Functional analysis the role of the Kaposi sarcoma‐associated virus vBcl‐2 protein in cellular apoptosis (1010.13)

Kaposi’s sarcoma‐associated herpesvirus (KSHV) is a transforming virus associated with various cancers, the most common being the skin cancer Kaposi’s sarcoma. KSHV viral proteins are known to disrupt many normal cellular pathways in the human host. One specific target is the apoptotic pathway, or the programed cell death process. The cellular Bcl‐2 family proteins, critical components of apoptotic signaling, converge at the mitochondria. This broad family of proteins is comprised of both pro‐ and anti‐apoptotic proteins, sharing homology in four conserved trans‐membrane domains, BH1‐BH4. KSHV encodes a protein, vBcl2, with functional and sequential homology to the anti‐apoptotic Bcl‐2 protein. This gene is expressed in the early stages of the viral lytic cycle and has been shown to affect the progression of apoptotic signaling in order to allow for proper viral replication and virion production. We analyzed the interaction between KSHV’s vBcl‐2 protein and a human protein, BIK, a member of the BH3 only family of pro‐apoptotic proteins. BIK has significant antitumor activity, mediated by its BH3 domain. Mutant constructs of both the viral vBcl‐2 protein and the human BIK protein were screened in a yeast two‐hybrid protein interaction assay to determine the critical residues required for interaction. Using fluorescent microscopy we determined the cellular localization of both wild type and mutant BIK proteins with respect to the vBcl2 protein. Understanding more fully the interaction between vBcl‐2 and BIK can illuminate the role vBcl‐2 and the BH3 only family of proteins play in the viral pathway to cancer, providing new information about the process of tumor development.