Age-dependent alterations in mRNA level and promoter methylation of collagen alpha1(I) gene in human periodontal ligament

In an attempt to understand the molecular mechanisms of age-dependent degenerative alteration in human periodontal tissues, we examined mRNA level and DNA methylation of collagen alpha1(I) gene. Using healthy periodontal ligament tissues from humans aged 9-76 years, we found that the collagen alpha1(I) mRNA level decreased almost linearly with age. It was observed in both Northern blot and dot blot hybridization. Examination of DNA methylation in the collagen alpha1(I) gene promoter region by its susceptibility to methylation-sensitive restriction enzyme followed by Southern blot analysis showed age-dependent increase of DNA methylation at -1705 and -80 positions located upstream of the gene. The data suggest the possible importance of alterations in collagen alpha1(I) gene expression and its DNA methylation in promoter region in age-dependent degeneration of periodontal ligament.     

胆道闭锁患儿外周血T细胞ITGAL基因启动子区甲基化状态及其mRNA表达

目的研究胆道闭锁（BA）患儿外周血T细胞ITGAL基因启动子区DNA甲基化状态及其对mRNA表达的影响。方法选取2010年4~8月于复旦大学附属儿科医院（我院）初诊、并经外科手术病理学检查证实为BA的患儿为研究对象,分为BA组和甲基化结果验证组;选取我院同期行斜疝手术、日龄≤120 d和肝功能、肾功能正常的患儿为对照组。分离BA组和对照组CD4＋和CD8＋T细胞,提取DNA和RNA,行ITGAL基因启动子区DNA甲基化水平和mRNA表达水平检测。甲基化结果验证组分离细胞后,予5-氮杂胞苷干预和培养后,行甲基化水平和mRNA表达水平检测,验证研究结果。结果 BA组和对照组各20例进入研究,两组年龄和性别均匹配。①BA组和对照组CD4＋和CD8＋T细胞ITGAL基因启动子序列-250~250 bp均未发生甲基化。BA组CD4＋T细胞-1450~-950 bp的CG二核苷酸平均甲基化水平显著高于CD8＋T细胞（0.94vs0.75,P=0.02）,也显著高于对照组CD4＋T细胞（0.94vs0.66,P〈0.001）。②BA组外周血CD4＋T细胞ITGALmRNA表达显著低于CD8＋T细胞（0.021±0.002vs0.032±0.004,P=0.013）,也显著低于对照组（0.021±0.002vs0.031±0.003,P=0.007）。BA组CD8＋T细胞ITGALmRNA表达与对照组差异无统计学意义（0.032±0.004vs0.034±0.006,P=0.266）。③甲基化验证组纳入5例BA患儿。验证结果显示,5-氮杂胞苷干预后CD4＋和CD8＋T细胞ITGAL启动子区平均甲基化水平均显著低于未予5-氮杂胞苷干预的水平;ITGALmRNA的表达均显著高于未予5-氮杂胞苷干预的水平。结论 BA患儿外周血CD4＋T细胞ITGAL启动子区发生高甲基化,并对mRNA表达产生影响。     

Age-dependent covenant DNA alterations (I-compounds) in rat liver mitochondrial DNA

Rat liver mitochondrial (mt) DNA was investigated for the presence of I-compounds, a recently discovered type of DNA modifications which is detected and measured via ³²P-postlabeling. These DNA modifications were previously shown to accumulate in an age-dependent manner in total cellular DNA of various tissues of untreated rodents. In the present work, mt DNA of 1-, 3-, 6-, and 9-month-old female Sprague-Dawley rats was found by ³²P-postlabeling also to contain I-compounds that increase with age. Most of the I-compounds were identical for mt and nuclear (nu) DNA. A cluster of 2 non-polar I-spots (termed M-compounds) was mitochondria-specific and increased about 8-fold from 1 to 9 months, attaining a RAL value of 44 × 10⁻⁹ or 1 modification in 2.3 × 10⁷ DNA nucleotides at 9 months. Quantitative differences between chromatographically identical spots were seen mainly for a low-polarity fraction of I-compounds, which exhibited 2 times higher overall levels in mt DNA versus nu DNA over the age range studied. Total I-compound levels increased during this time 6.9- and 5.1-fold in nuclei and mitochondria, respectively. The M-compound level was close to 10% of total mt DNA I-compound levels. M-compounds may conceivably be derived from potentially DNA-reactive electron carriers of the mt electron-transport chain, while I-compounds common to both mt and nu DNA presumaly originate in extramitochondrial sources. The similarity of mitochondrial and nuclear I-compound profiles and amounts implies possible regulatory mechanisms in I-compound formation and repair. Mt DNA maps showed additional ³²P-labeled material which may have been associated with DNA damage caused by oxygen free radicals known to be generated by the mt electron-transport chain. Age-dependent increases of mt DNA modifications are potentially related to mt mutations and may be linked to age-related degenerative changes in mitochondria.     

Age-dependent DNA methylation of genes that are suppressed in stem cells is a hallmark of cancer

Polycomb group proteins (PCGs) are involved in repression of genes that are required for stem cell differentiation. Recently, it was shown that promoters of PCG target genes (PCGTs) are 12-fold more likely to be methylated in cancer than non-PCGTs. Age is the most important demographic risk factor for cancer, and we hypothesized that its carcinogenic potential may be referred by irreversibly stabilizing stem cell features. To test this, we analyzed the methylation status of over 27,000 CpGs mapping to promoters of ∼14,000 genes in whole blood samples from 261 postmenopausal women. We demonstrate that stem cell PCGTs are far more likely to become methylated with age than non-targets (odds ratio = 5.3 [3.8–7.4], P < 10⁻¹⁰), independently of sex, tissue type, disease state, and methylation platform. We identified a specific subset of 69 PCGT CpGs that undergo hypermethylation with age and validated this methylation signature in seven independent data sets encompassing over 900 samples, including normal and cancer solid tissues and a population of bone marrow mesenchymal stem/stromal cells (P < 10⁻⁵). We find that the age-PCGT methylation signature is present in preneoplastic conditions and may drive gene expression changes associated with carcinogenesis. These findings shed substantial novel insights into the epigenetic effects of aging and support the view that age may predispose to malignant transformation by irreversibly stabilizing stem cell features.Targets of polycomb group proteins (PCGTs) are repressed in human embryonic and adult stem cells (Lee et al. 2006). The repression mechanism involves chromatin modifications and is reversible, allowing stem cells and multipotent progenitors to differentiate into committed cell lineages through expression of specific PCGTs. Recently, we and others have demonstrated that stem cell PCGTs in human embryonic stem cells (hESC) are far more likely to undergo cancer-specific promoter DNA hypermethylation than non-targets, suggesting a stem-cell origin model of cancer. In this model, PCGTs in stem cells would gradually undergo de novo methylation, irreversibly locking cells in an undifferentiated state of self-renewal and thereby predisposing them to subsequent malignant transformation (Ohm et al. 2007; Schlesinger et al. 2007; Widschwendter et al. 2007). However, the mechanisms and factors contributing to this de novo methylation are not yet known.Age is by far the strongest demographic risk factor for cancer. Besides time-dependent DNA damage (Hoeijmakers 2009), there is now also substantial evidence that aging affects DNA methylation (DNAm) of specific loci, including cancer-related genes (Issa et al. 1994, 1996; Ahuja et al. 1998; Nakagawa et al. 2001; So et al. 2006; Fraga and Esteller 2007; Fraga et al. 2007; Bjornsson et al. 2008; Christensen et al. 2009). Based on these observations, we hypothesized that age may induce DNAm of PCGTs, and thereby predispose to cancer. Although blood and epithelial cells originate from different germ layers, we speculated that genes that are mandatory for the differentiation of epithelial cells are more likely to become methylated with increasing age in non-epithelial tissue such as blood. Hence, in order to identify age-dependent CpGs that may be important in the biology of epithelial cancers, we first retrieved an age-dependent signature from peripheral blood cells, then validated the age signature in independent blood samples and normal epithelial tissues, and finally tested the biological relevance of this signature in epithelial neoplasias.     

DNA methylation changes during mouse spermatogenesis

Genomic imprinting in mammals is thought to be mediated by differences in the methylation level of cytosine residues in the genome. These differences in DNA methylation are thought to be generated during the development of the germ line. To characterize the profile of global methylation of the mouse genome during male gametogenesis, we have quantified the relative level of methylation in individual cells during meiosis and spermatogenesis. A decrease in the level of DNA methylation is observed from meiotic cells to elongated spermatids. The erasure of the somatic pattern of methylation during spermatogenesis suggests the existence of a subsequent mechanism generating the parental specific methylation patterns leading to genomic imprinting of specific alleles.     

Age-dependent increases of DNA adducts (I-compounds) in human and rat brain DNA

Brain DNA from 20 humans ranging in age from neonatal to 100 years was analyzed by the nuclease P1-enhanced version of the ³²P-postlabeling assay for bulky covalently modified nucleotides. A reproducible pattern of three ³²P-labeled spots was obtained by thin-layer chromatography followed by autoradiography. Two of these spots increased with age (Mann-Whitney U-test; P<0.001; comparison of ages ≤ 60 years and ages > 60 years). Thus, these spots met the definition of I-compounds. Rat brain DNA exhibited the same two I-spots, whose intensities also increased with animal age (1, 4, and 10 months). In humans, considerable individual variation of brain I-compound levels was observed, especially at ages > 60 years, presumably reflecting environmental, life-style, or genetic factors. This variation was not noted for brain DNA of laboratory rats. Thus, human brain DNA undergoes progressive covalent modifications with aging.     

High density DNA methylation array is a reliable alternative for PCR-based analysis of the MGMT promoter methylation status in glioblastoma

AimMGMT promoter methylation status is an important biomarker predicting survival and response to chemotherapy in patients suffering from glioblastoma. Since new diagnostic methods such as methylome-based classification of brain tumors are more and more frequently performed, we aimed at comparing the suitability of calculating the MGMT promoter methylation status in a quantitative manner from the methylome profiling as compared to the classic gold standard assessment by PCR.MethodsOur cohort consisted of 39 cases diagnosed as “glioblastoma, IDH-wildtype” of which the MGMT promoter methylation status was analyzed with both methylation-specific PCR and high density DNA methylation array using the STP-27 algorithm. Contradictory results were validated by pyrosequencing.ResultsThe inter-method reliability reached 77% (kappa-coefficient: 0.58) when also cases with an inconclusive result in one or the other method were taken into account. When only cases with conclusive results in both methods were considered, a very high inter-method reliability of 91% (kappa-coefficient: 0.86) could be achieved. For “methylated” cases, no contradictory results were obtained. For the remaining two cases with discrepant results subsequent pyrosequencing analyses spoke in favor of each previously applied method once.ConclusionIn addition to its benefits for molecular subgrouping and copy number analysis of brain tumors, DNA-methylation based classification is a highly reliable tool for the assessment of MGMT promoter methylation status in glioblastoma patients.     

DNA methylation changes in ex-adenoma carcinoma of the large intestine

Ex-adenoma carcinoma (EAC) is a carcinoma with contiguous adenoma element in its vicinity which provides a morphological evidence for adenoma–carcinoma sequence. During multistep colorectal carcinogenesis, promoter CpG island hypermethylation has been known to increase in a stepwise manner whereas diffuse genomic hypomethylation has been known to be an early event and not progress. However, some controversies exist. EAC is a good model to study the timing of hypermethylation and hypomethylation changes during multistep carcinogenesis, which this study aimed to elucidate. We analyzed 39 cases of EAC for their methylation status in eight DNA methylation markers of CpG island methylator phenotype (CIMP) panel, ten CIMP-nonrelated, cancer-specific markers, and three repetitive DNA elements (ALU, LINE-1, and SAT2) using MethyLight assay or combined bisulfite restriction analysis. Twenty-two cases of cancers had contiguous tubulovillous adenomas and 17 cases had contiguous tubular adenomas. Regardless of CIMP markers or nonrelated markers, a significant increase in the number of methylated genes was found from normal mucosa to adenoma, whereas no increase was found from adenoma to carcinoma. Both ALU and LINE-1 showed a significant decrease of methylation levels from normal mucosa to adenoma (p < 0.05), but there is no difference between adenoma and cancer. However, SAT2 methylation level exhibited a stepwise decrease from normal mucosa to adenoma to cancer. Our findings suggest that morphological progression from traditional adenoma to carcinoma does not appear to be accompanied by increases in promoter CpG island hypermethylation or repetitive DNA hypomethylation, except for SAT2 hypomethylation which showed continuous progression during multistep carcinogenesis.     

启动子DNA甲基化调节胃癌中PDX1基因表达

目的明确PDXl启动子DNA甲基化,探讨启动子甲基化对PDXl在胃癌中表达的调节作用。方法收集3例胃癌活检组织,免疫组化检测PDXl蛋白表达：吉西他滨处理3株胃癌细胞,RT—PCR检测不同药物剂量和作用时间下PDXlmRNA表达;构建PDXl报告基因,检测启动子活性及吉西他滨处理前后启动子活性的变化;甲基化特异性PCR（MSP）检测3株胃癌细胞和8对配对胃癌组织中PDXl启动子甲基化状态。结果免疫组化结果显示胃癌中PDXl表达低于正常胃黏膜;RT—PCR显示吉西他滨使PDXlmRNA重获表达,且随剂量和时间依赖性。F383有最强启动子活性,吉西他滨显著增加了PDXl启动子活性（P〈0．05）。F383在AGS、BCG823、SGC7901中呈DNA完全甲基化状态;87．5％的胃癌组织出现F383部分甲基化,12．5％出现完全甲基化。癌旁正常组织仅有37．5％出现F383部分甲基化,未出现完全甲基化,两者比较有显著性差异（P〈0．05）。结论PDXl启动子存在DNA高甲基化,抑制了胃癌中PDXl的表达。     

The contribution of LFA-1 (CD11a/CD18) and MAC-1 (CD11b/CD18) to the in vivo migration of polymorphonuclear leucocytes to inflammatory reactions in the rat.

Recently the critical requirement for the CD18 family of adhesion molecules on leucocytes for their adhesion and migration to inflammatory reactions has been recognized in humans and several animal models. The in vivo studies have mostly utilized antibodies to CD18, the common beta-subunit of CD11a,b,c/CD18 molecules and thus have blocked the function of all three family members, making evaluation of the role of individual subunits impossible. Furthermore, none of the reagents used were suitable for studies in rats. Here we report the effects on polymorphonuclear leucocyte (PMNL) adhesion and in vivo migration of a new monoclonal antibody (mAb) TA3, which recognizes and blocks rat CD11a/CD18 (LFA-1). These studies also evaluated mAb MRC OX42, which reacts with rat CD11b/CD18 (CR3, MAC-1). Neither antibody alone inhibited rat PMNL adhesion to interleukin-1 (IL-1)-activated rat endothelium, but the combination inhibited adhesion by 44%. OX42 treatment of rat PMNL inhibited phorbol myristate acetate (PMA) activated adhesion by 88%, while TA3 only inhibited this adhesion in combination with OX42, resulting in 99% inhibition of PMA-induced PMNL adhesion. Treatment of rats with TA3 alone partially inhibited 51Cr-labelled rat blood PMNL migration into zymosan-activated serum (C5adesArg; ZAS), but not IL-1, or endotoxin [lipopolysaccharide (LPS)] induced dermal inflammatory reactions. MAb OX42 had no such effect in vivo. However, treatment with both antibodies virtually eliminated any PMNL accumulation in all three types of inflammatory reactions. Ex vivo treatment of the 51Cr-labelled PMNL, prior to i.v. infusion showed that mAb TA3 again preferentially inhibited PMNL migration to ZAS. These results suggest that in the rat, CD11a/CD18 plays a major role in PMNL migration to C5a and that either CD11a or CD11b/CD18 can function to maintain normal PMNL migration to IL-1 or LPS dermal inflammatory reactions. More than one member of this adhesion family or their ligands may need to be targeted for effective modulation of PMNL infiltration, at least in this species.     

Blocking ICAM-1 (CD54) and LFA-1 (CD11a) inhibits experimental allergic conjunctivitis.

Cell adhesion molecules are critical for the homing and migration of leukocytes into inflamed tissues. We investigated the role of ICAM-1 and LFA-1 in a previously described experimental model of ragweed (Rw)-induced allergic conjunctivitis. SWR/J mice were treated intraperitoneally 6 and 1 h prior to topical challenge with Rw with injections of anti-ICAM-1 monoclonal antibody (mAb), anti-LFA-1 mAb, both anti-ICAM-1 and anti-LFA-mAbs, or rat IgG. Blocking ICAM-1 or LFA-1 reduced the clinical signs of allergic conjunctivitis. Treatment with anti-ICAM-1 or anti-LFA-1 mAbs also significantly inhibited cellular infiltration into the conjunctiva. The greatest inhibitory effect was achieved with the combination of antibodies against both cell adhesion molecules. Since antibodies against ICAM-1 and LFA-1 significantly inhibit the development of the clinical and histologic signs of allergic conjunctivitis, they may be useful for treating patients with ocular allergy.     

急性白血病p53基因P1启动子区域DNA甲基化研究

目的：通过检测急性白血病（AL）中p53基因P1启动子异常甲基化，探讨p53基因异常甲基化在急性白血病中的意义。方法:分别使用限制性内切酶MspⅠ、HpaⅡ、EcoRⅡ、BstNⅠ酶切提取基因组DNA，然后分别使用酶切后产物及基因组DNA为模板进行PCR扩增。产物电泳后在凝胶成像分析系统内观测电泳条带及摄像；部分标本的电泳条带经凝胶回收纯化后进行测序。结果:急性白血病患者p53基因第一启动子甲基化阳性率为38.7％，而急性淋巴细胞白血病（ALL）与急性非淋巴细胞白血病(ANLL)患者分别为45.5％、35.0％。正常对照标本中未检测到p53基因的异常甲基化。p53基因甲基化情况在急性白血病病人与正常人之间经过统计学检验，P<0.05；但急性淋巴细胞白血病与急性非淋巴细胞白血病患者之间无显著差异，P>0.05。分析急性白血病患者p53基因甲基化与患者临床资料之间的关系，其中，p53基因异常甲基化与肝脾淋巴结是否肿大之间的关系经统计学分析P<0.05。结论:①部分急性白血病患者存在p53基因第一启动子异常甲基化，正常对照中未检测到p53基因的甲基化；②p53基因第一启动子在急性淋巴细胞白血病与急性非淋巴细胞白血病均可发生异常甲基化，两者之间发生甲基化的概率无统计学差异；③p53基因异常甲基化与肝脾淋巴结肿大有显著差异，但p53基因异常甲基化与急性白血病治疗效果及预后的关系尚不能确定，须进一步研究确定。     

CR3 (CD11b/CD18) and CR4 (CD11c/CD18) are involved in complement-independent antibody-mediated phagocytosis of Cryptococcus neoformans

IgM and IgA to the Cryptococcus neoformans capsular glucuronoxylomannan (GXM) promote complement-independent phagocytosis by macrophages with efficiency comparable to that of IgG1. IgM- and IgA-mediated phagocytosis of C. neoformans was proportional to CR3 expression, inhibited by Abs to CR3 (CD11b/CD18) and CR4 (CD11c/CD18), and dramatically reduced with macrophages of CD18-deficient mice. IgM and IgA promoted ingestion of yeast cells by CHO cells expressing CR3 and CR4. In contrast, IgG1-mediated phagocytosis was only partially inhibited by Abs to CR3 and CR4. Phagocytosis by IgM and IgA but not IgG1 was inhibited by soluble GXM, which binds CD18. Involvement of CR in antibody-mediated complement-independent phagocytosis indicates a new link between innate and adaptive immune systems.     

Participation of CR1 (CD35), CR3 (CD11b/CD18) and CR4 (CD11c/CD18) in membranoproliferative glomerulonephritis type I.

Intraglomerular expression of complement receptors (CR) was investigated chronologically in 22 repeatedly biopsied patients with membranoproliferative glomerulonephritis (MPGN) type I by indirect immunoperoxidase staining using MoAbs. Patients were divided into two groups based on whether intraglomerular C3c deposition was decreased at the second biopsy (2nd Bx) (group A, n = 12), or not (group B, n = 10). At the first biopsy (1st Bx), the severity of glomerular injury and the degree of glomerular C3c deposition were compatible between the two groups. Four patterns of CR1 (CD35) expression on podocytes were recognized: normal; generally decreased; focally/segmentally lost; and completely lost. The numbers of CR3 (CD11b/CD18)- and CR4 (CD11c/CD18)-positive cells per glomerular cross-section were counted. At the 1st Bx, no significant difference was found in the number of CR3+ or CR4+ cells between the two groups. At the 2nd Bx, the numbers of both the CR3+ and CR4+ cells were significantly decreased only in group A (P < 0.01). The numbers of CR3+ and CR4+ cells were significantly higher in cases with moderate or marked C3c deposits than in those with no or mild C3c deposits. The intensity of CR1 expression in group B was less than that in group A at both the 1st and 2nd Bx (1st, P < 0.05; 2nd, P < 0.01), and chronological improvement of CR1 expression was observed only in group A. The severity of glomerular injury was increased only in group B (P < 0.01), and was associated with persistent massive proteinuria and hypocomplementaemia. Our results suggest that, in cases with an adverse outcome, a more severe defect of CR1 initially exists and the expression of CR1 is not recoverable chronologically. This irreversible decrease or loss of CR1 may partly contribute to the continuous C3c deposition and intraglomerular infiltration of CR3+ and CR4+ cells.     

Age-dependent changes in DNA polymerase fidelity and proofreading activity during cellular aging.

DNA polymerase alpha and the 3'-->5' exonuclease involved in the proofreading of DNA synthesis were isolated from human diploid fetal lung fibroblast (TIG-1) cells at various population doubling levels (PDL). The final PDL of the TIG-1 cells used in these experiments was 70. The fidelity of DNA polymerase alpha remained high until late passage and fell suddenly just before the end of the life span between 65 and 69 PDL. The activities of the 3'-->5' exonuclease related to proofreading remained unchanged from 21 to 61 PDL, but the activity decreased rapidly in more aged cells. The 3'-->5' exonuclease activity at 69 PDL was about 50% of that in TIG cells at 21 PDL. In vitro DNA synthesis by DNA polymerase alpha from TIG-1 cells harvested at 69 PDL showed the amount of non-complementary nucleotides incorporated to be decreased by the addition of the 3'-->5' exonuclease from the same cells. However, not all errors were edited out since the ratio of DNA polymerase activity to 3'-->5' exonuclease activity was adjusted to reflect that in vivo and the infidelity of DNA synthesis by error-prone DNA polymerase alpha from aged cells was improved by the addition of the highly active 3'-->5' exonuclease from cells at 41 PDL. These results suggested that the mutation frequency rises just before the end of the life span of TIG-1 cells.     

Obesity related methylation changes in DNA of peripheral blood leukocytes

Background

Oncogenic point mutations in KIT or PDGFRA are recognized as the primary events responsible for the pathogenesis of most gastrointestinal stromal tumors (GIST), but additional genomic alterations are frequent and presumably required for tumor progression. The relative contribution of such alterations for the biology and clinical behavior of GIST, however, remains elusive.

Methods

In the present study, somatic mutations in KIT and PDGFRA were evaluated by direct sequencing analysis in a consecutive series of 80 GIST patients. For a subset of 29 tumors, comparative genomic hybridization was additionally used to screen for chromosome copy number aberrations. Genotype and genomic findings were cross-tabulated and compared with available clinical and follow-up data.

Results

We report an overall mutation frequency of 87.5%, with 76.25% of the tumors showing alterations in KIT and 11.25% in PDGFRA. Secondary KIT mutations were additionally found in two of four samples obtained after imatinib treatment. Chromosomal imbalances were detected in 25 out of 29 tumors (86%), namely losses at 14q (88% of abnormal cases), 22q (44%), 1p (44%), and 15q (36%), and gains at 1q (16%) and 12q (20%). In addition to clinico-pathological high-risk groups, patients with KIT mutations, genomic complexity, genomic gains and deletions at either 1p or 22q showed a significantly shorter disease-free survival. Furthermore, genomic complexity was the best predictor of disease progression in multivariate analysis.

Conclusions

In addition to KIT/PDGFRA mutational status, our findings indicate that secondary chromosomal changes contribute significantly to tumor development and progression of GIST and that genomic complexity carries independent prognostic value that complements clinico-pathological and genotype information.     

整合素CD11a、CD11b和CD11c在大鼠心脏发育中的表达变化

目的 探讨整合素CD11a、CD11b和CD11c在大鼠心脏发育中的表达变化。方法 利用免疫组织化学和RT-PCR方法,检测胚胎18d(E18d)、生后5d(P5d)、P19d、P40d及生后1年（P1y）大鼠心肌组织的CD11a、CD11b和CD11c的基因和蛋白表达。结果 免疫组织化学结果显示,大鼠心肌
组织CD11a、CD11b和CD11c表达部位在心肌细胞质内;从E18d到P1y大鼠心肌组织CD11a、CD11b和CD11c的表达逐渐减弱。 RT-PCR显示,CD11a、CD11b、CD11c各组均呈阳性表达。其中CD11a在P5d和P40d间,P5d和 P19d间比较（P>0.05）差异无统计学意义,其他各组间比较差异均有统计
学意义;CD11b在E18d、P5d、P19d和P40d分别比较（P>0.05）差异无统计学意义,其他各组差异均有统计学意义;CD11c各组间差异有统计学意义（P<0.01）。结论 CD11a、CD11b和CD11c在大鼠心肌的发育过程中出现表达量的变化,不同结构的整合素分子在心脏发育过程表现出相似的
表达规律,它们可能对心肌细胞的发育起重要的调控作用。