Open AccessAlterations in the mir-15a/16-1 Loci Impairs Its Processing and Augments B-1 Expansion in De Novo Mouse Model of Chronic Lymphocytic Leukemia (CLL)
Author(s) -
Siddha Kasar,
Chingiz Underbayev,
Hassan Mohabatkar,
Ilko K. Ilev,
Heba Degheidy,
Steven R. Bauer,
Gerald E. Marti,
Carol S. Lutz,
Elizabeth Raveché,
Mona Batish
Publication year - 2016
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0149331
Subject(s) - congenic , biology , chronic lymphocytic leukemia , allele , mutation , microbiology and biotechnology , mutant , genetics , microrna , point mutation , phenotype , wild type , leukemia , gene
New Zealand Black (NZB) mice, a de novo model of CLL, share multiple characteristics with CLL patients, including decreased expression of miR-15a/16-1. We previously discovered a point mutation and deletion in the 3' flanking region of mir-16-1 of NZB and a similar mutation has been found in a small number of CLL patients. However, it was unknown whether the mutation is the cause for the reduced miR-15a/16-1 expression and CLL development. Using PCR and in vitro microRNA processing assays, we found that the NZB sequence alterations in the mir-15a/16-1 loci result in deficient processing of the precursor forms of miR-15a/16-1, in particular, we observe impaired conversion of pri-miR-15a/16-1 to pre-miR-15a/16-1. The in vitro data was further supported by derivation of congenic strains with replaced mir-15a/16-1 loci at one or both alleles: NZB congenic mice (N miR+/- ) and DBA congenic mice (D miR-/- ). The level of miR-15a/16-1 reflected the configuration of the mir-15a/16-1 loci with DBA congenic mice (D miR-/- ) showing reduced miR-15a levels compared to homozygous wild-type allele, while the NZB congenic mice (N miR+/- ) showed an increase in miR-15a levels relative to homozygous mutant allele. Similar to Monoclonal B-cell Lymphocytosis (MBL), the precursor stage of the human disease, an overall expansion of the B-1 population was observed in DBA congenic mice (D miR-/- ) relative to wild-type (D miR+/+ ). These studies support our hypothesis that the mutations in the mir-15a/16-1 loci are responsible for decreased expression of this regulatory microRNA leading to B-1 expansion and CLL development.