Requirement ofN-Myristoyltransferase 1 in the Development of Monocytic Lineage

Abstract

N-myristoyltransferase (NMT) exists in two isoforms, NMT1 and NMT2, that catalyze myristoylation of various proteins crucial in signal transduction, cellular transformation, and oncogenesis. We have recently demonstrated that NMT1 is essential for the early development of mouse embryo. In this report, we have demonstrated that an invariant consequence of NMT1 knock out is defective myelopoesis. Suppressed macrophage colony forming units were observed in M-CSF-stimulated bone marrow cells from heterozygous (+/–) Nmt1-deficient mice. Homozygous (−/−) Nmt1-deficient mouse embryonic stem cells resulted in drastic reduction of macrophages when stimulated to differentiate by M-CSF. Furthermore, to understand the requirement of NMT1 in the monocytic differentiation we investigated the role of NMT, pp60c−Src (NMT substrate) and heat shock cognate protein 70 (inhibitor of NMT), during PMA-induced differentiation of U937 cells. Src kinase activity and protein expression increased during the differentiation process along with regulation of NMT activity by hsc70. NMT1 knock down in PMA treated U937 cells showed defective monocytic differentiation. We report in this study novel observation that regulated total NMT activity and NMT1 is essential for proper monocytic differentiation of the mouse bone marrow cells.

Monoclonal antibody to novel cell surface epitope on Hsc70 promotes morphogenesis of bile ducts in newborn rat liver

“…It is also plausible that Hsc70 is required for recycling of surface proteins and targets them for proteosomal degradation. Hsc70 has also been implicated in various differentiation and developmental processes (de la Rosa et al 1998;Elefant and Palter 1999;Vega-Nunez et al 1999;Shrivastav et al 2008), a finding consistent with its involvement as an active component of survival and proliferation pathways. As reported here, studies initially designed to label OC.10 expressing cells in situ for cell isolation schemes for lineage analysis demonstrated that binding of MAb OC.10 administered by intrasplenic injection promoted a change in bile duct morphology.…”

N-myristoyltransferase in the leukocytic development processes

“…4a, b, respectively). Additionally, the total number of BMDM obtained from heterozygous (+/−) Nmt1-deficient mouse are almost one-fourth those of BMDM WT (Shrivastav et al 2008). Furthermore, more abundant cytoplasm with cytoplasmic projections and the presence of few cytoplasmic granules are observed in BMDM WT, whereas BMDM from heterozygous (+/−) Nmt1-deficient mice lack these features (Fig.…”

“…4e). The results indicate a partially diminished ability of the myeloid lineage in Nmt1 (+/−) mice to differentiate (Shrivastav et al 2008). When embryonic stem (ES) cells isolated from WT and homozygous (−/−) Nmt1-deficient mice are cultured on a feeder-independent system in the presence of M-CSF, and when the macrophage population is determined by the expression of the F4/80 surface marker by flow cytometry, the expression of AlexaFluor-488-conjugated F4/80 is observed in 1.4% of the homozygous (−/−) Nmt1-deficient ES cells as compared with 17.0% of the WT ES cells (Fig.…”

“…The BMC taken from wild-type (WT) and heterozygous (+/−) Nmt1-deficient mice and cultured in the presence of mouse macrophage colony-stimulating factor (mMCSF) for differentiation into monocytes/macrophages do not develop in a similar fashion (Shrivastav et al 2008). The Wright-Giemsa-stained bone-marrow-derived macrophages (BMDM) from WT mice (BMDM WT) are markedly different from those of heterozygous (+/−) Nmt1-deficient mice (Fig.…”

“…4a, b, respectively). The colony-forming ability of the bone marrow from WT and heterozygous (+/−) Nmt1-deficient mice have been studied in order to understand the role of NMT1 in myelopoesis (Shrivastav et al 2008). When the BMC obtained from WT and heterozygous (+/−) Nmt1-deficient mice are cultured in the presence or absence of GM-CSF (Fig.…”