Biomedical subjects

Janice C Telfer

Publications and source records attributed to Janice C Telfer.

7 recordsLinked to original sources

PubMed2006

Characterization of WC1 co-receptors on functionally distinct subpopulations of ruminant gamma delta T cells.

WC1 molecules are implicated in augmenting cellular activation as well as inducing cell cycle arrest of gammadelta T cells. Since WC1 is a large multigene family differences in outcome could result from modulation of different WC1 molecules. To further investigate this family of molecules, peripheral blood WC1(+) gammadelta T cell subpopulations were evaluated by 2-D Western blotting and RT-PCR. We found 13 cDNA intracytoplasmic tail sequences with differences in signaling motifs among them and at least 20 biochemically distinguishable WC1 spots associated with cell membranes, with some in lipid rafts. An understanding of the diversity of 2-D spots could not be resolved by evaluating T cell clones, removing sialyated carbohydrates or blotting with anti-WC1.1 or anti-WC1.2-specific antibodies. Nevertheless, while the major gammadelta T cell subpopulations in blood (WC1.1(+)/WC1.2(-) and WC1.2(+)/WC1.1(-)) both had complex 2-D patterns, virtually all spots associated with WC1.2(+)/WC1.1(-) cells bore the WC1.2 epitope, distinguishing them from the WC1.1(+) cells.

Amino Acid Sequence↗

PubMed2006

Differential TCR gene usage between WC1- and WC1+ ruminant gammadelta T cell subpopulations including those responding to bacterial antigen.

Ruminant gammadelta T cells are divided into subpopulations based on the presence or absence of WC1 co-receptors (scavenger-receptor-cysteine-rich family members uniquely expressed on gammadelta T cells). Evidence suggests WC1+ are inflammatory while WC1- are regulatory and that they also differ in their tissue distribution. Recently, this paradigm was refined further as cells that produce interferon-gamma and proliferate to autologous antigens, leptospira antigens, or IL-12 were largely found within the WC1+ subpopulation that bears the WC1.1 antigenic epitope but not that bearing the WC1.2 epitope. Here, the T cell receptor gene expression by these different subpopulations (WC1-, WC1.1+, and WC1.2+) was compared using flow cytometrically-purified cells and reverse transcriptase-polymerase chain reaction (RT-PCR). The WC1- gammadelta T cells had transcripts for all 11 possible combinations of the TRG subgroup V and C genes while those in both WC1+ subpopulations were restricted to TRGV3-TRGC5 and TRGV7-TRGC5. In contrast, all three subpopulations expressed transcripts from all four known bovine TRDV genes. Further analysis of the WC1+ gammadelta T cells that proliferated in leptospira antigen-stimulated cultures indicated that they do not represent a unique subpopulation within the larger WC1+ population based on their TCR gene usage. Moreover, sequencing of 65 transcripts showed that their junctional regions were diverse as TRGJ5-1, TRGJ5-2, TRDJ1, and TRDJ3 were used, and CDR3s ranged from 9 to 24 amino acids. The restricted but shared gammadelta TCR gene usage for WC1.1+, WC1.2+, and WC1(+)-antigen-responsive cells leaves open the possibility that the WC1 co-receptor is an important determining element in the activation process and subsequent response.

Amino Acid Sequence↗

PubMed2005

Function of ruminant gammadelta T cells is defined by WC1.1 or WC1.2 isoform expression.

WC1 is a transmembrane glycoprotein and member of the scavenger receptor cysteine rich (SRCR) family that is uniquely expressed on gammadelta T cells. The WC1 isoforms referred to as WC1.1, WC1.2, and WC1.3 are expressed on discrete subpopulations of gammadelta T cells with WC1.1 and WC1.2 expressed on mostly nonoverlapping gammadelta T cell populations. Studies have demonstrated a potential role for WC1 in modulating the response of gammadelta T cells but have not converged into a single accepted paradigm. Recent investigations that examined changing representation among mononuclear cells with age and patterns of proliferation and cytokine production by subsets bearing one or more of the previously identified variants of the WC1 molecule are summarized here. While the decrease in percentages within blood in the first year of life was found to be precipitous for WC1.1+ gammadelta T cells it was not for WC1.2+ cells. While both populations proliferated to mitogen stimulation there was a bias towards responses by WC1.2+ cells. In leptospira antigen-stimulated cultures and autologous mixed lymphocyte reaction (AMLR) cultures WC1.1+ cells proliferated and produced interferon-gamma (IFN-gamma) while WC1.2+ cells did to a much lower extent. This suggested functional differences related to the isoform of WC1 expressed. Under Th1-polarizing conditions, the WC1.1+ cells also made IFN-gamma whereas the vast majority of cells expressing WC1.2 did not. Despite the difference in IFN-gamma production, cells bearing either WC1 isoform had similar transcription levels of the high affinity IL-12 receptor subunit (IL-12Rbeta2) as well as of the transcription factors T-bet and GATA-3 when cultured with IL-12. Both populations transcribed low levels of IL-10 mRNA under Th1-polarizing conditions and TGF-beta transcripts were ubiquitously expressed by each of these cell types. Cloning and sequencing of the cytoplasmic tails of the WC1 isoforms revealed a consensus ITAM in all three isoforms but a DENY sequence adjacent to one of the SH-2 binding sites of WC1.1 only. The results suggest that WC1+ gammadelta T cells differentiated on the basis of WC1 isoform expression play distinct roles in immune responses that may be dictated by WC1 intracellular signaling.

Animals↗

PubMed2005

Gammadelta T cell function varies with the expressed WC1 coreceptor.

WC1 molecules are transmembrane glycoproteins belonging to the scavenger receptor cysteine-rich family and uniquely expressed on gammadelta T cells. Although participation of WC1+ gammadelta T cells in immune responses is well established, very little is understood regarding the significance of expressing different forms of the WC1 molecule. Two forms previously identified by mAbs, i.e., WC1.1 and WC1.2, are expressed by largely nonoverlapping subpopulations of gammadelta T cells. In this study it was shown that expression of the WC1.1 coreceptor was the main indicator of proliferation and IFN-gamma production in response to autologous and bacterial Ags as well as for IFN-gamma production without proliferation in Th1-polarizing, IL-12-containing cultures. Nevertheless, after culture in either Th1-polarizing or neutral conditions, mRNA was present for both T-bet and GATA-3 as well as for IL-12Rbeta2 in WC1.1+ and WC1.2+ subpopulations, and neither produced IL-4 under any conditions. Although the steady decrease in the proportion of WC1.1+ cells, but not WC1.2+ cells, within PBMC with animal aging suggested that the two subpopulations may have different roles in immune regulation, cells bearing either WC1.1 or WC1.2 expressed mRNA for regulatory cytokines IL-10 and TGF-beta, with TGF-beta being constitutively expressed by ex vivo cells. Overall, the results demonstrate that the form of the WC1 coreceptor expressed on gammadelta T cells divides them into functional subsets according to IFN-gamma production and proliferative capacity to specific stimuli as well as with regard to representation within PBMC. Finally, evidence is provided for minor differences in the intracytoplasmic tail sequences of WC1.1 and WC1.2 that may affect signaling.

Aging↗

PubMed2005

Inhibitors of gamma-secretase block in vivo and in vitro T helper type 1 polarization by preventing Notch upregulation of Tbx21.

Notch receptors are processed by gamma-secretase acting in synergy with T cell receptor signaling to sustain peripheral T cell activation. Activated CD4+ T cells differentiate into T helper type 1 (TH1) or TH2 subsets. Molecular cues directing TH1 differentiation include expression of the TH1-specific transcription factor T-bet, encoded by Tbx21. However, the regulation of Tbx21 remains incompletely defined. Here we report that Notch1 can directly regulate Tbx21 through complexes formed on the Tbx21 promoter. In vitro, gamma-secretase inhibitors extinguished expression of Notch, interferon-gamma and Tbx21 in TH1-polarized CD4+ cells, whereas ectopic expression of activated Notch1 restored Tbx21 transcription. In vivo, administration of gamma-secretase inhibitors substantially impeded TH1-mediated disease progression in the mouse experimental autoimmune encephalomyelitis model of multiple sclerosis. Thus, using gamma-secretase inhibitors to modulate Notch signaling may prove beneficial in treating TH1-mediated autoimmunity.

Amyloid Precursor Protein Secretases↗

PubMed2004

Evolutionary origins of lymphocytes: ensembles of T cell and B cell transcriptional regulators in a cartilaginous fish.

The evolutionary origins of lymphocytes can be traced by phylogenetic comparisons of key features. Homologs of rearranging TCR and Ig (B cell receptor) genes are present in jawed vertebrates, but have not been identified in other animal groups. In contrast, most of the transcription factors that are essential for the development of mammalian T and B lymphocytes belong to multigene families that are represented by members in the majority of the metazoans, providing a potential bridge to prevertebrate ancestral roles. This work investigates the structure and regulation of homologs of specific transcription factors known to regulate mammalian T and B cell development in a representative of the earliest diverging jawed vertebrates, the clearnose skate (Raja eglanteria). Skate orthologs of mammalian GATA-3, GATA-1, EBF-1, Pax-5, Pax-6, Runx2, and Runx3 have been characterized. GATA-3, Pax-5, Runx3, EBF-1, Spi-C, and most members of the Ikaros family are shown throughout ontogeny to be 1) coregulated with TCR or Ig expression, and 2) coexpressed with each other in combinations that for the most part correspond to known mouse T and B cell patterns, supporting conservation of function. These results indicate that multiple components of the gene regulatory networks that operate in mammalian T cell and B cell development were present in the common ancestor of the mammals and the cartilaginous fish. However, certain factors relevant to the B lineage differ in their tissue-specific expression patterns from their mouse counterparts, suggesting expanded or divergent B lineage characteristics or tissue specificity in these animals.

Amino Acid Sequence↗

PubMed2004

Localization of the domains in Runx transcription factors required for the repression of CD4 in thymocytes.

The runt family transcription factors Runx1 and Runx3 are expressed in developing murine thymocytes. We show that enforced expression of full-length Runx1 in CD4(-)CD8(-) thymocytes results in a profound suppression of immature CD4/CD8 double-positive thymocytes and mature CD4 single-positive thymocytes compared with controls. This effect arises from Runx1- or Runx3-mediated repression of CD4 expression, and is independent of positively selecting signals. Runx1 is able to repress CD4 in CD4/CD8 double-positive thymocytes, but not in mature splenic T cells. Runx-mediated CD4 repression is independent of association with the corepressors Groucho/TLE or Sin3. Two domains are required for complete Runx-mediated CD4 repression. These are contained within Runx1 aa 212-262 and 263-360. The latter region contains the nuclear matrix targeting sequence, which is highly conserved among runt family transcription factors across species. The presence of the nuclear matrix targeting sequence is required for Runx-mediated CD4 repression, suggesting that Runx transcription factors are stabilized on the CD4 silencer via association with the nuclear matrix.

Amino Acid Sequence↗