Expression of MHC Ⅱ on rat corneal keratocytes is inhibited by special siRNA targeting CⅡTA

AIM: To investigate the feasibility to inhibit the expression of MHCⅡ by special siRNA targeting class Ⅱ major histocompatibility complex (MHC Ⅱ) transactivator (CⅡTA), which might regulate MHC Ⅱexpression for suppressing immune rejection. METHODS: Five different siRNA were designed, synthesized and transfected into freshly isolated rat corneal keratocytes. At 24 hours posttransfection, the changes of MHC Ⅱexpression were detected by flowcytometry, and the mRNA abundance of CⅡTA and MHC Ⅱ was measured by FQ-PCR after inducing with recombinant rat interferon-gamma (IFN-γ). RESULTS: Different siRNA showed different reduction in MHC Ⅱ and CⅡTA expression compared with the control (P<0.01). Among the five groups, the siRNA-4 was the most efficient. The mRNA content of CⅡTA and MHC Ⅱ were reduced by 95.10%±1.25% and 82.70%±1.95% respectively and the expression of MHC Ⅱ was inhibited by over 80% in siRNA-4 group at 24 hours posttransfection. CONCLUSIONS: The special siRNA targeting to CⅡTA inhibits CⅡTA mRNA and further inhibits its regulation of MHC Ⅱ molecular expression. The blockade of MHC Ⅱ by siRNA may be useful for further studying allogeneic corneal limbal transplantation.     

Effects of hypoxia and hypercapnia on expression of soluble guanylate cyclase in rat pulmonary artery

AIM:To investigate the expression of soluble guanylate cyclase protein and its mRNA in rat pulmonary artery after exposure to hypoxia and hypercapnia.METHODS:Male Sprague-Dawley rats were randomly split into 4 group, which were hypoxic hypercapnic (HH 1 week, HH 2 weeks, HH 4 weeks) group and control group, to copy pulmonary hypertensive animal model. The expression of sGCα₁ and β₁ subunits protein of medial and small pulmonary artery was performed by immunohistochemistry with a polycolonal antibody. In situ hybridization was performed on the rat lung tissue using sGC oligonuclear probe to assay the expression of sGCα₁subunit mRNA.RESULTS:The sGCα₁ and β₁ subunits protein and sGCα₁ subunit mRNA were faint staining in the pulmonary small and medium artery in HH1 week, HH 2 weeks and HH 4 weeks groups compared with control group (all P＜0.01).CONCLUSION:sGC subunit mRNA and protein expression in pulmonary small and medium artery were decreased after exposure to hypoxia and hypercapnia, which took part in the development of the pulmonary hypertension.     

Apoptosis and its modulation in type Ⅰ diabetes mellitus

Apoptosis, also known as programmed cell death, is a normal process contributing to tissue tumor during development and in the adult.During development apoptosis is involved in tissue homeostasis and eliminating nonfunctional, superfluous or harmful cells. It is an active process controlled by some gene and factors such as caspases, bcl-2, Fas/FasL and NO. Type 1 diabetes mellitus is regarded as a chronic autoimmune disease resulting from progressive destruction of insulin-producing β-cells in the pancreas. The relationship between apoptosis with its modulation and type 1 diabetes mellitus was reviwed.     

Some recent advances in the molecular mechanisms underlying senescence

Aging or senescence is a process in which individuals undergo an exponential decline in vitality, leading to death. Recent years, much progress on the molecular mechanisms underlying senes-cence have been made. (1) Some senescence-related gene such as SEN6A, hic-5, dinl and MORF 4 have been clarified; (2) In 1997, through a set of experiments sponsered scientists of Department of Bi-ology Massachusetts Institute of Technology, it was found that the accommulation of extrachromosomal r DNA circles (ERC) in budding yeast s nucleolus is responsible for cell- senescence and the researchers propose that when enough of these circles accumulate, they clog the nucleus and prevent the cell from reading or eplicating its genome, causing it to stop dividing and ultimately to die; (3) In another work finished National Institute on Aging and the Geron biotech company of Melo, it was proved that a cell s biological clock, which tells the cell how and how many times to divide, lies in its telon eres, little bits of DNA that coat the tips of the chromosome and it was clarified that a powerful enzyme, telomerase, with the potential to rejuvenate the human boss aging tissues could effectively extend the shortened telomere.Although there is a long way to go, scientists still believe that it will be made reality in the future to greatly extend the life-span of human.     

Effects of a pentanucleotide repeat polymorphism of the apolipoprotein (a)gene on serum levels of lipoproteins in healthy Han population

AIM:To understand the relationship between pentanucleotide repeat(PNR) polymorphism of the apolipoprotein(a) gene and lipoprotein natures of normal Han population. METHODS:The serum levels of TG, TC, LDL-C,HDL-C, apo AI, apo B and Lp(a) were measured and the polymorphism of the apo(a) PNR was studied by using PCR-SSCP in 153 random normal individuals in Hubei Han population respectively. RESULTS:The relative frequencies of apo(a) PNR allele were significantly different from western population. The apo(a) gene which copy number of PNR is 5 was associated with high Lp(a) levels. No marked differences in the levels of TG, TC,LDL-C, HDL-C, apo AI and apo B were found among the various genotype groups of apo(a) PNR in Hubei Han. CONCLUSION:The data of lipids and PNR polymorphism of the apo(a) gene from healthy Hubei Han were obtained. The apo(a) allele with 5(TTTTA)-repeats may be related to high serum Lp(a) levels in the Hubei Han population.     

Relationship between apolipoprotein E gene polymorphism and sporadic Alzheimer's disease

AIM: To evaluate the association between apolipoprotein E(apoE) gene polymorphism and sporadic Alzheimer's disease (AD). METHOD: A case-control study was undertaken detecting the polymorphism of apoE by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP).RESULTS:(1)The frequencies of 3/4 genotype and 4 al ele in AD were significant ly higher than that in age-matched controls(P<0.05).(2)The frequency of G/G genotype for apoE IE1 in AD was significantly higher than that in age-mat ched control(P<0.05).(3)The apoE 4 al ele was associated with a tripling of the risk for AD compared with no 4 allele(odd ratio 2.932, 95%CI 1.379~6.226);Homozygosity of the G allele in IE1 was associated with adoubling of the risk for AD compared with the G/C and C/C genotypes(odd rat io 2.223, 95%CI 1.075~4.599).However, the IE1 G al ele is also closely associated with apoE 4.When the sample was split on the basis of apo Egenotype, the associat ion between IE1 G/G genotype and AD was no longer statistically significant.CONCLUSION: ApoE ε4 was a risk factor of AD, and the apparent association between IE1 G/G and AD is a consequence of the association between the ε4 and IE1 G/G genotype.     

Antiproliferative effect of c-myc antisense oligonucleotide in rat thymus lymphocytes

AIM: To observe the antiproliferative effect of c-myc antisense oligonucleotide in rat thymus lymphocytes. METHODS: Rat thymus lymphocytes were separated by Ficoll-Urografin density gradient centrifugation. Lipofectin was used to introduce antisense, sense and mismatched oligonucleotides for c-myc to rat thymus lymphocytes. The antiproliferative effect was assayed by incorporation of [³H]-TdR and MTS cell proliferation assay. TR-PCR was used to detect the expression of c-myc mRNA. RESULTS: c-myc antisense oligonucleotide inhibited ratthymus lymphocytes proliferation[(0.14±0.03)A vs(0.32±0.16)A,P<0.05],but this ef ect had no relationship with the concentration of c-myc antisense oligonucleot ide.c-myc antisense oligonucleotide decreased the expression of c-myc mRNA in rat thymus lymphocytes. CONCLUSION: c-myc antisense oligonucleotide inhibited rat thymus lymphocyte proliferation.