Immunohistochemical localization of calbindins (28K and 9K) in the tissues of the baboon Papio ursinus

Expression of Calbindin-D28K in Sporadic Nephroblastomas of the Chicken

Calbindin-D28K (Ca-D28K) is a calcium-binding protein. In the kidney, Ca-D28K is present in the distal nephron, but not in the proximal nephron. This site-specific distribution in the kidney indicates that Ca-D28K is a potential marker for the differentiation of the distal nephron. In this study, we have examined the expression of Ca-D28K in 25 sporadic cases of chicken nephroblastomas. All cases of nephroblastomas were composed of atypical tubular structures, blastemal cells, and fibrous stroma in varying degrees of differentiation. Immunohistochemically in all nephroblastoma specimens, Ca-D28K was expressed in the epithelial cells of the subsets of tubular structures, but not in the blastema or the stroma. These results suggested that the tubuli in the nephroblastomas are able to differentiate into the phenotype of distal nephrons. Furthermore, Ca-D28K might develop as a novel diagnostic marker for nephroblastomas because this molecule is reported to be completely negative in other renal tumors, including renal cell carcinoma, chromophobe carcinomas, and oncocytoma.

Endometrial expression of calbindin (CaBP)-d28k but not CaBP-d9k in primates implies evolutionary changes and functional redundancy of calbindins at implantation

The endometrium is hostile to embryo implantation except during the ‘window of receptivity’. A change in endometrial gene expression is required for the development of receptivity. Calbindin-d9k (CaBP-d9k) and calbindin-d28k (CaBP-d28k) are proteins possessing EF-hand motifs which have high affinity for Ca2+ions. Previously, it has been demonstrated that, in mouse endometrium, the expression of both calbindins is highly regulated during implantation and that both proteins play critical but functionally redundant roles at implantation. This study was the first to determine the expression of these two calbindins in the human and rhesus monkey endometrium. Initial RT-PCR analysis demonstrated that CaBP-d28k but not CaBP-d9k mRNA expression is detectable in the endometrium of both species. Western blot analysis confirmed the presence of immuno-reactive CaBP-d28k protein in the primate endometrium. Furthermore, the endometrial expression pattern of CaBP-d28k mRNA and protein was examined by Northern blot analysis and immunohistochemistry respectively in both species across the menstrual cycle and during early pregnancy. Semi-quantitative statistical analysis of the immunohistochemistry results revealed that, in the human, CaBP-d28k protein expression was maximal in luminal and glandular epithelium during the mid-secretory phase, coinciding with the time when the endometrium is receptive to embryo implantation. Expression in rhesus monkey showed a similar trend. These results suggest that, in the primate endometrium, only CaBP-d28k is expressed and that the specific regulation of this calbindin is potentially important for the establishment of uterine receptivity.

Prognostic implications of calbindin-D28k expression in lung cancer: analysis of 452 cases

Calbindin D28k (Ca-D28k) acts as a buffering system to maintain cellular calcium homeostasis and is thought to play a role in inhibiting apoptosis. The goals of this study were to assess CA-D28k expression in lung carcinomas and to correlate these results with patient survival. A total of 452 lung carcinomas were immunostained with a monoclonal antibody specific for Ca-D28K using an avidin-biotin peroxidase technique. The number of cells with nuclear staining was graded semiquantitatively into one of five groups: 0, fewer than 10%, 10 to 25%, more than 25 to 50%, more than 50 to 75%, and more than 75%. Results were correlated with patient survival using Kaplan-Meier survival curves. A total of 335 of 452 (74%) lung carcinomas were positive for Ca-D28k. There was no statistically significant difference in the prevalence of Ca-D28k expression in tumors of different histologic type. Kaplan-Meier survival analysis revealed that for patients with adenocarcinoma, those with Ca-D28k-positive tumors had a better overall survival than patients with Ca-D28k-negative tumors (P = .036). This difference was also significant for patients with Stages I and II adenocarcinomas (P = .033). No statistically significant difference in prognosis was observed for patients with Stages III and IV adenocarcinomas or for patients with other lung carcinoma types of varying stage. Ca-D28k is commonly expressed in lung carcinomas of all histologic types. For patients with localized adenocarcinoma of the lung, Ca-D28k expression correlated with improved survival. No correlation between Ca-D28k expression and patient survival was found for disseminated adenocarcinoma and for other histologic types of lung carcinoma.

Calbindin-D28k gene expression in the developing mouse kidney

Calbindin-D28k appears in the metanephric kidney during embryogenesis. We studied the temporal appearance and spatial distribution of calbindin-D28k mRNA in the developing kidneys of 12-day fetal through 21-day postnatal mice by in situ hybridization. 35S-UTP-labeled antisense (cRNA) probe to calbindin-D28k mRNA hybridized to the ureteric buds of 12-day embryos, whereas adjacent metanephrogenic tissue was unlabeled. By embryonic day 13, Y-shaped bodies of "advancing" ureteric buds were labeled intensely. In 16-day embryos, ampullae of ureteric buds were located immediately beneath the renal capsule and labeled strongly, in contrast to metanephric tubules and S-shaped bodies. The former were unlabeled and the latter were labeled only at points of contact with the ampullae. Subsequently, the ampullae of the metanephric ureteric buds hybridized with the cRNA probe, and from the 18th embryonic to the 21st postnatal day, this labeling was intense. The cRNA probe did not hybridize with the renal vesicles, proximal tubules, or tubular segments of Henle's loop derived from nephrogenic blastema, but it did label distal nephron segments. By the 21st postnatal day, collecting ducts and ureter no longer were labeled. In conclusion, calbindin-D28k mRNA is present in the developing mouse kidney, and its distribution during nephrogenesis is identical to that of calbindin-D28k per se. Collectively, these findings show that the calbindin-D28k gene is transcribed and its message is translated by the cells of the ureteric bud during the initial stage of renal morphogenesis.