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De La Toba EA, Anapindi KDB, Sweedler JV. Assessment and Comparison of Database Search Engines for Peptidomic Applications. J Proteome Res 2023; 22:3123-3134. [PMID: 36809008 PMCID: PMC10440370 DOI: 10.1021/acs.jproteome.2c00307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Protein database search engines are an integral component of mass spectrometry-based peptidomic analyses. Given the unique computational challenges of peptidomics, many factors must be taken into consideration when optimizing search engine selection, as each platform has different algorithms by which tandem mass spectra are scored for subsequent peptide identifications. In this study, four different database search engines, PEAKS, MS-GF+, OMSSA, and X! Tandem, were compared with Aplysia californica and Rattus norvegicus peptidomics data sets, and various metrics were assessed such as the number of unique peptide and neuropeptide identifications, and peptide length distributions. Given the tested conditions, PEAKS was found to have the highest number of peptide and neuropeptide identifications out of the four search engines in both data sets. Furthermore, principal component analysis and multivariate logistic regression were employed to determine whether specific spectral features contribute to false C-terminal amidation assignments by each search engine. From this analysis, it was found that the primary features influencing incorrect peptide assignments were the precursor and fragment ion m/z errors. Finally, an assessment employing a mixed species protein database was performed to evaluate search engine precision and sensitivity when searched against an enlarged search space containing human proteins.
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Affiliation(s)
- Eduardo A. De La Toba
- Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign, 61801
- Department of Chemistry, University of Illinois at Urbana-Champaign, 61801
| | - Krishna D. B. Anapindi
- Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign, 61801
- Department of Chemistry, University of Illinois at Urbana-Champaign, 61801
| | - Jonathan V. Sweedler
- Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign, 61801
- Department of Chemistry, University of Illinois at Urbana-Champaign, 61801
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Margolis EB, Moulton MG, Lambeth PS, O'Meara MJ. The life and times of endogenous opioid peptides: Updated understanding of synthesis, spatiotemporal dynamics, and the clinical impact in alcohol use disorder. Neuropharmacology 2023; 225:109376. [PMID: 36516892 PMCID: PMC10548835 DOI: 10.1016/j.neuropharm.2022.109376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 12/03/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022]
Abstract
The opioid G-protein coupled receptors (GPCRs) strongly modulate many of the central nervous system structures that contribute to neurological and psychiatric disorders including pain, major depressive disorder, and substance use disorders. To better treat these and related diseases, it is essential to understand the signaling of their endogenous ligands. In this review, we focus on what is known and unknown about the regulation of the over two dozen endogenous peptides with high affinity for one or more of the opioid receptors. We briefly describe which peptides are produced, with a particular focus on the recently proposed possible synthesis pathways for the endomorphins. Next, we describe examples of endogenous opioid peptide expression organization in several neural circuits and how they appear to be released from specific neural compartments that vary across brain regions. We discuss current knowledge regarding the strength of neural activity required to drive endogenous opioid peptide release, clues about how far peptides diffuse from release sites, and their extracellular lifetime after release. Finally, as a translational example, we discuss the mechanisms of action of naltrexone (NTX), which is used clinically to treat alcohol use disorder. NTX is a synthetic morphine analog that non-specifically antagonizes the action of most endogenous opioid peptides developed in the 1960s and FDA approved in the 1980s. We review recent studies clarifying the precise endogenous activity that NTX prevents. Together, the works described here highlight the challenges and opportunities the complex opioid system presents as a therapeutic target.
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Affiliation(s)
- Elyssa B Margolis
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA; Neuroscience Graduate Program, University of California, San Francisco, CA, USA.
| | - Madelyn G Moulton
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA
| | - Philip S Lambeth
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA
| | - Matthew J O'Meara
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA
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Mizuguchi T, Miyano K, Yamauchi R, Yoshida Y, Takahashi H, Yamazaki A, Ono H, Inagaki M, Nonaka M, Uezono Y, Fujii H. The first structure-activity relationship study of oxytocin as a positive allosteric modulator for the µ opioid receptor. Peptides 2023; 159:170901. [PMID: 36347314 DOI: 10.1016/j.peptides.2022.170901] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 11/02/2022] [Accepted: 11/03/2022] [Indexed: 11/07/2022]
Abstract
Positive allosteric modulators (PAMs) of G protein-coupled receptors (GPCRs) have drawn attention as novel drug candidates. PAMs can enhance the activities of endogenous agonists which are not only secreted at appropriate times and in parts of the body, but also are immediately metabolized. Therefore, they are expected to show fewer side effects than exogeneous orthosteric ligands. Recently, we have reported that oxytocin (OT) functioned as a PAM of the μ opioid receptor (MOR) which was one of the most potent targets for analgesics. OT is thus thought to be a useful compound for the development of novel analgesics. In this study, several OT analogs were synthesized and evaluated with an intact cell-based assay to investigate the crucial structures of OT for exerting the PAM activity. The assay results indicated that the cyclic structure formed by an intramolecular disulfide bond and the three C-terminal residues containing a small Gly residue of OT were essential for their function as a MOR-PAM. Intriguingly, two analogs having an amide or an ethylene tether instead of the intramolecular disulfide bridge did not have any PAM effects. The results suggested that the disulfide linkage of OT would be a key structure for exerting the PAM activity at the MOR.
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Affiliation(s)
- Takaaki Mizuguchi
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Kanako Miyano
- Department of Pain Control Research, The Jikei University School of Medicine, 3-25-8, Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan
| | - Risa Yamauchi
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Yuki Yoshida
- Laboratory of Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641, Yamazaki, Noda, Chiba 278-8510, Japan
| | - Hideki Takahashi
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Ami Yamazaki
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Haruka Ono
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Miku Inagaki
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Miki Nonaka
- Department of Pain Control Research, The Jikei University School of Medicine, 3-25-8, Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan
| | - Yasuhito Uezono
- Department of Pain Control Research, The Jikei University School of Medicine, 3-25-8, Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan.
| | - Hideaki Fujii
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan.
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Anapindi KDB, Romanova EV, Checco JW, Sweedler JV. Mass Spectrometry Approaches Empowering Neuropeptide Discovery and Therapeutics. Pharmacol Rev 2022; 74:662-679. [PMID: 35710134 DOI: 10.1124/pharmrev.121.000423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The discovery of insulin in the early 1900s ushered in the era of research related to peptides acting as hormones and neuromodulators, among other regulatory roles. These essential gene products are found in all organisms, from the most primitive to the most evolved, and carry important biologic information that coordinates complex physiology and behavior; their misregulation has been implicated in a variety of diseases. The evolutionary origins of at least 30 neuropeptide signaling systems have been traced to the common ancestor of protostomes and deuterostomes. With the use of relevant animal models and modern technologies, we can gain mechanistic insight into orthologous and paralogous endogenous peptides and translate that knowledge into medically relevant insights and new treatments. Groundbreaking advances in medicine and basic science influence how signaling peptides are defined today. The precise mechanistic pathways for over 100 endogenous peptides in mammals are now known and have laid the foundation for multiple drug development pipelines. Peptide biologics have become valuable drugs due to their unique specificity and biologic activity, lack of toxic metabolites, and minimal undesirable interactions. This review outlines modern technologies that enable neuropeptide discovery and characterization, and highlights lessons from nature made possible by neuropeptide research in relevant animal models that is being adopted by the pharmaceutical industry. We conclude with a brief overview of approaches/strategies for effective development of peptides as drugs. SIGNIFICANCE STATEMENT: Neuropeptides, an important class of cell-cell signaling molecules, are involved in maintaining a range of physiological functions. Since the discovery of insulin's activity, over 100 bioactive peptides and peptide analogs have been used as therapeutics. Because these are complex molecules not easily predicted from a genome and their activity can change with subtle chemical modifications, mass spectrometry (MS) has significantly empowered peptide discovery and characterization. This review highlights contributions of MS-based research towards the development of therapeutic peptides.
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Affiliation(s)
- Krishna D B Anapindi
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois (K.D.B.A., E.V.R., J.V.S.) and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska (J.W.C.)
| | - Elena V Romanova
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois (K.D.B.A., E.V.R., J.V.S.) and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska (J.W.C.)
| | - James W Checco
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois (K.D.B.A., E.V.R., J.V.S.) and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska (J.W.C.)
| | - Jonathan V Sweedler
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois (K.D.B.A., E.V.R., J.V.S.) and Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska (J.W.C.)
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