Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
Alessia Secone Seconetti
Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
Giorgio De Santis
Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
Giovanni Pellacani
Department of Surgery, Medicine, Dentistry, and Morphological Sciences, University of Modena and Reggio Emilia, Modena, Italy
Tobias Hirsch
Department of Plastic Surgery, Burn Centre, BG University Hospital Bergmannsheil, Ruhr-University Bochum, Germany
Tobias Rothoeft
Department of Neonatology and Pediatric Intensive Care, University Children’s Hospital, Ruhr-University Bochum, Germany
Norbert Teig
Department of Neonatology and Pediatric Intensive Care, University Children’s Hospital, Ruhr-University Bochum, Germany
Graziella Pellegrini
Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy; Department of Surgery, Medicine, Dentistry, and Morphological Sciences, University of Modena and Reggio Emilia, Modena, Italy
Johann W. Bauer
EB House Austria and Department of Dermatology, University Hospital of the Paracelsus Medical University, Salzburg, Austria
Michele De Luca
Centre for Regenerative Medicine “Stefano Ferrari,” Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy; Corresponding author
Summary: Laminin 332-deficient junctional epidermolysis bullosa (JEB) is a severe genetic skin disease. JEB is marked by epidermal stem cell depletion, the origin of which is unknown. We show that dysregulation of the YAP and TAZ pathway underpins such stem cell depletion. Laminin 332-mediated YAP activity sustains human epidermal stem cells, detected as holoclones. Ablation of YAP selectively depletes holoclones, while enforced YAP blocks conversion of stem cells into progenitors and indefinitely extends the keratinocyte lifespan. YAP is dramatically decreased in JEB keratinocytes, which contain only phosphorylated, inactive YAP. In normal keratinocytes, laminin 332 and α6β4 ablation abolish YAP activity and recapitulate the JEB phenotype. In JEB keratinocytes, laminin 332-gene therapy rescues YAP activity and epidermal stem cells in vitro and in vivo. In JEB cells, enforced YAP recapitulates laminin 332-gene therapy, thus uncoupling adhesion from proliferation in epidermal stem cells. This work has important clinical implication for ex vivo gene therapy of JEB. : Gene therapy of junctional epidermolysis bullosa is hampered by the epidermal stem cell loss marking this disease. De Rosa et al. find that YAP dysregulation underpins such loss, which is recapitulated by laminin 332 and α6β4 integrin ablation. Combined cell and gene therapy rescues adhesion, YAP function, and stem cells. Keywords: epidermal stem cells, epidermolysis bullosa, YAP, cell and gene therapy
