Deregulation of Ikaros expression in B-1 cells: New insights in the malignant transformation to chronic lymphocytic leukemia. Issue 3 (12th July 2019)

• Record Type: Journal Article
• Authors: de Oliveira, Vivian Cristina; de Lacerda, Marcelo Pitombeira; Moraes, Bárbara Bomfim Muniz; Gomes, Caio Perez; Maricato, Juliana Terzi; Souza, Olivia Fonseca; Schenkman, Sergio; Pesquero, João Bosco; Moretti, Nilmar Silvio; Rodrigues, Celso Arrais; Popi, Ana Flavia
• Is Part Of: Journal of leukocyte biology. Volume 106:Issue 3(2019)
• Page Start: 581
• Page End: 594
• Publication Date: 2019-07-12
• Subjects: B-1 and CLL cells -- BCR signaling -- Ikaros; Leucocytes -- Periodicals; Reticulo-endothelial system -- Periodicals; 571.96
• DOI: 10.1002/JLB.MA1118-454R
• Languages: English
• ISSNs: 0741-5400

Abstract

Abstract: Chronic lymphocytic leukemia (CLL) is a chronic form of leukemia that originates from an abnormal expansion of CD5 + B-1 cells. Deregulation in the BCR signaling is associated with B-cell transformation. Contrariwise to B-2 cells, BCR engagement in B-1 cells results in low proliferation rate and increased apoptosis population, whereas overactivation may be associated with lymphoproliferative disorders. It has been demonstrated that several transcription factors that are involved in the B cell development play a role in the regulation of BCR function. Among them, Ikaros is considered an essential regulator of lymphoid differentiation and activation. Several reports suggest that Ikaros expression is deregulated in different forms of leukemia. Herein, we demonstrated that CLL cells show decreased Ikaros expression and abnormal cytoplasmic cell localization. These alterations were also observed in radioresistant B-1 cells, which present high proliferative activity, suggesting that abnormal localization of Ikaros could determine its loss of function. Furthermore, Ikaros knockdown increased the expression of BCR pathway components in murine B-1 cells, such as Lyn, Blnk, and CD19. Additionally, in the absence of Ikaros, B-1 cells become responsive to BCR stimulus, increasing cell proliferation even in the absence of antigen stimulation. These results suggested that Ikaros is an important controller of B-1 cell proliferation by interfering with the BCR activity. Therefore, altered Ikaros expression in CLL or radioresistant B-1 cells could determine a responsive status of BCR to self-antigens, which would culminate in the clonal expansion of B-1 cells. Graphical Abstract: Alteration in Ikaros expression interferes with BCR signaling and increases B-1 cell proliferation, which could be related to malignant transformation to CLL.