Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of the gene for the iron transport protein transferrin was found to be altered in preneoplastic and neoplastic lesions induced in the rat liver by N-nitrosomorpholine. The total RNA of ten hepatocellular carcinomas (HCC) was investigated by Northern blot analysis using a cDNA-probe comprising 150 bp of the 3' region and compared with the total hepatic RNA in untreated rats. Seven hepatocellular carcinomas showed slight or pronounced reduction in transferrin expression. In situ hybridization of two additional hepatocellular carcinomas revealed marked reduction in the mRNA level for the transferrin gene compared with the surrounding tissue. In contrast, the majority of early preneoplastic lesions storing excess glycogen and tigroid cell foci expressed increased levels of transferrin mRNA. The loss of glycogen in mixed cell foci, which represent a later stage of hepatocarcinogenesis, was usually accompanied by a decrease in transferrin mRNA suggesting a close relationship between this change in gene expression and cellular dedifferentiation emerging during hepatocarcinogenesis.
Virchows Arch B Cell Pathol Incl Mol Pathol 1992
PMID:Altered transferrin gene expression in preneoplastic and neoplastic liver lesions induced in rats with N-nitrosomorpholine. 135 98

Chemotactic and mitogenic activities of granulosa cells in developing follicles were studied. Immature rats were subcutaneously injected with 20 IU of pregnant mare's serum gonadotrophin and killed at various intervals after injection. The ovaries were removed and granulosa cells were isolated and cultured in a serum-free medium supplemented with insulin, transferrin and hydrocortisone. Chemotactic and mitogenic activities in the conditioned medium were determined. Our results demonstrated that in addition to mitogenic activity, chemotactic activity was also expressed in the conditioned medium of granulosa cells. Both activities increased with the maturity of follicles. A gel filtration analysis revealed that there were two peaks showing both mitogenic and chemotactic activities with a molecular size smaller than 5000. These peaks had various sensitivities to heat and trypsin treatment. In addition, the active component of both peaks was organic solvent-extractable. A thin-layer chromatography analysis indicated that the lipid component was not prostaglandin, estradiol or hydrocortisone.
Mol Cell Endocrinol 1992 Mar
PMID:Chemotactic and mitogenic activities of granulosa cells in developing follicles. 137

In our previous paper (Chen et al. (1991) J. Biol. Chem. 266, 4081-4087) we reported the preparation and characterization of recombinant human choriogonadotropin beta subunit (hCG beta) using the baculovirus-insect cell expression system. The rhCG beta was found to contain high mannose type N-linked carbohydrates and 3-4 serine-linked disaccharide chains. Despite the carbohydrate structural variation, the rhCG beta was similar to hCG beta in in vitro immunological and biological properties. In order to evaluate its in vivo immunological properties, rabbit antiserum against rhCG beta was produced. The antiserum was found to be almost identical to anti-hCG beta in binding to hCG beta as well as in its crossreactivity with human lutropin (hLH), hCG and human follitropin (hFSH) as indicated by radioimmunoassays using 125I-hCG beta as a tracer. Further characterization of the anti-rhCG beta antiserum revealed that there are three types of antibodies in terms of antigenic specificity present in the anti-rhCG beta antisera pool as shown by dot blot and radioimmunoassays. The carbohydrate-specific antibodies were separated by affinity chromatography using an ovalbumin-glycopeptide-Sepharose column. The antibodies held on the ovalbumin affinity adsorbent were specific for the high mannose type carbohydrates such as those present in rhCG beta, rhCG and thyroglobulin and failed to react with transferrin, alpha 1-acid glycoprotein and hCG alpha, all containing complex type carbohydrates. This was further supported by the fact that the recombinant unglycosylated hCG or periodate oxidized rhCG beta also did not show any reactivity with the carbohydrate specific antibodies. Two types of peptide epitopes seemed to be present in rhCG beta since when the flowthrough fraction from the ovalbumin-glycopeptide-affinity column was passed through the hCG beta-Sepharose column, the antibodies in the flowthrough from the latter column were specific to the unique antigenic determinants present only in the rhCG beta and not in hCG beta. The eluate from the hCG beta-Sepharose column contained the third type of antibodies, being the predominant ones, directed to the common epitopes between rhCG beta and hCG beta. The high mannose type specific antibodies are potentially useful in differentiating between the high mannose and complex type of N-linked carbohydrates present in a glycoprotein. Also, the antibody could provide an effective reagent in studying the intracellular processing of the N-linked oligosaccharides.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Cell Endocrinol 1992 Jul
PMID:Polyclonal antibodies against the polypeptide and carbohydrate epitopes of recombinant human choriogonadotropin beta-subunit. 138 Sep 28

In previous histoimmunochemical studies we reported that transferrin (TF) and insulin-like growth factor I (IGF-I) are present in the cytoplasm of the Sertoli cells of the adult human testis. Receptors for TF were found mainly in adluminal germ cells and type I receptors for IGF-I both in Sertoli and germ cells. Using electron microscopy, evidence of transfer of both TF and IGF-I from the Sertoli to the germ cells through a receptor-mediated endocytosis mechanism was also found. In this paper we report the results of the histoimmunochemical localization of alpha inhibin in the human fetal, prepubertal and adult testis. In 8- to 14-week-old fetal testes a positive immunostaining was found mainly in the interstitial cells, whereas no staining was found in the germ cords. In the prepubertal testis the immunostaining was present in the Sertoli cells but not in the interstitial cells. In the adult human testis the immunostaining was present not only in the Sertoli cells but also in the spermatocytes and in several Leydig cells. Using electron microscopy and immunogold labeling the presence of alpha inhibin immunoreactivity was found in the rough endoplasmic reticulum and in the Golgi cisternae of both Sertoli and Leydig cells. Moreover we found evidence of transfer of alpha inhibin from the Sertoli to the germ cells through receptor-mediated endocytosis.
J Steroid Biochem Mol Biol 1992 Oct
PMID:Sertoli-germ cells interactions in the human testis. 139 Feb 91

The N-terminal lobe of recombinant human serum transferrin (residues 1 to 337) has been crystallized in a form suitable for high-resolution three-dimensional X-ray crystallographic analyses. Crystals are of the orthorhombic space group P2(1)2(1)2(1), with unit cell dimensions of a = 44.9 A, b = 57.0 A and c = 135.9 A, and diffract to beyond 2 A resolution. Further studies show that isomorphous crystals of specifically designed mutants of this protein can also be grown. Structural studies of both recombinant and mutant protein forms will provide a basis for understanding the mechanism by which human serum transferrin functions.
J Mol Biol 1992 Sep 20
PMID:Preliminary crystallographic analyses of the N-terminal lobe of recombinant human serum transferrin. 140 72

Non-heme iron is essential for the asexual growth of the human malaria parasite Plasmodium falciparum in mature erythrocytes. Utilization of iron bound to serum transferrin by the parasitized cells has been postulated, but direct evidence for its specific delivery has not been reported. Here we demonstrate that normal levels of transferrin in human serum are not required for intraerythrocytic P. falciparum growth: culture medium immunodepleted 500-1000 fold in human transferrin was capable of supporting parasitemias and rates of invasion comparable to those observed in non-depleted medium. 55Fe bound to transferrin was not taken up by infected cells. A transferrin-independent non-heme iron uptake activity was, however, detected in both infected and uninfected erythrocytes when iron was presented to the cells as 55Fe-NTA or 55Fe-citrate. Although the uptake activity was not parasite specific, the radiolabel was found in association with parasites mechanically released from the infected erythrocytes, indicating that it is delivered to the intracellular organism. Evidence is presented that the transferrin-independent iron uptake activity is time-, temperature- and concentration-dependent, but apparently not energy-dependent.
Mol Biochem Parasitol 1992 Oct
PMID:A transferrin-independent iron uptake activity in Plasmodium falciparum-infected and uninfected erythrocytes. 143 78

Testicular peritubular cells produce a paracrine factor, PModS, under androgen control that modulates Sertoli cell functions that are essential for the process of spermatogenesis. PModS has a more dramatic effect on Sertoli cell differentiated functions in vitro than any regulatory agent previously shown to influence the cell, including FSH. Investigation of the actions of PModS on a molecular level have used transferrin expression as a marker of Sertoli cell differentiation. PModS was found to stimulate transferrin gene expression while having no effect on transferrin mRNA stability. The ability of PModS to elevate transferrin mRNA levels was inhibited by cycloheximide. Therefore, the actions of PModS require ongoing protein synthesis and appear to be indirectly mediated through trans-acting early event genes. PModS was found to dramatically increase mRNA levels for c-fos, but had no effect on c-jun mRNA levels. The c-fos mRNA levels increased transiently within a few minutes to a maximal level of stimulation at 1 h and returned to basal levels within 6 h. The rise in c-fos mRNA preceded the elevation in transferrin mRNA, which started to increase at 2 h to a maximum level between 6-12 h that was maintained at high levels for several days in cell culture. Treatment of Sertoli cells with an antisense c-fos oligonucleotide was found to inhibit the actions of PModS on transferrin expression. Combined results support the hypothesis that PModS acts indirectly through transcription factors (e.g. c-fos) to induce Sertoli cell differentiated functions (e.g. transferrin expression). Therefore, PModS appears to act as a differentiation-type factor to promote and maintain optimal Sertoli cell function.
Mol Endocrinol 1992 Dec
PMID:Regulation of Sertoli cell differentiation by the testicular paracrine factor PModS: potential role of immediate-early genes. 149 88

We have established a monolayer culture system for human fallopian tube epithelial cells. The cells were isolated from tubes using collagenase digestion, and were cultured in Ham's F-10 supplemented with 15% fetal calf serum. The epithelial cells derived from culture were characterized using immunocytochemical staining and electron microscopy. These cells were stained with antikeratin and anti-epithelial membrane antigen, but showed no staining after treatment with antivimentin. Electron microscopy showed many microvilli on the cell surface and tight junctions or desmosomes at areas of cell-cell contact. Cell proliferation was enhanced by epidermal growth factor, but not by fibroblast growth factor, insulin, transferrin, estradiol-17 beta, or progesterone. The 2-cell ICR mouse pre-embryos were co-cultured for 4 days with tubal epithelial cells (A) (n = 98), in cell-conditioned medium (B) (n = 83), or in medium alone (C) (n = 72). During the first 24 h in culture, for groups A and B, the rates of cleavage to the 4-cell stage were 90.9% and 81.9%, respectively. Cleavage rates in these two groups were significantly higher (P = 0.0012, P less than 0.00001) than in group C (56.9%). After 72 h in culture, the rates of development to the blastocyst stage were significantly higher for groups A and B compared to group C (89.6% and 73.5% vs. 54.5%, P less than 0.00001, P = 0.0002). These results suggest that factor(s) from tubal epithelial cells may facilitate the development of mouse pre-embryos throughout the pre-implantation stages.
Mol Reprod Dev 1992 Jul
PMID:Primary culture of human fallopian tube epithelial cells and co-culture of early mouse pre-embryos. 149 73

Four human lung adenocarcinoma cell lines were established in serum-free F12 medium supplemented with insulin, transferrin, hydrocortisone, cholera toxin, selenium, epidermal growth factor, bovine hypothalamic extract, and retinoic acid. Histochemical analyses with periodic acid-Schiff with and without diastase treatment (PAS-D technique) and immunocytochemistry with a mucin-specific monoclonal antibody demonstrated that three of the cell lines (CL2, CL3, and NCL2) were capable of mucin production. Biochemical characterizations of mucin produced by adenocarcinoma cells were focused on one of the cell lines, CL2 cells, which showed the most prominent reactivity with mucin-specific monoclonal antibody. Biochemical analysis using the mucin precursors [3H]glucosamine and [14C]serine indicated that CL2 cells can synthesize high-molecular-weight (M(r) greater than 200 kD) glycoprotein molecules that can be immunoprecipitated by this mucin-specific monoclonal antibody. The high-molecular-weight glycoproteins isolated from CL2 cells specifically reacted with mucin-specific monoclonal antibody by Western blot analysis, and composition analyses showed high levels of serine and threonine and a low level of aromatic amino acids, which are similar to human airway mucin. These observations suggest that lung adenocarcinoma CL2 cells cultured in this serum-free medium can retain function of airway mucin synthesis. Cell kinetic studies of these four cell lines showed that the cell line (CL1) without the mucin differentiation had a higher proliferative index and a shorter population doubling time as compared with the other three cell lines (CL2, CL3, and NCL2) with mucin differentiation. Examination of the retinoblastoma protein expressions in these adenocarcinoma cell lines revealed a phosphorylated pattern that correlated inversely with the mucin synthesis status of these cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1992 Aug
PMID:Characterization of the mucin differentiation in human lung adenocarcinoma cell lines. 149 5

Estrogen destabilizes transferrin mRNA in male Xenopus liver in the same manner as observed for albumin and gamma-fibrinogen. The present study examined estrogen regulation of transferrin gene expression in female Xenopus liver and oviduct. In female Xenopus liver estrogen causes the same enhanced degradation of transferrin mRNA from the cytoplasm as seen in males. In contrast, transferrin is induced 3- to 4-fold in both oviduct nuclear and cytoplasmic RNA. The similar increase in transferrin RNA in both preparations suggests a transcriptional mechanism is responsible for this stimulation. Therefore, transferrin expression is differentially regulated in these tissues by the same hormone. Previous experiments showed that Xenopus serum albumin mRNA has a very short (17 residue) poly(A) tail that may play a role in its hormone-regulated instability. Transferrin mRNA has a similarly short poly(A) tail in liver of both male and female Xenopus. Estrogen has no effect on transferrin polyadenylation in liver. Similarly short poly(A) is found on transferrin mRNA from estrogen-deprived oviducts in explant culture. However, addition of estradiol to the medium results in the appearance of a 50-200 nucleotide poly(A) concurrent with induction. Therefore, transferrin mRNA is differentially polyadenylated in Xenopus liver and oviduct. In the latter tissue polyadenylation is under hormonal control.
J Steroid Biochem Mol Biol 1992 Aug
PMID:Differential regulation and polyadenylation of transferrin mRNA in Xenopus liver and oviduct. 150 5


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