Project description:Gap junctions and purinergic P2 receptors (P2Rs) can be regarded as belonging to a common functional unit, given that they are involved in the transmission of calcium signals between cells. We have previously shown that deletion of the Gja1 gene alters expression levels of numerous genes encoding proteins with diverse functions, including purinergic, P2Rs, and have found that genes synergistically or antagonistically expressed in wildtype tissues are more prone to be similarly or oppositely regulated in Cx43-nulls. We have now explored the use of coordination analysis of gene expression as a strategy to identify interlinked genes encoding functionally related proteins and used pull-downs to evaluate their interlinkage. Our findings indicate that, in brain and in cultured astrocytes, several of these co-expressed genes encode proteins that are components of P2R signal transduction pathways and/or directly interact with these receptors, including the gap junction protein connexin43 (Cx43) and connexin45 (Cx45), as well as pannexins. It is proposed that coordination analysis of gene expression may provide a novel unbiased strategy for the identification of proteins belonging to supramolecular complexes. Keywords: genetic modification
Project description:Trigeminal ganglion (TG) is the first station of sensory pathways in the orofacial region. The TG neurons communicate with satellite glial cells (SGCs), macrophages and other cells forming a functional unit that is responsible for processing of orofacial sensory information. Purinergic signaling, one of the most widespread autocrine and paracrine pathways, plays a crucial role in intercellular communication. The multidirectional action of purinergic signaling in different cell types contributes to the neuromodulation and orofacial sensation. To fully understand the purinergic signaling in these processes, it is essential to determine the shared and unique expression patterns of genes associated with purinergic signaling in different cell types. Here, we performed single-cell RNA sequencing of 22,969 cells isolated from normal mouse TGs. We identified 18 distinct cell populations, including 6 neuron subpopulations, 3 glial subpopulations, 7 immune cell subpopulations, fibroblasts, and endothelial cells. We also revealed the transcriptional features of genes associated with purinergic signaling, including purinergic receptors, extracellular adenosine triphosphate (eATP) release channels, eATP metabolism-associated enzymes, and eATP transporters) in each cell type. Our results have important implications for understanding and predicting the cell type-specific roles of the purinergic signaling in orofacial signal processing in the trigeminal primary sensory system.
Project description:<p>Sertoli cell-only syndrome is severe form of human male infertility in which most seminiferous tubules appear to lack all spermatogenic cells, including spermatogonial stem cells (SSCs). However, a few small tubule segments of some patients have active spermatogenesis and, thus, functional stem cell niches and SSCs. Normally SSCs replicate, migrate and refill adjacent empty niches, but this does not appear to occur in SCO syndrome. We hypothesized that this failure occurs because most niches are dysfunctional. As Sertoli cells are essential to formation of these niches, we used RNAseq to compare the transcriptomes of human testes with qualitatively normal (complete) spermatogenesis (n=4) with the transcriptomes of human testes with SCO syndrome (n=7). We then focused our analysis on the expression of transcripts that bioinformatic analyses identified as Sertoli cell signature transcripts. Results show that Sertoli cells in SCO testes express abnormally low levels of GDNF, FGF8 and BMP4, all of which are important regulators of mouse SSCs and/or progenitor spermatogonia. Sertoli cells in SCO testes express significantly reduced levels of transcripts for proteins that polarize the Sertoli cell plasma membrane and regulate the trafficking of cell adhesion and gap junction proteins in and out of that plasma membrane.</p>
Project description:Purinergic P2 receptors are critical regulators of several functions within the vascular system, including platelet aggregation, vascular inflammation and vascular tone. A role for ATP release and P2Y receptors in angiogenesis has been implicated, however, the involvement of purinergic signalling in endothelial sprouting and vascular growth remains poorly understood. Here, we demonstrate that blood vessel growth is controlled by P2Y2 receptors. Inhibition of P2Y2 using a selective antagonist or modulation of P2Y2 receptor expression significantly influenced sprouting and vascular tube formation. Mechanistically, overexpression of P2Y2 in endothelial cells resulted in increased expression of the pro-angiogenic molecules CXCR4, CD34 and angiopoietin-2, while expression of Tie2 and VEGFR-2 decreased. Interestingly, elevated P2Y2 expression caused constitutive phosphorylation of ERK1/2 and VEGFR-2. However, stimulation of cells with the P2Y2 agonist UTP did not influence sprouting unless P2Y2 was constitutively expressed, indicating that enhanced receptor expression, and not activation, is the primary trigger for angiogenesis. Our data suggest that P2Y2 receptors have an essential function in angiogenesis through cross-talk of P2Y2 and VEGFR-2 and that P2Y2 may represent a therapeutic target to regulate blood vessel growth.
Project description:Establishment of left-right (LR) asymmetry occurs shortly after gastrulation and utilizes a cascade of events. In the mouse, LR symmetry is broken at the node, involves signal relay to the lateral plate, and results in asymmetric organ morphogenesis. How information transmits from the node to the lateral plate remains unclear. Noting that embryos lacking Sox17 exhibit defects in both gut endoderm formation and LR patterning, we investigated a connection between these two processes. We noted an endoderm-specific absence of the critical gap junction component, Connexin43, in Sox17 mutants. Dye-coupling experiments revealed planar gap junction coupling across the gut endoderm in wild-type but not mutant embryos. The role for gap junction communication in LR patterning was confirmed by pharmacological inhibition. Collectively, our data demonstrate communication across gap junctions in gut endoderm as a mechanism for information relay between node and lateral plate critical for the establishment of LR asymmetry in mice. Total RNA isolated from embryonic regions of wild-type embryos at EHF stages, three samples per well, in triplicates
Project description:Type of Experiment: 1) Profiles of Osteoblast vs. osteocyte in vitro; 2) Profiles of osteoblast low density vs. confluency in vitro; 3) Profiles of osteocyte with gap junction vs. without gap junction. Experimental factors: 1) 2T3 osteoblast cells at low density expressed extensive filopodia, reminiscent of early osteoblast precursors and similar to MLO-Y4 dendritic processes. 2) MLO-Y4 osteocytes at low vs. high density represent the genes that are changed in a highly connected network vs. low connected network. The number of hybridizations performed: Triplicate hybridizations for each status. Keywords = Osteoblast Keywords = Osteocyte
Project description:One way by which astrocytes modulate oligodendrocytes’ activity is by delivering neurotransmitters and leukemia inhibitory factor (Lif) in the medium that bind oligodendrocyte receptors. Most of these receptors are involved in intercellular Ca2+-signaling (ICS). However, not much is known about the interactions between myelination (MYE) and ICS genes and how astrocyte nearness modulates the oligodendrocyte genomic myelination fabric. We profiled the transcriptomes of immortalized oligodendrocyte precursor cells (Oli-neu) when cultured alone or co-cultured with cortical astrocytes. The astrocytes were plated in cell culture insert systems that did not allow formation of gap junction channels with oligodendrocytes but permitted exchange of soluble factors via the culture medium. Remarkably, astrocyte proximity induced a larger increase of the overall expression level and interlinkage of MYE genes than the differentiating 10d treatment with 1 mM dibutyryl cAMP that turns Oli-neu cells into myelin-associated glycoprotein-positive oligodendrocyte-like cells. Moreover, more MYE and ICS genes were turned on and fewer turned off by astrocyte proximity than by differentiating treatment. Lif receptor was up-regulated by astrocyte proximity but not by the differentiating treatment. We have identified the responsible transcriptomic networks by which the intercellular ICS gene web controls MYE gene web, with genes encoding the gap junction proteins (connexins, Cx) Cx29, Cx32 and Cx47 playing central roles. The novel Prominent Gene Analysis (that refines iteratively the functional webs to optimize the interconnectivity and expression stability of the associated genes) was used to select and rank the most relevant MYE and ICS genes and build the corresponding gene webs. Determine the modifications of the myelination transcriptome induced in Oli- neu control cells by differentiating treatment and proximity of cortical astrocytes. Four culture dishes of each of control, differentiated and in the astrocyte proximity Oli-neu cells were profiled using Duke mouse 30K and 36k oligonucleotide arrays in the "multiple yellow" hybrization design.
Project description:The atypical chemokine receptor 3 (ACKR3) plays a pivotal role in directing the migration of various cellular populations and its over-expression in various tumors promotes cell proliferation and invasiveness. The intracellular cellular pathways transducing ACKR3-dependent effects remain poorly characterized, an issue we addressed by characterizing the the interactome of recombinant ACKR3 expressed in HEK293T cells. Among the ACKR3-interacting proteins identified, we focused on the gap junction protein Connexin 43 (Cx43).
Project description:Verma2016 - Ca(2+) Signal Propagation Along Hepatocyte Cords
This model is described in the article:
Computational Modeling of
Spatiotemporal Ca(2+) Signal Propagation Along Hepatocyte
Cords.
Verma A, Makadia H, Hoek JB,
Ogunnaike BA, Vadigepalli R.
IEEE Trans Biomed Eng 2016 Oct; 63(10):
2047-2055
Abstract:
The purpose of this study is to model the dynamics of
lobular Ca(2+) wave propagation induced by an extracellular
stimulus, and to analyze the effect of spatially systematic
variations in cell-intrinsic signaling parameters on sinusoidal
Ca(2+) response.We developed a computational model of lobular
scale Ca(2+) signaling that accounts for receptor- mediated
initiation of cell-intrinsic Ca(2+) signal in hepatocytes and
its propagation to neighboring hepatocytes through gap
junction-mediated molecular exchange.Analysis of the
simulations showed that a pericentral-to-periportal spatial
gradient in hormone sensitivity and/or rates of IP3 synthesis
underlies the Ca(2+) wave propagation. We simulated specific
cases corresponding to localized disruptions in the graded
pattern of these parameters along a hepatic sinusoid.
Simulations incorporating locally altered parameters exhibited
Ca(2+) waves that do not propagate throughout the hepatic
plate. Increased gap junction coupling restored normal Ca(2+)
wave propagation when hepatocytes with low Ca(2+) signaling
ability were localized in the midlobular or the pericentral
region.Multiple spatial patterns in intracellular signaling
parameters can lead to Ca(2+) wave propagation that is
consistent with the experimentally observed spatial patterns of
Ca(2+) dynamics. Based on simulations and analysis, we predict
that increased gap junction-mediated intercellular coupling can
induce robust Ca(2+) signals in otherwise poorly responsive
hepatocytes, at least partly restoring the sinusoidally
oriented Ca (2+) waves.Our bottom-up model of agonist-evoked
spatial Ca(2+) patterns can be integrated with detailed
descriptions of liver histology to study Ca(2+) regulation at
the tissue level.
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Project description:Different focal adhesions, gap junction, adherens junction, and tight junction, TLR signaling pathway were seen when compared the HIV+ high ANA (anti-nuclear antibodies) group with low ANA group We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process.