Characterization of a Protein‐Protein Interaction Between NIL‐16 and HDAC3

Abstract

Neuronal Interleukin‐16 (NIL‐16) is the neuronal‐specific splice isoform of the interleukin‐16 (IL16) gene. NIL‐16 shows restricted expression to the hippocampus and cerebellum: brain regions involved in learning and memory. NIL‐16 shares an identical C‐terminal protein‐coding sequence with pro‐IL‐16; the shorter, immune‐specific splice isoform that is the pro‐inflammatory precursor to the cytokine IL‐16. The mutual amino acid sequence between pro‐IL‐16 and NIL‐16 contains three PDZ protein interaction domains (PDZ‐1, PDZ‐2 and PDZ‐2). In addition to serving as the precursor to IL‐16, pro‐IL‐16 regulates immune cell proliferation through a PDZ‐2 mediated‐interaction with the nuclear‐associated protein HDAC3. Emerging evidence indicates that HDAC3 plays a critical role in regulating fundamental mechanisms involved in brain development and mechanisms of learning and memory. Here, we hypothesize that like pro‐IL‐16, a similar protein‐protein interaction exists between NIL‐16 and HDAC3 suggesting a possible role in mediating important processes in neurons. To test this hypothesis, we conducted pulldown assays with mouse cerebellar brain extract using fusion proteins coding for the PDZ‐2 domain of NIL‐16 and the PDZ‐interacting motif of HDAC3. Our results indicate that we can affinity purify HDAC3 from cerebellar extract with the PDZ‐2 domain of NIL‐16. Likewise, we also affinity purified NIL‐16 with the PDZ‐interacting motif of HDAC3. Additionally, using immunofluorescent microscopy, we show overlapping distribution of NIL‐16 and HDAC3 expressed in COS‐7 cells and in cultured cerebellar granule neurons. Finally, we performed co‐immunoprecipitation assays with cerebellar extract demonstrating preliminary evidence that NIL‐16 and HDAC3 form an in vivo protein complex in neurons.Support or Funding InformationResearch in this study was funded by NIH‐Maximizing Access to Research Careers Undergraduate Student Training in Academic Research (MARC U*STAR) award number T34GM092711, start‐up funds provided to Dr. Steven Fenster (Fort Lewis College), and funds received from SSNAP (Science Scholars the Native American Path) by SACNAS (Dr. Les Sommerville, Fort Lewis College).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.