Identification of two transcripts of canine, feline, and porcine interleukin-1 alpha

Interleukin-1 receptor antagonist expression in the equine endometrium during the peri-implantation period

To identify factors involved in the establishment of pregnancy in the mare, endometrium was collected from day 13 (day 0=day of ovulation) cyclic and day 13, 19, and 25 pregnant animals. From initial cDNA subtraction studies, interleukin-1 receptor antagonist (IL-1RN) mRNA was found as a candidate molecule expressed uniquely in the pregnant endometrium. Expression of IL-1RN mRNA was markedly increased in day 19 and 25 gravid endometrium. In situ hybridization analysis revealed that IL-1RN mRNA was localized to the glandular epithelium. Interleukin-1 receptor antagonist (IL-1RN) protein was found in the extracts of day 25 gravid endometrium and was immunochemically localized to the glandular epithelium/luminal cavity of the pregnant uterus. High concentrations of estradiol-17beta (E(2)) were detected in day 25 conceptuses. Concentrations of E(2) were higher in the gravid endometrial portion than in other endometrial regions. On the other hand, progesterone concentrations did not differ among endometrial samples analyzed. Furthermore, the expression of IL-1RN mRNA was up-regulated in endometrium culture samples treated with 10 ng/mL E(2) and 10 ng/mL progesterone. In the analysis of related gene expression, increased amounts of IL-1alpha and IL-6 mRNA were also found in the day 25 gravid endometrium; however, these expressions in endometrial culture samples were not up-regulated by the steroid treatment. These results indicate that expression of IL-1RN in the endometrium is likely regulated by E(2) and progesterone and suggest that IL-1RN regulates the degree of IL-1 signal transduction and thereby plays an important role in the establishment of equine pregnancy.

Increased expression of interleukin-1beta and its novel splice variant in canine hearts with volume overload

Volume overload frequently caused in dogs by chronic degenerative valvular disease (CDVD), eventually leads to cardiac failure. Experimental and clinical evidences demonstrate that increased interleukin-1beta serum level in patients with heart insufficiency correlates with the severity of failure irrespective of its etiology. Very little is known about the IL-1beta expression in failing vs. non-failing myocardium. IL-1beta transcript level was determined in the CDVD dogs (n=17) and control animals (n=9) without cardiac insufficiency by real-time PCR. IL-1beta transcript level in failing hearts was higher than in the control. In both groups the highest IL-1beta level was detected in the left ventricles. Although IL-1beta is a major pro-inflammatory cytokine most of the CDVD dogs displayed no inflammatory infiltrates into the myocardium. Massive fibrosis was observed in the control group, unlike the failing hearts, in which cardiomyocyte hypertrophy and atrophy dominated. The alternative IL-1beta transcript identified here (IL-1betasv1) was significantly elevated in the failing myocardium compared with the control group. Increased IL-1beta expression seems to be associated with mechanical heart overload. Its endogenous origin, and certain histopathological findings attributed to IL-1beta indicate its importance in cardiac hypertrophy and failure. The lack of some typical IL-1beta actions, i.e. inflammatory, pyrogenic and fibrotic, may suggest a different role of this cytokine in myocardium. It appears that the canine IL-1beta gene can be transcribed in two ways in heart tissue, with the IL-1betasv1 form present mainly in failing hearts.

Constitutive repression of interleukin-1alpha in endothelial cells

Activation of complement stimulates inflammation and provides an initial vigorous defense against infection. Insertion of the membrane attack complex in cell membranes of vascular endothelial cells induces changes in cell differentiation that promote coagulation, thrombosis, inflammation, and immunity. These changes are mediated by production of interleukin (IL)-1alpha by endothelial cells, which acts locally on endothelial cells to contain infection and promote healing of the affected site. In healthy tissues, however, promoting coagulation and inflammation would be dysphysiologic. Accordingly, endothelial cell activation by the membrane attack complex depends on both transcriptional regulation of IL-1alpha and availability of that cytokine to broadly modify endothelial cell physiology. Here, we report that the IL-1alpha gene contains a suppressor sequence that cooperates with histone modification to regulate production of IL-1alpha by endothelial cells. The suppressor sequence binds C/EBP (CCAAT enhancer-binding protein) family DNA-binding proteins isolated from the nucleus of quiescent endothelial cells. These results suggest constitutive suppression of IL-1alpha maintains quiescence of endothelium and that terminal complement complexes remove that suppression, allowing IL-1alpha transcription and, ultimately, activation of endothelium to proceed.

Comparison of the human and canine cytokines IL-1(alpha/beta) and TNF-alpha to orthologous other mammalians

The cytokines interleukin-1 (IL-1alpha and IL-1beta) and the tumor necrosis factor-alpha (TNF-alpha) both play a major role in the initiation and regulation of inflammation and immunity responses. Polymorphisms within the gene sequences of these cytokines IL-1 and TNF-alpha have been proposed to play an important role in the pathogenesis of certain diseases. Affecting nearly every organ, various diseases, including some cancers, are described to be associated with an increased level of IL-1 and TNF-alpha proteins, for example, solid tumors, hematologic malignancies, malignant histiocytosis, autoimmune disorders, Alzheimer's disease, Parkinson's disease, sepsis, and rheumatoid arthritis. Regarding genetic backgrounds and pathways, numerous canine diseases show close similarities to their human counterparts. As a genetic model, the dog could be used to unravel the genetic mechanisms, for example, in particular the predispositions, the development, and progression of cancer and metabolic diseases. The identity comparison of gene and protein sequences of different species could be used to elucidate the structure and function of the genes and proteins by identifying the evolutionary conserved regions and domains. Herein we analyzed in detail the mRNA and protein structures and identities of the present known mammalian (human, canine, murine, rat, ovine, equine, feline, porcine, and bovine) TNF-alpha, IL-1alpha, and IL-1beta mRNAs and proteins. Additionally, based on the canine genome sequence, we derived in silico the complete mRNA structures of the IL-1alpha and IL-1beta mRNAs.

On the sequential determinants of calpain cleavage

The structural clues of substrate recognition by calpain are incompletely understood. In this study, 106 cleavage sites in substrate proteins compiled from the literature have been analyzed to dissect the signal for calpain cleavage and also to enable the design of an ideal calpain substrate and interfere with calpain action via site-directed mutagenesis. In general, our data underline the importance of the primary structure of the substrate around the scissile bond in the recognition process. Significant amino acid preferences were found to extend over 11 residues around the scissile bond, from P(4) to P(7)'. In compliance with earlier data, preferred residues in the P(2) position are Leu, Thr, and Val, and in P(1) Lys, Tyr, and Arg. In position P(1) ', small hydrophilic residues, Ser and to a lesser extent Thr and Ala, occur most often. Pro dominates the region flanking the P(2)-P(1)' segment, i.e. positions P(3) and P(2)'-P(4)'; most notable is its occurrence 5.59 times above chance in P(3)'. Intriguingly, the segment C-terminal to the cleavage site resembles the consensus inhibitory region of calpastatin, the specific inhibitor of the enzyme. Further, the position of the scissile bond correlates with certain sequential attributes, such as secondary structure and PEST score, which, along with the amino acid preferences, suggests that calpain cleaves within rather disordered segments of proteins. The amino acid preferences were confirmed by site-directed mutagenesis of the autolysis sites of Drosophila calpain B; when amino acids at key positions were changed to less preferred ones, autolytic cleavage shifted to other, adjacent sites. Based on these preferences, a new fluorogenic calpain substrate, DABCYLTPLKSPPPSPR-EDANS, was designed and synthesized. In the case of micro- and m-calpain, this substrate is kinetically superior to commercially available ones, and it can be used for the in vivo assessment of the activity of these ubiquitous mammalian calpains.

Molecular cloning and expression of a functionally different alternative splice variant of prointerleukin-1alpha from the rat testis

We report here the characterization of an alternative splice variant of prointerleukin-1alpha (proIL-1alpha), constitutively expressed by the normal adult rat testis. In addition to the classical 32K proIL-1alpha (32proIL-1alpha) messenger RNA, the testis produced a shorter variant encoding a putative protein of 24K (24proIL-1alpha). In situ hybridization demonstrated constitutive expression of the splice transcript in the seminiferous tubules. This alternative complementary DNA lacked the fifth exon, harboring the calpain cleavage site essential for generation of mature 17K IL-1alpha. This was verified by calpain treatment, producing the expected cleavage products of recombinant 32proIL-1alpha, but not of 24proIL-1alpha. Similarly, expression in COS-7 cells demonstrated processing of 32proIL-1alpha to the mature 17K form and secretion, whereas 24proIL-1alpha remained unprocessed. Both 32proIL-1alpha and 24proIL-1alpha showed a dose-dependent stimulatory effect in a thymocyte proliferation assay, although at lower potency than mature 17K IL-1alpha. In contrast, when tested on hCG-stimulated Leydig cells in vitro, a dose-dependent inhibition of testosterone production was obtained with mature 17K IL-1alpha and at a lower potency with 32proIL-1alpha, whereas 24proIL-1alpha was inactive. In conclusion, the three IL-1 bioactive proteins described here contribute to IL-1 protein heterogeneity and may serve as constitutive paracrine mediators in the testis.