title: CD3γ/δ in sea bass (Dicentrarchus labrax): Molecular characterization and expression analysis.
abstract: The CD3 complex is the common marker on the surface of both αβ and γδ T cells and is essential for formation of the T-cell receptor complex and for T-cell activation. In this paper, we report the gene cloning and molecular characterization of a CD3γ/δ homologue in sea bass (Dicentrarchus labrax), the analysis of transcription levels in lymphoid and non-lymphoid organs and the gene regulation after in vitro stimulation with LPS and PHA. Four cysteine residues in the extracellular domain, involved in the constitution of immunoglobulin-like domain, are present in sea bass CD3γ/δ sequence and they are conserved both in number and position from mammals to teleost sequences. Similar to other known CD3γ/δs, in sea bass CD3γ/δ there is also a conserved immunoreceptor tyrosine-based activation ITAM motif that could be responsible for its individual signal transduction capacity. The real time RT-PCR basal analysis shows the highest level of CD3γ/δ mRNA in thymus, followed by peripheral blood leucocytes, spleen, gills, gut, liver, head kidney, brain and muscle. The expression analysis under stimuli condition reveals a significant decrease of CD3γ/δ expression after LPS stimulation and a significant increase after PHA-L stimulation, in agreement with mammals results. In conclusion, these data allow us to affirm that sea bass CD3γ/δ can be used as a T cell marker and will help in adding new insight on the immune response mechanisms of sea bass.
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest systems, University of Tuscia, Largo dell'Università, 01100 Viterbo, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Randelli
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest systems, University of Tuscia, Largo dell'Università, 01100 Viterbo, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scapigliati
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest systems, University of Tuscia, Largo dell'Università, 01100 Viterbo, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Buonocore
keywords: CD3γ/δ; In vitro stimulation; Real time-PCR analysis; Sea bass; T cell responses