نبذة مختصرة : The aim of the present study was to gain a better insight into the role of interleukin-1 alpha (IL-1 alpha) in testicular physiology. In testis, IL-1alpha acts as a paracrine mediator involved in the regulation of testicular functions. Bioactive IL-1 alpha isolated and characterized from adult rat testis, showed the presence of several distinct protein species, with a size range of 17-40 kDa and charge heterogeneity. The present study was undertaken to clarify the molecular heterogeneity and to characterize different isoforms of IL-1alpha in rat testis and to study the processing, secretion, regulation and function of these isoforms. The physicochemical characterization revealed that testicular IL-1 alpha is similar to IL-1 alpha from activated macrophages. IL-1 bioactivity of crude testis protein was completely neutralized by IL-1 alpha antiserum, IL-1 receptor antagonist and soluble type 1 IL-1 receptor. Three isoforms of IL-1 alpha proteins with molecular sizes of 45, 31 and 17 kDa and at charges of pH 5.7 and 6.0 are found in the testis. All three forms are secreted into the interstitial compartment and tubular lumen. Molecular characterization revealed that heterogeneity also existed at the transcriptional level and a novel splice variant was found and named as 24proIL-1 alpha. It lacked exon 5, which harbors the cleavage site of the processing enzyme calpain. Expression of these isoforms in COS. cells and in vitro calpain cleavage assay of recombinant protein expressed in E. coli confirmed that 32proI1l-1 alpha was processed to produce 17 kDa whereas 24proIL-1 alpha was resistant to cleavage. Both forms were bioactive in thymocyte proliferation IL-1 bioassay. However, these isoforms showed differential activity on human chorionic gonadotropin (hCG)-induced Leydig cell steroidogenesis. 32proIL-1 alpha was inhibitory and 24proIL-1 alpha showed no effect. On analysis of mechanism of action, 24proIL-1alpha showed weak but significant stimulation of hCG-induced steroidogenesis in Leydig cells from 40- day-old ...
Relation: I. Gustafsson K, Sultana T, Zetterstrom CK, Setchell BP, Siddiqui A, Weber G, Soder O (2002). Production and secretion of interleukin-1alpha proteins by rat testis. Biochem Biophys Res Commun. 297(3): 492-7. ::pmid::12270120; II. Sultana T, Svechnikov K, Weber G, Soder O (2000). Molecular cloning and expression of a functionally different alternative splice variant of prointerleukin-1alpha from the rat testis. Endocrinology. 141(12): 4413-8. ::pmid::11108249; III. Svechnikov KV, Sultana T, Soder O (2001). Age-dependent stimulation of Leydig cell steroidogenesis by interleukin-1 isoforms. Mol Cell Endocrinol. 182(2): 193-201. ::pmid::11514054; IV. Sultana T, Wahab-Wahlgren A, Assmus M, Parvinen M, Weber G, Soder O (2002). Expression and regulation of proIL-1alpha processing enzyme, calpain I and II in rat testis. International Journal of Andrology. 25: 1-10.; V. Sultana T, Al-Shakarchi I, Tham E, Weber G, Soder O (2002). Subcellular localization and cell activating properties of testicular interleukin-1alpha isoforms. [Manuscript]; 91-7349-389-9; 20021206sult; http://hdl.handle.net/10616/39610
Processing Request
No Comments.