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Michal Gorzkiewicz,1,2 Monika Marcinkowska,1 Maciej Studzian,3,4 Iwona Karwaciak,4,5 Lukasz Pulaski,3,4 Barbara Klajnert-Maculewicz1 1Department of General Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland; 2Department of Molecular Medicine II, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; 3Department of Oncobiology and Epigenetics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland; 4Laboratory of Transcriptional Regulation, Institute of Medical Biology PAS, Lodz, Poland; 5Laboratory of Epigenetics, Institute of Medical Biology PAS, Lodz, PolandCorrespondence: Michal Gorzkiewicz, Department of General Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 141/143 Pomorska Street, Lodz, 90-236, Poland, Tel +48 42 635 41 47, Email michal.gorzkiewicz@biol.uni.lodz.plBackground: Mesalazine is one of the main drugs used to treat inflammatory bowel diseases. However, its applicability is limited by its rapid inactivation and removal from the organism, as well as the need for its membrane transporter-dependent cellular uptake to exert therapeutic effect. The present study involved the development of an innovative nanocarrier, based on poly(amidoamine) (PAMAM) dendrimer of the 4th generation, to obtain higher concentrations of the drug in the intestinal epithelial cells, thus increasing its anti-inflammatory potential. The work involved synthesis and in vitro characterization of covalent PAMAM-mesalazine conjugate with succinic linker.Results: PAMAM-mesalazine conjugate was synthesized and characterized by 1H NMR, 13C NMR, FTIR and MALDI-TOF MS. This allowed to confirm the purity of the obtained compound and intermediates. Based on the analyses, it was found that ~45 drug molecules were successfully attached to one molecule of PAMAM dendrimer. The conjugate was then characterized in terms of hydrodynamic diameter, zeta potential, spectral pro

Smad proteins are major components in the intracellular signaling pathway of transforming growth factor-beta (TGF-beta), and phosphorylation is an important mechanism in regulation of their functions. Smad7 was identified as a potent inhibitor of TGF-beta-dependent signaling. We have identified serine 249 in Smad7 as a major phosphorylation site, the phosphorylation of which was not affected by TGF-beta1. Abrogation of the phosphorylation by substitution of Ser-249 with alanine or aspartic acid residues did not affect the ability of Smad7 to inhibit TGF-beta1 and BMP7 signaling. No differences were found in the stability or in the intracellular distribution of Smad7 mutants compared with the wild-type molecule. However, Smad7 fused to the DNA-binding domain of GAL4 induced transcription from a reporter with mutated TATA minimal promoter in a Ser-249-dependent manner. Moreover, a reporter with the SV40 minimal promoter was inhibited by GAL4-Smad7, and this effect was also dependent on Ser-249 phosphorylation. The amplitude of effects on transcriptional regulation was dependent on cell type. Our results suggest that phosphorylation of Smad7, unlike phosphorylation of the receptor-regulated Smads, does not regulate TGF-beta signaling but rather affects TGF-beta-independent effects of Smad7 on transcriptional regulation.