Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Jan 1;106(1):306-309.
doi: 10.3324/haematol.2019.245795.

FcγRIIb-BCR coligation inhibits BCR signaling in chronic lymphocytic leukemia

Rosa Bosch  1 , Alba Mora  1 , Carolina Cuellar  2 , Gerardo Ferrer  3 , Sergey Gorlatov  4 , Josep Nomdedéu  5 , Emili Montserrat  6 , Jorge Sierra  2 , Kanti R Rai  3 , Nicholas Chiorazzi  3 , Carol Moreno  2
Affiliations

FcγRIIb-BCR coligation inhibits BCR signaling in chronic lymphocytic leukemia

Rosa Bosch et al. Haematologica. .
No abstract available

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Molecular effects of B-cell receptor (BCR) ligation or FcγRIIb-BCR co-ligation in chronic lymphocytic leukemia cells with responsive BCR. (A) Immunoblot for two representative chronic lymphocytic leukemia (CLL) patient’s samples that responded to BCR ligation. Purified B cells from CLL patients were exposed to F(ab’)2 anti-human immunoglubin M (IgM) (10 mg/mL) and whole anti-human IgM (15 mg/mL) polyclonal antibodies (pAb) or specific anti-human FcγRIIb monoclonal antibody (2B6) (1 mg/mL) for 5 minutes before being lysed and immunoblotted for p-ITIM domain of FcγRIIb, p-SHIP, p-AKT and p-ERK. Equal loading was checked by immunoblotting with GAPDH (n=9). (B) Immunoblot analyses of SHIP in membrane fraction extracts of CLL cells from two representative patient’s samples. The remaining extract containing cytosolic fraction of non-treated cells was used as control. The absence of GAPDH expression indicated no cytosolic contamination of the membrane fraction. Cadherin was used as a membrane fraction marker, as well as a control for protein loading. (C) Bar charts show mean values and standard deviation for the relative expression of p-ITIM, p-SHIP, p-AKT and p-ERK in CLL patients with responsive BCR (n=9). P-values were calculated using two tail paired t-test (*P<0.05, **P<0.01, ***P<0.001). F: F(ab’)2 anti-human IgM pAb; W: whole anti-human IgM pAb; 2B6: specific antihuman FcγRIIb monoclonal antibody.
Figure 2.
Figure 2.
Involvement of SHIP in the inhibitory effect of FcγRIIb-B-cell receptor coligation on chronic lymphocytic leukemia cells. (A) Relative SHIP expression in chronic lymphocytic leukemia (CLL) B cells transfected with short intefering RNA (siRNA) SHIP-1 (n=3). (B) Relative AKT and ERK phosphorylation in SHIP-1 siRNA transfected (n=3) and non-transfected (n=9) CLL B cells. (C) Immunoblot for a representative CLL patient’s sample transfected or not transfected with siRNA SHIP-1. (D) Immunoblot for a representative CLL patient’s sample exposed to 10 mM of 3AC or EtOH. F(ab’)2 fragments of anti-human immunoglobulin M (IgM) (10 mg/mL) or whole anti-human IgM (15 mg/mL) polyclonal antibodies (pAb) were used to ligate the BCR alone or to coligate it with FcγRIIb, respectively. Cells were lysed and immunoblotted for SHIP, p-SHIP, p-AKT and p-ERK. Equal loading was checked by immunoblotting with GAPDH. Mean values, standard deviation and statistical significance between data were determined by two-tailed paired t-test (*P<0.05, **P<0.01). F: F(ab’)2 anti-human IgM pAb; W: whole antihuman IgM pAb; 2B6: specific anti-human FcγRIIb monoclonal antibody.
Figure 3.
Figure 3.
Activation, apoptosis and proliferation of chronic lymphocytic leukemia cells upon B-cell receptor (BCR) ligation or FcγRIIb-BCR coligation. (A) Calcium kinetics for a representative chronic lymphocytic leukemia (CLL) patient’s sample in which purified leukemic cells were loaded with Indo1 ratio and acquired for 60 seconds prior to the addition of F(ab’)2 anti-immunoglobulin M (anti-IgM), whole anti-IgM or anti-FcγRIIb. (B) Box plots represents the median mean fluorescence intensity ratio of Indo1 (4 mM) for each stimuli in CLL patient’s samples (n=10). Purified B cells from CLL patients with responsive BCR were exposed to the indicated stimuli for 48 hours (h) or 72h and then analyzed by flow cytometry for CD69 expression on viable cells (B), Annexin V and TO-PROR-3 (Annexin V+ cells were considered apoptotic cells) (C) or EdU incorporation using the Click-iTTM EdU Alexa FluorTM 488 Flow Cytometry Assay Kit (D) (n=10). Box plots encompass the data points within 1.5-times the interquartile range from the first or third quartile. P-values were calculated using two tail paired t-test (*P<0.05, **P<0.01). F: F(ab’)2 anti-human IgM ployclonal antibodies (pAb); W: whole anti-human IgM pAb; 2B6: specific anti-human FcγRIIb monoclonal antibody.
See this image and copyright information in PMC

References

    1. Stevenson FK, Krysov S, Davies AJ, Steele AJ, Packham G. B-cell receptor signaling in chronic lymphocytic leukemia. Blood. 2011; 118(16):4313-4320. - PubMed
    1. Muta T, Kurosaki T, Misulovin Z, Sanchez M, Nussenzweig MC, Ravetch JV. A 13-amino-acid motif in the cytoplasmic domain of Fc gamma RIIB modulates B-cell receptor signalling. Nature. 1994;368(6466):70-73. - PubMed
    1. Phillips NE, Parker DC. Cross-linking of B lymphocyte Fc gamma receptors and membrane immunoglobulin inhibits antiimmunoglobulin- induced blastogenesis. J Immunol. 1984; 132(2):627-632. - PubMed
    1. Guarini A, Chiaretti S, Tavolaro S, et al. BCR ligation induced by IgM stimulation results in gene expression and functional changes only in IgV H unmutated chronic lymphocytic leukemia (CLL) cells. Blood. 2008;112(3):782-792. - PubMed
    1. Petlickovski A, Laurenti L, Li X, et al. Sustained signaling through the B-cell receptor induces Mcl-1 and promotes survival of chronic lymphocytic leukemia B cells. Blood. 2005;105(12):4820-4827. - PubMed

Publication types

MeSH terms

Substances