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

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 valineglycine-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.

Elastin-derived peptide VGVAPG decreases differentiation of mouse embryo fibroblast (3T3-L1) cells into adipocytes

“…Because resistin is strictly controlled by PPARγ activation, our data allow to assume that VGVAPG peptide by interaction with this receptor can control resistin gene expression [88]. Interaction between PPARγ and VGVAPG has been proven in our previous study, in which VGVAPG peptide was shown to affect PPARγ expression and PPARγ-mediated effects in mouse astrocytes and SH-SY5Y cells [31,49]. As mentioned above, PPARγ is involved in resistin expression, which is strictly related to obesity and type 2 diabetes.…”

“…To date, previous studies have shown that EDPs and/or VGVAPG peptide increase the production and/or secretion inflammatory markers such as IL-1α, IL-1β, and IL-6 in ligamentum flavum cells, synovial cells, and melanoma cell lines [ 63 – 65 ]. On the other hand, our previous studies show that VGVAPG peptide increases the expression of PPARγ and decreases the expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and production of IL-1β in mouse astrocytes in a PPARγ-dependent manner, which suggest that the effect of VGVAPG is tissue dependent [ 31 , 66 ]. Interestingly, our latest study revealed that caspase-1 activity increases, which suggests that this caspase does not play an inflammatory role in mouse astrocytes [ 66 ].…”

“…It has been shown that EDPs and/or VGVAPG induce some biological effects such as cell proliferation, migration, differentiation, and inflammation through EBP activation [ 2 , 28 – 30 ]. Recently, it has been reported that VGVAPG peptide affects peroxisome proliferator-activated receptor gamma (PPARγ) mRNA and protein expression [ 31 ]. Furthermore, similar to EDPs, PPARγ is involved in cell proliferation, migration, and differentiation and most importantly in adipocyte differentiation [ 32 ].…”

The VGVAPG Peptide Regulates the Production of Nitric Oxide Synthases and Reactive Oxygen Species in Mouse Astrocyte Cells In Vitro

“…The effect of Pioglitazone was reversed by 10 nM of the VGVAPG peptide. Our previous research showed that 50 nM of the VGVAPG peptide decreased peroxisome proliferator-activated receptor gamma (Pparγ) expression caused by Pioglitazone and Rosiglitazone [ 34 ]. Such data suggest that VGVAPG activates molecular pathways that may then compete with other pathways activated by PPARγ agonists.…”

“…The effectiveness of Glb1 mRNA silencing with the use of 50 nM specific siRNA was verified by measuring the mRNA levels. Previously, knockdown of the Glb1 gene was estimated at 39% of the control mRNA and 60.05% of the control protein as described in [ 33 , 34 ]. In present manuscript knockdown of the Glb1 gene was estimated at 37.45% of the control mRNA (data not shown).…”