			Home About us Contact

Transcriptional Patterns (transcriptional + pattern)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Identification of the proteins present in the bull sperm cytosolic fraction enriched in tyrosine kinase activity: A proteomic approach

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 16 2006
Claudia Lalancette
Abstract Numerous sperm proteins have been identified on the basis of their increase in tyrosine phosphorylation during capacitation. However, the tyrosine kinases present in spermatozoa that are responsible for this phosphorylation remain unknown. As spermatozoa are devoid of transcriptional and translational activities, molecular biology approaches might not reflect the transcriptional pattern in mature spermatozoa. Working directly with the proteins present in ejaculated spermatozoa is the most reliable approach to identify the tyrosine kinases potentially involved in the capacitation-associated increase in protein tyrosine phosphorylation. A combination of tyrosine kinase assays and proteomic identification tools were used as an approach to identify sperm protein tyrosine kinases. Fractionation by nitrogen cavitation showed that the majority of tyrosine kinase activity is present in the cytosolic fraction of bovine spermatozoa. By the use of Poly-Glu:Tyr(4:1)-agarose affinity chromatography, we isolated a fraction enriched in tyrosine kinase activity. Proteomics approaches permitted the identification of tyrosine kinases from three families: Src (Lyn), Csk, and Tec (Bmx, Btk). We also identified proteins implicated in different cellular events associated with sperm capacitation and acrosome reaction. These results confirm the implication of tyrosine phosphorylation in some aspects of capacitation/acrosome reaction and reveal the identity of new players potentially involved in these processes. [source]

A dual reporter gene transgenic mouse demonstrates heterogeneity in hepatic fibrogenic cell populations

HEPATOLOGY, Issue 5 2004
Scott T. Magness
Activation of hepatic stellate cells (HSCs) and other resident mesenchymal cells into myofibroblasts expressing alpha smooth muscle actin (,SMA) and collagen I is a key event in liver fibrogenesis. However, the temporal expression profiles of ,SMA and collagen I genes in these cells is unknown. To address this question, we studied ,SMA and collagen ,1(I) transcriptional patterns in primary cultures of HSCs, and additionally, in an in vivo model of secondary biliary fibrosis using transgenic mice that express the Discomsoma sp. red fluorescent protein (RFP) and the enhanced green fluorescent protein (EGFP) reporter genes under direction of the mouse ,SMA and collagen ,1(I) promoter/enhancers, respectively. The ,SMA-RFP mice were crossed with collagen-EGFP mice to generate double transgenic mice. Reporter gene expression in cultured HSCs demonstrated that both transgenes were induced at day 3 with continued expression through day 14. Interestingly, ,SMA and collagen ,1(I) transgenes were not coexpressed in all cells. Flow cytometry analysis showed three different patterns of gene expression: ,SMA-RFP positive cells, collagen-EGFP positive cells, and cells expressing both transgenes. ,SMA-only and ,SMA/collagen expressing cells showed higher expression levels of synaptophysin, reelin, MMP13, TIMP1, and ICAM-1 compared to collagen-only expressing cells, as assessed by real-time PCR. Following bile duct ligation, ,SMA and collagen ,1(I) transgenes were differentially expressed by peribiliary, parenchymal and vascular fibrogenic cells. Peribiliary cells preferentially expressed collagen ,1(I), while parenchymal myofibroblasts expressed both ,SMA and collagen ,1(I). In conclusion, these data demonstrate heterogeneity of gene expression in myofibroblastic cells during active fibrogenesis. These reporter mice provide a useful tool to further characterize fibrogenic cell types and to evaluate antifibrotic drugs. (HEPATOLOGY 2004.) [source]

Identification of operationally tolerant liver transplant recipients,

LIVER TRANSPLANTATION, Issue S2 2010
Alberto Sánchez-Fueyo
KEY POINTS: (1) Liver allografts exhibit intrinsic tolerogenic properties that result in their spontaneous acceptance in many experimental animal models. (2) In clinical transplantation, liver allografts require milder immunosuppression (IS) regimens than other organs, are remarkably resistant to antibody-mediated rejection, and only very rarely are lost because of immunological insults. (3) A fraction of stable liver transplant recipients can withdraw from all IS therapy and then maintain normal graft function and not experience rejection. This phenomenon is known as spontaneous operational tolerance. (4) The intentional discontinuation of IS in stable liver transplant recipients has led to successful weaning in almost 20% of recipients, but the true prevalence of spontaneous operational tolerance in unselected recipients is still unknown. (5) The prevalence could be higher in pediatric recipients undergoing transplantation before 1 year of age and in adult recipients with more than 10 years of posttransplant follow-up. (6) Rejection occurring during medically supervised IS weaning trials tends to be mild and, in the overwhelming majority of cases, can be easily resolved without the administration of high-dose IS. (7) Tolerant liver recipients exhibit specific transcriptional patterns in peripheral blood and in liver tissue that may constitute future diagnostic markers of tolerance. (8) There is still no formal proof that the discontinuation of low-dose IS in long-term surviving liver recipients improves the morbidity and mortality rates associated with IS therapy. Liver Transpl 16:S82-S86, 2010. © 2010 AASLD. [source]

Expression and chromosomal organization of mouse meiotic genes

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2010
Hiba Waldman Ben-Asher
Microarray technology which enables large scale analysis of gene expression and thus comparison between transcriptomes of different cell types, cells undergoing different treatments or cells at different developmental stages has also been used to study the transcriptome involved with spermatogenesis. Many new germ cell-specific genes were determined, and the resulting genes were classified according to different criteria. However, the biological significance of these classifications and their clustering according to developmental transcriptional patterns during spermatogenesis have not yet been addressed. In this study we utilized mouse testicular transcriptome analysis at five distinct post-natal ages (Days 7, 10, 12, 14, and 17), representing distinct meiotic stages, in an attempt to better understand the biological significance of genes clustered into similar expression patterns during this process. Among 790 sequences that showed an expression level change of twofold or more in any of the five key stages that were monitored, relative to the geometric average of all stages, about 40% peaked and about 30% were specifically suppressed at post-natal day 14 (representing the early pachytene stage of spermatocytes), reflecting tight transcriptional regulation at this stage. We also found that each of the six main transcription clusters that were determined was characterized by statistically significant representation of genes related to specific biological processes. Finally, our results indicated that genes important for meiosis are not randomly distributed along the mouse genome but rather preferentially located on specific chromosomes, suggesting for the first time that chromosomal location might be a regulating factor of meiotic gene expression. Mol. Reprod. Dev. 77: 241,248, 2010. © 2009 Wiley-Liss, Inc. [source]