I. Sanchezgarcia et al., FUNCTIONAL DIVERSITY OF LIM PROTEINS - AMINO-TERMINAL ACTIVATION DOMAINS IN THE ONCOGENIC PROTEINS RBTN1 AND RBTN2, Oncogene, 10(7), 1995, pp. 1301-1306
The RBTN1 and RBTN2 genes are activated by distinct translocations inv
olving chromosome 11 in some T cell acute leukaemias. The RBTN protein
s belong to the LIM family which comprises proteins with one, two or t
hree cysteine-rich LIM domains, sometimes together with homeodomains o
r protein kinase domains. The RBTN1 and RBTN2 proteins comprise only t
andem LIM domains. We report that RBTN1 and RBTN2 proteins are capable
of supporting transcriptional transactivation of specific reporter ge
nes in transfection assays. The results, using intact proteins or fusi
ons with the homeodomain of the heterologous protein Isl-1, show that
this transcriptional activation ability resides in the NH2-terminal pa
rts of both proteins. The use of yeast assays with RBTN2 shows that RB
TN2 forms homodimers and that the NH2-terminal 27 amino acids are suff
icient to facilitate transcriptional transactivation. These data expan
d the functional diversity of the LIM-domain protein family and they a
ugment the previously defined relationship between chromosomal translo
cations and transcriptional activation.