Worm Breeder's Gazette 14(3): 21 (June 1, 1996)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Wellcome Unit of Molecular Parasitology, Anderson College,University of Glasgow, Glasgow Gll 6NU, U.K.
(A/T)GATA(A/G) motifs have been previously noted upstream of a number of
cuticular collagen genes in C.elegans (Cox et al 1989) and we have
recently implicted such a motif in the regulation of dpy-7 by deletion
analysis of reporter gene constructs (Gilleard, Barry and Johnstone,
this issue). Since none of the currently identified C.elegans GATA
factors have been shown to be expressed in the post-embryonic hypodermis
(elt-1, elt-2 and end-1) I decided to look for new GATA factors using
PCR with degenerate primers. Nested primers across the Zinc finger
domain used in conjunction with an SL1 oligo identified a new family
member which I have called elt-3. One full length cDNA (cloned from Bob
Barstead's mixed stage library) is 1253bp in length (SL1 trans spliced)
and encodes a polypeptide of 226aa with a 490bp 3' UTR. A second cloned
cDNA of 1003bp (has a truncated 3' end which I suspect is an artefact
of oligo dT mispriming) has SQG in place of a C near the N terminus due
to an alternative splicing event at the 5' end of the second exon.
Further cDNAs are being examined to determine the relative abundance of
the alternative transcripts and determine whether any other forms exist.
The predicted polypeptide has a single GATA zinc finger
(C-X2-C-X17-C-X2-C) which is homologous to the C.terminal finger of "2
finger" GATA factors.
(The printed version contains a figure.)
The expression pattern of elt-3 has been studied using lac-Z and GFP
reporter gene fusions. The last of exon elt-3 was fused in frame with
lac-Z and GFP ( using Andy Fire's vectors pPd21-28 and pPd 95-67
respectively) and 4.5kb of 5' flanking sequence was included. Expression
is first seen in hypodermal cells in the pre-comma stage. This
expression is seen throughout subsequent embryogenesis and at each
postembryonic stage including the adult. Expression is seen in
hypodermal cells in the head and tail, hyp-7 and either P or V cells
(I'm not sure which of these yet but almost certainly not both). This
pattern is strikingly similar to day-7 and makes elt-3 a candidate as a
day-7 regulator. elt-3 is also expressed in two cells behind the pharynx
(either pharyngeal-intestinal valve cells or excretory gland cells) and
5 cells at the intestinal-rectal junction.
A number of reverse genetic (Tc-1 deletion derivatives,
anti-sense RNA) and ectopic expression experiments are currently being
performed to study the role of elt-3 both in hypodermal cell
differentiation and regulation of collagen gene expression.
Cox et al (1989) Gene, 76, 331-344.