Cloning of a Second Dendritic Cell-associated C-type Lectin (Dectin-2) and Its Alternatively Spliced Isoforms

Abstract

Using a subtractive cDNA cloning strategy, we isolated previously five novel genes that were expressed abundantly by the murine dendritic cell (DC) line XS52, but not by the J774 macrophage line. One of these genes encoded a unique, DC-associated C-type lectin, termed "dectin-1." Here we report the characterization of a second novel gene that was also expressed in a DC-specific manner. Clone 1B12 encoded a type II membrane-integrated polypeptide of 209 amino acids containing a single carbohydrate recognition domain motif in the COOH terminus. The expression pattern of this molecule, termed "dectin-2," was almost indistinguishable from that for dectin-1; that is, both were expressed abundantly at mRNA and protein levels by the XS52 DC line, but not by non-DC lines, and both were detected in spleen and thymus, as well as in skin resident DC (i.e. Langerhans cells). Interestingly, reverse transcriptasepolymerase chain reaction and immunoblotting revealed multiple bands of dectin-2 transcripts and proteins suggesting molecular heterogeneity. In fact, we isolated additional cDNA clones encoding two distinct, truncated dectin-2 isoforms. Genomic analyses indicated that a full-length dectin-2 (␣ isoform) is encoded by 6 exons, whereas truncated isoforms (␤ and ␥) are produced by alternative splicing. We propose that dectin-2 and its isoforms, together with dectin-1, represent a unique subfamily of DC-associated C-type lectins. Dendritic cells (DC)1 are far more potent than other antigenpresenting cells (e.g. macrophages and B cells) in their capacity to activate immunologically naive T cells, and DC are, indeed, responsible for initiating T cell-mediated immune responses to a variety of antigens (1, 2). Members of the DC family are distributed to virtually all the organs (except the brain), where they serve as tissue resident antigen-presenting cells, playing critical roles in presenting environmental, microbial, and tumor-associated antigens to the immune system.Several years ago, we developed stable DC lines from the mouse epidermis (3). These lines, termed as the XS series, maintain many important features of skin resident DC, i.e. Langerhans cells, and they have provided a useful tool for the application of modern technologies for studying DC biology (3-13). Most recently, we employed the subtractive cDNA cloning strategy to identify genes that were expressed preferentially by DC. 2 Briefly, we constructed a DC-specific cDNA library by subtracting cDNAs prepared from the XS52 DC line with excess amounts of mRNAs isolated from the J774 macrophage line. Following three rounds of screening of this library, we identified five novel genes that were expressed selectively by XS52 DC, but not by J774 macrophages. One of these genes encoded a type II membrane-associated polypeptide of 244 amino acids (aa) containing a single carbohydrate recognition domain (CRD) motif at the COOH-terminal end. This polypeptide was, therefore, designated as DC-associated C-type (Ca 2ϩ -dependent) lectin-1 or dectin-1. Dectin-1 mRNA was expre...

Identification of a Novel, Dendritic Cell-associated Molecule, Dectin-1, by Subtractive cDNA Cloning

“…In sum, dectin-1 is the sixth member of the unique family of DC-associated C-type lectins. Very recently, we have identified the seventh member, termed "dectin-2," which resembles dectin-1 by virtue of the molecular configuration (a type II membrane-integrated polypeptide with a single CRD in the extracellular domain) and the expression profile (preferential expression by DC in both lymphoid and nonlymphoid tissues) (75).…”

The role of pattern recognition receptors in the innate recognition ofCandida albicans

“…109 Dectin-2 is another PRR for phagocytic cells to recognize C. albicans mannans. [110][111][112] By using mouse leukemic monocyte macrophage cell line RAW 264.7, Dectin-2 is found mainly involved in the recognition of C. albicans hyphae and induce intracellular signals through FcgR. 49 A recent study revealed that Dectin-3 recognized a-mannans on the surfaces of C. albicans hyphae and induced NF-kB activation in bone marrow-derived macrophages from C57B/L6 mice.…”

Dectin-2 is predominantly myeloid restricted and exhibits unique activation-dependent expression on maturing inflammatory monocytes elicitedin vivo

“…DC-associated C-type lectin-2 (Dectin-2/Clecsf10) is a type II membrane receptor from the NK gene cluster [1][2][3]. It has a short cytoplasmic tail, with no obvious signalling motifs, and a C-terminal C-type lectin domain on the end of a short 'stalk' region [1,2].…”

“…It has a short cytoplasmic tail, with no obvious signalling motifs, and a C-terminal C-type lectin domain on the end of a short 'stalk' region [1,2]. Although Dectin-2, like other C-type lectins, contains conserved motifs for the Ca 2+ -dependent recognition of mannose, reports of a lectin activity of Dectin-2 have been contradictory [1,2]. Formerly reported as NKCL, Dectin-2 was discovered as an over-expressed transcript in the spleen during an experimental murine model of acute myeloid leukaemia [1].…”