Signal regulatory protein molecules are differentially expressed by CD8- dendritic cells.
A normalized subtracted gene expression library was generated from freshly isolated mouse dendritic cells (DC) of all subtypes, then used to construct cDNA microarrays. The gene expression profiles of the three splenic conventional DC (cDC) subsets were compared by microarray hybridization and two genes encoding signal regulatory protein beta (Sirpbeta1 and Sirpbeta4) molecules were identified as differentially expressed in CD8(-) cDC. Genomic sequence analysis revealed a third Sirpbeta member localized in the same gene cluster. These Sirpbeta genes encode cell surface molecules containing extracellular Ig domains and short intracytoplasmic domains that have a charged amino acid in the transmembrane region which can potentially interact with ITAM-bearing molecules to mediate signaling. Indeed, we demonstrated interactions between Sirpbeta1 and beta2 with the ITAM-bearing signaling molecule Dap12. Real-time PCR analysis showed that all three Sirpbeta genes were expressed by CD8(-) cDC, but not by CD8(+) cDC or plasmacytoid pre-DC. The related Sirpalpha gene showed a similar expression profile on cDC subtypes but was also expressed by plasmacytoid pre-DC. The differential expression of Sirpalpha and Sirpbeta1 molecules on DC was confirmed by staining with mAbs, including a new mAb recognizing Sirpbeta1. Cross-linking of Sirpbeta1 on DC resulted in a reduction in phagocytosis of Leishmania major parasites, but did not affect phagocytosis of latex beads, perhaps indicating that the regulation of phagocytosis by Sirpbeta1 is a ligand-dependent interaction. Thus, we postulate that the differential expression of these molecules may confer the ability to regulate the phagocytosis of particular ligands to CD8(-) cDC.
Lahoud
Mireille H
MH
Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia. lahoud@wehi.edu.au
Proietto
Anna I
AI
Gartlan
Kate H
KH
Kitsoulis
Susie
S
Curtis
Joan
J
Wettenhall
James
J
Sofi
Mariam
M
Daunt
Carmel
C
O'keeffe
Meredith
M
Caminschi
Irina
I
Satterley
Keith
K
Rizzitelli
Alexandra
A
Schnorrer
Petra
P
Hinohara
Atsushi
A
Yamaguchi
Yasunori
Y
Wu
Li
L
Smyth
Gordon
G
Handman
Emanuela
E
Shortman
Ken
K
Wright
Mark D
MD
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016827:CD8 Antigens / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology; D015723:Gene Library; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics*; D015398:Signal Transduction / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000378:metabolism
D016827:CD8 Antigens; D011956:Receptors, Cell Surface; C501921:SIRPB1 protein, human