Invited Speaker ANZOS Annual Scientific Meeting 2021

Unravelling erusiolin function in health and disease (#15)

Michelle Cielesh 1 , Nektaria Pezos 2 , Sameer Kulkarni 3 , Richard Payne 3 , Herbert Herzog 4 , Dorit Samocha-Boet 4 , Richard L Young 2 , Samantha Hocking 5 , Mark Larance 1
  1. Charles Perkins Centre and School of Life and Environmental Sciences, University of Sydney, Camperdown, NSW, Australia
  2. South Australia Health and Medical Research Institute, University of Adelaide, Adelaide, SA, Australia
  3. School of Chemistry, University of Sydney, Sydney, NSW, Australia
  4. Garvan Institute of Medical Research, St Vincents Hospital, Darlinghurst, NSW, Australia
  5. Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia

Low-abundance small proteins in human plasma (e.g. insulin, GLP-1, chemokines) play key roles in maintaining metabolic homeostasis and are frequently disrupted in diverse disease states. Using our previously developed SPEA protocol (Harney et. al. 2019. Mol. Cell. Proteomics, 18(9):1899-1915), we can identify and quantify these active low abundance small-protein hormones in plasma. This has allowed us to explore all components in plasma, including potential novel protein factors, using unbiased mass spectrometry-based analysis. Using the SPEA protocol to analyse human plasma, allowed detection of three peptides from the uncharacterised 8 kDa protein. One of these was a highly conserved peptide (erusiolin) that was significantly increased in abundance 10-fold approximately 1-3 hours after a mixed meal test. Absolute quantification showed erusiolin peaked at ~100 nM in plasma after food. The mRNA encoding erusiolin is largely duodenum-specific and immunohistochemistry analysis of human small intestine using an erusiolin-specific antibody, demonstrated a staining pattern consistent with expression in enteroendocrine cells. Co-staining confirmed overlap in expression with previously known enteroendocrine markers and showed significant co-expression of erusiolin and gastric inhibitory polypeptide (GIP). Mouse systems genetics datasets suggested a link to brain transcriptional regulation by erusiolin in appetite regulatory centers. Intraperitoneal injection of erusiolin into mice just prior to the night feeding cycle significantly reduced overnight food intake and body weight compared to either vehicle, or truncated forms of erusiolin. Immunofluorescence analysis of brain neuron activation after erusioin intraperitoneal injection highlighted the area postrema as a key region that is activated. Current work focuses on the identification of the cognate receptor for erusiolin expressed in these neurons that likely mediate the observed changes in feeding behavior.