Latent transforming growth factor-beta-binding protein-4 regulates transforming growth factor-beta1 bioavailability for activation by fibrogenic lung fibroblasts in response to bleomycin
Zhou, Yong; Koli, Katri; Hagood, James S; Miao, Mi; Mavalli, Mahendra; Rifkin, Daniel B; Murphy-Ullrich, Joanne E
Recent evidence suggests that subsets of lung fibroblasts differentially contribute to fibrogenic progression. We have previously shown that a subset of rat lung fibroblasts with fibrogenic characteristics [Thy-1 (-) fibroblasts] responds to stimuli (bleomycin, interleukin-4, etc) with increased latent transforming growth factor (TGF)-beta activation, whereas non-fibrogenic Thy-1-expressing [Thy-1 (+)] fibroblasts do not. Activation of latent TGF-beta1 by interstitial lung fibroblasts is critical for fibrogenic responses. To better understand the susceptibility of fibrogenic fibroblasts to the stimulation of TGF-beta activation, we examined the role of latent TGF-beta-binding proteins (LTBPs), key regulators of TGF-beta bioavailability and activation, in TGF-beta1 activation by these fibroblasts. Treatment of fibroblasts with bleomycin up-regulated LTBP-4 mRNA, protein, and soluble LTBP-4-bound large latent TGF-beta1 complexes in Thy-1 (-) fibroblasts to significantly higher levels than in Thy-1 (+) fibroblasts. Bleomycin-induced TGF-beta1 activation required LTBP-4, since lung fibroblasts deficient in LTBP-4 did not activate TGF-beta1. Expression of LTBP-4 restored TGF-beta1 activation in response to bleomycin, but expression either of LTBP-4 lacking the TGF-beta-binding site or only the TGF-beta-binding domain did not. Bleomycin treatment of mice increased LTBP-4 expression in the lung. Thy-1 knockout mice had increased levels of both LTBP-4 expression and TGF-beta activation, as well as enhanced Smad3 phosphorylation compared with wild-type mice. Together, these data identify a critical role for LTBP-4 in the regulation of latent TGF-beta1 activation in bleomycin-induced lung fibrosis
PMCID:2631315
PMID: 19056849
ISSN: 1525-2191
CID: 135218
LIM kinase 1 and cofilin regulate actin filament population required for dynamin-dependent apical carrier fission from the trans-Golgi network
Salvarezza, Susana B; Deborde, Sylvie; Schreiner, Ryan; Campagne, Fabien; Kessels, Michael M; Qualmann, Britta; Caceres, Alfredo; Kreitzer, Geri; Rodriguez-Boulan, Enrique
The functions of the actin cytoskeleton in post-Golgi trafficking are still poorly understood. Here, we report the role of LIM Kinase 1 (LIMK1) and its substrate cofilin in the trafficking of apical and basolateral proteins in Madin-Darby canine kidney cells. Our data indicate that LIMK1 and cofilin organize a specialized population of actin filaments at the Golgi complex that is selectively required for the emergence of an apical cargo route to the plasma membrane (PM). Quantitative pulse-chase live imaging experiments showed that overexpression of kinase-dead LIMK1 (LIMK1-KD), or of LIMK1 small interfering RNA, or of an activated cofilin mutant (cofilin S3A), selectively slowed down the exit from the trans-Golgi network (TGN) of the apical PM marker p75-green fluorescent protein (GFP) but did not interfere with the apical PM marker glycosyl phosphatidylinositol-YFP or the basolateral PM marker neural cell adhesion molecule-GFP. High-resolution live imaging experiments of carrier formation and release by the TGN and analysis of peri-Golgi actin dynamics using photoactivatable GFP suggest a scenario in which TGN-localized LIMK1-cofilin regulate a population of actin filaments required for dynamin-syndapin-cortactin-dependent generation and/or fission of precursors to p75 transporters.
PMCID:2613098
PMID: 18987335
ISSN: 1059-1524
CID: 375192
Enhanced generation of Alzheimer's amyloid-beta following chronic exposure to phorbol ester correlates with differential effects on alpha and epsilon isozymes of protein kinase C
da Cruz e Silva, Odete A B; Rebelo, Sandra; Vieira, Sandra I; Gandy, Sam; da Cruz e Silva, Edgar F; Greengard, Paul
Alzheimer's amyloid precursor protein (APP) sorting and processing are modulated through signal transduction mechanisms regulated by protein phosphorylation. Notably, protein kinase C (PKC) appears to be an important component in signaling pathways that control APP metabolism. PKCs exist in at least 11 conventional and unconventional isoforms, and PKCalpha and PKCepsilon isoforms have been specifically implicated in controlling the generation of soluble APP and amyloid-beta (Abeta) fragments of APP, although identification of the PKC substrate phospho-state-sensitive effector proteins remains challenging. In the current study, we present evidence that chronic application of phorbol esters to cultured cells in serum-free medium is associated with several phenomena, namely: (i) PKCalpha down-regulation; (ii) PKCepsilon up-regulation; (iii) accumulation of APP and/or APP carboxyl-terminal fragments in the trans Golgi network; (iv) disappearance of fluorescence from cytoplasmic vesicles bearing a green fluorescent protein tagged form of APP; (v) insensitivity of soluble APP release following acute additional phorbol application; and (vi) elevated cellular APP mRNA levels and holoprotein, and secreted Abeta. These data indicate that, unlike acute phorbol ester application, which is accompanied by lowered Abeta generation, chronic phorbol ester treatment causes differential regulation of PKC isozymes and increased Abeta generation. These data have implications for the design of amyloid-lowering strategies based on modulating PKC activity
PMCID:2911029
PMID: 19012746
ISSN: 1471-4159
CID: 139856
Polymorphisms and splice variants influence the antiretroviral activity of human APOBEC3H
Harari, Ariana; Ooms, Marcel; Mulder, Lubbertus C F; Simon, Viviana
Human APOBEC3H belongs to the APOBEC3 family of cytidine deaminases that potently inhibit exogenous and endogenous retroviruses. The impact of single nucleotide polymorphisms (SNP) and alternative splicing on the antiretroviral activity of human APOBEC3H is currently unknown. In this study, we show that APOBEC3H transcripts derived from human peripheral blood mononuclear cells are polymorphic in sequence and subject to alternative splicing. We found that APOBEC3H variants encoding a SNP cluster (G105R, K121D and E178D, hapII-RDD) restricted human immunodeficiency virus type 1 (HIV-1) more efficiently than wild-type APOBEC3H (hapI-GKE). All APOBEC3H variants tested were resistant to HIV-1 Vif, the viral protein that efficiently counteracts APOBEC3G/3F activity. Alternative splicing of APOBEC3H was common and resulted in variants with distinct C-terminal regions and variable antiretroviral activities. Splice variants of hapI-GKE displayed a wide range of antiviral activities, whereas similar splicing events in hapII-RDD resulted in proteins that uniformly and efficiently restricted viral infectivity (>20-fold). Site-directed mutagenesis identified G105R in hapI-GKE and D121K in hapII-RDD as critical substitutions leading to an average additional 10-fold increase in antiviral activity. APOBEC3H variants were catalytically active and, similarly to APOBEC3F, favored a GA dinucleotide context. HIV-1 mutagenesis as a mode of action for APOBEC3H is suggested by the decrease of restriction observed with a cytidine deaminase domain mutant and the inverse correlation between G-to-A mutations and infectivity. Thus, the anti-HIV activity of APOBEC3H seems to be regulated by a combination of genomic variation and alternative splicing. Since prevalence of hapII-RDD is high in populations of African descent, these findings raise the possibility that some individuals may harbor effective as well as HIV-1 Vif-resistant intracellular antiviral defense mechanisms.
PMCID:2612324
PMID: 18945781
ISSN: 1098-5514
CID: 2286172
Correlating echinocandin MIC and kinetic inhibition of fks1 mutant glucan synthases for Candida albicans: implications for interpretive breakpoints
Garcia-Effron, Guillermo; Park, Steven; Perlin, David S
A detailed kinetic characterization of echinocandin inhibition was performed for mutant 1,3-beta-d-glucan synthase enzymes from clinical isolates of Candida albicans with nine different FKS1 mutations resulting in high MICs. Among 14 mutant Fks1p enzymes studied, the kinetic parameters 50% inhibitory concentration and K(i) increased 50-fold to several thousandfold relative to those for the wild type. Enzymes with mutations at Ser645 (S645P, S645Y, and S645F) within hot spot 1 showed the most prominent decrease in sensitivity, while those with mutations at the N- and C-terminal ends of hot spot 1 generally retained greater sensitivity to all three drugs. Kinetic inhibitions by caspofungin, micafungin, and anidulafungin were comparable among the fks1 mutant enzymes, although absolute values did vary with specific mutations. Amino acid substitutions in Fks1p did not alter K(m) values, although some mutations decreased the V(max). Given the association of FKS1 mutations with clinical resistance, an evaluation of the kinetic parameters for the inhibition of mutant 1,3-beta-D-glucan synthase as a function of the MIC enabled an independent evaluation of the recently adopted susceptibility breakpoint for echinocandin drugs. Overall, a breakpoint MIC of >or=2 microg/ml for caspofungin captured nearly 100% of fks1 C. albicans strains when a kinetic inhibition rise threshold of
or=0.5 microg/ml was required for >95% coverage of clinical isolates. However, when MIC determinations were performed in the presence of 50% serum, all fks1 mutants showed MIC values of >or=2 microg/ml for the three echinocandin drugs. The 1,3-beta-D-glucan synthase kinetic inhibition data support the proposed susceptibility breakpoint for caspofungin in C. albicans, but a lower susceptibility breakpoint (PMCID:2612148
PMID: 18955538
ISSN: 0066-4804
CID: 310062
A Recommended Protocol for the Immediate Postoperative Care of Lower Extremity Free-Flap Reconstructions
Rohde, Christine; Howell, Brittny Williams; Buncke, Gregory M; Gurtner, Geoffrey C; Levin, L Scott; Pu, Lee L Q; Levine, Jamie P
The success of lower extremity microsurgical reconstructions may be compromised postoperatively secondary to several factors, including thrombosis, infection, bleeding, and edema. To address edema, surgeons may use protocols for gradually dangling and/or wrapping the affected extremity. Such protocols vary widely among surgeons and are typically based on training and/or prior experience. To that end, we distributed surveys to five plastic surgeons who are experienced in microvascular lower extremity reconstruction at five different institutions. The surveys inquired about postoperative management protocols for lower extremity free flaps with regard to positioning, compression, initiation and progression of postoperative mobilization, nonweightbearing and weightbearing ambulation, assessment of flap viability, and flap success rate. These protocols were then evaluated for similarities to create a consensus of postoperative management guidelines. Progressive periods of leg dependency and compression therapy emerged as important elements. Although the consensus protocol developed in this study is considered safe by each participant, we do not intend for these recommendations to serve as a standard of care, nor do we suggest that any one particular protocol leads to improved outcomes. However, these recommendations may serve as a guide for less experienced surgeons or those without a protocol in place
PMID: 18979418
ISSN: 0743-684x
CID: 90060
Topical lineage-negative progenitor-cell therapy for diabetic wounds (invited discussion) [Letter]
Gurtner, Geoffrey C; Longaker, Michael T
PMID: 19116584
ISSN: 1529-4242
CID: 96558
IFATS Series: Adipose Stromal Cells Adopt a Proangiogenic Phenotype Under the Influence of Hypoxia
Thangarajah, Hariharan; Vial, Ivan N; Chang, Edwin; El-Ftesi, Samyra; Januszyk, Michael; Chang, Edward I; Paterno, Josemaria; Neofytou, Evgenios; Longaker, Michael T; Gurtner, Geoffrey C
Evolving evidence suggests a possible role for adipose stromal cells (ASCs) in adult neovascularization, though the specific cues that stimulate their angiogenic behavior are poorly understood. We evaluated the effect of hypoxia, a central mediator of new blood vessel development within ischemic tissue, on proneovascular ASC functions. Murine ASCs were exposed to normoxia (21% oxygen) or hypoxia (5%, 1% oxygen) for varying lengths of time. Vascular endothelial growth factor (VEGF) secretion by ASCs increased as an inverse function of oxygen tension, with progressively higher VEGF expression at 21%, 5%, and 1% oxygen, respectively. Greater VEGF levels were also associated with longer periods in culture. ASCs were able to migrate towards stromal cellderived factor-1 (SDF-1), a chemokine expressed by ischemic tissue, with hypoxia augmenting ASC expression of the SDF-1 receptor (CXCR4) and potentiating ASC migration. In vivo, ASCs demonstrated the capacity to proliferate in response to a hypoxic insult remote from their resident niche, and this was supported by in vitro studies showing increasing ASC proliferation with greater degrees of hypoxia. Hypoxia did not significantly alter the expression of endothelial surface markers by ASCs, but these cells did assume an endothelial phenotype as evidenced by their ability to tubularize in Matrigel; the presence of endothelial cells markedly increased ASC tubularization. Taken together, these data suggest that ASCs upregulate their proneovascular activity in response to hypoxia, and may harbor the capacity to home to ischemic tissue and function cooperatively with existing vasculature to promote angiogenesis. __________________________________________________________________________ ____ Author contributions: H.T.: Conception and design, collection and assembly of data, data analysis and interpretation, manuscript writing; I.N.V.: Conception and design, collection and assembly of data, data analysis and interpretation, manuscript writing; E.C.: Collection and assembly of data, data analysis and interpretation; S.El-ftesi: Collection and assembly of data, data analysis and interpretation; M.J.: Data analysis and interpretation, manuscript writing; E.I.C.: Collection and assembly of data, data analysis and interpretation; J.P.: Collection and assembly of data, data analysis and interpretation; E.N.: Collection and assembly of data, data analysis and interpretation; M.T.L.: Conception and design, data analysis and interpretation, final approval of manuscript; G.C.G.: Conception and design, financial support, data analysis and interpretation, manuscript writing, final approval of manuscript. Hariharan Thangarajah and Ivan N. Vial contributed equally to this work
PMID: 18974212
ISSN: 1549-4918
CID: 96560
[Isolation and identification of arboviruses from mosquito pools in some regions of Liaoning province, China]
Meng, Wei-Shan; Zhang, Ji-Bo; Sun, Xiao-Hong; Liu, Qi-Nan; Chen, Zhe; Zhai, You-Gang; Fu, Shi-Hong; Cao, Yu-Xi; Wang, Huan-Yu; Ding, Jun; Chu, Fa-Jun; Li, Zhi; Zhang, Li-Tian; Zhao, Yu-Jun; Liang, Guo-Dong
OBJECTIVE: To isolate and identify arboviruses from mosquito pools in some regions of Liaoning province. METHODS: Mosquitoes were collected from Shenyang, Yingkou, Panjin, Jinzhou and Dandong cities of Liaoning province in 2006. Viruses were isolated by inoculating the specimens onto C6/ 36 and BHK-21cells. The new isolates were identified using serological and molecular biological methods. RESULTS: 5410 mosquitoes were collected from the five cities in total. Three isolates produced CPE in C6/ 36 cell and five isolates produced CPE in both C6/36 and BHK-21 cell. Three isolates (LN0684, LN0688 and LN0689) were identified as Banna virus and one isolate (LN0636) was identified as Getah virus. Phylogenetic analysis showed that the three Banna virus strains were clustered into the same evolution branch as the other Chinese isolates. The identity of nucleotide sequence was between 91.2% and 94.7%, compared with other Banna virus strains. The new isolated Getah virus was clustered into the same branch with the strain of South Korea (swine). The identity of nucleotide sequence was 99.2%, when comparing with the strain of South Korea and was 95% to 99% with the strains from Russia, mainland of China and Taiwan region. Conclusion Eight virus isolates, including three Banna virus, one Getah virus and four unknown virus strains were isolated from mosquitoes in Liaoning province. Banna virus and Getah virus were reported for the first time in Liaoning province, while Getah virus showed the highest nucleotide homology with the South Korea strains.
PMID: 19565849
ISSN: 0254-6450
CID: 830522
Characterization of a sHsp of Schizosaccharomyces pombe, SpHsp15.8, and the implication of its functional mechanism by comparison with another sHsp, SpHsp16.0
Sugino, Chika; Hirose, Maya; Tohda, Hideki; Yoshinari, Yukiko; Abe, Tetsuya; Giga-Hama, Yuko; Iizuka, Ryo; Shimizu, Masafumi; Kidokoro, Shun-ichi; Ishii, Noriyuki; Yohda, Masafumi
There exist two small heat shock proteins (sHsps) in the fission yeast, Schizosaccharomyces pombe (S. pombe), whose expressions are highly induced by heat stress. We have previously expressed, purified, and characterized one of the sHsps, SpHsp16.0. In this study, we examined the other sHsp, SpHsp15.8. It suppressed the thermal aggregation of citrate synthase (CS) from porcine heart and dithiothreitol-induced aggregation of insulin from bovine pancreas with very high efficiency. Almost one SpHsp15.8 subunit was sufficient to protect one protein molecule from aggregation. Like SpHsp16.0, SpHsp15.8 dissociated into small oligomers and then interacted with denatured substrate proteins. SpHsp16.0 exhibited a clear enthalpy change for denaturation occurring over 60 degrees C in differential scanning calorimetry (DSC). However, we could not observe any significant enthalpy change in the DSC of SpHsp15.8. The difference is likely to be caused by the adhesive characteristics of SpHsp15.8. The oligomer dissociation of SpHsp15.8 and SpHsp16.0 and their interactions with denatured substrate proteins were studied by fluorescence polarization analysis (FPA). Both sHsps exhibited a temperature-dependent decrease of fluorescence polarization, which correlates with the dissociation of large oligomers to small oligomers. The dissociation of the SpHsp15.8 oligomer began at about 35 degrees C and proceeded gradually. On the contrary, the SpHsp16.0 oligomer was stable up to approximately 45 degrees C, but then dissociated into small oligomers abruptly at this temperature. Interestingly, SpHsp16.0 is likely to interact with denatured CS in the dissociated state, while SpHsp15.8 is likely to interact with CS in a large complex. These results suggest that S. pombe utilizes two sHsps that function in different manners, probably to cope with a wide range of temperatures and various denatured proteins.
PMID: 18543332
ISSN: 1097-0134
CID: 2983282