Protein hormone fragmentation in intercellular signaling: hormones as nested information systems

This study explores the hypothesis that protein hormones are nested information systems in which initial products of gene transcription, and their subsequent protein fragments, before and after secretion and initial target cell action, play additional physiological regulatory roles. The study produced four tools and key results: (1) a problem approach that proceeds, with examples and suggestions for in vivo organismal functional tests for peptide-protein interactions, from proteolytic breakdown prediction to models of hormone fragment modulation of protein-protein binding motifs in unrelated proteins; (2) a catalog of 461 known soluble human protein hormones and their predicted fragmentation patterns; (3) an analysis of the predicted proteolytic patterns of the canonical protein hormone transcripts demonstrating near-universal persistence of 9 ± 7 peptides of 8 ± 8 amino acids even after cleavage with 24 proteases from four protease classes; and (4) a coincidence analysis of the predicted proteolysis locations and the 1939 exon junctions within the transcripts that shows an excess (P < 0.001) of predicted proteolysis within 10 residues, especially at the exonal junction (P < 0.01). It appears all protein hormone transcripts generate multiple fragments the size of peptide hormones or protein-protein binding domains that may alter intracellular or extracellular functions by acting as modulators of metabolic enzymes, transduction factors, protein binding proteins, or hormone receptors. High proteolytic frequency at exonal junctions suggests proteolysis has evolved, as a complement to gene exon fusion, to extract structures or functions within single exons or protein segments to simplify the genome by discarding archaic one-exon genes.

Asprosin and type 2 diabetes mellitus: a novel potential therapeutic implication

Diabetes is a group of metabolic disorders that is characterized by hyperglycemia which increases the risks of cardiovascular, microvascular, and macrovascular complications. Innovative therapeutic trials regarding diabetes control and management are continually being undertaken. The present review was aimed to explore the potential effects and mechanisms that lead to the pathogenesis of type 2 diabetes mellitus (T2DM) and its relation with asprosin. Asprosin is a newly discovered hormone that is encoded by protein fibrillin 1 (FBN1 gene), secreted by white adipose during fasting conditions at 5-10 nM levels, which acts on the liver through cell membrane receptors and activates the G protein cAMP- PKA pathway. Asprosin secretion is increased during fasting as the compensatory mechanism in hypoglycemia. Asprosin concentration is higher in patients with T2DM and impaired glucose regulation compared to healthy subjects. Genetic deficiency of asprosin may cause problems of poor appetite and extreme leanness in humans. Attenuating asprosin activity or depleting asprosin may serve as a novel therapeutic innovation for the treatment of T2DM and obesity. Hence, asprosin may serve as a beacon for the target of a future therapy in diabetes management.

Phylogenetic investigation of Peptide hormone and growth factor receptors in five dipteran genomes

Peptide hormones and growth factors bind to membrane receptors and regulate a myriad of processes in insects and other metazoans. The evolutionary relationships among characterized and uncharacterized ("orphan") receptors can provide insights into receptor-ligand biology and narrow target choices in deorphanization studies. However, the large number and low sequence conservation of these receptors make evolutionary analysis difficult. Here, we characterized the G-protein-coupled receptors (GPCRs), receptor guanylyl cyclases (RGCs), and protein kinase receptors (PKRs) of mosquitoes and select other flies by interrogating the genomes of Aedes aegypti, Anopheles gambiae, Culex quinquefasciatus, Drosophila melanogaster, and D. mojavensis. Sequences were grouped by receptor type, clustered using the program CLANS, aligned using HMMR, and phylogenetic trees built using PhyML. Our results indicated that PKRs had relatively few orphan clades whereas GPCRs and RGCs had several. In addition, more than half of the Class B secretin-like GPCRs and RGCs remained uncharacterized. Additional studies revealed that Class B GPCRs exhibited more gain and loss events than other receptor types. Finally, using the neuropeptide F family of insect receptors and the neuropeptide Y family of vertebrate receptors, we also show that functional sites considered critical for ligand binding are conserved among distinct family members and between distantly related taxa. Overall, our results provide the first comprehensive analysis of peptide hormone and growth factor receptors for a major insect group.