The ubiquitin/26S proteasome system plays an essential role not only in maintaining protein turnover, but also in regulating many other plant responses, including plant–pathogen interactions. Previous studies highlighted different roles of the 20S proteasome in plant defense during virus infection, either indirectly through viral suppressor-mediated degradation of Argonaute proteins, affecting the RNA interference pathway, or directly through modulation of the proteolytic and RNase activity of the 20S proteasome, a component of the 20S proteasome, by viral proteins, affecting the levels of viral proteins and RNAs. Here we show that MG132, a cell permeable proteasomal inhibitor, caused an increase in papaya ringspot virus (PRSV) accumulation in its natural host papaya (Carica papaya). We also show that the PRSV HcPro interacts with the papaya homologue of the Arabidopsis PAA (α1 subunit of the 20S proteasome), but not with the papaya homologue of Arabidopsis PAE (α5 subunit of the 20S proteasome), associated with the RNase activity, although the two 20S proteasome subunits interacted with each other. Mutated forms of PRSV HcPro showed that the conserved KITC54 motif in the N-terminal domain of HcPro was necessary for its binding to PAA. Co-agroinfiltration assays demonstrated that HcPro expression mimicked the action of MG132, and facilitated the accumulation of bothtotal ubiquitinated proteins and viral/non-viral exogenous RNA in Nicotiana benthamiana leaves. These effects were not observed by using an HcPro mutant (KITS54), which impaired the HcPro – PAA interaction. Thus, the PRSV HcPro interacts with a proteasomal subunit, inhibiting the action of the 20S proteasome, suggesting that HcPro might be crucial for modulating its catalytic activities in support of virus accumulation.

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Heck's disease or focal epithelial hyperplasia is a rare, benign and asymptomatic lesion of oral mucosa that is characterized by the presence of soft, sessile papules, white to pinkish in colour that occur diffusely in oral cavity. Prevalence rate of this disease greatly varies from one geographic region to another. It is found to be closely associated with human papilloma virus (HPV). This paper reports an Indian case of focal epithelial hyperplasia in a 5-year-old boy that is diagnosed according to both clinical and histopathological features, where human poillomavirus (HPV) subtype 32 was found associated with disease through polymerase chain reaction analyses. A dental practitioner should be aware of this disease and must perform a careful evaluation both clinically and histopathologically for setting the diagnosis with other diseases. How to cite this article Nallanchakrava S, Sreebala N, Basavaraj, Sindgi F. Laser Excision of Focal Epithelial Hyperplasia (Heck's Disease): A Rare Case Report. Int J Clin Pediatr Dent, 2018;11(6):526-528