title: XEpac, a guanine nucleotide-exchange factor for Rap GTPase, is a novel hatching gland specific marker during the Xenopus embryogenesis.
abstract: cAMP is a second messenger controlling various cellular processes through cAMP-dependent protein kinase (cAPK, PKA) and cyclic nucleotide-gated ion channels. Recently, the PKA-independent-cAMP-mediated signaling pathway by means of exchange protein directly activated by cAMP (Epac) has been demonstrated. Epac is a guanine nucleotide-exchange factor (GEF) for Rap, a Ras-like small GTPase. To investigate this new target for cAMP in development, we have isolated Xepac, the Xenopus laevis homologue of Epac by cDNA library screening. Xepac (Xepac1) encodes 890 amino acids, which have 57% identity with human Epac1 and 59% with that of rat Epac1 in amino acids. Whole-mount in situ hybridization and reverse transcriptase-polymerase chain reaction analysis show that XEpac is expressed both maternally and zygotically and is restricted within the developing hatching gland. Intriguingly, overexpression of XEpac induces the anterior markers XAG-1 and XOtx2 and can convert ectoderm into cement- and hatching gland-expressing cells. These results suggest that XEpac contains anterior positional information.
authors.affiliation: Division of Molecular and Life Sciences, Pohang University of Science and Technology, Hyoja Dong, Pohang, Kyungbuk, 790-784, Republic of Korea.
authors.forename: Seung Joon
authors.initials: SJ
authors.lastname: Lee
authors.forename: Jin-Kwan
authors.initials: JK
authors.lastname: Han
mesh_terms: D000818:Animals; D005088:Exocrine Glands / Q000166:cytology / Q000196:embryology*; D020662:Guanine Nucleotide Exchange Factors / Q000096:biosynthesis*; D015398:Signal Transduction / Q000502:physiology*; D029867:Xenopus Proteins / Q000096:biosynthesis*; D014982:Xenopus laevis
chemical_list: D020662:Guanine Nucleotide Exchange Factors; C503364:XEpac1 protein, Xenopus; D029867:Xenopus Proteins