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Identification of cDNA encoding motilin related peptide/ghrelin precursor from dog fundus
C Tomasetto1, C Wendling, M C Rio
1Institut de génétique et de Biologie Moléculaire et Cellulaire, 1 rue Laurent Fries 67404, Illkirch cedex, France.
Abstract:
A novel protein expressed by entero-endocrine cells of the mouse stomach was named prepromotilin Related Peptide (ppMTLRP) since it shares sequence similarities with the prepromotilin (Tomasetto et al.). The mouse ppMTLRP was found identical to the rat precursor of ghrelin (ppghrelin), an endogenous ligand specific for the Growth Hormone Secretagogue receptor identified from rat stomach (Kojima et al.). In the present study the cDNA encoding the dog counterpart of ppMTLRP/Ghrelin has been isolated and sequenced. The dog ppMTLRP/Ghrelin cDNA showed scores of respectively 80% and 75% homology with its human and mouse counterparts. By translation of the dog ppMTLRP/Ghrelin cDNA sequences, two ORFs could be deduced encoding either a 117 amino acid ppMTLRP/Ghrelin or the deleted Gln14 ppMTLRP/Ghrelin, as it was also known in mouse, rat and man. The dog ppMTLRP/Ghrelin shared 91% similarity and 78% identity, and 89% similarity and 78% identity with the human and mouse ppMTLRP/Ghrelin proteins respectively. The best score of homology was found in the MTLRP/Ghrelin sequence itself. Indeed the dog MTLRP/Ghrelin peptide shared 100% similarity and 93% identity, and 96% identity and similarity, with the human and mouse MTLRP/Ghrelin. Using Northern blot analysis to study dog ppMTLRP/Ghrelin gene expression on dog adult gut tissues, maximal expression level was found in the stomach fundus and corpus, and no expression could be detected in the stomach antrum nor in the duodenum, jejunum, ileum, colon or liver. In conclusion, we have identified ppMTLRP/Ghrelin from dog, and found that it is highly conserved with man, mouse or rat. The expression pattern along the gastro-intestinal tract is similar to the expression pattern previously described in mouse.
Insights
Researchers identified dog prepromotilin Related Peptide (ppMTLRP)/Ghrelin, finding it highly conserved across species. Its gene expression in dogs is concentrated in the stomach fundus and corpus, mirroring patterns seen in mice.
Area of Science:
- Endocrinology
- Molecular Biology
- Comparative Genomics
Background:
- Entero-endocrine cells produce novel peptides like prepromotilin Related Peptide (ppMTLRP).
- Mouse ppMTLRP is identical to rat ghrelin precursor (ppghrelin), an endogenous Growth Hormone Secretagogue receptor ligand.
- Ghrelin and its precursors play significant roles in regulating growth hormone secretion and appetite.
Purpose of the Study:
- To isolate and sequence the dog counterpart of ppMTLRP/Ghrelin.
- To analyze the sequence homology of dog ppMTLRP/Ghrelin with human, mouse, and rat counterparts.
- To investigate the gene expression pattern of dog ppMTLRP/Ghrelin in the gastro-intestinal tract.
Main Methods:
- cDNA isolation and sequencing of the dog ppMTLRP/Ghrelin.
- Bioinformatic analysis for sequence homology and protein translation.
- Northern blot analysis for gene expression studies in canine gut tissues.
Main Results:
- Dog ppMTLRP/Ghrelin cDNA showed 80% homology with human and 75% with mouse counterparts.
- Two open reading frames (ORFs) were deduced, encoding a 117 amino acid ppMTLRP/Ghrelin and a variant.
- Dog ppMTLRP/Ghrelin protein exhibited high similarity and identity with human and mouse orthologs, especially in the mature MTLRP/Ghrelin sequence (100% similarity with human).
- Maximal gene expression was observed in the stomach fundus and corpus, with no detectable expression in other gut segments or the liver.
Conclusions:
- Dog ppMTLRP/Ghrelin has been identified and is highly conserved among mammals.
- The expression pattern of dog ppMTLRP/Ghrelin in the gastro-intestinal tract is similar to that observed in mice.
- This study provides insights into the evolutionary conservation and tissue-specific expression of ghrelin precursors in canines.