Project description:Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk subtype of B-ALL often associated with genetic variants that alter cytokine receptor signaling, including mutations in the interleukin-7 receptor (IL7R). To investigate whether IL7R variants are leukemia-initiating, we built mouse models expressing activated Il7r (aIL7R). B-cell intrinsic aIL7R mice developed spontaneous B-ALL, demonstrating sufficiency of Il7r activating mutations in leukemogenesis. Concomitant introduction of a knock-out allele in the associated adapter protein Lnk (encoded by Sh2b3) or a dominant-negative variant of the transcription factor Ikaros (Ikzf1) increased disease penetrance. The resulting murine leukemias displayed monoclonality and recurrent somatic Kras mutations and efficiently engrafted into immunocompetent mice. Phosphoproteomic analyses of aIL7R leukemic cells revealed constitutive Stat5 signaling and B cell receptor (BCR)-like signaling despite absence of surface pre-BCR. Finally, in vitro treatment of aIL7R leukemic B-cells with Jak, mTOR, or Syk inhibitors blocked growth, confirming that each pathway is active in this mouse model of IL7R-driven B-ALL.
Project description:Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk subtype of B-ALL often associated with genetic variants that alter cytokine receptor signaling, including mutations in the interleukin-7 receptor (IL7R). To investigate whether IL7R variants are leukemia-initiating, we built mouse models expressing activated Il7r (aIL7R). B-cell intrinsic aIL7R mice developed spontaneous B-ALL, demonstrating sufficiency of Il7r activating mutations in leukemogenesis. Concomitant introduction of a knock-out allele in the associated adapter protein Lnk (encoded by Sh2b3) or a dominant-negative variant of the transcription factor Ikaros (Ikzf1) increased disease penetrance. The resulting murine leukemias displayed monoclonality and recurrent somatic Kras mutations and efficiently engrafted into immunocompetent mice. Phosphoproteomic analyses of aIL7R leukemic cells revealed constitutive Stat5 signaling and B cell receptor (BCR)-like signaling despite absence of surface pre-BCR. Finally, in vitro treatment of aIL7R leukemic B-cells with Jak, mTOR, or Syk inhibitors blocked growth, confirming that each pathway is active in this mouse model of IL7R-driven B-ALL
Project description:Hybrids between species contain a mixture of two divergent proteomes, the combination of which may lead to dysfunctional protein-protein interactions. We performed an integrative study on hybrids between the swordtail fishes Xiphophorus malinche and Xiphophorus birchmanni, and found that the combination of X. birchmanni ndufs5 (a nuclear-encoded subunit of mitochondrial Complex I) with X. malinche mtDNA (which codes for multiple Complex I subunits) was lethal. We reasoned that if this lethality was due to dysfunctional protein-protein interactions in Complex I causing improper assembly, then in heterozygotes which possess one functional and one dysfunctional allele, the dysfunctional allele might be more likely to exist in an improperly integrated/folded state, and thus be more likely to be degraded by protein quality control mechanisms. This preferential degradation would be measurable as a bias in the proteome towards the compatible allele of ndufs5, and so we sought to measure the relative abundance of peptides derived from the X. malinche and X. birchmanni alleles of ndufs5 in hybrids heterozygous at ndufs5, with X. malinche ancestry in the mtDNA. Peptides derived from each allele are distinguishable by multiple amino acids, and we used heavy-labeled spike-ins to target multiple ndufs5 peptides from each species in 5 hybrids. We successfully detected one pair of birchmanni/malinche peptides, and compared their relative abundance using peak integration, then compared the ratio to that observed in the heavy-labeled spike-in, for which the true ratio was known. We found that the endogenous peptides were skewed towards the allele from the same species as the mtDNA (X. malinche), consistent with our hypothesis.
Project description:Here we investigate the possible relationship between the propagation of epigenetic information and the developmental cell proliferation during Xenopus embryogenesis. We systemically inhibited cell proliferation during the G1/S-transition in gastrula embryos and followed their development until the tadpole stage. We quantified by mass spectrometry the abundance of a large set of histone modification states, which reflects the developmental maturation of the embryonic epigenome.
Project description:Volume-regulated anion channels participate in the cellular response to osmotic swelling. These membrane proteins are heteromers of LRRC8 family members whose composition determines permeation properties. Although structures of the obligatory LRRC8A subunit have previously defined the architecture of VRACs, the organization of heteromeric channels has remained elusive. Here we have closed this gap by the structural characterization of channels consisting of LRRC8A and C. Like homomeric LRRC8A, these proteins assemble as hexamers. Despite the twelve possible arrangements, we find a single predominant species with an A/C ratio of two. In this assembly, the four LRRCA subunits cluster in their preferred conformation observed in homomers as pairs of closely interacting proteins that stabilize a closed state of the channel. In contrast, the two interacting LRRC8C-subunits show a larger flexibility, underlining their role in the destabilization of the tightly packed A subunits, thereby enhancing the activation properties of the protein.