Biomedical subjects

U Pihlgren

Publications and source records attributed to U Pihlgren.

5 recordsLinked to original sources

PubMed2000

Tissue distribution of bovine cystatin C analysed by in situ hybridisation.

Cysteine proteinase inhibitors of the cystatin superfamily have been identified in many living organisms. However, knowledge of the tissue distribution of such inhibitors is limited. To elucidate this distribution in mammals, we have investigated the expression of the gene for cystatin C, belonging to cystatin family II, in several bovine tissues. In situ hybridisation with a digoxigenin-labelled cRNA probe demonstrated a high concentration of bovine cystatin C mRNA in the secretory epithelial cells of the choroid plexus, and also intense staining in cells of lymphoid tissue and in Sertoli cells. Cystatin C mRNA was also present in scattered neurons and glial cells throughout the cerebrum and the cerebellum. In the submandibular gland, specific mRNA was found mainly in striated intralobular ducts and interlobular ducts. The expression of cystatin C in brain tissue is of particular interest, as the inhibitor appears to be involved in certain neurological diseases. The main production of cystatin C within the brain is believed to be by astrocytes. However, this work shows that also neurons from young, normal individuals express cystatin C.

Animals↗

PubMed1998

The role of protein kinase C signaling in activated DRA transcription.

Expression of human MHC HLA-DRA class II gene can be up-regulated in B cells by Ig cross-linking as well as by phorbol esters such as 12-O-tetradecanoyl phorbol 13-acetate (TPA). Induced DRA expression involves activation of restricted protein kinase C (PKC) isoforms, resulting in activated activator protein-1-dependent transcription. In this report expression profiles and activation of PKC were analyzed in human Raji B lymphoblastoid cells. Transient transfection analysis with target plasmids containing either DRA promoter (wild-type or mutated) or TPA response elements demonstrated that pretreatment with the selective PKC inhibitor GF 109203X repressed TPA-mediated activation. Western analysis performed on cellular fractions of resting cells and of TPA-activated cells revealed abundant expression of classical PKC-alpha (cPKC-alpha), cPKC-betaII, and atypical PKC-zeta isoforms and identified a sustained translocation of cPKC-alpha and cPKC-betaII from the cytosolic compartment to membranes. As expected, the distribution of atypical PKC-zeta was unaffected by TPA treatment and displayed an even distribution between cytosol and membranes. This finding was confirmed by immunofluorescence microscopy. The TPA-mediated translocation of cPKC-alpha and cPKC-betaII was not influenced by pretreatment with GF 109203X. Finally, functional activation and translocation of PKC were investigated with a selective in vitro kinase assay. Together, these results show that activated HLA-DRA expression in response to TPA treatment is strictly dependent on PKC activation acting on the X2 box of the DRA promoter and that selective inhibition of PKC enzymatic activity does not influence subcellular localization of expressed PKC isoenzymes. Thus, the translocation event per se occurs independently of PKC activation in these cells.

B-Lymphocytes↗

PubMed1997

Tissue distribution of human gp330/megalin, a putative Ca(2+)-sensing protein.

We used riboprobes and monoclonal antibodies to characterize tissue distribution of the human 550-kD homologue to gp330/megalin, primarily identified in the rat kidney. Human gp330/megalin mRNA and protein are readily identified in human parathyroid cells, placental cytotrophoblasts, kidney proximal tubule cells, and epididymal epithelial cells. The immunoreactivity is found on the surface of the cells and is heterogeneously downregulated in parathyroid hyperplasia and adenomas. Cells of the proximal kidney tubule and epididymis express the protein on their luminal aspect. Moreover, the protein is expressed in Type II pneumocytes, mammary epithelial and thyroid follicular cells, and the ciliary body of the eye. Sequence analysis of cDNA fragments, obtained by RT-PCR, revealed identical nucleotide sequences in parathyroid, kidney, placenta, epididymis, and lung. Immunohistochemistry for parathyroid hormone-related protein (PTHrP) revealed partial co-expression with human gp330/megalin in parathyroid, placenta, and mammary gland. The findings substantiate human gp330/megalin expression in a variety of human tissues expected to possess calcium-sensing functions. It may constitute a protein of utmost importance to adult and fetal calcium homeostasis, although other important functions may also be coupled to this exceptionally large protein with highly restricted tissue distribution.

Amino Acid Sequence↗

PubMed1996

Evolutionary relationship between human major histocompatibility complex HLA-DR haplotypes.

HLA-DR haplotypes of the human major histocompatibility complex are organized in five different groups. They can be identified based on the serological specificity expressed by the polymorphic DRB1 locus and by the presence of a characteristic set of DRB genes. The nucleotide sequences of introns 4 and 5 of the two DRB genes (DRB1(*)01 and DRB6(*)01 ) from a DR1 haplotype and the three DRB genes (DRB1(*)15, DRB6(*)15 , and DRB5(*)15 ), from a DR51 haplotype were determined. This study identified endogenous retroviral long terminal repeat elements (ERV9 LTR) located at identical positions in intron 5 of the DRB1 genes in both the DR1 and DR51 haplotypes. Phylogenetic analyses revealed a close evolutionary relationship between these two haplotypes. The DRB5 gene, unique for the DR51 haplotype, may have been lost by a recent gene deletion event creating the DR1 haplotype. A model for the evolution of the human DR haplotypes involving separate duplication and contraction events is presented.

Base Sequence↗

PubMed1995

The myrosinase gene family in Arabidopsis thaliana: gene organization, expression and evolution.

Myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1.) is in Brassicaceae species such as Brassica napus and Sinapis alba encoded by two differentially expressed gene families, MA and MB, consisting of about 4 and 10 genes, respectively. Southern blot analysis showed that Arabidopsis thaliana contains three myrosinase genes. These genes were isolated from a genomic library and two of them, TGG1 and TGG2, were sequenced. They were found to be located in an inverted mode with their 3' ends 4.4 kb apart. Their organization was highly conserved with 12 exons and 11 short introns. Comparison of nucleotide sequences of TGG1 and TGG2 exons revealed an overall 75% similarity. In contrast, the overall nucleotide sequence similarity in introns was only 42%. In intron 1 the unusual 5' splice border GC was used. Phylogenetic analyses using both distance matrix and parsimony programs suggested that the Arabidopsis genes could not be grouped with either MA or MB genes. Consequently, these two gene families arose only after Arabidopsis had diverged from the other Brassicaceae species. In situ hybridization experiments showed that TGG1 and TGG2 expressing cells are present in leaf, sepal, petal, and gynoecium. In developing seeds, a few cells reacting with the TGG1 probe, but not with the TGG2 probe, were found indicating a partly different expression of these genes.

Amino Acid Sequence↗