Study of the transcriptional activity of transposon LINE1 under chronic exposure to cadmium chloride

Introduction. Transposons are DNA sequences capable of moving through the genome. LINE1 is the only autonomous transposon that is still actively replicated in humans, thus playing a key role in the evolution and regulation of the genome. The experts have observed increased mobility of LINE1 as a result of exposure to certain known carcinogens, such as heavy metals, benz(a)pyrene and bisphenol A.

The study aims to research the expression level of LINE1 transposons in the kidneys and liver of model animals exposed to chronic exposure to various doses of cadmium chloride.

Materials and methods. Five groups of Wistar rats (72 in total, 7 males and 7 females in the experimental groups and 8 males and 8 females in control group) were formed for the experiment. Experimental groups received a cadmium chloride solution in water at doses of 0.001, 0.01, 0.1, and 1 mg/kg.

Results. The authors observed a dose-dependent increase in the level of LINE1 transcription, but statistical analysis did not show a significant increase in the level of relative transposon expression. The evaluation of the variances revealed significant differences from the control group in animals exposed to high doses of the toxicant. There are weak associations between the levels of relative expression of metallotineins and transposon genes.

Limitations. The study was conducted on rats, and its results cannot be automatically transferred to humans. The obtained levels of relative transposon expression are highly susceptible to random fluctuations, which, together with the small size of the studied sample, necessitates further research on a larger sample in order to obtain more reliable results.

Conclusion. The results obtained suggest the presence of cadmium-induced activation of transposon LINE1 transcription in rat organs, but the result did not reach the level of statistical significance. At the same time, the increase in variance in the experimental groups suggests that activation depends on a variety of factors mediating the response to toxic effects.

Ethics. The study was approved by the bioethical Commission of the Ufa Research Institute of Occupational Health and Human Ecology on 11.12.2023 No. 01-12. Throughout the study, the animals were kept in standard conditions with twelve hours of artificial light during the daytime, a relatively constant humidity level (30–70%) and an air temperature of plus 20–25°C. Manipulations with all animals were carried out strictly in compliance with the rules set out in the basic regulatory documents, including the "European Convention for the Protection of Vertebrate Animals Used for Experimental and Other Scientific Purposes" (Strasbourg, 1986) and the Helsinki Declaration on Humane Treatment of Animals.

Contributions:
Karimov D.D. — research concept and design, PCR, material collection and processing, statistical data processing, text writing, editing;
Mukhammadieva G.F. — RNA isolation, PCR, material collection, editing;
Ryabova Yu.V. — concept and design of research, organization of experiment, collection of material;
Repina E.F. — concept and design of research, collection and processing of material;
Gizatullina A.A. — conducting PCR, collecting material, editing;
Smolyankin D.A. — conducting experiments on animals, collecting material;
Karimov D.O. — research concept and design, experimental organization, statistical data processing, editing.

Funding. Industry research program of the Federal Service for Supervision of Consumer Rights Protection and Human Well‑being for 2021-2025, p. 6.1.9 "Experimental substantiation of highly sensitive markers of toxic metal exposure to the body and development of preventive measures".

Conflict of interest. The authors declare no conflict of interest.

Received: 29.12.2025 / Accepted: 28.04.2026 / Published: 02.06.2026

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