Immunohistochemical expression of heparanase isoforms and syndecan-1 proteins in colorectal adenomas
EUROPEAN JOURNAL OF HISTOCHEMISTRY
Authors: Waisberg, J.; Theodoro, T. R.; Matos, L. L.; Orlandi, F. B.; Serrano, R. L.; Saba, G. T.; Pinhal, M. A. S.
Abstract
The proteoglycan syndecan-1 and the endoglucuronidases heparanase-1 and heparanase-2 are involved in molecular pathways that deregulate cell adhesion during carcinogenesis. Few studies have examined the expression of syndecan-1. heparanase-1 and mainly heparanase-2 proteins in non-neoplastic and neoplastic human colorectal adenoma tissues. The aim of this study was to analyze the correlation among the heparanase isoforms and the syndecan-1 proteins through immunohistochemical expression in the tissue of colorectal adenomas. Primary antihuman polyclonal anti-HPSE and anti-HPSE2 antibodies and primary anti-human monoclonal anti-SDC1 antibody were used in the immunohistochemical study. The expressions of heparanase-1 and heparanase-2 proteins were determined in tissue samples from 65 colorectal adenomas; the expression of syndecan-1 protein was obtained from 39 (60%) patients. The histological type of adenoma was tubular in 44 (67.7%) patients and tubular-vilIons in 21 (323 A); there were no villous adenomas. The polyps were <1.0 cm in size in 54 (83.1%) patients and >= 1.0 cm in 11 (16.9%). The images were quantified by digital counter with a computer program for this purpose. The expression index represented the relationship between the intensity expression and the percentage of positively stained cells. The results showed that the average of heparanase-1. heparanase-2 and syndecan-1 expression index was 73.29 o.u./mu m(2), 93.34 o.u./mu m(2), and 55.29 o.u./mu m(2). respectively. The correlation between the heparanase-1 and syndecan-1 expression index was positive (R=0.034) and significant (P=0.035). There was a negative (R=-0.384) and significant (P=0.016) correlation between the expression index of heparanase-1 and heparanase-2. A negative (R=-0421) and significant (P=0.008) correlation between the expression index of heparanase-2 and syndecan-1 was found. We concluded that in colorectal adenomas, the heparanase-1 does not participate in syndecan-1 degradation; the heparanase-2 does not stimulate syndecan-1 degradation by the action of heparanase-1. and the heparanase-2 may be involved in the modulation of the heparanase-1 activity.
Crystal Structure of the COMPASS H3K4 Methyltransferase Catalytic Module
CELL
Authors: Hsu, Peter L.; Li, Heng; Lau, Ho-Tak; Leonen, Calvin; Dhall, Abhinav; Ong, Shao-En; Chatterjee, Champak; Zheng, Ning
Abstract
The SET1/MLL family of histone methyltransferases is conserved in eukaryotes and regulates transcription by catalyzing histone H3K4 mono-, di-, and tri-methylation. These enzymes form a common five-subunit catalytic core whose assembly is critical for their basal and regulated enzymatic activities through unknown mechanisms. Here, we present the crystal structure of the intact yeast COMPASS histone methyltransferase catalytic module consisting of Swd1, Swd3, Bre2, Sdc1, and Set1. The complex is organized by Swd1, whose conserved C-terminal tail not only nucleates Swd3 and a Bre2-Sdc1 subcomplex, but also joins Set1 to construct a regulatory pocket next to the catalytic site. This inter-subunit pocket is targeted by a previously unrecognized enzyme-modulating motif in Swd3 and features a doorstop-style mechanism dictating substrate selectivity among SET1/MLL family members. By spatially mapping the functional components of COMPASS, our results provide a structural framework for understanding the multifaceted functions and regulation of the H3K4 methyltransferase family.