Three different prohormones yield a variety of Hydra-RFamide (Arg-Phe-NH2) neuropeptides in Hydra magnipapillata.
The freshwater polyp Hydra is the most frequently used model for the study of development in cnidarians. Recently we isolated four novel Arg-Phe-NH2 (RFamide) neuropeptides, the Hydra-RFamides I-IV, from Hydra magnipapillata. Here we describe the molecular cloning of three different preprohormones from H. magnipapillata, each of which gives rise to a variety of RFamide neuropeptides. Preprohormone A contains one copy of unprocessed Hydra-RFamide I (QWLGGRFG), II (QWFNGRFG), III/IV [(KP)HLRGRFG] and two putative neuropeptide sequences (QLMSGRFG and QLMRGRFG). Preprohormone B has the same general organization as preprohormone A, but instead of unprocessed Hydra-RFamide III/IV it contains a slightly different neuropeptide sequence [(KP)HYRGRFG]. Preprohormone C contains one copy of unprocessed Hydra-RFamide I and seven additional putative neuropeptide sequences (with the common N-terminal sequence QWF/LSGRFGL). The two Hydra-RFamide II copies (in preprohormones A and B) are preceded by Thr residues, and the single Hydra-RFamide III/IV copy (in preprohormone A) is preceded by an Asn residue, confirming that cnidarians use unconventional processing signals to generate neuropeptides from their precursor proteins. Southern blot analyses suggest that preprohormones A and B are each coded for by a single gene, whereas one or possibly two closely related genes code for preprohormone C. Northern blot analyses and in situ hybridizations show that the gene coding for preprohormone A is expressed in neurons of both the head and foot regions of Hydra, whereas the genes coding for preprohormones B and C are specifically expressed in neurons of different regions of the head. All of this shows that neuropeptide biosynthesis in the primitive metazoan Hydra is already rather complex.
Darmer
D
D
Department of Cell Biology and Anatomy, Zoological Institute, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen O, Denmark.
Hauser
F
F
Nothacker
H P
HP
Bosch
T C
TC
Williamson
M
M
Grimmelikhuijzen
C J
CJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D015870:Gene Expression / Q000235:genetics; D006829:Hydra / Q000737:chemistry*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000096:biosynthesis / Q000737:chemistry*; D011498:Protein Precursors / Q000737:chemistry; D016372:RNA, Antisense / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA
D009479:Neuropeptides; D011498:Protein Precursors; D016372:RNA, Antisense; D012333:RNA, Messenger; C058047:arginylphenylalaninamide