Alternatively Spliced CD44 Isoforms Containing Exon v10 Promote Cellular Adhesion through the Recognition of Chondroitin Sulfate-Modified CD44

Chiu, Roland K.; Droll, Armin; Dougherty, Shona T.; Carpenito, Carmine; Cooper, David L.; Dougherty, Graeme J.

doi:10.1006/excr.1999.4391

Cited by 18 publications

(16 citation statements)

References 33 publications

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“…In this and previous studies we have shown that CD44H, CD44R1 (v8 -10-containing), and CD44R2 (v10-containing) are all equivalent in their HA-binding function when expressed in either TIL1 cells or COS7 cells (5,6). However, unlike CD44H, the exon v8 -10-containing isoform CD44R1 was capable of promoting cell-cell adhesion (6,15). Because CD44R2 has a similar activity, it was concluded that this unique function was conferred by the presence of sequences encoded by exon v10 (6).…”

Section: Discussionsupporting

confidence: 55%

“…However, this finding has not been borne out in all studies (5,21,22) and can perhaps be best explained by cellspecific differences in the post-translational modification of the two CD44 isoforms (23,24). In this and previous studies we have shown that CD44H, CD44R1 (v8 -10-containing), and CD44R2 (v10-containing) are all equivalent in their HA-binding function when expressed in either TIL1 cells or COS7 cells (5,6). However, unlike CD44H, the exon v8 -10-containing isoform CD44R1 was capable of promoting cell-cell adhesion (6,15).…”

Section: Discussionmentioning

confidence: 69%

“…Thus, although CD44H and the exon v10-containing CD44 isoforms CD44R1 and CD44R2 appear equivalent in their ability to bind the glycosaminoglycan hyaluronan (HA) 1 (5), only exon v10-containing CD44 isoforms possess the unique ability to directly bind to one another when expressed on the cell surface (5). The novel adhesive phenotype conferred by the inclusion of sequences encoded by exon v10 appeared not to be dependent upon the presence of HA but instead involved the recognition of chondroitin sulfate (CS) moieties presented in association with other CD44 molecules (6). This finding is in agreement with previous studies showing that CD44 can bind a variety of CS-modified protein ligands, including serglycin (7), the invariant chain of major histocompatibility complex/HLA class II (8), aggrecan (9), and versican (10).…”

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confidence: 99%

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Identification of Sequence Motifs Responsible for the Adhesive Interaction between Exon v10-containing CD44 Isoforms

Hayes¹,

Chiu²,

Carpenito³

et al. 2002

Journal of Biological Chemistry

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Previous studies have demonstrated that CD44 isoforms containing the alternatively spliced exon v10 promote cell-cell adhesion via a mechanism that involves the recognition of chondroitin sulfate side chains presented on the surface of interacting cells in association with other CD44 molecules. Sequence analysis revealed the presence within exon v10 of two motifs that may be relevant to this interaction, a B[X 7 ]B motif that may contribute to the recognition and binding of chondroitin sulfate and a serine-glycine motif that may serve as a site of chondroitin sulfate attachment. To determine whether either of these two motifs explain the unique adhesive activity of exon v10-containing CD44 isoforms, each was targeted by site-directed mutagenesis, and the adhesive activity of the resultant mutants was determined using a quantitative cell-cell binding assay. The data obtained demonstrate conclusively that it is the exon v10-encoded B[X 7 ]B motif that is solely responsible for the enhanced adhesive activity of exon v10-containing CD44 isoforms.Numerous studies have documented a striking correlation between the presence of certain alternatively spliced isoforms of the adhesion protein CD44 on the surface of tumor cells and both metastatic propensity and poor prognosis (1). For example, in the case of colorectal carcinoma, patients with Duke's C and D tumors that express high levels of CD44R1, a CD44 isoform that contains sequences encoded by the alternatively spliced exons v8, v9, and v10, exhibit a far worse 5-year disease-free survival rate than equivalent patients with tumors that express predominantly CD44H, an isoform that lacks these differentially utilized exons (2, 3). Similar findings have been reported for a wide range of other hemopoietic and nonhemopoietic malignancies (1, 4). Recent studies from our group and others have provided insights into the molecular mechanisms that underlie this important relationship. Thus, although CD44H and the exon v10-containing CD44 isoforms CD44R1 and CD44R2 appear equivalent in their ability to bind the glycosaminoglycan hyaluronan (HA) 1 (5), only exon v10-containing CD44 isoforms possess the unique ability to directly bind to one another when expressed on the cell surface (5). The novel adhesive phenotype conferred by the inclusion of sequences encoded by exon v10 appeared not to be dependent upon the presence of HA but instead involved the recognition of chondroitin sulfate (CS) moieties presented in association with other CD44 molecules (6). This finding is in agreement with previous studies showing that CD44 can bind a variety of CS-modified protein ligands, including serglycin (7), the invariant chain of major histocompatibility complex/HLA class II (8), aggrecan (9), and versican (10). The precise molecular nature of the CS-dependent interaction that occurs between exon v10-containing CD44 isoforms remains to be determined. Exon v10 encodes an additional B [X 7 ]B motif that in CD44 and other proteins has been shown to play a pivotal role in mediating the bindin...

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Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 69%

mentioning

confidence: 99%

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Identification of Sequence Motifs Responsible for the Adhesive Interaction between Exon v10-containing CD44 Isoforms

Hayes¹,

Chiu²,

Carpenito³

et al. 2002

Journal of Biological Chemistry

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“…CD44v molecules can also bind to matrix components such as fibronectin and collagen, [30][31][32] possibly mediated by chondroitin sulphate moieties associated with CD44 isoforms containing exon v10. 58,59 Binding of XG-1 plasma cells to in vitro synthesized ECM derived from bone marrow adherent cells, however, depended largely on VLA-4 -fibronectin and CD44s -HA interaction. CD44v-specific antibodies used in this study did not interfere with ECM binding.…”

Section: Figurementioning

confidence: 99%

CD44 variant isoforms are involved in plasma cell adhesion to bone marrow stromal cells

Driel

Günthert²,

Kessel³

et al. 2002

Leukemia

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Expression of CD44v9-containing isoforms (CD44v9) on myeloma plasma cells correlates with unfavorable prognosis, suggesting that CD44 variant molecules are involved in the disease process. In this study, the presence of CD44v on B cell lines from different stages of development was analyzed by flow cytometry and a role in adhesion to stromal cells from different tissues was evaluated in in vitro binding assays. CD44v3, v6 and v9 isoforms were exclusively expressed on plasma cell lines and CD44v9 expression correlated with IL-6-dependent plasma cell growth. Binding studies using CD44 isoformspecific reagents showed that CD44v6 and CD44v9 were involved in binding to bone marrow stromal cells, but not to in vitro synthesized ECM or hyaluronic acid. CD44v9-mediated plasma cell binding resulted in a significant induction of IL-6 secretion by bone marrow stromal cells. Large differences in quantitative plasma cell binding to stromal cells from different tissues were observed. These, however, could not be related to a differential use of CD44v in these binding processes. The role of CD44v9 in adhesion induced IL-6 secretion and its preferential expression on IL-6-dependent plasma cell lines may explain the previously observed correlation between CD44v9 expression and adverse prognosis in multiple myeloma.

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“…7,8,10 While the precise molecular mechanisms that underlie this relationship remain to be fully defined, studies from our group have shown that unlike CD44 H, CD44R1 can promote cell-cell adhesion via the recognition of chondroitin sulfate side chains, particularly if these are presented on the surface of opposing cells in association with other CD44R1 molecules. 11 Recently, we have extended these studies and demonstrated that differential alternative splicing of CD44 can also be exploited in the context of tumor-targeted gene therapy. 4 Specifically, we have developed a series of ''splice-activated gene expression'' (pSAGE) vectors that contain minigene constructs in which a putative therapeutic gene is linked to two or more CD44 exons along with their corresponding introns such that expression of a chimeric protein incorporating the gene of interest can only occur if the intronic sequences are completely and accurately removed from the transcript that is produced.…”

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confidence: 97%

Molecular mechanisms regulating the tumor-targeting potential of splice-activated gene expression

Hayes

Dougherty

Davis³

et al. 2004

Cancer Gene Ther

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Previous studies have suggested that differences in the ability of normal and malignant cells to process certain alternatively spliced pre-mRNA transcripts can be exploited as a potentially powerful means of targeting the expression of therapeutic genes to tumor cells in vivo and in vitro. Specifically, it was shown that efficient processing of minigene constructs containing the alternatively spliced CD44 exons v9 and v10 only occurs in tumor cells that express CD44 isoforms that incorporate these exons (e.g. CD44R1). In the present study, efforts were made to define the molecular mechanisms that underlie the apparent specificity of this process. RT-PCR analysis and DNA sequencing were used to characterize the various splicing events that occur between CD44 exons v8, v9 and v10 following transfection of minigene constructs containing these various exons into CD44R1-positive (PC3) and CD44R1-negative (T24) cell lines. The results obtained confirm that although the v8-v9 intron is efficiently removed in both CD44R1-positive and CD44R1-negative cells, the corresponding v9-v10 intron is accurately spliced and the exons appropriately joined only in lines that express v10-containing CD44 isoforms (e.g. PC3). In CD44R1-negative cell lines (e.g. T24) alternative 5 0 and 3 0 splice sites located within the v9-v10 intron are preferentially used, resulting in various portions of the intron being retained within the final processed mRNA product. It is proposed that identification of these functionally important intronic sequence elements will facilitate the development of second generation ''splice activated gene expression'' vectors that may prove useful in various cancer gene therapy applications.

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Alternatively Spliced CD44 Isoforms Containing Exon v10 Promote Cellular Adhesion through the Recognition of Chondroitin Sulfate-Modified CD44

Cited by 18 publications

References 33 publications

Identification of Sequence Motifs Responsible for the Adhesive Interaction between Exon v10-containing CD44 Isoforms

Identification of Sequence Motifs Responsible for the Adhesive Interaction between Exon v10-containing CD44 Isoforms

CD44 variant isoforms are involved in plasma cell adhesion to bone marrow stromal cells

Molecular mechanisms regulating the tumor-targeting potential of splice-activated gene expression

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