ABSTRACT
Somatic loss of function mutations in cohesin genes are frequently associated with various cancer types, while cohesin disruption in the germline causes cohesinopathies such as Cornelia-de-Lange syndrome (CdLS). Here, we present the discovery of a recurrent heterozygous RAD21 germline aberration at amino acid position 298 (p.P298S/A) identified in three children with lymphoblastic leukemia or lymphoma in a total dataset of 482 pediatric cancer patients. While RAD21 p.P298S/A did not disrupt the formation of the cohesin complex, it altered RAD21 gene expression, DNA damage response and primary patient fibroblasts showed increased G2/M arrest after irradiation and Mitomycin-C treatment. Subsequent single-cell RNA-sequencing analysis of healthy human bone marrow confirmed the upregulation of distinct cohesin gene patterns during hematopoiesis, highlighting the importance of RAD21 expression within proliferating B- and T-cells. Our clinical and functional data therefore suggest that RAD21 germline variants can predispose to childhood lymphoblastic leukemia or lymphoma without displaying a CdLS phenotype.
Subject(s)
Cell Cycle Proteins , DNA-Binding Proteins , Lymphoma , Precursor Cell Lymphoblastic Leukemia-Lymphoma , Apoptosis , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Line, Tumor , Child , DNA-Binding Proteins/genetics , De Lange Syndrome/genetics , G2 Phase Cell Cycle Checkpoints , Germ Cells/metabolism , Humans , Lymphoma/genetics , Mutation , Phenotype , Precursor Cell Lymphoblastic Leukemia-Lymphoma/geneticsABSTRACT
While the shelterin complex guards and coordinates the mechanism of telomere regulation, deregulation of this process is tightly linked to malignant transformation and cancer. Here, we present the novel finding of a germline stop-gain variant (p.Q199*) in the shelterin complex gene POT1, which was identified in a child with acute myeloid leukemia. We show that the cells overexpressing the mutated POT1 display increased DNA damage and chromosomal instabilities compared to the wildtype counterpart. Protein and mRNA expression analyses in the primary patient cells further confirm that, physiologically, the variant leads to a nonfunctional POT1 allele in the patient. Subsequent telomere length measurements in the primary cells carrying heterozygous POT1 p.Q199* as well as POT1 knockdown AML cells revealed telomeric elongation as the main functional effect. These results show a connection between POT1 p.Q199* and telomeric dysregulation and highlight POT1 germline deficiency as a predisposition to myeloid malignancies in childhood.
Subject(s)
Genetic Predisposition to Disease/genetics , Leukemia, Myeloid, Acute/genetics , Myeloproliferative Disorders/genetics , Shelterin Complex/genetics , Telomere-Binding Proteins/genetics , Adult , DNA Damage/genetics , Germ Cells , Germ-Line Mutation/genetics , HEK293 Cells , Humans , Myeloid Cells , RNA, Messenger/genetics , Telomere/genetics , Young AdultABSTRACT
N-terminal (Nt) acetylation is a highly prevalent co-translational protein modification in eukaryotes, catalyzed by at least five Nt acetyltransferases (Nats) with differing specificities. Nt acetylation has been implicated in protein quality control, but its broad biological significance remains elusive. We investigate the roles of the two major Nats of S. cerevisiae, NatA and NatB, by performing transcriptome, translatome, and proteome profiling of natAΔ and natBΔ mutants. Our results reveal a range of NatA- and NatB-specific phenotypes. NatA is implicated in systemic adaptation control, because natAΔ mutants display altered expression of transposons, sub-telomeric genes, pheromone response genes, and nuclear genes encoding mitochondrial ribosomal proteins. NatB predominantly affects protein folding, because natBΔ mutants, to a greater extent than natA mutants, accumulate protein aggregates, induce stress responses, and display reduced fitness in the absence of the ribosome-associated chaperone Ssb. These phenotypic differences indicate that controlling Nat activities may serve to elicit distinct cellular responses.
Subject(s)
Acetyltransferases/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/metabolism , AcetylationABSTRACT
BACKGROUND: Isolated myelosarcoma of infancy is a rare presentation of acute myelogenous leukaemia (AML). Because of its rarity and early onset in infancy underlying genetic predisposition is potentially relevant in disease initiation. METHODS AND RESULTS: We report an oncologic emergency in an infant with thoracic and intraspinal aleukaemic myeloid sarcoma causing acute myelon compression and lower leg palsy. Whole-exome sequencing of the patient's germline DNA identified a rare PALB2 (OMIM 610355) variant (p.A1079S), which is located in a domain critical for the gene's proper function within the homology-directed repair pathway. In line with potential DNA damage repair defects mediated by the PALB2 deregulation, the patient's fibroblasts showed increased sensitivity towards radiation and DNA intercalating agents. CONCLUSION: Therefore, we suggest PALB2 p.A1079S as a pathogenic variant potentially contributing to the here observed patient phenotype.