HCAR and MCAR: The human and mouse cellular receptors for subgroup C adenoviruses and group B coxsackieviruses

Abstract

The subgroup C of the adenoviruses (Ad) and the group B coxsackieviruses (CVB) are structurally unrelated viruses that are known to compete for an unidentified cell surface receptor. We now describe the isolation of cDNAs from human and mouse that encode the human CVB and Ad2 and 5 receptor (HCAR) and the mouse CVB Ad2 and 5 receptor (MCAR). Both are 46-kDa glycoproteins whose primary amino acid sequences are highly homologous. Structurally, HCAR and MCAR appear to be transmembrane proteins that contain two extracellular immunoglobulin-like domains and therefore belong to this superfamily. Transfection of either of these cDNA molecules into receptor-negative NIH 3T3 cells conferred susceptibility to CVB infection and permitted the expression of ␤-galactosidase from a recombinant Ad5 vector. In addition, HCAR and MCAR mRNAs could be detected on Northern blots of oligo(dT)-selected RNA from receptor-positive HeLa cells and TCMK-1 as well as several tissues of human and mouse origin that are known to be targets for Ad and CVB infections. Finally, Western blots using antibodies that inhibit virus binding to either the human or mouse CVB receptors detected 46-kDa proteins in HCARand MCAR-transfected cells, respectively. Taken together, these results confirm that the isolated cDNAs encode the receptors for the subgroup C Ad and CVB.The ability of animal viruses to infect host cells is dependent on the presence of an appropriate cellular receptor. In general, viruses of different families do not compete for binding to a common receptor. However, adenovirus (Ad) serotypes 2 (Ad2) and 5 (Ad5) and the parental group B coxsackieviruses (CVB) are human pathogens that obviously share a common receptor although they belong to divergent virus families (1). The Ad are DNA viruses that contain fiber proteins protruding from the 5-fold vertices of an icosahedral capsid. It is the terminal portion of the fiber known as the ''knob'' that is responsible for receptor binding (2). In contrast, the CVB are RNA viruses that lack fiber structures and are presumed to attach to cells through insertion of the receptor into a ''canyon'' on the surface of the virus (3). Interestingly, although these viruses use a common receptor they do not exhibit a similar host range (4). The CVB are known to infect a variety of organs, including the brain, intestines, heart, pancreas, and lungs, whereas the Ad primarily infect the intestines and lungs (4, 5). Therefore, these differences must be due to restrictions within the Ad life cycle subsequent to receptor attachment. We demonstrate here that transfection of either HCAR or MCAR cDNA into receptor-negative NIH 3T3 cells is sufficient to confer susceptibility to subgroup C Ad and CVB infection. MATERIALS AND METHODScDNA Library Screening. Five micrograms of twice oligo-(dT)-selected TCMK-1 RNA was used to construct a cDNA library in the ZAP Express vector using the ZAP Express cDNA synthesis kit (Stratagene). A library of 4 ϫ 10 5 primary clones was amplified once in the XL1-Blue MRFЈ strain of...

Imaging and tissue biodistribution of 99mTc-labeled adenovirus knob (serotype 5)

“…injection in mice, the 99m Tc-Ad5K rapidly localized to the liver in a dose-dependent manner, with specific binding also found in the heart, kidney and lungs. The binding of 99m Tc-Ad5K in these four tissues is consistent with the report of Tomko et al 14 that found expression of the Ad5K receptor in these same tissues. Furthermore, the lack of binding of 99m Tc-Ad5K in skeletal muscle is also consistent with the lack of the Ad5K receptor in this tissue.…”

“…Furthermore, the lack of binding of 99m Tc-Ad5K in skeletal muscle is also consistent with the lack of the Ad5K receptor in this tissue. 14 Excess anti-Ad5K antibody slowed the liver uptake of 99m Tc-Ad5K. The liver localization was more completely blocked with excess Ad5K, but not with Ad3K.…”

“…[11][12][13] Two receptors for Ad5 have been identified. 14,15 Following attachment, the next step in infection by Ad2 and Ad5 is internalization of the virion by receptor-mediated endocytosis, a process involving the lower affinity of Arg-Gly-Asp (RGD) peptide sequences in the penton base to secondary host cell receptors, integrins ␣ v ␤ 3 and ␣ v ␤ 5 . 16,17 Thus, the major determinant of Ad tropism is the initial high-affinity interaction between the knob domain of the fiber protein and its cognate cellular receptor.…”

CAR is a cell–cell adhesion protein in human cancer cells and is expressionally modulated by dexamethasone, TNFα, and TGFβ

“…[1][2][3] For gene therapy of human cancer cells, CAR has become of interest both due to its crucial function in adenoviral gene transfer and its potential role in cancer progression. 4,5 Little is known about the physiological cellular function and regulatory mechanism of CAR expression in cancer cells or in normal tissues.…”

Dual targeting of gene delivery by genetic modification of adenovirus serotype 5 fibers and cell-selective transcriptional control

“…This is particularly important for cell types that have low or negligible coxsackie and adenovirus receptor (CAR) or heparan sulfate proteoglycans (HSPG) expression, the primary receptors for Ad 5 and AAV-2, respectively. [10][11][12] It is important to note, however, that vectors modified in this manner are not selective and can transduce a wide repertoire of cell types. In fact, RGD-modified vectors were originally developed to broaden the tropism of Adbased vectors.…”