(A) cDNA was generated from hTERT-HUVEC stably expressing the EV or FLAG-tagged vIL-6 and used for qPCR analysis of the total CEACAM1 concept. 1 (CEACAM1) at the protein and concept levels. CEACAM1 has been implicated in tumor invasion and metastasis and promotes migration and vascular remodeling in endothelial cells. We report that vIL-6 upregulates CEACAM1 by a STAT3-dependent mechanism and that CEACAM1 promotes vIL-6-mediated migration. Furthermore, latent andde novoKSHV infections of endothelial cells also induce CEACAM1 expression. Collectively, our data suggest that vIL-6 modulates endothelial cell migration by upregulating the expression of cellular factors, including CEACAM1. == IMPORTANCE == Kaposis sarcoma-associated herpesvirus (KSHV) is linked with the development of three MUT056399 human malignancies, Kaposis sarcoma, multicentric Castlemans disease, and primary effusion lymphoma. KSHV expresses many factors that enable the computer virus to manipulate the host environment in order to persist and induce disease. The viral interleukin-6 (vIL-6) produced by KSHV is structurally and functionally homologous to the human cytokine interleukin-6, except that vIL-6 is secreted slowly and functions primarily from inside the sponsor cell. To investigate the unique intracellular role of vIL-6, we analyzed the impact of vIL-6 on endothelial cell gene expression. We report that vIL-6 significantly alters the expression of genes associated with cell movement, including that intended for CEACAM1. The gene intended for CEACAM1 was upregulated by vIL-6 and by latent and primary KSHV infection and promotes vIL-6-mediated endothelial cell migration. This work advances the fields understanding of vIL-6 function and its contribution to KSHV pathogenesis. == INTRODUCTION == Kaposis sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8, is the eighth human herpesvirus identified and is the etiological agent of Kaposi’s sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castlemans disease (MCD) (13). KSHV-associated malignancies typically, but not always, present in immunosuppressed patients such as HIV-positive individuals, and because of the high AIDS incidence Rabbit Polyclonal to COPZ1 in sub-Saharan Africa, KS has become the most common cancer among African men (4, 5). KSHV is a gammaherpesvirus that has a double-stranded DNA genome and enveloped virion (6) and is able to transition between a latent phase and an actively replicating lytic phase. The virus expresses > 80 open reading frames (ORFs), many of which inhibit various host immune defenses or promote the growth and transformation of sponsor cells. These strategies allow KSHV to persist intended for the life of the host and induce pathogenesis in immunocompromised individuals. The KSHV protein expressed by ORF K2 is known as viral interleukin-6 (vIL-6) because of its sequence and structural similarity to the cytokine, human interleukin-6 (hIL-6) (79). vIL-6 is expressed at low but functional levels during viral latency and becomes highly upregulated during lytic induction (1012). Importantly, vIL-6 can be detected in the serum and/or tissue of patients with KSHV-associated malignancies, and in those with MCD, higher vIL-6 levels correlate with a poorer prognosis (1315). vIL-6 expression is transforming in NIH 3T3 cells (16), and a transgenic mouse expressing vIL-6 developed MCD-like disease (17). vIL-6 has been shown to drive the expression of vascular endothelial growth factor (VEGF) and induce hematopoiesis and angiogenesis (16). Additionally , vIL-6 hard disks the expression of hIL-6 (16, 18) and promotes cell migration and survival, as well as activation of hIL-6-dependent signaling cascades such as the JAK/STAT, mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3K) pathways (1923). Despite their structural similarities, vIL-6 differs from hIL-6 in that vIL-6 is secreted from the cell more slowly and accumulates in the endoplasmic reticulum (ER), where it can signal intracellularly through the gp130 subunit of the IL-6 receptor (IL-6R) (12, 24). To better understand how vIL-6 interacts with the MUT056399 host cell, we previously identified a cellular protein called hypoxia-upregulated protein 1 (HYOU1) that plays a critical role in vIL-6-mediated signaling, survival, and migration (25). Two other host proteins, VKORC1v2 and calnexin, have also been identified as vIL-6-interacting partners, and these cellular proteins appear to play a role in MUT056399 vIL-6-mediated cell survival and vIL-6 folding and intracellular retention, respectively (12, 26, 27). We wanted to investigate how intracellular expression of vIL-6 impacts.