Project description:Extracellular signaling and nutrient availability are major factors for cell fate decision. Responds to extracellular information requires metabolic alterations and differential gene expression. However, how cells integrate extracellular signals (e.g. hormones) and cellular metabolic status to coordinate transcriptional outcome is poorly understood. We hypothesized that fluctuations in nuclear nicotinamide adenine dinucleotide (NAD+) levels act as a signal to integrate cellular glucose metabolism and transcription program during adipocyte differentiation. To test this hypothesis, we performed RNA-seq on control, Nmnat1 and Parp1 knockdown 3T3-L1 cells during various time point of differentiation.
Project description:The development of a complex organ requires the proper differentiation and production of appropriate numbers of each of its constituent cell types, as well as their correct positioning within the organ. During Drosophila cardiogenesis, all three of these processes are controlled by jumeau (jumu) and Checkpoint suppressor homologue (CHES-1-like), two genes encoding forkhead transcription factors that were discovered utilizing an integrated genetic, genomic and computational strategy which identified 70 novel genes expressed in the developing Drosophila heart. Both jumu and CHES-1-like are required during asymmetric cell division for the derivation of two distinct cardiac cell types from their mutual precursor, and in symmetric cell division to produce yet a third type of heart cell. jumu and CHES-1-like control the division of cardiac progenitors by regulating the activity of Polo, a kinase involved in multiple steps of mitosis. This pathway demonstrates how transcription factors integrate diverse developmental processes during organogenesis. GFP-positive cells were profiled from Stage 11-12 Drosophila embryos of the following two genotypes: twi-GAL4 UAS-2EGFP/UAS-jumu and twi-GAL4 UAS-2EGFP
Project description:Satellite cells are adult muscle stem cells responsible for muscle regeneration after acute or chronic injuries. The balance between stem cell self-renewal and differentiation impacts the kinetics and efficiency of skeletal muscle regeneration. This study elucidated the function of Islr in satellite cell asymmetric division. Satellite cell specific deletion of Islr compromises muscle regeneration in adult mice by impairing the satellite cell pool. Islr is pivotal for satellite cell proliferation and its deletion promotes asymmetric cell fate segregation of satellite cells. A mechanistic search revealed that Islr interacts and stabilizes the Sparc protein, which activates p-ERK1/2 signaling required for asymmetric division. In combination, the findings have identified Islr as a key regulator of satellite cell asymmetric division through the Sparc/p-ERK1/2 signaling pathway, which provides a new insight into satellite cell biology and open avenues for the treatment of myopathy.
Project description:Metabolic characteristics of adult stem cells are distinct from their differentiated progeny, and cellular metabolism is emerging as a potential driver of cell fate conversions. However, how metabolism influences fate determination remains unclear. Here, we identified inherited metabolism imposed by functionally distinct mitochondrial age-classes as a fate determinant in asymmetric division of epithelial stem-like cells. While chronologically old mitochondria support oxidative respiration, new organelles are immature and metabolically less active. Upon cell division, selectively segregated mitochondrial age-classes elicit a metabolic bias in progeny cells, with old mitochondria imposing oxidative energy metabolism inducing differentiation. High pentose phosphate pathway flux, promoting redox maintenance, is favoured in cells receiving newly synthesised mitochondria, and is required to maintain stemness during early fate determination after division. Our results demonstrate that fate decisions are susceptible to intrinsic metabolic bias imposed by selectively inherited mitochondria.
Project description:Asymmetric cell division results in two distinctly fated daughter cells to generate cellular diversity. A major molecular hallmark of an asymmetric division is the unequal partitioning of cell-fate determinant proteins. We have previously established that growth factor signaling promotes protein depalmitoylation to foster polarized protein localization, which in turns drives migration and metastasis. Here, we report protein palmitoylation as a key mechanism for the asymmetric partitioning of the cell-fate determinants Numb (Notch antagonist) and β-catenin (canonical Wnt regulator) through the activity of a depalmitoylating enzyme, APT1. Using point mutants, we show specific palmitoylated residues on proteins, such as Numb, are required for asymmetric localization. Furthermore, by live-cell imaging, we show that reciprocal interactions between APT1 and CDC42 regulate the asymmetric localization of Numb and β-catenin to the plasma membrane. This in turn restricts Notch and Wnt transcriptional activity to one daughter cell. Moreover, we show altering APT1 expression changes the transcriptional signatures to those resembling that of Notch and β-catenin in MDA-MB-231 cells. We also show loss of APT1 depletes the population of CD44+/CD24lo/ALDH+ tumorigenic cells in colony formation assays. Together, the findings of this study demonstrate that palmitoylation, via APT1, is a major mechanism of asymmetric cell division regulating Notch and Wnt-associated protein dynamics, gene expression, and cellular functions.
Project description:Asymmetric partitioning of fate-determinants is a mechanism that contributes to T cell differentiation. However, it remained unclear whether the ability of T cells to divide asymmetrically is influenced by their differentiation state, as well as if enforcing asymmetric cell division rates would have an impact on T cell differentiation and memory formation. Using the murine LCMV infection model, we established a correlation between cell stemness and the ability of CD8+ T cells to undergo asymmetric cell division (ACD). Transient mTOR inhibition proved to increase ACD rates in naïve and memory cells, and to install this ability in exhausted CD8+ T cells. Functionally, enforced ACD correlated with increased memory potential, leading to more efficient recall response and viral control upon acute or chronic LCMV infection. Moreover, transient mTOR inhibition also increased ACD rates in human CD8+ T cells. Transcriptional profiling of first daughter cells, obtained by sorting CD8lo and CD8hi cells after in vitro stimulation, revealed that progenies emerging from enforced ACD exhibited more pronounced early memory signatures, which functionally endowed these cells with strengthened memory features.
Project description:The development of a complex organ requires the specification of appropriate numbers of each of its constituent cell types, as well as their proper differentiation and correct positioning relative to each other. During Drosophila cardiogenesis, all three of these processes are controlled by jumeau (jumu) and Checkpoint suppressor homologue (CHES-1-like), two genes encoding forkhead transcription factors that we discovered utilizing an integrated genetic, genomic and computational strategy for identifying novel genes expressed in the developing Drosophila heart. Both jumu and CHES-1-like are required during asymmetric cell division for the derivation of two distinct cardiac cell types from their mutual precursor, and in symmetric cell divisions that produce yet a third type of heart cell. jumu and CHES-1-like control the division of cardiac progenitors by regulating the activity of Polo, a kinase involved in multiple steps of mitosis. This pathway demonstrates how transcription factors integrate diverse developmental processes during organogenesis. GFP-positive and GFP-negative cells were profiled from Stage 11 TinD-GFP Drosophila embryos
Project description:Yap1 and its paralogue Taz largely control epithelial tissue growth. We have identified that hematopoietic stem cell (HSC) fitness response to stress depends on Yap1 and Taz. Deletion of Yap1 and Taz induces a loss of HSC quiescence, symmetric self-renewal ability and renders HSC more vulnerable to serial myeloablative 5-fluorouracil treatment. This effect depends on the predominant cytosolic polarization of Yap1 through its PDZ domain-mediated interaction with the scaffold Scribble. Scribble and Yap1 coordinate to control cytoplasmic Cdc42 activity and HSC fate determination in vivo. Deletion of Scribble disrupts Yap1 co-polarization with Cdc42 and decreases Cdc42 activity, resulting in increased selfrenewing HSC with competitive reconstitution advantages. These data suggest that Scribble/Yap1 co-polarization is indispensable for Cdc42- dependent activity on HSC asymmetric division and fate. The combined loss of Scribble, Yap1 and Taz results in transcriptional upregulation of Rac-specific guanine nucleotide exchange factors, Rac activation and HSC fitness restoration. Scribble links Cdc42 and the cytosolic functions of the Hippo signaling cascade in HSC fate determination.
Project description:Pre-effector and pre-memory cells resulting from the first CD8+ T cell division in vivo exhibit low and high rates of proteasome degradative activities, respectively. These proteasome-induced metabolic consequences were mediated in part by asymmetric segregation of Myc during cell division. Taken together, these results suggest proteasome activity as a regulator of CD8+ T lymphocyte metabolism and fate specification.
Project description:Aging organs functionally and structurally decline with the loss of their regenerative capabilities, yet the existence of distinct cell division programs that determine organ fates is unknown. Hair follicles, mammalian mini-organs that grow hair, miniaturize by aging. Here we report that hair follicle regeneration and aging are driven by distinct cell division types of hair follicle stem cells (HFSCs). Cell fate tracing and cell division axis analysis in mice revealed that HFSCs undergo symmetric and asymmetric cell divisions to generate a new bulge, yet preferentially provoke “stress-responsive type” asymmetric cell divisions that generate aberrantly differentiating cells upon age/stress. That dynamic program with repetitive divisions efficiently eradicates those cells through defective association and stabilization of a hemidesmosomal protein COL17A1 and a cell-polarity-protein aPKCλ in HFSCs, thereby causing organ aging. The forced stabilization of COL17A1 rescued organ aging through aPKCλ stabilization. These results demonstrate that distinct cell division programs govern tissue/organ fates.