RESUMEN
Changes in the T cell surface redox environment regulate critical cell functions, such as cell migration, viral entry and cytokine production. Cell surface protein disulfide isomerase (PDI) contributes to the regulation of T cell surface redox status. Cell surface PDI can be released into the extracellular milieu or can be internalized by T cells. We have found that galectin-9, a soluble lectin expressed by T cells, endothelial cells and dendritic cells, binds to and retains PDI on the cell surface. While endogenous galectin-9 is not required for basal cell surface PDI expression, exogenous galectin-9 mediated retention of cell surface PDI shifted the disulfide/thiol equilibrium on the T cell surface. O-glycans on PDI are required for galectin-9 binding, and PDI recognition appears to be specific for galectin-9, as galectin-1 and galectin-3 do not bind PDI. Galectin-9 is widely expressed by immune and endothelial cells in inflamed tissues, suggesting that T cells would be exposed to abundant galectin-9, in cis and in trans, in infectious or autoimmune conditions.
Asunto(s)
Membrana Celular/metabolismo , Galectina 1/metabolismo , Galectinas/metabolismo , Proteína Disulfuro Isomerasas/metabolismo , Linfocitos T/metabolismo , Sitios de Unión , Línea Celular , Membrana Celular/química , Membrana Celular/efectos de los fármacos , Membrana Celular/inmunología , Clonación Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Galectina 1/genética , Galectina 3/genética , Galectina 3/metabolismo , Galectinas/antagonistas & inhibidores , Galectinas/genética , Galectinas/farmacología , Expresión Génica , Regulación de la Expresión Génica , Glicosilación , Humanos , Modelos Moleculares , Oxidación-Reducción , Polisacáridos/química , Polisacáridos/metabolismo , Unión Proteica , Proteína Disulfuro Isomerasas/química , Proteína Disulfuro Isomerasas/genética , Proteína Disulfuro Isomerasas/inmunología , Transporte de Proteínas , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Recombinantes de Fusión/farmacología , Transducción de Señal , Linfocitos T/química , Linfocitos T/efectos de los fármacos , Linfocitos T/inmunologíaRESUMEN
The tympanic membrane (TM) is critical for hearing and requires continuous clearing of cellular debris, but little is known about homeostatic mechanisms in the TM epidermis. Using single-cell RNA sequencing, lineage tracing, whole-organ explant, and live-cell imaging, we show that homeostatic TM epidermis is distinct from other epidermal sites and has discrete proliferative zones with a three-dimensional hierarchy of multiple keratinocyte populations. TM stem cells reside in a discrete location of the superior TM and generate long-lived clones and committed progenitors (CPs). CP clones exhibit lateral migration, and their proliferative capacity is supported by Pdgfra+ fibroblasts, generating migratory but non-proliferative progeny. Single-cell sequencing of the human TM revealed similar cell types and transcriptional programming. Thus, during homeostasis, TM keratinocytes transit through a proliferative CP state and exhibit directional lateral migration. This work forms a foundation for understanding TM disorders and modeling keratinocyte biology.