Macrophage-associated wound healing contributes to African green monkey SIV pathogenesis control.

Natural hosts of simian immunodeficiency virus (SIV) avoid AIDS despite lifelong infection. Here, we examined how this outcome is achieved by comparing a natural SIV host, African green monkey (AGM) to an AIDS susceptible species, rhesus macaque (RM). To asses gene expression profiles from acutely SIV infected AGMs and RMs, we developed a systems biology approach termed Conserved Gene Signature Analysis (CGSA), which compared RNA sequencing data from rectal AGM and RM tissues to various other species. We found that AGMs rapidly activate, and then maintain, evolutionarily conserved regenerative wound healing mechanisms in mucosal tissue. The wound healing protein fibronectin shows distinct tissue distribution and abundance kinetics in AGMs. Furthermore, AGM monocytes exhibit an embryonic development and repair/regeneration signature featuring TGF-ß and concomitant reduced expression of inflammatory genes compared to RMs. This regenerative wound healing process likely preserves mucosal integrity and prevents inflammatory insults that underlie immune exhaustion in RMs.

Characterisation of the hepatitis B virus cross-species transmission pattern via Na+/taurocholate co-transporting polypeptides from 11 New World and Old World primate species.

The hepatic Na+/taurocholate co-transporting polypeptide (NTCP in man, Ntcp in animals) is the high-affinity receptor for the hepatitis B (HBV) and hepatitis D (HDV) viruses. Species barriers for human HBV/HDV within the order Primates were previously attributed to Ntcp sequence variations that disable virus-receptor interaction. However, only a limited number of primate Ntcps have been analysed so far. In the present study, a total of 11 Ntcps from apes, Old and New World monkeys were cloned and expressed in vitro to characterise their interaction with HBV and HDV. All Ntcps showed intact bile salt transport. Human NTCP as well as the Ntcps from the great apes chimpanzee and orangutan showed transport-competing binding of HBV derived myr-preS1-peptides. In contrast, all six Ntcps from the group of Old World monkeys were insensitive to HBV myr-preS1-peptide binding and HBV/HDV infection. This is basically predetermined by the amino acid arginine at position 158 of all studied Old World monkey Ntcps. An exchange from arginine to glycine (as present in humans and great apes) at this position (R158G) alone was sufficient to achieve full transport-competing HBV myr-preS1-peptide binding and susceptibility for HBV/HDV infection. New World monkey Ntcps showed higher sequence heterogeneity, but in two cases with 158G showed transport-competing HBV myr-preS1-peptide binding, and in one case (Saimiri sciureus) even susceptibility for HBV/HDV infection. In conclusion, amino acid position 158 of NTCP/Ntcp is sufficient to discriminate between the HBV/HDV susceptible group of humans and great apes (158G) and the non-susceptible group of Old World monkeys (158R). In the case of the phylogenetically more distant New World monkey Ntcps amino acid 158 plays a significant, but not exclusive role.

African green monkey TRIM5α restriction in simian immunodeficiency virus-specific rhesus macaque effector CD4 T cells enhances their survival and antiviral function.

UNLABELLED: The expression of xenogeneic TRIM5α proteins can restrict infection in various retrovirus/host cell pairings. Previously, we have shown that African green monkey TRIM5α (AgmTRIM5α) potently restricts both human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus mac239 (SIV(mac239)) replication in a transformed human T-cell line (L. V. Coren, et al., Retrovirology 12:11, 2015, http://dx.doi.org/10.1186/s12977-015-0137-9). To assess AgmTRIM5α restriction in primary cells, we transduced AgmTRIM5α into primary rhesus macaque CD4 T cells and infected them with SIV(mac239). Experiments with T-cell clones revealed that AgmTRIM5α could reproducibly restrict SIV(mac239) replication, and that this restriction synergizes with an intrinsic resistance to infection present in some CD4 T-cell clones. AgmTRIM5α transduction of virus-specific CD4 T-cell clones increased and prolonged their ability to suppress SIV spread in CD4 target cells. This increased antiviral function was strongly linked to decreased viral replication in the AgmTRIM5α-expressing effectors, consistent with restriction preventing the virus-induced cytopathogenicity that disables effector function. Taken together, our data show that AgmTRIM5α restriction, although not absolute, reduces SIV replication in primary rhesus CD4 T cells which, in turn, increases their antiviral function. These results support prior in vivo data indicating that the contribution of virus-specific CD4 T-cell effectors to viral control is limited due to infection. IMPORTANCE: The potential of effector CD4 T cells to immunologically modulate SIV/HIV infection likely is limited by their susceptibility to infection and subsequent inactivation or elimination. Here, we show that AgmTRIM5α expression inhibits SIV spread in primary effector CD4 T cells in vitro. Importantly, protection of effector CD4 T cells by AgmTRIM5α markedly enhanced their antiviral function by delaying SIV infection, thereby extending their viability despite the presence of virus. Our in vitro data support prior in vivo HIV-1 studies suggesting that the antiviral CD4 effector response is impaired due to infection and subsequent cytopathogenicity. The ability of AgmTRIM5α expression to restrict SIV infection in primary rhesus effector CD4 T cells now opens an opportunity to use the SIV/rhesus macaque model to further elucidate the potential and scope of anti-AIDS virus effector CD4 T-cell function.

Long-term artificial selection reveals a role of TCTP in autophagy in mammalian cells.

Understanding genomic variation and detecting selection signatures in a genome under selection have been great challenges for a century. Activation, development/exhaustion of primordial follicles in mammalian ovary determines reproductive success, menopause/end of female reproductive life. However, molecular mechanisms underlying oogenesis, particularly under artificial selection, are largely unknown. We report that a proteome-wide scan for selection signatures in the genome over 9,000 years of artificial pressure on the ovary revealed a general picture of selection signatures in the genome, especially genomic variations through artificial selection were detected in promoter and intron regions. Crossbreeding between domestic and wild species results in more than half of the protein spots exhibiting heterosis. Translationally controlled tumor protein (TCTP) is upregulated by artificial selection and positively regulates autophagy through the AMP-activated protein kinase pathway. Notably, TCTP interacts with ATG16 complex. In addition to cytoplasmic autophagy, nucleophagy occurs in the nuclei of granulosa and cumulus cells in ovaries, indicating an importance of the nuclear material for degradation by nucleophagy. Our findings provide insight into cellular and molecular mechanisms relevant for improvement of ovary functions, and identify selection signatures in the genome for ovary function over long-term artificial selection pressure.

Analysis of prostate-specific antigen transcripts in chimpanzees, cynomolgus monkeys, baboons, and African green monkeys.

The function of prostate-specific antigen (PSA) is to liquefy the semen coagulum so that the released sperm can fuse with the ovum. Fifteen spliced variants of the PSA gene have been reported in humans, but little is known about alternative splicing in nonhuman primates. Positive selection has been reported in sex- and reproductive-related genes from sea urchins to Drosophila to humans; however, there are few studies of adaptive evolution of the PSA gene. Here, using polymerase chain reaction (PCR) product cloning and sequencing, we study PSA transcript variant heterogeneity in the prostates of chimpanzees (Pan troglodytes), cynomolgus monkeys (Macaca fascicularis), baboons (Papio hamadryas anubis), and African green monkeys (Chlorocebus aethiops). Six PSA variants were identified in the chimpanzee prostate, but only two variants were found in cynomolgus monkeys, baboons, and African green monkeys. In the chimpanzee the full-length transcript is expressed at the same magnitude as the transcripts that retain intron 3. We have found previously unidentified splice variants of the PSA gene, some of which might be linked to disease conditions. Selection on the PSA gene was studied in 11 primate species by computational methods using the sequences reported here for African green monkey, cynomolgus monkey, baboon, and chimpanzee and other sequences available in public databases. A codon-based analysis (dN/dS) of the PSA gene identified potential adaptive evolution at five residue sites (Arg45, Lys70, Gln144, Pro189, and Thr203).

BRCA2 phosphorylated by PLK1 moves to the midbody to regulate cytokinesis mediated by nonmuscle myosin IIC.

Cytokinesis is the critical final step in cell division. BRCA2 disruption during cytokinesis is associated with chromosome instability, but mechanistic information is lacking that could be used to prevent cancer cell division. In this study, we report that BRCA2 phosphorylation by the mitotic polo-like kinase (PLK1) governs the localization of BRCA2 to the Flemming body at the central midbody, permitting an interaction with nonmuscle myosin IIC (NM-IIC). Formation of an NM-IIC ring-like structure at the Flemming body shows that the IIC-ring relies on its ATPase activity stimulated by interaction with BRCA2 and associated proteins. Notably, inhibiting this binding inactivated the ATPase activity, causing disassembly of the IIC-ring, defective formation of the midbody, and interruption of cytokinesis. An analysis of cancer-associated mutations in BRCA2 at the PLK1-binding site suggests that they may contribute to cytokinetic defects by altering BRCA2 localization. Our findings suggest that BRCA2-dependent IIC-ring formation is a critical step in proper formation of the midbody, offering an explanation for how chromosome instability may arise in breast cancer.

Nonhuman transferrin receptor 1 is an efficient cell entry receptor for Ocozocoautla de Espinosa virus.

Ocozocoautla de Espinosa virus (OCEV) is a novel, uncultured arenavirus. We found that the OCEV glycoprotein mediates entry into grivet and bat cells through transferrin receptor 1 (TfR1) binding but that OCEV glycoprotein precursor (GPC)-pseudotyped retroviruses poorly entered 53 human cancer cell lines. Interestingly, OCEV and Tacaribe virus could use bat, but not human, TfR1. Replacing three human TfR1 amino acids with their bat ortholog counterparts transformed human TfR1 into an efficient OCEV and Tacaribe virus receptor.

Effects of pathogenic proline mutations on myosin assembly.

Laing distal myopathy (MPD1) is a genetically dominant myopathy characterized by early and selective weakness of the distal muscles. Mutations in the MYH7 gene encoding for the ß-myosin heavy chain are the underlying genetic cause of MPD1. However, their pathogenic mechanisms are currently unknown. Here, we measure the biological effects of the R1500P and L1706P MPD1 mutations in different cellular systems. We show that, while the two mutations inhibit myosin self-assembly in non-muscle cells, they do not prevent incorporation of the mutant myosin into sarcomeres. Nevertheless, we find that the L1706P mutation affects proper antiparallel myosin association by accumulating in the bare zone of the sarcomere. Furthermore, bimolecular fluorescence complementation assay shows that the α-helix containing the R1500P mutation folds into homodimeric (mutant/mutant) and heterodimeric [mutant/wild type (WT)] myosin molecules that are competent for sarcomere incorporation. Both mutations also form aggregates consisting of cytoplasmic vacuoles surrounding paracrystalline arrays and amorphous rod-like inclusions that sequester WT myosin. Myosin aggregates were also detected in transgenic nematodes expressing the R1500P mutation. By showing that the two MPD1 mutations can have dominant effects on distinct components of the contractile apparatus, our data provide the first insights into the pathogenesis of the disease.

Aged vervet monkeys developing transthyretin amyloidosis with the human disease-causing Ile122 allele: a valid pathological model of the human disease.

Mutant forms of transthyretin (TTR) cause the most common type of autosomal-dominant hereditary systemic amyloidosis. In addition, wild-type TTR causes senile systemic amyloidosis, a sporadic disease seen in the elderly. Although spontaneous development of TTR amyloidosis had not been reported in animals other than humans, we recently determined that two aged vervet monkeys (Chlorocebus pygerythrus) spontaneously developed systemic TTR amyloidosis. In this study here, we first determined that aged vervet monkeys developed TTR amyloidosis and showed cardiac dysfunction but other primates did not. We also found that vervet monkeys had the TTR Ile122 allele, which is well known as a frequent mutation-causing human TTR amyloidosis. Furthermore, we generated recombinant monkey TTRs and determined that the vervet monkey TTR had lower tetrameric stability and formed more amyloid fibrils than did cynomolgus monkey TTR, which had the Val122 allele. We thus propose that the Ile122 allele has an important role in TTR amyloidosis in the aged vervet monkey and that this monkey can serve as a valid pathological model of the human disease. Finally, from the viewpoint of molecular evolution of TTR in primates, we determined that human TTR mutations causing the leptomeningeal phenotype of TTR amyloidosis tended to occur in amino acid residues that showed no diversity throughout primate evolution. Those findings may be valuable for understanding the genotype-phenotype correlation in this inherited human disease.

Single-nucleotide polymorphisms in the TNF gene are associated with obesity-related phenotypes in vervet monkeys.

Tumor necrosis factor (TNF) promoter single-nucleotide polymorphisms (SNPs) have been extensively characterized in humans, with numerous reports of associations with obesity-related phenotypes as well an array of infectious, immune-mediated, and inflammatory disease phenotypes. Controlling for the multitude of environmental risk factors in human studies has been a major confounder of efforts to elucidate the role and relative contribution of TNF promoter SNPs. As part of an ongoing initiative to further genetically and phenotypically characterize the St Kitts-origin vervet monkey (Chlorocebus aethiops ssp.) as an animal model of human obesity, we have conducted association analyses between TNF SNPs and previously defined obesity-related phenotypes in 265 pedigreed vervets. We report eight SNPs (-809G, -756A, -352C, -322A, +1285T, +2133T, +2362A, +2405), all contained within the same haplotype block and comprising a single haplotype, to be significantly associated with BMI, waist circumference, total plasma cholesterol (P < 0.05), and high-density lipoprotein-cholesterol (HDL-C) (P < 0.01). This study provides additional validation of the St Kitts-origin vervet model of obesity by demonstrating genetic associations analogous to that shown in humans.

A challenge to the ancient origin of SIVagm based on African green monkey mitochondrial genomes.

While the circumstances surrounding the origin and spread of HIV are becoming clearer, the particulars of the origin of simian immunodeficiency virus (SIV) are still unknown. Specifically, the age of SIV, whether it is an ancient or recent infection, has not been resolved. Although many instances of cross-species transmission of SIV have been documented, the similarity between the African green monkey (AGM) and SIVagm phylogenies has long been held as suggestive of ancient codivergence between SIVs and their primate hosts. Here, we present well-resolved phylogenies based on full-length AGM mitochondrial genomes and seven previously published SIVagm genomes; these allowed us to perform the first rigorous phylogenetic test to our knowledge of the hypothesis that SIVagm codiverged with the AGMs. Using the Shimodaira-Hasegawa test, we show that the AGM mitochondrial genomes and SIVagm did not evolve along the same topology. Furthermore, we demonstrate that the SIVagm topology can be explained by a pattern of west-to-east transmission of the virus across existing AGM geographic ranges. Using a relaxed molecular clock, we also provide a date for the most recent common ancestor of the AGMs at approximately 3 million years ago. This study substantially weakens the theory of ancient SIV infection followed by codivergence with its primate hosts.

[The short form of heparin-binding EGF-like growth factor. Part II].

The structure of monkey (Chlorocebus aethiops) heparin-binding EGF-like growth factor (HB-EGF) gene has been investigated in this work in comparison with the known structure of human gene. It was shown that HB-EGF short form (SF-HB-EGF) specific exon 3a is mapped between exons 3 and 4 at distance 700 b.p. from exon 4. In a number of human and simian cell lines the main part of SF-HB-EGF mRNA does not contain HB-EGF mRNA specific exons 4 and 5. In comparison with HB-EGF mRNA in SF-HB-EGF mRNA P-form, but not L-form of is predominant, and this mRNA encodes a polypeptide with changed propeptide structure. Labeled SF-HB-EGF competes with HB-EGF and EGF for binding sites at A431 cell surface, which may be due to interaction with specific receptor. All the data suggest a specific role of SF-HB-EGF in cellular signalization.

Phenotype and function of myeloid dendritic cells derived from African green monkey blood monocytes.

Myeloid dendritic cells probably play an important role in the immune response against HIV and SIV, and in the enhancement of CD4+ T cell infection. Here, we have investigated phenotypic and functional features of myeloid monocyte-derived DC (MDDC) from African green monkeys (AGMs). AGMs are natural hosts of SIV and exhibit no signs of abnormal T cell activation despite high SIV plasma viremia. We identified mAbs that cross-react specifically with homologous molecules expressed on AGM DC. We adapted a protocol to derive AGM MDDC by culture in the presence of GM-CSF and IL-4. The differentiated cells possessed a typical dendritic morphology and the majority were CD11c+ DC-SIGN+. AGM MDDC displayed a high expression of typical maturation markers, such as CD83, CD86 and DC-LAMP, and moderate immunostimulatory capacity, suggesting that the cells were in a semi-mature state. Stimulation resulted in further maturation, as shown by up-regulation of CD80 and decrease of endocytosis ability. However, neither increase of HLA-DR or CD40 expression nor enhanced immunostimulatory capacity was observed. The latter was associated with a low pro-inflammatory cytokine production during mixed lymphocyte reactions and a cytokine balance in favour of IL-10 in contrast to human MDDC. This is the first characterization of AGM MDDC. The tools described here are a crucial step for future studies in vivo or in vitro on the function of myeloid DC using the AGM animal model.

Palindromic AT-rich repeat in the NF1 gene is hypervariable in humans and evolutionarily conserved in primates.

Palindromic sequences are dispersed in the human genome and may cause chromosomal translocations in humans. They constitute unsequenced gaps in the human genome because of their resistance to PCR amplification, cloning into vectors, and sequencing. We have overcome these difficulties by using a combination of optimized PCR conditions, cloning in a recombination-deficient E. coli strain, and RNA polymerases in sequencing. Using these methods, we analyzed a palindromic AT-rich repeat (PATRR) in the neurofibromatosis type 1 (NF1) gene on chromosome 17 (17PATRR). The 17PATRR manifests a size polymorphism due to a highly variable length of (AT)(n) dinucleotide repeats within the PATRR. 17PATRRs can be categorized into two types: a longer one that comprises a nearly or completely perfect palindrome, and a shorter one that represents its deleted asymmetric derivative. In vitro analysis shows that the longer 17PATRR is more likely to form a cruciform structure than the shorter one. Two reported t(17;22)(q11;q11) patients with NF1, whose breakpoints were identified within the 17PATRR, have translocations that are derived from perfect or nearly perfect palindromic alleles. This implies that the symmetric structure of a PATRR can induce a translocation. We identified conserved PATRRs within the NF1 gene in great apes and similar inverted repeats in two Old World monkeys, but not in New World monkeys or other mammals. This indicates that the palindromic region appeared approximately 25 million years ago and elongated during primate evolution. Although such palindromic regions are usually unstable and disappear rapidly due to deletion, the 17PATRR in the NF1 gene was stably conserved during evolution for reasons that are still unknown.

The human and African green monkey TRIM5alpha genes encode Ref1 and Lv1 retroviral restriction factor activities.

The rhesus macaque tripartite motif containing protein TRIM5alpha specifically restricts HIV-1 infection at an early post-entry step before reverse transcription [Stremlau, M., Owens, C. M., Perron, M. J., Kiessling, M., Autissier, P. & Sodroski, J. (2004) Nature 427, 848-853]. Here, we show that the human and African green monkey (AGM) TRIM5alpha genes encode Ref1 and Lv1 antiretroviral activities, respectively. Expression of TRIM5alpha in permissive cat cells renders them resistant to restriction-sensitive murine leukemia virus but not closely related insensitive virus. Disruption of TRIM5alpha expression in human and AGM cells with small interfering RNA rescues infectivity of restricted virus without affecting unrestricted virus. We also demonstrate that the activity of the murine restriction factor Fv1 depends on TRIM5alpha expression when Fv1 is expressed in human cells. Furthermore, a drug that modifies the behavior of the related promyelocytic leukemia protein PML specifically rescues infection by viruses restricted by human TRIM5alpha. Alignment of the TRIM5alpha proteins from rhesus macaque and AGM indicates an 18-aa insertion. We speculate that this insertion may contribute to the broader specificity of the AGM TRIM5alpha restriction as compared with the human and rhesus macaque proteins.

Evolutionary and functional relationships within the DJ1 superfamily.

BACKGROUND: Inferences about protein function are often made based on sequence homology to other gene products of known activities. This approach is valuable for small families of conserved proteins but can be difficult to apply to large superfamilies of proteins with diverse function. In this study we looked at sequence homology between members of the DJ-1/ThiJ/PfpI superfamily, which includes a human protein of unclear function, DJ-1, associated with inherited Parkinson's disease. RESULTS: DJ-1 orthologs in a variety of eukaryotic species cluster together in a single group. The most closely related group is the bacterial ThiJ genes. These are kinases involved in the biosynthesis of thiamine, a function that has been dispensed with evolutionarily in most eukaryotes where thiamine is an essential nutrient. The similarity with other characterized members of the superfamily, including proteases, is more remote. This is congruent with the recently solved crystal structures that fail to demonstrate the presence of a catalytic triad required for protease activity. CONCLUSION: DJ-1 may have evolved from the bacterial gene encoding ThiJ kinase. However, as this function has been dispensed with in eukaryotes it appears that the gene has been co-opted for another function.

A single amino acid of APOBEC3G controls its species-specific interaction with virion infectivity factor (Vif).

The virion infectivity factor (Vif) accessory protein of HIV-1 forms a complex with the cellular cytidine deaminase APOBEC3G (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G) to block its antiviral activity. The antiviral property of APOBEC3G is conserved in several mammalian species, but the ability of Vif to block this activity is species-specific. HIV-1 Vif blocks human APOBEC3G but does not block the mouse or African green monkey (AGM) enzyme. Conversely, SIV(AGM) Vif blocks the antiviral activity of AGM but not human APOBEC3G. We demonstrate that the species specificity is caused by a single amino acid difference in APOBEC3G. Replacement of Asp-128 in human APOBEC3G with the Lys-128 of AGM APOBEC3G caused the enzyme to switch its interaction, becoming sensitive to SIV(AGM) Vif and resistant to HIV-1 Vif. Conversely, the reciprocal Lys to Asp switch in AGM APOBEC3G reversed its specificity for Vif. The reversal of biological activity was accompanied by the corresponding switch in the species specificity with which the enzyme physically associated with Vif and was excluded from virions. The charge of the amino acid at position 128 was a critical determinant of species specificity. Based on the crystal structure of the distantly related Escherichia coli cytidine deaminase, we propose that this amino acid is positioned on a solvent-exposed loop of APOBEC3G on the same face of the protein as the catalytic site.

Sustained high-yield production of recombinant proteins in transiently transfected COS-7 cells grown on trimethylamine-coated (hillex) microcarrier beads.

The present study shows that COS-7 cells transiently transfected and maintained on positively charged (trimethylamine-coated) microcarrier beads synthesize recombinant protein at higher levels and for longer periods of time than cells transfected and maintained on polystyrene flasks in monolayer culture. Sustained, high-level synthesis was observed with secreted chimeric proteins (murine E-selectin- and P-selectin-human IgM chimeras) and a secreted hematopoietic growth factor (granulocyte-macrophage colony-stimulating factor). Studies with green fluorescent protein indicated that the transfected cells attached more firmly to the trimethylamine-coated microcarriers than to polystyrene flasks. After 10-14 days in culture, most of the transfected cells detached from the surface of the polystyrene flasks, whereas most transfected cells remained attached to the microcarriers. The transiently transfected microcarrier cultures produced higher levels of protein per transfected cell due to this prolonged attachment. The prolonged attachment and higher output of transfected cells on microcarriers resulted in a 5-fold increase in protein production from a single transfection over two weeks. Thus, microcarrier-based transient transfection yields quantities of recombinant proteins with a significant savings of time and reagents over monolayer culture.

Trafficking of Na,K-ATPase fused to enhanced green fluorescent protein is mediated by protein kinase A or C.

Fusion of enhanced green fluorescent protein (EGFP) to the C-terminal of rat Na,K-ATPase a1-subunit is introduced as a novel procedure for visualizing trafficking of Na,K-pumps in living COS-1 renal cells in response to PKA or PKC stimulation. Stable, functional expression of the fluorescent chimera (Na,K-EGFP) was achieved in COS-1 cells using combined puromycin and ouabain selection procedures. Na,K-pump activities were unchanged after fusion with EGFP, both in basal and regulated states. In confocal laser scanning and fluorescence microscopes, the Na,K-EGFP chimera was distributed mainly along the plasma membrane of COS cells. In unstimulated COS cells, Na,K-EGFP was also present in lysosomes and in vesicles en route from the endoplasmic reticulum to the plasma membrane, but it was almost absent from recycling endosomes labelled with fluorescent transferrin. After activation of protein kinase A or C, the density of co-localizing Na,K-EGFP and transferrin vesicles was increased 3-4-fold, while the ouabain-sensitive 86Rb uptake was reduced by 22%. Simultaneous activation of PKA and PKC had additive effects with a 6-fold increase of co-localization and a 38% reduction of 86Rb uptake. Responses of similar magnitude were seen after inhibition of protein phosphatase by okadaic acid. Reduction of the amount of Na,K-ATPase in surface plasma membranes through internalization in recycling endosomes may thus in part explain a decrease in Na,K-pump activity following protein kinase activation or protein phosphatase inhibition.

The carcinoembryonic antigen (CEA) gene family in non-human primates.

Carcinoembryonic antigen (CEA) is a tumor marker of wide clinical use though its function remains unknown. The CEA counterpart and some related macromolecules cannot be demonstrated in mice, thus prohibiting studies of CEA function by gene disruption strategies. In an attempt to find a relevant animal model for functional studies of CEA we have investigated the occurrence of CEA subgroup members in baboon and African green monkey at the genomic and mRNA levels. The investigation was focused on the characteristic immunoglobulin-variable region-like (IgV-like) N-terminal domain of the family members. Based on N-domain sequences 3 and 4 different CEA subgroup genes, respectively, were identified. One sequence in each monkey species corresponded to human CEACAM8, while it was not possible to assign an obvious human counterpart for the other N-domain sequences. However, studies of cDNAs from African green monkey COS-1 cells identified one of the sequences as CEACAM1. Expression of CEACAM1 mRNA and protein was upregulated by IFNgamma as has previously been demonstrated for human CEACAM1. Presence of GPI-linked CEA subgroup members in African green monkey was suggested by sequencing. Both monkey species would thus seem suitable for functional studies of selected CEA subgroup members.