Cell therapy for diabetes using piscine islet tissue.

The islet tissue, called Brockmann bodies, in certain teleost fish is anatomically distinct from the pancreatic exocrine tissue and can be easily identified macroscopically. Expensive islet isolation procedures, such as required when procuring islet tissue from mammalian pancreases, are unnecessary. Tilapia islets transplanted into diabetic athymic nude mice will produce long-term normoglycemia and mammalian-like glucose tolerance profiles. Encapsulated tilapia islets function well after transplantation into euthymic recipients. Additionally, tilapia are potentially ideal xenogeneic donors because of markedly lower donor production costs, minimal islet procurement costs, and possibly decreased xenozoonotic potential relative to mammalian donors. Tilapia islets appear to be appropriately glucose responsive with high insulin output, can be cryopreserved, and are much more resistant to hypoxia than mammalian islets. Because tilapia and human insulin differ by 17 amino acids, we have cloned, sequenced, and modified the tilapia insulin gene by site-directed mutagenesis resulting in a tilapia insulin gene that codes for "humanized" insulin while still maintaining all of the tilapia regulatory (noncoding) sequences. We have now produced small numbers of founder transgenic tilapia with incorporation of our humanized tilapia insulin gene construct, and we have shown transmission and expression of the transgene in the beta cells and serum of their Fl offspring. Our ultimate goal is to achieve homologous recombination and to breed for homozygosity for the hybrid insulin gene. Subsequent generations of transgenic tilapia will undergo a program of genomic optimization selecting for growth, survival, and fecundity as well as stability of the transgene. Islets from the resulting transgenic fish, after extensive characterization, could be harvested, encapsulated, and then transplanted into diabetic patients.

PNRC: a proline-rich nuclear receptor coregulatory protein that modulates transcriptional activation of multiple nuclear receptors including orphan receptors SF1 (steroidogenic factor 1) and ERRalpha1 (estrogen related receptor alpha-1).

PNRC (proline-rich nuclear receptor coregulatory protein) was identified using bovine SF1 (steroidogenic factor 1) as the bait in a yeast two-hybrid screening of a human mammary gland cDNA expression library. PNRC is unique in that it has a molecular mass of 35 kDa, significantly smaller than most of the coregulatory proteins reported so far, and it is proline-rich. PNRC's nuclear localization was demonstrated by immunofluorescence and Western blot analyses. In the yeast two-hybrid assays, PNRC interacted with the orphan receptors SF1 and ERRalpha1 in a ligand-independent manner. PNRC was also found to interact with the ligand-binding domains of all the nuclear receptors tested including estrogen receptor (ER), androgen receptor (AR), glucocorticoid receptor (GR), progesterone receptor (PR), thyroid hormone receptor (TR), retinoic acid receptor (RAR), and retinoid X receptor (RXR) in a ligand-dependent manner. Functional AF2 domain is required for nuclear receptors to bind to PNRC. Furthermore, in vitro glutathione-S-transferase pull-down assay was performed to demonstrate a direct contact between PNRC and nuclear receptors such as SF1. Coimmunoprecipitation experiment using Hela cells that express PNRC and ER was performed to confirm the interaction of PNRC and nuclear receptors in vivo in a ligand-dependent manner. PNRC was found to function as a coactivator to enhance the transcriptional activation mediated by SF1, ERR1 (estrogen related receptor alpha-1), PR, and TR. By examining a series of deletion mutants of PNRC using the yeast two-hybrid assay, a 23-amino acid (aa) sequence in the carboxy-terminal region, aa 278-300, was shown to be critical and sufficient for the interaction with nuclear receptors. This region is proline rich and contains a SH3-binding motif, S-D-P-P-S-P-S. Results from the mutagenesis study demonstrated that the two conserved proline (P) residues in this motif are crucial for PNRC to interact with the nuclear receptors. The exact 23-amino acid sequence was also found in another protein isolated from the same yeast two-hybrid screening study. These two proteins belong to a new family of nuclear receptor coregulatory proteins.

N-terminal targeting of guanine nucleotide exchange factors (GEF) for ADP ribosylation factors (ARF) to the Golgi.

B2-1 (cytohesin-1) is a member of a group of proteins (including ARNO and ARNO3) that are all of similar size and domain composition. The three proteins contain an N-terminal coiled-coil domain, followed by a Sec7 and a pleckstrin homology (PH) domain. While it is well established that the Sec7 domain functions as a guanine nucleotide exchange factor (GEF) for ADP-ribosylation factors (ARFs) and the PH domain anchors the proteins to membrane phosphoinositols, the function of the N-terminal domain is unknown. Here we show that the N terminus of B2-1 (residues 1-54) is necessary and sufficient to target the protein to the Golgi. The Sec7+PH domains of B2-1 (residues 55-398) are not sufficient for Golgi localization. Further deletion analysis and point mutagenesis indicate that the coiled-coil domain within the N terminus is responsible for Golgi targeting. Furthermore, ARNO and ARNO3 N termini also have the same capability of targeting to the Golgi. We conclude that the N-terminal, (&agr;)-helical, coiled-coil domain is used to target this family of proteins to the Golgi complex.

B2-1, a Sec7- and pleckstrin homology domain-containing protein, localizes to the Golgi complex.

B2-1 is a human protein that contains both a Sec7 and a pleckstrin homology domain. The yeast Sec7 protein was previously shown to be involved in vesicle formation in the Golgi and endoplasmic reticulum. Recently, several groups have shown that B2-1 and highly similar proteins (e.g., ARNO, ARNO3) have varied cellular functions and subcellular locations. One of these is an association of the B2-1 Sec7 domain with the plasma membrane, binding to the cytoplasmic portion of the integrin beta2 chain (CD18) and is postulated to be involved in inside-out signaling. Other groups have shown that B2-1 and these related proteins are guanine nucleotide-exchange factors that act upon ADP ribosylation factors (ARFs) and are localized to the Golgi or plasma membrane. Here we report the subcellular localization of B2-1 protein. Interestingly, B2-1 does not localize to the plasma membrane but rather associates with a distinct Golgi complex compartment. B2-1's distribution can be disrupted by brefeldin A, a drug that rapidly disrupts the Golgi apparatus by inhibiting ARF activity. Furthermore, transient transfection of GFP-tagged B2-1 shows Golgi complex targeting. Excessive overexpression of transfected B2-1 causes partial Golgi dispersion.

Expression and temperature-dependent regulation of the beta2-microglobulin (Cyca-B2m) gene in a cold-blooded vertebrate, the common carp (Cyprinus carpio L.).

Expression of beta2-microglobulin (beta2m) in the common carp was studied using a polyclonal antibody raised against a recombinant protein obtained from eukaryotic expression of the Cyca-B2m gene. Beta2m is expressed on peripheral blood Ig+ and Ig lymphocytes, but not on erythrocytes and thrombocytes. In spleen and pronephros, dull- and bright-positive populations could be identified correlating with the presence of erythrocytes, thrombocytes, and mature leucocytes or immature and mature cells from the lympho-myeloid lineage, respectively. Thymocytes were shown to be comprised of a single bright-positive population. The Cyca-B2m polyclonal antiserum was used in conjunction with a similarly produced polyclonal antiserum to an MHC class I (Cyca-UA) alpha chain to investigate the expression of class I molecules on peripheral blood leucocytes (PBL) at different permissive temperatures. At 12 degrees C, a temporary downregulation of class I molecules was demonstrated, which recovered to normal levels within 3 days. However, at 6 degrees C, a lasting absence of class I cell-surface expression was observed, which could be restored slowly by transfer to 12 degrees C. The expression of immunoglobulin molecules on B cells was unaffected by temperature changes. The absence of the class I cell-surface expression was shown to be the result of a lack of sufficient Cyca-B2m gene transcription, although Cyca-UA mRNA was present at comparable levels at all temperatures. This suggests that class I expression is regulated by a temperature-sensitive transcription of the Cyca-B2m gene.

Cloning, sequencing and characterization of the tilapia insulin gene.

Using degenerate primers based on insulin sequences from other organisms, we report the cloning of the complete tilapia (Oreochromis niloticus) insulin gene. Using nested primers and a cassette ligation strategy we have also cloned 932 base pairs (bp) of 5' flanking and 1152 bp of 3' flanking sequence. The tilapia insulin gene has the similar three exon (one untranslated), two intron distribution found in all insulin genes sequenced to date. However, intron 1 is unique in having a smaller size (73 bp) than found in other organisms. 5' RNA extension revealed the presence of two potential transcriptional start sites. A perfect TATA box is located at -30 bp from the first transcriptional start site. Interestingly, the 5' upstream region contains a microsatellite close to the same position of a unique minisatellite found only in humans and primates. The upstream region also contains several potential control elements to regulate insulin expression that are found in mammalian insulin genes.

Temporal trends in antibody production in captive grey, harp and hooded seals to a single administration immunocontraceptive vaccine.

The temporal production of antibody to a single-administration immunocontraceptive vaccine, known to be immunocontraceptive in free-ranging female grey seals (Halichoerus grypus), was studied in captive grey seals, harp seals (Phoca groenlandica) and hooded seals (Cystophora cristata). The vaccine is based on liposome delivery of porcine zona pellucida antigens. When measured by antigen capture, the response of hooded and harp seals to the vaccine was similar to the response of grey seals. Determination of antibody production by ELISA with protein A, ELISA with rabbit anti-seal immunoglobulin sera and SDS-PAGE after affinity chromatography confirmed the similarity in response to the vaccine by grey and harp seals, but suggested lower titers in hooded seals. The vaccine produced titers in captive, juvenile grey and harp seals known to be immunocontraceptive in wild, adult grey seals.

Evidence for a long-lasting single administration contraceptive vaccine in wild grey seals.

A single-administration birth control vaccine based on liposome delivery of porcine zona pellucida antigens reduced pup production in grey seals (Halichoerus grypus) by about 90%. Anti-porcine zona pellucida titers of individual seals with two or more recaptures were variable but without a diminishing trend during the 5 year post-immunization period. Seals that produced at least one or more pups during the 2-5 year post-immunization period when the vaccine is fully effective, had an average anti-porcine zona pellucida titer of 5% of the reference serum. In contrast, the subset of seals that did not reproduce but were recaptured during the breeding season had an average titer of 31% of the reference serum. As measured by antibody titers and pup production, there were no differences in efficacy of the vaccine in 14-, 20- and 21-year-old female grey seals.

Cloning a cDNA from human NK/T cells which codes for a protein with high proline content.

A cDNA clone, B4-2, was isolated from a natural killer (NK) minus T cell subtractive library. The B4-2 clone coded for an mRNA of 2061 bp in length. It encodes a deduced 327 aa protein with a calculated molecular mass of 35.2 kDa. Searching of B4-2 DNA and protein sequences against various databases revealed no high homology to other sequences. However, B4-2 has an unusually high proline content (13%), contains a putative nuclear targeting sequence, and has several SPXX motifs which are frequently found in gene regulatory proteins. One of the stretches of prolines in B4-2 closely resembles the ligand for proteins with SH3 domains. Northern hybridization data showed that B4-2 is not a lymphoid specific gene and is expressed in a hepatoma cell line and also weakly transcribed or absent in a variety of other cells. A polyclonal antiserum raised against recombinant B4-2 recognizes a 32-34 kDa protein in lymphocytes.

Cloning a cDNA from human NK/T cells which codes for an unusual leucine zipper containing protein.

A 1724 base pair (bp) clone, B3-1, was obtained from a human NK subtracted cDNA library and sequenced. The cDNA encoded a 324 amino acid protein with a calculated molecular mass of 36 kDa. The deduced protein did not contain any hydrophobic domains, suggesting that it was not secreted or membrane bound. Extensive database searches showed no significant overall homology to any known proteins or genes. The protein did, however, contain an unusually long (twice normal) leucine zipper and the nuclear targeting sequence found in many transcription factors and oncogenes. The cDNA also contained three repeats of the sequence 'ATTTA' in its 3' untranslated region, a motif associated with many oncogenes, transcription factors and interleukins. The mRNA for this gene is weakly expressed in resting NK/T cells.

Adventitious variability? The amino acid sequences of nonvertebrate globins.

1. The more than 140 amino acid sequences of non-vertebrate hemoglobins (Hbs) and myoglobins (Mbs) that are known at present, can be divided into several distinct groups: (1) single-chain globins, containing one heme-binding domain; (2) truncated, single-chain, one-domain globins; (3) chimeric, one-domain globins; (4) chimeric, two-domain globins; and (5) chimeric multi-domain globins. 2. The crystal structures of eight nonvertebrate Hbs and Mbs are known, all of them monomeric, one-domain globin chains. Although these molecules represent plants, prokaryotes and several metazoan groups, and although the inter-subunit interactions in the dimeric and tetrameric molecules differ from the ones observed in vertebrate Hbs, the secondary structures of all seven one-domain globins retain the characteristic vertebrate "myoglobin fold". No crystal structures of globins representing the other four groups have been determined. 3. Furthermore, a number of the one-, two- and multi-domain globin chains participate in a broad variety of quaternary structures, ranging from homo- and heterodimers to highly complex, multisubunit aggregates with M(r) > 3000 kDa (S. N. Vinogradov, Comp. Biochem. Physiol. 82B, 1-15, 1985). 4. (1) The single-chain, single-domain globins are comparable in size to the vertebrate globins and exhibit the widest distribution. (A) Intracellular Hbs include: (i) the monomeric and polymeric Hbs of the polychaete Glycera; (ii) the tetrameric Hb of the echiuran Urechis; (iii) the dimeric Hbs of echinoderms such as Paracaudina and Caudina; and (iv) the dimeric and tetrameric Hbs of molluscs, the bivalves Scapharca, Anadara, Barbatia and Calyptogena. (B) Extracellular Hbs include: (i) the multiple monomeric and dimeric Hbs of the larva of the insect Chironomus; (ii) the Hbs of nematodes such as Trichostrongylus and Caenorhabditis; (iii) the globin chains forming tetramers and dodecamers and comprising approximately 2/3 of the giant (approximately 3600 kDa), hexagonal bilayer (HBL) Hbs of annelids, e.g. the oligochaete Lumbricus and the polychaete Tylorrhynchus and of the vestimentiferan Lamellibrachia; and (iv) the globin chains comprising the ca 400 kDa Hbs of Lamellibrachia and the pogonophoran Oligobrachia. (C) Cytoplasmic Hbs include: (i) the Mbs of molluscs, the gastropods Aplysia, Bursatella, Cerithedea, Nassa and Dolabella and the chiton Liolophura; (ii) the three Hb of the symbiont-harboring bivalve Lucina; (iii) the dimeric Hb of the bacterium Vitreoscilla; and (iv) plant Hbs, including the Hbs of symbiont-containing legumes (Lgbs), the Hbs of symbiont-containing non-leguminous plants and the Hbs in the roots of symbiont-free plants.(ABSTRACT TRUNCATED AT 400 WORDS)

Kinetics of ligand binding to Pseudoterranova decipiens and Ascaris suum hemoglobins and to Leu-29-->Tyr sperm whale myoglobin mutant.

The kinetics of binding of O2, CO, and NO to the octameric, two-domain hemoglobins of the parasitic nematodes Pseudoterranova decipiens and Ascaris suum were determined on nanosecond and picosecond time scales using flash photolysis. The two nematode hemoglobins have very similar kinetic properties. On the picosecond time scale, they exhibit an unusual behavior in showing a geminate reaction with oxygen that is biphasic and dependent on the flash intensity. The geminate reaction with NO is also faster and more complete than for sperm whale myoglobin; however, in contrast to the O2 reaction, it is homogeneous. In addition, the oxygen dissociation rate of P. decipiens hemoglobin, 0.0035 s-1, is as low as that of A. suum hemoglobin, 0.004 s-1 (Gibson, Q. H., and Smith, M. H. (1965) Proc. R. Soc. Lond. B Biol. Sci. 163, 206-214). A mutant of sperm whale myoglobin suggested by sequence alignment of the nematode hemoglobins, Leu-29-->Tyr, did not have kinetic properties similar to them.

Induction of a proteoglycan core protein mRNA in mouse T lymphocytes.

The mouse T lymphocyte cell line EL4.E1 synthesizes a proteoglycan core protein (PGCP) mRNA which is identical to serglycin mRNA found in mouse bone marrow-derived mast cells and a mouse mastocytoma cell line. PGCP mRNA was strongly induced in EL4.E1 cells by phorbol myristate acetate, which also induces mRNAs for several cytokines in these cells. In contrast to the induction of cytokine mRNAs, however, the induction of PGCP mRNA was not inhibited by Cyclosporine. PGCP mRNA was also inducible by allogeneic stimulation of normal mouse spleen cells, and by Con A stimulation of an Interleukin 2-producing T hybridoma cell line. A number of other cell lines expressed an identical or similar, mRNA, including two cytotoxic T cell lines, and three tumor cell lines related to bone marrow-derived cells. The levels of several proteoglycans have previously been reported to increase in cells of bone marrow origin under activating conditions, but this appears to be the first report of an induction of the corresponding PGCP mRNA by immune stimulation of T lymphocytes.

A commentary on: 'unexpected intron location in non-vertebrate globin genes', by: Moens et al. (FEBS letters, 312 (1992) 105-109).

We are submitting this commentary in order to prevent the confusion which Moens et al. may provoke in the minds of readers. Our comments are intended to point out the exclusion of some major issues and some errors which may mislead readers of this paper.

Immune function in free-ranging harbor seal (Phoca vitulina) mothers and their pups during lactation.

Immune function in harbor seal mothers and their pups during lactation was studied on Sable Island, Nova Scotia, Canada, during the springs of 1989 and 1990. Methods included total white blood cell and differential counts, a Protein A enzyme linked immunosorbent assay (ELISA) for total immunoglobulin G (IgG) quantification, and functionality testing of lymphocytes in vitro using the T-cell mitogen concanavalin A (ConA). Lymphocyte functionality and total IgG levels were reduced in the mothers at the end of lactation, suggesting a reduction in immune function, possibly as a result of the stress of fasting, or hormonal changes associated with lactation and estrus. By contrast, lymphocyte functionality and total IgG levels in pups were low at birth and higher at the end of lactation. Pups at birth and females late in lactation may therefore be more susceptible to infection by viral and bacterial agents. This study represents the first broad examination of immune function in a free-ranging pinniped population.

Characterization of beta 2-microglobulin transcripts from two teleost species.

Using degenerate primers based on published beta 2-microglobulin sequences we were able to obtain an expected 111 base pairs (bp) polymerase chain reaction (PCR) fragment from tilapia genomic DNA. The sequence of this fragment showed a high degree of similarity to mouse beta 2-microglobulin at the protein level. We used these primers in an "anchored PCR" to obtain a 213 bp PCR fragment from a carp cDNA library. This was then used to clone a full-length beta 2-microglobulin cDNA from carp. The carp sequence showed the highest similarity to rabbit beta 2-microglobulin. Both sequences showed strong similarities to all previously published vertebrate beta 2-microglobulin sequences. The predicted protein secondary structure of both the carp and tilapia clones was almost identical to the corresponding regions of previously known vertebrate beta 2-microglobulin protein sequences. When either the carp or tilapia probes were used against corresponding northern blots, they hybridized to a message of approximately 800-1000 bases long, which corresponds to the previously published lengths of beta 2-microglobulin mRNAs. Southern blotting indicated that beta 2-microglobulin was encoded by a single copy gene in both cases. Phylogenetic analysis indicated that the sequences were related to the beta 2-microglobulins of higher vertebrates but grouped together in an ancestral position.

Assignment of human B2-1 gene (D17S811E) to chromosome 17qter by PCR analysis of somatic cell hybrids and fluorescence in situ hybridization.

The human gene B2-1 has significant homology to the yeast gene SEC7. By PCR analysis of a human x rodent hybrid panel, the B2-1 gene was assigned to chromosome 17. Fluorescence in situ hybridization localized the gene to 17qter.

Did the ancestral globin gene of plants and animals contain only two introns?

All vertebrate globin genes contain two introns, while plant globin genes contain three. It is widely thought that the plant gene structure reflects the structure of the primordial globin gene and that a common ancestor of all animals lost the central intron shortly after the divergence of plants and animals more than one billion years ago. The recent discovery of a discordant central intron in some animal globin genes suggests that this model is incorrect. We propose that the typical vertebrate two-intron gene structure is the primordial eukaryotic form, and that following the divergence of plants and animals, a common ancestor of plants gained a central intron in the globin gene.