Development is a dynamic process characterized by critical periods in which organ systems are sensitive to changes in the surrounding environment. In the current study, critical windows of embryonic growth and kidney development were assessed in the embryonic chicken. All‐trans retinoic acid (tRA) influences not only organogenesis and cell proliferation, but also targets metanephric kidney nephrogenesis. Embryonic chickens were given a single injection of tRA on embryonic day 8. tRA decreased embryo, kidney, and heart mass from day 16 to day 18. However, mass specific kidney and heart masses showed no differences. Whole blood, plasma, and allantoic fluid osmolality were altered in tRA treated embryos from day 16 to day 18. In addition, hematocrit, red blood cell count, and hemoglobin concentration were altered in tRA treated embryos. The results suggest that although nephrogenesis was not affected by tRA, the developing osmoregulatory system was altered in tRA treated embryos.

No description available.

Vitamin A and its derivatives, collectively termed retinoids, are essential for proper growth and development as well as maintenance of homeostasis in the adult. Retinoic acid (RA), the major biologically active vitamin A metabolite, is well characterized for its crucial roles in gene activation during embryogenesis. Our lab had previously performed a microarray analysis to identify genes induced by exogenous RA in the tailbud of early mouse embryos. Three genes were chosen from the microarray results for further investigation; Germ Cell Nuclear Factor (GCNF/NR6A1), Prickle1 (Pk1) and Ror2, the latter of which are known members of the planar cell polarity (PCP) pathway. These genes were further examined for RA regulation by embryo culture and RT-PCR, which strongly supported a direct regulatory mechanism of NR6A1 by RA. Further analysis aiming to identify a functional response element in the promoter of the targets was attempted, including chromatin immunoprecipitation (ChIP), made possible by the generation and characterization of a highly specific antibody against RARγ. This antibody was used in a ChIP promoter walk, which identified regions on target gene promoters that are occupied by RARγ in vivo, and therefore likely harbor RA response elements.

No description available.

Vitamin A and its derivatives, collectively termed retinoids, are essential for proper growth and development as well as maintenance of homeostasis in the adult. Retinoic acid (RA), the major biologically active vitamin A metabolite, is well characterized for its crucial roles in gene activation during embryogenesis. Our lab had previously performed a microarray analysis to identify genes induced by exogenous RA in the tailbud of early mouse embryos. Three genes were chosen from the microarray results for further investigation; Germ Cell Nuclear Factor (GCNF/NR6A1), Prickle1 (Pk1) and Ror2, the latter of which are known members of the planar cell polarity (PCP) pathway. These genes were further examined for RA regulation by embryo culture and RT-PCR, which strongly supported a direct regulatory mechanism of NR6A1 by RA. Further analysis aiming to identify a functional response element in the promoter of the targets was attempted, including chromatin immunoprecipitation (ChIP), made possible by the generation and characterization of a highly specific antibody against RARγ. This antibody was used in a ChIP promoter walk, which identified regions on target gene promoters that are occupied by RARγ in vivo, and therefore likely harbor RA response elements.

No description available.

Cancer is the second leading cause of death in America. In 2018, there were 9.5 million deaths due to cancer according to the International Agency for Research on Cancer (IARC), and this number is expected to grow to 16.3 million by 2040. Among the type of cancers, neuroblastoma and nerve tissue cancers have a 5-year survival rate of 33%, which is very low. One of the main issues linked to such situations is due to the lack of specificity in removing tumor cells. While clinical therapies work to reduce tumor mass as much as possible, they cannot always target all of them, and once some cancer cells are left behind, they regrow and spread. The work of this thesis seeks to enhance the treatment outcome by utilizing all-trans retinoic acid (ATRA), a metabolite of vitamin A, to induce differentiation of nerve tissue cancer cells and eliminate their ability to self-renew (reemerge). Differentiation therapy is currently utilized in select clinical applications but the utilization of ATRA is limited due to its poor solubility in the blood, low bioavailability, short half-life, and in vivo toxicity. In order to alleviate some of these issues, the ATRA molecule was engineered with a novel cell penetrating peptide and tested for its efficacy. Data and results presented herein report the differentiation induced by the CPP-conjugated ATRA may act as a viable method for neuroblastoma treatment. / Bioengineering

Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

Retinoic acid receptor (RAR), a member of the steroid/thyroid hormone nuclear receptor superfamily, functions as a RA-dependent transcription activator bound to the RA response element (RARE) within the promoter or enhancer region of target genes. The transcriptional activity of RAR is modulated by a large number of coregulators including coactivators and corepressors. Acinus is a nuclear protein with three isoforms (Acinus-L, Acinus-S and Acinus-S'). Acinus-S' interacts with the A/B domain of RAR and represses RAR-regulated genes expression. Acinus (without isoform definition) has been identified as a component of nuclear speckles, the spliceosome and the exon junction complex (EJC), suggesting its localization in nuclear speckles and involvement in RNA processing. Acinus-S has been shown to localize in nuclear speckles. However, it is unclear whether the other two isoforms also localize in nuclear speckles. In addition, the role of Acinus in regulating pre-mRNA splicing is unclear. The goal of these studies was to examine the nuclear localization of Acinus-L and Acinus-S' and to determine the role of Acinus isoforms in RAR-dependent splicing. The sub-nuclear localization of Acinus-L and Acinus-S' was determined using fluorescence microscopy. Acinus-S' colocalizes with SC35 in nuclear speckles while Acinus-L localizes diffusely throughout the nucleoplasm. RA treatment has little effect on the sub-nuclear localization of Acinus-L and Acinus-S'. The domains/regions necessary for the distinct sub-nuclear localization of Acinus-L and Acinus-S' were identified. The speckled sub-nuclear localization of Acinus-S' is dependent on its C-terminal RS- and RD/E-rich region but is independent of the phosphorylation status of Ser-453 and Ser-604 within this region. The unique N-terminal SAP-motif of Acinus-L is responsible for its diffuse localization in the nucleus. Moreover, the sub-nuclear localization of Acinus isoforms is affected by each other, which is determined by the combinatorial effect of the more potent SAP motif of Acinus-L and the C-terminal RS- and RD/E-rich region in all Acinus isoforms. The C-terminal RS- and RD/E-rich region of Acinus mediates the colocalization of Acinus isoforms as well as with its interacting protein RNPS1. The role of Acinus isoforms in regulating pre-mRNA splicing was explored using in vivo splicing assays. Both Acinus-L and Acinus-S', with the activity of Acinus-L higher than that of Acinus-S', increase the splicing of a RA-responsive minigene containing a weak 5' splice site but not a RA-responsive minigene containing a strong 5' splice site. RA treatment further enhances the splicing activity of Acinus in a dose- and time-dependent manner, suggesting a RA-dependent activity in addition to a RA-independent activity of Acinus. The RA-independent effect of Acinus on the splicing of pre-mRNAs containing the weak 5' splice site occurs to varying degrees using minigene constructs containing several different promoters while the RA-dependent splicing activity of Acinus is specific for transcripts derived from the minigene driven by the RARE-containing promoter. This suggests that the ligand-dependent splicing activity of Acinus is related to the RA-activated RAR bound to the RARE. The ligand-dependent splicing activity of Acinus was further shown to be promoter-specific, depending on the ligand-dependent transcription activator. The RRM domain was identified to be necessary for the RA-dependent splicing activity of Acinus. The RA-independent splicing activity of Acinus is repressed by RNPS1. Unexpectedly, the C-terminal RS- and RD/E rich region is dispensable for the splicing activity of Acinus in regulating the minigene containing a weak 5' splice site. Importantly, measurement of the splicing of endogenous human RARâ and Bcl-x in vivo demonstrates that Acinus stimulates the use of the weaker alternative 5' splice site of these two genes in a RA-dependent manner for RARâ and in a RA-independent manner for Bcl-x. Taken together, these studies demonstrate the distinct sub-nuclear localization of Acinus-L and Acinus-S', and identified the domains that are responsible for their sub-nuclear localization, which shed light on possible distinct functions between Acinus isoforms. In addition, both Acinus-L and Acinus-S' have been shown to be splicing cofactors (with the activity of Acinus-L higher than that of Acinus-S') that facilitate constitutive splicing of pre-mRNAs containing a weak 5' splice site and regulate alternative splicing in favor of the isoform generated from the weaker alternative 5' splice site. Both Acinus-L and Acinus-S' have a RA-dependent splicing activity specific for RA-responsive genes, which suggests that Acinus functions in RAR-dependent splicing. / Biochemistry