The restoration of catalytic activity to mutant enzymes by small molecules is well-established for in vitro systems. Here we show that the protein tyrosine kinase Src R388A mutant can be rescued in live cells using the small molecule imidazole. Cellular rescue of a v-Src homolog was rapid and reversible and conferred predicted oncogenic properties. Using chemical rescue in combination with mass spectrometry, six known Src kinase substrates were confirmed, and several new protein targets identified. Chemical rescue data suggests that c-Src is active under basal conditions. Rescue of R388A c-Src also allowed contributions of Src to the MAP kinase pathway to be clarified. This chemical rescue approach is likely to be of broad utility in cell signaling.
Chemical rescue of a mutant enzyme in living cells.
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View SamplesThe regulation of multipotent cardiac progenitor cell (CPC) expansion and subsequent differentiation into cardiomyocytes, smooth muscle, or endothelial cells is a fundamental aspect of basic cardiovascular biology and cardiac regenerative medicine. However, the mechanisms governing these decisions remain unclear. Here, we show that Wnt/-Catenin signaling, which promotes expansion of CPCs, is negatively regulated by Notch1-mediated control of phosphorylated -Catenin accumulation within CPCs, and that Notch1 activity in CPCs is required for their differentiation. Notch1 positively, and -Catenin negatively, regulated expression of the cardiac transcription factors, Isl1, Myocd and Smyd1. Surprisingly, disruption of Isl1, normally expressed transiently in CPCs prior to their differentiation, resulted in expansion of CPCs in vivo and in an embryonic stem (ES) cell system. Furthermore, Isl1 was required for CPC differentiation into cardiomyocyte and smooth muscle cells, but not endothelial cells. These findings reveal a regulatory network controlling CPC expansion and cell fate that involve unanticipated functions of -Catenin, Notch1 and Isl1 that may be leveraged for regenerative approaches involving CPCs.
A regulatory pathway involving Notch1/beta-catenin/Isl1 determines cardiac progenitor cell fate.
Specimen part
View SamplesFull title: Genomics based analysis of interactions between developing B-lymphocytes and stromal cells reveal complex interactions and two-way communication
Genomics based analysis of interactions between developing B-lymphocytes and stromal cells reveal complex interactions and two-way communication.
Specimen part
View SamplesThe function of ID4 in CLL development was studied in vivo using TCL1 transgenic mouse model that develop leukemia similar to human CLL. TCL1 mice with ID4 single knockout gene have accelerated CLL progression.
Silencing of the inhibitor of DNA binding protein 4 (ID4) contributes to the pathogenesis of mouse and human CLL.
Specimen part
View SamplesAfter positive selection in the thymus, the newly generated single positive (SP) thymocytes are phenotypically and functionally immature and undergo apoptosis upon antigen stimulation. In the thymic medullary microenvironment, SP cells progressively acquire immunocompetence. Negative selection to remove autoreactive T cells also occur at this stage. We have defined four subsets of CD4 SP, namely, SP1, SP2, SP3, and SP4 that follow a functional maturation program and a sequential emergence during mouse ontogeny.
The molecular signature underlying the thymic migration and maturation of TCRαβ+ CD4+ CD8 thymocytes.
Specimen part
View SamplesOrigins of the brain tumor, medulloblastoma, from stem cells or restricted pro-genitor cells are unclear. To investigate this, we activated oncogenic Hedgehog signaling in multipotent and lineage-restricted CNS progenitors. We observed that normal unipo-tent cerebellar granule neuron precursors (CGNP) derive from hGFAP+ and Olig2+ rhombic lip progenitors. Hedgehog activation in a spectrum of early and late stage CNS progenitors generated similar medulloblastomas, but not other brain cancers, indicating that acquisition of CGNP identity is essential for tumorigenesis. We show in human and mouse medulloblastoma that cells expressing the glia-associated markers Gfap and Olig2 are neoplastic and that they retain features of embryonic-type granule lineage progenitors. Thus, oncogenic Hedgehog signaling promotes medulloblastoma from lineage-restricted granule cell progenitors.
Acquisition of granule neuron precursor identity is a critical determinant of progenitor cell competence to form Shh-induced medulloblastoma.
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View SamplesCD38, a multi-functional membrane receptor and enzyme, consumes NAD+ to generate products such as cyclic-ADP-ribose. CD38 knockout mice show elevated tissue and blood NAD+ level. Chronic feeding of high-fat, high-sucrose diet to wild type mice leads to exercise intolerance and reduced metabolic flexibility. Loss of CD38 by genetic mutation protects mice from diet-induced metabolic deficit. These animal model results suggest that elevation of tissue NAD+ through genetic ablation of CD38 can profoundly alter energy homeostasis in animals that are maintained on a calorically-excessive Western diet.
Genetic Ablation of CD38 Protects against Western Diet-Induced Exercise Intolerance and Metabolic Inflexibility.
Specimen part
View SamplesAffymetrix Human Gene 1.1 ST Array profiling of 285 primary medulloblastoma samples.
Subgroup-specific structural variation across 1,000 medulloblastoma genomes.
Sex, Age
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