Global protein and histone arginine methylation are affected in a tissue-specific manner in a rat model of diet-induced hyperhomocysteinemia

Abstract

Accumulation of S-adenosylhomocysteine (AdoHcy), the homocysteine (Hcy) precursor and a potent methyltransferase inhibitor, may mediate the neurological and vascular complications associated with elevated Hcy. Protein arginine methylation is a crucial post-translational modification and generates monomethylarginine (MMA) and dimethylarginine (asymmetric, ADMA, and symmetric, SDMA) residues. We aimed at determining whether protein arginine methylation status is disturbed in an animal model of diet-induced hyperhomocysteinemia (HHcy). HHcy was achieved by dietary manipulation of Wistar rats: methionine-enrichment (HM), B vitamins deficiency (LV), or both (HMLV). Total Hcy, S-adenosylmethionine (AdoMet), AdoHcy, MMA, ADMA and SDMA concentrations in plasma or tissues (heart, brain and liver) were determined by adequate high-performance liquid chromatography or liquid chromatography-electrospray ionization-tandem mass spectrometry methods. Moreover, in tissues from the HMLV group, histone arginine asymmetric dimethylation was evaluated by Western blotting, and the histone methylation marks H3R17me2a, H3R8me2a and H4R3me2a were studied. HHcy was induced by all special diets, with elevation of AdoHcy concentrations in liver (LV and HMLV) and heart (HMLV) (all versus control). Plasma ADMA levels were lower in all hyperhomocysteinemic animals. Protein-incorporated ADMA levels were decreased in brain and in heart (both for the LV and HMLV groups). Moreover, in brain of animals exposed to the HMLV diet, the H3R8me2a mark was profoundly decreased. In conclusion, our results show that diet-induced Hcy elevation disturbs global protein arginine methylation in a tissue-specific manner and affects histone arginine methylation in brain. Future research is warranted to disclose the functional implications of the global protein and histone arginine hypomethylation triggered by Hcy elevation.

Inhibition of Cellular Methyltransferases Promotes Endothelial Cell Activation by Suppressing Glutathione Peroxidase 1 Protein Expression

“…GPx-1 overexpression decreased ADA-induced adhesion molecule upregulation, whereas its knockdown augmented the effects of hypomethylation on adhesion molecule up-regulation. 5 Um isoform. In the right panel, cells exposed to ADA are lacking the peak corresponding to the later-eluting mcm 5 Um isoform.…”

“…The aminoacylated seryl-tRNA was fractionated on an RPC-5 column, first in the absence of Mg 2ϩ and subsequently in the presence of Mg 2ϩ . Using this sequential chromatography approach, it is possible to quantify the relative tRNA [Ser]Sec to the total tRNA Ser and separate the two major isoforms of tRNA [Ser]Sec , mcm 5 U and mcm 5 Um (35,36). Statistics-Statistical analysis was performed on experiments repeated in three to five independent assays.…”

“…7A) (21). The mcm 5 Um isoform of tRNA [Ser]Sec has been shown to be required for the expression of stress-related selenoproteins, which include GPx-1 (21,23 Um isoform is practically undetectable (Fig. 7B, right panel), suggesting that ADA treatment blocks the formation of the critical isoform of tRNA…”

“…The mammalian tRNA [Ser]Sec population consists of two major isoforms that differ by a single methyl group on the ribosyl moiety at position 34, 2Ј-O-methylribose (21). The highly modified base at position 34 is 5-methoxycarbonylmethyluridine (mcm 5 U), and, thus, the two isoforms are designated mcm 5 U and 5-methoxycarbonylmethyl-2Ј-O-methyluridine (mcm 5 Um) (21). Loss of the isopentenyladenosine (iA6) at position 37 (e.g.…”

146 Demethylation Treatment Restores Erectile Function in a Rat Model of Hyperhomocysteinemia

“…31,32 Measurement of NO The NO and cyclic guanosine monophosphate (cGMP) concentration in corpus cavernosum were evaluated with spectrophotometry method, using a commercial kit (Boster, Wuhan, China), following the protocols provided by the manufacturer.…”