Spatial-temporal Expression Patterns Research Articles

Expression analysis of two reverse duplicated small heat shock protein genes in rice (Oryza sativa L.)

The small heat shock protein (sHSP) chaperones are required for protecting cellular proteins from damage, as well as re-folding denatured proteins. This study was carried out to investigate the temporal-spatial expression patterns of two sHSP genes in rice. These two genes, named as Os16.9A and Os16.9B, are reverse duplicated genes that adjacently located on chromosome 1 and probably share the same or overlapping DNA region as a promoter. The interval sequence between the start codons of the two genes which are transcribed in opposite directions is only about 2.6 kb. Semi-quantitative RT-PCR was carried out to detect the expression of the two genes under normal growth conditions and different stress conditions. The expression patterns of the two genes were in detail investigated by using β-glucuronidase (GUS) reporter gene fusion system. Results showed that heat shock stress can induce high level expression of the two genes. Under normal growth conditions, Os16.9A and Os16.9B expressed in vegetative organs and young panicles. GUS staining combined with cytological observations showed that the two genes expressed mainly in the vascular tissues of roots, stems and young panicles, implicating that Os16.9A and Os16.9B play important roles not only for heat shock response, but also for normal development in rice.

Genome-wide analysis suggests divergent evolution of lipid phosphotases/phosphotransferase genes in plants.

Genes of the LPPT (lipid phosphatase/phosphotransferase) family play important roles in lipid phosphorous transfer and triacylglycerol accumulation in plants. To provide overviews of the plant LPPT family and their overall relationships, here we carried out genome-wide identifications and analyses of plant LPPT family members. A total of 643 putative LPPT genes were identified from 48 sequenced plant genomes, among which 205 genes from 14 plants were chosen for further analyses. Plant LPPT genes belonged to three distinctive groups, namely the LPT (lipid phosphotransfease), LPP (lipid phosphatase), and pLPP (plastidic lipid phosphotransfease) groups. Genes of the LPT group could be further partitioned into three groups, two of which were only identified in terrestrial plants. Genes in the LPP and pLPP groups experienced duplications in early stages of plant evolution. Among 17 Zea mays LPPT genes, divergence of temporal-spatial expression patterns was revealed based on microarray data analysis. Peptide sequences of plant LPPT genes harbored different conserved motifs. A test of Branch Model versus One-ratio Model did not support significant selective pressures acting on different groups of LPPT genes, although quite different nonsynonymous evolutionary rates and selective pressures were observed. The complete picture of the plant LPPT family provided here should facilitate further investigations of plant LPPT genes and offer a better understanding of lipid biosynthesis in plants.

Analysis of spatial-temporal gene expression patterns reveals dynamics and regionalization in developing mouse brain.

Allen Brain Atlas (ABA) provides a valuable resource of spatial/temporal gene expressions in mammalian brains. Despite rich information extracted from this database, current analyses suffer from several limitations. First, most studies are either gene-centric or region-centric, thus are inadequate to capture the superposition of multiple spatial-temporal patterns. Second, standard tools of expression analysis such as matrix factorization can capture those patterns but do not explicitly incorporate spatial dependency. To overcome those limitations, we proposed a computational method to detect recurrent patterns in the spatial-temporal gene expression data of developing mouse brains. We demonstrated that regional distinction in brain development could be revealed by localized gene expression patterns. The patterns expressed in the forebrain, medullary and pontomedullary, and basal ganglia are enriched with genes involved in forebrain development, locomotory behavior, and dopamine metabolism respectively. In addition, the timing of global gene expression patterns reflects the general trends of molecular events in mouse brain development. Furthermore, we validated functional implications of the inferred patterns by showing genes sharing similar spatial-temporal expression patterns with Lhx2 exhibited differential expression in the embryonic forebrains of Lhx2 mutant mice. These analysis outcomes confirm the utility of recurrent expression patterns in studying brain development.

NFI-C2 temporal-spatial expression and cellular localization pattern during tooth formation.

Currently, little is known regarding critical signaling pathways during later stages of tooth development, especially those associated with root formation. Nfi-c null mice, lacking molar roots, have implicated the transcription factor NFI-C as having an essential role in root development. Previously, we identified three NFI-C isoforms expressed in dental tissues with NFI-C2 being the major transcript. However, the expression pattern of the NFI-C2 protein is not characterized. In this study we performed in situ hybridization and immunohistochemistry using isoform specific probes. We show the production of a NFI-C2 peptide antibody, its characterization, the temporal-spatial expression pattern of the NFI-C2 protein during odontogenesis and sub-cellular localization in dental cells. Moderate NFI-C2 staining, as early as bud stage, was detected mostly in the condensing dental ectomesenchyme. This staining intensified within the dental pulp at later stages culminating in high expression in the dentin producing odontoblasts. The dental epithelium showed slight staining until cytodifferentiation of enamel organ into ameloblasts and stratum intermedium. During root formation NFI-C2 expression was high in the Hertwig's epithelial root sheath and later was found in the fully developed root and its supporting tissues. NFI-C2 cellular staining was cytosolic, associated with the Golgi, and nuclear. These data suggest a broader role for NFI-C during tooth formation than limited to root and periodontal ligament development.

Abstract 18584: Decoding the Regulatory LncRNAs in Neonatal Heart During Perinatal Circulatory Transition

Background: Fetal to neonatal transition of heart is an elaborate process, during which, neonatal cardiomyocytes undergo functional maturation and terminal exit from the cell cycle. However, transcriptome programming in neonatal cardiac chambers during perinatal stages is understudied. In particular, the changes in long non-coding RNAs (lncRNAs) in neonatal heart have not been explored. Objective: To achieve transcriptome-wide analysis of lncRNAs in neonatal left ventricle (LV) and right ventricle (RV) during maturation stages using deep RNA-Sequencing Methods: Deep RNA-sequencing was performed on male newborn mouse (C57 BL) LV and RV at 3 time points of perinatal circulatory transition: P0, P3 and P7. Reads were mapped to mouse genome (mm10). The lncRNAs annotated in NONCODE database were identified. Differentially expressed lncRNAs were defined as those with coefficient of variation ≥0.2, at a false discovery rate ≤0.05, and expressed at ≥3 RPKM in at least one sample. Correlated lncRNAs/ gene pairs were identified using Pearson’s (r2≥0.8, P≤0.05). A subset of LncRNAs/gene expression was validated using qRT-PCR. Results: Out of the 70, 983 observed unique lncRNAs, approximately 7000 were identified exhibiting significant variation during maturation windows with highly spatial-temporal dependent expression patterns, including approximately 5000 known and 2000 novel lncRNAs. Notably, 20% of these lncRNAs were located within 50 KB of a protein coding gene. Out of a total of 2400 lncRNAs/gene pairs, 10 % exhibited significantly concordant (lncRNA/gene) expression patterns. These correlated genes were significantly enriched in metabolism, cell cycle and contractility functional ontology. Interestingly, some of these lncRNAs exhibited concordance with their neighboring gene in human tissues with congenital heart defects, suggesting conserved, potentially significant, regulatory function. Conclusions: Transcriptome programming during neonatal heart maturation involves global changes in lncRNAs. Their expression concordance with neighboring protein coding genes implicates potential important regulatory role of lncRNAs in neonatal heart chamber specification and congenital diseases.

Identification and expression analysis of a heat-shock protein 70 gene in Polycelis sp.

Heat-shock protein 70 (HSP70) is ubiquitously found in a variety of organisms and plays an important role in cytoprotection, environmental monitoring, and disease resistance. In this study, the full-length complementary DNA (cDNA) of hsp70 from planarian Polycelis sp. was first cloned using rapid amplification of cDNA ends (RACE). The expression levels of Pyhsp70 were analyzed in the presence of various stressors by real-time PCR, and its temporal-spatial expression patterns were also examined in both intact and regenerative animals by whole-mount in situ hybridization. The results show that (1) the deduced amino acid sequence of Pyhsp70 includes three typical HSP70 family signature motifs and is highly conserved during evolution; (2) Pyhsp70 expression is induced by prolonged starvation, tissue damage, and ionic liquid but inhibited by high or low temperatures; and (3) Pyhsp70 mRNA is mainly expressed in the head peripheral region and in the regenerating blastema during regeneration. These results suggest that the highly expressed Pyhsp70 gene may contribute to enhance cytoprotection and tolerance against stress-induced molecular damage, and the migration of neoblasts to the wound, which might also be involved in the proliferation and differentiation of neoblasts. Our work provides basic data for the study of stress responses and regenerative mechanism in freshwater planarians.

Expression analysis of integrin β1 isoforms during zebrafish embryonic development

Integrins are a superfamily of the major metazoan receptors for cell–cell and cell–extracellular matrix adhesion. Integrins and their ligands play critical roles in a variety of fundamental cellular processes. Integrins are heterodimeric cell surface glycoproteins comprised of non-covalently bound α- and β-subunits. A variety of integrin subunits have been identified in mouse, chicken, zebrafish, Xenopus laevis and other vertebrates. In zebrafish multiple integrin β1 homologs have been identified. However, zebrafish embryo is a largely untapped model for analyzing integrin β1 isoforms temporal-spatial expression pattern, function and its relevance to human disease in whole animal level. Currently, we systematically analyzed the expression pattern of zebrafish integrin β1 including integrin beta 1a (itgb1a), integrin beta 1b (itgb1b), integrin beta 1b.1 (itgb1b.1), and integrin beta 1b.2 (itgb1b.2) at embryo stage using whole amount in situ hybridization. We show itgb1a, itgb1b and itgb1b.1 were maternally expressed in zygote, cleavage and blastula periods, while itgb1b.2 was not detectable in the corresponding stages. A more tissue specific pattern emerges during organogenesis, including heart expression for itgb1a, myotome borders for itgb1b, intestinal epithelium for itgb1b.1, and branchial arch for itgb1b.2. All are similarly expressed in the early embryonic epidermis and notochord. Additionally, itgb1a, itgb1b and itgb1b.2 shared the common expression in otic vesicle. Our study provides new insight into the integrin β1 expression and the use of this model organism to tackle future studies on the role of integrin β1 in embryo development.

TUBULINOPATHIES IN MALFORMATIONS OF THE CEREBRAL CORTEX

<h3>Aims</h3> To further characterise the ‘tubulinopathy’ spectrum of overlapping brain malformations (including lissencephaly, polymicrogyria and mildly simplified gyral patterning) that arise from tubulin gene variations affecting neuronal proliferation, migration and post-migrational organisation during cerebral cortex development. <h3>Method</h3> A cohort of affected cases (n=13) with mild to unaffected cerebral cortex patterning, but with highly recognisable basal ganglia, corpus callosal and cerebellar malformations, were screened for gene-variations in a number of human brain-expressed tubulin genes. <h3>Results</h3> We describe two unrelated individuals with mildly simplified gyration and infantile-onset epilepsy, harbouring de novo variants that affect adjacent amino acids in a novel tubulinopathy gene, TUBB2A. We also report a further four mutations in TUBA1A, TUBB2B and TUBB3 (historically associated with lissencephaly, polymicrogyria and polymicrogyria/congenital fibrosis of the extraocular muscles respectively) in individuals with normal gyration but extra-cortical abnormalities characteristic of tubulin gene involvement. <h3>Conclusion</h3> We describe a highly stereotyped brain phenotype caused by mutations in four different genes (TUBA1A, TUBB2B, TUBB3 and a novel gene, TUBB2A), sharing high sequence homologies but with distinct spatial-temporal expression patterns. All beta-tubulins highly expressed during cerebral cortex development are now associated with brain malformations.

Spatial-temporal expressions of Crumbs and Nagie oko and their interdependence in zebrafish central nervous system during early development

A vast number of apicobasal polarity proteins play essential roles in the polarization and morphogenesis of the neuroepithelia. Crumbs (Crb) type I transmembrane cell–cell adhesion proteins are among these proteins. Five crb genes have been identified in zebrafish. However, their expressional and functional differences during early neural development remain to be fully elucidated. Here, we study the spatial-temporal expression patterns and functions of Crb1, Crb2a, and Crb2b in the central nervous system (CNS) during the neurulation period. We show that: 1, the optic vesicle and undifferentiated retinal neuroepithelium only express Crb2a; 2, Crb1 and Crb2a expressions overlap extensively in the undifferentiated neural tube epithelium; 3, Crb2b expression is the weakest of the three and is restricted to the ventral-most regions of the anterior CNS; and 4, Nok and Crb proteins require each other for their apical localization in neuroepithelium. The commencements of Crb1, Crb2a, and Crb2b expressions follow a spatial-temporal spread from anterior to posterior and from ventral to dorsal and lag behind that of adherens junction components, such as ZO-1 and actin bundles. Genetic and morpholino suppression analyses suggest that in regions where these Crb expressions overlap, they are functionally redundant in maintaining apicobasal polarity of the undifferentiated neuroepithelium.

Growth Differentiation Factor 5 Regulation in Bone Regeneration

Growth differentiation factor 5 (GDF5) is a member of the bone morphogenic protein (BMP) family and plays critical roles in organ development processes including bone, cartilage, ligament, and joint formation. GDF5 is expressed in the cartilage primordium in the early limb development, and in the interzone of joint formation sites. GDF5 is also observed in adult tissue and cell lines. This spatialtemporal expression pattern of GDF5 proves its essential role in the formation of bone and cartilage. Similar to other members of BMPs, the signaling cascade of GDF5 is originated through binding to type I and type II receptors and thus regulating the downstream intracellular biochemical processes. Mutations of GDF5 are associated with several human and animal diseases that are characterized by skeletal deformity such as short digits and short limbs. In vitro and in vivo studies demonstrated that overexpression of GDF5 or administration of recombinant protein promotes chondrogenesis and osteogenesis. Moreover, a promising feature of GDF5 is osteoinduction, which is used in tissue engineering for bone repair with or without a carrier in animal platforms and in human preclinical settings. The exciting results signify that GDF5 is a compelling candidate for bone tissue engineering by enhancing osteogenesis and angiogenesis. In this review, we will focus the discussion on the basic structure, signaling pathways, function in cartilage and bone formation, and potential clinical application of GDF5 in bone tissue regeneration.

FOXO3a/p27kip1 expression and essential role after acute spinal cord injury in adult rat

FOXO3a (Forkhead Class box O3a), as an important direct target of the phosphatidylinositol 3-kinase (PI3K)/protein B (Akt) pathway, which regulates the cell survival and the cell-cycle progression. Recent reports showed that FOXO3a could inhibit cell-cycle progression at the G1/S transition by controlling transcription of the cyclin-dependent kinase inhibitor p27(kip1) , which is also a key regulator of the mammalian neurogenesis. To elucidate the expression and role of FOXO3a in nervous system lesion and repair, we performed an acute spinal cord contusion injury (SCI) model in adult rats, which showed a temporal-spatial expression pattern of FOXO3a. Temporally, FOXO3a protein level significantly reduced day 3 after injury, and following FOXO3a down-regulation, p27(kip1) protein and mRNA levels were also decreased after injury. Spatially, decreased levels of FOXO3a and p27(kip1) were predominant in astrocytes, which were regenerating axons and largely proliferated after injury. Furthermore in vitro, Western blot analysis, RT-PCR, and immunofluorescence staining analysis demonstrated the relationship between FOXO3a and p27(kip1) in primary astrocytes. FOXO3a modulated the cell cycle by transcriptional regulation of p27(kip1) in astrocytes. Administration of the PI3K pharmacological inhibitor LY294002 abrogated this effect by regulating FOXO3a and p27(kip1) expression and subcellular localization. These results suggest that decreased levels of FOXO3a and p27(kip1) in spinal cord are involved in axonal regeneration and the proliferation of glial cells after SCI.

Overexpression of glucosyltransferase UGT85A1 influences trans-zeatin homeostasis and trans-zeatin responses likely through O-glucosylation

Trans-zeatin is a kind of cytokinins that plays a crucial role in plant growth and development. The master trans-zeatin O-glucosyltransferase of Arabidopsis thaliana, UGT85A1, has been previously identified through biochemical approach. To determine the in planta role of UGT85A1 gene, the characterization of transgenic Arabidopsis plants overexpressing UGT85A1 was carried out. Under normal conditions, transgenic Arabidopsis did not display clearly altered phenotypes. A remarkable alteration is that the accumulation level of the trans-zeatin O-glucosides was significantly increased in UGT85A1 overexpressing transgenic Arabidopsis, while other forms of cytokinins kept the similar concentrations compared to the wild type. When treated with exogenously applied trans-zeatin, UGT85A1 overexpressing Arabidopsis showed much less sensitivity to trans-zeatin in primary root elongation and lateral root formation. Meanwhile, the chlorophyll content of detached leaves of transgenic Arabidopsis was much lower than wild type. Studies of spatial-temporal expression patterns showed that UGT85A1 was mainly expressed in the early seedlings and developing seeds. Analysis of subcellular localization suggested that UGT85A1 was localized to cytoplasm and nucleus. Taken together, our data suggest that overexpression of Arabidopsis glucosyltransferase UGT85A1 influences trans-zeatin homeostasis and trans-zeatin responses likely through O-glucosylation in planta.

Identification of novel members reveals the structural and functional divergence of lepidopteran-specific Lipoprotein_11 family

30K proteins (30KPs) are classified into the lepidopteran-specific Lipoprotein_11 family. They are involved in various physiological processes such as energy storage, embryonic development, and immune response in the silkworm. To date, 30KPs were only found in Bombyx mori and Manduca sexta. Moreover, the C-termini of ENF peptide binding proteins (ENF-BPs) show similarity to 30KPs. ENF peptides are multifunctional insect cytokines and involved in growth regulation and defense reaction, whereas ENF-BPs act as active regulators of ENF peptides. In order to get insights into this gene family in Lepidoptera, we performed an extensive survey of lepidopteran-derived genome and EST datasets. We identified 73 30KP homologous genes in 12 lepidopteran species, of which 56 are novel members. The structural and phylogenetic analyses revealed that these genes could be classified into three groups: ENF-BP genes, typical 30KP genes, and serine/threonine-rich 30KP (S/T-rich 30KP) genes. The C-terminal regions are common to all the three subfamilies, but the N-termini are highly variable. We found a novel subfamily of Lipoprotein_11 and named it S/T-rich 30KP according to its exclusive S/T-rich domain in the N terminus. ENF-BP was also found to contain a special domain in the N terminus, which is homologous to Pp-0912 of Pseudomonas putida. Microarray data and semi-quantitative RT-PCR showed that the three groups have their respective temporal-spatial expression patterns. S/T-rich 30KP genes have enriched expression in the mature testis and might be involved in spermiogenesis or fertilization. Typical 30KP genes are expressed mainly in the fat body and integument at the larvae and pupae stages. ENF-BP genes are expressed predominantly in the hemocyte. The differential spatial-temporal expression profiles revealed the functional divergence of three Lipoprotein_11 subfamilies.

The expression pattern of FHL2 during mouse molar development

Four and a half LIM domains 2 (FHL2) functions as a transcriptional co-activator or co-repressor in a cell-type-specific manner. As a positive regulator, FHL2 plays an important role in osteoblast differentiation and bone formation. Our previous study showed that FHL2 was expressed in odontoblasts in mature human teeth under normal and pathological conditions. The purpose of this study was to investigate the spatial-temporal expression patterns of FHL2 at different stages of mouse molar development by immunohistochemistry. Our results showed that at the bud and cap stage, FHL2 was expressed both in enamel organ and the underlying mesenchyme. At the early bell stage, FHL2 appeared in the inner and outer enamel epithelium, stratum intermedium and the secondary enamel knot. Positive staining gradually converged at the cusps of dental papilla. At the late bell stage, FHL2 was expressed in the terminal differentiated ameloblasts and odontoblasts and stratum intermedium. At the postnatal day, FHL2 was detected in the secretory and mature ameloblasts and odontoblasts and mature enamel, and gradually appeared at Hertwig's epithelial root sheath and periodontal tissues. The spatial-temporal expression patterns of FHL2 from the bud stage to the postnatal day (13.5) suggested that during tooth development, FHL2 might play an important role in ameloblast and odontoblast differentiation, secretion of enamel and dentin matrix, mineralization of enamel, molar crown morphogenesis, as well as root formation.

Expression patterns of amelogenin and enamelin in developing mouse tooth germs

To invesitgate the expression patterns of amelogenin and enamelin in the developing tooth germs. Mandible sections of postnatal day 1, 3, 7 and 14 mouse were prepared, immunohistochemical analysis and reverse transcriptase polymerase chain reaction (RT-PCR) were performed to detect the expression patterns of amelogenin and enamelin in mandibular first molars. Amelogenin was observed in the cytoplasm of secretory ameloblasts and the whole enamel matrix layer. It was also transiently expressed in the odontoblasts of postnatal day 1 molars. Enamelin proteins were observed in the enamel layer deposited by secretory ameloblasts, especially intense beneath the ameloblast process and dentino-enamel junction. The mRNA levels of both amelogenin and enamelin were highest on postnatal day 7 (the ratio to glyceraldehyde phosphate dehydrogenase of amelogenin and enamelin: 0.813 ± 0.085 and 0.799 ± 0.064, respectively, P < 0.05). Amelogenin and enamelin were enamel matrix proteins predominately expressed by secretory ameloblasts. The temporal-spatial expression patterns of amelogenin and enamelin indicate the important roles they played in amelogenesis and biomineralization.

Alterations in TCF7L2 expression define its role as a key regulator of glucose metabolism

Genome-wide association studies (GWAS) have consistently implicated noncoding variation within the TCF7L2 locus with type 2 diabetes (T2D) risk. While this locus represents the strongest genetic determinant for T2D risk in humans, it remains unclear how these noncoding variants affect disease etiology. To test the hypothesis that the T2D-associated interval harbors cis-regulatory elements controlling TCF7L2 expression, we conducted in vivo transgenic reporter assays to characterize the TCF7L2 regulatory landscape. We found that the 92-kb genomic interval associated with T2D harbors long-range enhancers regulating various aspects of the spatial-temporal expression patterns of TCF7L2, including expression in tissues involved in the control of glucose homeostasis. By selectively deleting this interval, we establish a critical role for these enhancers in robust TCF7L2 expression. To further determine whether variation in Tcf7l2 expression may lead to diabetes, we developed a Tcf7l2 copy-number allelic series in mice. We show that a null Tcf7l2 allele leads, in a dose-dependent manner, to lower glycemic profiles. Tcf7l2 null mice also display enhanced glucose tolerance coupled to significantly lowered insulin levels, suggesting that these mice are protected against T2D. Confirming these observations, transgenic mice harboring multiple Tcf7l2 copies and overexpressing this gene display reciprocal phenotypes, including glucose intolerance. These results directly demonstrate that Tcf7l2 plays a role in regulating glucose tolerance, suggesting that overexpression of this gene is associated with increased risk of T2D. These data highlight the role of enhancer elements as mediators of T2D risk in humans, strengthening the evidence that variation in cis-regulatory elements may be a paradigm for genetic predispositions to common disease.

Expression and role of Elovl4 elongases in biosynthesis of very long-chain fatty acids during zebrafish Danio rerio early embryonic development

Elovl4 is a fatty acyl elongase that participates in the biosynthesis of very long-chain fatty acids (≥ C24), which are relatively abundant in skin (saturated chains), or retina, brain and testes (polyunsaturated chains) of mammals. In the present study we characterised two Elovl4 proteins, Elovl4a and Elovl4b, from zebrafish Danio rerio, and investigated their expression patterns during embryonic development. Heterologous expression in baker's yeast showed that both zebrafish Elovl4 proteins efficiently elongated saturated fatty acids up to C36, with 26:0 appearing the preferred substrate as reported for human ELOVL4. Interestingly, activity for the elongation of PUFA substrates was only shown by Elovl4b, which effectively converted eicosapentaenoic (20:5n-3) and arachidonic (20:4n-6) acids to elongated polyenoic products up to C36. Furthermore, zebrafish Elovl4b may be involved in the biosynthesis of docosahexaenoic acid (22:6n-3, DHA) as it had the capacity to elongate 22:5n-3 to 24:5n-3 which can be subsequently desaturated and chain shortened to DHA in peroxisomes. The distinct functional roles of zebrafish Elovl4 proteins were also reflected in their spatial–temporal expression patterns during ontogeny. Analyses by whole-mount in situ hybridisation in zebrafish embryos showed that elovl4a was expressed in neuronal tissues (wide-spread distribution in the head area), with elovl4b specifically expressed in epiphysis (pineal gland) and photoreceptor cells in the retina. Similarly, tissue distribution in adults revealed that elovl4a transcripts were found in most tissues analysed, whereas elovl4b expression was essentially restricted to eye and gonads. Overall, the results suggest that zebrafish elovl4b resembles other mammalian orthologues in terms of function and expression patterns, whereas elovl4a may represent an alternative elongase not previously described in vertebrates.

Expression of the tyrosine kinase discoidin domain receptor 1 (DDR1) in human central nervous system myelin

During development of the mouse brain, the protein kinase discoidin domain receptor 1 (DDR1) is present prenatally in neurons of the proliferative areas, and postnatally, DDR1 expression is no longer detected in neurons, but a spatial–temporal expression pattern in oligodendrocytes that overlaps with the dynamics of the myelination process is detected. Notably, oligodendrocytic DDR1 expression is upregulated in mice during experimentally induced remyelination. Recently, we demonstrated that DDR1 expression is high in human brain and that there is an association between the gene and schizophrenia in a case–control study. However, data regarding expression of DDR1 in the human brain are scarce. Here, we describe the expression pattern of DDR1 in the human adult cerebral cortex. Using several immunohistological techniques and in situ hybridization, we identified DDR1 in the following: a) myelin, b) capillary endothelial cells in the gray as well as white matter, and c) in the soma of some oligodendrocytes and astrocytes in the white matter. The most important overall finding in this study was that DDR1 is present in myelin and is expressed by oligodendrocyte cells. We detected the presence of DDR1 mRNA and protein in myelin and observed that DDR1 co-localized with the classical myelin basic protein (MBP). Moreover, we found a strong positive correlation between expression levels of DDR1 and two myelin-associated genes, myelin-associated glycoprotein (MAG) and oligodendrocyte transcription factor 2 (OLIG2). These observations suggest that DDR1 could be an important constituent of myelin. Because defects in myelination are linked to several mental disorders such as schizophrenia, the function of DDR1 in the process of myelination warrants further investigation.

Diversity of sensory guanylate cyclases in teleost fishes

Teleost fishes like medaka fish (Oryzias latipes), zebrafish (Danio rerio), and pufferfish (Fugu rubripes) contain in their genomes a larger number of guanylate cyclases and guanylate cyclase-activating proteins than mammals. Based on amino acid sequence alignments a group of transmembrane sensory guanylate cyclases can be identified, which are mainly if not exclusively expressed in sensory organs like the retina and olfactory tissue. Retina specific guanylate cyclases and guanylate cyclase-activating proteins in the zebrafish show dynamic changes in their spatial-temporal expression patterns and transcripts of the corresponding genes appear coincidently with the beginning of cone cell maturation at 3 days post-fertilization. Expression patterns of the guanylate cyclase signaling systems during larval development are correlated with the special habitat challenges of zebrafishes in the wild.

New Candidate Genes Identified for Controlling Mouse Gonadal Sex Determination and the Early Stages of Granulosa and Sertoli Cell Differentiation1

Mammalian gonadal sex-determining (GSD) genes are expressed in a unique population of somatic cells that differentiate into granulosa cells in XX gonads or Sertoli cells in XY gonads. The ability to efficiently isolate these somatic support cells (SSCs) during the earliest stages of gonad development would facilitate identifying 1) new candidate GSD genes that may be involved in cases of unexplained abnormal gonad development and 2) genes involved in the earliest stages of granulosa and Sertoli cell differentiation. We report the development of a unique mouse carrying two transgenes that allow XX and XY mice to be distinguished as early as Embryonic Day 11.5 (E11.5) and allow SSCs to be isolated from undifferentiated (E11.5) and early differentiated (E12.5) fetal gonads. The Mouse Genome 430v2.0 GeneChip (Affymetrix) was used to identify transcripts exhibiting a sexual dimorphic expression pattern in XX and XY isolated SSCs. The analysis revealed previously unidentified sexually dimorphic transcripts, including low-level expressed genes such as Sry, a gene not identified in other microarray studies. Multigene real-time PCR analysis of 57 genes verified that 53 were expressed in fetal gonads in a sexually dimorphic pattern, and whole-mount in situ hybridization analysis verified 4930563E18Rik, Pld1, and Sprr2d are expressed in XX gonads, and Fbln2, Ppargc1a, and Scrn1 are expressed in XY gonads. Taken together, the data provide a comprehensive resource for the spatial-temporal expression pattern of genes that are part of the genetic network underlying the early stages of mammalian fetal gonadal development, including the development of granulosa and Sertoli cells.