High impact information on CyIIIa

• We utilized a fusion gene construct in which the bacterial chloramphenicol acetyl transferase (CAT) reporter gene is driven by CyIIIa actin regulatory sequences [1].
• We previously showed that the regulatory region that is included suffices to promote the accumulation of CAT mRNA in transgenic S. purpuratus embryos, on the same developmental schedule and in the same embryonic region, the aboral ectoderm, in which the CyIIIa actin gene is normally expressed (Flytzanis et al. 1987; Hough-Evans et al. 1987) [1].
• Through interactions within the middle module, SpMyb functions to repress activation of CyIIIa in the oral ectoderm and skeletogenic mesenchyme [2].
• The CyIIIa actin gene of Strongylocentrotus purpuratus is transcribed exclusively in the embryonic aboral ectoderm, under the control of 2.3 kb cis-regulatory domain that contains a proximal module that controls expression in early embryogenesis, and a middle module that controls expression in later embryogenesis [2].
• The 'middle module,' which lies upstream of the proximal module, acquires major control of CyIIIa function after the blastula stage [3].

Biological context of CyIIIa

• The CyIIIa.CAT fusion gene was injected into Strongylocentrotus purpuratus eggs, together with excess ligated competitor sequences representing subregions of the CyIIIa regulatory domain [4].
• Previous experiments have shown that the expression of a chimeric gene containing the CyIIIa promoter fused to a bacterial chloramphenicol actetyltransferase (CAT) gene is not confined to the correct cell lineage (aboral ectoderm) when injected into Lytechinus embryos [5].
• Most strikingly, the first intron of MTA contains elements not found in the MTB1 introns, including a consensus metal response element, an element A, and the P3A site demonstrated in the CyIIIa actin gene to be linked to the regulation of spatial expression [6].
• Comparison of both intron and 3'-terminal sequences shows that the CyIIIa and CyIIIb genes are closely related, while no homology in these untranslated sequences is observed between the CyIII genes and the other cytoskeletal actin genes of the S. purpuratus genome [7].
• Although CyIIIb exhibits strong nucleotide sequence similarity outside of coding DNA with the neighboring CyIIIa gene, it differs from that gene at six codons [8].

Anatomical context of CyIIIa

• In this paper, a negative regulatory element within this region was identified that is required for repression of the CyIIIa gene in skeletogenic mesenchyme cells [9].
• Its major role is to establish CyIIIa expression in the aboral ectoderm territory as the blastomere founder cells are specified and the oral-aboral axis is determined, and to activate the CyIIIa gene late in cleavage [3].
• A fusion gene construct in which the bacterial chloramphenicol acetyltransferase (CAT) gene is controlled by CyIIIa actin gene cis-regulatory sequences was injected into unfertilized eggs of the sea urchin Strongylocentrotus purpuratus [10].

Other interactions of CyIIIa

• SpZ12-1, a negative regulator required for spatial control of the territory-specific CyIIIa gene in the sea urchin embryo [9].
• The P3A1 factor also binds to a similar target sequence in a second gene, CyIIIa, expressed in embryonic aboral ectoderm [11].
• The functional genes CyIIIa and CyIIIb are linked at a 6 X 10(3)-base distance [7].
• The CyIIIa cytoskeletal actin gene of the sea urchin Strongylocentrotus purpuratus is activated in late cleavage and expressed exclusively in the aboral ectoderm territory of the embryo [9].

Analytical, diagnostic and therapeutic context of CyIIIa

• The affinity chromatography and identification of six different CyIIIa-regulatory factors is described, and the general utility of the method is discussed [12].

References