Download ePoster - Endocrine Abstracts

Discovery and localisation of the expression of calcitonin-type
and CRH-type neuropeptide precursors in an echinoderm
Weigang Cai, Michaela Egertová, Yusef Badi, Dean Semmens, Maurice R. Elphick
School of Biological & Chemical Sciences, Queen Mary University of London Email: [email protected]
INTRODUCTION
Chordata
Echinodermata
•Neuropeptides are neuronal signalling molecules that have been characterised in vertebrates
and some invertebrate species (e.g the protostomian invertebrates Drosophila and C. elegans).
•Studies on deuterostomian invertebrates such as echinoderms (e.g. starfish) can bridge the
“evolutionary gap” between protostomian invertebrates and the vertebrates.
•Calcitonin and Corticotropin-Releasing- Hormone (CRH) have well known physiological roles in
vertebrates, but little is known about the functions of these hormones in invertebrates
•Here we used mRNA in situ hybridization to investigate the expression patterns of calcitonintype and CRH-type precursors in the starfish Asterias rubens.
Arthropoda
Nematoda
Mollusca
Deuterostomes Protostomes
ANIMAL PHYLOGENY
Annelida
Cnidaria
Calcitonin-type precursor
CRH-type precursor
Asterias rubens calcitonin-type precursor (ArCTP). Predicted signal peptide; putative CT-type
peptide; C-terminal glycine (G) residue, putative substrate for amidation; putative dibasic cleavage
sites (* = stop codon).
Asterias rubens CRH-type precursor (ArCRHP). Predicted signal peptide; putative CRH-type
peptide; C-terminal glycine (G) residue, putative substrate for amidation; putative dibasic cleavage
site (* = stop codon).
Alignment of ArCRH with other CRH-type peptides
Alignment of ArCT with other calcitonin-type peptides
a
amide
amide
amide
amide
amide
amide
amide
amide
Localisation of:
ArCTP mRNA
a
a
a
a
a
a
a
a
ArCRHP mRNA
STARFISH ANATOMY
a
a
b
c
b
d
ArCTP mRNA expression pattern
e
f
g
ArCRHP mRNA expression pattern
e
f
c
d
g
h
ArCTP mRNA expression in Asterias rubens. Circumoral nerve ring (a); Radial nerve cord
ArCRHP mRNA expression in Asterias rubens. Circumoral nerve ring (ectoneural) (a);
(transverse) (b); Radial nerve cord (longitudinal) (c); Pyloric stomach (d); Cardiac stomach (e);
Pyloric caecae (f); Coelomic epithelium (g)
Radial nerve cord (ectoneural) (b, transverse; c, longitudinal); Marginal nerve (d); Pyloric and
cardiac stomach (e, f); Pyloric caecae (g); Coelomic epithelium (h).
METHODS
• ArCTP and ArCRHP were identified using A. rubens neural transcriptome sequence data.
• cDNAs encoding ArCTP and ArCRHP were cloned and sequenced from A. rubens radial nerve cDNA.
• Starfish (A. rubens) were fixed with 4% paraformaldehyde and decalcified in Morse’s solution.
• Fixed animals (arms, disk) were embedded in paraffin wax and sectioned using a microtome.
• DIG-labelled probes complementary to ArCTP and ArCRHP were used for mRNA in situ hybridization.
Acknowledgements
CONCLUSIONS
• Cells expressing ArCTP in ectoneural and hyponeural regions of the radial nerve cords and
circumoral nerve ring, cardiac and pyloric stomachs, coelomic epithelium and pyloric caecae.
• Cells expressing ArCRHP in ectoneural region of the radial nerve cords and circumoral nerve ring,
marginal nerves, coelomic epithelium, cardiac and pyloric stomachs and pyloric caecae.
• This is the first study of the expression of calcitonin- and CRH-type precursors in an echinoderm.
• These data provide a basis for investigation of the physiological roles of calcitonin-type and CRHtype neuropeptides in starfish.