OBJECTIVETo investigate the role of a potential diabetes-related mitochondrial region, which includes two previously reported mutations, 3243A-->G and 3316G-->A, in Chinese patients with adult-onset type 2 diabetes.

METHODSA total of 277 patients and 241 normal subjects were recruited for the study. Mitochondrial nt 3116 - 3353, which spans the 16S rRNA, tRNA(leu(UUR)) and the NADH dehydrogenase 1 gene, were detected using polymerase chain reaction (PCR), direct DNA sequencing, PCR-restriction fragment length polymorphism and allele-specific PCR. Variants were analyzed by two-tailed Fisher exact test. The function of the variants in 16S rRNA were predicted for minimal free energy secondary structures by RNA folding software mfold version 3.

RESULTSFour homoplasmic nucleotide substitutions were observed, 3200T-->C, 3206C-->T, 3290T-->C and 3316G-->A. Only the 3200T-->C mutation is present in the diabetic population and absent in the control population. No statistically significant associations were found between the other three variants and type 2 diabetes. The 3200T-->C and 3206C-->T nucleotide substitutions located in 16S rRNA are novel variants. The 3200T-->C caused a great alteration in the minimal free energy secondary structure model while the 3206C-->T altered normal 16S rRNA structure little.

CONCLUSIONSThe results suggest that the 3200T-->C mutation is linked to the development of type 2 diabetes, but that the other observed mutations are neutral. In contrast to the Japanese studies, the 3316G-->A does not appear to be related to type 2 diabetes.

Age of Onset ; Aged ; Alleles ; Base Sequence ; DNA Mutational Analysis ; DNA, Mitochondrial ; chemistry ; genetics ; Diabetes Mellitus, Type 2 ; genetics ; Humans ; Middle Aged ; Models, Molecular ; Nucleic Acid Conformation ; Point Mutation ; Polymerase Chain Reaction ; methods ; Polymorphism, Restriction Fragment Length ; RNA, Ribosomal, 16S ; chemistry ; genetics

Epstein-Barr virus (EBV) infection is closely associated with undifferentiated nasopharyngeal carcinoma (NPC), strongly implicating a role for EBV in NPC pathogenesis; conversely, EBV infection is rarely detected in normal nasopharyngeal epithelial tissues. In general, EBV does not show a strong tropism for infecting human epithelial cells, and EBV infection in oropharyngeal epithelial cells is believed to be lytic in nature. To establish life-long infection in humans, EBV has evolved efficient strategies to infect B cells and hijack their cellular machinery for latent infection. Lytic EBV infection in oropharyngeal epithelial cells, though an infrequent event, is believed to be a major source of infectious EBV particles for salivary transmission. The biological events associated with nasopharyngeal epithelial cells are only beginning to be understood with the advancement of EBV infection methods and the availability of nasopharyngeal epithelial cell models for EBV infection studies. EBV infection in human epithelial cells is a highly inefficient process compared to that in B cells, which express the complement receptor type 2 (CR2) to mediate EBV infection. Although receptor(s) on the epithelial cell surface for EBV infection remain(s) to be identified, EBV infection in epithelial cells could be achieved via the interaction of glycoproteins on the viral envelope with surface integrins on epithelial cells, which might trigger membrane fusion to internalize EBV in cells. Normal nasopharyngeal epithelial cells are not permissive for latent EBV infection, and EBV infection in normal nasopharyngeal epithelial cells usually results in growth arrest. However, genetic alterations in premalignant nasopharyngeal epithelial cells, including p16 deletion and cyclin D1 overexpression, could override the growth inhibitory effect of EBV infection to support stable and latent EBV infection in nasopharyngeal epithelial cells. The EBV episome in NPC is clonal in nature, suggesting that NPC develops from a single EBV-infected nasopharyngeal epithelial cell, and the establishment of persistent and latent EBV infection in premalignant nasopharyngeal epithelium may represent an early and critical event for NPC development.
Carcinoma ; Cell Transformation, Neoplastic ; Cells, Cultured ; Epithelial Cells ; Epstein-Barr Virus Infections ; Herpesvirus 4, Human ; Humans ; Nasopharyngeal Neoplasms ; Nasopharynx ; Precancerous Conditions

OBJECTIVETo investigate the role of lipoprotein lipase (LPL) gene on Chinese patients with hypertriglyceridemic type 2 diabetes.

METHODSThree subject groups, including hypertriglyceridemic group, normalipidemic type 2 diabetes group and healthy controls, were recruited and screened for sequence changes in LPL gene with PCR, SSCP, restriction analysis and direct DNA sequencing. LPL mass and activity in post-heparin plasma and in in vitro expression were investigated. Comparative modeling was performed via Swiss-PDB Viewer to provide the potential 2-D structures of wildtype and mutant proteins.

RESULTSFour missense mutations, Ala71Thr, Val18Ile, Gly188Glu and Glu242Lys, were identified in patients with hypertriglyceridemic type 2 diabetes, and not in both normalipidemic diabetes and the control subjects. The four missense mutations were located in the highly conserved amino acid sites, which are involved in highly conserved exon 3, 5, or 6 regions. They led to reduced LPL mass and enzyme activities in both post-heparin plasma and in vitro expression. The modeled structures displayed the differences to a great extent between the mutant and wide-type molecules.

CONCLUSIONThese results indicated that the 4 missense mutations lead to LPL deficiency and subsequent hypertriglyceridemia. The LPL deficiency predispose a progressive diabetic pathway to those affected individuals. LPL gene is one of susceptibility gene for hypertriglyceridemic type 2 diabetes.

Asian Continental Ancestry Group ; Diabetes Mellitus, Type 2 ; complications ; genetics ; Female ; Genetic Predisposition to Disease ; Humans ; Hypertriglyceridemia ; complications ; enzymology ; genetics ; Lipoprotein Lipase ; genetics ; Male ; Middle Aged ; Mutation, Missense ; Polymerase Chain Reaction ; Polymorphism, Single-Stranded Conformational