Limits...
The common cytokine receptor gamma chain and the pre-T cell receptor provide independent but critically overlapping signals in early alpha/beta T cell development.

Di Santo JP, Aifantis I, Rosmaraki E, Garcia C, Feinberg J, Fehling HJ, Fischer A, von Boehmer H, Rocha B - J. Exp. Med. (1999)

Bottom Line: Interleukin (IL)-7 interactions with its cognate receptor complex (IL-7Ralpha coupled to the common cytokine receptor gamma chain, gammac) play a dominant role in early thymopoiesis.We demonstrate that gammac-dependent cytokines do not appear to be required for normal pre-TCR function, and that the rate-limiting step in alpha/beta T cell development in gammac- mice does not involve TCR-beta chain rearrangements, but rather results from poor maintenance of early thymocytes.Thus, a series of overlapping signals derived from cytokine and T cell receptors guide the process of alpha/beta thymocyte development.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM) U429, Hôpital Necker-Enfants Malades, F-75743 Paris, France. disanto@nexker.fr

ABSTRACT
Intracellular signals emanating from cytokine and antigen receptors are integrated during the process of intrathymic development. Still, the relative contributions of cytokine receptor signaling to pre-T cell receptor (TCR) and TCR-mediated differentiation remain undefined. Interleukin (IL)-7 interactions with its cognate receptor complex (IL-7Ralpha coupled to the common cytokine receptor gamma chain, gammac) play a dominant role in early thymopoiesis. However, alpha/beta T cell development in IL-7-, IL-7Ralpha-, and gammac-deficient mice is only partially compromised, suggesting that additional pathways can rescue alpha/beta T lineage cells in these mice. We have investigated the potential interdependence of gammac- and pre-TCR-dependent pathways during intrathymic alpha/beta T cell differentiation. We demonstrate that gammac-dependent cytokines do not appear to be required for normal pre-TCR function, and that the rate-limiting step in alpha/beta T cell development in gammac- mice does not involve TCR-beta chain rearrangements, but rather results from poor maintenance of early thymocytes. Moreover, mice double mutant for both gammac and pre-Talpha show vastly reduced thymic cellularity and a complete arrest of thymocyte differentiation at the CD44(+)CD25(+) cell stage. These observations demonstrate that the pre-TCR provides the gammac-independent signal which allows alpha/beta T cell development in gammac- mice. Thus, a series of overlapping signals derived from cytokine and T cell receptors guide the process of alpha/beta thymocyte development.

Show MeSH
TCR-β rearrangements in thymus and spleen. Genomic  DNA from the indicated mice were amplified by PCR using a combination of primers specific for TCR Vβ6 and Vβ8 (sense) and a primer specific for the 3′ region of TCR Jβ2.5 (antisense). Amplification products  were detected by blot hybridization using a probe specific for the 5′ region of TCR Jβ2.5.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2192922&req=5

Figure 6: TCR-β rearrangements in thymus and spleen. Genomic DNA from the indicated mice were amplified by PCR using a combination of primers specific for TCR Vβ6 and Vβ8 (sense) and a primer specific for the 3′ region of TCR Jβ2.5 (antisense). Amplification products were detected by blot hybridization using a probe specific for the 5′ region of TCR Jβ2.5.

Mentions: Due to the severe reduction in thymocyte cell numbers in γc−/pTα−/− mice, a PCR-based strategy (31) was used to identify any TCR-β rearrangements present in these mutant thymi. DNA from control, γc−, or pTα−/− thymi contained abundant TCR-β V(D)J rearrangements, which were diverse with respect to junctional sequences present in the CDR3 region (Fig. 6; and data not shown). In contrast, rearrangements from γc−/pTα−/− mutant thymi were reduced in overall amounts, although samples derived from independent thymi contained multiple and different bands, indicating rearrangements to different Jβ segments (Fig. 6). Sequence analysis of these PCR products revealed unique Vβ CDR3 sequences, suggesting that the observed reduction in rearrangements was related to the paucity of absolute cell numbers and not to a restricted rearrangement potential (data not shown). Finally, TCR-β rearrangements were absent from the spleens of γc−/pTα−/− double mutant mice, demonstrating that the intrathymic block in α/β T cell development was complete and that no mature α/β T cells were produced that could seed the peripheral lymphoid organs (Fig. 6).


The common cytokine receptor gamma chain and the pre-T cell receptor provide independent but critically overlapping signals in early alpha/beta T cell development.

Di Santo JP, Aifantis I, Rosmaraki E, Garcia C, Feinberg J, Fehling HJ, Fischer A, von Boehmer H, Rocha B - J. Exp. Med. (1999)

TCR-β rearrangements in thymus and spleen. Genomic  DNA from the indicated mice were amplified by PCR using a combination of primers specific for TCR Vβ6 and Vβ8 (sense) and a primer specific for the 3′ region of TCR Jβ2.5 (antisense). Amplification products  were detected by blot hybridization using a probe specific for the 5′ region of TCR Jβ2.5.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2192922&req=5

Figure 6: TCR-β rearrangements in thymus and spleen. Genomic DNA from the indicated mice were amplified by PCR using a combination of primers specific for TCR Vβ6 and Vβ8 (sense) and a primer specific for the 3′ region of TCR Jβ2.5 (antisense). Amplification products were detected by blot hybridization using a probe specific for the 5′ region of TCR Jβ2.5.
Mentions: Due to the severe reduction in thymocyte cell numbers in γc−/pTα−/− mice, a PCR-based strategy (31) was used to identify any TCR-β rearrangements present in these mutant thymi. DNA from control, γc−, or pTα−/− thymi contained abundant TCR-β V(D)J rearrangements, which were diverse with respect to junctional sequences present in the CDR3 region (Fig. 6; and data not shown). In contrast, rearrangements from γc−/pTα−/− mutant thymi were reduced in overall amounts, although samples derived from independent thymi contained multiple and different bands, indicating rearrangements to different Jβ segments (Fig. 6). Sequence analysis of these PCR products revealed unique Vβ CDR3 sequences, suggesting that the observed reduction in rearrangements was related to the paucity of absolute cell numbers and not to a restricted rearrangement potential (data not shown). Finally, TCR-β rearrangements were absent from the spleens of γc−/pTα−/− double mutant mice, demonstrating that the intrathymic block in α/β T cell development was complete and that no mature α/β T cells were produced that could seed the peripheral lymphoid organs (Fig. 6).

Bottom Line: Interleukin (IL)-7 interactions with its cognate receptor complex (IL-7Ralpha coupled to the common cytokine receptor gamma chain, gammac) play a dominant role in early thymopoiesis.We demonstrate that gammac-dependent cytokines do not appear to be required for normal pre-TCR function, and that the rate-limiting step in alpha/beta T cell development in gammac- mice does not involve TCR-beta chain rearrangements, but rather results from poor maintenance of early thymocytes.Thus, a series of overlapping signals derived from cytokine and T cell receptors guide the process of alpha/beta thymocyte development.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM) U429, Hôpital Necker-Enfants Malades, F-75743 Paris, France. disanto@nexker.fr

ABSTRACT
Intracellular signals emanating from cytokine and antigen receptors are integrated during the process of intrathymic development. Still, the relative contributions of cytokine receptor signaling to pre-T cell receptor (TCR) and TCR-mediated differentiation remain undefined. Interleukin (IL)-7 interactions with its cognate receptor complex (IL-7Ralpha coupled to the common cytokine receptor gamma chain, gammac) play a dominant role in early thymopoiesis. However, alpha/beta T cell development in IL-7-, IL-7Ralpha-, and gammac-deficient mice is only partially compromised, suggesting that additional pathways can rescue alpha/beta T lineage cells in these mice. We have investigated the potential interdependence of gammac- and pre-TCR-dependent pathways during intrathymic alpha/beta T cell differentiation. We demonstrate that gammac-dependent cytokines do not appear to be required for normal pre-TCR function, and that the rate-limiting step in alpha/beta T cell development in gammac- mice does not involve TCR-beta chain rearrangements, but rather results from poor maintenance of early thymocytes. Moreover, mice double mutant for both gammac and pre-Talpha show vastly reduced thymic cellularity and a complete arrest of thymocyte differentiation at the CD44(+)CD25(+) cell stage. These observations demonstrate that the pre-TCR provides the gammac-independent signal which allows alpha/beta T cell development in gammac- mice. Thus, a series of overlapping signals derived from cytokine and T cell receptors guide the process of alpha/beta thymocyte development.

Show MeSH