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: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:Caulobacter crescentus undergoes an asymmetric cell division controlled by a genetic circuit that cycles in space and time. We provide a universal strategy for defining the coding potential of bacterial genomes by applying ribosome profiling, RNA-seq, global 5’-RACE, and liquid chromatography coupled with tandem mass spectrometry (LC-MS) data to the 4-megabase C. crescentus genome. We mapped transcript units at single base-pair resolution using RNA-seq together with global 5’ RACE. Additionally, using ribosome profiling and LC-MS, we mapped translation start sites and coding regions with near complete coverage. We found most start codons lacked corresponding Shine-Dalgarno sites although ribosomes were observed to pause at internal Shine-Dalgarno sites within the ORF. These data suggest a more prevalent use of the Shine-Dalgarno sequence for ribosome pausing rather than translation initiation in C. crescentus. Overall 19% of the transcribed and translated genomic elements were newly identified or significantly improved by this approach providing a valuable genomic resource to elucidate the complete C. crescentus genetic circuitry that controls asymmetric cell division. Ribosome profiling and RNA-seq data were collected in Caulobacter crescentus NA1000 cells grown in M2G and PYE media to map transcript and ORF features in the genome.
Project description:Human tumors often contain slowly proliferating cancer cells that resist treatment but we do not know precisely how these cells arise. We show that rapidly proliferating cancer cells can divide asymmetrically to produce slowly proliferating “G0-like” progeny that are enriched following chemotherapy in breast cancer patients. Asymmetric cancer cell division results from asymmetric suppression of AKT/PKB kinase signaling in one daughter cell during telophase of mitosis. Moreover, inhibition of AKT signaling with small molecule drugs can induce asymmetric cancer cell division and the production of slow proliferators. Cancer cells therefore appear to continuously flux between symmetric and asymmetric division depending on the precise state of their AKT signaling network. This model may have significant implications for understanding how tumors grow, evade treatment, and recur. 3 replicates each of MCF7 Reactive Oxygen Species (ROS) high, HCT116 ROS high, MCF7 ROS low, and HCT116 ROS low.