Publications

Class IIa histone deacetylases (HDACs) regulate a variety of cellular processes, including cardiac growth, bone development, and specification of skeletal muscle fiber type. Multiple serine/threonine kinases control the subcellular localization of these HDACs by phosphorylation of common serine residues, but whether certain class IIa HDACs respond selectively to specific kinases has not been determined. Here we show that calcium/calmodulin-dependent kinase II (CaMKII) signals specifically to HDAC4 by binding to a unique docking site that is absent in other class IIa HDACs. Phosphorylation of HDAC4 by CaMKII promotes nuclear export and prevents nuclear import of HDAC4, with consequent derepression of HDAC target genes. In cardiomyocytes, CaMKII phosphorylation of HDAC4 results in hypertrophic growth, which can be blocked by a signal-resistant HDAC4 mutant. These findings reveal a central role for HDAC4 in CaMKII signaling pathways and have implications for the control of gene expression by calcium signaling in a variety of cell types.

Development of nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) infection. However, NPC occurs with a marked geographic and racial distribution, whereas EBV infection is ubiquitous in the world. This leads to a question whether certain subtypes of EBV have a greater potential to induce cell transformation. Latent membrane protein 1 (LMP1) is an EBV-encoded oncogenic protein and its 30-bp deleted variant (del-LMP1) has been reported to be predominant in biopsies of NPC. We have assessed the polymorphism of LMP1 in 47 biopsies of NPC, 107 cases of throat washings (TWs) from NPC patients, and 106 cases of TWs from non-NPC patients in Guangzhou, an endemic area of NPC in southern China, as well as 103 cases of TWs from healthy donors in Haerbin, a non-endemic area of NPC in northern China. Our results found a similar extent of the LMP1 polymorphism between NPC patients and non-NPC patients in Guangzhou, with the del-LMP1 being predominant in both Guangzhou and Haerbin. Sequence analyses showed identical substitutions in other coding regions of the del-LMP1 isolated from Guangzhou and Haerbin. These results indicate that del-LMP1 represents a geographic or race-associated polymorphism rather than an NPC disease phenotype-associated polymorphism.

To develop the genetic rescue techniques for infectious bursal disease virus (IBDV), Birnaviridae family, the full-length cDNA of the larger segment of the chicken IBDV was amplified and cloned by long RT-PCR. A comparison of four purification and extraction methods of RNA from IBDV infected chicken embryoid fibroblasts (CEF) showed that the ultracentrifugation followed by proteinase Kdigestion extracted dsRNA more effectively. Then reverse transcription was carried out at 50 degrees using Superscipt II enzyme, followed by RNase H digestion. Amplification of single stranded cDNA in a single step resulted in the synthesis of the full-length segment A of 3 259 bp. The amplified product was cloned and sequenced, identifying that it was an IBDV. This method is superior to other methods based on amplifying different parts of the genome many times, therefore the cloning procedure was simplified.

VP2 cDNA gene of the infectious bursal disease virus HZ96 strain, encoding a major host-protective antigen, was cloned into baculovirus transfer vector pBacPAK8, resulting in a recombinant transfer vector pBacPAK-VP2. The vector pBacPAK-VP2 and linearized DNA of modified baculovirus Bm-BacPAK6 were co-transfected into the cultured Bombyx mori (Bm) N cells, in which homologous recombination occurred. Then, baculovirus recombinants were screened out. The Bm cells and Bm larvae were infected with the baculovirus recombinant that can expresse VP2, and Bm N cells and haemolymph of Bm larvae were collected for assays. The results of ELISA and Western immunoblotting assays demonstrated that VP2 was expressed in the cultured Bm cells and the Bm larvae.