New mimetic peptides of the kinase-inhibitory region (KIR) of SOCS1 through focused peptide libraries

Nunzianna Doti, Pasqualina L. Scognamiglio, Stefania Madonna, Claudia Scarponi, Menotti Ruvo, Giuseppe Perretta, Cristina Albanesi, Daniela Marasco

Research output: Contribution to journalArticle

Abstract

SOCS (suppressor of cytokine signalling) proteins are negative-feedback regulators of the JAK (Janus kinase)/STAT (signal transducer and activator of transcription) pathway. Their expression levels are low under physiological conditions, but they are up-regulated in response to cytokine stimulation in many immune and inflammatory processes. Overexpression of SOCS1 in keratinocyte clones abrogates the IFNγ (interferon γ)-induced expression of many pro-inflammatory genes and the release of related chemokines by blocking the JAK/STAT pathway. SOCS1 inhibits JAK2 kinase activity by binding the catalytic site of JAK2, with its KIR (kinase-inhibitory region) acting as a pseudo-substrate of the enzyme. In the present study, we screened a focused combinatorial peptide library of KIR to identify new peptides able to mimic its function with an improved affinity towards the JAK2catalytic site.Using an alanine-scanning method, KIR residues that are crucial for the interaction with JAK2 were unveiled. In this way, the KIR sequence was restricted to a shorter segment and 'non-essential' residues were replaced by different amino acids following a simplified combinatorial approach. We selected a new unnatural sequence able to bind to JAK2 with K d values in the nanomolar range. This peptide was tested in human keratinocyte cultures and reduced the phosphorylation of STAT1 and the expression levels of IRF-1 (interferon regulatory factor-1).

Original languageEnglish
Pages (from-to)231-240
Number of pages10
JournalBiochemical Journal
Volume443
Issue number1
DOIs
Publication statusPublished - Apr 1 2012

Keywords

  • Janus kinase/signal transducer and activator of transcription pathway (JAK/STAT pathway)
  • Kinase inhibitory region (KIR)
  • Mimetic peptide
  • Peptide library
  • Suppressor of cytokine signalling 1 (SOCS1)

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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