Identification of a novel cDNA, encoding a cytoskeletal associated protein, differentially expressed in diffuse large B cell lymphomas

Abstract

Diuse large B-cell lymphomas (DLBL) constitute an heterogeneous clinico-pathological entity. To characterize molecular events related to histological subtypes, clinical presentation or outcome, we compared the mRNAs expressed in a limited series of DLBL by Dierential display-reverse transcription (DDRT) and cloned a dierential cDNA, that we called LB1. LB1 open reading frame encodes a 683 amino-acid polypeptide that does not show signi®cant homology upon comparison to protein databases, nor any structural domain relating LB1 to an already known protein family. Immuno¯uorescence analysis of transfected COS cells showed a cytoplasmic ®lamentous staining, indicating that LB1 protein is tightly associated with cytoskeletal ®bers. Two LB1 transcripts, a major 3.6 ± 3.9 Kb and a minor 2.2 Kb transcripts, were detected among human haematopoietic and non-haematopoietic lines and tissues. LB1 transcripts were abundant in testis, thymus and in tumour derived cell lines, while barely detectable in liver, prostate and kidney. Concerning DLBL, LB1 expression was high in two cases of DLBL, and low or undetectable in four others, con®rming the dierential expression previously observed in the DDRT experiment. Furthermore, LB1 gene mapped to chromosome 13q14, a region that has been involved as a chromosomal breakpoint in DLBL. The cellular function of LB1 and its relationship with B cell maturation and/or oncogenesis remain to be established.

Specific primary sequence requirements for Aurora B kinase-mediated phosphorylation and subcellular localization of TMAP during mitosis

“…[21][22][23] Although its role in tumorigenesis still remains elusive, a series of recent studies indicate that TMAP plays important functions during mitosis. Expression of TMAP is regulated during the cell cycle, and the peak level of its expression is achieved at G 2 /M phases of the cell cycle.…”

Identification of a mouse cytoskeleton‐associated protein, CKAP2, with microtubule‐stabilizing properties

“…The hCKAP2 gene was originally identified as a gene highly expressed in diffuse large B cell lymphoma, and its product was subsequently reported as a cutaneous T-cell lymphoma-associated antigen. 31,32) In addition, it was shown that this gene prod-A B mCKAP2 tubulin merge mCKAP2 tubulin merge DAPI Fig. 3.…”

“…CKAP2 expression in human tumor cell lines. Because it was reported that hCKAP2 was expressed at high levels in human tumors such as hematopoietic tumors and gastric carcinomas, [31][32][33] we screened its expression in 26 human tumor cell lines by Northern blotting. hCKAP2 expression was upregulated in some tumor cell lines, although the difference in its expression levels appeared to depend on individual cell lines rather than their histologic types.…”

“…Sequencing analysis showed that this gene is the mouse homolog of the human cytoskeleton-associated protein CKAP2 gene (also termed LB1). [31][32][33] In addition, immunocytochemical staining suggested that this gene product is a microtubule-associated protein with microtubule stabilizing properties. …”

Transient phosphorylation of tumor associated microtubule associated protein (TMAP)/cytoskeleton associated protein 2 (CKAP2) at Thr-596 during early phases of mitosis

“…Tumor associated microtubule associated protein (TMAP), also known as cytoskeleton associated protein 2 (CKAP2) is frequently upregulated in various malignancies, including gastric adenocarcinoma, diffuse B-cell lymphoma and cutaneous T-cell lymphoma (Maouche-Chretien et al, 1998;Eichmuller et al, 2001;Bae et al, 2003), and also detected in various cancer cell lines (Bae et al, 2003;Jin et al, 2004). Knockdown of TMAP/CKAP2 reduces cell proliferation, whereas constitutive overexpression at a moderate level enhances proliferation of human foreskin fibroblasts (HFFs) and NIH 3T3 cells (Jeon et al, 2006), indicating that TMAP/CKAP2 is essential for normal cell growth.…”