My. Mapara et al., G-PROTEIN SUBUNIT G-ALPHA-16 EXPRESSION IS RESTRICTED TO PROGENITOR B-CELLS DURING HUMAN B-CELL DIFFERENTIATION, Blood, 85(7), 1995, pp. 1836-1842
Recently G alpha 16, a new guanosine triphosphate (GTP) binding protei
n alpha subunit has been described to be specifically expressed in hum
an hematopoietic cells. Expression of G alpha 16 was observed in human
cell lines of myelomonocytic and T-lymphocytic origin, but not in hum
an B-cell lines Raji and IM9. We studied the expression of G alpha 16
in human B cells corresponding to different stages of B-cell different
iation by means of reverse transcriptase-polymerase chain reaction (RT
-PCR) and Western blotting. The human Burkitt's lymphoma cell lines Ra
ji, Ramos, BJAB, the lymphoblastoid cell line SKW6.4, and the plasmocy
toma cell line U266 were devoid of G alpha 16. In contrast, G alpha 16
was detected in the human progenitor B cell lines Reh and Nalm-6. Usi
ng the mu(+), k(-) cell line BLIN-1 (pre-B cell phenotype) and its der
ived subclone 1E8 (surface mu(+), k(+); B-cell phenotype) G alpha 16 e
xpression was found to disappear on transition from pre-B to B-cell di
fferentiation stage. The analysis of a broad panel of human neoplastic
B lymphocytes ranging from progenitor B-acute lymphatic leukemia (pre
-pre-B-ALL), common acute leukemias (cALL), pre-B-ALL, mature B-ALL to
low grade B-cell lymphoma (chronic lymphocytic leukemia of B-cell typ
e, leukemic centrocytic non-Hodgkins lymphoma [NHL], hairy cell leukem
ia) showed that G alpha 16 expression is limited to progenitor and pre
-B-ALL cells. Therefore, we conclude that within B-cell differentiatio
n, G alpha 16 is expressed solely during early B cell ontogeny and dow
nregulated during differentiation. Thus, G alpha 16 might be an import
ant regulator involved in signaling processes in progenitor B cells. (
C) 1995 by The American Society of Hematology.