Recurrence of immunoglobulin A-kappa crystalline deposition disease after kidney transplantation

Cases of immunoglobulin A heavy chain and kappa light chain deposition disease are rare and their clinical presentations vary. We report one patient with histopathologic and clinical findings of a microangiopathic glomerulonephritis due to immunoglobulin A-kappa deposition. Ultrastructural studies revealed highly ordered deposits in the capillary lumen, mesangium, and basement membrane. The disease recurred at 2.5 years after a cadaveric kidney transplantation. Pulse steroid therapy was repeatedly effective in retarding further progression of renal deterioration in this patient.

Characterization of cis-regulating elements and trans-activating factors of the rat cardiac troponin T gene

To study the transcriptional regulation of the rat cardiac troponin T (cTnT) gene, chimeric genes composed of the upstream region (-757 to +193 base pairs (bp) relative to the transcription initiation site) of the cTnT gene and the bacterial chloramphenicol acetyltransferase (CAT) gene were constructed and transfected into primary cultures of neonatal cardiomyocytes and cardiac fibroblasts. Deletion analysis showed that a 41-bp fragment (-249 to -209 bp) containing the MEF-2-like motif is an essential element for minimal cardiac-specific expression of the rat cTnT gene. The proximal promoter (-208 to -1 bp) contains two consensus CArG boxes, one M-CAT motif, one AP2 site, and one TATA box. The construct (cTNT-208) composed of the CAT reporter gene driven by this proximal promoter did not show cardiac muscle-specific expression. Ligation of consensus MEF-2-like sequence into the upstream of this chimera only partially increased its ability to express in cardiomyocytes. These results suggest that the spacing among MEF-2-like motif and proximal promoter and/or the flanking sequences of the MEF-2-like motif are important in determining cardiac muscle-specific expression. By footprint analysis with a DNA fragment (-303 to +6 bp), we identified three novel regions (called A, B, and C) protected by protein extract from rat hearts, in addition to the known motifs such as MEF-2, M-CAT, and CArG. Gel retardation with the probe (-235 to -141 bp), containing the MEF-2-like motif, one of the CArG boxes, and the C region, or the 41-bp probe (-249 to -209 bp), containing the MEF-2-like motif, revealed different DNA-protein complexes formed by heart, skeletal muscle, and liver extracts. By using DNA affinity purification, DNA-binding proteins with apparent molecular masses of 22-26 kDa were identified from rat heart extract but not from skeletal and liver extracts, suggesting the involvement of cardiac-specific proteins in regulating the cTnT gene expression.

Isolation and characterization of two Saccharomyces cerevisiae genes that encode proteins that bind to (TG1-3)n single strand telomeric DNA in vitro

By screening lambda gt11 libraries with a radiolabeled (TG1-3)n oligonucleotide, two Saccharomyces cerevisiae genes were identified that encode polypeptides that recognize the single-stranded telomeric repeat sequence (TG1-3)n. The first gene, NSR1, a previously identified gene, encodes a protein involved in ribosomal RNA maturation and possibly in transport of proteins into the nucleus. The second gene, GBP2 (G-strand Binding Protein), is an anonymous open reading frame from chromosome III. These two genes contain RNA recognition motifs (RRMs) that are found in proteins that interact with RNA. Both Nsr1p and Gbp2p bind specifically to yeast single strand (TG1-3)n DNA in vitro. To test whether these two proteins associate with telomeres in vivo, strains were constructed in which one or both of these genes were either disrupted or overexpressed. None of these alterations affected telomere length or telomere position effect. The potential role of these two (TG1-3)n binding proteins is discussed.

Characterization of the mechanism of cellular and cell free protein synthesis inhibition by an anti-tumor ribonuclease

Onconase, a protein with anti-tumor activity, causes potent inhibition of protein synthesis in the rabbit reticulocyte lysate (IC50 10(-11) M) and when microinjected into Xenopus oocytes (IC50 10(-10) M). Onconase is a member of the RNase A superfamily; however, unlike RNase A, the mechanism of protein synthesis inhibition does not involve apparent degradation of lysate or cellular ribosomal RNAs. Rather, reticulocyte and oocyte tRNA is hydrolyzed after Onconase treatment. Furthermore, re-addition of tRNA to Onconase pretreated lysates or oocytes restores the translational capacity of the system. Taken together these results suggest that Onconase causes potent protein synthesis inhibition by a mechanism involving inactivation of cellular tRNA.

Erythrocyte tropomodulin binds to the N-terminus of hTM5, a tropomyosin isoform encoded by the gamma-tropomyosin gene

Tropomodulin is a 40.6-kDa protein that binds to one end of the rod-like tropomyosin and inhibits its cooperativity and binding to actin. In myofibrils, tropomodulin has been localized at or near the free end of thin filaments. Using recombinant and chimeric molecules in a solid-phase binding assay, we demonstrate that it is the N-terminus of tropomyosin that interacts with tropomodulin. Among several tropomyosin isoforms tested, hTM5 encoded by the human gamma-tropomyosin gene has the highest affinity toward human erythrocyte tropomodulin. Tropomodulin may, therefore, regulate the length and/or organization of actin filaments by differential binding to tropomyosin isoforms. hTM5 exists in the human erythrocyte membrane skeleton. In non-muscle cells, tropomodulin may block the head-to-tail association of tropomyosins and their interaction with actin at the pointed end of actin filaments by preferentially binding to TM5 at its N-terminus.

Hemiballism-hemichorea and non-ketotic hyperglycaemia

Three patients with hemiballism-hemichorea caused by non-ketotic hyperglycaemia are presented, two of whom had hyperosmolar non-ketotic hyperglycaemic syndrome. In two of the three patients, the hyperkinesia was the initial presenting symptom of their diabetes mellitus. The hypersensitivity of the postmenopausal dopamine receptor, decreased gamma-aminobutyric acid in the brain in non-ketotic hyperglycaemia, coexisting lacunar infarct in the basal ganglion, and pre-existing metabolic dysfunction in the basal ganglion may all have played a part in the pathogenesis of this movement disorder.

Overexpression of human fibroblast caldesmon fragment containing actin-, Ca++/calmodulin-, and tropomyosin-binding domains stabilizes endogenous tropomyosin and microfilaments

Fibroblast caldesmon is a protein postulated to participate in the modulation of the actin cytoskeleton and the regulation of actin-based motility. The cDNAs encoding the NH2-terminal (aa.1-243, CaD40) and COOH-terminal (aa.244-538, CaD39) fragments of human caldesmon were subcloned into expression vectors and we previously reported that bacterially produced CaD39 protein retains its actin-binding properties as well as its ability to enhance low M(r) tropomyosin (TM) binding to actin and to inhibit TM-actin-activated HMM ATPase activity in vitro (Novy, R. E., J. R. Sellers, L.-F. Liu, and J. J.-C. Lin. 1993. Cell Motil. Cytoskeleton. 26:248-261). Bacterially produced CaD40 does not bind actin. To study the in vivo effects of CaD39 expression on the stability of actin filaments in CHO cells, we isolated and characterized stable CHO transfectants which express varying amounts of CaD39. We found that expression of CaD39 in CHO cells stabilized microfilament bundles as well as endogenous TM. CaD39-expressing clones displayed an increased resistance to cytochalasin B and Triton X-100 treatments and yielded increased amounts of TM-containing actin filaments in microfilament isolation procedures. In addition, analysis of these clones with immunoblotting and indirect immunofluorescence microscopy with anti-TM antibody revealed that stabilized endogenous TM and enhanced TM-containing microfilament bundles parallel increased amounts of CaD39 expression. The increased TM observed corresponded to a decrease in TM turnover rate and did not appear to be due to increased synthesis of endogenous TM. Additionally, the phenomenon of stabilized TM did not occur in stable CHO clones expressing CaD40. Therefore, it is likely that CaD39 can enhance TM's binding to F-actin in vivo, thus reducing TM's rate of turnover and stabilizing actin microfilament bundles.

The isolation of differentially expressed genes in fibroblast growth factor stimulated BC3H1 cells by subtractive hybridization

We have developed a subtractive hybridization procedure based on the hybridization of a single-stranded phagemid cDNA library (target) to biotinylated RNA (driver). We have applied this method to fibroblast growth factor (FGF) induced-uninduced mouse brain tumor-derived muscle-like cell. BC3Hl cDNA libraries. After hybridization to a C(o)t value of 1000, cDNAs common to the target and driver populations were subtracted up to 231-fold, whereas several highly induced genes were enriched from 2-15-fold. Interestingly, moderately induced genes (e.g., the 12-fold-induced nur/77 gene) were subtracted even at a low C(o)t value of 50. Therefore, at every C(o)t tested, subtractive hybridization tended to equalize the uninduced and moderately induced common sequences within target populations regardless of the abundance of the gene species. These observations suggest that subtractive hybridization should only be used for identifying target genes that are either uniquely expressed or highly induced.

The variant mRNA isoform of human metastasis gene (CD44V) detected in the cell lines of human hepatocellular carcinoma

The interaction of the cell surface receptor CD44 molecular with its ligands (addressin, extracellular matrix etc.,) plays an important role in fulfilling the lymphocyte homing and immune reaction. Recently alternatively spliced products of CD44 gene are found to be involved in tumor metastasis as well. Our report found that CD44 prototype RNA (CD44S) was present in all five tumor cell lines. Isoform CD44 RNA (CD44V) was recognized in three metastasized hepatocellular carcinoma cell lines, J5, HCC36, HEP3B. In addition, the J5 CD44 RNA isoform expressed two distinct transcripts which are of the same size as MDA-231 breast tumor cell line. The MDA-231 CD44 RNA variant (CD44V) has been confirmed to contain metastasis domain 4 and 5. It is implicated that the alternative RNA splicing may also play a major role in hepatocellular carcinoma metastasis.

The 3' flanking region of the human erythropoietin-encoding gene contains nitrogen-regulatory/oxygen-sensing consensus sequences and tissue-specific transcriptional regulatory elements

We have reported the identification of a classical canonical CAAT box, TATA boxes and other transcriptional regulatory elements in the 5' flanking region of the human erythropoietin (hEp)-encoding gene [Lee-Huang et al., Gene 128 (1993) 227-236]. These elements were not found in the hEp genomic clones reported by others. Our genomic clone extends in both directions beyond any reported clones, by 3.9 kb on the 5' side and by 1.8 kb on the 3' side. Many important regulatory elements are found in these extended flanking regions. We report here the genomic structure of the extended 3' flanking region of hEp. This region contains the following regulatory elements: nitrogen-regulatory/oxygen-sensing consensus sequences, 5'-TTTTGCA and 5'-CCCTGCA; tissue-specific regulatory elements, including binding sites for A-activator, 5'-GTGGTGCAA; for DBP, 5'-TGATTTTGT; for HNF, 5'-T(A/G)TTTGT; and for C/EBP, 5'-T(T/G) (T/G)TGCAAT; a lymphokine-responsive element, 5'-GTGAAACCCC (Rev), as well as binding sites for AP and Sp1. In addition, the nucleotide (nt) sequence in this region is rich in inverted repeats (palindromes) that allow the formation of hairpin loops. A total of 14 potential stem loops with a maximum loop size of 20 nt are found. The identification of these regulatory elements in hEp should provide further insight into the tissue-specific and inducible expression of hEp. Such knowledge should be useful in the clinical modulation of erythropoiesis under physiologic and pathologic conditions.

Forced expression and assembly of rat cardiac troponin T isoforms in cultured muscle and nonmuscle cells

Cardiac troponin T (cTnT), a tropomyosin (TM)-binding subunit of the troponin complex, undergoes a developmentally regulated isoform switch from embryonic form to adult form in the rat heart. To investigate the in vivo assembly of cTnT isoforms, we transiently transfected cDNA clones of either rat cTnT isoform into nonmuscle CHO cells and chick embryo myogenic (CEM) cells. As determined by Western blotting, both isoforms can be expressed in CHO and CEM cells. The expressed proteins had the same mobility as native rat cTnT proteins on SDS polyacrylamide gels and were recognized by anti-TnT antibodies. Conventional and confocal microscopy of transfected cells, double-labelled with antibodies against cTnT and against TM, revealed that neither isoform appears to associate with the nonmuscle TM in CHO cells, although both are able to colocalize with muscle TM-containing microfilament bundles in the myogenic CEM cells. There was no appreciable cTnT isoform-related difference in association with TM, suggesting that the functional significance of isoform variability in rat cTnT does not correspond to an assembly advantage for the maturing cardiac thin filament. To help determine whether cTnT nonassembly in CHO environment is primarily due to the nonmuscle nature of the endogenous TM, or if it involves the absence of other factors specific to muscle, we have isolated several stably-transfected clones of skeletal beta TM-expressing CHO cells which incorporate this muscle TM onto stress fibres. When either isoform of cTnT was transiently expressed in these beta TM-CHO cells, the strictly filamentous beta TM staining pattern was no longer observed. Instead, beta TM codistributed with cTnT in brightly staining aggregates not associated with the intact stress fibres. This suggests that both isoforms of cTnT are interacting with the beta TM in the nonmuscle environment and that other muscle-specific proteins may indeed be required for stable assembly of cTnT onto microfilaments. It also suggests that the interaction between cTnT and muscle TM is stronger than that between muscle TM and nonmuscle microfilaments.

Partial antinociceptive cross-tolerance to intracerebroventricular beta-endorphin in mice tolerant to systemic morphine

The effects of subcutaneous morphine pellet-implantation on antinociception induced by intracerebroventricular (i.c.v.) administration of beta-endorphin or morphine and intrathecal (i.t.) administration of morphine, [D-Pen2,D-Pen5]enkephalin (DPDPE), [D-Ala2,NMePhe4,Gly5-ol]enkephalin (DAMGO), serotonin or norepinephrine were studied in male ICR mice. The tail-flick and hot-plate responses were used for antinociceptive tests. The ED50 values for i.c.v. administered morphine for antinociception in morphine pellet-implanted mice were increased from 3.3- and 2.2-fold at 0 h to 14.2- and 19.0-fold at 4 h and declined to 4.8- and 3.0-fold at 8 h after pellet removal in the tail-flick and hot-plate tests, respectively. On the other hand, the ED50 values for i.c.v. administered beta-endorphin for antinociception were only slightly increased (1.7- to 5.1-fold increases) throughout the same time course. The inhibition of the tail-flick response induced by i.t. injection of morphine, DPDPE and serotonin, but not norepinephrine or DAMGO, was attenuated in morphine pellet-implanted mice. These findings are consistent with previous studies indicating that different neuronal mechanisms are involved in morphine- and beta-endorphin-induced antinociception.

Telomeric DNA binding proteins

The physical ends of eukaryotic chromosomes form a specialized nucleoprotein complex composed of DNA and DNA binding proteins. This nucleoprotein complex, termed the telomere, is essential for chromosome stability. In most organisms, the DNA portion of the nucleo-protein complex consists of simple tandem DNA repeats with one strand guanine rich. The protein portion of the complex is less well understood. The experiments presented in two recent papers represent different stages in the characterization of the telomeric DNA binding proteins. The first paper presents a structure-function study of the Oxytricha telomeric DNA binding proteins and the second paper shows the identification and initial characterization of a telomeric DNA binding activity from Xenopus laevis. These two reports provided valuable information in understanding the structure and function of telomeres.

The human erythropoietin-encoding gene contains a CAAT box, TATA boxes and other transcriptional regulatory elements in its 5' flanking region

We have reported the cloning and expression of a human erythropoietin (hEp)-encoding cDNA [Lee-Huang, Proc. Natl. Acad. Sci. USA 81 (1984) 2708-2712]. Using this hEp cDNA as a probe, we isolated a 9.3-kb BamHI genomic Ep clone from a human leukocyte library soon thereafter. The size and restriction map of this clone is in agreement with restriction analysis of human genomic DNA probed with the hEp cDNA, demonstrating that this clone is representative of the single hEp gene. This clone is unique in that it extends beyond any reported hEp genomic clone by 3.9 kb on the 5' side and by 1.8 kb on the 3' side. The promoter function of the newly described 5' flanking region has been demonstrated by the expression of biologically active hEp in transfected cells. We find that, despite reports to the contrary, hEp does contain classic canonical TATA boxes and a CAAT box. The 5'-flanking region also contains cytokine-responsive consensus sequences, tissue-specific and metal-responsive elements, CRE and GRE sites, and binding sites for transcription factors, including AP1, NF-kappa beta and Sp1. These regulatory elements have not been found in the hEp genomic clones thus far reported. The identification of these elements and their precise localization in hEp should be useful in studying the regulation of hEp expression, as well as in gene therapy and physiologic modulation of this hormone.

IgG and IgA classes of anti-neutrophil cytoplasmic autoantibodies in a 13-year-old girl with recurrent Henoch-Schonlein purpura

We describe a 13-year-old girl with recurrent Henoch-Schonlein purpura whose symptoms were precipitated by upper respiratory tract infections. Her serum was positive for both IgG and IgA classes of anti-neutrophil cytoplasmic autoantibodies by immunofluorescence. The titers of both autoantibodies correlated with disease activity. The immunopathology underlying these findings is discussed.

Expression of smooth muscle and nonmuscle tropomyosins in Escherichia coli and characterization of bacterially produced tropomyosins

The cDNA encoding the beta-tropomyosin isoform of chicken smooth muscle (CSM beta) was constructed and expressed in Escherichia coli to produce recombinant, unacetylated beta-tropomyosin (rCSM beta) and a mutant (rCSM beta-7) with a 7-residue deletion at its amino-terminus. Furthermore, the cDNA coding for human fibroblast tropomyosin isoform 3 (hTM3) was also used to produce unacetylated hTM3 (called PEThTM3). All of bacterially-made tropomyosins were high alpha-helical in structure as judged by CD analysis and resistant to heat denaturation. Both the rCSM beta and PEThTM3 exhibited saturable binding to F-actin with apparent binding constants of 1.14 x 10(6) and 2.78 x 10(6) M-1, respectively. The bacterially made, unacetylated smooth muscle tropomyosin (rCSM beta) appeared to have a comparable actin-binding affinity to that of gel-purified CSM beta homodimer (1.25 x 10(6) M-1) but significantly lower than that for native gizzard tropomyosin (CSM-TM) heterodimer (1.28 x 10(7) M-1). The amino-terminal deletion mutant rCSM beta-7 failed to bind to F-actin. Effects of gizzard caldesmon on the actin binding of these bacterially made tropomyosins were also examined. Under the binding condition containing 0.5 mM MgCl2 and 30 mM KCl, caldesmon greatly enhanced the binding of rCSM beta to F-actin. However, under the same condition, there was a slight enhancement in the actin-binding for gel-purified CSM beta or PEThTM3 (1.2-1.6-fold stimulation) and no enhancement for native gizzard tropomyosin. Neither the presence of caldesmon nor native gizzard tropomyosin induced detectable binding of the amino-terminal deletion mutant rCSM beta-7 to F-actin. These results clearly imply the importance of the amino-terminal 7 amino-acid residues of CSM beta in the actin binding and the caldesmon enhancement.

Electron microscopic images suggest both ends of caldesmon interact with actin filaments

An improved rotary shadowing technique enabled us to visualize chicken gizzard caldesmon (CaD) and its complexes with one or two covalently linked calmodulin (CaM) molecules by electron microscopy. Using a monoclonal antibody against an epitope in the N-terminal region of CaD (anti-N), we can now identify the end of the molecule that is involved in binding to another protein molecule. Thus in the 1:1 complex of CaD and CaM, the CaM molecule was almost always associated with the C-terminus of CaD, indicating preferential CaM-binding to the C-terminal region. We have also studied binding of CaD to filamentous actin (F-actin), using an EM technique that avoids spraying or freeze drying and thereby preserves the structure of F-actin. Only one end of CaD appeared to bind to F-actin, leaving the rest of the molecule projecting away from the filament. While the majority of anti-N bound at the free end of CaD, some antibody molecules were found on F-actin. These findings suggest that either end of CaD can bind to F-actin. Experiments using a monoclonal antibody against the C-terminus of CaD (anti-C) supported this idea. When the native thin filaments that contain endogenous CaD were incubated with anti-N, almost all the bound antibodies were found on the filaments, indicating that the N-terminal regions of CaD interact with actin, and that the binding affinity of the N-terminal region of CaD for actin is higher in vivo than that in vitro, either because the properties of CaD have been altered during purification, or because of the presence of some other component(s) associated with the native filaments.

Postinfectious encephalopathy in a child following Campylobacter jejuni enteritis

We report a case of acute postinfectious encephalopathy in a child following Campylobacter jejuni enteritis. Serial MR scans showed lesions involving predominantly gray matter and the adjacent subcortical white matter--findings different from those in other immune-mediated disorders, such as systemic lupus erythematosus, in which either white or gray matter may be involved, and acute disseminated encephalomyelitis, in which white matter abnormalities predominate with involvement of the subcortical white matter.

Human fibroblast tropomyosin isoforms: characterization of cDNA clones and analysis of tropomyosin isoform expression in human tissues and in normal and transformed cells

A tropomyosin-specific oligonucleotide probe (REN29) designed to hybridize to all known human tropomyosin isoforms was used to study tropomyosin mRNA levels in normal and transformed human cells. At least four different sizes of RNAs were detected in normal human fibroblast KD cells by Northern blot analysis. The major bands of 1.1 kb RNA for hTM1 and 3.0 kb RNA for hTM4 were decreased substantially in various transformed cell lines. One of the minor RNA bands (2.0 kb for hTM2 and hTM3) appeared to be absent in a human pancreatic carcinoma cell line. The level of the other minor RNA band (2.5 kb for hTM5) was found to be unchanged or slightly decreased in transformed cells. This differential expression of tropomyosin isoforms at the RNA level was not totally in agreement with the difference in the protein amounts found in normal and transformed cells, suggesting that translational control may also play an important role in the expression of some tropomyosin isoforms. The REN29 probe was further used to screen lambda gt10 and lambda gt11 cDNA libraries, which were constructed from poly(A)+ RNAs of human fibroblast cell lines HuT-14 and WI-38, respectively. In addition to cDNA clones encoding known isoforms, we obtained three classes of new cDNA clones that encode two low M(r) isoforms (hTM5a and hTM5b), and a high M(r) isoform (hTMsm alpha). Sequence comparison revealed that hTM5a and hTM5b are alternatively spliced products derived from the same gene that encodes hTM2 and hTM3. Northern blot analysis and amino acid sequence comparison suggested that the hTMsm alpha represents a smooth muscle tropomyosin which is also expressed in human fibroblasts. The exon specific for, and common to, hTM5a and hTM5b was found to be highly expressed in small intestine. However, there was no detectable expression of this exon in stomach and skeletal muscle. The difference in tissue-specific expression suggests that different isoforms may perform distinct functions in different tissues.

In vitro functional characterization of bacterially expressed human fibroblast tropomyosin isoforms and their chimeric mutants

At least eight tropomyosin isoforms (hTM1, hTM2, hTM3, hTM4, hTM5, hTM5a, hTM5b, and hTMsm alpha) are expressed from four distinct genes in human fibroblasts. In order to elucidate isoform properties, we have subcloned hTM3 and hTM5 full-length cDNAs, as well as their chimeric cDNAs into the bacterial expression pET8C system. Bacterially expressed tropomyosin isoforms (called PEThTM3, PEThTM5, PEThTM5/3, and PEThTM3/5) were purified and characterized. Under optimal binding conditions, the binding of PEThTM5 isoform to F-actin was stronger than the PEThTM3 isoform. However, analysis of actin-binding by the McGhee and von Hippel equation revealed that PEThTM3 exhibits higher cooperativity in binding than PEThTM5 does. Furthermore, the chimera PEThTM5/3 which possessed the N-terminal fragment of hTM5 fused to the C-terminal fragment of hTM3 had even stronger actin binding ability. The reverse chimera PEThTM3/5 which possessed the N-terminal fragment of hTM3 fused to the C-terminal fragment of hTM5 demonstrated greatly reduced affinity to actin filaments. In addition, both chimeras had different KCl requirements for optimal binding to F-actin than their parental tropomyosins. A bacterially made C-terminal fragment of human fibroblast caldesmon (PETCaD39) and native chicken gizzard caldesmon were both able to enhance the actin-binding of these bacterially expressed tropomyosins. However, PETCaD39's enhancement of binding to F-actin was greater for PEThTM5 than PEThTM3. Under 30 mM KCl and 4 mM MgCl2, the low M(r) isoform PEThTM4 appeared to be able to amplify the actin-activated HMM ATPase activity by 4.7 fold, while the high M(r) isoform PEThTM3 stimulated the activity only 1.5 fold. The higher enhancement of ATPase activity by PEThTM5 than by PEThTM3 suggested that the low M(r) isoform hTM5 may be more involved in modulating nonmuscle cell motility than hTM3. These results further suggested that different isoforms of tropomyosin might have finite differences in their specific functions (e.g., cytoskeletal vs. motile) inside the cell.