MicroRNAs in B cell development and malignancy

MicroRNAs are small RNA molecules that regulate gene expression and play critical roles in B cell development and malignancy. miRNA expression is important globally, as B cell specific knockouts of Dicer show profound defects in B cell development; and is also critical at the level of specific miRNAs. In this review, we discuss miRNAs that are involved in normal B cell development in the bone marrow and during B cell activation and terminal differentiation in the periphery. Next, we turn to miRNAs that are dysregulated during diseases of B cells, including malignant diseases and autoimmunity. Further study of miRNAs and their targets will lead to a better understanding of B cell development, and should also lead to the development of novel therapeutic strategies against B cell diseases

The lncRNA CASC15 regulates SOX4 expression in RUNX1-rearranged acute leukemia

Abstract Background Long non-coding RNAs (lncRNAs) play a variety of cellular roles, including regulation of transcription and translation, leading to alterations in gene expression. Some lncRNAs modulate the expression of chromosomally adjacent genes. Here, we assess the roles of the lncRNA CASC15 in regulation of a chromosomally nearby gene, SOX4, and its function in RUNX1/AML translocated leukemia. Results CASC15 is a conserved lncRNA that was upregulated in pediatric B-acute lymphoblastic leukemia (B-ALL) with t (12; 21) as well as pediatric acute myeloid leukemia (AML) with t (8; 21), both of which are associated with relatively better prognosis. Enforced expression of CASC15 led to a myeloid bias in development, and overall, decreased engraftment and colony formation. At the cellular level, CASC15 regulated cellular survival, proliferation, and the expression of its chromosomally adjacent gene, SOX4. Differentially regulated genes following CASC15 knockdown were enriched for predicted transcriptional targets of the Yin and Yang-1 (YY1) transcription factor. Interestingly, we found that CASC15 enhances YY1-mediated regulation of the SOX4 promoter. Conclusions Our findings represent the first characterization of this CASC15 in RUNX1-translocated leukemia, and point towards a mechanistic basis for its action

The Role of Long Non-coding RNAs in B-acute Lymphoblastic Leukemia

Non-coding RNAs play pivotal roles in a wide variety of molecular processes. The functions of long non-coding RNAs (lncRNAs), in particular, have deep implications for both development and oncogenesis. Dysregulated expression of lncRNAs has been found in various cancers, but had not been comprehensively described in B lymphoblastic leukemia (B acute lymphoblastic leukemia; B-ALL). We completed a gene expression profiling study in human B-ALL samples and found differential lncRNA expression in samples with particular cytogenetic abnormalities. We determined that lncRNA expression could discriminate between B-ALL with specific karyotype abnormalities as well as, predict patient survival. Two promising lncRNAs from our study, designated B-ALL associated long RNAs (BALRs), have the highest expression in B-ALL samples carrying the MLL rearrangement when compared non-MLL rearranged and normal CD19+ cells. MLL rearranged B-ALL cases have a very poor prognosis and occur frequently in infants, making them particularly difficult to treat. This thesis investigates the role of lncRNAs BALR-2 and BALR-6 in MLL translocated B-ALL. In the first part of this thesis work, we found that high expression of BALR-2 was correlated with diminished response to prednisone treatment. Knockdown led to a reduction in proliferation, increased apoptosis, and increased sensitivity to prednisolone treatment. Conversely, overexpression of the lncRNA caused increased cell growth and resistance to prednisone treatment. Remarkably, BALR-2 expression was repressed by prednisolone treatment and its dysregulation led to changes in the glucocorticoid response pathway in human and mouse B-cells. These findings indicate an important role for BALR-2 in the pathogenesis of B-ALL.Much like BALR-2, siRNA mediated knockdown of BALR-6 in human B-ALL cell lines caused decreased proliferation and increased apoptosis. Additionally, overexpression of BALR-6 isoforms caused a significant increase in progenitor populations in mice and increased proliferation in mammalian cell lines. To understand the functional role of BALR-6, differential expression analysis from cell lines with knockdown was carried out. The analysis indicated an enrichment of genes involved in leukemia. Among these genes were SP1 and its known target genes. Luciferase reporter assays uncovered a positive regulatory role for BALR-6 in SP1 mediated transcription. Together, these data elucidate a role for BALR-6 in transcriptional regulation.Thus, this thesis identifies novel non-coding RNA transcripts that regulate gene expression, and thereby pathogenesis in B-ALL with MLL rearrangement. This work suggests novel diagnostic, prognostic, and therapeutic utility for lncRNAs in B-ALL

MicroRNAs in B cell development and malignancy

Abstract MicroRNAs are small RNA molecules that regulate gene expression and play critical roles in B cell development and malignancy. miRNA expression is important globally, as B cell specific knockouts of Dicer show profound defects in B cell development; and is also critical at the level of specific miRNAs. In this review, we discuss miRNAs that are involved in normal B cell development in the bone marrow and during B cell activation and terminal differentiation in the periphery. Next, we turn to miRNAs that are dysregulated during diseases of B cells, including malignant diseases and autoimmunity. Further study of miRNAs and their targets will lead to a better understanding of B cell development, and should also lead to the development of novel therapeutic strategies against B cell diseases.</p

Trypanosoma cruzi calmodulin: Cloning, expression and characterization

1 - ArticleWe have cloned and expressed calmodulin (CaM) from Trypanosoma cruzi, for the first time, to obtain large amounts of protein. CaM is a very well conserved protein throughout evolution, sharing 100% amino acid sequence identity between different vertebrates and 99% between trypanosomatids. However, there is 89% amino acid sequence identity between T. cruzi and vertebrate CaMs. The results demonstrate significant differences between calmodulin from T. cruzi and mammals. First, a polyclonal antibody developed in an egg-yolk system to the T. cruzi CaM recognizes the autologous CaM but not the CaM from rat. Second, it undergoes a larger increase in the alpha-helix content upon binding with Ca(2+), when compared to CaM from vertebrates. Finally, two classic CaM antagonists, calmidazolium and trifluoperazine, capable of inhibiting the action of CaM in mammals when assayed on the plasma membrane Ca(2+) pump, showed a significant loss of activity when assayed upon stimulation with the T. cruzi CaM

LncRNA Expression Discriminates Karyotype and Predicts Survival in B-Lymphoblastic Leukemia

Long non-coding RNAs (lncRNAs) have been found to play a role in gene regulation with dysregulated expression in various cancers. The precise role that lncRNA expression plays in the pathogenesis of B-acute lymphoblastic leukemia (B-ALL) is unknown. Therefore, unbiased microarray profiling was performed on human B-ALL specimens and it was determined that lncRNA expression correlates with cytogenetic abnormalities, which was confirmed by RT-qPCR in a large set of B-ALL cases. Importantly, high expression of BALR-2 correlated with poor overall survival and diminished response to prednisone treatment. In line with a function for this lncRNA in regulating cell survival, BALR-2 knockdown led to reduced proliferation, increased apoptosis, and increased sensitivity to prednisolone treatment. Conversely, overexpression of BALR-2 led to increased cell growth and resistance to prednisone treatment. Interestingly, BALR-2 expression was repressed by prednisolone treatment and its knockdown led to upregulation of the glucocorticoid response pathway in both human and mouse B-cells. Together, these findings indicate that BALR-2 plays a functional role in the pathogenesis and/or clinical responsiveness of B-ALL and that altering the levels of particular lncRNAs may provide a future direction for therapeutic development. IMPLICATIONS: lncRNA expression has the potential to segregate the common subtypes of B-ALL, predict the cytogenetic subtype, and indicate prognosis