Project description:The next-generation-sequencing (NGS) of ribosome footprintings and poly(A) enriched RNA-seq have been proformed to examine transcriptional and translational changes in an mouse insulinoma cell MIN6 under acute and chronic endoplasmic reticular stresses.
Project description:Phenotypic plasticity and local adaptation via genetic change are two major mechanisms of response to dynamic environmental conditions. These mechanisms are not mutually exclusive, since genetic change can establish similar phenotypes to plasticity. This connection between both mechanisms raises the question of how much of the variation observed between species or populations is plastic and how much of it is genetic. In this study, we used a structured population of fire salamanders (Salamandra salamandra), in which two subpopulations differ in terms of physiology, genetics, mate-, and habitat preferences. Our goal was to identify candidate genes for differential habitat adaptation in this system, and to explore the degree of plasticity compared to local adaptation. We therefore performed a reciprocal transfer experiment of stream- and pond-originated salamander larvae and analyzed changes in morphology and transcriptomic profile (using species-specific microarrays). We observed that stream- and pond-originated individuals diverge in morphology and gene expression. For instance, pond-originated larvae have larger gills, likely to cope with oxygen-poor ponds. When transferred to streams, pond-originated larvae showed a high degree of plasticity, resembling the morphology and gene expression of stream-originated larvae (reversion); however the same was not found for stream-originated larvae when transferred to ponds, where the expression of genes related to reduction-oxidation processes was increased, possibly to cope with environmental stress. The lack of symmetrical responses between transplanted animals highlights the fact that the adaptations are not fully plastic and that some level of local adaptation has already occurred in this population. This study illuminates the process by which phenotypic plasticity allows local adaptation to new environments and its potential role in the pathway of incipient speciation.
Project description:The large secretory glycoprotein, thyroglobulin, is the primary translation product of thyroid follicular cells. This difficult-to-fold protein is readily susceptible to structural alterations that render the misfolded thyroglobulin unable to be exported from the endoplasmic reticulum (ER) a known cause of congenital hypothyroidism, with severe, chronic thyrocyte ER stress. Nevertheless, patients with this disease commonly grow a goiter indicative of thyroid cell survival and adaptation. To model this, we have treated PCCl3 thyrocytes with continuous exposure to tunicamcyin (causing an ER stress that can be specifically attributed to thyroglobulin misfolding). In response, PCCl3 cells escape by downregulating expression of Mfsd2a (the tunicamycin transporter). By contrast, following CRISPR/Cas9-mediated deletion of Mfsd2a, PCCl3 cells cannot escape the continuous, chronic effects of high-dose tunicamycin (as demonstrated by persistent accumulation of unglycosylated thyroglobulin); nevertheless the thyrocytes live and grow. A comprehensive proteomic analysis of these cells adapted to chronic ER protein misfolding reveals many hundreds of up-regulated proteins, supporting stimulation of ER chaperones, oxidoreductases, and stress responses as well as lipid biosynthesis pathways. Further, we noted: a) increased phospho-AMP-kinase-B (suggesting upregulated AMPK activity) and decreased phospho-S6 and protein translation (suggesting decreased mTOR activity), consistent with conserved cell survival/adaptation pathways; and b) a suggestion of less differentiated thyrocyte phenotype with decreased PAX8, FOXE1, and TPO protein, as well as a significant decrease of thyroglobulin mRNA levels.
Project description:Breast tumors expressing lower levels of Estrogen Receptor (ER) represent a distinct subset of breast cancer characterized by the emergence of basal-like characteristics within tumors that are traditionally considered luminal-like. Lineage tracing of these low-ER tumors in the MMTV-PyMT mouse mammary tumor model revealed that the basal-like tumor cells within these tumors arose from normal luminal epithelial cells, suggesting that luminal-to-basal plasticity is responsible for the evolution and emergence of basal-like characteristics within these tumors. This study aims to identify the potential drivers of this plasticity by using single-cell RNA sequencing to identify populations of lineage-restricted luminal cells and luminal-derived basal cells within the tumor, and comparing their gene expression profiles.
Project description:Adaptive evolution in response to cellular stress is a critical process implicated in a wide range of core biological and clinical phenomena. Two major routes of adaptation have been identified: non-genetic cellular plasticity, which allows expression of different phenotypes in novel environments, and genetic variation achieved by selection of fitter phenotypes. While these processes are now broadly accepted, their temporal and epistatic features in the context of cellular evolution and emerging drug resistance are contentious. In this manuscript, we generated hypomorphic alleles of the essential nuclear pore complex (NPC) gene NUP58. By dissecting both early and long-term mechanisms of adaptation in independent clones, we observed that early physiological adaptation correlated with transcriptome rewiring and upregulation of genes known to interact with the NPC. In contrast, long-term adaptation and fitness recovery occurred via focal amplification of NUP58 and restoration of mutant protein expression. These data support the concept that plasticity-mediated and genetic routes can co-exist to enable cellular evolution, with early flexibility of phenotype allowing later acquisition of genetic adaptations to a specific impairment. We propose this approach as a genetic model to mimic targeted drug therapy in human cells and dissection of early and late adaptation. Targeting both mechanisms in parallel may reduce the emergence of drug resistance
Project description:Microbial communities respond to temperature with physiological adaptation and compositional turnover. Whether thermal selection of enzymes explains marine microbiome plasticity in response to temperature remains unresolved. By quantifying the thermal behaviour of seven functionally-independent enzyme classes (esterase, extradiol dioxygenase, phosphatase, beta-galactosidase, nuclease, transaminase, and aldo-keto reductase) in native proteomes of marine sediment microbiomes from the Irish Sea to the southern Red Sea, we record a significant effect of the mean annual temperature (MAT) on enzyme’s response (R2, 0.51–0.80, p < 0.01 in all cases). Activity and stability profiles of 228 esterases and 5 extradiol dioxygenases from sediment and seawater across 70 locations worldwide (latitude 62.2°S–16°N, MAT –1.4ºC–29.5ºC) validate this thermal pattern. Modelling the esterase phase transition temperature as a measure of structural flexibility, confirm the observed relationship with MAT. Furthermore, when considering temperature variability in sites with non-significantly different MATs, the broadest range of enzyme thermal behaviour and the highest growth plasticity of the enriched heterotrophic bacteria occur in samples with the widest annual thermal variability. These results indicate that temperature-driven enzyme selection shapes microbiome thermal plasticity and that thermal variability finely tunes such processes and should be considered alongside MAT in forecasting microbial community thermal response
Project description:The development and maintenance of organismal form results from dynamic interactions between genome, protein interaction, physiology and the external environment. Bioelectric signaling represents an important epigenetic layer of control over processes of large-scale patterning during development and regeneration. However it is still largely unknown how physiological plasticity and adaptation operate during regenerative processes. Planarian flatworms are an exceptional system in which to study the interplay between genetics and environment, as they are able to regenerate any tissue or organ after traumatic injury. Here, we study acquired tolerance to a bioelectric homeostasis-altering pharmacological treatment. After exposure to the non-selective potassium channel blocker BaCl2, D. japonica flatworms display extreme depolarization of the head and then violently degenerate their anterior tissues via an apoptotic mechanism. Remarkably, when kept in fresh barium solution, they then regenerate a head that displays normal bioelectric state and is non-responsive to the channel blocker. Transcriptomics using RNAseq was used to characterize transcriptional changes that occur during this adaptation process, identifying a number of ion translocators that are differentially expressed with BaCl2, including the BK channel which is resistant to barium blockade. Many of these channels were identified as cation transporters (cation-transporting ATPases, small conductance calcium activated potassium (SK) channels, and sodium/hydrogen exchangers), suggesting that the physiological buffering of a depolarizing treatment is dependent on employing alternative means of transporting cations into and out of anterior cells and tissues. Moreover, pathway enrichment analysis revealed that transcriptional networks related to synaptic plasticity, nervous system development, neurotransmission, and nerve development were increased ~2 to 3-fold. Transcriptome responses were also activated for membrane steady potential, excitatory junction potential, and membrane hyperpolarization, all associated with the modulation of Vmem. The ability to adjust to physiological conditions that are strongly injurious to normal anatomy, by altering the transcriptome is a powerful adaptive capability of physiological circuits. Further studies on this plasticity will shed light on numerous regenerative and patterning mechanisms in the context of evolution, and will contribute to biomedical therapies that exploit this innate robustness.