CD2AP is a potential prognostic biomarker of renal clear cell carcinoma.

BACKGROUND: CD2-associated protein (CD2AP) is a podocyte-associated gene and its reduced expression is associated with the development of proteinuria and glomerulosclerosis. However, few studies have focused on the correlation between the expression and prognosis of CD2AP in renal clear cell carcinoma (ccRCC). Therefore, we aimed to assess the regulation of CD2AP expression and prognostic value in ccRCC. METHODS: Multiple databases were employed to examine the expression of CD2AP in ccRCC. RT-qPCR, Western Blot and immunohistochemistry were used to validate CD2AP expression in different cell lines and tissue samples. Kaplan-Meier analysis and ROC curve analysis were performed on the predictive prognostic performance of CD2AP. COX regression was used to construct CD2AP-related prognostic models. The TIMER and TISIDB databases were used to analyze the correlation of tumor-infiltrating immune cells with gene expression, mutations, somatic copy number variation, and immune molecules. Mass spectrometry was used to detect methylation status of the promoter CpG site of CD2AP in multiple cells. RESULTS: We found that CD2AP expression was downregulated in ccRCC and its lower expression level was correlation with worse patient prognosis, higher tumor stage and grade and distant metastasis through analysis of databases, ccRCC cell lines and clinical tissue samples. Moreover, database and mass spectrometry techniques identified and validated cg12968598 hypermethylation as one of the key reasons for the downregulation of CD2AP expression. CD2AP expression was also associated with macrophage and neutrophil infiltration. CONCLUSIONS: Taken together, our results suggest that CD2AP can be used as a diagnostic and prognostic biomarker in ccRCC patients and that DNA hypermethylation plays an important role in reducing CD2AP expression.

[Correlation between methylation of interferon regulatory factor 6 gene promoter in renal tissues and overall survival of patients with Kidney renal clear cell carcinoma].

OBJECTIVE: To assess the prognostic value of methylation of interferon regulatory factor 6 (IRF6) gene promoter in patients diagnosed with Kidney renal clear cell carcinoma (KIRC). METHODS: The primary lesions of fifty KIRC patients who were diagnosed at the First Affiliated Hospital of Nanjing Medical University from January 2016 to January 2020 were collected. The expression of IRF6 protein was determined with an immunohistochemical method. The correlation between the level of IRF6 expression and survival and/or metastasis status was analyzed. The mRNA and protein levels of the IRF6 in KIRC and normal renal tissues were compared by using bioinformatic tools. The difference in the methylation rate of the IRF6 gene promoter between tumor and adjacent tissues was analyzed by searching the online databases. Statistical analysis was carried out for the methylation status of the IRF6 gene promoter region to select those negatively correlated with the overall survival (OS) among the patients. In vitro experiments were conducted with cell lines to verify the correlation between the status of promoter methylation and transcription level of the IRF6 gene. RESULTS: The mRNA and protein levels of the IRF6 gene in KIRC tissues were significantly lower than those of the normal controls, and this was more prominent in patients who had died or developed metastasis. The extent of IRF6 gene promoter methylation in the KIRC tissues was much higher compared with that of the adjacent normal renal tissues. There was a significant negative correlation between the methylation of the IRF6 gene promoter and mRNA level of the IRF6 (R = -0.52). The higher methylation degree in the IRF6 gene promoter regions cg12034118 and cg16030177, the shorter the OS and worse prognosis in the patients. Only twenty CpG sites in cg12034118 were confirmed to be highly methylated in KIRC cell lines. The transcription level of the IRF6 gene was upregulated in a time- and dose-dependent manner after the treatment with demethylation reagent 5-azadeoxycytidine. CONCLUSION: The methylation of IRF6 gene promoter in the renal tissues of KIRC patients is closely correlated with the OS. Cg12034118 may provide a promising biomarker for laboratory detection, and its high methylation rate has certain reference value for the prognosis.

Pan-cancer analysis identifies the IRF family as a biomarker for survival prognosis and immunotherapy.

IRF family genes have been shown to be crucial in tumorigenesis and tumour immunity. However, information about the role of IRF in the systematic assessment of pan-cancer and in predicting the efficacy of tumour therapy is still unknown. In this work, we performed a systematic analysis of IRF family genes in 33 tumour samples, including expression profiles, genomics and clinical characteristics. We then applied Single-Sample Gene-Set Enrichment Analysis (ssGSEA) to calculate IRF-scores and analysed the impact of IRF-scores on tumour progression, immune infiltration and treatment efficacy. Our results showed that genomic alterations, including SNPs, CNVs and DNA methylation, can lead to dysregulation of IRFs expression in tumours and participate in regulating multiple tumorigenesis. IRF-score expression differed significantly between 12 normal and tumour samples and the impact on tumour prognosis and immune infiltration depended on tumour type. IRF expression was correlated to drug sensitivity and to the expression of immune checkpoints and immune cell infiltration, suggesting that dysregulation of IRF family expression may be a critical factor affecting tumour drug response. Our study comprehensively characterizes the genomic and clinical profile of IRFs in pan-cancer and highlights their reliability and potential value as predictive markers of oncology drug efficacy. This may provide new ideas for future personalized oncology treatment.

Chiral-Controlled Cyclic Chemiluminescence Reactions for the Analysis of Enantiomer Amino Acids.

The similarity and complexity of chiral amino acids (AAs) in complex samples remain a significant challenge in their analysis. In this work, the chiral metal-organic framework (MOF)-controlled cyclic chemiluminescence (CCL) reaction is developed and utilized in the analysis of enantiomer AAs. The chiral MOF of d-Co0.75Zn0.25-MOF-74 is designed and prepared by modifying the Co0.75Zn0.25-MOF-74 with d-tartaric acid. The developed chiral bimetallic MOF can not only offer the chiral recognize sites but also act as the catalyst in the cyclic luminol-H2O2 reaction. Moreover, a distinguishable CCL signal can be obtained on enantiomer AAs via the luminol-H2O2 reaction with the control of d-Co0.75Zn0.25-MOF-74. The amplified difference of enantiomer AAs can be quantified by the decay coefficient (k-values) which are calculated from the exponential decay fitting of their obtained CCL signals. According to simulation results, the selective recognition of 19 pairs of AAs is controlled by the pore size of the MOF-74 and their hydrogen-bond interaction with d-tartaric acid on the chiral MOF. Furthermore, the k-values can also be used to estimate the change of chiral AAs in complex samples. Consequently, this chiral MOF-controlled CCL reaction is applied to differentiate enantiomer AAs involved in the quality monitoring of dairy products and auxiliary diagnosis, which provides a new approach for chiral studies and their potential applications.

NF-κB regulates the expression of STING via alternative promoter usage.

AIMS: Stimulator of interferon genes (STING) is a transmembrane protein in endoplasmic reticulum and plays crucial roles in autophagy, antiviral and anti-tumor responses. However, there are few studies on the transcriptional regulation mechanism of STING. MAIN METHODS: The 5' RACE experiment was used to determine the location of STING promoters. Luciferase reporting assay confirmed the activity and core region of STING internal promoter. Site-directed mutagenesis confirmed that NF-κB regulates the activity of STING promoters. The regulation of NF-κB on STING was investigated by real-time quantitative PCR, western blot, chromatin immunoprecipitation assay and lipopolysaccharide (LPS) inflammatory cell model. KEY FINDINGS: There was also a transcription start site at the 17 bp sequence upstream of STING second exon. STING-285 was the core region of the internal promoter. After NF-κB binding site mutation, the activity of STING internal promoter decreased significantly. In addition, we found that NF-κB can bind to the promoter region of wild-type STING. Overexpression of NF-κB significantly increased the activity of STING internal promoter and wild-type promoter, while knockdown of endogenous NF-κB significantly inhibited the activity of STING promoters. The binding of NF-κB to STING promoters in vivo were confirmed by chromatin immunoprecipitation assay. Meanwhile, we stimulated HeLa cells with LPS to activate the NF-κB pathway and found that STING expression was up-regulated. SIGNIFICANCE: These results suggest that transcription factor NF-κB positively regulates the expression of STING via alternative promoter usage. This provides a new basis and potential drug targets for the clinical treatment of STING related diseases.

5-Methylcytosine (m5C) Modification Patterns and Tumor Immune Infiltration Characteristics in Clear Cell Renal Cell Carcinoma.

Recently, studies have revealed the prognostic value of 5-methylcytosine (m5C) in clear cell renal cell carcinoma (ccRCC). However, the role of m5C methylation in ccRCC immune infiltration and the immunotherapeutic response remains unknown. Based on the mRNA expressions of 14 m5C regulators, we evaluated the m5C modification patterns of 530 tumor samples from the TCGA-ccRCC database. We used the principal component analysis (PCA) algorithm to construct individual patient m5Cscores to facilitate individual analysis of m5C modification patterns in ccRCC patients. We finally defined three different m5C modification patterns. Different clinical features and immune heterogeneity existed among the three patterns, and their immune infiltration characteristics could correspond to different immune phenotypes, including the immune-inflamed, immune-excluded, and immune-desert phenotype. We designed the m5Cscore calculated by the PCA algorithm to measure individual patients' m5C modification patterns. The low m5Cscore group presented with a positive prognosis, increased TMB, and immune activation. Additionally, low m5Cscore patients showed an increased response to immune checkpoint inhibitors. We further the value of the m5Cscore in predicting OS verified in four other tumor cohorts. Our findings revealed that m5C methylation modifications are essential in regulating ccRCC immune infiltration. Assessing single ccRCC patients' m5C modification patterns can fully improve our comprehension of tumor immune characteristics and be used to provide effective personalized immunotherapy strategies for clinical use.

Identification of IRF-associated molecular subtypes in clear cell renal cell carcinoma to characterize immunological characteristics and guide therapy.

Background: Recently studies have identified a critical role for interferon regulatory factor (IRF) in modulating tumour immune microenvironment (TME) infiltration and tumorigenesis. Methods: Based on IRF1-9 expression profiles, we classified all ccRCC samples into three molecular subtypes (clusters A-C) and characterized the prognosis and immune infiltration of these clusters. IRFscore constructed by principal component analysis was performed to quantify IRF-related subtypes in individual patients. Results: We proved that IRFscore predicted multiple patient characteristics, with high IRFscore group having poorer prognosis, suppressed TME, increased T-cell exhaustion, increased TMB and greater sensitivity to anti- PD-1/CTLA-4 therapies. Furthermore, analysis of metastatic ccRCC (mccRCC) molecular subtypes and drug sensitivity proved that low IRFscore was more sensitive to targeted therapies. Moreover, IRFscore grouping can be well matched to the immunological and molecular typing of ccRCC. qRT-PCR showed differential expression of IRFs in different cell lines. Conclusions: Evaluating IRF-related molecular subtypes in individual ccRCC patients not only facilitates our understanding of tumour immune infiltration, but also provides more effective clinical ideas for personalised treatment.

Hepatitis D: challenges in the estimation of true prevalence and laboratory diagnosis.

Hepatitis delta virus (HDV) is a defective single negative chain RNA virus, as its envelope protein synthesis is dependent on hepatitis B virus (HBV). Studies have consistently shown that coinfection of HBV and HDV is the most serious form of viral hepatitis, with accelerated progression to liver cirrhosis and hepatocellular carcinoma. About 74 million of HBV surface antigen (HBsAg) positive patients worldwide are also co-infected with HDV. Besides, patients with intravenous drug use and high-risk sexual behavior are at higher risk of HDV infection. Therapeutic schedules for HDV are limited, and relapse of HDV has been observed after treatment with pegylated interferon alpha. To reduce the transmission of HDV, all people infected with HBV should be screened for HDV. At present, several serological and molecular detection methods are widely used in the diagnosis of HDV. However, due to the lack of international standards diagnostic results from different laboratories are often not comparable. Therefore, the true prevalence of HDV is still unclear. In this manuscript, we have analyzed various factors influencing the estimation of HDV prevalence. We have also discussed about the advantages and disadvantages of currently available HDV laboratory diagnostic methods, in order to provide some ideas for improving the detection of HDV.

High Endothelial Venules Accelerate Naive T Cell Recruitment by Tumor Necrosis Factor-Mediated R-Ras Upregulation.

Recruitment of naive T cells to lymph nodes is essential for the development of adaptive immunity. Upon pathogen infection, lymph nodes promptly increase the influx of naive T cells from the circulation in order to screen and prime the T cells. The precise contribution of the lymph node vasculature to the regulation of this process remains unclear. Here we show a role for the Ras GTPase, R-Ras, in the functional adaptation of high endothelial venules to increase naive T cell trafficking to the lymph nodes. R-Ras is transiently up-regulated in the endothelium of high endothelial venules by the inflammatory cytokine tumor necrosis factor (TNF) within 24 hours of pathogen inoculation. TNF induces R-Ras upregulation in endothelial cells via JNK and p38 mitogen-activated protein kinase but not NF-κB. Studies of T cell trafficking found that the loss of function of endothelial R-Ras impairs the rapid acceleration of naive T cell recruitment to the lymph nodes upon inflammation. This defect diminished the ability of naive OT-1 T cells to develop antitumor activity against ovalbumin-expressing melanoma. Proteomic analyses suggest that endothelial R-Ras facilitates TNF-dependent transendothelial migration (diapedesis) of naive T cells by modulating molecular assembly the at T cell-endothelial cell interface. These findings give new mechanistic insights into the functional adaptation of high endothelial venules to accelerate naive T cell recruitment to the lymph nodes.

Oligomeric amyloid-beta induces MAPK-mediated activation of brain cytosolic and calcium-independent phospholipase A2 in a spatial-specific manner.

Alzheimer's disease (AD) is histopathologically characterized by the build-up of fibrillar amyloid beta (Aß) in the form of amyloid plaques and the development of intraneuronal neurofibrillary tangles consisting of aggregated hyperphosphorylated Tau. Although amyloid fibrils were originally considered responsible for AD pathogenesis, recent convincing evidence strongly implicates soluble oligomeric Aß as the primary neurotoxic species driving disease progression. A third largely ignored pathological hallmark, originally described by Alois Alzheimer, is the presence of "adipose inclusions", suggestive of aberrant lipid metabolism. The molecular mechanisms underlying these "lipoid granules", as well as their potential link to soluble and/or fibrillar Aß remain largely unknown. Seeking to better-understand these conundrums, we took advantage of the powerful technology of multidimensional mass spectrometry-based shotgun lipidomics and an AD transgenic mouse model overexpressing mutant amyloid precursor protein (APP E693Δ-Osaka-), where AD-like pathology and neurodegeneration occur as a consequence of oligomeric Aß accumulation in the absence of amyloid plaques. Our results revealed for the first time that APP overexpression and oligomeric Aß accumulation lead to an additive global accumulation of nonesterified polyunsaturated fatty acids (PUFAs) independently of amyloid plaques. Furthermore, we revealed that this accumulation is mediated by an increase in phospholipase A2 (PLA2) activity, evidenced by an accumulation of sn-1 lysophosphatidylcholine and by MAPK-mediated phosphorylation/activation of group IV Ca2+-dependent cytosolic (cPLA2) and the group VI Ca2+-independent PLA2 (iPLA2) independently of PKC. We further revealed that Aß-induced oxidative stress also disrupts lipid metabolism via reactive oxygen species-mediated phospholipid cleavage leading to increased sn-2 lysophosphatidylcholine as well as lipid peroxidation and the subsequent accumulation of 4-hydroxynonenal. Brain histological studies implicated cPLA2 activity with arachidonic acid accumulation within myelin-rich regions, and iPLA2 activity with docosahexaenoic acid accumulation within pyramidal neuron-rich regions. Taken together, our results suggest that PLA2-mediated accumulation of free PUFAs drives AD-related disruption of brain lipid metabolism.

Analysis of local bond-orientational order for liquid gallium at ambient pressure: Two types of cluster structures.

In terms of the local bond-orientational order (LBOO) parameters, a cluster approach to analyze local structures of simple liquids was developed. In this approach, a cluster is defined as a combination of neighboring seeds having at least nb local-orientational bonds and their nearest neighbors, and a cluster ensemble is a collection of clusters with a specified nb and number of seeds ns. This cluster analysis was applied to investigate the microscopic structures of liquid Ga at ambient pressure (AP). The liquid structures studied were generated through ab initio molecular dynamics simulations. By scrutinizing the static structure factors (SSFs) of cluster ensembles with different combinations of nb and ns, we found that liquid Ga at AP contained two types of cluster structures, one characterized by sixfold orientational symmetry and the other showing fourfold orientational symmetry. The SSFs of cluster structures with sixfold orientational symmetry were akin to the SSF of a hard-sphere fluid. On the contrary, the SSFs of cluster structures showing fourfold orientational symmetry behaved similarly as the anomalous SSF of liquid Ga at AP, which is well known for exhibiting a high-q shoulder. The local structures of a highly LBOO cluster whose SSF displayed a high-q shoulder were found to be more similar to the structure of ß-Ga than those of other solid phases of Ga. More generally, the cluster structures showing fourfold orientational symmetry have an inclination to resemble more to ß-Ga.

Novel molecular insights into the critical role of sulfatide in myelin maintenance/function.

Cerebroside sulfotransferase (CST) catalyzes the production of sulfatide, a major class of myelin-specific lipids. CST knockout (CST(-/-) ) mice in which sulfatide is completely depleted are born healthy, but display myelin abnormalities and progressive tremors starting at 4-6 weeks of age. Although these phenotypes suggest that sulfatide plays a critical role in myelin maintenance/function, the underlying mechanisms remain largely unknown. We analyzed the major CNS myelin proteins and the major lipids enriched in the myelin in a spatiotemporal manner. We found a one-third reduction of the major compact myelin proteins (myelin basic protein, myelin basic protein, and proteolipid protein, PLP) and an equivalent post-developmental loss of myelin lipids, providing the molecular basis behind the thinner myelin sheaths. Our lipidomics data demonstrated that the observed global reduction of myelin lipid content was not because of an increase of lipid degradation but rather to the reduction of their synthesis by oligodendrocytes. We also showed that sulfatide depletion leads to region-specific effects on non-compact myelin, dramatically affecting the paranode (neurofascin 155) and the major inner tongue myelin protein (myelin-associated glycoprotein). Moreover, we demonstrated that sulfatide promotes the interaction between adjacent PLP extracellular domains, evidenced by a progressive decline of high molecular weight PLP complexes in CST(-/-) mice, providing an explanation at a molecular level regarding the uncompacted myelin sheaths. Finally, we proposed that the dramatic losses of neurofascin 155 and PLP interactions are responsible for the progressive tremors and eventual ataxia. In summary, we unraveled novel molecular insights into the critical role of sulfatide in myelin maintenance/function. Cerebroside sulfotransferase (CST) catalyzes the production of sulfatide, a major class of myelin-specific lipids. CST knockout (CST(-/-) ) mice in which sulfatide is completely depleted are born healthy, but display myelin abnormalities We show in our study that sulfatide depletion leads to losses of myelin proteins and lipids, and impairment of myelin functions, unraveling novel molecular insights into the critical role of sulfatide in myelin maintenance/function.

Comprehensive and Quantitative Analysis of Polyphosphoinositide Species by Shotgun Lipidomics Revealed Their Alterations in db/db Mouse Brain.

Polyphosphoinositides (PPI) play crucial roles in cellular signaling and functions. However, comprehensively determining the changed levels of these species during different cellular processes has faced difficulties. Herein, we applied a novel methylation pattern recognition and simulation approach, and we exploited newly derived fragmentation patterns of methylated PPI species for comprehensive analysis of PPI species including phosphate position(s) and fatty acyl chains capable of circumpassing previous limitations. The developed method was applied for quantitative analysis of PPI species present in diabetic mouse cortex and liver, and it allowed us to unravel the marked reduction of PPI levels in brain cortices of db/db mice for the first time. Taken together, we developed a powerful and high-throughput method for comprehensive analysis of PPI species, which should greatly contribute to the elucidation of PPI biology under different disease states.

Role of integrin cross-regulation in parvovirus B19 targeting.

Most viral vectors used for gene therapy lack the ability to target a defined cell population. Parvovirus B19 has a restricted tropism for human erythroid progenitor cells and uses activated alpha5beta1 integrins as coreceptors for entry [Weigel-Kelley, K.A., Yoder, M.C., and Srivastava, A. (2003). Blood 102, 3927-3933]. In this study we examined the role of coexpressed integrins in alpha5beta1 integrin coreceptor function. Antibody-mediated cross-linking of beta1, beta2, and beta3 integrins and the integrin-associated protein (IAP) increased parvovirus B19 entry into nontarget K562 cells. Functional silencing of one integrin group, however, reduced the virus uptake- promoting function of a subsequently activated integrin group, indicating that the three integrins did not operate in isolation but through shared signaling pathways. This was further corroborated by direct competition between simultaneously clustered beta2 and beta1 integrins that could be overcome by stabilizing clustered beta1 integrins in a high-affinity conformation. In contrast, parvovirus B19 entry into primary erythroid progenitor cells was characterized by strong clustering-induced beta1 integrin coreceptor activity that was not abolished by subsequent beta2 and beta3 integrin activation and was, in fact, substantially increased in the presence of preclustered beta2 and beta3 integrins. Thus, integrin function is regulated in a cell type-specific manner through coexpressed integrins and preferential parvovirus B19 entry into erythroid progenitor cells is promoted by a robust beta1 integrin response that is enhanced through stable preclustering of coexpressed integrins. These results have implications for other viral vectors that use integrins as receptors/coreceptors and for gene therapy of hematopoietic progenitor cells using parvovirus B19 vectors.

Role of cellular FKBP52 protein in intracellular trafficking of recombinant adeno-associated virus 2 vectors.

We have reported that tyrosine-phosphorylated forms of a cellular protein, FKBP52, inhibit the second-strand DNA synthesis of adeno-associated virus 2 (AAV), leading to inefficient transgene expression from recombinant AAV vectors. To further explore the role of FKBP52 in AAV-mediated transduction, we established murine embryo fibroblasts (MEFs) cultures from FKBP52 wild-type (WT), heterozygous (HE), and knockout (KO) mice. Conventional AAV vectors failed to transduce WT MEFs efficiently, and the transduction efficiency was not significantly increased in HE or KO MEFs. AAV vectors failed to traffic efficiently to the nucleus in these cells. Treatment with hydroxyurea (HU) increased the transduction efficiency of conventional AAV vectors by approximately 25-fold in WT MEFs, but only by approximately 4-fold in KO MEFs. The use of self-complementary AAV (scAAV) vectors, which bypass the requirement of viral second-strand DNA synthesis, revealed that HU treatment increased the transduction efficiency approximately 23-fold in WT MEFs, but only approximately 4-fold in KO MEFs, indicating that the lack of HU treatment-mediated increase in KO MEFs was not due to failure of AAV to undergo viral second-strand DNA synthesis. Following HU treatment, approximately 59% of AAV genomes were present in the nuclear fraction from WT MEFs, but only approximately 28% in KO MEFs, indicating that the pathway by which HU treatment mediates nuclear transport of AAV was impaired in KO MEFs. When KO MEFs were stably transfected with an FKBP52 expression plasmid, HU treatment-mediated increase in the transduction efficiency was restored in these cells, which correlated directly with improved intracellular trafficking. Intact AAV particles were also shown to interact with FKBP52 as well as with dynein, a known cellular protein involved in AAV trafficking. These studies suggest that FKBP52, being a cellular chaperone protein, facilitates intracellular trafficking of AAV, which has implications in the optimal use of recombinant AAV vectors in human gene therapy.

Self-complementary adeno-associated virus 2 (AAV)-T cell protein tyrosine phosphatase vectors as helper viruses to improve transduction efficiency of conventional single-stranded AAV vectors in vitro and in vivo.

Recombinant vectors based on adeno-associated virus type 2 (AAV) target the liver efficiently, but the transgene expression is limited to approximately 5% of hepatocytes. The lack of efficient transduction is due, in part, to the presence of a cellular protein, FKBP52, phosphorylated forms of which inhibit the viral second-strand DNA synthesis. We have documented that dephosphorylation of FKBP52 at tyrosine residues by the cellular T cell protein tyrosine phosphatase (TC-PTP) enhances AAV-mediated transduction in primary murine hematopoietic cells from TC-PTP-transgenic mice. We have also documented that AAV-mediated transduction is significantly enhanced in hepatocytes in TC-PTP-transgenic as well as in FKBP52-deficient mice because of efficient viral second-strand DNA synthesis. In this study, we evaluated whether co-infection of conventional single-stranded AAV vectors with self-complementary AAV-TC-PTP vectors leads to increased transduction efficiency of conventional AAV vectors in established human cell lines in vitro and in primary murine hepatocytes in vivo. We demonstrate here that scAAV-TC-PTP vectors serve as a helper virus in augmenting the transduction efficiency of conventional AAV vectors in vitro as well as in vivo which correlates directly with the extent of second-strand DNA synthesis of conventional single-stranded AAV vectors. Toxicological studies following tail-vein injections of scAAV-TC-PTP vectors in experimental mice show no evidence of any adverse effect in any of the organs in any of the mice for up to 13 weeks. Thus, this novel co-infection strategy should be useful in circumventing one of the major obstacles in the optimal use of recombinant AAV vectors in human gene therapy.

Heat-shock treatment-mediated increase in transduction by recombinant adeno-associated virus 2 vectors is independent of the cellular heat-shock protein 90.

Recombinant adeno-associated virus 2 (AAV) vectors transduction efficiency varies greatly in different cell types. We have described that a cellular protein, FKBP52, in its phosphorylated form interacts with the D-sequence in the viral inverted terminal repeat, inhibits viral second strand DNA synthesis, and limits transgene expression. Here we investigated the role of cellular heat-shock protein 90 (HSP90) in AAV transduction because FKBP52 forms a complex with HSP90, and because heat-shock treatment augments AAV transduction efficiency. Heat-shock treatment of HeLa cells resulted in tyrosine dephosphorylation of FKBP52, led to stabilization of the FKBP52-HSP90 complex, and resulted in approximately 6-fold increase in AAV transduction. However, when HeLa cells were pre-treated with tyrphostin 23, a specific inhibitor of cellular epidermal growth factor receptor tyrosine kinase, which phosphorylates FKBP52 at tyrosine residues, heat-shock treatment resulted in a further 18-fold increase in AAV transduction. HSP90 was shown to be a part of the FKBP52-AAV D-sequence complex, but HSP90 by itself did not bind to the D-sequence. Geldanamycin treatment, which disrupts the HSP90-FKBP52 complex, resulted in >22-fold increase in AAV transduction in heat-shock-treated cells compared with heat shock alone. Deliberate overexpression of the human HSP90 gene resulted in a significant decrease in AAV-mediated transduction in tyrphostin 23-treated cells, whereas down-modulation of HSP90 levels led to a decrease in HSP90-FKBP52-AAV D-sequence complex formation, resulting in a significant increase in AAV transduction following pre-treatment with tyrphostin 23. These studies suggest that the observed increase in AAV transduction efficiency following heat-shock treatment is unlikely to be mediated by HSP90 alone and that increased levels of HSP90, in the absence of heat shock, facilitate binding of FKBP52 to the AAV D-sequence, thereby leading to inhibition of AAV-mediated transgene expression. These studies have implications in the optimal use of recombinant AAV vectors in human gene therapy.

Impaired nuclear transport and uncoating limit recombinant adeno-associated virus 2 vector-mediated transduction of primary murine hematopoietic cells.

Controversies abound concerning hematopoietic stem cell transduction by recombinant adeno-associated virus 2 (AAV) vectors. For human hematopoietic cells, we have shown that this problem is related to the extent of expression of the cellular receptor for AAV. At least a small subset of murine hematopoietic cells, on the other hand, does express both the AAV receptor and the coreceptor, yet is transduced poorly. In the present study, we have found that approximately 85% of AAV genomes were present in the cytoplasmic fraction of primary murine c-Kit(+)Lin- hematopoietic cells. However, when mice were injected intraperitoneally with hydroxyurea before isolation of these cells, the extent to which AAV genomes were detected in the cytoplasmic fraction was reduced to approximately 40%, with a corresponding increase to approximately 60% in the nuclear fraction, indicating that hydroxyurea facilitated nuclear transport of AAV. It was apparent, nonetheless, that a significant fraction of the AAV genomes present in the nuclear fraction from cells obtained from hydroxyurea-treated mice was single stranded. We next tested whether the single-stranded AAV genomes were derived from virions that failed to undergo uncoating in the nucleus. A substantial fraction of the signal in the nuclear fraction of hematopoietic cells obtained from hydroxyurea-treated mice was also resistant to DNase I. That AAV particles were intact and biologically active was determined by successful transduction of 293 cells by virions recovered from murine hematopoietic cells 48 hr postinfection. Although hydroxyurea facilitated nuclear transport of AAV, most of the virions failed to undergo uncoating, thereby leading to only a partial improvement in viral second- strand DNA synthesis and transgene expression. A better understanding of the underlying mechanism of viral uncoating has implications in the optimal use of recombinant AAV vectors in hematopoietic stem cell gene therapy.

Adeno-associated virus type 2-mediated gene transfer: role of cellular T-cell protein tyrosine phosphatase in transgene expression in established cell lines in vitro and transgenic mice in vivo.

The use of adeno-associated virus type 2 (AAV) vectors has gained attention as a potentially useful alternative to the more commonly used retrovirus and adenovirus vectors for human gene therapy. However, the transduction efficiency of AAV vectors varies greatly in different cells and tissues in vitro and in vivo. We have documented that a cellular protein that binds the immunosuppressant drug FK506, termed the FK506-binding protein (FKBP52), interacts with the single-stranded D sequence within the AAV inverted terminal repeats, inhibits viral second-strand DNA synthesis, and consequently limits high-efficiency transgene expression (K. Qing, J. Hansen, K. A. Weigel-Kelley, M. Tan, S. Zhou, and A. Srivastava, J. Virol., 75: 8968-8976, 2001). FKBP52 can be phosphorylated at both tyrosine and serine/threonine residues, but only the phosphorylated forms of FKBP52 interact with the D sequence. Furthermore, the tyrosine-phosphorylated FKBP52 inhibits AAV second-strand DNA synthesis by greater than 90%, and the serine/threonine-phosphorylated FKBP52 causes approximately 40% inhibition, whereas the dephosphorylated FKBP52 has no effect on AAV second-strand DNA synthesis. In the present study, we have identified that the tyrosine-phosphorylated form of FKBP52 is a substrate for the cellular T-cell protein tyrosine phosphatase (TC-PTP). Deliberate overexpression of the murine wild-type (wt) TC-PTP gene, but not that of a cysteine-to-serine (C-S) mutant, caused tyrosine dephosphorylation of FKBP52, leading to efficient viral second-strand DNA synthesis and resulting in a significant increase in AAV-mediated transduction efficiency in HeLa cells in vitro. Both wt and C-S mutant TC-PTP expression cassettes were also used to generate transgenic mice. Primitive hematopoietic stem/progenitor cells from wt TC-PTP-transgenic mice, but not from C-S mutant TC-PTP-transgenic mice, could be successfully transduced by recombinant AAV vectors. These studies corroborate the fact that tyrosine phosphorylation of the cellular FKBP52 protein strongly influences AAV transduction efficiency, which may have important implications in the optimal use of AAV vectors in human gene therapy.

FKBP12 is the only FK506 binding protein mediating T-cell inhibition by the immunosuppressant FK506.

BACKGROUND: FK506-binding proteins (FKBP) are immunophilins that interact with the immunosuppressive drugs FK506 and rapamycin. Several FKBP family members such as FKBP12, FKBP12.6, and FKBP51 are expressed in T cells. It has been speculated that these FKBPs are possibly redundant in the immunosuppressant-induced T-cell inactivation. To determine the pharmacological relevance of multiple FKBP members in the immunosuppressant-induced T-cell inactivation, we have investigated the physiological responses of FKBP12-deficient and FKBP12.6-deficient mutant T cells to the immunosuppressive agent FK506. METHODS: FKBP12-deficient and FKBP12.6-deficient T cells were isolated from genetically engineered FKBP12-deficient and FKBP12.6-deficient mice, respectively. T-cell growth inhibitory assay was used to assess their responses to immunosuppressant FK506 treatments. RESULTS: We found that growth inhibition induced by FK506 is abolished in FKBP12-deficient cells but not in FKBP12.6-deficient cells. CONCLUSIONS: FKBP12 is the only FKBP family member that plays a key role in immunosuppressant-mediated immunosuppression.