Pre-T Cell Receptors (Pre-TCRs) Leverage Vß Complementarity Determining Regions (CDRs) and Hydrophobic Patch in Mechanosensing Thymic Self-ligands.
J Biol Chem
; 291(49): 25292-25305, 2016 Dec 02.
Article
em En
| MEDLINE
| ID: mdl-27707880
ABSTRACT
The pre-T cell receptor (pre-TCR) is a pTα-ß heterodimer functioning in early αß T cell development. Although once thought to be ligand-autonomous, recent studies show that pre-TCRs participate in thymic repertoire formation through recognition of peptides bound to major histocompatibility molecules (pMHC). Using optical tweezers, we probe pre-TCR bonding with pMHC at the single molecule level. Like the αßTCR, the pre-TCR is a mechanosensor undergoing force-based structural transitions that dynamically enhance bond lifetimes and exploiting allosteric control regulated via the Cß FG loop region. The pre-TCR structural transitions exhibit greater reversibility than TCRαß and ordered force-bond lifetime curves. Higher piconewton force requires binding through both complementarity determining region loops and hydrophobic Vß patch apposition. This patch functions in the pre-TCR as a surrogate Vα domain, fostering ligand promiscuity to favor development of ß chains with self-reactivity but is occluded by α subunit replacement of pTα upon αßTCR formation. At the double negative 3 thymocyte stage where the pre-TCR is first expressed, pre-TCR interaction with self-pMHC ligands imparts growth and survival advantages as revealed in thymic stromal cultures, imprinting fundamental self-reactivity in the T cell repertoire. Collectively, our data imply the existence of sequential mechanosensor αßTCR repertoire tuning via the pre-TCR.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Regulação da Expressão Gênica
/
Receptores de Antígenos de Linfócitos T alfa-beta
/
Regiões Determinantes de Complementaridade
/
Timócitos
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2016
Tipo de documento:
Article