AP-1 is a hetero-tetrameric adaptor complex which recruits clathrin during post-Golgi vesicle formation. It has been identified as crucial in various trafficking routes from yeast to human cells, but it is also implicated in development as shown by the embryonic lethality induced in mice and worms when AP-1 is mutated. In order to better understand the developmental role of AP-1, we have decided to identify new AP-1 interactors. In C. elegans, AP-1 total loss of function leads to an embryonic arrest at the 2-fold stage (Shim et al., MBC, 11, 2743). However, there are two copies of the <font face=symbol>m</font> subunit, UNC-101 and APM-1, and the total loss of function of only one of these subunits leads to a partial AP-1 loss of function. In particular, the null allele
unc-101(
sy108) induces only a partial larval lethality; but a synthetic embryonic lethality occurs when RNAi against
apm-1 is done is an
unc-101(
sy108) background (Shim et al., MBC, 11, 2743). Based on these results, we conducted a genome-wide RNAi screen to identify genetic enhancers of the Unc-101 phenotype. Several interactors of
unc-101(
sy108) have been identified and confirmed by a secondary screen in a strain carrying the
unc-101(
m1) mutation. These interactors include the already known
dab-1 gene, a small GTPase of the Rab family and a protein implicated in Notch signalling, as well as
cdc-48.1 and
cdc-48.2. In order to identify interactors specific of
unc-101, versus those interacting also with
apm-1, we are also trying to isolate a null mutant of
apm-1. We will use the MosTIC technique (Robert & Bessereau, EMBO J, 26, 170) starting with a strain carrying a Mos1 insertion in an
apm-1 intron generated by the C. elegans transposon insertion project (Granger et al. NAR, 32,
e117). Preliminary experiments indicate that the Muv phenotype associated with the strain carrying
apm-1(cxTi9732) is not due to the Mos1 insertion in
apm-1.