CVB5 proteases 2A targets insulin granule biogenesis in MIN6 cells

KP Knoch; A Petzold; C Wegbrod; A Sönmez; C Münster; A Friedrich; Z Marinicova; J Merl-Pham; S Hauck; M Solimena

doi:10.1055/s-0038-1641934

Diabetologie und Stoffwechsel, Table of Contents

Diabetologie und Stoffwechsel 2018; 13(S 01): S59-S60
DOI: 10.1055/s-0038-1641934

Poster

Typ-1-Diabetes II

Georg Thieme Verlag KG Stuttgart · New York

CVB5 proteases 2A targets insulin granule biogenesis in MIN6 cells

Authors

KP Knoch

¹TU Dresden, Medizinische Fakultät, Paul Langerhans Institut Dresden, Molecular Diabetology, Dresden, Germany

²German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany, Neuherberg, Germany
A Petzold

¹TU Dresden, Medizinische Fakultät, Paul Langerhans Institut Dresden, Molecular Diabetology, Dresden, Germany

²German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany, Neuherberg, Germany
C Wegbrod

¹TU Dresden, Medizinische Fakultät, Paul Langerhans Institut Dresden, Molecular Diabetology, Dresden, Germany

²German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany, Neuherberg, Germany
A Sönmez

¹TU Dresden, Medizinische Fakultät, Paul Langerhans Institut Dresden, Molecular Diabetology, Dresden, Germany

²German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany, Neuherberg, Germany
C Münster

¹TU Dresden, Medizinische Fakultät, Paul Langerhans Institut Dresden, Molecular Diabetology, Dresden, Germany

²German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany, Neuherberg, Germany
A Friedrich

¹TU Dresden, Medizinische Fakultät, Paul Langerhans Institut Dresden, Molecular Diabetology, Dresden, Germany

²German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany, Neuherberg, Germany
Z Marinicova

¹TU Dresden, Medizinische Fakultät, Paul Langerhans Institut Dresden, Molecular Diabetology, Dresden, Germany

²German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany, Neuherberg, Germany
J Merl-Pham

³Research Unit Protein Science Helmholtz Center Munich, Munich, Germany
S Hauck

³Research Unit Protein Science Helmholtz Center Munich, Munich, Germany
M Solimena

¹TU Dresden, Medizinische Fakultät, Paul Langerhans Institut Dresden, Molecular Diabetology, Dresden, Germany

²German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany, Neuherberg, Germany

Abstract

Full Text

Background and aims:

Coxsackieviruses B (CVBs) are among the candidate environmental factors implicated in the pathogenesis of type 1 diabetes. Their cap-independent translation in β-cells relies on factors that are also implicated in the translation of insulin granule components (Knoch et al, 2014). Notably, CVB Infection of β-cells strongly reduces their insulin granule stores and release. Therefore, we are interested in elucidating how CVB proteases affect the traffic and stability of insulin granule cargoes.

Materials and methods:

MIN6 cells were transfected with either CVB5 protease 2A or 3C or infected with CVB5. Levels of insulin and other granule cargoes in control and CVB expressing cells were assessed by western blotting, ELISA, immunostaining and quantitative proteomics.

Results:

The levels of insulin and other granule markers were unaffected in MIN6 cells expressing CVB5 3C, while they were reduced in cells infected with CVB5 or transfected with CVB5 2A. Granule cargo depletion in CVB5 and CVB 2A expressing cells neither correlated with ER stress nor apoptosis. Proteomic analysis revealed instead the reduced levels of several factors involved in post-Golgi vesicular transport, such as Arf1, GGA2, Rab3b and Sytl4. However, only the knockdown of Rab3b and GGA2 resulted in a phenotype similar to the one observed upon overexpression of CVB5 2A.

Conclusions:

We propose that CVB 2A blocks insulin granule biogenesis from the Golgi complex. The depletion of newly-generated granules likely accounts for the reduction of insulin secretion in CVB-infected β-cells, while massive degradation of granule cargoes may affect their antigenic presentation.