K1 and K15 of Kaposi's Sarcoma-Associated Herpesvirus Are Partial Functional Homologues of Latent Membrane Protein 2A of Epstein-Barr Virus.

UNLABELLED: The human herpesviruses Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are associated with Hodgkin's lymphoma (HL) and Primary effusion lymphomas (PEL), respectively, which are B cell malignancies that originate from germinal center B cells. PEL cells but also a quarter of EBV-positive HL tumor cells do not express the genuine B cell receptor (BCR), a situation incompatible with survival of normal B cells. EBV encodes LMP2A, one of EBV's viral latent membrane proteins, which likely replaces the BCR's survival signaling in HL. Whether KSHV encodes a viral BCR mimic that contributes to oncogenesis is not known because an experimental model of KSHV-mediated B cell transformation is lacking. We addressed this uncertainty with mutant EBVs encoding the KSHV genes K1 or K15 in lieu of LMP2A and infected primary BCR-negative (BCR(-)) human B cells with them. We confirmed that the survival of BCR(-) B cells and their proliferation depended on an active LMP2A signal. Like LMP2A, the expression of K1 and K15 led to the survival of BCR(-) B cells prone to apoptosis, supported their proliferation, and regulated a similar set of cellular target genes. K1 and K15 encoded proteins appear to have noncomplementing, redundant functions in this model, but our findings suggest that both KSHV proteins can replace LMP2A's key activities contributing to the survival, activation and proliferation of BCR(-) PEL cells in vivo. IMPORTANCE: Several herpesviruses encode oncogenes that are receptor-like proteins. Often, they are constitutively active providing important functions to the latently infected cells. LMP2A of Epstein-Barr virus (EBV) is such a receptor that mimics an activated B cell receptor, BCR. K1 and K15, related receptors of Kaposi's sarcoma-associated herpesvirus (KSHV) expressed in virus-associated tumors, have less obvious functions. We found in infection experiments that both viral receptors of KSHV can replace LMP2A and deliver functions similar to the endogenous BCR. K1, K15, and LMP2A also control the expression of a related set of cellular genes in primary human B cells, the target cells of EBV and KSHV. The observed phenotypes, as well as the known characteristics of these genes, argue for their contributions to cellular survival, B cell activation, and proliferation. Our findings provide one possible explanation for the tumorigenicity of KSHV, which poses a severe problem in immunocompromised patients.

Overgeneralizing emotions: Facial width-to-height revisited.

Facial width-to height ratio (fWHR), presumed to be shaped by testosterone during puberty, has been linked with aggressive, dominant, and power-seeking behavioral traits in adult males, although the causal mediation is still being disputed. To investigate the role of mere observer attribution bias in the association, we instructed participants to draw, feature-assemble, or photo-edit faces of fictitious males with aggressive-dominant character (compared with peaceloving-submissive), or powerful social status (compared with powerless). Across three studies involving 1,100 modeled faces in total, we observed little evidence for attribution bias with regards to facial width. Only in the photo-edited faces did character condition seem to affect fWHR; this difference, however, relied on displayed state emotions, not on static facial features. Anger, in particular, was expressed by lowered or V-shaped eyebrows, whereby facial height was reduced so that fWHR increased, relative to the comparison condition where the opposite happened. Using Bayesian analyses and equivalence testing, we confirmed that, in the absence of state emotionality, there was no effect of character condition on facial width. Our results add to a number of recent studies stressing the role of emotion overgeneralization in the association of fWHR with personality traits, an attributional bias that may give rise to a self-fulfilling prophecy. Methodologically, we infer that static images may be of limited use for investigations of fWHR because they cannot sufficiently differentiate between transient muscular activation and identity-related bone structures. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Effects of artesunate on cytokinesis and G2/M cell cycle progression of tumour cells and budding yeast.

Artesunate, a semi-synthetic derivative of artemisinin, is an effective and safe anti-malaria drug, which also exhibits activity towards cancer cells. The present investigation studied the effect of artesunate on the mitosis of cancer and yeast cells by fluorescence microscopy and mRNA microarrays with a focus on the mitotic spindle checkpoint. The cytotoxicity of artesunate towards seven cell lines from six different cancer types was determined using the XTT assay. Furthermore, the cell cycle distribution of artesunate-treated cells was investigated by flow cytometry and immunofluorescence. To elucidate the genes mediating the effect of artesunate in the mitotic spindle checkpoint, knockout mutants of Saccharomyces cerevisiae were generated, since yeast knockouts are easier to generate than knockout strains of mammalian cells. Four out of the seven tested cell lines showed a G2/M arrest upon artesunate exposure. Cells residing in the G2/M arrest revealed multiple centrosomes, small multiple spindles and multi-nucleated cells, suggesting a defect in cytokinesis. The mitotic spindle checkpoint genes bub1, bub2, bub3, mad1, mad2 and mad3 were individually deleted and the sensitivity of these mutants towards artesunate was determined by monitoring the cell growth. The Δbub3 and Δmad3 mutants showed an increased sensitivity and the Δmad2 mutant a slightly decreased sensitivity to artesunate in comparison to the respective wild type. Bub3, Mad3 and Mad2 are the main regulators of the mitotic spindle checkpoint, suggesting that artesunate may interfere with this control mechanism.