The long-term goal of this grant is to elucidate a mechanic link responsible for aberrant responses of stem cells/progenitors or cancer initiating cells to their microenvironments. The immediate goal is to determine the physiological and pathological role of the missing in metastasis (MIM or MTSS1) gene in B lymphocytes and B-cell lymphomas. Previous studies from our lab and others have shown that MIM belongs to the family of inverse BAR-domain proteins that shapes the membrane curvature and regulates cellular polarity, endocytosis, cell motility and reorganization of the actin cytoskeleton. MIM is also frequently aberrantly expressed in various metastatic and advanced malignant cells. However, the pathological relevance of aberrant MIM expressions to malignant progression has not yet been established because of the lack of a proper animal model. We have recently found that MIM is the only I-BAR gene that is abundantly expressed in normal human and murine B lymphocytes but markedly underexpressed in a series of primary and established B lymphocytic malignant cells. We have recently established a MIM knockout mouse strain and observed that the majority of the null MIM mice developed spontaneous B-cell lymphomas within two years along with development of enlarged spleens. Preliminary study indicated several defects associated with null MIM B lineage cells: they were abnormally distributed in the bone marrow, poorly recruited to the spleen, impaired in chemotactic responses to chemokine CXCL13, deficient in the internalization of the receptor of CXCL13, and unable to polarize after stimulatio with chemokines. Furthermore, we observed that null MIM cells displayed significantly altered shapes, reduced adhesiveness to extracellular matrix and the formation of actin stress fibers. Therefore, we hypothesize that MIM plays an important role in the interaction between B lineage cells and stroma during B-cell differentiation in different lymphoid organs, and that a disturbed interaction underlies the promoting of the lymphomagenesis in MIM knockout mice. To test this hypothesis, we have planned a series of studies with three specific aims: (1) characterization of the physiological role of MIM in B lymphocytes, (2) characterization of the role of MIM deficiency in lymphomagenesis, and (3) characterization of the signaling pathway of MIM in B cells. We anticipate that accomplishment of these aims will shed light on the mechanistic link for B lineage cells to interact with their microenvironments and to progress into malignances. Because MIM represents a signaling pathway distinct from previously characterized circuits for tumorigenesis, we also expect that our study will explore new targets that may be used in cancer interventions in the future.
The proposed study will characterize a mouse strain in which the gene for missing in metastasis has been disrupted. We will use this animal model to explore the mechanism by which MIM deficiency induces tumor formation.
|Li, Lushen; Liu, Hongyu; Baxter, Shaneen S et al. (2016) The SH3 domain distinguishes the role of I-BAR proteins IRTKS and MIM in chemotactic response to serum. Biochem Biophys Res Commun 479:787-792|
|Zhan, T; Cao, C; Li, L et al. (2016) MIM regulates the trafficking of bone marrow cells via modulating surface expression of CXCR4. Leukemia 30:1327-34|
|Zeng, Xian-Chun; Luo, Xuesong; Wang, San-Xia et al. (2013) Fibronectin-mediated cell spreading requires ABBA-Rac1 signaling. J Cell Biochem 114:773-81|
|Yu, D; Zhan, X H; Zhao, X F et al. (2012) Mice deficient in MIM expression are predisposed to lymphomagenesis. Oncogene 31:3561-8|
|Cao, Meng; Zhan, Tailan; Ji, Min et al. (2012) Dimerization is necessary for MIM-mediated membrane deformation and endocytosis. Biochem J 446:469-75|
|Yu, Dan; Zhan, Xiaoguo H; Niu, Shuqiong et al. (2011) Murine missing in metastasis (MIM) mediates cell polarity and regulates the motility response to growth factors. PLoS One 6:e20845|
|Yu, Dan; Zhang, Helin; Blanpied, Thomas A et al. (2010) Cortactin is implicated in murine zygotic development. Exp Cell Res 316:848-58|
|Zheng, Datong; Niu, Shuqiong; Yu, Dan et al. (2010) Abba promotes PDGF-mediated membrane ruffling through activation of the small GTPase Rac1. Biochem Biophys Res Commun 401:527-32|
|Wang, Ying; Zhou, Kang; Zeng, Xianchun et al. (2007) Tyrosine phosphorylation of missing in metastasis protein is implicated in platelet-derived growth factor-mediated cell shape changes. J Biol Chem 282:7624-31|
|Zhu, Jianwei; Yu, Dan; Zeng, Xian-Chun et al. (2007) Receptor-mediated endocytosis involves tyrosine phosphorylation of cortactin. J Biol Chem 282:16086-94|