Neo-kyotorphin (Thr-Ser-Lys-Tyr-Arg), a new analgesic peptide

The Therapeutic Potential of Intra-Articular Injection of Synthetic Deer Antler Peptides in a Rat Model of Knee Osteoarthritis

Synthetic deer antler peptides (TSKYR, TSK, and YR) stimulate the proliferation of human chondrocytes and osteoblasts and increase the chondrocyte content of collagen and glycosamino-glycan in vitro. This study investigated the peptide mixture's pain relief and chondroprotective effect in a rat model of collagenase-induced osteoarthritis. Thirty-six adult male Sprague-Dawley rats were divided into three groups: control (saline), positive control (hyaluronic acid), and ex-perimental (peptides). Intra-articular collagenase injections were administered on days 1 and 4 to induce osteoarthritis in the left knees of the rats. Two injections of saline, hyaluronic acid, or the peptides were injected into the same knees of each corresponding group at the beginning of week one and two, respectively. Joint swelling, arthritic pain, and histopathological changes were evaluated. Injection of the peptides significantly reduced arthritic pain compared to the control group, as evidenced by the closer-to-normal weight-bearing and paw withdrawal threshold test results. Histological analyses showed reduced cartilage matrix loss and improved total cartilage degeneration score in the experimental versus the control group. Our findings suggest that intra-articular injection of synthetic deer antler peptides is a promising treatment for osteoarthritis.

Biological Activities of Deer Antler-Derived Peptides on Human Chondrocyte and Bone Metabolism

Orally administered "tortoiseshell and deer antler gelatin" is a common traditional medicine for patients with osteoporosis or osteoarthritis. From the pepsin-digested gelatin, we previously isolated and identified the osteoblast-stimulating pentapeptide, TSKYR. Its trypsin digestion products include the dipeptide YR, enhancing calcium ion uptake, and tripeptide TSK, resulting in remarkable 30- and 50-fold increases in mineralized nodule area and density in human osteoblast cells. These peptides were chemically synthesized in this study. The composition of deer antler preparations comprises not only proteins and peptides but also a significant quantity of metal ion salts. By analyzing osteoblast growth in the presence of peptide YR and various metal ions, we observed a synergistic effect of calcium and strontium on the effects of YR. Those peptides could also stimulate the growth of C2C12 skeletal muscle cells and human chondrocytes, increasing collagen and glycosaminoglycan content in a three-dimensional environment. The maintenance of bone homeostasis relies on a balance between osteoclasts and osteoblasts. Deer antler peptides were observed to inhibit osteoclast differentiation, as evidenced by ROS generation, tartrate-resistant acid phosphatase (TRACP) activity assays, and gene expression in RAW264.7 cells. In summary, our findings provide a deep understanding of the efficacy of this folk medicine.

Isolation, Identification, and Characterization of Bioactive Peptides in Human Bone Cells from Tortoiseshell and Deer Antler Gelatin

Tortoiseshell and deer antler gelatin has been used to treat bone diseases in Chinese society. A pepsin-digested gelatin peptide with osteoblast-proliferation-stimulating properties was identified via LC-MS/MS. The resulting pentapeptide, TSKYR, was presumably subjected to further degradation into TSKY, TSK, and YR fragments in the small intestine. The above four peptides were chemically synthesized. Treatment of tripeptide TSK can lead to a significant 30- and 50-fold increase in the mineralized nodule area and density in osteoblast cells and a 47.5% increase in the number of chondrocyte cells. The calcium content in tortoiseshell was relatively higher than in human soft tissue. The synergistic effects of calcium ions and the peptides were observed for changes in osteoblast proliferation and differentiation. Moreover, these peptides can enhance the expression of RUNX2, OCN, FGFR2, and FRFR3 genes in osteoblasts, and aggrecan and collagen type II in chondrocyte (patent pending).

PACAP and Other Neuropeptide Targets Link Chronic Migraine and Opioid-induced Hyperalgesia in Mouse Models

Chronic use of opioids can produce opioid-induced hyperalgesia (OIH), and when used to treat migraine, these drugs can result in increased pain and headache chronicity. We hypothesized that overlapping mechanisms between OIH and chronic migraine occur through neuropeptide dysregulation. Using label-free, non-biased liquid chromatography-mass spectrometry to identify and measure changes in more than 1500 neuropeptides under these two conditions, we observed only 16 neuropeptides that were altered between the two conditions. The known pro-migraine molecule, calcitonin-gene related peptide, was among seven peptides associated with chronic migraine, with several pain-processing neuropeptides among the nine other peptides affected in OIH. Further, composite peptide complements Pituitary adenylate cyclase-activating polypeptide (PACAP), Vasoactive intestinal peptide (VIP) and Secretogranin (SCG) showed significant changes in both chronic migraine and OIH. In a follow-up pharmacological study, we confirmed the role of PACAP in models of these two disorders, validating the effectiveness of our peptidomic approach, and identifying PACAP as a mechanistic link between chronic migraine and OIH. Data are available via ProteomeXchange with identifier PXD013362.

Hemoglobin-derived peptides as novel type of bioactive signaling molecules

Most bioactive peptides are generated by proteolytic cleavage of large precursor proteins followed by storage in secretory vesicles from where they are released upon cell stimulation. Examples of such bioactive peptides include peptide neurotransmitters, classical neuropeptides, and peptide hormones. In the last decade, it has become apparent that the breakdown of cytosolic proteins can generate peptides that have biological activity. A case in point and the focus of this review are hemoglobin-derived peptides. In vertebrates, hemoglobin (Hb) consists of a tetramer of two α- and two β-globin chains each containing a prosthetic heme group, and is primarily involved in oxygen delivery to tissues and in redox reactions (Schechter Blood 112:3927-3938, 2008). The presence of α- and/or β-globin chain in tissues besides red blood cells including rodent and human brain and peripheral tissues (Liu et al. Proc Natl Acad Sci USA 96:6643-6647, 1999; Newton et al. J Biol Chem 281:5668-5676, 2006; Wride et al. Mol Vis 9:360-396, 2003; Setton-Avruj Exp Neurol 203:568-578, 2007; Ohyagi et al. Brain Res 635:323-327, 1994; Schelshorn et al. J Cereb Blood Flow Metab 29:585-595, 2009; Richter et al. J Comp Neurol 515:538-547, 2009) suggests that globins and/or derived peptidic fragments might play additional physiological functions in different tissues. In support of this hypothesis, a number of Hb-derived peptides have been identified and shown to have diverse functions (Ivanov et al. Biopoly 43:171-188, 1997; Karelin et al. Neurochem Res 24:1117-1124, 1999). Modern mass spectrometric analyses have helped in the identification of additional Hb peptides (Newton et al. J Biol Chem 281:5668-5676, 2006; Setton-Avruj Exp Neurol 203:568-578, 2007; Gomes et al. FASEB J 23:3020-3029, 2009); the molecular targets for these are only recently beginning to be revealed. Here, we review the status of the Hb peptide field and highlight recent reports on the identification of a molecular target for a novel set of Hb peptides, hemopressins, and the implication of these peptides to normal cell function and disease. The potential therapeutic applications for these Hb-derived hemopressin peptides will also be discussed.

[Functional arginine-containing amino acid sequences in peptides and proteins]

L-arginine is a source of nitrogen oxide and plays a great role in a number of other biochemical processes. Functions and prospects for practical application of five groups of arginine-containing amino acid sequences and synthetic polyarginine sequences are considered. The physiological characteristics of well-known arginine-containing peptides, such as RGD peptides, kyotorphin, and tuftsin, are described in detail. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru

Lipidic membranes are potential "catalysts" in the ligand activity of the multifunctional pentapeptide neokyotorphin

Neokyotorphin (NKT) is a multifunctional pentapeptide that is involved in biological functions as diverse as analgesia, antihibernatic regulation and proliferation stimulus of tumour cells. The interaction of neokyotorphin with cell membranes is potentially important to all these multiple biological processes since receptor-mediated processes are thought to be involved in neokyotorphin action. Sargent and Schwyzer proposed in their "membrane catalysis" model that ligands interact with membrane lipids in order to adopt the necessary conformation for cell receptors. We have used fluorescence techniques to study the depth, orientation and extent of incorporation of NKT with model membrane systems (lipidic vesicles). The roles of lipid charge, membrane phase and sterol presence were investigated. The phenolic ring of tyrosine is located in a shallow position in membranes. The extent of partition is less in gel crystalline membranes than in liquid crystalline membranes. Addition of cholesterol causes a reorientation of the tyrosine ring at the interface of lipidic bilayers. Lipidic membranes meet all the conditions required for acting as potential "catalysts" in the ligand activity of the multifunctional pentapeptide NKT, because they modulate the exposure and orientation of the phenolic ring, which is most likely involved in docking to receptors.

Pancreastatin--a novel regulatory peptide?

Pancreastatin is a 49 amino acid peptide originally isolated from porcine pancreas on the basis of its C-terminal glycinamide as isolation criterion. It is derived by proteolytic processing from chromogranin A, an acidic protein component of secretory granules in endocrine and neuronal cells. The primary structures of human, porcine, bovine and rat pancreastatin have been determined on the protein or cDNA level and show 70% sequence homology. By immunocytochemistry, pancreastatin has been detected in the pituitary, adrenal gland, pancreas, CNS and throughout the gastrointestinal tract. In pancreatic islets, pancreastatin is co-localized with insulin, glucagon and somatostatin. The principle biological activities of this peptide are: inhibition of insulin release and of exocrine pancreatic secretion. These effects which can be assigned to the amidated C-terminal part of the molecule have been demonstrated in several species. Whether or not pancreastatin can be classified as a novel peptide hormone that under physiological conditions plays a role in the regulation of the endocrine and exocrine pancreas, is still a matter of controversy.

Recent developments in the chemistry of gastrointestinal peptides

Work carried out in different laboratories has shown that the peptide pattern of the intestinal tissue is very complex and that some of the peptides are identical to those found in the central nervous system. The best studied of the peptides are of a hormonal nature, but recently evidence has been obtained that others may primarily act as antibiotics. In addition, peptides have been isolated that are fragments of some well-known proteins that have not been viewed as being prohormones. Whether the latter peptides only represent transient degradation products of the proteins or whether, at least some of them, have a physiologically meaningful selective function of their own is not yet clear.

Effect of intracerebroventricular injection of neokyotorphin on the thermoregulatory responses in rats

Intracerebroventricular injection of neokyotorphin (NKT) (0.5-2.0 micrograms) caused a dose-related increase in body temperature (Tb) of rats maintained at 28 degrees C. The change in Tb of the rat induced by the optimal dose of NKT (1 microgram) was attenuated when the rat was exposed to 18 degrees C. At both ambient temperatures, heat production was not affected but heat loss was significantly reduced at 28 degrees C in rats receiving 1 microgram NKT. Pretreatment with naloxone (5 mg/kg, IP) significantly reduced the hyperthermic effect induced by NKT (1 microgram). These results suggest that NKT can affect the prevailing thermoregulatory heat loss activities and this effect may be mediated through stimulated release of endogenous opioids.

Circulation of a fragment of haemoglobin alpha-chain during a pentagastrin-induced flush in patients with metastatic carcinoid tumours

Intravenous injection of pentagastrin (0.6 microgram/kg body wt) into two patients with metastatic carcinoid tumours evoked a severe carcinoid flush. Analysis by reverse-phase HPLC of acetone-extracts of peripheral blood taken from the patients during the flush indicated the presence of a peptide identified as the residues (1-33) fragment of the alpha-chain of haemoglobin. The peptide was not detected in blood taken from the patients immediately before stimulation of the flush or in the blood of healthy subjects after pentagastrin injection. The observation is interpreted as evidence that the pentagastrin-induce carcinoid flush is associated with the activation and possible release of a tumour protease that result in damage to erythrocytes.

Use of a cDNA clone to identify a supposed precursor protein containing valosin

Valosin, a novel 25-amino-acid peptide isolated recently from pig intestine, has several effects on the digestive system of dogs. We report here that the valosin-specific complementary DNA clone from pigs codes for a polypeptide unlike most precursors of biologically active peptides. The predicted protein lacks a characteristic amino-terminal hydrophobic signal sequence and contains no processing signals of the type acted upon by endopeptidases to generate other active peptides from precursors. Antibodies to synthetic valosin have been used to show that nearly all valosin immunoreactivity is in the cytoplasm and that the protein detected (valosin-containing protein, VCP), although smaller than the predicted product of the cDNA sequence, is much larger than valosin. Valosin-specific messenger RNA is found in extracts from many pig tissues, which contrasts with the restricted occurrence expected of a biologically active peptide. We conclude that valosin is an artefact of the purification procedure and does not occur in vivo.

Valosin: isolation and characterization of a novel peptide from porcine intestine

The isolation and primary structure of a novel gastrointestinal peptide, designated valosin, is described. The peptide was purified from porcine upper gut extracts using an HPLC and N-terminal sequence screening strategy which depends on chromatographic and structural characteristics as isolation criterion. The amino acid sequence of this peptide consists of 25 amino acid residues:

A C-terminal fragment of hemoglobin beta-chains in extracts of porcine upper intestine

A 32-residue peptide has been isolated from extracts of porcine upper intestine. Amino acid sequence determination showed that the peptide is a fragment of hemoglobin, corresponding to the C-terminal part of the beta-chain. The region in the beta-chain which precedes the isolated fragment is hydrophobic (8 Leu/Val/Ile) and has no charges at 10 preceding positions. It therefore, to some extent, resembles the structure of 'signal sequences' which may suggest a specific cleavage site in hemoglobin beta-chains.