The seasonal changes of the heme oxygenase in the retina pig

Heme oxygenase-1 gene rs2071746 polymorphism in retinal vein occlusion

BACKGROUND

Heme oxygenase-1 (HO-1) is an important cytoprotective enzyme due to its ability to degrade pro-inflammatory heme. The common single nucleotide polymorphism (SNP) rs2071746 on the HMOX1 gene has been associated with HO-1 activity and a variety of cardiovascular diseases. This study was performed to investigate the association between the rs2071746 SNP and retinal vein occlusion (RVO).

METHODS

We included 496 RVO patients and 297 control subjects in this case-control study. Genotypes of the rs2071746 polymorphism were determined by TaqMan assays.

RESULTS

There was no association between the rs2071746 genotype and the presence of RVO (p = .443). The lack of association was found in all three logistic regression models, namely the dominant (p = .560), the recessive (p = .373) and the co-dominant model (p = .444). The distribution of the rs2071746 genotype was 30% (AA), 51% (AT), and 19% (TT). Baseline characteristics were similar between these genotypes, except for diabetes mellitus, which was less prevalent in the AA genotype (p < .001).

CONCLUSION

The rs2071746 polymorphism does not seem to be a major risk factor for the presence of RVO.

Carbon Monoxide (CO) as a Retinal Regulator of Heme Oxygenases -1, and -2 (HO’s) Expression

Carbon monoxide (CO) has been proposed as a chemical light signal and neural system modulator via heme oxygenases -1 and -2 (HO-1 and HO-2). Many papers have proven the CO-HO circuit to be important for such physiological pathways as the molecular biological clock and the GnRH axis, but also in such pathological occurrences as ischemic injuries, or inflammation as a regenerative and neuroprotective factor. In this in vivo experiment, we used three groups of pigs: control—housed in natural conditions without any procedures; without CO—adapted and kept in constant darkness, infused with blank plasma; and with CO—adapted and kept in constant darkness infused with CO-enriched plasma. After the experiments, each animal was slaughtered and its eyes were collected for further analysis. Quantitative PCR and Western blot analysis were performed to show statistical differences in the expressions between the experimental groups. Our data revealed that exogenous CO is regulator of mRNA transcription for HO-1 and HO-2 and PCNA. Moreover, the mRNA abundance of analyzed factors in the experimental group after CO elevation revealed a restored gene-expression level similar to the control group, which we had observed in the group’s restored protein level after CO elevation. In conclusion, exogenous CO regulates HO’s and PCNA gene expression on transcriptional and translational levels in a similar way as a light cue.

Role of Methylation in Period2 (PER2) Transcription in the Context of the Presence or Absence of Light Signals: Natural and Chemical-Studies on the Pig Model

It has been proposed that carbon monoxide (CO) is a chemical light carrier that is transferred by the humoral pathway from the retina to the brain. Here, we aimed to study how deeply CO is involved in regulating the expression of Period2 gene (PER2), one of the genes maintaining the intrinsic biological clock. In our in vivo experiment, we studied whether CO may be a chemical signal and is also equivalent to natural light in three groups of pigs: Normal: housed in natural conditions without any procedures, Control: adapted and kept in constant darkness, infused with blank plasma, and CO treated: adapted and kept in constant darkness infused with CO-enriched plasma. After the experiment, the animals were slaughtered at two times of day: 12 p.m. and 12 a.m. Next, hypothalamus samples were collected. Quantitative PCR, the DNA methylation of the promoter sequence containing enhancers (E-box) and a functional analysis of the PER2 promoter was performed. qPCR showed a differential pattern of PER2 mRNA expression at daytime oscillation in the examined groups. Pyrosequencing revealed daytime changes in the methylation level of regulatory sites of the examined sequence. Luciferase reporter assay confirmed that E-boxes (CANNTG) drive the expression of the porcine PER2 in vitro. In conclusion, changes in methylation over 24 h may regulate the oscillatory manner of PER2 expression.