Previously characterized soluble guanylyl cyclases form ␣- heterodimers that can be activated by the gaseous messenger, nitric oxide. In mammals, four subunits have been cloned, named ␣1, ␣2, 1, and 2. We have identified a novel soluble guanylyl cyclase isoform from the nervous system of the insect Manduca sexta that we have named M. sexta guanylyl cyclase 3 (MsGC-3). It is most closely related to the mammalian  subunits but has several features that distinguish it from previously identified soluble cyclases. Most importantly, MsGC-3 does not need to form heterodimers to form an active enzyme because guanylyl cyclase activity can be measured when it is expressed alone in COS-7 cells. Moreover, this activity is only weakly enhanced in the presence of the nitric oxide donor, sodium nitroprusside. Several of the amino acids in rat 1 subunits, previously identified as being important in heme binding or necessary for nitric oxide activation, are substituted with nonsimilar amino acids in MsGC-3. There are also an additional 315 amino acids C-terminal to the catalytic domain of MsGC-3 that have no sequence similarity to any known protein. Northern blot analysis shows that MsGC-3 is primarily expressed in the nervous system of Manduca.The intracellular messenger cGMP mediates a wide variety of cellular and physiological processes. It functions as the primary messenger in visual transduction (1, 2), is an important regulator in vascular smooth muscle and kidney function (3, 4), and has been implicated in a number of forms of neuronal plasticity (5-7).The enzymes that regulate the synthesis of cGMP fall into two major classes: the cytoplasmically localized, soluble guanylyl cyclases and the membrane associated, receptor guanylyl cyclases (4). Soluble guanylyl cyclases are obligate heterodimers composed of an ␣ and a  subunit. Two ␣ (␣1 and ␣2) and two  (1 and 2) subunits have been cloned from mammalian tissues (8 -13). The active heterodimer requires and binds heme as a prosthetic group and can be potently activated by the gaseous messenger, nitric oxide (NO) 1 (14). The soluble cyclases are found in the cytosol of cells, although the mammalian 2 subunit has a consensus isoprenylation site, suggesting that it might be associated with membranes. The receptor guanylyl cyclases, by contrast, are integral membrane proteins with transmembrane and extracellular domains (4).We have been using the insect Manduca sexta as a model system to study cGMP regulation and have previously shown that a neuropeptide, eclosion hormone, is a potent stimulator of cGMP levels in the central nervous system (15). Biochemical characterization of the eclosion hormone-stimulated cGMP increase suggested that eclosion hormone might activate a NOinsensitive, soluble guanylyl cyclase (15-18). In an attempt to identify the pathway for eclosion hormone-stimulated cGMP levels, we used reverse transcription-polymerase chain reaction (RT-PCR) to identify guanylyl cyclases from Manduca nervous tissue. This approach has yielded a number of dif...
Abstract. Background:The association of DLG5 R30Q with IBD has been replicated in several populations, but is not statistically significant in others. We studied the incidence of DLG5 alleles in a population of IBD patients from Pennsylvania. Methods: DLG5 R30Q (rs1248696) and G1066G (rs1248634) were analyzed with PCR-based RFLP methods in a total of 521 subjects, that included 105 individuals with IBD and 139 without IBD from a familial IBD registry, 107 with sporadic IBD, and 170 unrelated healthy controls. R30Q was further analyzed with SNPlex TM Genotyping System in 473 samples. Results: RFLP genotyping data showed that, DLG5 R30Q was significantly associated with IBD overall (p = 0.006), and separately with CD (p = 0.009) and UC (p = 0.024). The association of R30Q with IBD was entirely due to a male-associated effect (male vs female p = 0.015 vs 0.241 (IBD), p = 0.024 vs 0.190 (CD), and p = 0.019 vs 0.575 (UC)). The frequency of the A allele carriage was elevated in both affected and unaffected members in the familial IBD cohort compared to healthy controls (p = 0.037). In the family pedigrees, we observed differences in the expression of IBD in individuals carrying the A allele between families. Conclusions: In the studied population, DLG5 R30Q was associated with all forms of IBD. An elevated presence of the R30Q variant was observed in all members of a familial IBD registry. This association of the R30Q variant with IBD was male-specific.
We replicated the association of IL23R R381Q with CD but not UC, and we observed an association of L310P with UC, but not CD, in a central Pennsylvania population. Further analysis of the distribution of IL23R variants revealed that these effects were largely female-specific. The results suggest that IL23R R381Q confers protection against CD and that L310P confers protection against UC in females.
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