The AMP-actviated protein kinase (AMPK) is a family of conserved proteins in nearly all eukaryotes. It is a heterotrimer composed of alpha, beta and gamma subunits that play an pivotal role in sensing intracellular ATP level to maintain the energy homeostasis within the cell. There are two AMPK alpha catalytic subunits in C. elegans, AAK-1 and AAK-2. Although they share high sequence homology, evidences suggested that AAK-2 played an important role in lifespan regulation, stress response and reproduction, while AAK-1 appears to be only participated in regulating germline development during dauer stage.To elucidate whether their different function may be due to distinct spatial and temporal patterns of their gene expression, we analyzed their gene expression patterns. Since
aak-1 and
aak-2 have two (
aak-1 a and b) and three (
aak-2 a, b and c) transripts, respectively, we first examined the relative abundence of these transcripts by using RT-qPCR. Our reslults revealed that
aak-1a and
aak-2c transcripts are much more abundant. In consistent with the RT-qPCR result, the transgenic worms expressing Paak-1a::gfp and
aak-2c::gfp showed much broader GFP expression compared to those of Paak-1b::gfp and
aak-2a/b::gfp. To our surprise, Paak-1a::gfp expression is even broader than Paak-2c::gfp expression. Paak-1a::gfp expression was also observed in some neurons at the head and tail, somatic gonad and M4, besides in ventral nerve cord, intestine, body wall muscle, pharynx, vulva, and excretory cell. While Paak-1b::gfp was only present in pharynx. Considering the broader expression pattern of
aak-1 compared to that of
aak-2, it is still not clear whether the difference in expression pattern is responsible for the functional difference of these two genes. Phenotypic analyses of
aak-1;
aak-2 double mutants indicated that absence of
aak-1 activity could further enhance some phenotypes of
aak-2 mutants, suggesting AAK-1 and AAK-2 may have redundant functions. Consistent with the previous results,
aak-1 expression driven by
aak-2c promoter could partially rescue
aak-1;
aak-2 mutant phenotypes. Given AMPK proteins are conserved in evolution, our results may help to understand the function of AMPK family proteins in other species.Key words: C. elegans, AMPK, expression, redundant function.