Ser164 and Thr170 may serve as the key event in the activation of CDK2 and consequent activation of cell cycle progression. Furthermore, the decrease in GIT1 and WAVE2 protein levels were connected to the disorganization of the actin cytoskeleton, reduction of lamellipodia formation at the leading edge of HaCaT cells, and decrease in their migration capacity.

Thrombospondin-4 Is a Soluble Dermal Inflammatory Signal That Selectively Promotes Fibroblast Migration and Keratinocyte Proliferation for Skin Regeneration and Wound Healing

Thrombospondin-4 (THBS4) is a non-structural extracellular matrix molecule associated with tissue regeneration and a variety of pathological processes characterized by increased cell proliferation and migration. However, the mechanisms of how THBS4 regulates cell behavior as well as the pathways contributing to its effects have remained largely unexplored. In the present study we investigated the role of THBS4 in skin regeneration both in vitro and in vivo. We found that THBS4 expression was upregulated in the dermal compartment of healing skin wounds in humans as well as in mice. Application of recombinant THBS4 protein promoted cutaneous wound healing in mice and selectively stimulated migration of primary fibroblasts as well as proliferation of keratinocytes in vitro. By using a combined proteotranscriptomic pathway analysis approach we discovered that β-catenin acted as a hub for THBS4-dependent cell signaling and likely plays a key role in promoting its downstream effects. Our results suggest that THBS4 is an important contributor to wound healing and its incorporation into novel wound healing therapies may be a promising strategy for treatment of cutaneous wounds.

Atypical acute myeloid leukemia-specific transcripts generate shared and immunogenic MHC class-I-associated epitopes

Acute myeloid leukemia (AML) has not benefited from innovative immunotherapies, mainly because of the lack of actionable immune targets. Using an original proteogenomic approach, we analyzed the major histocompatibility complex class I (MHC class I)-associated immunopeptidome of 19 primary AML samples and identified 58 tumor-specific antigens (TSAs). These TSAs bore no mutations and derived mainly (86%) from supposedly non-coding genomic regions. Two AML-specific aberrations were instrumental in the biogenesis of TSAs, intron retention, and epigenetic changes. Indeed, 48% of TSAs resulted from intron retention and translation, and their RNA expression correlated with mutations of epigenetic modifiers (e.g., DNMT3A). AML TSA-coding transcripts were highly shared among patients and were expressed in both blasts and leukemic stem cells. In AML patients, the predicted number of TSAs correlated with spontaneous expansion of cognate T cell receptor clonotypes, accumulation of activated cytotoxic T cells, immunoediting, and improved survival. These TSAs represent attractive targets for AML immunotherapy.