IMBICE   05372
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA CELULAR
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
CA512?RESP18HD and insulin interaction in the insulin secretory pathway
Autor/es:
ERMÁCORA, MARIO R.; LLOVERA, RAMIRO E.; MÜLLER ANDREAS; TOLEDO, PAMELA L.; SOLIMENA, MICHELE; TORKKO, JUHA M.
Lugar:
Dresde
Reunión:
Congreso; 2nd Joint meeting of the EASD - Islet Study Group and the Beta Cell Workshop; 2017
Resumen:
ICA512/IA?2/PTPRN is a decoy receptor protein tyrosine phosphatase enriched in secretory granules (SGs) of neuroendocrine cells. Previous studies imply its involvement in the biogenesis, trafficking and exocytosis of insulin SGs, as well as in β-cell proliferation. The function and structure of a large portion of its N-terminal extracellular/ SG luminal region remains unknown. This region contains a glucocorticoid-responsive regulated endocrine-specific protein 18 homologous domain (RESP18HD). We showed that RESP18HD is necessary and sufficient for the sorting of ICA512 to SGs of rat insulinoma INS-1 cellsa,b and that it binds with high-affinity to insulin and proinsulinb. In previus work we further studied the co-aggregation properties of soluble RESP18HD and insulin in in-vitro conditions that mimicked changes in pH and Zn2+ along the secretory pathway of β-cells. Fluorescence lifetime imaging-fluorescence resonance energy transfer (FLIM-FRET) microscopy was used to measure the interaction between RESP18HD-TQ2 and Insulin-Venus fusion proteins in INS-1 cells. RESP18HD aggregates in a pH-dependent manner with a pronounced aggregation at pH 6.8. In this condition we observed the formation of complexes between insulin and RESP18HD. Acidification reversed or completely dissolved these complexes. We are currently studying the effect of Zn2+ on RESP18HD and insulin co-aggregation. Moderate interaction of RESP18HD-TQ2 with Insulin-Venus in SGs was corroborated by FLIM-FRET in INS-1 cells. These results are consistent with the hypothesis that the interaction of ICA512-RESP18HD with pro/insulin (and possibly other SG cargoes) may contribute to phase-separation of high-order multiprotein assemblies for efficient biogenesis of SGs.