Bleomycin hydrolase and hyperhomocysteinemia modulate the expression of mouse proteins involved in liver homeostasis

Abstract

The liver is the major contributor to homocysteine (Hcy) metabolism and fatty liver disease is associated with hyperhomocysteinemia. Bleomycin hydrolase (Blmh) is an aminohydrolase that also participates in Hcy metabolism by hydrolyzing Hcy-thiolactone. To gain insight into hepatic functions of Blmh, we analyzed the liver proteome of Blmh(-/-) and Blmh(+/+) mice in the absence and presence of diet-induced (high methionine) hyperhomocysteinemia using 2D IEF/SDS-PAGE gel electrophoresis and MALDI-TOF mass spectrometry. We identified eleven liver proteins whose expression was significantly altered as a result of the Blmh gene inactivation. The differential expression (Blmh(-/-) vs. Blmh(+/+)) of four liver proteins was lower, of two proteins was higher, and was further modified in mice fed with a hyperhomocysteinemic high-Met diet. The down-regulated proteins are involved in lipoprotein metabolism (ApoA1, ApoE), antigen processing (Psme1), energy metabolism (Atp5h, Gamt), methylglyoxal detoxification (Glo1), oxidative stress response (Sod1), and inactivation of catecholamine neurotransmitters (Comt). The two up-regulated proteins are involved in nitric oxide generation (Ddah1) and xenobiotic detoxification (Sult1c1). We also found that livers of Blmh(-/-) mice expressed a novel variant of glyoxalase domain-containing protein 4 (Glod4) by a post-transcriptional mechanism. Our findings suggest that Blmh interacts with diverse cellular processes-from lipoprotein metabolism, nitric oxide regulation, antigen processing, and energy metabolism to detoxification and antioxidant defenses-that are essential for liver homeostasis and that modulation of these interactions by hyperhomocysteinemia underlies the involvement of Hcy in fatty liver disease.

Folate Deficiency Was Associated with Increased Alanine Aminotransferase and Glutamyl Transpeptidase Concentrations in a Chinese Hypertensive Population: A Cross-Sectional Study

“…HHcy was an independent risk factor for cardiovascular diseases. The damage effect of elevated serum Hcy on NAFLD and other liver damage had also been verified both in epidemiological and clinical studies (7,14), and also in animal experiments (26). The range of Hcy in the present study was 13.2 (9.9-15.9).…”

Paraoxonase 1 deficiency and hyperhomocysteinemia alter the expression of mouse kidney proteins involved in renal disease

“…These findings suggest that while in the kidney and liver the antioxidant defense is enhanced by a high-Met diet, in the brain the antioxidant defense is compromised. The other proteins that were identified as differentially expressed in the kidney (Table 1) were not regulated by the Pon1 −/− genotype and/or high-Met diet in the liver [24] or brain [25]. Pebp1 was up-regulated in the kidney and down-regulated in the brain both by the Pon1 −/− genotype and highMet diet (Supplementary Table S2).…”

“…Plasma ApoA-I is also known to be down-regulated in a dietary HHcy mouse model [27], similar to the one used in the present work. Further, in our previous work we found that hepatic ApoA-I is down-regulated by a high-Met diet in wild type mice [24].…”

“…Protein sample preparation, 2D-IEF/SDS-PAGE analyses, and protein identification by MALDI-TOF mass spectrometry [23][24][25] were carried out as described in the Supplementary Methods.…”

Paraoxonase 1 and dietary hyperhomocysteinemia modulate the expression of mouse proteins involved in liver homeostasis.

“…Protein extraction. Liver proteins were extracted using the phenol method (Faurobert et al, 2007) as previously described (Suszynska-Zajczyk et al, 2014a). Briefly, liver tissue was disintegrated by grinding with dry ice using a mortar and pestle.…”