LIFE09200604002 Lalit Sehgal - Homi Bhabha National Institute

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