Component of the set-2/ash-2 histone methyltransferase (HMT) complex (Probable). Required for the di- and trimethylation at 'Lys-4' of histone H3, a mark associated with epigenetic transcriptional activation (PubMed:21527717, PubMed:20555324). Implicated in the epigenetic inheritance of lifespan over several generations (PubMed:22012258). Functions as transcriptional regulator (PubMed:28379943). Acts in the germline to limit the longevity of the soma, probably by regulating a lipid metabolism pathway that signals from the germline to the intestine, thereby preventing accumulation of mono-unsaturated fatty acids (PubMed:20555324, PubMed:22012258, PubMed:28379943). Component of the SET2 complex (also known as the SET1/COMPASS complex), which contains at least set-2, swd-2.1, cfp-1, rbbp-5, wdr-5.1, dpy-30 and ash-2 (Probable) (PubMed:31602465). Within the complex, interacts with cfp-1 and wdr-5.1 (PubMed:31602465). Expressed in somatic and germline tissues (at protein level). Expressed throughout development and in adult animals. Decreased levels of tri- and dimethylated 'Lys-4' of histone H3 in the somatic cells in embryos and young adult animals (PubMed:21527717, PubMed:20555324). Increased dimethylated 'Lys-4' of histone H3 in primordial germ cells (PubMed:21527717). Decreased dimethylated 'Lys-4' of histone H3 in the distal region of the germline (PubMed:21527717). Reduced fertility (PubMed:21527717). RNAi-mediated knockdown results in the extension of lifespan (PubMed:20555324). Decreased levels of trimethylated 'Lys-4' of histone H3 in L3 stage larvae (PubMed:20555324). Leads to a deregulation of fat metabolism and to an accumulation of mono-unsaturated fatty acids in the intestine (PubMed:28379943).