Stephanie Lecaude

University of Denver, Denver, CO, United States

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Publications (14)47.76 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Analyses of prodynorphin and proenkephalin cDNAs cloned from the central nervous system of the shark, Heterodontus portusjacksoni, provided additional evidence that these two opioid precursor-coding genes were most likely directly derived from a common ancestral gene. The two cDNAs could be aligned by inserting only seven gaps. The prodynorphin cDNA encodes five opioid sequences which could be aligned to opioid positions B through F in the proenkephalin cDNA. The sequence identity within the opioid positions was 59% at the amino acid level. Shark α-neo-endorphin, dynorphin A, and dynorphin B have amino acid motifs in common with shark met-enkephalin-8, and shark proenkephalin opioid positions E and F, respectively, which have not been observed in other gnathostome prodynorphin and proenkephalin precursor sequences. Shark prodynorphin encodes both kappa (α-neo-endorphin, dynorphin A, and dynorphin B) and delta (met-enkephalin and leu-enkephalin) opioid sequences. Mixed function prodynorphin precursors (encoding both enkephalins and dynorphins) are also found in representatives of the teleost fishes, lungfishes, and amphibians. It appears that only mammals evolved a prodynorphin precursor that exclusively encodes kappa opioid agonists (dynorphins).
    General and Comparative Endocrinology 12/2011; 177(3):353-64. · 2.82 Impact Factor
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    ABSTRACT: In gnathostomes the kappa, mu, delta, ORL-1 receptor genes constitute the opioid/ORL-1 receptor gene family. These genes are most likely the result of two (2R) genome duplication events that occurred during the radiation of the chordates. In stilico analysis of the genome of the lamprey, Petromyzon marius, revealed the partial sequences of four genes that may be the result of a lineage specific genome duplication event in the lamprey lineage. The sequencing of cDNAs from the lamprey CNS supports the assumption that these putative lamprey opioid-like receptor genes are expressed by lamprey neurons. Analysis of gnathostome ORL-1 receptor sequences support the hypothesis that the ORL-1 gene has undergone a transition from an opioid receptor that could bind several types of opioid ligands to a receptor in mammals that can only be activated by the FGGF form of the orphanin ligand.
    Annals of the New York Academy of Sciences 07/2010; 1200:85-94. · 4.38 Impact Factor
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    ABSTRACT: In gnathostomes there is remarkable consistency in the organization of the proenkephalin gene. This opioid precursor encodes seven opioid (YGGF) sequences: five pentapeptide sequences, a met-enkephalin-7 sequence and a met-enkephalin-8 sequence. Yet, within vertebrate lineages there can be distinct sets of pentapeptide opioids (YGGFM or YGGFL). In the Sarcopterygii, the sixth opioid position in lungfishes and anuran amphibian proenkephalin genes encodes a met-enkephalin (YGGFM) sequence. However, in mammalian proenkephalin there is a leu-enkephalin (YGGFL) sequence at this position. This study was done to test the hypothesis that the presence of the leu-enkephalin sequence in mammals is a feature common to amniote vertebrates, but not present in anamniote vertebrates. To resolve this issue, proenkephalin cDNAs were cloned from the urodele amphibians, Amphiuma means and Necturus maculosus, and two amniote vertebrates, the turtle, Chrysemys scripta, and the brown snake, Storeria dekayi. As predicted, a met-enkephalin sequence is present at the sixth opioid position in urodele amphibians; whereas, a leu-enkephalin sequence is present at this opioid site in the reptile proenkephalin sequences. These data are consistent with the conclusion that the transition from a met-enkephalin sequence to a leu-enkephalin sequence at the sixth opioid position in tetrapod proenkephalins occurred in the ancestral proto-reptiles. Phylogenetic analyses, using the Maximum Parsimony and Neighbor-Joining algorithms, of the amphibian proenkephalin sequences supported the position that anuran and urodele amphibians are a monophyletic assemblage. The same analysis of reptile-related proenkephalin sequences, including the deduced amino acid sequence of a partially characterized alligator proenkephalin cDNA, could not conclusively resolve the phylogeny of the major reptilian orders.
    General and Comparative Endocrinology 01/2007; 153(1-3):189-97. · 2.82 Impact Factor
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    ABSTRACT: The detection of the prodynorphin gene in anuran amphibians and lungfishes may indicate that this gene arose as a result of the duplication of the proenkephalin gene early during the divergence of the Sarcopterygii, or that this gene may predate the divergence of the ray-finned fish and the lobe-finned fish. The cloning of prodynorphin-related genes from the pufferfish and zebrafish supports the latter hypothesis. This study analyzes trends in the radiation of the prodynorphin gene in teleosts. Prodynorphin cDNAs were cloned from the brain of the eel Anguilla rostrata and the Nile tilapia, Oreochromis niloticus. These teleost prodynorphin sequences have distinct alpha-neoendorphin, dynorphin A, and dynorphin B sequences, and a novel opioid sequence, YGGFI. The relationship of these teleost prodynorphin sequences to other actinopterygian and sarcopterygian prodynorphin sequences will be discussed.
    Peptides 05/2006; 27(4):797-804. · 2.52 Impact Factor
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    ABSTRACT: Proopiomelanocortin (POMC) cDNAs were cloned and sequenced from brain extracts of two species of urodele amphibians: Amphiuma means and Necturus maculosus. Although the two species of urodele amphibians belong to separate families, and do not share a direct common ancestor, the level of primary sequence identity for the open reading of the POMC cDNAs was 90% at the amino acid level and 79% at the nucleotide level. It appears that the POMC gene in these urodele amphibians has been accumulating mutations at the amino acid level at a slower rate than the POMC gene in other sarcopterygian orders.
    Peptides 11/2005; 26(10):1920-8. · 2.52 Impact Factor
  • Robert M Dores, Stephanie Lecaude
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    ABSTRACT: The POMC gene is perhaps the most extensively studied member of the opioid/orphanin gene family. In Phylum Chordata this gene has been characterized in representatives of every class within the Gnathostomata, as well as in one representative agnathan vertebrate, the marine lamprey. This review provides a systematic overview of trends in the evolution of the melanocortins (ACTH/alpha-MSH, beta-MSH, gamma-MSH, and delta-MSH) and beta-endorphin in gnathostomes, and advances the hypothesis that the appearance of gamma-MSH occurred early in the radiation of the gnathostomes. A summary of the extensive work on POMC genes in the marine lamprey is also provided, as well as a reevaluation of the conserved regions in the sequence of CLIP (corticotropin-like-intermediate lobe peptide) in the POMC sequences of the various groups of gnathostomes.
    General and Comparative Endocrinology 06/2005; 142(1-2):81-93. · 2.82 Impact Factor
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    ABSTRACT: The opioid/orphanin gene family provides a model system for analyzing the outcomes of genome duplication events. Recent studies on the proenkephalin gene provide additional evidence that the organizational plan for this gene has been conserved throughout the extensive radiation of the gnathostome vertebrates. However, an analysis of the amino acid sequence of proenkephalin from the zebrafish, Danio rerio, suggests that novel forms of this opioid precursor may be evolving in teleosts. Analyses of sarcopterygian prodynorphin sequences revealed a proenkephalin signature in prodynorphin. Current studies on the opioid/orphanin gene family point to the duplication events that shaped this family occurring prior to the radiation of the gnathostomes.
    Annals of the New York Academy of Sciences 05/2005; 1040:22-37. · 4.38 Impact Factor
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    ABSTRACT: In mammals the opioids Met-enkephalin and Leu-enkephalin are derived from a common precursor, proenkephalin, and as a result these neuropeptides are co-localized in enkephalinergic neurons. The mammalian scheme for enkephalinergic networks is not universal for all classes of sarcopterygian vertebrates. In an earlier study, distinct Met- and Leu-enkephalin-positive neurons were detected in the central nervous system (CNS) of the African lungfish, Protopterus annectens. More recently, characterization of proenkephalin cDNAs separately cloned from the CNS of P. annectens and the Australian lungfish, Neoceratodus forsteri, revealed that the proenkephalin gene in these species encodes only Met-enkephalin-related opioids. In the current study a full-length prodynorphin cDNA (accession No. AY 445637) was cloned and sequenced from the CNS of N. forsteri. In addition to encoding alpha-neoendorphin, dynorphin A and dynorphin B sequences unique to the lungfish, two Leu-enkephalin sequences, flanked by paired basic amino acid proteolytic cleavage sites, were detected in this precursor. The partial sequence of a P. annectens prodynorphin cDNA (accession No. AY445638) also encoded a Leu-enkephalin sequence and a novel YGGFF sequence. The presence of the Leu-enkephalin sequence in the lungfish prodynorphin precursors would explain the origin of the distinct Leu-enkephalin-positive neurons found in the African lungfish CNS. The realization that Met-enkephalin and Leu-enkephalin can be derived from distinct opioid-coding precursor genes calls into question the interpretation of comparative immunohistochemical studies that have mapped 'enkephalinergic' networks in non-mammalian vertebrates.
    Neuroendocrinology 02/2004; 79(4):185-96. · 3.54 Impact Factor
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    ABSTRACT: There is general agreement that the polypteriform fishes, like Polypterus senegalus, constitute a unique lineage in the evolution of the vertebrates. However, the precise position of these fishes had been a point of controversy since the time of Darwin and Huxley. There is now consensus that the polypteriform fishes are members of superorder Actinopterygii. However, within the Actinopterygii, it is still debatable as to whether the polypteriform fishes are an early offshoot of the Actinopterygii or a more recent sister group to the sturgeon and other extant chondrostean fishes. In this study the sequence of proopiomelanocortin (POMC), the common precursor for the melanocortins and beta-endorphin, was used to evaluate the phylogenetic position of the polypteriform fishes relative to other bony fishes. 3(')RACE and 5(')RACE protocols were used to amplify overlapping regions of a POMC cDNA from the brain of P. senegalus. The full-length POMC cDNA had an open reading frame that encoded 259 amino acids. As seen in most gnathostomes, P. senegalus POMC has three melanocortin sequences (ACTH/alpha-MSH, gamma-MSH, and beta-MSH), and a beta-endorphin region. For phylogenetic analysis, the following POMC sequences were aligned at the amino acid level and analyzed using a maximum parsimony algorithm: P. senegalus, dogfish, sturgeon A, paddlefish A, sockeye salmon A, tilapia, and gar. The dogfish POMC sequence was used as the out-group. In this analysis the P. senegalus POMC sequence formed a clade with the chondrostean POMC sequences (sturgeon A and paddlefish A), and not with the neopterygian sequences (sockeye salmon A, tilapia, and gar). P. senegalus POMC is remarkably similar to sturgeon POMC A. In particular, in both precursors there is evidence for degeneration at the proteolytic cleavage site that precedes the gamma-MSH sequence. Based on the analysis of this nuclear gene it would appear that P. senegalus belongs to a branch of the chrondrostean lineage rather than representing a lineage of ray-finned fish that is ancestral to the chondrostean and neoptyergian ray-finned fishes. Alternatively, if the polypteriform fishes are in fact an early offshoot of the Actinopterygii (the traditional view), then the observations made for P. senegalus POMC relative to the chondrostean POMC sequences is the result of convergence.
    General and Comparative Endocrinology 01/2004; 134(3):339-46. · 2.82 Impact Factor
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    ABSTRACT: Since a fourth MSH sequence, delta-MSH, has been detected in the proopiomelanocortin (POMC) gene of a dogfish and a stingray, members of superorder Squalea (class Chondrichthyes), it is possible that this novel MSH sequence might be a feature common to the POMC genes of all modern sharks and rays. As an initial step towards addressing this question, a full-length POMC cDNA was cloned and sequenced from the pituitary of the Port Jackson shark, Heterodontus portusjacksoni. The Port Jackson shark represents one of the oldest lineages in superorder Galea, and this superorder together with superorder Squalea form infraclass Neoselachii (the extant sharks and rays). The Port Jackson shark POMC cDNA has an open reading frame that is 1032 nucleotides in length and encodes the deduced amino acids sequences for beta-endorphin, ACTH/alpha-MSH, beta-MSH, gamma-MSH, and delta-MSH. Port Jackson shark delta-MSH has 83% primary sequence identity with dogfish and stingray delta-MSH, and it appears that the delta-MSH sequence may have been the result of an internal domain duplication and reinsertion of the beta-MSH sequence. The presence of the delta-MSH sequence in the POMC genes of representatives of both superorders of infraclass Neoselachii would indicate that the delta-MSH sequence must have been present in the ancestral euselachian shark that gave rise to the neoselachian radiation.
    General and Comparative Endocrinology 09/2003; 133(1):71-9. · 2.82 Impact Factor
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    ABSTRACT: Advances in molecular biology have made it possible to rapidly obtain the amino acid sequence of neuropeptide precursors-either by cloning and sequencing the cDNA that encodes the precursor, or by reconstructing the arrangement of exons and introns in a neuropeptide-coding gene through genomic approaches. The databases generated from these molecular approaches have been used to design probes to identify the cells that express the gene, or to ascertain the rate of expression of the gene, and even to predict the post-translational modifications that can generate functional neuropeptides from a biologically inert precursor. Although the power of these approaches is substantial, it is appreciated that a gene sequence or an mRNA sequence reflects the potential products that may be assembled in a secretory cell. To understand the functional capabilities of the secretory cell, the molecular genetics approaches must be combined with procedures that actually characterize the end-products generated by the secretory cell. Recent advances in two-dimensional gel electrophoresis and mass spectrometry now make it possible to analyze neuropeptides from a relatively small amount of tissue. These procedures can reveal novel end-products, tissue-specific endoproteolytic cleavage events, and developmental shifts in post-translational processing schemes. A gene family that illustrates all of these processes and the advantages of combining genomics with proteomics is the opioid/orphanin gene family.
    Mass Spectrometry Reviews 01/2002; 21(4):220-43. · 7.74 Impact Factor
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    ABSTRACT: Analyzing the Radiation of the Proenkephalin Gene in Tetrapods: Cloning of a Bombina orientalis Proenkephalin cDNA: A proenkephalin cDNA was cloned from the brain of the anuran amphibian, Bombina orientalis (Family: Discoglossidae). This cDNA is 1358 nucleotides in length, and contains an open reading frame that codes for 251 amino acids. Within the open reading frame there are seven opioid (YGGF) sequences. There were five Met-enkephalin (YGGFM) sequences that are flanked by sets of paired basic amino acid proteolytic cleavage sites and two C-terminally extended Met-enkephalin sequences: YGGFMRGY and YGGFMRF. No Leu-enkephalin sequences were found in B. orientalis proenkephalin. It was possible to align the amino acid sequences of proenkephalin from several vertebrate taxa (human, Australian lungfish, B. orientalis, Xenopus laevis, Spea multiplicatus) by inserting a minimum of nine gaps. This alignment was then used to analyze the corresponding nucleotides for each proenkephalin sequence using maximum likelihood. This analysis yielded a single tree. In this tree, the Australian lungfish sequence was the outgroup or the tetrapod ingroup. The amphibian sequences form a clade separate from the human sequence. The bootstrap value for the amphibian clade was 100%. Within the amphibian clade the Bombina sequence was the sister group to a clade composed of the X. laevis and S. multiplicatus sequences. The bootstrap value for the X. laevis/S. multiplicatus clade was 94%. Collectively, these data indicate that the sequence of Bombina proenkephalin may be more similar to the proposed ancestral anuran proenkephalin sequence, than either X. laevis or S. multiplicatus proenkephalin.
    Peptides 01/2002; 22(12):2021-5. · 2.52 Impact Factor
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    ABSTRACT: Cloning of a proenkephalin cDNA from the pelobatid anuran amphibian, Spea multiplicatus, provides additional evidence that Leu-enkephalin, although present in the brain of anuran amphibians, is not encoded by the proenkephalin gene. The S. multiplicatus proenkephalin cDNA is 1375 nucleotides in length, and the open reading frame contains the sequences of seven opioid sequences. There are five copies of the Met-enkephalin sequence, as well as an octapeptide opioid sequence (YGGFMRNY) and a heptapeptide opioid sequence (YGGFMRF). In the proenkephalin sequence of S. multiplicatus the penultimate opioid is a Met-enkephalin sequence rather than the Leu-enkephalin present in mammalian sequences. The same order of opioid sequences also is observed for the proenkephalin sequence of the pipid anuran amphibian, Xenopus laevis. Hence, from a phylogenetic standpoint the organization of tetrapod proenkephalin has been remarkably conserved. What remains to be resolved is whether the Leu-enkephalin sequence found in mammalian proenkephalin is an ancestral trait or a derived trait for the tetrapods. Unlike the proenkephalin precursor of X. laevis, all of the opioid sequences in the S. multiplicatus proenkephalin cDNA are flanked by paired-basic amino acid proteolytic cleavage sites. In this regard the proenkephalin sequence for S. multiplicatus is more similar to mammalian proenkephalins than the proenkephalin sequence of X. laevis. However, a comparison of the proenkephalin sequences in human, X. laevis, and S. multiplicatus revealed several conserved features in the evolution of the tetrapod proenkephalin gene. By contrast, a comparison of tetrapod proenkephalin sequences with the partial sequence of a sturgeon proenkephalin cDNA indicates that the position occupied by the penultimate opioid sequence in vertebrate proenkephalins may be a highly variable locus in this gene.
    Peptides 04/2000; · 2.52 Impact Factor
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    ABSTRACT: A degenerate primer, specific for the opioid core sequence YGGFM, was used to clone and sequence proopiomelanocortin (POMC) cDNAs from the brain of the African lungfish, Protopterus annectens, and from the brain of the western spadefoot toad, Spea multiplicatus. In addition, the opioid-specific primer was used to clone and sequence a 3'RACE product corresponding to a portion of the open reading frame of S. multiplicatus proenkephalin. For both species, cDNA was made from a single brain and a degenerate opioid-specific primer provided a reliable probe for detecting opioid-related cDNAs. The African lungfish POMC cDNA was 1,168 nucleotides in length, and contained regions that are similar to tetrapod POMCs and fish POMCs. The African lungfish POMC encodes a tetrapod-like gamma-MSH sequence that is flanked by sets of paired basic amino acid proteolytic cleavage sites. The gamma-MSH region in ray-finned fish POMCs either has degenerate cleavage sites or is totally absent in some species. However, the African lungfish gamma-MSH sequence does contain a deletion which has not been observed in tetrapod gamma-MSH sequences. The beta-endorphin region of lungfish POMC has the di-amino acid sequence tryptophan-aspartic acid in the N-terminal region and an additional glutamic acid residue in the C-terminal region of beta-endorphin - features found in fish beta-endorphin, but not tetrapod beta-endorphins. The western spadefoot toad POMC was 1,186 nucleotides in length, and exhibited an organizational scheme typical for tetrapod POMCs. However, the toad POMC did lack a paired basic amino acid proteolytic cleavage site N-terminal to the beta-MSH sequence. Thus, like rat POMC, it is doubtful that beta-MSH is an end product in either the toad brain or intermediate pituitary. At the amino acid level, the toad POMC had 76% sequence identity with Xenopus laevis POMC and 68% sequence identity with Rana ribidunda POMC. The use of these POMC sequences to assess phylogenetic relationships within anuran amphibians will be discussed. With respect to the fragment of S. multiplicatus proenkephalin cDNA, two metenkephalin sequences and the metenkephalin-RF sequence were found encoded in this fragment. As seen for X. laevis and R. ridibunda proenkephalin, a leuenkephalin sequence was not detected in the C-terminal region of the S. multiplicatus proenkephalin. The absence of a leuenkephalin sequence may be a common feature of anuran amphibian proenkephalins.
    Neuroendocrinology 08/1999; 70(1):43-54. · 3.54 Impact Factor

Publication Stats

231 Citations
47.76 Total Impact Points


  • 2000–2011
    • University of Denver
      • Department of Biological Sciences
      Denver, CO, United States
  • 2010
    • University of Colorado
      • Division of Radiological Sciences
      Denver, CO, United States
  • 2006
    • Kuwait University
      • Department of Biological Sciences
      Kuwait, Muhafazat al `Asimah, Kuwait