Extranuclear Translocation of High-Mobility Group A1 Reduces the Invasion of Extravillous Trophoblasts Involved in the Pathogenesis of Preeclampsia: New Aspect of High-Mobility Group A1.

OBJECTIVE: High-mobility group A1 (HMGA1) protein is known to express in trophoblast; however, the role of migration has not been reported to date. In this study, we investigated the role of HMGA1 on the pathogenesis of preeclampsia using immortalized human trophoblast cell (HTR-8/SVneo). MATERIALS AND METHODS: We investigated HMGA1 expression in cytotrophoblasts derived from our preeclampsia model mouse, the CD40L mouse, using immunofluorescence. Wound healing and transwell migration assays were also performed using HTR-8/SVneo (extravillous trophoblast) cells transfected with DNA or siRNA of HMGA1. The effect of extranuclear translocation of HMGA1 on the migration of extravillous trophoblastic cells was evaluated using deoxycholic acid (DCA). RESULTS: HMGA1 was expressed exclusively in the nuclei of trophoblasts derived from control mice; cytoplasmic expression was observed only in CD40L mice with preeclampsia. Furthermore, overexpression of HMGA1 in the nuclei of HTR-8/SVneo cells stimulated cell proliferation and migration. Translocation of nuclear HMGA1 to cytoplasm treated with DCA reduced cell migration. CONCLUSIONS: Collectively, these findings demonstrate that proper subcellular localization of HMGA1 is important for its function in trophoblast cells, and suggest that aberrant cytoplasmic expression of HMGA1 contributes to the pathogenesis of preeclampsia through impairment of trophoblast migration.

Generation and Characterization of UL21-Null Herpes Simplex Virus Type 1.

UL21 of herpes simplex virus type 1 (HSV-1) is an accessory gene that encodes a component of the tegument. Homologs of this protein have been identified in the alpha, beta, and gamma herpesvirus subfamilies, although their functions are unclear. To clarify the functions of UL21, we generated a UL21-null HSV-1 mutant. Growth analysis showed that the synthesis of infectious UL21-null HSV-1 in glial cells was delayed and that the overall yield was low. The plaque sizes of the UL21-null mutant were smaller than those of wild-type HSV-1. We identified several candidate UL21-interacting proteins, including intermediate filaments, by yeast two-hybrid screening. The distribution of glial fibrillary acidic protein (GFAP), which is the main component of intermediate filaments, was altered in UL21-null mutant-infected glial cells compared to wild-type virus-infected cells. These results will help clarify the function of UL21 and broaden our understanding of the life cycle of HSV.

Herpes simplex virus type 1 UL14 tegument protein regulates intracellular compartmentalization of major tegument protein VP16.

BACKGROUND: Herpes simplex virus type 1 (HSV-1) has a complicated life-cycle, and its genome encodes many components that can modify the cellular environment to facilitate efficient viral replication. The protein UL14 is likely involved in viral maturation and egress (Cunningham C. et al), and it facilitates the nuclear translocation of viral capsids and the tegument protein VP16 during the immediate-early phase of infection (Yamauchi Y. et al, 2008). UL14 of herpes simplex virus type 2 exhibits multiple functions (Yamauchi Y. et al, 2001, 2002, 2003). METHODS: To better understand the function(s) of UL14, we generated VP16-GFP-incorporated UL14-mutant viruses with either single (K51M) or triple (R60A, R64A, E68D) amino acid substitutions in the heat shock protein (HSP)-like sequence of UL14. We observed the morphology of cells infected with UL14-null virus and amino acid-substituted UL14-mutant viruses at different time points after infection. RESULTS: UL14(3P)-VP16GFP and UL14D-VP16GFP (UL14-null) viruses caused similar defects with respect to growth kinetics, compartmentalization of tegument proteins, and cellular morphology in the late phase. Both the UL14D-VP16GFP and UL14(3P)-VP16GFP viruses led to the formation of an aggresome that incorporated some tegument proteins but did not include nuclear-egressed viral capsids. CONCLUSIONS: Our findings suggest that a cluster of charged residues within the HSP-like sequence of UL14 is important for the molecular chaperone-like functions of UL14, and this activity is required for the acquisition of functionality of VP16 and UL46. In addition, UL14 likely contributes to maintaining cellular homeostasis following infection, including cytoskeletal organization. However, direct interactions between UL14 and VP16, UL46, or other cellular or viral proteins remain unclear.