The lack of transcriptionally active Nrf2 triggers colon dysfunction in female mice - The role of estrogens.

BACKGROUND AND AIM: The proper functioning of the gastrointestinal system relies on an intricate crosstalk between a plethora of cell types and signaling pathways. Recently we identified that the lack of NRF2 transcriptional activity (NRF2 tKO) triggers significant colon microscopical alterations, still they do not affect the general functioning of mice. Therefore, in this study, we aimed to address the gender-dependent impact of NRF2 transcriptional deficiency on colon function, and relate them to an established model of inflammatory bowel disease (IBD). METHODS: In the study we subjected 3- and 6-month old mice deficient in IL-10 and NRF2 transcriptional activity and wild-type counterparts to tests assessing colon functionality, and histological analyses. To address the role of estrogens, we attempted to rescue the phenotype by the delivery of 17ß-estradiol through subcutaneous implants. RESULTS: In females, NRF2 transcriptional abrogation, like IL-10 deficiency, triggers a functional and microscopic phenotype, that resembles IBD. The females are significantly more affected by the dysfunctional phenotype, and the functional impairmentdecreases with age. We found that NRF2 transcriptional activity influences 17ß-estradiol level and the estrogen receptors expression and location. Exogenous delivery of 17ß-estradiol normalized colon motility in the NRF2 tKO mice, which is related to enhanced ERß signaling. CONCLUSIONS: Summing up, in this study, we underline that NRF2 transcriptional deficiency or the lack of IL-10 results in pronounced GI functional decline in young females. Mechanistically, we show that the impaired distal colon motility is dependent on ERß signaling. Targeting estrogen signaling seems a promising therapeutic strategy to counteract colonic dysfunction.

Nrf2 Transcriptional Activity Governs Intestine Development.

Our recent findings indicate that Nrf2 transcriptional activity is essential in maintaining the proper large intestinal structure in adult mice. Here, we aimed to verify whether Nrf2-related intestine abnormalities stemmed from the early weaning or gestational periods. Therefore, we analyzed 4-day-old pups and embryos devoid of Nrf2 transcriptional activity (tKO) and their wild-type counterparts. We found significant changes in the intestinal structure of 4-day-old Nrf2 tKO pups including a longer colon, altered crypt distribution, and enlargement of the goblet cells with a markedly higher level of mucin 2. Tracing back the origin of these alterations, we observed that they appeared as early as day 14.5 of embryonic development, independently of sex. Importantly, in this period, we observed a significant increase in the Nrf2 level and a distinctive, untimely pattern of expression of the proliferation factor Ki67. At the latest stage of embryonic development, we detected a premature drop in the differentiation factor Notch1. We suspect that intestine abnormalities in mice lacking Nrf2 transcriptional activity stem from sex-independent disturbed intestinal cell proliferation and could be further exacerbated by altered differentiation. Summing up, we identified Nrf2 transcriptional activity as an important regulator of intestinal formation. It influences the hindgut cell proliferation and differentiation at different stages of embryonic development.

Thioglycoligation of aromatic thiols using a natural glucuronide donor.

The ß-d-glucuronidase DtGlcA from Dictyoglomus thermophilum was engineered to generate an active thioglycoligase that is able to catalyse the formation of numerous S-glucuronides. Its X-ray structure analysis indicated the ability of the biocatalyst to bind aromatic thiol acceptors for S-glycosylation. Noteworthily, the DtGlcA mutant was found to be the first thioligase that is able to use a natural sugar donor different from the widely used synthetic para-nitrophenyl glycosides.

Structure of two crystal forms of sheep ß-lactoglobulin with EF-loop in closed conformation.

Ovine ß-lactoglobulin has been isolated from whey fraction of sheep milk and crystallized. The high-resolution structures of two crystal forms (triclinic and trigonal) obtained at pH 7.0 have been determined revealing that ovine protein, similarly to its bovine analog, is dimeric. Access to the binding site located in the eight-stranded antiparallel ß-barrel in both structures is blocked by the EF loop that has been found in closed conformation. Similarly to bovine lactoglobulin (BLG), conformation of the EF loop is stabilized by hydrogen bond between Glu89 and Ser116 indicating that Tanford transition might occur with the same mechanism. The substitution at six positions in relation to the most abundant isoform B of BLG also affects the distribution of electrostatic potentials and the total charge.

Serum level of the circulating angiogenesis inhibitor endostatin in patients with hyperthyroidism or hypothyroidism.

Serum level of endostatin, a natural angiogenesis inhibitor, was measured in 12 patients with hyperthyroidism and 9 patients with hypothyroidism. Control values were obtained from 12 healthy individuals. Hyperthyroidism was shown to be associated with an increased level of endostatin and hypothyroidism with a decreased endostatin level. There was no correlation of serum endostatin with thyroid hormone levels. Endostatin is a fragment of type XVIII collagen, and it is possible that reported changes are related to the effect of thyroid hormones on connective tissue metabolism.