Fine-tuning cell organelle dynamics during mitosis by small GTPases / 医学前沿

During mitosis, the allocation of genetic material concurs with organelle transformation and distribution. The coordination of genetic material inheritance with organelle dynamics directs accurate mitotic progression, cell fate determination, and organismal homeostasis. Small GTPases belonging to the Ras superfamily regulate various cell organelles during division. Being the key regulators of membrane dynamics, the dysregulation of small GTPases is widely associated with cell organelle disruption in neoplastic and non-neoplastic diseases, such as cancer and Alzheimer's disease. Recent discoveries shed light on the molecular properties of small GTPases as sophisticated modulators of a remarkably complex and perfect adaptors for rapid structure reformation. This review collects current knowledge on small GTPases in the regulation of cell organelles during mitosis and highlights the mediator role of small GTPase in transducing cell cycle signaling to organelle dynamics during mitosis.

Methylation-Based Age Estimation Model Construction and Its Effectiveness Evaluation / 法医学杂志

OBJECTIVES@#To screen the DNA methylation loci associated with the age of Han males in northern China and to construct an age estimation model.@*METHODS@#Twenty-one candidate methylation loci were screened. The DNA methylation levels of 476 blood samples from Chinese Han males were detected for 21 amplicons using EpiTYPER technology platform, and data on 153 DNA methylation loci were obtained.@*RESULTS@#After correlation analysis, 8 age-related DNA methylation loci were finally screened. CpG1, CpG2, CpG4, CpG7, CpG8 were located on TRIM59, RASSF5, Clorf132, CSNK1D, ELOVL2,CpG5, CpG6 on PDE4C, and CpG3 on chr17:21452808. Based on the 8 loci, 352 samples were used for model construction. A multivariate linear regression age estimation model was constructed （R2=0.93）, with mean absolute deviation （MAD） of 2.69 years old. When 109 samples were used for model validation, the MAD was 3.80 years old. The test was repeated 3 times in 15 new samples, with MADs of 4.08, 4.68 and 3.93 years old, respectively.@*CONCLUSIONS@#The age estimation model on Han males in northern China constructed in this study can be used to estimate the age of victims and suspects and to narrow the scope of investigation, and therefore has practical application value.

The role of the exocyst in renal ciliogenesis, cystogenesis, tubulogenesis, and development

The exocyst is a highly conserved eight-subunit protein complex (EXOC1–8) involved in the targeting and docking of exocytic vesicles translocating from the trans-Golgi network to various sites in renal cells. EXOC5 is a central exocyst component because it connects EXOC6, bound to the vesicles exiting the trans-Golgi network via the small GTPase RAB8, to the rest of the exocyst complex at the plasma membrane. In the kidney, the exocyst complex is involved in primary ciliognesis, cystogenesis, and tubulogenesis. The exocyst, and its regulators, have also been found in urinary extracellular vesicles, and may be centrally involved in urocrine signaling and repair following acute kidney injury. The exocyst is centrally involved in the development of other organs, including the eye, ear, and heart. The exocyst is regulated by many different small GTPases of the RHO, RAL, RAB, and ARF families. The small GTPases, and their guanine nucleotide exchange factors and GTPase-activating proteins, likely give the exocyst specificity of function. The recent development of a floxed Exoc5 mouse line will aid researchers in studying the role of the exocyst in multiple cells and organ types by allowing for tissue-specific knockout, in conjunction with Cre-driver mouse lines.

Mass spectrometry based proteomics profiling of human monocytes

Human monocyte is an important cell type which is involved in various complex human diseases. To better understand the biology of human monocytes and facilitate further studies, we developed the first comprehensive proteome knowledge base specifically for human monocytes by integrating both in vivo and in vitro datasets. The top 2000 expressed genes from in vitro datasets and 779 genes from in vivo experiments were integrated into this study. Altogether, a total of 2237 unique monocyte-expressed genes were cataloged. Biological functions of these monocyte-expressed genes were annotated and classified via Gene Ontology (GO) analysis. Furthermore, by extracting the overlapped genes from in vivo and in vitro datasets, a core gene list including 541 unique genes was generated. Based on the core gene list, further gene-disease associations, pathway and network analyses were performed. Data analyses based on multiple bioinformatics tools produced a large body of biologically meaningful information, and revealed a number of genes such as SAMHD1, G6PD, GPD2 and ENO1, which have been reported to be related to immune response, blood biology, bone remodeling, and cancer respectively. As a unique resource, this study can serve as a reference map for future in-depth research on monocytes biology and monocyte-involved human diseases.

Role of Rheb in Human Acute Myeloid Leukemia / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the role of Rheb (mTOR activator) in AML development by measuring Rheb expression in bone marrow of adult AML patients and in AML cell line HL-60.</p><p><b>METHODS</b>Real-time PCR assay was used to measure the Rheb mRNA expression in 27 AML patients and 29 ITP patients as control. The relationship between Rheb mRNA expression and age, AML subtype, fusion gene, splenomegaly, hepatomegaly and survival of AML patients was analyzed and compared. In addition, HL-60 cell line over-expressing Rheb was established, and the HL-60 cells and HL-60 cells with overexpression of Rheb were treated with Ara-C of different concentrations, the proliferation level was detected by CCK-8 method, and the IC50 was calculated.</p><p><b>RESULTS</b>The mRNA level of Rheb in AML patients was similar to that in ITP patients (control). Interestingly, higher expression of Rheb was associated with better survival and was sensitive to Ara-C treatment. However, the expression level of Rheb was not associated with age, AML subtype, fusion gene, and hepatomegaly of patients. Lower expression level of Rheb was associated with splenomegaly. In vitro analysis of HL-60 line indicated that overexpression of Rheb could increased the cell sensitivity to Ara-C treatment (IC50=0.54 µmol/L) and caused HL-60 cell apoptosis.</p><p><b>CONCLUSION</b>The lower Rheb expression is a poor prognostic indicator for AML patients, which is associated with AML splenomegaly, the patients and HL-60 cells with low expression of Rheb are insensitive to Ara-C treatment.</p>

N-acetylcysteine and the human serum components that inhibit bacterial invasion of gingival epithelial cells prevent experimental periodontitis in mice

PURPOSE: We previously reported that human serum significantly reduces the invasion of various oral bacterial species into gingival epithelial cells in vitro. The aims of the present study were to characterize the serum component(s) responsible for the inhibition of bacterial invasion of epithelial cells and to examine their effect on periodontitis induced in mice. METHODS: Immortalized human gingival epithelial (HOK-16B) cells were infected with various 5- (and 6-) carboxy-fluorescein diacetate succinimidyl ester-labeled oral bacteria, including Fusobacterium nucleatum, Provetella intermedia, Porphyromonas gingivalis, and Treponiema denticola, in the absence or presence of three major serum components (human serum albumin [HSA], pooled human IgG [phIgG] and alpha1-antitrypsin). Bacterial adhesion and invasion were determined by flow cytometry. The levels of intracellular reactive oxygen species (ROS) and activation of small GTPases were examined. Experimental periodontitis was induced by oral inoculation of P. gingivalis and T. denticola in Balb/c mice. RESULTS: HSA and phIgG, but not alpha1-antitrypsin, efficiently inhibited the invasion of various oral bacterial species into HOK-16B cells. HSA but not phIgG decreased the adhesion of F. nucleatum onto host cells and the levels of intracellular ROS in HOK-16B cells. N-acetylcysteine (NAC), a ROS scavenger, decreased both the levels of intracellular ROS and invasion of F. nucleatum into HOK-16B cells, confirming the role of ROS in bacterial invasion. Infection with F. nucleatum activated Rac1, a regulator of actin cytoskeleton dynamics. Not only HSA and NAC but also phIgG decreased the F. nucleatum-induced activation of Rac1. Furthermore, both HSA plus phIgG and NAC significantly reduced the alveolar bone loss in the experimental periodontitis induced by P. gingivalis and T. denticola in mice. CONCLUSIONS: NAC and the serum components HSA and phIgG, which inhibit bacterial invasion of oral epithelial cells in vitro, can successfully prevent experimental periodontitis.

Tactics used by HIV-1 to evade host innate, adaptive, and intrinsic immunities / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To review the mechanisms by which HIV evades different components of the host immune system.</p><p><b>DATA SOURCES</b>This review is based on data obtained from published articles from 1991 to 2012. To perform the PubMed literature search, the following key words were input: HIV and immune evasion.</p><p><b>STUDY SELECTION</b>Articles containing information related to HIV immune evasion were selected.</p><p><b>RESULTS</b>Although HIV is able to induce vigorous antiviral immune responses, viral replication cannot be fully controlled, and neither pre-existing infected cells nor latent HIV infection can be completely eradicated. Like many other enveloped viruses, HIV can escape recognition by the innate and adaptive immune systems. Recent findings have demonstrated that HIV can also successfully evade host restriction factors, the components of intrinsic immune system, such as APOBEC3G (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G), TRIM5α (tripartite motif 5-α), tetherin, and SAMHD1 (SAM-domain HD-domain containing protein).</p><p><b>CONCLUSIONS</b>HIV immune evasion plays an important role in HIV pathogenesis. Fully understanding the tactics deployed by HIV to evade various components of the host immune systems will allow for the development of novel strategies aimed toward the prevention and cure of HIV/AIDS.</p>

Effects of Rheb overexpression in HL-60 and K562 leukemia cell lines / 中国实验血液学杂志

mTOR (mammalian target of rapamycin) is the center for cellular activities. It controls many cell activities via inhibiting apoptosis and promoting cell growth. Rheb can activate mTOR signaling pathway and participate in genesis and development of multiple cancers. This study was purposed to explore the underlying role of Rheb in human myeloid leukemia by using the myeloid leukemia cell lines. Two myeloid leukemia cell lines HL-60 and K562 overexpressing Rheb were established with retrovirus containing Rheb. The mRNA and protein expressions of Rheb were determined by Real-Time PCR and Western blot respectively. Cell proliferation rate was examined by CCK-8 assay and apoptosis rate was analyzed using Annexin V and 7-AAD double-staining. The results showed that Rheb was overexpressed in both HL-60 and K562 cell lines. The Rheb overexpression cell lines were successfully established. It is found that overexpression of Rheb could promote cell growth. Furthermore, the overexpression of Rheb could accelerate cells entering into G2/M phase (P < 0.01), while did not affect the apoptosis. It is concluded that Rheb overexpression promotes myeloid leukemia cell proliferation through accelerating cell cycle progression.

Research progress of the anti-HIV activity of SAMHD1 / 病毒学报

The SAM and HD domain containing protein 1 (Sterile alpha motif domain and HD domain-containing protein 1, SAMHD1) is a putative negative regulator of the antiviral innate immune response. It can significantly increase the antiviral immune response, mediates the interferon-induced inflammatory response involved in the host foreign-virus defense system. The early studies have focused on its gene mutations associated with Aicardi-Goutières syndrome (AGS), the latest study found that SAMHD1 as a potent dGTP-stimulated triphosphohydrolase restricts HIV-1 replication by hydrolyzing the majority of cellular dNTPs, thus inhibiting reverse transcription and viral complementary DNA (cDNA) synthesis. Auxiliary gene of HIV-2 and simian immunodeficiency virus (SIVsm / mac) encoding the Vpx protein can eliminate HIV-1 restriction. In recent years, the research on SAMHD1, mores forward rapidly this paper overviews the recent research progression related to the above fields.

Construction of recombinant lentiviral vectors containing Rheb gene and its mutant Rheb'D60K gene and their expression in human liver cancer cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct recombinant lentiviral vectors carrying Rheb gene and its mutant Rheb'D60K gene, and examine their expression in human liver cancer cells.</p><p><b>METHODS</b>Rheb gene was amplified by PCR to construct the recombinant plasmid LV31-Rheb-WT and LV31-Rheb-D60K. HEK-293 FT cells were contransfected with the recombinant lentiviral vector together with a lentiviral package plasmid to produce the lentiviral particles. The expression of PS6 protein was detected in the lentivirus-infected MCF-7 cells. The apoptosis of SK-HEP-1 cells transfected with LV31-Rheb-WT or LV31-Rheb-D60K was observed.</p><p><b>RESULTS</b>The recombinant LV31-Rheb-WT and LV31-Rheb-D60K vectors were confirmed by PCR and DNA sequencing. Western blotting showed that PS6 protein expression was increased in LV31-Rheb-WT-transfected cells while decreased in LV31-Rheb-D60K-transfected cells. LV31-Rheb-D60K-transfected SK-HEP-1 cells showed more obvious apoptosis after starvation than LV31-Rheb-WT-transfected cells.</p><p><b>CONCLUSION</b>Lentiviral vectors carrying Rheb gene and its mutant has been successfully constructed, which can be useful in further investigation of the role of Rheb gene in cancer cells.</p>

p21-Activated Kinases (PAKs) as a Therapeutic Target / 대한이비인후과학회지

p21-activated kinases (PAKs) are a family of serine/threonine protein kinases comprised of six isoform (PAK1-6), all of which are direct targets of the small GTPases Rac and Cdc42. PAKs have recently been shown to regulate various cellular activities, including cell motility, survival and proliferation, the organization and function of cytoskeleton and extracellular matrix, transcription and translation. PAKs are overexpressed or hyperactivated in several human tumor, such as breast cancer, gastric cancer, ovarian cancer etc., which makes them an attractive new therapeutic targets. Thus, there has been considerable interest in the development of inhibitors to the PAKs, as biological markers and leads for the development of therapeutics.

Small GTPases and formins in mammalian oocyte maturation: cytoskeletal organizers / 대한생식의학회지

The maturation process of mammalian oocytes accompanies an extensive rearrangement of the cytoskeleton and associated proteins. As this process requires a delicate interplay between the cytoskeleton and its regulators, it is often targeted by various external and internal adversaries that affect the congression and/or segregation of chromosomes. Asymmetric cell division in oocytes also requires specific regulators of the cytoskeleton, including formin-2 and small GTPases. Recent literature providing clues regarding how actin filaments and microtubules interact during spindle migration in mouse oocytes are highlighted in this review.

Characterization of the Rho GTPase-Activating Protein RhoGAP68F

Rho small GTPases control multiple aspects of neuronal morphogenesis by regulating the assembly and organization of the actin cytoskeleton. Although they are negatively regulated by GTPase activating proteins (GAPs), the roles of RhoGAPs in the nervous system have not been fully investigated. Here we describe a characterization of Drosophila RhoGAP68F that is mainly expressed in the embryonic central nervous system. RNA in situ hybridization analysis showed that expression of RhoGAP68F is highly restricted to the embryonic brain and ventral nerve cord. Database search revealed that RhoGAP68F contains an N-terminal Sec14 domain and a C-terminal RhoGAP domain. Rho-GTP pull-down assay demonstrated that the RhoGAP domain of RhoGAP68F inactivates RhoA but not Rac1 or Cdc42 in HEK293 cells. In addition, expression of RhoGAP68F in NIH3T3 cells suppressed LPA-induced stress fiber formation, which is mediated by RhoA. Finally, neuronal overexpression of RhoGAP68F causes synaptic overgrowth at the larval neuromuscular junction (NMJ). Taken together, these results suggest that RhoGAP68F may play a role in synaptic growth regulation by inactivating RhoA.

Overview of the Renin-Angiotensin System

Angiotensin II is an octapeptide hormone of the renin-angiotensin system (RAS), and it regulates a wide variety of physiological responses including salt and water balance, the blood pressure and the vascular tone. Clinical trials with angiotensin-converting enzyme (ACE) inhibitors have demonstrated survival benefits in subjects with congestive heart failure and myocardial infarction, and this support the importance of angiotensin II in the pathogenesis of cardiovascular diseases. Through activation of small G proteins such as Ras, Rho, and Rac, angiotensin II induces remodeling of vascular smooth muscle cells (VSMC), including proliferation, migration, hypertrophy and inflammation. Angiotensin (1-7) appears to be the main effector peptide of ACE2 with vasodilatory, natriuretic and antiinflammatory properties. The cross-talk between the angiotensin II receptors may play an important role in maintaining cardiovascular homeostasis.

Molecular characterization of GTP binding protein gene in dermatophyte pathogen trichophyton rubrum

Trichophyton rubrum [T. rubrum] is an anthropophilic dermatophyte that is distributed worldwide and causes common cutaneous disease such as mycosis. Although several properties of this fungus have been investigated so far, however a few studies were carried out in the field of molecular biology of this fungus. In the present study we tried to identify its molecular characterization of the goanosin three phosphat [GTP] binding protein gene. Pairs of 21 nt primers were designed from highly conserved regions of the gene in other fungi. The primers were utilized in PCR by using isolated genomic DNA tem-plate as well as cytoplasmic RNA of T. rubrum and the PCR and RT-PCR fragments were then sequenced. About 645 nucleotides have been sequenced which encodes a polypeptide with 214 amino acids. Nucleotide sequence comparison in gene data banks [NCBI, NIH] for both the DNA and its deduced amino acid sequence revealed significant homology with GTP binding protein genes and proteins of other eukaryotic cells. The amino acid sequence of the encoded protein was about 64% identical to the sequence of GTP binding protein from other fungi. In summary, we have cloned the first GTP binding protein of dermatophytes and characterized it as a member of this gene family in other eukaryotic cells

The association of the expression of MTA1, nm23H1 with the invasion, metastasis of ovarian carcinoma / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To understanding the molecular mechanisms in invasion and metastasis of the ovarian carcinoma, we investigate a novel candidate metastasis-associated gene (MTA1) and nm23H1 mRNA expression and mutation in ovarian carcinoma.</p><p><b>METHODS</b>Twenty primary ovarian carcinoma specimens, 20 corresponding lymph nodes and 8 normal ovarian was examined for mRNA expression and mutation of MTA1 and nm23H1 genes by reverse-transcription polymerase chain reaction (RT-PCR) and RT-PCR-SSCP analysis. The level of the expression was determined by the relative optic density (ROD) of the PCR products.</p><p><b>RESULTS</b>The frequency of MAT1 overexpression was 100% (7/7) in primary ovarian carcinoma with metastasis but only 38.5% (5/13) in those without metastasis (P=0.0103). Overexpression of MAT1 was observed in 87.5% (6/7) of lymph nodes with metastasis but only 23% (3/13) of lymph nodes without metastasis (P=0.0118). In contrast with MAT1, low expression of nm23H1 mRNA was seen in 7 of 7 ovarian carcinoma with metastasis but only in 4 of 13 (30%) of those without metastasis (P=0.0043). Low nm23H1 expression was also seen in 7 of 7 lymph nodes with metastasis but only in 5 of 13 (38.5%) nonmetastatic lymph nodes (P=0.0102). The ROD ratio of MAT1 to nm23H1 increased with the development of metastasis. No mutation of MAT1 and nm23H1 genes was found by SSCP analysis.</p><p><b>CONCLUSION</b>The mRNA expression of MTA1 and nm23H1 is positively and negatively correlated with lymph node metastasis, respectively. Expression abnormalities but not mutation of the two genes are frequent events related to lymph node metastasis of ovarian cancer.</p>

Transfection of the nm23-H1 gene into BcaCD885 cell line inhibits the potential of invasion, adhesion and mobility / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To transfect nm23-H1 into the BcaCD885 cell lines in order to get safe high-efficiency and low-toxicity, and to find out whether nm23-H1 could affect the invasion and metastases ability of BcaCD885 cell lines.</p><p><b>METHODS</b>Lipofect was used to transfect nm23-H1 into BcaCD885 cell lines; immunohistochemistry was used to detect the difference expression of nm23-H1 between transfected and non-transfected cell lines; then transwell-room and wash way were used to detect the difference of invasion and metastases ability between transfected and non-transfected cell lines.</p><p><b>RESULTS</b>PCMV-NEO-BAM system gave the stability expression of nm23-H1; there was significant different NDPKA expression between transfected and non-transfected BcaCD885 cell lines; the invasion and metastases ability of transfected BcaCD885 cell lines decreased obviously.</p><p><b>CONCLUSION</b>nm23-H1 can inhibit the metastases of BcaCD885 cell lines significantly.</p>

The effects of conjugated linoleic acid on the expression of invasiveness and metastasis-associated gene of human gastric carcinoma cell line / 中华预防医学杂志

<p><b>OBJECTIVES</b>To study the effects of c9,t11-conjugated linoleic acid (c9,t11-CLA) on invasive ability of human gastric carcinoma cell line (SGC-7901) and to explore its possible mechanism.</p><p><b>METHODS</b>Reconstituted basement membrane invasion assay was used to evaluate invasive ability of cancer cells. Expression of TIMP-1, TIMP-2 and nm23-H(1) mRNA was measured by reverse transcription polymerase chain reaction (RT-PCR) in SGC-7901 cells.</p><p><b>RESULTS</b>At the concentrations of 200 micromol/L, 100 micromol/L and 50 micromol/L, c9,t11-CLA suppressed their reconstituted basement membrane invasion of SGC-7901 by 53.7%, 40.9% and 29.3%, respectively. c9,t11-CLA could induce the expression of TIMP-1, TIMP-2 and nm23-H(1) mRNA in SGC-7901 cells.</p><p><b>CONCLUSIONS</b>The invasion of SGC-7901 cells could be inhibited by c9,t11-CLA through reconstituted basement membrane. Anti-invasion action of c9,t11-CLA might be associated with induction of expression of TIMP-1, TIMP-2 and nm23-H(1) mRNA in tumor cells.</p>

Angiogenesis and the expression of nm23-H(1) tumor metastatic suppressor gene in primary breast carcinoma and their relations to lymph node metastasis / 中华外科杂志

<p><b>OBJECTIVE</b>To study angiogenesis and the expression of nm23-H(1) tumor metastatic suppressor gene in primary breast carcinoma and their relationship with axillary lymph node metastasis.</p><p><b>METHODS</b>Intratumoral vascularization in 80 cases of breast cancer was observed preoperatively by power doppler imaging (PDI) and analysed with computer-assisted quantative assessment, and the expression of microvessel density (MVD) and nm23 protein was determined by immunohistochemical technique.</p><p><b>RESULTS</b>Blood flow signals and blood vessels postitive area within masses were more in axillary node positive (LN+) group than in axillary node negative (LN-) group (t = 7.07, P < 0.01), MVD expression were higher in the LN+ group than in the LN- group (t = 6.34, P < 0.01). Meanwhile the expression of nm23-H(1) protein was lower in the LN+ group than in the LN- group, and significant correlation was found between angiogenesis and the expression of nm23-H(1) protein.</p><p><b>CONCLUSIONS</b>Angiogenesis and the expression of nm23-H(1) protein may play an important role in the lymphatic metastasis process of breast cancer. Furthermore, angiogenesis may correlates with the expression of nm23-H(1) protein in that progress.</p>

Phosphorylation of 46-kappa Da protein of synaptic vesicle membranes is stimulated by GTP and Ca2+/calmodulin

The release of neurotransmitter is regulated in the processes of membrane docking and membrane fusion between synaptic vesicles and presynaptic plasma membranes. Synaptic vesicles contain a diverse set of proteins that participate in these processes. Small GTP-binding proteins exist in the synaptic vesicles and are suggested to play roles for the regulation of neurotransmitter release. We have examined a possible role of GTP-binding proteins in the regulation of protein phosphorylation in the synaptic vesicles. GTPgammaS stimulated the phosphorylation of 46 kappa Da protein (p46) with pI value of 5.0-5.2, but GDPbetaS did not. The p46 was identified as protein interacting with C-kinase 1 (PICK-1) by MALDI-TOF mass spectroscopy analysis, and anti-PICK-1 antibody recognized the p46 spot on 2-dimensional gel electrophoresis. Rab guanine nucleotide dissociation inhibitor (RabGDI), which dissociates Rab proteins from SVs, did not affect phosphorylation of p46. Ca2+/ calmodulin (CaM), which causes the small GTP- binding proteins like Rab3A and RalA to dissociate from the membranes and stimulates CaM- dependnet protein kinase(s) and phosphatase, strongly stimulate the phosphorylation of p46 in the presence of cyclosporin A and cyclophylin. However, RhoGDI, which dissociates Rho proteins from membranes, reduced the phosphorylation of p46 to the extent of about 50%. These results support that p46 was PICK-1, and its phosphorylation was stimulated by GTP and Ca2+/CaM directly or indirectly through GTP-binding protein(s) and Ca2+/CaM effector protein(s). The phosphorylation of p46 (PICK-1) by GTP and Ca2+/CaM may be important for the regulation of transporters and neurosecretion.