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PubMed2002

The yeast pafl-rNA polymerase II complex is required for full expression of a subset of cell cycle-regulated genes.

We have previously described an alternative form of RNA polymerase II in yeast lacking the Srb and Med proteins but including Pafl, Cdc73, Hprl, and Ccr4. The Pafl-RNA polymerase II complex (Paf1 complex) acts in the same pathway as the Pkc1-mitogen-activated protein kinase cascade and is required for full expression of many cell wall biosynthetic genes. The expression of several of these cell integrity genes, as well as many other Paf1-requiring genes identified by differential display and microarray analyses, is regulated during the cell cycle. To determine whether the Paf1 complex is required for basal or cyclic expression of these genes, we assayed transcript abundance throughout the cell cycle. We found that transcript abundance for a subset of cell cycle-regulated genes, including CLN1, HO, RNR1, and FAR1, is reduced from 2- to 13-fold in a paf1delta strain, but that this reduction is not promoter dependent. Despite the decreased expression levels, cyclic expression is still observed. We also examined the possibility that the Paf1 complex acts in the same pathway as either SBF (Swi4/Swi6) or MBF (Mbp1/Swi6), the partially redundant cell cycle transcription factors. Consistent with the possibility that they have overlapping essential functions, we found that loss of Paf1 is lethal in combination with loss of Swi4 or Swi6. In addition, overexpression of either Swi4 or Mbp1 suppresses some paf1delta phenotypes. These data establish that the Paf1 complex plays an important role in the essential regulatory pathway controlled by SBF and MBF.

Cell Cycle↗
PubMed1990

Sequence analysis and transcriptional organization of the Rhodopseudomonas viridis cytochrome c2 gene.

The cytochrome c2 gene (cycA) of the purple nonsulfur bacterium Rhodopseudomonas viridis was isolated from a genomic library by using two degenerate oligonucleotides containing all possible DNA sequences predicted from the published amino acid sequence of this protein (Ambler et al., Proc. Natl. Acad. Sci. USA 73:472-475, 1976). Cloning and sequence analysis of the cytochrome c2 gene indicated the presence of a typical procaryotic 20-residue signal peptide, suggesting that this periplasmic protein in synthesized in vivo as a precursor. In addition, four amino acids were found to be different by comparing the published sequence of the mature protein with that deduced from the isolated cycA gene (Lys-14----Leu, Ser-46----Ala, Ile-84----Val, Leu-97----Ile). Northern (RNA) blot analysis and fine mapping of the 5' and 3' ends of the cycA gene transcript from photoheterotrophically grown R. viridis cells revealed one abundant transcript of 523 to 530 nucleotides in length, with the transcription start site at position -39 relative to the coding region of cytochrome c2. A low-abundance transcript with an extended 3' end (about 600 bases in length) is thought to be processed by exonucleases, resulting in the slightly shorter main transcript.

Amino Acid Sequence↗
PubMed1985

Phytochrome control of specific mRNA levels in developing pea buds : the presence of both very low fluence and low fluence responses.

We have examined phytochrome regulated changes in transcript abundance for 11 different light regulated mRNAs in developing pea buds. Fluence-response curves were measured for changes in transcript abundance in response to red light pulses in both the low and very low fluence ranges. Most transcripts show only low fluence responses, with a threshold of approximately 10 micromoles per square meter. All of the low fluence responses are reversible by far red light. One transcript shows a very low fluence response, with a threshold of approximately 10(-4) micromoles per square meter. As expected, the very low fluence response is not far red reversible and in fact can be induced by far red light.Various fluences of red light were also used as pretreatments before transferring seedlings to continuous white light. One transcript responds to pretreatments in the very low fluence range, several respond to pretreatments in the low fluence range (including chlorophyll a/b binding protein RNA and ribulose-1,5-bisphosphate carboxylase RNA), and several show no response to the red light under these conditions. The threshold of these low fluence responses is approximately 10(2) micromoles per square meter, one order of magnitude greater than the threshold of the low fluence responses to red light alone.The transcripts may also be grouped by their responses to white light treatment alone. Three of the clones correspond to transcripts whose abundance decreases after a 24 hour white light treatment. The remainder of the mRNAs increase between 2- and 10-fold in response to the 24 hour white light.

Journal Article↗
PubMed2005

Cloning and characterization of the hsp70 multigene family from silver sea bream: Modulated gene expression between warm and cold temperature acclimation.

The genes encoding heat shock cognate 70 (hsc70) and inducible heat shock protein 70 (hsp70) were cloned and characterized from silver sea bream liver. Upon acute heat shock (+7 degrees C), the transcript abundance of hsc70 was increased 1.7-fold whereas the transcript abundance of hsp70 increased 6.7-fold. The chronic acclimation of sea bream to cold temperature (12 degrees C) resulted in a downregulation of hsc70 and an upregulation of hsp70 in comparison to levels in sea bream kept at a warmer temperature (25 degrees C). The expression of heat shock transcription factor I was also increased during cold temperature acclimation. Increased amounts of hepatic insulin-like growth factor 1 transcript, serum thyroxine (T4), and triiodothyronine (T3) were also found during cold temperature acclimation whereas serum cortisol remained unchanged. The results from this study demonstrate how temperature acclimation, in fish, can affect the regulation of the hsp70 multigene family and hormonal factors that are associated with anabolism.

Acclimatization↗
PubMed2004

Expression of PEG11 and PEG11AS transcripts in normal and callipyge sheep.

BACKGROUND: The callipyge mutation is located within an imprinted gene cluster on ovine chromosome 18. The callipyge trait exhibits polar overdominant inheritance due to the fact that only heterozygotes inheriting a mutant paternal allele (paternal heterozygotes) have a phenotype of muscle hypertrophy, reduced fat and a more compact skeleton. The mutation is a single A to G transition in an intergenic region that results in the increased expression of several genes within the imprinted cluster without changing their parent-of-origin allele-specific expression. RESULTS: There was a significant effect of genotype (p < 0.0001) on the transcript abundance of DLK1, PEG11, and MEG8 in the muscles of lambs with the callipyge allele. DLK1 and PEG11 transcript levels were elevated in the hypertrophied muscles of paternal heterozygous animals relative to animals of the other three genotypes. The PEG11 locus produces a single 6.5 kb transcript and two smaller antisense strand transcripts, referred to as PEG11AS, in skeletal muscle. PEG11AS transcripts were detectable over a 5.5 kb region beginning 1.2 kb upstream of the PEG11 start codon and spanning the entire open reading frame. Analysis of PEG11 expression by quantitative PCR shows a 200-fold induction in the hypertrophied muscles of paternal heterozygous animals and a 13-fold induction in homozygous callipyge animals. PEG11 transcripts were 14-fold more abundant than PEG11AS transcripts in the gluteus medius of paternal heterozygous animals. PEG11AS transcripts were expressed at higher levels than PEG11 transcripts in the gluteus medius of animals of the other three genotypes. CONCLUSIONS: The effect of the callipyge mutation has been to alter the expression of DLK1, GTL2, PEG11 and MEG8 in the hypertrophied skeletal muscles. Transcript abundance of DLK1 and PEG11 was highest in paternal heterozygous animals and exhibited polar overdominant gene expression patterns; therefore, both genes are candidates for causing skeletal muscle hypertrophy. There was unique relationship of PEG11 and PEG11AS transcript abundance in the paternal heterozygous animals that suggests a RNA interference mechanism may have a role in PEG11 gene regulation and polar overdominance in callipyge sheep.

Animals↗
PubMed2003

Search for the bovine homolog of the murine ped gene and characterization of its messenger RNA expression during bovine preimplantation development.

In mice, a gene (Ped: preimplantation embryo development) that regulates preimplantation embryonic growth, including cleavage rate and embryo survivability, has been described. The objective of the current study was to identify the bovine homolog of the Ped gene and to characterize the mRNA expression pattern of this gene during bovine preimplantation embryo development. The NCBI GenBank/EBI expressed sequence tags (EST) databases were searched for bovine ESTs that were homologous to the murine Ped gene, and the resulting ESTs were aligned and assembled into a contiguous sequence. The homology of the sequence to the murine Ped gene was confirmed. Primers were designed for the sequence, and the mRNA expression pattern was characterized during bovine preimplantation embryo development in vivo and in vitro. In vitro-produced bovine zygotes were cultured either in vitro, in synthetic oviduct fluid, or in vivo in the ewe oviduct for 1-7 days and processed for quantitative real-time polymerase chain reaction (PCR). Transcript abundance increased at each stage of development. However, the expression levels were consistently higher in in vivo-cultured embryos at all stages, with in vivo-cultured embryos showing a 9-fold increase in relative transcript abundance during culture from the zygote to the blastocyst stage in contrast to just under a 4-fold increase during the same culture period in vitro. The mRNA expression pattern of the gene was investigated in early- and late-cleaving two-cell embryos collected at 25, 28, 32, and >or=36 h postinsemination (pi). Transcript relative abundance was highest in those embryos that had cleaved by 28 hpi and decreased almost 3-fold thereafter. In conclusion, we have identified a potential bovine homolog of the murine Ped gene. We have characterized the mRNA expression pattern of this gene during preimplantation embryo development in cattle and shown that a greater relative abundance of the gene transcript is associated with embryos of higher quality (in vivo cultured) and greater developmental potential (early cleaving).

Amino Acid Sequence↗
PubMed2003

Differential involvement of the IDRS cis-element in the developmental and environmental regulation of the AtFer1 ferritin gene from Arabidopsis.

Four different ferritin genes have been identified in Arabidopsis thaliana, namely AtFer1, 2, 3 and 4. AtFer1, which strongly accumulates in leaves treated with excess iron, contains in its promoter an Iron- Dependent Regulatory Sequence (IDRS). The IDRS sequence is responsible for repression of AtFer1 transcription under conditions of low iron supply. Arabidopsis plants transformed with a 1,400-bp AtFer1 promoter, with either a wild-type or a mutated IDRS fused to the beta-glucuronidase (GUS) reporter gene, enabled us to analyze the activity of the AtFer1 promoter in different tissues as well as during age-dependent or dark-induced senescence. Our results show that IDRS mediates AtFer1 expression during dark-induced senescence while it does not affect AtFer1 expression during age-dependent senescence or in young seedlings. Photoinhibition promoted either by high light or chilling temperature, or wounding, does not activate the AtFer1 promoter. In contrast, AtFer2, AtFer3, AtFer4 transcript abundances are increased in response to photoinhibition and AtFer3 transcript abundance is increased upon wounding. Taken together, our results indicate that other cis-elements, different from the IDRS, regulate the territory-specific or developmental expression of AtFer1 gene. Expression of this gene appears insensitive to some of the environmental stresses tested, which instead up-regulate other members of the Arabidopsis ferritin gene family.

Arabidopsis↗
PubMed2007

Maturation medium supplements affect transcript level of apoptosis and cell survival related genes in bovine blastocysts produced in vitro.

The aim of the present study was to investigate whether protein or macromolecule supplements to in vitro maturation media affect transcript abundance of seven genes (Bax, Bcl2, Hsp70, IGF1, IGF1R, IGF2, and IGF2R) in oocytes and blastocysts. Cumulus-oocyte complexes aspirated from slaughterhouse ovaries were matured in TCM199 medium supplemented either with 10% FBS, 6% fatty acid free BSA (fafBSA) or 4% PVP40, then inseminated and cultured in vitro for 9 days. Transcript abundance analysis was carried out on immature and in vitro matured oocytes, as well as on blastocysts. Total RNA was isolated from pools of oocytes and embryos, reverse transcribed into cDNA and subjected to transcript analysis by real-time PCR. No transcript of IGF1 gene was detected either in oocytes or in blastocysts. Maturation conditions significantly affected transcript levels of investigated loci in blastocysts but not in matured oocytes, with one exception. Only relative abundance (RA) of IGF2 gene was higher in oocytes matured with fafBSA. Moreover, oocyte maturation with fafBSA elevated transcript abundance of IGF1R, IGF2, and IGF2R genes in resulting blastocysts, whereas Hsp70 transcription was stimulated by FBS supplementation. Thus, under described conditions, fafBSA may be the optimal supplement to IVM medium due to higher transcript level of growth factor coding genes accompanied by a lower transcript level of Hsp70.

Animals↗
PubMed1996

Identification of 4370 expressed sequence tags from a 3'-end-specific cDNA library of human skeletal muscle by DNA sequencing and filter hybridization.

A systematic study on the mRNA species expressed in the human skeletal muscle is presented in this paper. To carry on this study, a new method has been developed for the construction of unbiased cDNA libraries specially designed for the production of ESTs corresponding to the 3'-end portion of the mRNAs. The method has been applied to human skeletal muscle, where the analysis of the transcription profile is particularly difficult for the presence of several very abundant transcripts. To detect and quantify high-level mRNAs, the first 1054 ESTs were obtained from randomly selected clones. The 10 most abundant transcripts accounted for > 45% of the clones. Subsequently, these transcripts were identified by filter hybridization, thus making DNA sequencing more productive. Overall, 4370 clones were identified: 3372 by DNA sequencing and 998 by filter hybridization. The number of groups of sequences identifying individual transcripts was relatively low compared with other tissues, resulting in a total of 934 groups out of 4370 ESTs. Of these, 719 groups were represented by only one sequence.

Cloning, Molecular↗
PubMed2004

Differential gene expression profile of human tonsil high endothelial cells: implications for lymphocyte trafficking.

Lymphocyte recirculation is dependent on the interactions of adhesion and signaling molecules expressed on lymphocytes and their partners on high endothelial cells (HEC). Many of the events in this process have yet to be molecularly characterized. To identify novel HEC-specific proteins with potential function in the recruitment cascade, we sequenced a normalized human tonsil HEC cDNA library (generated from an inflamed tonsil) from which lymphocyte and human umbilical vein endothelial cell cDNAs had been subtracted. One-thousand forty-nine sequences were analyzed. All but three mapped to known cDNAs or genomic DNAs. The two most abundant transcripts encoded alpha2-macroglobulin and hevin. The next-abundant transcripts encoded several other protease inhibitors, making this protein class the most prominent in HEC. Several endothelial-specific transcripts were also identified, including those encoding E-selectin, vascular cell adhesion molecule-1, vascular endothelial-junctional adhesion molecule, and platelet-endothelial cell adhesion molecule-1. The library contains a great diversity of transcripts, and studies of the encoded proteins will provide further insight into the complex biology of these specialized endothelial cells.

Base Sequence↗
PubMed2004

Rapid transcriptome responses of maize (Zea mays) to UV-B in irradiated and shielded tissues.

BACKGROUND: Depletion of stratospheric ozone has raised terrestrial levels of ultraviolet-B radiation (UV-B), an environmental change linked to an increased risk of skin cancer and with potentially deleterious consequences for plants. To better understand the processes of UV-B acclimation that result in altered plant morphology and physiology, we investigated gene expression in different organs of maize at several UV-B fluence rates and exposure times. RESULTS: Microarray hybridization was used to assess UV-B responses in directly exposed maize organs and organs shielded by a plastic that absorbs UV-B. After 8 hours of high UV-B, the abundance of 347 transcripts was altered: 285 were increased significantly in at least one organ and 80 were downregulated. More transcript changes occurred in directly exposed than in shielded organs, and the levels of more transcripts were changed in adult compared to seedling tissues. The time course of transcript abundance changes indicated that the response kinetics to UV-B is very rapid, as some transcript levels were altered within 1 hour of exposure. CONCLUSIONS: Most of the UV-B regulated genes are organ-specific. Because shielded tissues, including roots, immature ears, and leaves, displayed altered transcriptome profiles after exposure of the plant to UV-B, some signal(s) must be transmitted from irradiated to shielded tissues. These results indicate that there are integrated responses to UV-B radiation above normal levels. As the same total UV-B irradiation dose applied at three intensities elicited different transcript profiles, the transcriptome changes exhibit threshold effects rather than a reciprocal dose-effect response. Transcriptome profiling highlights possible signaling pathways and molecules for future research.

Acclimatization↗
PubMed2000

Nicotinic acetylcholine receptor gene expression in developing chick autonomic ganglia.

The developmental expression patterns of ten genes encoding nicotinic acetylcholine receptor subunits were analyzed using Northern blots and in situ hybridization in chick peripheral ganglia of neural crest, placodal and dual embryonic origin. The superior cervical and ciliary ganglia were investigated in detail because they accumulated relatively abundant transcripts of the alpha3, beta4, alpha5 and alpha7 genes. In the superior cervical ganglion, these four mRNA species had similar developmental time-courses. They appeared at embryonic day 8 (E8), increased steadily until E16 and maintained a rather high plateau level until E18. In the ciliary ganglion, alpha7 transcripts were already abundant at E6, increased until E10, and considerably decreased thereafter. High-resolution in situ hybridization showed that alpha7 transcripts were present in all cell types of the E6 ciliary ganglion, whereas they were restricted to large neuronal somas at E16. Transfections with a reporter gene under the control of the alpha7 promoter demonstrated that a sharp developmental divide occurred at E11-12, after which stage the promoter was activatable in neurons exclusively.

Animals↗
PubMed2004

Putative protease inhibitor gene discovery and transcript profiling during fruit development and leaf damage in grapefruit (Citrus paradisi Macf.).

Seven putative protease inhibitor (PPI) cDNAs, representing four protein families, were isolated from a grapefruit (Citrus paradisi Macf. Cv. Marsh) immature fruit flavedo cDNA library. Cloned open reading frames encoded proteins with similarity to, and protein signatures for: legume Kuntiz inhibitors (lkiL-1, lkiL-2, lkiL-3), potato trypsin inhibitor I (ptiIL-1), serpins (serpL-1), cystatins (cystL-1), and gamma thionins (gthL-1). Response of transcript abundance to fruit development and leaf wounding was determined for all but lkiL-1 using real-time RT-PCR. Immature leaves had the highest transcript levels for all PPIs. The gthL-1 transcript in immature leaves was the most abundant transcript but was absent from healthy mature leaves. In fruit flavedo, transcripts for all PPIs were most abundant in youngest fruit (<15 mm dia. fruit), and declined during development, but displayed different patterns of developmental change. Mechanical or Diaprepes root weevil (DRW) feeding damage to leaves caused a <10-fold reduction or had no effect on transcript level with the exception of gthL-1 which, as a result of damage, increased >50-fold in mature leaves and decreased >1400-fold in immature leaves. This developmental control of transcript response to wounding in a woody perennial is opposite of what has been observed for defensive proteinase inhibitors (PIs) in other plants (typically herbaceous and/or annual plants), where younger leaves typically invoke a higher defensive proteinase inhibitor transcript accumulation than older tissues. Except for gthL-1, the PPI transcripts were minimally responsive or unresponsive to wounding. Changes in PPI transcript levels suggest diverse roles for the products of these genes in citrus, with only gthL-1 responding in a defense-like manner.

Citrus↗
PubMed2006

Candidate genes affecting Drosophila life span identified by integrating microarray gene expression analysis and QTL mapping.

The current increase in life expectancy observed in industrialized societies underscores the need to achieve a better understanding of the aging process that could help the development of effective strategies to achieve healthy aging. This will require not only identifying genes involved in the aging process, but also understanding how their effects are modulated by environmental factors, such as dietary intake and life style. Although the human genome has been sequenced, it may be impractical to study humans or other long-lived organisms to gain a mechanistic understanding about the aging process. Thus, short-lived animal models are essential to identifying the mechanisms and genes that affect the rate and quality of aging as a first step towards identifying genetic variants in humans. In this study, we investigated gene expression changes between two strains of Drosophila (Oregon and 2b) for which quantitative trait loci (QTLs) affecting life span were identified previously. We collected males and females from both strains at young and old ages, and assessed whole genome variation in transcript abundance using Affymetrix GeneChips. We observed 8217 probe sets with detectable transcripts. A total of 2371 probe sets, representing 2220 genes, exhibited significant changes in transcript abundance with age; and 839 probe sets were differentially expressed between Oregon and 2b. We focused on the 359 probe sets (representing 354 genes) that exhibited significant changes in gene expression both with age and between strains. We used these genes to integrate the analysis of microarray gene expression data, bioinformatics, and the results of genetic mapping studies reported previously, to identify 49 candidate genes and four pathways that could potentially be responsible for regulating life span and involved in the process of aging in Drosophila and humans.

Aging↗
PubMed2005

Identification and analysis of teleost slow muscle troponin T (sTnT) and intronless TnT genes.

In the present study cDNA clones representing two slow skeletal muscle troponin T genes (sTnT1sb and sTnT2sb) in the sea bream (Sparus auratus), an important aquaculture species, were isolated and characterised. A third, intronless, TnT gene (iTnTsb), which is an apparent orthologue of a previously described zebrafish TnT, was also isolated. In adult sea bream sTnT expression was restricted to red muscle and, using northern blotting, a single low abundance transcript was identified for sTnT1sb (1260 nucleotides) and a single high abundance transcript was identified for sTnT2sb (1000 nucleotides). In contrast, iTnTsb is predominantly expressed in adult fast muscle. All three TnT genes are also expressed during larval development. Phylogenetic analysis of sea bream sTnT proteins to identify maximum parsimony showed that iTnTsb, sTnT1sb and sTnT2sb each cluster in independent groups. sTnT1sb clustered with other vertebrate sTnTs, while sTnT2 clustered with a group of fish specific sequences (from Fugu rubripes, Oryzia latipes and Salmo trutta). The teleost sTnT2 and iTnT each constitute new, apparently teleost specific, TnT groups. Analysis of the corresponding Fugu scaffold indicates that sTnT2sb is encoded by a gene with twelve exons. The two sTnT cDNAs isolated in sea bream probably arose by duplication of an ancestral gene, and iTnT by reverse transcription. It remains to be established if the encoded proteins have different structural and mechanistic roles in fish muscle.

Amino Acid Sequence↗
PubMed2004

Serial Analysis of Gene Expression: Applications in Malaria Parasite, Yeast, Plant, and Animal Studies.

The serial analysis of gene expression (SAGE) method is based on the isolation of unique sequence tags from individual transcripts and concatenation of tags serially into long DNA molecules. SAGE is an innovative technique that offers the potential of cataloging both the identity and relative frequencies of mRNA transcripts in a given RNA preparation. It can quantify low-abundance transcripts and reliably detect relatively small differences in transcript abundance between cell populations. SAGE data can be used to complement studies in cases where other gene expression methods may be more convenient or efficient. SAGE can be used in a wide variety of applications to identify disease-related genes, to analyze the effect of drugs on tissues, and to provide insights into the disease pathways. The most important application of SAGE is the identification of differentially expressed genes. In this review, we describe various applications of this powerful technology in malarial parasite, yeast, plant, and animal systems.

Journal Article↗
PubMed1995

Cell stress and translational inhibitors transiently increase the abundance of mammalian SINE transcripts.

The abundance of Alu RNA is transiently increased by heat shock in human cell lines. This effect is specific to Alu repeats among Pol III transcribed genes, since the abundance of 7SL, 7SK, 5S and U6 RNAs is essentially unaffected by heat shock. The rapid induction of Alu expression precedes the heat shock induction of mRNAs for the ubiquitin and HSP 70 heat shock genes. Heat shock mimetics also transiently induce Alu expression indicating that increased Alu expression is a general cell-stress response. Cycloheximide treatment rapidly and transiently increases the abundance of Alu RNA. Again, compared with other genes transcribed by Pol III, this increase is specific to Alu. However, as distinguished from the cell stress response, cycloheximide does not induce expression of HSP 70 and ubiquitin mRNAs. Puromycin also increases Alu expression, suggesting that this response is generally caused by translational inhibition. The response of mammalian SINEs to cell stress and translational inhibition is not limited to SINEs which are Alu homologues. Heat shock and cycloheximide each transiently induce Pol III directed expression of B1 and B2 RNAs in mouse cells and C-element RNA in rabbit cells. Together, these three species exemplify the known SINE composition of placental mammals, suggesting that mammalian SINEs are similarly regulated and may serve a common function.

3T3 Cells↗
PubMed1999

Ca2+-ATPases and their expression in the mammary gland of pregnant and lactating rats.

The transcellular Ca2+ fluxes required for milk production must be rigorously regulated to maintain the low cytosolic Ca2+ concentrations critical to cell function. Ca2+-ATPases play a critical role in the maintenance of this cellular Ca2+ homeostasis. Using RT-PCR and sequencing, we identified six Ca2+ pumps in lactating mammary tissue. Three plasma membrane Ca2+-ATPases (PMCAs) were found (PMCA1b, PMCA2b, and PMCA4b). Two sarco (endo)plasmic reticulum Ca2+-ATPases (SERCAs) were identified (SERCA2 and SERCA3), and the rat homologue to the yeast Golgi Ca2+-ATPase RS-10 was also found. The pattern of mRNA expression of each of these pumps was examined in rat mammary tissue from the 7th day of pregnancy to the 21st day of lactation. Northern blots revealed increased mRNA expression for all Ca2+ pumps by the 14th day of lactation, and transcripts continued to increase through the 18th day of lactation. PMCA1b, PMCA4b, SERCA2, and SERCA3 showed the lowest levels of expression. RS-10 transcripts were more abundant than SERCA2, SERCA3, PMCA1b, and PMCA4b. RS-10 was the only pump to increase in expression before parturition. PMCA2b was the most abundant transcript found in lactating mammary tissue. At peak lactation, expression of PMCA2b approached that of actin. The high expression, high affinity for Ca2+, and high activity at low calmodulin concentrations exhibited by PMCA2b suggest that it is uniquely suited for maintenance of Ca2+ homeostasis in the lactating mammary gland. The pattern of expression and abundance of RS-10 suggest that it is a candidate for the Golgi Ca2+-ATPase shown to be important in maintaining the Golgi Ca2+ concentration required for casein synthesis and micelle formation.

Animals↗