Clinical medicine, mice knockout phenotypes and in vitro studies have shown that SP (specificity protein) transcription factors are important in many processes, including cell cycle regulation, apoptosis, metabolic regulation and oncogenesis. The SP family is united by a specific combination of three conserved Cys2His2 zinc fingers that form the DNA-binding domain and a Buttonhead (BTD) box CXCPXC, just N-terminal to the zinc fingers. Humans and mice have nine SP genes. C. elegans has 3 SP-related transcription factors:
sptf-1,
sptf-2 and
sptf-3. The gene structure of
sptf-1 has been confirmed by both the Japanese National Institute for Genetics and Harvard Medical School and the
sptf-2 gene structure by Harvard Medical School. Using RT-PCR we have identified two splice forms of
sptf-3, one having three additional upstream exons. We are currently investigating their functions in different stages of C. elegans development. We have made GFP fusion constructs to determine the expression patterns of
sptf-1 and
sptf-2 and from Ian Hopes laboratory we obtained transgenic animals carrying
sptf-2 and
sptf-3 GFP fusion constructs. In addition, we are making GFP fusion constructs for both forms of the
sptf-3 gene. Knockout animals have been generated by the Japanese Gene Knockout Consortium,
sptf-1(
tm784) and
sptf-3(
tm607) knockout animals show phenotypes that range from embryonic to larval lethality,
sptf-2(
tm1130) knockouts are viable. We have made transgenic animals carrying additional copies of the three sptf genes: sptf-1XS, sptf-2XS and sptf-3XS. We have observed effects on movement and body morphology in sptf-1XS, lethality and maternal sterility in sptf-2XS and growth defects in sptf-3XS transgenic animals. Genome wide RNAi screens have shown wild type phenotypes for
sptf-1 and
sptf-2 RNAi and a spectrum of mutant phenotypes for
sptf-3, comprising embryonic lethality, maternal sterility, abnormal locomotion and body morphology. We are carefully analyzing the phenotypes of all loss- and gain-of-function mutant animals to further characterize the functions of these three genes. .