Impact of elastin-derived VGVAPG peptide on bidirectional interaction between peroxisome proliferator-activated receptor gamma (Ppar\u03b3) and beta-galactosidase (\u03b2-Gal) expression in mouse cortical astrocytes in vitro

Konrad A Szychowski,Jan Gmiński

doi:10.1007/s00210-018-1591-4

Abstract

The process of degradation of the elastin-rich extracellular matrix produces elastin-derived peptides (EDPs). Different types of EDPs are detectable in the cerebrospinal fluid in healthy individuals and in patients after ischemic stroke. To date, it has been demonstrated that EDPs can regulate the development of insulin resistance in mice in a peroxisome proliferator-activated receptor gamma (Pparγ)-dependent manner. Therefore, the aim of this study was to investigate the impact of the elastin-derived valine-glycine-valine-alanine-proline-glycine (VGVAPG) peptide on Pparγ and beta-galactosidase (β-Gal) expression in mouse cortical astrocytes in vitro. Primary astrocytes were maintained in DMEM/F12 without phenol red supplemented with 10% fetal bovine serum. The cells were exposed to 50 nM, 1 and 50 μM of the VGVAPG peptide. After 3 and 6 h (for mRNA) and 24 and 48 h (for the protein) of exposition to the peptide, the expression of Pparγ and β-Gal was measured. Moreover, the siRNA gene knockdown method was applied. Our study showed, for the first time, that the VGVAPG peptide affected β-Gal and Pparγ mRNA and protein expression in mouse astrocytes in vitro. Furthermore, we suggested a bidirectional interaction between Pparγ and β-Gal. Both pioglitazone and rosiglitazone increased β-Gal and Pparγ protein expression in mouse astrocytes in vitro, and this effect was reduced by the VGVAPG peptide. However, due to the lack of sufficient data explaining the molecular mechanism of action of the VGVAPG peptide in the nervous system, more studies are necessary in this field.

Highlights

Elastin is the main component of the extracellular matrix in mammalian organisms
Pparγ protein expression decreased after stimulation with 1 and 50 μM of the VGVAPG peptide (Fig. 2a)
Pparγ protein expression increased after stimulation with 50 nM and 1 μM of the VGVAPG peptide (Fig. 2b)

Summary

Introduction

Elastin is the main component of the extracellular matrix in mammalian organisms. Degradation of the elastin-rich extracellular matrix by numerous proteinases leaking from the serum and secreted from the infiltrating platelets, leukocytes, activated vascular cells or the ageing process produce elastin-derived peptides (EDPs) (Mochizuki et al 2002). It has been demonstrated that VGVAPG induces diverse biological effects such as cell proliferation, migration and differentiation through activation of EBP (Senior et al 1984; Blood et al 1988; Jung et al 1998; Pocza et al 2008). Activation of this receptor results in progression of the atherosclerotic process (Maurice et al 2013). To date, only one paper investigated the role of the VGVAPG peptide and activation of EBP in normal astrocytes (Szychowski et al 2018)

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