Suppression of atrial natriuretic peptide/natriuretic peptide receptor-A-mediated signaling upregulates angiotensin-II-induced collagen synthesis in adult cardiac fibroblasts

Cardiac hormone atrial natriuretic peptide (ANP) and its receptor natriuretic peptide receptor-A (NPR-A) system acts as an intrinsic negative regulator of abnormal extracellular matrix (ECM) remodeling in the heart. However, the underlying mechanism by which ANP/NPR-A system opposes the ECM remodeling in the diseased heart is not well understood. Here, we investigated the anti-fibrotic mechanism of ANP/NPR-A in fibrotic agonist Angiotensin- II (ANG II)-treated adult cardiac fibroblast (CF) cells. Normal and NPR-A-suppressed adult CF cells were treated with ANG II (10^?7 M) in the presence and absence of ANP (10^?8 M) for 24 h. Total collagen concentration, activity and expression of MMP-2 and MMP-9, and nuclear translocation of Nuclear factor-kappaB (NF-κB-p50) were studied. NPR-A-suppressed adult CF cells exhibited a more pronounced increase in collagen production, ROS generation, and NF-κB-p50 nuclear translocation as compared to adult CF cells treated with agonist alone. ANP co-treatment significantly reverses the agonist-induced above changes in normal adult CF cells, while it failed to reverse the agonist-induced collagen synthesis in the NPR-A-suppressed adult CF cells. The cGMP analog (8-bromo-cGMP) treatment significantly attenuated the agonist-induced collagen synthesis both in normal and NPR-A-suppressed adult cells. The results of this study suggest that ANP/NPR-A signaling system antagonizes the agonist-induced collagen synthesis via suppressing the activities of MMP-2, MMP-9, ROS generation, and NF-κB nuclear translocation mechanism.     

Computed spatial homology between the L12 protein of chloroplast ribosome and 1.7 A structure of Escherichia coli L12 domain

A computer-graphic model of the tertiary structure of a functional domain in an organelle ribosomal protein was generated using the amino acid sequence of chloroplast ribosomal protein L12 from spinach (Bartsch, Kimura and Subramanian, Proc. Natl. Acad. Sci. USA 79, 6871-6875, 1982) and 1.7 A resolution coordinates of the E. coli L12 C-terminal fragment crystal (Leijonmarck, Eriksson and Liljas, Nature 286, 824-826, 1980). A comparison between the model and the experimentally derived structure shows that although 40% of the primary structure of this part of the two proteins has undergone amino acid replacements, the gross spatial structure of the domain is maintained and the character of the surfaces of possible functional importance are not significantly altered.     

Endocrine response in rabbits immunized with native versus deglycosylated porcine zona pellucida antigens

Previous studies evaluating porcine zona pellucida antigens for immunocontraceptive purposes have in some cases revealed altered ovarian function in association with antibody response. This study was undertaken in an attempt to identify zona immunogens that do not cause adverse endocrine effects. To this end, we investigated the effects of highly purified preparations of native and deglycosylated pig zona pellucida antigens on ovarian function and immune response in the rabbit. Thirty female rabbits were immunized, 5 per group, with 100 micrograms each of either 1) SIZP, solubilized isolated zonae pellucidae; 2) ZP3, a purified porcine zona preparation containing the two principle glycoproteins, ZP3 alpha and ZP3 beta, endo-beta-galactosidase-digested ZP3 glycoproteins (approximately 30% deglycosylated) termed 3) ZP3 alpha/EBGD and 4) ZP3 beta/EBGD; and chemically deglycosylated ZP3 alpha and ZP3 beta (greater than or equal to 92% deglycosylated), termed 5) ZP3 alpha/DG and 6) ZP3 beta/DG. Rabbits injected with saline (n = 2) or Freund's adjuvant alone (n = 3) served as controls. Serum LH, FSH, estradiol, and progesterone were measured at 5-day intervals during seven 20-day cycles of hCG-induced pseudopregnancy over 42 wk. Anti-ZP3 titers, determined by RIA, developed in all treatment groups and correlated directly with carbohydrate content. Animals immunized with SIZP, ZP3, and ZP3 beta/EBGD showed a significant elevation of LH and FSH and a significant decline of peak progesterone levels by the fourth pseudopregnancy cycle. In contrast, animals immunized with ZP3 alpha/EBGD, ZP3 alpha/DG, and ZP3 beta/DG showed no significant elevations of gonadotropins and continued to display cyclic progesterone secretion in response to hCG.(ABSTRACT TRUNCATED AT 250 WORDS)     

The crystal at 5.5A resolution of an acid-protease from Rhizopus chinensis.

An electron density map for the pepsin-like enzyme from Rhizopus chinensis has been calculated at 5.5Å resolution. The molecular boundary has been defined and certain secondary structural details have been inferred. The molecule is bilobal and has a large cleft in which several inhibitors have been observed to bind.