Biology Reference
In-Depth Information
Vliegen et al. 2004). CMV also encodes CC and CXC chemokine homologs (see the
chapter by P.S. Beisser et al., this volume) that recruit a multitude of host cellular
infiltrates (Sparer et al. 2004; Noda et al. 2006). In addition, CMV modifies a number
of other cellular factors involved in angiogenesis and wound repair processes, including
adhesion molecules (ICAM-1, VCAM-1, VAP-1, and E-selectin) and growth
factors and receptors (TGF-
, PDGF-AA, VEGF, and PDGFR) (Shahgasempour
et al. 1997; Burns et al. 1999; Zhou et al. 1999; Inkinen et al. 2003, 2005;
Helantera et al. 2005, 2006; Reinhardt et al. 2005a, 2005b). In addition, increased
matrix metalloproteinase (MMP)-2 activity is observed in HCMV-infected cells in
conjunction with a reduction in matrix gene expression, resulting in a malleability
to SMC migration, an alteration in vessel remodeling that promotes a vasculopa-
thy (Schaarschmidt et al. 1999; Reinhardt et al. 2006). The upregulation of agents
that initiate endothelial adhesion and those that promote wound healing provides
a means for CMV to enhance the adherence and infiltration of inflammatory cells
that drive vascular disease.
β
What Factors Constitute the HCMV Secretome?
We and others have demonstrated that HCMV infection alters the types and
quantities of bioactive proteins released from infected cells, which we designate as
the HCMV secretome. Many of these factors have important roles in vascular
disease, and we hypothesize that a major role of CMV infection in the acceleration
of TVS occurs through the increased production of WH and AG factors in the allo-
graft. However, neither the complete proteome of the HCMV secretome nor its
effects on WH and AG are known. Therefore, in order to determine the effects of
HCMV infection on the extracellular milieu, we generated secretomes from HCMV-
infected and mock-infected fibroblasts and determined their protein contents
(proteomes) by gel-free LC-MS/MS at the Pacific Northwest National Laboratory
(PNNL, Richland, WA) and by specific protein arrays. In our LC-MS/MS analysis
of the HCMV-infected and mock-infected secretomes, we identified more than
1,200 proteins with 800 having two or more peptide hits. Of the proteins identified
by MS/MS, more than 1,000 were specific or highly enriched in the HCMV secre-
tome, more than 260 proteins were common to both the HCMV- and mock-infected
secretomes, and more than 225 were specific for the mock-infected secretome. We
detected ten viral proteins in the HCMV secretome of which only four were identi-
fied with more than peptides, including UL32 (pp150), UL44, UL122, and UL123.
Overlaying pathway information and literature mining results, it was noted that a
cluster of proteins were involved in integrin signaling and that this cluster was
enriched for laminins. Laminins are widely distributed ECM proteins involved in
cell adhesion signaling and have recently been implicated in playing a fundamental
role in angiogenesis by directly affecting gene and protein expression profiles
(Folkman 2003). TGF-
β
signaling and angiogenesis pathways were also identified
in this initial screen.
