High impact information on carboxylesterase

• With particular deletions, ges-1 was expressed, not as normally in the gut, but rather in muscle cells of the pharynx (which belong to a sister lineage of the gut) or in body wall muscle and hypodermal cells (which belong to a cousin lineage of the gut) [1].
• Using such a deleted ges-1 transgene as a biochemical marker of differentiation, we have investigated the basis of anterior-posterior gut patterning in C. elegans [2].
• In particular, the gut esterase ges-1 gene, which is normally expressed in all cells of the endoderm, is expressed only in the anterior-most gut cells when certain sequences in the ges-1 promoter are deleted [2].
• However, there is as yet no direct evidence that elt-2 does or does not control ges-1 [3].
• We have previously shown that a tandem pair of (A/T)GATA(A/G) sequences in the promoter region of the Caenorhabditis elegans gut esterase gene (ges-1) controls the tissue specificity of ges-1 expression in vivo [3].

Biological context of carboxylesterase

• For example, the C. elegans ges-1 5'-flanking region (as well as several introns) contains copies of three different SINE-like sequences, previously identified near the hsp-16 genes, near the unc-22 gene and in a repetitive element CeRep-3; none of these elements are found in the C. briggsae ges-1 gene [4].
• However, multiple copies of the GATA region are not able to repress the heat-induced expression of an hsp16-lacZ reporter gene, suggesting that the pharynx/tail repression mechanism is specific to the ges-1 environment [5].
• We use sequence alignments and subsequent deletions to identify a region at the 3'-end of both Ce-ges-1 and Ce-ges-1 that acts as the ges-1 cryptic pharynx enhancer whose activity is revealed by removal of the 5' WGATAR sites [6].
• The multiple facets of ges-1 expression provide an opportunity to investigate how a multicomponent organ system such as the digestive tract is established from diverse cell lineages [7].
• In the present paper, we show that elt-2 expression is completely gut specific, beginning when the embryonic gut has only two cells (one cell cycle prior to ges-1 expression) and continuing in every cell of the gut throughout the life of the worm [8].

Anatomical context of carboxylesterase

• We propose that, in the pharynx (and rectum), PHA-4 is normally bound to the ges-1 3'-enhancer sequence but that the activation function of PHA-4 is kept repressed by a (presently unknown) factor binding in the vicinity of the 5' WGATAR sites [6].
• Factors that bind to double-stranded oligonucleotides containing the ges-1 GATA sequences are present predominantly in nuclear extracts of embryos but are found neither in cytoplasmic nor in nuclear extracts of unfertilized oocytes [9].
• Here, we use both laser ablation experiments and genetic analysis to show that cells expressing the WGATAR-deleted ges-1 transgene belong to all three nongut lineages of the digestive tract: ABa, MS, and ABp [7].

Physical interactions of carboxylesterase

• We suggest that neither the elt-1 protein nor the skn-1 protein interacts directly with the ges-1 gene and that the observed binding proteins must correspond to products of other genes [9].

Other interactions of carboxylesterase

• The ges-1 esterases from the two nematodes are 83% identical at the amino acid level and contain regions of significant similarity to insect and mammalian esterases; these conserved regions can be identified with residues believed to be necessary for esterase function [4].
• However, we show that homozygous deficiency embryos (mDf7/mDf7 embryos and eDf19/eDf19 embryos, both of which lack the elt-1 gene, and nDf41/nDf41 embryos, which have no skn-1 gene), still express the ges-1 esterase [9].
• The gut esterase locus, denoted ges-1, maps less than 0.3 map units to the right of the unc-60 locus, at the left end of chromosome V [10].
• Moreover, the pharynx/tail expression of the WGATAR-deleted ges-1 transgene is abolished by mutations in the zygotic gene pha-4 [7].
• The gene was mapped close to the center of chromosome V (1.7 centimorgans to the left of dpy-11) and is therefore distinct from the gut esterase gene ges-1 [11].

Analytical, diagnostic and therapeutic context of carboxylesterase

• We have used isoelectric focusing analysis to demonstrate that, unlike the C. elegans ges-1 esterase, the A. suum enzyme is not restricted to the gut but is expressed in a wide range of tissues [12].

References