Project description:The transition zones (TZs) of the squamous and columnar epithelium constitute hotspots for the emergence of cancers, often preceded by metaplasia, where one epithelial type is replaced by cells of another type. Yet, it remains uncertain how the spatial organization of the epithelia is maintained and how the TZ niche is remodeled during metaplasia. Here, we used single-cell RNA-sequencing to characterize subpopulations of the epithelium as well as the underlying stromal compartment of endo and ectocervix, encompassing the TZ. Mouse lineage tracing, organoid culture and smRNA-ISH revealed that the two epithelia derive from two separate cervix-resident lineage-specific stem cell populations that are regulated by opposing WNT signals from the stroma. Using a mouse model of cervical metaplasia, we further show that the endocervical stroma undergoes remodeling and increased expression of WNT signaling inhibitor Dickkopf-2 (DKK2), promoting the outgrowth of ectocervical stem cells. Thus, homeostasis at the TZ results from divergent stromal signals, driving the differential proliferation of resident epithelial lineages.
Project description:The transition zones of the squamous and columnar epithelia constitute hotspots for the emergence of cancer, often preceded by metaplasia, in which one epithelial type is replaced by another. It remains unclear how the epithelial spatial organization is maintained and how the transition zone niche is remodelled during metaplasia. Here we used single-cell RNA sequencing to characterize epithelial subpopulations and the underlying stromal compartment of endo- and ectocervix, encompassing the transition zone. Mouse lineage tracing, organoid culture and single-molecule RNA in situ hybridizations revealed that the two epithelia derive from separate cervix-resident lineage-specific stem cell populations regulated by opposing Wnt signals from the stroma. Using a mouse model of cervical metaplasia, we further show that the endocervical stroma undergoes remodelling and increases expression of the Wnt inhibitor Dickkopf-2 (DKK2), promoting the outgrowth of ectocervical stem cells. Our data indicate that homeostasis at the transition zone results from divergent stromal signals, driving the differential proliferation of resident epithelial lineages.
Project description:Photosynthetic induction, characterized by the lag in CO2 assimilation rates during transition from darkness to light, has traditionally been attributed to Rubisco activase activity and stomatal opening. Yet, the faster induction of photosynthesis in the 2-Cys peroxiredoxins (Prxs) mutant (2cpab) suggested a role for oxidative signals in regulating photosynthetic rates, although the underlying molecular mechanism remains unclear. SPEAR, a redox proteomics approach, was used to systematically map redox changes occurring during photosynthesis induction and to unravel the role of 2-Cys Prxs in shaping these redox alterations. No significant difference was observed in protein expression levels between WT and 2cpab plants, suggesting that protein abundance does not account for the 2cpab phenotype. During the transition from dark to low light, 82 and 54 cysteine-containing peptides were reduced or oxidized, respectively, in WT plants. Most redox-regulated cysteines in photosynthetic proteins were found oxidized in the dark and became reduced in response to light. A reverse pattern was observed among redox-regulated cysteines in proteins involved in starch degradation and chloroplast glycolysis, which shifted from a reduced to an oxidized state in response to light. These findings demonstrate the initiation of two opposing redox responses, affecting distinct sets of metabolic proteins during the induction phase. Remarkably, a significantly lower number of cysteines were reduced or oxidized in 2cpab plants, highlighting the crucial role 2-Cys Prxs play in shaping both signals. Taken together, rotational shifts between metabolic pathways during the photosynthesis induction phase are regulated by two opposing redox signals mediated by 2-Cys Prx activity.
Project description:Photosynthetic induction, characterized by the lag in CO2 assimilation rates during transition from darkness to light, has traditionally been attributed to Rubisco activase activity and stomatal opening. Yet, the faster induction of photosynthesis in the 2-Cys peroxiredoxins (Prxs) mutant (2cpab) suggested a role for oxidative signals in regulating photosynthetic rates, although the underlying molecular mechanism remains unclear. SPEAR, a redox proteomics approach, was used to systematically map redox changes occurring during photosynthesis induction and to unravel the role of 2-Cys Prxs in shaping these redox alterations. No significant difference was observed in protein expression levels between WT and 2cpab plants, suggesting that protein abundance does not account for the 2cpab phenotype. During the transition from dark to low light, 82 and 54 cysteine-containing peptides were reduced or oxidized, respectively, in WT plants. Most redox-regulated cysteines in photosynthetic proteins were found oxidized in the dark and became reduced in response to light. A reverse pattern was observed among redox-regulated cysteines in proteins involved in starch degradation and chloroplast glycolysis, which shifted from a reduced to an oxidized state in response to light. These findings demonstrate the initiation of two opposing redox responses, affecting distinct sets of metabolic proteins during the induction phase. Remarkably, a significantly lower number of cysteines were reduced or oxidized in 2cpab plants, highlighting the crucial role 2-Cys Prxs play in shaping both signals. Taken together, rotational shifts between metabolic pathways during the photosynthesis induction phase are regulated by two opposing redox signals mediated by 2-Cys Prx activity.
Project description:The cellular origin of cervical cancers remains unclear. Revealing molecular details of transformation in this tissue has been hampered by the lack of culture systems, resembling the in vivo cervical architecture. Here we established a long-term in vitro 3D cervical organoid model derived from stem cells of human or mouse cervical tissue which recapitulates the in vivo stratified ectocervical and columnar endocervical epithelium. Stratified and columnar cervical epithelia arise from two discrete unipotent stem cell populations of the endocervix. Unique stem cell signatures reveal a dependency on intrinsic Notch and Wnt microenvironmental signals. The genetic signatures of KRT5+ stratified vs KRT7+ columnar cervical cells establish discrete groups of cervical cancer of the squamous and adenocarcinoma types, respectively. Cervical tissue morphology is guided by the interplay of two discrete unipotent cervical stem cell populations and the spatio-temporal distribution of signals from the stroma.
Project description:The cellular origin of cervical cancers remains unclear. Revealing molecular details of transformation in this tissue has been hampered by the lack of culture systems, resembling the in vivo cervical architecture. Here we established a long-term in vitro 3D cervical organoid model derived from stem cells of human or mouse cervical tissue which recapitulates the in vivo stratified ectocervical and columnar endocervical epithelium. Stratified and columnar cervical epithelia arise from two discrete unipotent stem cell populations of the endocervix. Unique stem cell signatures reveal a dependency on intrinsic Notch and Wnt microenvironmental signals. The genetic signatures of KRT5+ stratified vs KRT7+ columnar cervical cells establish discrete groups of cervical cancer of the squamous and adenocarcinoma types, respectively. Cervical tissue morphology is guided by the interplay of two discrete unipotent cervical stem cell populations and the spatio-temporal distribution of signals from the stroma.
Project description:Most vertebrate species undergo tooth replacement throughout adult life. This process is marked by the shedding of existing teeth and the regeneration of tooth organs. However, little is known about the genetic circuitry regulating tooth replacement. Here, we tested whether fish orthologs of genes known to regulate mammalian hair regeneration have effects on tooth replacement. Using two fish species that demonstrate distinct modes of tooth regeneration, threespine stickleback (Gasterosteus aculeatus) and zebrafish (Danio rerio), we found that transgenic overexpression of four different genes changed tooth replacement rates in the direction predicted by a hair regeneration model: Wnt10a and Grem2a increased tooth replacement rate, whereas Bmp6 and Dkk2 strongly inhibited tooth formation. Thus, similar to known roles in hair regeneration, Wnt and BMP signals promote and inhibit regeneration, respectively. Regulation of total tooth number was separable from regulation of replacement rates. RNA sequencing of stickleback dental tissue showed that Bmp6 overexpression resulted in an upregulation of Wnt inhibitors. Together, these data support a model in which different epithelial organs, such as teeth and hair, share genetic circuitry driving organ regeneration.