Targeted Expression to Liver of an antimiR-33 Sponge as a Gene Therapy Strategy against Hypercholesterolemia: In Vitro Study

Atherosclerosis is the leading cause of cardiovascular diseases in Mexico and worldwide. The membrane transporters ABCA1 and ABCG1 are involved in the reverse transport of cholesterol and stimulate the HDL synthesis in hepatocytes, therefore the deficiency of these transporters promotes the acceleration of atherosclerosis. MicroRNA-33 (miR-33) plays an important role in lipid metabolism and exerts a negative regulation on the transporters ABCA1 and ABCG1. It is known that by inhibiting the function of miR-33 with antisense RNA, HDL levels increase and atherogenic risk decreases. Therefore, in this work, a genetic construct, pPEPCK-antimiR-33-IRES2-EGFP, containing a specific antimiR-33 sponge with two binding sites for miR-33 governed under the PEPCK promoter was designed, constructed, and characterized, the identity of which was confirmed by enzymatic restriction, PCR, and sequencing. Hep G2 and Hek 293 FT cell lines, as well as a mouse hepatocyte primary cell culture were transfected with this plasmid construction showing expression specificity of the PEPCK promoter in hepatic cells. An analysis of the relative expression of miR-33 target messengers showed that the antimiR-33 sponge indirectly induces the expression of its target messengers (ABCA1 and ABCG1). This strategy could open new specific therapeutic options for hypercholesterolemia and atherosclerosis, by blocking the miR-33 specifically in hepatocytes.

Strategies for Targeting Gene Therapy in Cancer Cells With Tumor-Specific Promoters

Cancer is the second cause of death worldwide, surpassed only by cardiovascular diseases, due to the lack of early diagnosis, and high relapse rate after conventional therapies. Chemotherapy inhibits the rapid growth of cancer cells, but it also affects normal cells with fast proliferation rate. Therefore, it is imperative to develop other safe and more effective treatment strategies, such as gene therapy, in order to significantly improve the survival rate and life expectancy of patients with cancer. The aim of gene therapy is to transfect a therapeutic gene into the host cells to express itself and cause a beneficial biological effect. However, the efficacy of the proposed strategies has been insufficient for delivering the full potential of gene therapy in the clinic. The type of delivery vehicle (viral or non viral) chosen depends on the desired specificity of the gene therapy. The first gene therapy trials were performed with therapeutic genes driven by viral promoters such as the CMV promoter, which induces non-specific toxicity in normal cells and tissues, in addition to cancer cells. The use of tumor-specific promoters over-expressed in the tumor, induces specific expression of therapeutic genes in a given tumor, increasing their localized activity. Several cancer- and/or tumor-specific promoters systems have been developed to target cancer cells. This review aims to provide up-to-date information concerning targeting gene therapy with cancer- and/or tumor-specific promoters including cancer suppressor genes, suicide genes, anti-tumor angiogenesis, gene silencing, and gene-editing technology, as well as the type of delivery vehicle employed. Gene therapy can be used to complement traditional therapies to provide more effective treatments.

Effects of Bisphenol A on Foxl2 gene expression and DNA damage in adult viviparous fish Goodeaatripinnis

Bisphenol A (BPA) is an emerging pollutant of global concern. Viviparous fish Goodea atripinnis is endemic to the Central Mexican Plateau where BPA was detected; however, few studies examined the influence of this chemical on native viviparous fish. The effects of BPA (sublethal dose) were determined on DNA integrity and Foxl2 expression in G. atripinnis gonads, and interactions of BPA with FOXL2 protein. Genotoxicity analysis revealed that % comets, at 14 and 28 days and comet tail length (at 14 days) were significantly higher in exposed compared to controls. In general, the % DNA tail was not markedly higher in BPA-treated fish; however, tail moment related to tail length exhibited significant increases in DNA damage. RT-qPCR assays showed Foxl2 overexpression after 14 and 28 days of exposure in females; while in males, Foxl2 was overexpressed after 28 days. In silico analysis demonstrated that BPA interacted with seven residues located in FOXL2 homeodomain. In summary, sublethal BPA doses induced DNA damage and changes in Foxl2 expression in gonadal cells of G. atripinnis, which may adversely affect reproduction in BPA-exposed wild populations. Foxl2 overexpression and BPA-FOXL2 interaction suggested alterations in processes involving Foxl2. Viviparous fish may thus serve as potential non-conventional models for assessing pollutants effects.

[Lack of foto reactivation of the Haemophilus influenzae transforming DNA mutated with near ultraviolet light (325-400nm)]

Three extracts from Saccharomyces cerevisiae were obtained by salting out with ammonium sulfate, these were I-G, EFRL-II-G and III-G. Fraction EFRL-II-G showed the highest photoreactivating activity on DNA str2000 irradiated with far UV light. However, the same fraction did not reactivate DNA str2000 previously inactivated by near UV irradiation. We think that the inactivation by near-UV was not due to photochemically-formed pyrimidine dimers. Decrease in spontaneous mutation frequency of cells transformed with DNA str2000 irradiated with near-UV light, was the same with the DNA treated with active or heat inactivated EFRL-II-G, therefore we may conclude that DNA lesions responsible for the effect are difference to pyrimidine dimers.

[Decrease of spontaneous mutations in Haemophilus influenzae caused by transformation with its own DNA irradiated with near-ultraviolet light]

Transforming DNA containing the streptomycin resistance marker, was irradiated for 8 h with broad near ultraviolet light (325-400 nm) at pH 4.8, and the inactivation kinetics determined. After selection of streptomycin resistant transformants, they were grown until a turbidity of 150-200 Klett units. In these cultures we looked for new markers coming from the irradiated transforming DNA. We looked and found the novobiocin resistance marker and one that conveys to protoporphyrin IX utilization, measured as an increase in the mutation frequency of these markers in the streptomycin resistant population. In other experiments, we found a decline in spontaneous mutation frequency for the same markers in the cells transformed with irradiated DNA. This last finding rises the possibility of alterations on the mutator genes as a result of near ultraviolet irradiation.