Prp (proline-rich protein) genes linked to markers Es-12 (esterase-12), Ea-10 (erythrocyte alloantigen), and loci on distal mouse chromosome 6

Transfusion of murine red blood cells expressing the human KEL glycoprotein induces clinically significant alloantibodies

BACKGROUND

Red blood cell (RBC) alloantibodies to nonself antigens may develop after transfusion or pregnancy, leading to morbidity and mortality in the form of hemolytic transfusion reactions or hemolytic disease of the newborn. A better understanding of the mechanisms of RBC alloantibody induction, or strategies to mitigate the consequences of such antibodies, may ultimately improve transfusion safety. However, such studies are inherently difficult in humans.

STUDY DESIGN AND METHODS

We recently generated transgenic mice with RBC-specific expression of the human KEL glycoprotein, specifically the KEL2 or KEL1 antigens. Herein, we investigate recipient alloimmune responses to transfused RBCs in this system.

RESULTS

Transfusion of RBCs from KEL2 donors into wild-type recipients (lacking the human KEL protein but expressing the murine KEL ortholog) resulted in dose-dependent anti-KEL glycoprotein immunoglobulin (Ig)M and IgG antibody responses, enhanced by recipient inflammation with poly(I:C). Boostable responses were evident upon repeat transfusion, with morbid-appearing alloimmunized recipients experiencing rapid clearance of transfused KEL2 but not control RBCs. Although KEL1 RBCs were also immunogenic after transfusion into wild-type recipients, transfusion of KEL1 RBCs into KEL2 recipients or vice versa failed to lead to detectable anti-KEL1 or anti-KEL2 responses.

CONCLUSIONS

This murine model, with reproducible and clinically significant KEL glycoprotein alloantibody responses, provides a platform for future mechanistic studies of RBC alloantibody induction and consequences. Long-term translational goals of these studies include improving transfusion safety for at-risk patients.

Responsiveness to 6-n-propylthiouracil (PROP) is associated with salivary levels of two specific basic proline-rich proteins in humans

Thiourea tasting can be predictive of individual differences in bitter taste responses, general food preferences and eating behavior, and could be correlated with saliva chemical composition. We investigated the possible relationship between PROP bitter taste responsiveness and the salivary proteome in subjects genotyped for TAS2R38 and gustin gene polymorphisms. Taste perception intensity evoked by PROP and NaCl solutions was measured in sixty-three volunteers (21 males, 42 females, age 25±3 y) to establish their PROP taster status, and 24 PROP super-tasters and 21 nontasters were selected to participate in the study. TAS2R38 and gustin gene molecular analysis were performed using PCR techniques. Qualitative and quantitative determination of salivary proteins was performed by HPLC-ESI-MS before and after PROP taste stimulation. PROP super-tastings was strongly associated with the 'taster' variant (PAV haplotype) of TAS2R38 and the A allele of rs2274333 polymorphism in the gustin gene and nontasting was associated with the minor alleles at both loci. ANOVA revealed that basal levels of II-2 and Ps-1 proteins, belonging to the basic proline-rich protein (bPRPs) family, were significantly higher in PROP super-taster than in nontaster un-stimulated saliva, and that PROP stimulation elicited a rapid increase in the levels of these same proteins only in PROP super-taster saliva. These data show for the first time that responsiveness to PROP is associated with salivary levels of II-2 peptide and Ps-1 protein, which are products of the PRB1 gene. These findings suggest that PRB1, in addition to TAS2R38 and gustin, could contribute to individual differences in thiourea sensitivity, and the expression of the PROP phenotype as a complex genetic trait.

Lessons learned from mouse models of hemolytic transfusion reactions

PURPOSE OF REVIEW

Hemolytic transfusion reactions (HTRs) are potentially fatal complications of blood transfusions. Many studies, primarily performed in vitro, have provided a great deal of insight into the initiating events of HTRs; however, it is not clear how they are modulated and how they combine to lead to one or more of the final common pathways. Recently developed mouse HTR models now make it possible to enhance our understanding of the pathogenesis of HTRs; this will allow for the rational design of specific therapies to prevent or ameliorate this serious complication in transfusion medicine.

RECENT FINDINGS

Mouse models support the hypothesis that 'cytokine storm' plays an important role in the pathogenesis of HTRs. Nitric oxide and endothelial cell dysfunction are also implicated in the pathophysiology of these reactions. In addition, the intriguing phenomenon of 'antigen loss,' in which antigen crosslinking by alloantibody leads to antigen removal rather than red blood cell clearance, has been modeled and explored. Finally, these mouse models were used to evaluate new therapeutic targets employing complement receptor 1 peptide homologues and the antimacrophage agent, liposomal clodronate.

SUMMARY

Models of HTRs are valuable for gaining a better understanding of the pathophysiology of these potentially fatal complications of blood transfusion. The participation of various inflammatory mediators was shown to play a role in these reactions in vivo. This knowledge will lead to novel treatment options.

Inbred mouse strains C57BL/6J and DBA/2J vary in sensitivity to a subset of bitter stimuli

Background

Common inbred mouse strains are genotypically diverse, but it is still poorly understood how this diversity relates to specific differences in behavior. To identify quantitative trait genes that influence taste behavior differences, it is critical to utilize assays that exclusively measure the contribution of orosensory cues. With a few exceptions, previous characterizations of behavioral taste sensitivity in inbred mouse strains have generally measured consumption, which can be confounded by post-ingestive effects. Here, we used a taste-salient brief-access procedure to measure taste sensitivity to eight stimuli characterized as bitter or aversive in C57BL/6J (B6) and DBA/2J (D2) mice.

Results

B6 mice were more sensitive than D2 mice to a subset of bitter stimuli, including quinine hydrochloride (QHCl), 6-n-propylthiouracil (PROP), and MgCl₂. D2 mice were more sensitive than B6 mice to the bitter stimulus raffinose undecaacetate (RUA). These strains did not differ in sensitivity to cycloheximide (CYX), denatonium benzoate (DB), KCl or HCl.

Conclusion

B6-D2 taste sensitivity differences indicate that differences in consumption of QHCl, PROP, MgCl₂ and RUA are based on immediate orosensory cues, not post-ingestive effects. The absence of a strain difference for CYX suggests that polymorphisms in a T2R-type taste receptor shown to be differentially sensitive to CYX in vitro are unlikely to differentially contribute to the CYX behavioral response in vivo. The results of these studies point to the utility of these common mouse strains and their associated resources for investigation into the genetic mechanisms of taste.

Codominant expression of genes coding for different sets of inducible salivary polypeptides associated with parotid hypertrophy in two inbred mouse strains

Experimental mouse parotid hypertrophy has been associated with the expression of a number of isoproterenol-induced salivary proline-rich polypeptides (IISPs). Mouse salivary proline-rich proteins (PRPs) have been mapped both to chromosomes 6 and 8. Recently, mice of two inbred strains (A/Snell and A. Swiss) have been found to differ drastically in the IISPs. In this study, mice of both strains were used for cross-breeding experiments addressed to define the pattern of inheritance of the IISP phenotype and to establish whether the IISPs are coded on a single or on several chromosomes. The IISP phenotype of individual mice was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole saliva collected after three daily stimulations by isoproterenol. Parental A/Snell and A. Swiss mice were homogeneous for distinctive strain-associated IISP-patterns. First filial generation (F1) mice obtained from the cross of A/Snell with A. Swiss mice expressed with no exception both the A/Snell and A. Swiss IISPs (coexpression). In the second filial generation (F2) both parental IISP phenotypes reappeared together with a majority of mice expressing the F1-hybrid phenotype (1:2:1 ratio). Backcrosses of F1 x A/Snell and F1 x A. Swiss produced offsprings displaying the F1 and the corresponding parental phenotypes with a 1:1 ratio. No recombinants were observed among F2 mice or among mice resulting from backcrosses. Thus, genes coding for the IISPs that are expressed differentially in both mouse strains are located on the same chromosome, probably at the same locus (alleles) or at quite closely linked loci (nonalleles).

Role of saliva in the maintenance of taste sensitivity

Saliva is the principal fluid component of the external environment of the taste receptor cells and, as such, could play a role in taste sensitivity. Its main role includes transport of taste substances to and protection of the taste receptor. In the initial process of taste perception, saliva acts as a solvent for taste substances; salivary water dissolves taste substances, and the latter diffuse to the taste receptor sites. During this process, some salivary constituents chemically interact with taste substances. For example, salivary buffers (e.g., bicarbonate ions) decrease the concentration of free hydrogen ions (sour taste), and there are some salivary proteins which may bind with bitter taste substances. Another effect of saliva on taste transduction is that some salivary constituents can continuously stimulate the taste receptor, resulting in an alteration of taste sensitivity. For example, the taste detection threshold for NaCl is slightly above the salivary sodium concentrations with which the taste receptor is continuously stimulated. In contrast, saliva protects the taste receptor from damage brought about by dryness and bacterial infection, and from disuse atrophy via a decrease in transport of taste stimuli to the receptor sites. This is a long-term effect of saliva that may be related to taste disorders. These various effects of saliva on the taste perception differ depending on the anatomical relationship between the taste buds and oral openings of the ducts of the salivary glands. Many taste buds are localized in the trenches of the foliate and circumvallate papillae, where the lingual minor salivary glands (von Ebner's glands) secrete saliva. Taste buds situated at the surface of the anterior part of the tongue and soft palate are bathed with the mixed saliva secreted mainly by the three major salivary glands.

High-resolution genetic mapping of the sucrose octaacetate taste aversion (Soa) locus on mouse Chromosome 6

An acetylated sugar, sucrose octaacetate (SOA), tastes bitter to humans and has an aversive taste to at least some mice and other animals. In mice, taste aversion to SOA depends on allelic variation of a single locus, Soa. Three Soa alleles determine 'taster' (Soa(a)), 'nontaster' (Soa(b)), and 'demitaster' (Soa(c)) phenotypes of taste sensitivity to SOA. Although Soa has been mapped to distal Chromosome (Chr) 6, the limits of the Soa region have not been defined. In this study, mice from congenic strains SW.B6-Soa(b), B6.SW-Soa(a), and C3.SW-Soa(a/c) and from an outbred CFW strain were genotyped with polymorphic markers on Chr 6. In the congenic strains, the limits of introgressed donor fragments were determined. In the outbred mice, linkage disequilibrium and haplotype analyses were conducted. Positions of the markers were further resolved by using radiation hybrid mapping. The results show that the Soa locus is contained in an approximately 1-cM (3.3-4.9 Mb) region including the Prp locus.

Quantitative trait loci for acute behavioral sensitivity to paraoxon

Genetic mechanisms responsible for organophosphate (OP)-induced behavioral changes remain obscure. In the present study, provisional quantitative trait loci (QTL) associated with acute sensitivity or insensitivity to hypolocomotion produced by the OP paraoxon were identified. Naive adult male and female mice of the BXD/Ty series (22 different BXD strains plus C57BL/6J and DBA/2J progenitor strains) received 0 or 0.25 mg/kg paraoxon (IP), immediately before placement in an activity chamber for a 30-min test. As expected, based on dose-response and time course studies with Swiss-Webster, C57BL/6, and DBA/2 mice, paraoxon treatment reduced locomotor activity in most, but not all BXD strains. Heritability (proportion of phenotypic variability attributed to genetic differences) was 0. 58 for the paraoxon treatment effect. Difference scores (strain mean for vehicle activity minus strain mean for paraoxon activity), and percent change in activity of paraoxon-treated mice compared to vehicle-treated mice were calculated for each BXD strain. QTL analyses using activity difference scores and percentage change in activity were conducted using a database with over 1300 unique genetic markers. Several provisional QTL found on different chromosomes were associated with the activity phenotype. Of these, several markers attained p<0.01 or greater. These were as follows: Chr 1: Ly9, p<0.006; Chr 6: D6Ncvs44, p<0.0005; Chr 9: D9Mit15, p<0. 003; Chr 11: D11Ncvs76, p<0.002; Chr 15: Tstap198, p<0.008. In addition, several markers on chromosome 3 approached p<0.01. Identified genes found near these regions include two plasma carboxylesterase alleles on chromosomes 6 and 9, a glutamate receptor subtype on chromosome 11 and a glycine receptor subunit on chromosome 11, raising the possibility that these genes could be the basis for these provisional QTLs.

Localization on a Physical Map of the NKC-Linked Cmv1 Locus Between Ly49b and the Prp Gene Cluster on Mouse Chromosome 6

The Cmv1 locus controls NK cell-mediated resistance to infection with murine CMV. Our recent genetic analysis of backcross mice demonstrated that the NK gene complex (NKC)-linked Cmv1 locus should reside between the Ly49 and Prp gene clusters on distal mouse chromosome 6. We have aligned yeast artificial chromosome (YAC) inserts in a contig spanning the interval between the Ly49 and Prp gene clusters. This YAC contig includes 13 overlapping YAC inserts that span more than 2 megabases (Mb) in C57BL/6 (B6) mice. Since we have identified genomic clones that span the Ly49-Prp gene region, we hypothesize that at least one should contain the Cmv1 locus. To narrow the Cmv1 critical region, we developed novel NKC genetic markers and used these to genotype informative backcross and intra-NKC recombinant congenic mouse DNA samples. These data suggest that Cmv1 resides on a single YAC insert within an interval that corresponds to a physical distance of ∼390 kb. This high resolution, integrated physical and genetic NKC map will facilitate identification of Cmv1 and other NKC-linked loci that regulate NK cell-mediated immunity.

Chorda tympani responses in two inbred strains of mice with different taste preferences

Behavioral studies suggest that there are significant differences in the taste systems of the inbred mouse (Mus musculus) strains: C57BL/6J (B6) and DBA/2J (D2). In an attempt to understand the biological basis of the behavioral differences, we recorded whole-nerve chorda tympani responses to taste solutions and compared the results to intake of similar solutions in nondeprived mice. Stimuli included a test series composed of 0.1 M sodium chloride, 0.3 M sucrose, 10 mM sodium saccharin, 3 mM hydrochloric acid, and 3 mM quinine hydrochloride, as well as concentration series for the same substances. Neural activity of the chorda tympani that was evoked by sucrose, saccharin, or NaCl was greater in B6 than D2 mice; and neural threshold for sucrose was lower in B6 mice, but neural thresholds for HCl and quinine were lower in D2 mice. B6 mice drank more sucrose and saccharin but less quinine than D2 mice; thus, sucrose and saccharin preference were positively correlated, but NaCl and quinine aversiveness were negatively correlated with the chorda tympani results. Nonetheless, genes involved in the structuring of taste receptors and/or the chordae tympani, which transduce taste stimuli having diverse perceptual qualities, differ for the two mouse strains.

Genetic control of natural killing and in vivo tumor elimination by the Chok locus

The molecular mechanisms underlying target recognition during natural killing are not well understood. One approach to dissect the complexities of natural killer (NK) cell recognition is through exploitation of genetic differences among inbred mouse strains. In this study, we determined that interleukin 2-activated BALB/c-derived NK cells could not lyse Chinese hamster ovary (CHO) cells as efficiently as C57BL/6-derived NK cells, despite equivalent capacity to kill other targets. This strain-determined difference was also exhibited by freshly isolated NK cells, and was determined to be independent of host major histocompatibility haplotype. Furthermore, CHO killing did not correlate with expression of NK1.1 or 2B4 activation molecules. Genetic mapping studies revealed linkage between the locus influencing CHO killing, termed Chok, and loci encoded within the NK gene complex (NKC), suggesting that Chok encodes an NK cell receptor specific for CHO cells. In vivo assays recapitulated the in vitro data, and both studies determined that Chok regulates an NK perforin-dependent cytotoxic process. These results may have implications for the role of NK cells in xenograft rejection. Our genetic analysis suggests Chok is a single locus that affects NK cell-mediated cytotoxicity similar to other NKC loci that also regulate the complex activity of NK cells.

Proline-rich-protein promoters direct LacZ expression to the granular convoluted tubular cells of the submandibular gland in adult transgenic mice

The ability of two mouse PRP gene promoters to direct the expression of the bacterial lacZ reporter gene was tested in transgenic mice. Transgenes A1-lacZ and C1-lacZ consisted of 8.2 kb A1 and 7.8 kb C1 PRP promoters respectively fused to the lacZ coding sequence. A1 and C1 are two A-type PRP genes isolated from the inbred SWR mice, which show the same gene structure and similar sequence to the closely related MP2 and M14 PRP genes previously cloned from outbred CD-1 mice. We here show that both A1-lacZ and C1-lacZ transgenes have very similar expression patterns: (1) they expressed the lacZ gene in all 14 established transgenic lines under normal (non-stimulated) conditions; (2) the expression was restricted to the granular convoluted tubular cells of the submandibular glands; (3) the expression was developmentally regulated beginning at sexual maturation and lasting to at least 1.5 years of age; and (4) expression in some lines was probably influenced by sex hormones, since higher expression was found in males than in females. A1-lacZ and C1-lacZ are the first transgenes derived from the PRP/GRP (glutamine/glutamic acid-rich protein) gene superfamily to be expressed in the granular convoluted tubular cells (with known endocrine functions), rather than in the acinar cells (with mainly exocrine functions) of the submandibular glands.

The genetics of tasting in mice. VII. Glycine revisited, and the chromosomal location of Sac and Soa

Previous work which appeared to show that some strains of mice taste glycine solutions as bitter has been found to be in error. The bitterness came from copper glycinate which formed in the brass drinking spouts. Taste testing with copper glycinate shows that the genetical data identifying the gene Glb are still valid. The close linkage of Glb and Rua has been confirmed. Most strains of mice prefer glycine solution to water, presumably because the glycine tastes sweet. The degree of preference for glycine is correlated with the degree of preference for other sweet substances such as saccharin or acesulfame. The gene dpa appears not to be involved. The sweetness tasting gene Sac has been mapped to chromosome 4 at 8.1 +/- 3.4 cM distal to Nppa (formerly Pnd). The bitterness tasting gene Soa is very closely linked to Prp on chromosome 6 (no recombinants among 67 backcross progeny). It is suggested that the sweetness and bitterness tasting genes have descended from a common ancestral tasting gene which existed before the tetraploidization of the genome which took place in early vertebrate evolution.

Salivary proline-rich proteins: biochemistry, molecular biology, and regulation of expression

The proline-rich proteins (PRPs) in mammalian salivary glands are encoded by tissue-specific multigene families whose members have diverged with respect to structure and regulation of expression. PRPs are expressed constitutively in humans, and comprise about [70%] of the total salivary proteins. Families of similar proteins are dramatically increased or induced in parotid and submandibular glands of rats, mice and hamsters by treatment with the [beta-] agonist isoproterenol. Feeding tannins to rats and mice mimics the effects of isoproterenol on the parotid glands. Salivary PRPs may constitute a defense mechanism against tannins and other polyhydroxylated phenols ingested. Putative transcriptional regulatory sequences have been identified in mouse PRP genes.

Chromosome mapping of Soa, a gene influencing gustatory sensitivity to sucrose octaacetate in mice

Strain distribution patterns among recombinant inbred strains suggested that a locus influencing taste sensitivity to sucrose octaacetate was on chromosome 6. A location for Soa was established by linkage analysis of behavioral and electrophoretic data from outbred and congenic strains and from test-cross progeny. Haplotyping of 41 outbred CFW-Cr animals with a cDNA probe showed perfect cosegregation of Soa and Prp, a gene for salivary proline-rich proteins. Five of twelve B6.SW-Soaa strains were found to retain Ldr-1, lactate dehydrogenase regulator-1, on chromosome 6 as an allelic passenger from the SWR/J donor strain (source of the Soaa Taster allele). Centimorgan distance was estimated using the ABP/Le linkage-testing strain (non-Taster, Soab) and the SWR/J strain (Taster, Soaa) in a testcross breeding system. The data are consistent with a position for the Soa locus on mouse chromosome 6, 62 cM from the centromere.

Esterase-29 (ES-29): biochemical characterization and control by two independent gene loci of a testosterone-dependent mouse serum esterase

Biochemistry and genetics of a testosterone-dependent murine serum esterase designated esterase-29 (ES-29) are described. The enzyme was identified after disc electrophoresis and subsequent staining for esterase using alpha-naphthyl acetate as the substrate. It was inhibited by bis-p-nitrophenyl phosphate and was resistant to p-chlorophenylsulphonate and hence was classified as carboxylesterase EC3.1.1.1. The molecular mass was estimated to be about 130 kDa. It was shown that ES-29 is under the control of two independent genes. The first, termed Es-29, is suggested to be a structural locus, linked to the cluster-2 esterase loci on chromosome 8. Three alleles at Es-29, Es-29a, Es-29b, and Es-29c are distinguished, which determine absence (SEG/1), strong activity (BALB/cJ), and low activity (MOLH/Fre), respectively. The second locus, termed Mse-1 (serum esterase modifying factor), was found to be closely linked to Pre-2 on chromosome 12 and is suggested to be a modifying or regulatory gene. Two alleles were distinguished, Mse-1a (BALB/cJ) and Mse-1m (MOL3/JA, Cas-Bgr), which determine whether ES-29 appears as a single band or a double band, respectively. Mse-1m is dominant to Mse-1a.

Molecular genetic linkage maps of mouse chromosomes 4 and 6

We have generated a moderate resolution genetic map of mouse chromosomes 4 and 6 utilizing a (C57BL/6J x Mus spretus) F1 x Mus spretus backcross with RFLPs for 31 probes. The map for chromosome 4 covers 77 cM and details a large region of homology to human chromosome 1p. The map establishes the breakpoints in the mouse 4-human 1p region of homology to a 2-cM interval between Ifa and Jun in mouse and to the interval between JUN and ACADM in human. The map for mouse chromosome 6 spans a 65-cM region and contains a large region of homology to human 7q. These maps also provide chromosomal assignment and order for a number of previously unmapped probes. The maps should allow the rapid regional assignment of new markers to mouse chromosomes 4 and 6. In addition, knowledge of the gene order in mouse may prove useful in determining the gene order of the homologous regions in human.

mRNAs for PRPs, statherin, and histatins in von Ebner's gland tissues

A search was made for expression of genes for proline-rich proteins (PRPs) and other salivary-type proteins, including statherin and histatins, in taste-bud tissues of mice and primates because of previous genetic findings in mice (Azen et al., 1986) that Prp and taste genes for certain bitter substances are either the same or closely linked. Taste-bud tissues and other tissues were tested for specific mRNAs with labeled DNA probes by Northern blotting and in situ hybridization. It was found that PRP mRNAs were present in von Ebner's glands of mice and macaques, and that there was a much greater degree of PRP mRNA induction in mouse parotid (16-fold) than in von Ebner's gland (two-fold) after in vivo isoproterenol stimulation. This difference may be due, in part, to differences in autonomic nerve innervation. Statherin and histatin mRNAs were found in macaque taste-bud tissues containing von Ebner's gland, and statherin protein was found in human von Ebner's gland by immunohistochemistry. The finding of PRP gene expression in von Ebner's gland, whose secretions have been suggested to play a role in taste stimulation, adds further support to a possible function of PRPs in bitter tasting. The possible functions of statherin and histatins in von Ebner's gland secretions may be related to statherin's regulation of salivary calcium and histatins' antibacterial and antifungal properties.

Cmv-1, a genetic locus that controls murine cytomegalovirus replication in the spleen

The genetic basis of the control of acute splenic MCMV infection was studied after intraperitoneal inoculation of the virus. Classical Mendelian analyses using C57BL/6 (resistant) and BALB/c (susceptible) parental strains disclosed an autosomal dominant non-H-2 gene that regulates splenic virus replication. The probable location of this gene, to which we have assigned the symbol Cmv-1, is on chromosome 6 as defined by the strain distribution pattern of splenic MCMV replication in CXB recombinant inbred mice. Although there is a similar hierarchy of resistance to MCMV and HSV-1 with respect to the C57BL and BALB genetic backgrounds, the strain distribution pattern of HSV-1 replication in recombinant inbred mice suggests that Cmv-1 is not involved in restricting the spread of this virus. This is the first clear identification of a non-H-2 gene regulating the magnitude of MCMV infection. Elucidation of the function of this gene may be a fundamental step towards understanding the control of systemic CMV infection.