A testis-expressed Zn finger gene (ZNF76) in human 6p21.3 centromeric to the MHC is closely linked to the human homolog of the t-complex gene tcp-11

march5 Governs the Convergence and Extension Movement for Organization of the Telencephalon and Diencephalon in Zebrafish Embryos

MARCH5 is a RING finger E3 ligase involved in mitochondrial integrity, cellular protein homeostasis, and the regulation of mitochondrial fusion and fission. To determine the function of MARCH5 during development, we assessed transcript expression in zebrafish embryos. We found that march5 transcripts were of maternal origin and evenly distributed at the 1-cell stage, except for the mid-blastula transition, with expression predominantly in the developing central nervous system at later stages of embryogenesis. Overexpression of march5 impaired convergent extension movement during gastrulation, resulting in reduced patterning along the dorsoventral axis and alterations in the ventral cell types. Overexpression and knockdown of march5 disrupted the organization of the developing telencephalon and diencephalon. Lastly, we found that the transcription of march5 was tightly regulated by the transcriptional regulators CHOP, C/EBPα, Staf, Znf143a, and Znf76. These results demonstrate the essential role of March5 in the development of zebrafish embryos.

A small-molecule inhibitor of PIM kinases as a potential treatment for urothelial carcinomas

The proto-oncogene proviral integration site for moloney murine leukemia virus (PIM) kinases (PIM-1, PIM-2, and PIM-3) are serine/threonine kinases that are involved in a number of signaling pathways important to cancer cells. PIM kinases act in downstream effector functions as inhibitors of apoptosis and as positive regulators of G₁-S phase progression through the cell cycle. PIM kinases are upregulated in multiple cancer indications, including lymphoma, leukemia, multiple myeloma, and prostate, gastric, and head and neck cancers. Overexpression of one or more PIM family members in patient tumors frequently correlates with poor prognosis. The aim of this investigation was to evaluate PIM expression in low- and high-grade urothelial carcinoma and to assess the role PIM function in disease progression and their potential to serve as molecular targets for therapy. One hundred thirty-seven cases of urothelial carcinoma were included in this study of surgical biopsy and resection specimens. High levels of expression of all three PIM family members were observed in both noninvasive and invasive urothelial carcinomas. The second-generation PIM inhibitor, TP-3654, displays submicromolar activity in pharmacodynamic biomarker modulation, cell proliferation studies, and colony formation assays using the UM-UC-3 bladder cancer cell line. TP-3654 displays favorable human ether-à-go-go-related gene and cytochrome P450 inhibition profiles compared with the first-generation PIM inhibitor, SGI-1776, and exhibits oral bioavailability. In vivo xenograft studies using a bladder cancer cell line show that PIM kinase inhibition can reduce tumor growth, suggesting that PIM kinase inhibitors may be active in human urothelial carcinomas.

The PIM kinases in hematological cancers

The PIM genes represent a family of proto-oncogenes that encode three different serine/threonine protein kinases (PIM1, PIM2 and PIM3) with essential roles in the regulation of signal transduction cascades, which promote cell survival, proliferation and drug resistance. PIM kinases are overexpressed in several hematopoietic tumors and support in vitro and in vivo malignant cell growth and survival, through cell cycle regulation and inhibition of apoptosis. PIM kinases do not have an identified regulatory domain, which means that these proteins are constitutively active once transcribed. They appear to be critical downstream effectors of important oncoproteins and, when overexpressed, can mediate drug resistance to available agents, such as rapamycin. Recent crystallography studies reveal that, unlike other kinases, they possess a hinge region, which creates a unique binding pocket for ATP, offering a target for an increasing number of potent small-molecule PIM kinase inhibitors. Preclinical studies in models of various hematologic cancers indicate that these novel agents show promising activity and some of them are currently being evaluated in a clinical setting. In this review, we profile the PIM kinases as targets for therapeutics in hematologic malignancies.

Transcription of the human cell cycle regulated BUB1B gene requires hStaf/ZNF143

BubR1 is a key protein mediating spindle checkpoint activation. Loss of this checkpoint control results in chromosomal instability and aneuploidy. The transcriptional regulation of the cell cycle regulated human BUB1B gene, which encodes BubR1, was investigated in this report. A minimal BUB1B gene promoter containing 464 bp upstream from the translation initiation codon was sufficient for cell cycle regulated promoter activity. A pivotal role for transcription factor hStaf/ZNF143 in the expression of the BUB1B gene was demonstrated through gel retardation assays, transient expression of mutant BUB1B promoter–reporter gene constructs and chromatin immunoprecipitation assay. Two phylogenetically conserved hStaf/ZNF143-binding sites (SBS) were identified which are indispensable for BUB1B promoter activity. In addition, we found that the domain covering the transcription start sites contains conserved boxes homologous to initiator (Inr), cell cycle dependent (CDE) and cell cycle genes homology regions (CHR) elements. Mutations within the CDE and CHR elements led to diminished cell cycle regulation of BUB1B transcription. These results demonstrate that BUB1B gene transcription is positively regulated by hStaf/ZNF143, a ubiquitously expressed factor, and that the CDE-CHR tandem element was essential for G2/M-specific transcription of the BUB1B gene.

A Genome Scale Location Analysis of Human Staf/ZNF143-binding Sites Suggests a Widespread Role for Human Staf/ZNF143 in Mammalian Promoters

Staf was originally identified as the transcriptional activator of Xenopus tRNA(Sec) and small nuclear (sn) RNA-type genes. Recently, transcription of seven human (h) protein coding genes was reported to be activated by the human ortholog hStaf/ZNF143. Here we have used a combined in silico and biochemical approach to identify 1175 conserved hStaf/ZNF143-binding sites (SBS) distributed in 938 promoters of four mammalian genomes. The SBS shows a significant positional preference and occurs mostly within 200 bp upstream of the transcription start site. Chromatin immunoprecipitation assays with 295 of the promoters established that 90% contain bona fide SBS. By extrapolating the values of this mapping to the full sizes of the mammalian genomes, we can infer the existence of at least 2500 SBS distributed in 2000 promoters. This unexpected large number strongly suggests that SBS constitutes one of the most widespread transcription factor-binding sites in mammalian promoters. Furthermore, we demonstrated that the presence of the SBS alone is sufficient to direct expression of a luciferase reporter gene, suggesting that hStaf/ZNF143 can recruit per se the transcription machinery.

ZNF143 mediates basal and tissue-specific expression of human transaldolase

Transaldolase regulates redox-dependent apoptosis through controlling NADPH and ribose 5-phosphate production via the pentose phosphate pathway. The minimal promoter sufficient to drive chloramphenicol acetyltransferase reporter gene activity was mapped to nucleotides -49 to -1 relative to the transcription start site of the human transaldolase gene. DNase I footprinting with nuclear extracts of transaldolase-expressing cell lines unveiled protection of nucleotides -29 to -16. Electrophoretic mobility shift assays identified a single dominant DNA-protein complex that was abolished by consensus sequence for transcription factor ZNF143/76 or mutation of the ZNF76/143 motif within the transaldolase promoter. Mutation of an AP-2alpha recognition sequence, partially overlapping the ZNF143 motif, increased TAL-H promoter activity in HeLa cells, without significant impact on HepG2 cells, which do not express AP-2alpha. Cooperativity of ZNF143 with AP-2alpha was supported by supershift analysis of HeLa cells where AP-2 may act as cell type-specific repressor of TAL promoter activity. However, overexpression of full-length ZNF143, ZNF76, or dominant-negative DNA-binding domain of ZNF143 enhanced, maintained, or abolished transaldolase promoter activity, respectively, in HepG2 and HeLa cells, suggesting that ZNF143 initiates transcription from the transaldolase core promoter. ZNF143 overexpression also increased transaldolase enzyme activity. ZNF143 and transaldolase expression correlated in 21 different human tissues and were coordinately upregulated 14- and 34-fold, respectively, in lactating mammary glands compared with nonlactating ones. Chromatin immunoprecipitation studies confirm that ZNF143/73 associates with the transaldolase promoter in vivo. Thus, ZNF143 plays a key role in basal and tissue-specific expression of transaldolase and regulation of the metabolic network controlling cell survival and differentiation.

Human synaptobrevin-like 1 gene basal transcription is regulated through the interaction of selenocysteine tRNA gene transcription activating factor-zinc finger 143 factors with evolutionary conserved cis-elements

The synaptobrevin-like 1 (SYBL1) gene is ubiquitously expressed and codes for an unusual member of the v-SNAREs molecules implicated in cellular exocytosis. This X-linked gene has the peculiarity of also being present on the Y chromosome in a transcriptional inactive status. Moreover, although ubiquitous, the function of SYBL1 is prominent in specific tissues, such as brain. As a first insight into the molecular mechanisms controlling SYBL1 expression, in this report we describe the extent and role of SYBL1 upstream regions and characterize the binding of trans-acting factors. In vivo foot-printing experiments identify three protected regions. Band shift and transient reporter gene assays indicate a strong role of two of these evolutionary conserved regions in regulating SYBL1 transcription. Because one site is the classical CAAT box, we characterized the binding to the other site of the mammalian homologues of the selenocysteine tRNA gene transcription activating factor (Staf) family, zinc-finger transcription factors, and their role in regulating SYBL1 expression. The results reported here clarify that a Staf-zinc finger family factor, together with the CAAT factor, is the major nuclear protein bound to the SYBL1 promoter region and is responsible for its regulation in HeLa cells, thus identifying the basic control of SYBL1 transcription. In vivo binding of Staf proteins to the SYBL1 promoter is confirmed by chromatin immunoprecipitation assays. Our results identify a fourth mRNA promoter stimulated by a member of the Staf-zinc finger family, the function of which on mRNA polymerase II promoters is still very poorly understood.

Complex regulation of human neuronal nitric-oxide synthase exon 1c gene transcription. Essential role of Sp and ZNF family members of transcription factors

Neuronal nitric-oxide synthase (nNOS) is expressed in a variety of human tissues and shows a complex transcriptional regulation with the presence of nine alternative first exons (1a-1i) resulting in nNOS transcripts with differing 5'-untranslated regions. We previously demonstrated that nNOS exon 1c, one of the predominant transcripts in the human gastrointestinal tract, is driven by a separate promoter (Saur, D., Paehge, H., Schusdziarra, V., and Allescher, H. D. (2000) Gastroenterology 118, 849-858). The present study focused on the quantitative expression of nNOS first exon variants in different human tissues and the characterization of the basal nNOS exon 1c promoter. In human brain, skeletal muscle, colon, and TGW-nu-I neuroblastoma cells, first exon expression patterns were analyzed by quantitative real-time reverse transcription-PCR. In these tissues/cells exon 1c was one of the most abundant first exons of nNOS. By transient transfections of TGW-nu-I and HeLa cells with reporter plasmids containing a series of 5' and 3' deletions in the exon 1c regulatory region, the minimal TATA-less promoter was localized within 44 base pairs. Gel mobility shift assays of this cis-regulatory region revealed a high complexity of the basal promoter with a cooperative binding of several transcription factors, like Sp and ZNF family members. When the Sp binding site of the minimal promoter construct was mutated, promoter activity was completely abolished in both cell lines, whereas mutation of the common binding site of ZNF76 and ZNF143 resulted in a decrease of 53% in TGW-nu-I and 37% in HeLa cells. In Drosophila Schneider cells expression of Sp1, the long Sp3 isoform, ZNF76 and ZNF143 potently transactivated the nNOS exon 1c promoter. These results identify the critical regulatory region for the nNOS exon 1c basal promoter and stress the functional importance of multiple protein complexes involving Sp and ZNF families of transcription factors in regulating nNOS exon 1c transcription.

Fertilization promoting peptide — A possible regulator of sperm function in vivo

Fertilization promoting peptide (FPP), a tripeptide related to thyrotrophin releasing hormone (TRH), is found in seminal plasma. Recent evidence obtained in vitro suggests that FPP may play an important role in regulating sperm fertility in vivo. Specifically, FPP initially stimulates nonfertilizing (uncapacitated) spermatozoa to "switch on" and become fertile more quickly, but then arrests capacitation so that spermatozoa do not undergo spontaneous acrosome loss and therefore do not lose fertilizing potential. These responses are mimicked, and indeed augmented, by adenosine, known to regulate the adenylyl cyclase (AC)/cAMP signal transduction pathway. Both FPP and adenosine have been shown to stimulate cAMP production in uncapacitated cells but inhibit it in capacitated cells, with FPP receptors somehow interacting with adenosine receptors and G proteins to achieve regulation of AC. These events affect the tyrosine phosphorylation state of various proteins, some being important in the initial "switching on," others possibly being involved in the acrosome reaction itself. Calcitonin and angiotensin II, also found in seminal plasma, have similar effects in vitro on uncapacitated spermatozoa and can augment responses to FPP, suggesting that all four molecules may be involved in regulating availability of cAMP. It is plausible that these molecules have similar effects in vivo, affecting fertility by stimulating and then maintaining fertilizing potential. Either reductions in the availability of FPP, adenosine, calcitonin, and angiotensin II or defects in their receptors could contribute to male infertility. These exciting results may provide new approaches for diagnostic tests and treatments of certain categories of male infertility.

Transcriptional regulation of the mouse cytosolic chaperonin subunit gene Ccta/t-complex polypeptide 1 by selenocysteine tRNA gene transcription activating factor family zinc finger proteins

The chaperonin containing t-complex polypeptide 1 (CCT) is a molecular chaperone assisting in the folding of proteins in eukaryotic cytosol, and the Ccta (encoding the alpha subunit of CCT)/t-complex polypeptide 1 gene encodes the alpha subunit of CCT. We show here that transcription of the mouse Ccta gene is regulated by selenocysteine tRNA gene transcription activating factor (Staf) family zinc-finger transcription factors ZNF143 and ZNF76. Reporter gene assay using HeLa cells indicated that the Ccta gene promoter contains two 18-base pair-long cis-acting elements with similar sequences at -70 and -20 base pairs (designated CCT alpha subunit gene transcription activating element 1 (CAE1) and CAE2, respectively). By yeast one-hybrid screening of CAE1-binding factors, we isolated human ZNF143, which is known to activate transcription of selenocysteine tRNA and small nuclear RNA genes. DNA binding domains of ZNF143 and ZNF76 produced in E. coli recognized CAE1 and CAE2 elements in electrophoretic mobility shift assay. HeLa cell nuclear extract contained a protein that specifically binds to CAE1 and CAE2 and recognized by anti-ZNF143 antibody. Transcription from a minimal Ccta promoter containing CAE2 element in HeLa cells was enhanced by overexpression of full-length ZNF143 and ZNF76 but inhibited by that of their DNA binding domains alone. These results demonstrate that the Staf family proteins control transcription of at least one of the chaperone-encoding genes besides that of tRNA and small nuclear RNA genes. These RNA and chaperone genes are suggested to be coregulated to facilitate synthesis of mature proteins during active cell growth.

Large-scale chromatin organization of the major histocompatibility complex and other regions of human chromosome 6 and its response to interferon in interphase nuclei

The large-scale chromatin organization of the major histocompatibility complex and other regions of chromosome 6 was studied by three-dimensional image analysis in human cell types with major differences in transcriptional activity. Entire gene clusters were visualized by fluorescence in situ hybridization with multiple locus-specific probes. Individual genomic regions showed distinct configurations in relation to the chromosome 6 terrritory. Large chromatin loops containing several megabases of DNA were observed extending outwards from the surface of the domain defined by the specific chromosome 6 paint. The frequency with which a genomic region was observed on an external chromatin loop was cell type dependent and appeared to be related to the number of active genes in that region. Transcriptional up-regulation of genes in the major histocompatibility complex by interferon-gamma led to an increase in the frequency with which this large gene cluster was found on an external chromatin loop. Our data are consistent with an association between large-scale chromatin organization of specific genomic regions and their transcriptional status.

Construction of a high-resolution 2.5-Mb transcript map of the human 6p21.2-6p21.3 region immediately centromeric of the major histocompatibility complex

We have constructed a 2.5-Mb physical and transcription map that spans the human 6p21.2-6p21.3 region and includes the centromeric end of the MHC, using a combination of techniques. In total 88 transcription units including exons, cDNAs, and cDNA contigs were characterized and 60 were confidently positioned on the physical map. These include a number of genes encoding nuclear and splicing factors (Ndr kinase, HSU09564, HSRP20); cell cycle, DNA packaging, and apoptosis related [p21, HMGI(Y), BAK]; immune response (CSBP, SAPK4); transcription activators and zinc finger-containing genes (TEF-5, ZNF76); embryogenesis related (Csa-19); cell signaling (DIPP); structural (HSET), and other genes (TULP1, HSPRARD, DEF-6, EO6811, cyclophilin), as well as a number of RP genes and pseudogenes (RPS10, RPS12-like, RPL12-like, RPL35-like). Furthermore, several novel genes (a Br140-like, a G2S-like, a FBN2-like, a ZNF-like, and B1/KIAA0229) have been identified, as well as cDNAs and cDNA contigs. The detailed map of the gene content of this chromosomal segment provides a number of candidate genes, which may be involved in several biological processes that have been associated with this region, such as spermatogenesis, development, embryogenesis, and neoplasia. The data provide useful tools for synteny studies between mice and humans, for genome structure analysis, gene density comparisons, and studies of nucleotide composition, of different isochores and Giemsa light and Giemsa dark bands.

Evidence for major histocompatibility complex-mediated effects on spermatogenesis in humans

Studies in fertile and infertile populations suggest an influence of genes of the major histocompatibility complex (MHC) on reproduction, although it remains unresolved if MHC-mediated effects on fertility are based on direct immunological or non-immunological effects of human leukocyte antigen (HLA) genes or rather on defects in MHC-associated non-HLA genes which affect gamete quality and embryonic development. We analysed allele frequencies for HLA class II loci DQA1, DQB1 and DRB1 and HLA class II haplotype frequencies in couples with tubal and andrological infertility who were treated with assisted reproductive techniques. Males with severe andrological infertility had significantly different allele frequencies for all three HLA loci when compared to males with normozoospermia, whereas no difference was found in the females. Differences in allele frequencies were stronger when only males whose partners achieved pregnancies after assisted reproduction treatment were compared. In those subgroups, we could also observe significant differences in three locus HLA class II haplotype frequencies. In summary, patients with male factor infertility differ in their HLA class II allele constitution from males with normozoospermia, which suggests that genes identical to or located in close vicinity to HLA class II genes may influence spermatogenesis and male gamete function.

AATF, a novel transcription factor that interacts with Dlk/ZIP kinase and interferes with apoptosis

Dlk, also known as ZIP kinase, is a serine/threonine kinase that is tightly associated with nuclear structures. Under certain conditions, which require cytoplasmic localization, Dlk can induce apoptosis. In search for interaction partners that might serve as regulators or targets of this kinase we identified apoptosis antagonizing transcription factor (AATF), a nuclear phosphoprotein of 523 amino acids. The 1.8 kb mRNA seems to be ubiquitously expressed. AATF contains an extremely acidic domain and a putative leucine zipper characteristic of transcription factors. Indeed, a Gal4-BD-AATF fusion protein exhibited strong transactivation activity. Interestingly, AATF interfered with Dlk-induced apoptosis.

New insights into the t-complex and control of sperm function

The mouse t-complex, located on chromosome 17, contains genes known to influence male, but not female, fertility. Although some t-complex genes are recessive lethals, t-chromosomes are maintained in the population by transmission ratio distortion. When male mice heterozygous for the t-chromosome mate with wild-type females, most offspring will possess the t-chromosome, indicating a link between t-complex genes and sperm function. Several proteins coded for by t-complex genes have been localised in the sperm flagellum, suggesting roles relating to motility. Another t-complex protein appears able to regulate the adenylyl cyclase/cAMP signal transduction pathway, known to play an important role in capacitation. Defective motility and/or failure to capacitate ("switch on") would result in poorly fertile or infertile spermatozoa. Given the existence of human homologues for many genes in the t-complex and the prevalence of "male factor" infertility, information obtained about the t-complex not only will provide insight into basic biological mechanisms but may be of future clinical relevance as well.

ZNF76 and ZNF143 are two human homologs of the transcriptional activator Staf

The transcriptional activator Staf, originally identified in Xenopus laevis, is implicated in the enhanced transcription of small nuclear RNA (snRNA) and snRNA-type genes by RNA polymerases II (Pol II) and III (Pol III). This zinc finger protein also possesses the capacity to stimulate expression from a Pol II mRNA promoter. Here, we report a study on two human proteins, ZNF76 and ZNF143, that are 64 and 84% identical to their Xenopus counterpart, respectively. Northern blot analysis revealed that ZNF76 and ZNF143 mRNAs were expressed in all normal adult tissues examined. By using in vivo and in vitro assays, we have analyzed the DNA binding capacities and transcriptional properties of ZNF76 and ZNF143. The binding affinities of ZNF76 and ZNF143 for Staf divergent responsive elements were determined by gel shift assays, which revealed that the two proteins bound a same DNA motif with similar affinities. Also, polypeptide sequences containing the seven zinc fingers of ZNF76 and ZNF143 could efficiently repress in vivo the activated transcription from an snRNA-type promoter. Transfection experiments in Drosophila cells showed that ZNF76 and ZNF143 can activate transcription from an mRNA promoter through the Staf binding site. Finally, chimeric ZNF76 and ZNF143 proteins, carrying a heterologous DNA binding domain, are able to activate a Pol II mRNA promoter and snRNA Pol II and Pol III promoters in Xenopus oocytes, through the heterologous DNA binding site. Taken together, these findings demonstrate that ZNF76 and ZNF143 are two members of a same family of transactivator proteins. ZNF143 constitutes the human ortholog of the Xenopus Staf, and ZNF76 is a novel DNA binding protein related to Staf and ZNF143.

Modulation of mammalian sperm function by fertilization promoting peptide (FPP)

Fertilization promoting peptide (FPP; pGlu-Glu-ProNH2) is produced by the prostate gland and secreted into seminal plasma. When added to uncapacitated mouse and human sperm suspensions, it stimulates capacitation as demonstrated by both cytological changes and increased fertilizing ability in vitro. When added to capacitated suspensions, FPP inhibits spontaneous acrosome loss but cells retain high fertility in vitro. Adenosine elicits similar responses to FPP in both uncapacitated and capacitated cells and FPP + adenosine has a greater effect on uncapacitated cells than either used individually. We have proposed that these two molecules modulate the same pathway (adenylate cyclase/cAMP) but act via different receptors. The structure of FPP is crucial for bioactivity: loss of the terminal amide group abolishes activity and substitution of the central glutamic acid can markedly alter activity. Most recently we have found that stimulation of TCP-11, the product of the mouse t-complex gene Tcp-11, elicits responses indistinguishable from those obtained with FPP and we have hypothesized that the protein TCP-11 is the receptor for FPP. The existence of a human homologue for Tcp-11 suggests that the gene product, in conjunction with FPP, could play an important role in human fertility.

Physical map of human 6p21.2-6p21.3: region flanking the centromeric end of the major histocompatibility complex

We have physically mapped and cloned a 2.5-Mb chromosomal segment flanking the centromeric end of the major histocompatibility complex (MHC). We characterized in detail 27 YACs, 144 cosmids, 51 PACs, and 5 BACs, which will facilitate the complete genomic sequencing of this region of chromosome 6. The contig contains the genes encoding CSBP, p21, HSU09564 serine kinase, ZNF76, TCP-11, RPS10, HMGI(Y), BAK, and the human homolog of Tctex-7 (HSET). The GLO1 gene was mapped further centromeric in the 6p21.2-6p21.1 region toward TCTE-1. The gene order of the GLO1-HMGI(Y) segment in respect to the centromere is similar to the gene order in the mouse t-chromosome distal inversion, indicating that there is conservation in gene content but not gene order between humans and mice in this region. The close linkage of the BAK and CSBP genes to the MHC is of interest because of their possible involvement in autoimmune disease.

Two distinct domains in Staf to selectively activate small nuclear RNA-type and mRNA promoters

Staf is a transcriptional activator of prime importance for enhanced transcription of small nuclear (snRNA) and snRNA-type genes transcribed by RNA polymerases II and III (Pol II and III). In addition to this activity, it also possesses the capacity to stimulate expression from an RNA polymerase II mRNA promoter. This promiscuous activator thus provides a useful model system for studying the mechanism by which one single transcription factor can activate a large variety of promoters. Here, we report the use of in vivo assays to identify the Staf activation domains involved in promoter selectivity. Analysis of Staf mutants reveals the existence of two physically and functionally distinct regions, outside of the DNA binding domain, responsible for mediating selective transcriptional activation. While a 93-amino-acid domain, with the striking presence of four repeated units, is specialized for transcriptional activation of an mRNA promoter, a segment of only 18 amino acids, with a critical Leu-213 residue, acts specifically on Pol II and Pol III snRNA and snRNA-type promoters. In addition, this study disclosed the fundamental importance of invariant leucine and aspartic acid residues located in each repeat unit of the mRNA activation domain. Staf is therefore the first transcriptional activator described so far to harbor two physically and functionally distinct activator domains. This finding suggests that the same activator can contact different, specialized transcription complexes formed on different types of basal promoters through promoter-specific transactivation pathways.

Molecular cloning and characterization of the murine staf cDNA encoding a transcription activating factor for the selenocysteine tRNA gene in mouse mammary gland

We have isolated and characterized a cDNA encoding a transcription activating factor for the mouse selenocysteine tRNA (tRNAsec) gene from mouse mammary gland. The full-length cDNA, designated m-Staf, has a 1878-base pair open reading frame encoding 626 amino acids. The predicted amino acid sequence of m-Staf is highly homologous to that of Staf, another selenocysteine tRNA gene transcription activating factor of Xenopus laevis. Like Staf, m-Staf contains seven tandemly repeated zinc fingers and four repeated motifs. Gel shift assays indicated that the recombinant m-Staf specifically bound to the activator element region in the mouse tRNAsec gene. Transient co-transfection experiments in Drosophila Schneider cells, which lack endogenous Staf-like binding activity, showed that m-Staf increased the mouse tRNAsec gene transcription about 15-fold, whereas it stimulated Pol II-dependent thymidine kinase promoter only 2-fold. Northern blot analysis detected the presence of a 3.4-kilobase pair m-Staf transcript, which was widely but differentially expressed in various murine tissues. The binding activity of m-Staf in mouse mammary gland was undetectable during virgin and postlactating periods but increased markedly in parallel with the increase of tRNAsec transcript during the periods of pregnancy and lactation, when the gland undergoes growth and development. These results indicate that m-Staf is a transcriptional activator of the mouse tRNAsec gene and that its binding activity in the mammary gland undergoes developmental alterations.

A fertilization promoting peptide (FPP)-related tripeptide competitively inhibits responses to FPP: a cause of male subfertility?

Fertilization promoting peptide (FPP; pGlu-Glu-ProNH2), a tripeptide structurally related to thyrotrophin releasing hormone (TRH; pGlu-His-ProNH2), is present in the prostate gland and seminal plasma of several mammalian species. FPP has been shown not only to stimulate the capacitation and fertilizing ability of epididymal mouse and ejaculated human spermatozoa, but also to inhibit spontaneous acrosome loss in mouse spermatozoa. These results suggest a possible role in vivo for FPP to maximize the fertilizing potential of the few cells that reach the ampulla. In this study we have investigated the effects of FPP-related peptides on mouse sperm capacitation and the acrosome reaction (using chlortetracycline fluorescence) and in vitro fertilizing ability. Deamidated FPP neither stimulated capacitation when tested at 50-200 nM nor interfered with FPP's stimulation of capacitation. Three neutral peptides (pGlu-Phe-ProNH2, MeO-FPP, pGlu-Gln-ProNH2) were also evaluated. pGlu-Phe-ProNH2, slightly stimulatory when used alone, had no additive effect when used in combination with FPP and the methyl derivative of FPP had no bioactivity itself and did not inhibit responses to FPP. In marked contrast, pGlu-Gln-ProNH2 (Gln-FPP), which had no bioactivity when added to uncapacitated suspensions at 50-100 nM, significantly inhibited FPP's stimulation of capacitation and fertilizing ability in vitro. Furthermore, when Gln-FPP + FPP were added to capacitated suspensions, Gln-FPP prevented FPP's inhibition of spontaneous acrosome loss. Our recent studies have indicated that FPP and adenosine can elicit similar responses but appear to act at different sites. The fact that Gln-FPP inhibited responses to FPP, but not to adenosine, indicates that Gln-FPP is acting at an FPP-specific site. We, therefore, conclude that the specific structure of the FPP molecule is crucial for biological activity. Removal of the terminal amide group abolishes bioactivity and changes to the central amino acid can have significant functional consequences. Since Gln-FPP is a candidate intermediate peptide in the FPP biosynthetic pathway and has been identified in human semen, abnormality in prostate function could lead to release of Gln-FPP along with, or instead of, FPP. Our results suggest that the relative proportions of FPP and related peptides in seminal plasma could have a significant effect on fertility in vivo.

TCP-11, the product of a mouse t-complex gene, plays a role in stimulation of capacitation and inhibition of the spontaneous acrosome reaction

Tcp-11 is a candidate for a distorter gene within the t-complex on mouse chromosome 17; although t-complex genes appear to affect sperm function, relatively little is known about mechanisms whereby these genes might play a specific physiological role. We present evidence that the protein TCP-11 is found on the surface of mature epididymal spermatozoa. Although detected on both the acrosomal cap region of the head and the flagellum of acrosome-intact cells, it is absent from the heads of acrosome-reacted cells. When epididymal spermatozoa were incubated in the presence of anti-TCP-11 IgG Fab fragments for a total of 120 min and assessed using chlortetracycline fluorescence, we observed a stimulation of capacitation and an inhibition of spontaneous acrosome loss, suggestive of enhanced fertility compared with untreated suspensions. In vitro fertilization experiments confirmed that Fab-treated suspensions became fertile more quickly and then maintained high fertility. Because these responses were remarkably similar to those obtained using the TRH-related peptide FPP (fertilization promoting peptide; pGlu-Glu-ProNH2) and adenosine, we investigated responses to Fab fragments, FPP, and adenosine. Results indicated that the Fab fragments appear to work at the same extracellular site as FPP, one that is distinct from the adenosine site of action. Further evidence for this conclusion was obtained using pGlu-Gln-ProNH2, an FPP-related tripeptide known to competitively inhibit responses to FPP; as with FPP, pGlu-Glu-ProNH2 inhibited the stimulatory effect of Fab fragments in a concentration-dependent manner. From these results we suggest that TCP-11 may be the receptor for FPP and that the adenylate clyclase/cyclic AMP pathway may be the signal transduction pathway activated by interactions between extracellular effector molecules (e.g., Fab fragments or FPP acting as an agonist) and TCP-11. A mechanism such as this that promotes capacitation but inhibits spontaneous acrosome loss in vivo would play a very important role by helping to maximize the fertilizing potential of the few spermatozoa that reach the site of fertilization. The fact that there is a human homolog of Tcp-11 suggests that this gene could play an important role in regulation of human, as well as mouse, sperm function.

Three genes encoding zinc finger proteins on human chromosome 6p21.3: members of a new subclass of the Kruppel gene family containing the conserved SCAN box domain

Five genes encoding zinc finger proteins of the Cys2His2 (or Krüppel) family were identified by direct cDNA hybridization to YACs 753H12 and 638D7, which encompass a region of human chromosome 6p21.3 extending from just centromeric of the microsatellite marker D6S306 to telomeric of D6S1260. The genes span a distance of approximately 1750 kb. The complete cDNA sequence, genomic structure, and tissue distribution of three of the zinc finger proteins, LD65/ZNF165, ZNF192 (previously called LD5-1), and ZNF193, are described. The three zinc finger proteins do not contain either Krüppel-associated box (KRAB) A or KRAB B domain, present in about one-third of all Krüppel-type zinc finger proteins (E. J. Bellefroid et al., 1991, Proc. Natl. Acad. Sci. USA 88: 3608-3612). The three zinc finger proteins do contain the conserved SCAN box domain (A. J. Williams et al., 1995, J. Biol. Chem. 270: 22143-22152). SCAN boxes are found in eight other genes in the GenBank database, five of which are also in the Kruppel family of zinc finger proteins lacking KRAB A and B domains and thereby define a new subclass of zinc finger proteins. In addition, three polymorphisms were identified in ZNF192, one of the zinc finger proteins. One of the three polymorphisms, Pro163Leu, is the second proline in a proline cluster (PEPP) in a region separating the SCAN box from the zinc finger motifs.

Identification of a novel Krueppel-related zinc finger gene (ZNF184) mapping to 6p21.3

cDNA selection and exon trapping were performed on cosmids mapping to a region 3 Mb distal to HLA-A. Analysis of resulting fragments indicated the presence of two zinc finger transcripts, and one of these was used to isolate a partial cDNA (ZNF184) from a placental library. The second transcript contained additional sequence of the 5' end of the gene, extending the sequence to 2678 bp. Sequence analysis indicates that ZNF184 is a classical Krueppel zinc finger with 19 highly conserved zinc finger motifs at the C-terminus and a Krueppel associated box at the N-terminus of the protein. This gene encodes a 3.2-kb transcript that is highly expressed in testis and expressed at a moderate to low level in all other tissues tested. This zinc finger gene maps to a region approximately 200 kb distal to the microsatellite marker D6S105 and approximately 300 kb proximal to D6S1260.

Polyclonal origin of colonic adenomas in an XO/XY patient with FAP

It is widely accepted that tumors are monoclonal in origin, arising from a mutation or series of mutations in a single cell and its descendants. The clonal origin of colonic adenomas and uninvolved intestinal mucosa from an XO/XY mosaic individual with familial adenomatous polyposis (FAP) was examined directly by in situ hybridization with Y chromosome probes. In this patient, the crypts of the small and large intestine were clonal, but at least 76 percent of the microadenomas were polyclonal in origin.

The mouse t-complex gene, Tcp-11, is under translational control

The mouse t-complex is known to harbour genes which affect male fertility. Tcp-11 is a t-complex gene which is only expressed in male germ cells and from its position is a candidate for a distorter, one of the two types of genetic element involved in transmission ratio distortion. Antibodies raised to TCP-11 protein made in E. Coli were used on thin sections of testis and shown to recognise late spermatids. On Western blots the antibodies bound to a 68-kD protein present in protein extracts from testis. No specific signal could be detected using the antibody on protein extracts from other mouse tissues. Following gentle lysis of the germ cells and fractionation on sucrose gradients, all the material recognised by the anti-Tcp-11 antibody was found to be soluble and unassociated with any membrane fraction or organelle. A comparison of the time course of expression of the Tcp-11 mRNA and the TCP-11 protein revealed that expression of this gene is under translational control.

Characterization and mapping of the human SOX4 gene

The SOX genes comprise a large family related by homology to the HMG-box region of the testis-determining gene SRY. We have cloned and sequenced the human SOX4 gene. The open reading frame encodes a 474 amino acid protein, which includes an HMG-box. The non-box sequence is particularly rich in serine residues and has several polyglycine and polyalanine stretches. With somatic cell hybrids, human SOX4 has been mapped to Chromosome (Chr) 6p distal to the MHC region. There is no evidence for clustering of other members of the SOX1, -2, and -3 or SOX4 gene families around the SOX4 locus.

Efficiency and specificity of gene isolation by exon amplification

Exon amplification is an increasingly popular approach to the identification of transcribed sequences and will complement other strategies to isolate genes. We have used this system to amplify candidate exons from 32 cosmids, including 8 cosmids which span a well characterized 185-kb region of the human major histocompatibility class II region on Chromosome (Chr) 6. We have examined the efficiency, specificity, and reproducibility of the system in isolating exons from genes known to be present on particular cosmids and have determined the nature and frequency of artefact amplifications in routine cosmid screening. We were able to clone at least one exon from 88% (7/8) of all known genes tested (including exons which are differentially spliced) and obtained artefacts from 19% (6/32) of the cosmids tested. Such artefacts generally arise from the amplification of noncoding sequences flanked by regions with high homology to acceptor and donor splice junctions. We show that the exon amplification procedure can be used successfully with a wide variety of cosmids which have different numbers of genes and gene structures and describe several approaches to the characterization of novel exons cloned in this study.