A peptide from Porphyra yezoensis stimulates the proliferation of IEC-6 cells by activating the insulin-like growth factor I receptor signaling pathway

Antimicrobial Peptides from Photosynthetic Marine Organisms with Potential Application in Aquaculture

Aquaculture production is at a record level and is estimated to increase in the coming years. However, this production can be negatively affected by infectious diseases produced by viruses, bacteria, and parasites, causing fish mortality and economic losses. Antimicrobial peptides (AMPs) are small peptides that may be promising candidates to replace antibiotics because they are the first line of defense in animals against a wide variety of pathogens and have no negative effects; they also show additional activities such as antioxidant or immunoregulatory functions, which makes them powerful alternatives for use in aquaculture. Moreover, AMPs are highly available in natural sources and have already been used in the livestock farming and food industries. Photosynthetic marine organisms can survive under all kinds of environmental conditions and under extremely competitive environments thanks to their flexible metabolism. For this reason, these organisms represent a powerful source of bioactive molecules as nutraceuticals and pharmaceuticals, including AMPs. Therefore, in this study we reviewed the present knowledge about AMPs from photosynthetic marine organism sources and analyzed whether they could be suitable for use in aquaculture.

Anti-Inflammatory Effects of Marine Bioactive Compounds and Their Potential as Functional Food Ingredients in the Prevention and Treatment of Neuroinflammatory Disorders

Functional foods include enhanced, enriched, fortified, or whole foods that impart health benefits beyond their nutritional value, particularly when consumed as part of a varied diet on a regular basis at effective levels. Marine sources can serve as the sources of various healthy foods and numerous functional food ingredients with biological effects can be derived from these sources. Microalgae, macroalgae, crustaceans, fungi, bacteria fish, and fish by-products are the most common marine sources that can provide many potential functional food ingredients including phenolic compounds, proteins and peptides, and polysaccharides. Neuroinflammation is closely linked with the initiation and progression of various neurodegenerative diseases, including Alzheimer's disease, Huntington's disease, and Parkinson's disease. Activation of astrocytes and microglia is a defense mechanism of the brain to counter damaged tissues and detrimental pathogens, wherein their chronic activation triggers neuroinflammation that can further exacerbate or induce neurodegeneration. Currently, available therapeutic agents only provide symptomatic relief from these disorders and no therapies are available to stop or slow down the advancement of neurodegeneration. Thereffore, natural compounds that can exert a protective effect against these disorders have therapeutic potential. Numerous chemical compounds, including bioactive peptides, fatty acids, pigments, alkaloids, and polysaccharides, have already been isolated from marine sources that show anti-inflammatory properties, which can be effective in the treatment and prevention of neuroinflammatory disorders. The anti-inflammatory potential of marine-derived compounds as functional food ingredients in the prevention and treatment of neurological disorders is covered in this review.

Seaweed-Derived Proteins and Peptides: Promising Marine Bioactives

Seaweeds are a typical food of East-Asian cuisine, to which are alleged several beneficial health effects have been attributed. Their availability and their nutritional and chemical composition have favored the increase in its consumption worldwide, as well as a focus of research due to their bioactive properties. In this regard, seaweed proteins are nutritionally valuable and comprise several specific enzymes, glycoproteins, cell wall-attached proteins, red algae phycobiliproteins, lectins, peptides, or mycosporine-like amino acids. This great extent of molecules has been reported to exert significant antioxidant, antimicrobial, anti-inflammatory, antihypertensive, antidiabetic, or antitumoral properties. Hence, knowledge on algae proteins and derived compounds have gained special interest for the potential nutraceutical, cosmetic or pharmaceutical industries based on these bioactivities. Although several molecular mechanisms of action on how these proteins and peptides exert biological activities have been described, many gaps in knowledge still need to be filled. Updating the current knowledge related to seaweed proteins and peptides is of interest to further asses their potential health benefits. This review addresses the characteristics of seaweed protein and protein-derived molecules, their natural occurrence, their studied bioactive properties, and their described potential mechanisms of action.

Seaweed Components as Potential Modulators of the Gut Microbiota

Macroalgae, or seaweeds, are a rich source of components which may exert beneficial effects on the mammalian gut microbiota through the enhancement of bacterial diversity and abundance. An imbalance of gut bacteria has been linked to the development of disorders such as inflammatory bowel disease, immunodeficiency, hypertension, type-2-diabetes, obesity, and cancer. This review outlines current knowledge from in vitro and in vivo studies concerning the potential therapeutic application of seaweed-derived polysaccharides, polyphenols and peptides to modulate the gut microbiota through diet. Polysaccharides such as fucoidan, laminarin, alginate, ulvan and porphyran are unique to seaweeds. Several studies have shown their potential to act as prebiotics and to positively modulate the gut microbiota. Prebiotics enhance bacterial populations and often their production of short chain fatty acids, which are the energy source for gastrointestinal epithelial cells, provide protection against pathogens, influence immunomodulation, and induce apoptosis of colon cancer cells. The oral bioaccessibility and bioavailability of seaweed components is also discussed, including the advantages and limitations of static and dynamic in vitro gastrointestinal models versus ex vivo and in vivo methods. Seaweed bioactives show potential for use in prevention and, in some instances, treatment of human disease. However, it is also necessary to confirm these potential, therapeutic effects in large-scale clinical trials. Where possible, we have cited information concerning these trials.

Acute glucose fluctuation promotes in vitro intestinal epithelial cell apoptosis and inflammation via the NOX4/ROS/JAK/STAT3 signaling pathway

High blood glucose commonly occurs in patients with diabetes mellitus, but little is known of its effects on intestinal epithelial cells, or its associated mechanisms of action therein. In the present study, intestinal epithelial cells were assigned to five groups: i) The normal glucose (NG) group, incubated in 5.0 mmol/l glucose; ii) the constant high glucose (CHG) group, treated with 25.0 mmol/l glucose; iii) the intermittent high glucose (IHG) group, treated with alternating doses of 5.0 and 25.0 mmol/l glucose every 8 h; iv) the mannose group, cultured in 25.0 mmol/l mannose (the osmotic control); and v) the IHG glucose + GKT137831 group, pretreated with 100 nmol/l NADPH oxidase 4 (NOX4) inhibitor, GKT137831, and then exposed to IHG. TNF-α, IL-1 and IL-6 levels were quantified using ELISA kits. Intestinal epithelial cell apoptosis was assessed by flow cytometry and oxidative stress was evaluated by reactive oxygen species (ROS) and malondialdehyde (MDA) detection. The expression levels of proteins associated with apoptosis and involved in the signal transduction of Janus kinase (JAK)/STAT3 pathway were assessed using western blot analysis. The results indicated that NOX4 expression was significantly higher in the CHG group than in the NG group (P<0.01), but lower than in the IHG group (P<0.001). The IHG group exhibited apoptosis and oxidative stress accompanied by the most significant increase in MDA, ROS and inflammatory cytokine levels (P<0.001), which was followed by that of the CHG group. Additionally, the IHG group exhibited reduced Bcl-2, as well as enhanced Bax and cleaved caspase-3 levels compared with the CHG group (P<0.001). Furthermore, the level of phosphorylated (p-)JAK/p-STAT3 was increased to a greater extent in the IHG group than in the CHG group (P<0.001). In conclusion, the findings of the present study indicated that CHG may trigger intestinal epithelial cell apoptosis and inflammation through the NOX4/ROS/JAK/STAT3 pathway, which may be aggravated by acute glucose fluctuation.

Peptidomics Analysis Discloses That Novel Bioactive Peptides Participate in Necrotizing Enterocolitis in a Rat Model

Necrotizing enterocolitis (NEC) is a common devastating gastrointestinal disease in premature infants, the molecular mechanisms of which have not been fully elucidated. Recently, endogenous peptides have garnered much attention owing to their role in diagnosis and treatment. However, changes in the peptide expression of NEC intestinal tissues remain poorly understood. In the present study, a comparative peptidomics profiling analysis was performed between NEC and control intestinal tissues via liquid chromatography-tandem mass spectrometry (LC-MS). In total, 103 upregulated and 73 downregulated peptides were identified in the intestinal tissues (fold change ≥ 1.5, p < 0.05). Bioinformatics analysis revealed that these differentially expressed peptides were significantly associated with NEC pathophysiology, including apoptosis, the TGF-β signaling pathway, the Wnt signaling pathway, and the MAPK signaling pathway. Furthermore, two putative peptides could inhibit apoptosis and promote the migration of intestinal epithelial cells induced by lipopolysaccharide; these peptides were derived from the protein domains MT1 and EZRI, respectively. In conclusion, our study revealed that endogenous peptides are involved in the pathophysiologic mechanism of NEC; nevertheless, further exploration is required in this regard.

Effect of the Plastein Reaction in Presence of Extrinsic Amino Acids on the Protective Activity of Casein Hydrolysate against Ethanol-Induced Damage in HHL-5 Cells

Casein hydrolysates (CH) were prepared using papain and modified by the plastein reaction (CH-P) in the presence of extrinsic phenylalanine (CH-P-Phe) or tryptophan (CH-P-Trp). The in vitro protective activity of CH and its modified products against ethanol-induced damage in HHL-5 cells was investigated. The results showed that the modification by the plastein reaction reduced the amino group content of CH. However, the modification by the plastein reaction in the presence of extrinsic amino acids could enhance the antioxidant, proliferative, cell cycle arresting, and anti-apoptosis activity of CH. Biological activities of CH and its modified products in the HHL-5 cells varied depending on the hydrolysate concentration (1, 2, and 3 mg/mL) and treatment time (24, 48, and 72 h). Generally, higher biological activities were found after cell treatment with CH or its modified products at concentration of 2 mg/mL for 48 h compared to other treatments. In addition, CH modified in the presence of tryptophan (CH-P-Trp) showed higher biological activity than that modified in the presence of phenylalanine (CH-P-Phe). Based on the obtained results, it can be concluded that casein hydrolysates with enhanced biological activity and potential health benefits can be produced by papain and the plastein reaction with the incorporation of extrinsic amino acids.

Pyropia yezoensis Protein Supplementation Prevents Dexamethasone-Induced Muscle Atrophy in C57BL/6 Mice

We investigated the protective effects of Pyropia yezoensis crude protein (PYCP) against dexamethasone (DEX)-induced myotube atrophy and its underlying mechanisms. DEX (3 mg/kg body weight, intraperitoneal injection) and PYCP (150 and 300 mg/kg body weight, oral) were administrated to mice for 18 days, and the effects of PYCP on DEX-induced muscle atrophy were evaluated. Body weight, calf thickness, and gastrocnemius and tibialis anterior muscle weight were significantly decreased by DEX administration (p < 0.05), while PYCP supplementation effectively prevented the DEX-induced decrease in body weight, calf thickness, and muscle weight. PYCP supplementation also attenuated the DEX-induced increase in serum glucose, creatine kinase, and lactate dehydrogenase levels. Additionally, PYCP supplementation reversed DEX-induced muscle atrophy via the regulation of the insulin-like growth factor-I/protein kinase B/rapamycin-sensitive mTOR complex I/forkhead box O signaling pathway. The mechanistic investigation revealed that PYCP inhibited the ubiquitin-proteasome and autophagy-lysosome pathways in DEX-administrated C57BL/6 mice. These findings demonstrated that PYCP increased protein synthesis and decreased protein breakdown to prevent muscle atrophy. Therefore, PYCP supplementation appears to be useful for preventing muscle atrophy.

Phycoerythrin-Derived Tryptic Peptide of a Red Alga Pyropia yezoensis Attenuates Glutamate-Induced ER Stress and Neuronal Senescence in Primary Rat Hippocampal Neurons

SCOPE

Glutamate excitotoxicity has been observed in association with neurodegenerative disorders. This study aimed to investigate whether a phycoerythrin-derived tryptic peptide of Pyropia yezoensis (PYP) reduces glutamate-induced excitotoxicity and neuronal senescence in primary rat hippocampal neurons.

METHODS AND RESULTS

Glutamate exposure (100 μm) decreased cell viability and increased expression of endoplasmic reticulum (ER) stress response protein glucose-regulated protein 78 (GRP78) starting at 60 min following glutamate exposure, which was prevented by pretreating the neurons with PYP (1 μg mL^-1 ). The glutamate-induced increase in GRP78 expression was downregulated by blocking N-methyl-d-aspartate (NMDA) receptor with MK801 (10 μm) and inhibiting c-Jun N-terminal kinase (JNK) phosphorylation with SP600125 (10 μm). Moreover, phosphorylation of JNK was decreased by blockade of NMDA receptor. The PYP pretreatment downregulated glutamate-induced increase in GRP78 expression and JNK phosphorylation, and this effect was abolished by inhibiting tropomyosin-related kinase B (TrkB) receptor, phosphatidylinositiol 3-kinase, and extracellular signal-regulated kinase (ERK)1/2 using cyclotraxin B (200 nm), LY294002 (20 μm), and SL327 (10 μm), respectively. In addition, PYP downregulated increase in GRP78 expression, senescence-associated β-galactosidase activity, and neurite degeneration in aging hippocampal neurons.

CONCLUSION

These findings indicate that activation of TrkB receptor-mediated ERK1/2 by PYP attenuates glutamate-induced ER stress, which may improve the survival of hippocampal neurons with age.

Phycoerythrin Peptide from Pyropia yezoensis Alleviates Endoplasmic Reticulum Stress Caused by Perfluorooctane Sulfonate-Induced Calcium Dysregulation

Perfluorooctane sulfonate (PFOS), a stable fluorosurfactant, causes endoplasmic reticulum (ER) stress in the brain. This study was designed to investigate whether a phycoerythrin-derived peptide of Pyropia yezoensis (PYP) reduces PFOS-induced ER stress associated with calcium dysregulation. The protective effects of PYP were determined by cell viability, immunoblotting for ER stress response protein glucose-regulated protein 78 (GRP78) and calcium-dependent protein kinases in rat frontal cortical neurons. PFOS-induced decrease in cell viability was attenuated by PYP pretreatment (1 µg/mL) for 24 h, which was downregulated by inhibiting tropomyosin-receptor kinase B (TrkB). PYP pretreatment downregulated the increase in intracellular calcium levels and phosphorylation of calcium/calmodulin-dependent protein kinase II and c-Jun N-terminal kinase which are associated with a PFOS-induced increase in GRP78. The PFOS-induced increase in GRP78 was downregulated via activation of TrkB receptor-linked extracellular signal-regulated kinases 1/2 (ERK1/2) by PYP pretreatment. Moreover, PYP microinjections (1 µg/kg, 0.54 nmol) attenuated the GRP78 expression in rat prefrontal cortex caused by PFOS (10 mg/kg) exposure for 2 weeks. These findings demonstrate that PYP enhances frontal cortical neuron viability via activation of TrkB receptor-ERK1/2 signaling and attenuation of ER stress in rat prefrontal cortex against PFOS exposure, suggesting that PYP might prevent neuronal dysfunctions caused by PFOS-induced ER stress.

Bioactive Compounds of Edible Purple Laver Porphyra sp. (Nori)

Porphyra sp. (nori) is widely cultivated as an important marine crop. Dried nori contains numerous nutrients, including vitamin B₁₂, which is the only vitamin absent from plant-derived food sources. Vegetarian diets are low in iron and vitamin B₁₂; depletion of both causes severe anemia. Nori also contains large amounts of iron compared with other plant-derived foods and eicosapentaenoic acid, which is an important fatty acid found in fish oils. In nori, there are also many bioactive compounds that exhibit various pharmacological activities, such as immunomodulation, anticancer, antihyperlipidemic, and antioxidative activities, indicating that consumption of nori is beneficial to human health. However, Porphyra sp. contains toxic metals (arsenic and cadmiun) and/or amphipod allergens, the levels of which vary significantly among nori products. Further evidence from human studies of such beneficial or adverse effects of nori consumption is required.

Protein extracted from Porphyra yezoensis prevents cisplatin-induced nephrotoxicity by downregulating the MAPK and NF-κB pathways

Acute renal failure is a serious complication of treatment with the anticancer drug cisplatin. Cisplatin exerts a cytotoxic effect on renal cells by inducing apoptosis through activating the tumor suppressor p53, nuclear factor‑κB (NF‑κB) and mitogen‑activated protein kinase (MAPK)/p38 pathways. Effects of protein extracts of the brown seaweed Porphyra yezoensis (P. yezoensis) on cytotoxicity, inflammation and cell proliferation have been reported; however, the effects of P. yezoensis protein (PYP) extract on cisplatin‑induced renal injury have remained elusive. The present study investigated the effects of PYP on cisplatin‑induced nephrotoxicity in the HK2 human proximal tubular epithelial cell line. PYP treatment reduced cisplatin‑induced apoptosis and death of HK2 cells by restoring the B‑cell lymphoma‑2 (Bcl‑2)‑associated X protein (Bax)/Bcl‑2 imbalance, cytochrome c release and caspase‑3 activation. In addition, PYP activated the redox‑sensitive transcription factor NF‑κB via stimulating the nuclear translocation of p65 in HK2 cells. PYP also restored renal antioxidant levels and increased the total and nuclear accumulation of NF erythroid 2‑related factor 2 in HK2 cells. PYP markedly attenuated cisplatin‑induced p38, MAPK and c‑Jun N‑terminal kinase phosphorylation. Furthermore, treatment with PYP ameliorated cisplatin‑induced renal cell damage by upregulating antioxidant defense mechanisms and downregulating the MAPK and NF‑κB signaling pathways. In addition, mice were divided into three treatment groups (control, cisplatin and PYP + cisplatin) and the effects of PYP were evaluated in a mouse model of cisplatin‑induced acute kidney injury. The concentrations of blood urea nitrogen and serum creatinine in the PYP + cisplatin group were lower than those in the cisplatin group. The mRNA expression levels of inflammatory factors interleukin‑6 (IL‑6), IL‑1β, tumor necrosis factor‑α and monocyte chemoattractant protein‑1 in the kidney tissues of the PYP + cisplatin group were also lower than those in the cisplatin group. These results suggest that PYP treatment had a preventive effect on nephrotoxicity, specifically by downregulating the MAPK and NF‑κB signaling pathways and the mRNA levels of inflammatory genes.

Phosphatidylserine enhances IKBKAP transcription by activating the MAPK/ERK signaling pathway

Familial dysautonomia (FD) is a genetic disorder manifested due to abnormal development and progressive degeneration of the sensory and autonomic nervous system. FD is caused by a point mutation in the IKBKAP gene encoding the IKAP protein, resulting in decreased protein levels. A promising potential treatment for FD is phosphatidylserine (PS); however, the manner by which PS elevates IKAP levels has yet to be identified. Analysis of ChIP-seq results of the IKBKAP promoter region revealed binding of the transcription factors CREB and ELK1, which are regulated by the mitogen-activated protein kinase (MAPK)/extracellular-regulated kinase (ERK) signaling pathway. We show that PS treatment enhanced ERK phosphorylation in cells derived from FD patients. ERK activation resulted in elevated IKBKAP transcription and IKAP protein levels, whereas pretreatment with the MAPK inhibitor U0126 blocked elevation of the IKAP protein level. Overexpression of either ELK1 or CREB activated the IKBKAP promoter, whereas downregulation of these transcription factors resulted in a decrease of the IKAP protein. Additionally, we show that PS improves cell migration, known to be enhanced by MAPK/ERK activation and abrogated in FD cells. In conclusion, our results demonstrate that PS activates the MAPK/ERK signaling pathway, resulting in activation of transcription factors that bind the promoter region of IKBKAP and thus enhancing its transcription. Therefore, compounds that activate the MAPK/ERK signaling pathway could constitute potential treatments for FD.

Bioactive peptide from Pyropia yezoensis and its anti-inflammatory activities

Pyropia yezoensis (P. yezoensis) is an important marine algae. Its high protein content serves as a good source of biologically active peptides. Potent inhibitory effects on the production of inflammatory mediators were observed in a bioactive peptide derived from P. yezoensis (peptide from P. yezoensis; PPY1), as demonstrated in lipopolysaccharide (LPS)-stimulated macrophages. The present study showed that peptide concentrations ranging from 250 to 1,000 ng/ml had no significant cytotoxicity in the cell viability assay when applied to the RAW 264.7 cells for 24 h. PPY1 completely inhibited LPS‑stimulated nitric oxide (NO) release in a dose-dependent manner. Fluorescence intensity, corresponding to intracellular reactive oxygen species (ROS) produced by 10 ng/ml LPS-stimulated cells, significantly shifted, indicating that the peptide reduced the level of ROS. Furthermore, PPY1 exerted potent inhibitory activity to reduce the release of pro-inflammatory cytokines (inducible NO synthase, cyclooxygenase-2, interleukin-1β and tumor necrosis factor-α) in LPS-stimulated macrophages in a dose-dependent manner. These results also showed that the anti-inflammatory activity of PPY1 was associated with downregulation of extracellular signal-regulated kinase, protein 38, and c-jun NH2-terminal kinase phosphorylation in the mitogen-activated protein kinase pathways. In conclusion, PPY1 can have a significant role as an anti-inflammatory agent, with a potential for use in marine products.

Proteins and Carbohydrates from Red Seaweeds: Evidence for Beneficial Effects on Gut Function and Microbiota

Based on their composition, marine algae, and namely red seaweeds, are good potential functional foods. Intestinal mucosal barrier function refers to the capacity of the intestine to provide adequate containment of luminal microorganisms and molecules. Here, we will first outline the component of seaweeds and will summarize the effects of these on the regulation of mucosal barrier function. Special attention will be paid to unique components of red seaweeds: proteins and derived peptides (e.g., phycobiliproteins, glycoproteins that contain “cellulose binding domains”, phycolectins and the related mycosporine-like amino acids) together with polysaccharides (e.g., floridean starch and sulfated galactans, such as carrageenans, agarans and “dl-hybrid”) and minerals. These compounds have been shown to exert prebiotic effects, to regulate intestinal epithelial cell, macrophage and lymphocyte proliferation and differentiation and to modulate the immune response. Molecular mechanisms of action of peptides and polysaccharides are starting to be elucidated, and evidence indicating the involvement of epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGFR), Toll-like receptors (TLR) and signal transduction pathways mediated by protein kinase B (PKB or AKT), nuclear factor-κB (NF-κB) and mitogen activated protein kinases (MAPK) will also be summarized. The need for further research is clear, but in vivo experiments point to an overall antiinflammatory effect of these algae, indicating that they can reinforce membrane barrier function.

Chemoprotective effects of a recombinant protein from Pyropia yezoensis and synthetic peptide against acetaminophen-induced Chang liver cell death

In the present study, the chemoprotective effects of recombinant Pyropia yezoensis (P. yezoensis) protein 1 (PYP1) were examined in acetaminophen (APAP)-treated Chang liver cells. The analysis of P. yezoensis revealed the presence of both mature and immature variants of PYP1. PYP1s, designated as PYP1 (15 kDa), PYP1-AC (12 kDa) and PYP1-B (5 kDa), were successfully expressed in Escherichia coli, and their chemoprotective effects were then examined. In addition, a peptide of 11 residues (ALEGGKSSGGG), which is a common sequence at the N-terminus all of the PYP1s, was synthesized and examined. The effects of treatment with PYP1s and the synthetic peptide (SP) on cell proliferation were determined by MTS assay. Our results clearly demonstrated that treatment with all the PYP1s and SP significantly promoted the proliferation of Chang liver cells, protecting them against APAP. Thus, we concluded that recombinant PYP1s exert protective effects against injury to Chang liver cells.

The proliferative effects of Pyropia yezoensis peptide on IEC-6 cells are mediated through the epidermal growth factor receptor signaling pathway

For a number of years, seaweed has been used as a functional food in Asian countries, particularly in Korea, Japan and China. Pyropia yezoensis is a marine red alga that has potentially beneficial biological activities. In this study, we examined the mechanisms through which a Pyropia yezoensis peptide [PYP1 (1–20)] induces the proliferation of IEC-6 cells, a rat intestinal epithelial cell line, and the involvement of the epidermal growth factor receptor (EGFR) signaling pathway. First, cell viability assay revealed that PYP1 (1–20) induced cell proliferation in a concentration-dependent manner. Subsequently, we examined the mechanisms responsible for this induction of proliferation induced by PYP1 (1–20). EGFR is widely expressed in mammalian epithelial tissues, and the binding of this ligand affects a variety of cell physiological parameters, such as cell growth and proliferation. PYP1 (1–20) increased the expression of EGFR, Shc, growth factor receptor-bound protein 2 (Grb2) and son of sevenless (SOS). EGFR also induced the activation of the Ras signaling pathway through Raf, MEK and extracellular signal-regulated kinase (ERK) phosphorylation. In addition, cell cycle analysis revealed the expression of cell cycle-related proteins. The results demonstrated an increased number of cells in the G1 phase and an enhanced cell proliferation. In addition, the upregulation of cyclin D, cyclin E, Cdk2, Cdk4 and Cdk6 was observed accompanied by a decreased in p21 and p27 expression. These findings suggest that PYP1 (1–20) stimulates the proliferation of rat IEC-6 cells by activating the EGFR signaling pathway. Therefore, PYP1 (1–20) may be a potential source for the development of bio-functional foods which promotes the proliferation of intestinal epithelial cells.