Search

Hearing loss is one of the most common sensory disorders. TMEM43 is expressed in cochlear glia-like supporting cells (GLSs) and is known to be associated with late-onset auditory neuropathy spectrum disorder (ANSD) and progressive hearing loss. Here, we describe the derivation of an induced pluripotent stem cell (iPSC) line from a patient lymphoblastoid cell line (LCL) carrying a single heterozygous nonsense variant (p.Arg372Ter (c.1114C > T)) in TMEM43 that leads to a truncated protein lacking the 4th transmembrane domain. This cell line can serve as a tool for disease modelling and development of therapeutic approaches to restore inner ear function.

Summary: Mutations in the gene encoding the type II transmembrane protease 3 (TMPRSS3) cause human hearing loss, although the underlying mechanisms that result in TMPRSS3-related hearing loss are still unclear. We combined the use of stem cell-derived inner ear organoids with single-cell RNA sequencing to investigate the role of TMPRSS3. Defective Tmprss3 leads to hair cell apoptosis without altering the development of hair cells and the formation of the mechanotransduction apparatus. Prior to degeneration, Tmprss3-KO hair cells demonstrate reduced numbers of BK channels and lower expressions of genes encoding calcium ion-binding proteins, suggesting a disruption in intracellular homeostasis. A proteolytically active TMPRSS3 was detected on cell membranes in addition to ER of cells in inner ear organoids. Our in vitro model recapitulated salient features of genetically associated inner ear abnormalities and will serve as a powerful tool for studying inner ear disorders. : The role of TMPRSS3 in auditory hair cell (HC) remains unclear. Nelson and colleagues generated stem cell-derived inner ear organoids with Tmprss3 mutations, which demonstrate that (1) inner ear organoids exhibit comparative effects of the genetic abnormality to its in vivo counterparts, (2) Tmprss3 mutations lead to HC apoptosis and reduced BK channels, and (3) TMPRSS3 localizes to the cell membrane. Keywords: deafness, degeneration, disease modeling, embryonic stem cell, hair cell, inner ear, organoid, TMPRSS3, vestibular system

Summary: The mammalian hair follicle arises during embryonic development from coordinated interactions between the epidermis and dermis. It is currently unclear how to recapitulate hair follicle induction in pluripotent stem cell cultures for use in basic research studies or in vitro drug testing. To date, generation of hair follicles in vitro has only been possible using primary cells isolated from embryonic skin, cultured alone or in a co-culture with stem cell-derived cells, combined with in vivo transplantation. Here, we describe the derivation of skin organoids, constituting epidermal and dermal layers, from a homogeneous population of mouse pluripotent stem cells in a 3D culture. We show that skin organoids spontaneously produce de novo hair follicles in a process that mimics normal embryonic hair folliculogenesis. This in vitro model of skin development will be useful for studying mechanisms of hair follicle induction, evaluating hair growth or inhibitory drugs, and modeling skin diseases. : Lee at el. describe a defined in vitro 3D culture system that generates skin organoids from mouse pluripotent stem cells. The skin organoids contain self-organized skin layers and skin appendages, including hair follicles, sebaceous glands, and adipocytes. Keywords: pluripotent stem cells, organoids, skin, epidermis, dermis, hair follicle, skin appendages, 3D culture