Characterization of mouse epithelial protein lost in neoplasm (EPLIN) and comparison of mammalian and zebrafish EPLIN

EPLIN is a cytoskeleton-associated protein that was initially identified as the product of a gene that is transcriptionally down-regulated in cancer c ells. In human, there are two known isoforms, EPLIN-alpha and -beta, genera ted by alternative promoter usage from a single gene. With the exception of a single LIM (lin-11, isl-1, and mec-3) domain, the sequence of EPLIN is u nique and does not provide any clues to its function. To identify conserved regions of EPLIN that may be important for its function, we have character ized mouse (m) and zebrafish (zf) EPLIN. As in human, two isoforms, the 593 aa mEPLIN-alpha (77% identity; 83% similarity) and 753 aa mEPLIN-beta (75% identity: 83% similarity), were present in mouse, mEPLIN-alpha is highly e xpressed in embryonic tissue and adult lung and spleen, whereas mEPLIN-beta is preferentially expressed in kidney, testis, lung and liver. The analysi s of mEPLIN gene revealed that the overall organization of the exons in mou se and human are conserved. In zebrafish, there was only one form, the 629 aa zfEPLIN, corresponding to the mammalian EPLIN-beta. Like its mammalian c ounterparts, ectopically expressed zfEPLIN is co-localized to the actin cyt oskeleton. While the overall homology between mammalian and zebrafish EPLIN was not striking (37% identity; 50% similarity), there were seven highly c onserved regions, which should be useful in structure-function studies of t his novel protein. (C) 2001 Elsevier Science B.V. All rights reserved.