LIFE09200604002 Lalit Sehgal - Homi Bhabha National Institute
LIFE09200604002 Lalit Sehgal - Homi Bhabha National Institute
LIFE09200604002 Lalit Sehgal - Homi Bhabha National Institute
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loss of 14-3-3ε the T cell activation is more as determined by the increased<br />
phosphorylation of phospolipaseCγ at Tyrosine 783 (Figure 4.4.12). Therefore, these<br />
results suggest that 14-3-3ε may negatively regulate T cell activation.<br />
Bone marrow cells from 14-3-3ε knockdown mice were not capable of inducing<br />
splenomegaly in immunocompromised mice suggesting that the defects in lymphoid<br />
behaviour that are observed in the 14-3-3ε knockdown mice are not due to systemic<br />
defects caused by the knockdown of 14-3-3ε in hematopoietic system (Figure 4.4.13).<br />
Splenomegaly is often seen in leukemia; however isolated splenocytes from 14-3-3ε<br />
knockdown mice did not form a tumor when injected subcutaneously into<br />
immunocompromised mice. However, it was observed that the enlarged lymph nodes<br />
present in some of the 14-3-3ε knockdown mice, developed tumors when transplanted<br />
subcutaneously in SCID mice and the tumor was transplantable for 3 successive<br />
transplantations, thereby suggesting that enlarged lymph node from 14-3-3ε knockdown<br />
mice can form tumors (Figure 4.4.14). Interestingly, multiple reports have suggested that<br />
14-3-3ε levels are reduced in adult T-cell leukemias (8, 9). Our results suggest that loss of<br />
14-3-3ε results in increased division and survival of immature thymocytes, however<br />
additional hits maybe required for these cells to give rise to neoplastic disease. These<br />
results are consistent with the observation that the NIH 3T3 derived 14-3-3ε knockdown<br />
cells which do not have an intact p53 pathway (176) are transformed (Figure 4.4.16).<br />
These results suggest that loss of 14-3-3ε could result in neoplastic transformation.<br />
It has been reported previously mice heterozygous with respect to 14-3-3ε are normal and<br />
fertile, however homozygous null mice died at birth due to defects in the organization of<br />
cortical layers resulting in lower neuronal migration of hippocampal and cortical neurons<br />
(363). We have not observed any 14-3-3ε knockdown mice that died at birth, possibly<br />
because the 14-3-3ε protein levels in these mice are sufficient to support normal cortical<br />
development, which is compromised in the knockout mice (363). We found that the<br />
thickness for cortical layer in knockdown mice is reduced in some of the 14-3-3ε<br />
knockdown mice generated as determined by in-situ hybridization using cortical layer II-<br />
IV specific marker cux2 (Figure 4.4.3). These results are consistent with the observations<br />
that are made in 14-3-3ε knockout mice. However, the differences between WT and 14-3-<br />
3ε knockdown mice are difficult to quantify and need to be repeated with larger numbers<br />
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