SpHE

Function

The SpHE gene is one of a set of genes expressed zygotically only at the very early blastula (VEB) stage.
SpHE encodes hatching enzyme, a member of the collagenase family (Reynolds et al., 1992).

Protein

SpHE is a metalloendoprotease (Reynolds et al., 1992).

Subcellular location

Cytoplasmic

Expression Pattern

The VEB genes are the earliest activated genes identified that encode strictly zygotic products.
SpHE mRNA is undetectable in the egg.
RNAase protection assay, which can detect as few as 10 transcripts per embryo indicated that SpHE transcripts begin to accumulate at 4-8-cell stage.
RNA blot analysis demonstrate that the SpHE transcripts reach peak abundance from 9 hours (128 cells) to 15 hours (250 cells) post-fertilization and disappear by mesenchyme blastula stage (25 hours postfertilization).
Solution titration indicates that there are approximately 150,000 SpHE transcripts per embryo at 12 hours.
In situ hybridization showes that in 12-hour embryos the VEB transcripts always accumulate in presumptive ectoderm but to a variable extent in cells of the endoderm and mesenchymal lineages (Reynolds et al., 1992).

mRNA level

Temporal accumulation
Method: RNAase protection assay (up to 64 cells)
Reference: Reynolds et al., 1992
Method: RNA blot analysis
Reference: Reynolds et al., 1992

Stage Egg 4-8 cells 16 cells 32 cells 64 cells 9h 12h 15h 25h

Level - + + + + + + + -

Sequences

GenBank:

promoter

Regulatory Regions

Promoter structure

Regulatory Connections

Upstream Genes

SpOtx SpEts4

SpHE

Downstream Genes

Evolutionary Homologues

HE6 Paracentrotus lividus

Links

Urchin Web

Bibliography

UrchiNet

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Stage	Egg	4-8 cells	16 cells	32 cells	64 cells	9h	12h	15h	25h
Level	-	+	+	+	+	+	+	+	-