title: St. John's wort extract and hyperforin inhibit multiple phosphorylation steps of cytokine signaling and prevent inflammatory and apoptotic gene induction in pancreatic β cells.
abstract: The extract of the herbaceous plant St. John's wort (SJW) and its phloroglucinol component hyperforin (HPF) were previously shown to inhibit cytokine-induced STAT-1 and NF-κB activation and prevent damage in pancreatic β cells. To further clarify the mechanisms underlying their protective effects, we evaluated the phosphorylation state of various factors of cytokine signaling pathways and the expression of target genes involved in β-cell function, inflammatory response and apoptosis induction. In the INS-1E β-cell line, exposed to a cytokine mixture with/without SJW extract (2-5μg/ml) or HPF (1-5μM), protein phosphorylation was assessed by western blotting and expression of target genes by real-time quantitative PCR. SJW and HPF markedly inhibited, in a dose-dependent manner (from 60 to 100%), cytokine-induced activating phosphorylations of STAT-1, NF-κB p65 subunit and IKK (NF-κB inhibitory subunit IκBα kinase). MAPK and Akt pathways were also modulated by the vegetal compounds through hindrance of p38 MAPK, ERK1/2, JNK and Akt phosphorylations, each reduced by at least 65% up to 100% at the higher dose. Consistently, SJW and HPF a) abolished cytokine-induced mRNA expression of pro-inflammatory genes; b) avoided down-regulation of relevant β-cell functional/differentiation genes; c) corrected cytokine-driven imbalance between pro- and anti-apoptotic factors, by fully preventing up-regulation of pro-apoptotic genes and preserving expression or function of anti-apoptotic Bcl-2 family members; d) protected INS-1E cells against cytokine-induced apoptosis. In conclusion, SJW extract and HPF exert their protective effects through simultaneous inhibition of multiple phosphorylation steps along various cytokine signaling pathways and consequent restriction of inflammatory and apoptotic gene expression. Thus, they have a promising therapeutic potential for the prevention or limitation of immune-mediated β-cell dysfunction and damage leading to type 1 diabetes.
authors: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55 -Scuola Medica, Pisa, Italy. Electronic address: michela.novelli@med.unipi.it.
authors: Michela
authors: M
authors: Novelli
authors: Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, Strada Le Grazie 8, Verona, Italy. Electronic address: marta.menegazzi@univr.it.
authors: Marta
authors: M
authors: Menegazzi
authors: Institute of Clinical Physiology, CNR, Via Moruzzi 1, Pisa, Italy. Electronic address: pascale.beffy@ifc.cnr.it.
authors: Pascale
authors: P
authors: Beffy
authors: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55 -Scuola Medica, Pisa, Italy. Electronic address: svetlana.porozov@hotmail.com.
authors: Svetlana
authors: S
authors: Porozov
authors: Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, Strada Le Grazie 8, Verona, Italy. Electronic address: alex.gregorelli@gmail.com.
authors: Alex
authors: A
authors: Gregorelli
authors: Institute of Clinical Physiology, CNR, Via Moruzzi 1, Pisa, Italy. Electronic address: danielagiacopelli@hotmail.it.
authors: Daniela
authors: D
authors: Giacopelli
authors: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55 -Scuola Medica, Pisa, Italy. Electronic address: vincenzo.detata@med.unipi.it.
authors: Vincenzo
authors: V
authors: De Tata
authors: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via Roma 55 -Scuola Medica, Pisa, Italy. Electronic address: pellegrino.masiello@med.unipi.it.
authors: Pellegrino
authors: P
authors: Masiello
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D016207:Cytokines / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D020902:Hypericum / Q000737:chemistry*; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010696:Phloroglucinol / Q000031:analogs & derivatives* / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D050794:STAT1 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013729:Terpenes / Q000494:pharmacology*; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D016207:Cytokines; D016328:NF-kappa B; D010936:Plant Extracts; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; D013729:Terpenes; D004247:DNA; D010696:Phloroglucinol; D020928:Mitogen-Activated Protein Kinases; C001654:hyperforin
keywords: Cell death; Cytokines; Natural compounds; Pancreatic beta cells; Signaling pathways; Type 1 diabetes