A streamlined tandem tip-based workflow for sensitive nanoscale phosphoproteomics

Effective phosphoproteome of nanoscale sample analysis remains a daunting task, primarily due to significant sample loss associated with non-specific surface adsorption during enrichment of low stoichiometric phosphopeptide. We develop a tandem tip phosphoproteomics sample preparation method that is capable of sample cleanup and enrichment without additional sample transfer, and its integration with our recently developed SOP (Surfactant-assisted One-Pot sample preparation) and iBASIL (improved Boosting to Amplify Signal with Isobaric Labeling) approaches provides a streamlined workflow enabling sensitive, high-throughput nanoscale phosphoproteome measurements. This approach significantly reduces both sample loss and processing time, allowing the identification of >3000 (>9500) phosphopeptides from 1 (10) µg of cell lysate using the label-free method without a spectral library. It also enables precise quantification of ~600 phosphopeptides from 100 sorted cells (single-cell level input for the enriched phosphopeptides) and ~700 phosphopeptides from human spleen tissue voxels with a spatial resolution of 200 µm (equivalent to ~100 cells) in a high-throughput manner. The new workflow opens avenues for phosphoproteome profiling of mass-limited samples at the low nanogram level.

AAV Gene Therapy Utilizing Glycosylation-Independent Lysosomal Targeting Tagged GAA in the Hypoglossal Motor System of Pompe Mice

Pompe disease is caused by mutations in the gene encoding the lysosomal glycogen-metabolizing enzyme, acid-alpha glucosidase (GAA). Tongue myofibers and hypoglossal motoneurons appear to be particularly susceptible in Pompe disease. Here we used intramuscular delivery of adeno-associated virus serotype 9 (AAV9) for targeted delivery of an enhanced form of GAA to tongue myofibers and motoneurons in 6-month-old Pompe (Gaa -/- ) mice. We hypothesized that addition of a glycosylation-independent lysosomal targeting tag to the protein would result in enhanced expression in tongue (hypoglossal) motoneurons when compared to the untagged GAA. Mice received an injection into the base of the tongue with AAV9 encoding either the tagged or untagged enzyme; tissues were harvested 4 months later. Both AAV9 constructs effectively drove GAA expression in lingual myofibers and hypoglossal motoneurons. However, mice treated with the AAV9 construct encoding the modified GAA enzyme had a >200% increase in the number of GAA-positive motoneurons as compared to the untagged GAA (p < 0.008). Our results confirm that tongue delivery of AAV9-encoding GAA can effectively target tongue myofibers and associated motoneurons in Pompe mice and indicate that the effectiveness of this approach can be improved by addition of the glycosylation-independent lysosomal targeting tag.

Disrupting Inflammation-Associated CXCL8-CXCR1 Signaling Inhibits Tumorigenicity Initiated by Sporadic- and Colitis-Colon Cancer Stem Cells

Dysfunctional inflammatory pathways are associated with an increased risk of cancer, including colorectal cancer. We have previously identified and enriched for a self-renewing, colon cancer stem cell (CCSC) subpopulation in primary sporadic colorectal cancers (CRC) and a related subpopulation in ulcerative colitis (UC) patients defined by the stem cell marker, aldehyde dehydrogenase (ALDH). Subsequent work demonstrated that CCSC-initiated tumors are dependent on the inflammatory chemokine, CXCL8, a known inducer of tumor proliferation, angiogenesis and invasion. Here, we use RNA interference to target CXCL8 and its receptor, CXCR1, to establish the existence of a functional signaling pathway promoting tumor growth initiated by sporadic and colitis CCSCs. Knocking down either CXCL8 or CXCR1 had a dramatic effect on inhibiting both in vitro proliferation and angiogenesis. Likewise, tumorigenicity was significantly inhibited due to reduced levels of proliferation and angiogenesis. Decreased expression of cycle cell regulators cyclins D1 and B1 along with increased p21 levels suggested that the reduction in tumor growth is due to dysregulation of cell cycle progression. Therapeutically targeting the CXCL8-CXCR1 signaling pathway has the potential to block sustained tumorigenesis by inhibiting both CCSC- and pCCSC-induced proliferation and angiogenesis.

Transfer of Therapeutic Genes into Fetal Rhesus Monkeys Using Recombinant Adeno-Associated Type I Viral Vectors

Neuromuscular disorders such as Pompe disease (glycogen storage disease, type II), result in early and potentially irreversible cellular damage with a very limited opportunity for intervention in the newborn period. Pompe disease is due to deficiency in acid α-glucosidase (GAA) leading to lysosomal accumulation of glycogen in all cell types, abnormal myofibrillogenesis, respiratory insufficiency, neurological deficits, and reduced contractile function in striated muscle. Previous studies have shown that fetal delivery of recombinant adeno-associated virus (rAAV) encoding GAA to the peritoneal cavity of Gaa^-/- mice resulted in high-level transduction of the diaphragm. While progression of other genetic disorders may occur later in life, the potential of fetal gene delivery to avoid the onset of irreversible damage suggests it is an attractive option for many inherited diseases. In this study, rhesus monkey fetuses were administered 4.5 × 10¹² particles of rAAV type 1 expressing human GAA (rAAV1-CMV-hGAA), human α-1-antitrypsin (rAAV1-CBA-hAAT), or human mini-dystrophin (rAAV1-CMV-miniDMD) in the late first trimester using an established intraperitoneal ultrasound-guided approach. Fetuses were monitored sonographically and newborns delivered at term for postnatal studies. All animals remained healthy during the study period (growth, hematology, and clinical chemistry), with no evidence of adverse effects. Tissues were collected at a postnatal age of 3 months (∼7 months post-fetal gene transfer) for immunohistochemistry (IHC) and quantitative PCR. Both the diaphragm and peritoneum from vector-treated animals were strongly positive for expression of human GAA, AAT, or dystrophin by IHC, similar to findings when reporter genes were used. Protein expression in the diaphragm and peritoneum correlated with high vector copy numbers detected by real-time PCR. Other anatomical areas were negative, although the liver showed minimal evidence of human GAA, AAT, and DMD, vector genomes. In summary, delivery of rAAV vectors provided stable transduction of the muscular component of the diaphragm without any evidence of adverse effects.

Suppression of islet homeostasis protein thwarts diabetes mellitus progression

During progression to type 1 diabetes, insulin-producing β-cells are lost through an autoimmune attack resulting in unrestrained glucagon expression and secretion, activation of glycogenolysis, and escalating hyperglycemia. We recently identified a protein, designated islet homeostasis protein (IHoP), which specifically co-localizes within glucagon-positive α-cells and is overexpressed in the islets of both post-onset non-obese diabetic (NOD) mice and type 1 diabetes patients. Here we report that in the αTC1.9 mouse α-cell line, IHoP was released in response to high-glucose challenge and was found to regulate secretion of glucagon. We also show that in NOD mice with diabetes, major histocompatibility complex class II was upregulated in islets. In addition hyperglycemia was modulated in NOD mice via suppression of IHoP utilizing small interfering RNA (IHoP-siRNA) constructs/approaches. Suppression of IHoP in the pre-diabetes setting maintained normoglycemia, glyconeolysis, and fostered β-cell restoration in NOD mice 35 weeks post treatment. Furthermore, we performed adoptive transfer experiments using splenocytes from IHoP-siRNA-treated NOD/ShiLtJ mice, which thwarted the development of hyperglycemia and the extent of insulitis seen in recipient mice. Last, IHoP can be detected in the serum of human type 1 diabetes patients and could potentially serve as an early novel biomarker for type 1 diabetes in patients.

Assessment of abdominoperineal resection rate as a surrogate marker of hospital quality in rectal cancer surgery

Background

Rates of abdominoperineal resection (APR) have been suggested as a solitary surrogate marker for comparing overall hospital quality in rectal cancer surgery. This study investigated the value of this marker by examining the associations between hospital APR rates and other quality indicators.

Methods

Hospital-level correlations between risk-adjusted APR rates for low rectal cancer and six risk-adjusted outcomes and six care processes were performed (such as 30-day mortality, complications, timely treatment). The ability of APR rates to discriminate between hospitals' performance was examined by means of hospital variance results in multilevel regression models and funnel plots.

Results

A linked population-based data set identified 1703 patients diagnosed in 2007 and 2008 who underwent surgery for rectal cancer. Some 15·9 (95 per cent confidence interval (c.i.) 14·2 to 17·6) per cent of these patients had an APR. Among 707 people with low rectal cancer, 38·2 (34·6 to 41·8) per cent underwent APR. Although risk-adjusted hospital rates of APR for low rectal cancer varied by up to 100 per cent, only one hospital (1 per cent) fell outside funnel plot limits and hospital variance in multilevel models was not very large. Lower hospital rates of APR for low rectal cancer did not correlate significantly with better hospital-level outcomes or process measures, except for recording of pathological stage (r = −0·55, P = 0·019). Patients were significantly more likely to undergo APR for low rectal cancer if they attended a non-tertiary metropolitan hospital (adjusted odds ratio 2·14, 95 per cent c.i. 1·11 to 4·15).

Conclusion

APR rates do not appear to be a useful surrogate marker of overall hospital performance in rectal cancer surgery.

An acidic oligopeptide displayed on AAV2 improves axial muscle tropism after systemic delivery

Background

The appropriate tropism of adeno-associated virus (AAV) vectors that are systemically injected is crucial for successful gene therapy when local injection is not practical. Acidic oligopeptides have been shown to enhance drug delivery to bones.

Methods

In this study six-L aspartic acids (D6) were inserted into the AAV2 capsid protein sequence between amino acid residues 587 and 588. 129SVE mice were injected with double-stranded wild-type- (WT-) or D6-AAV2 mCherry expression vectors (3.24 x 10¹⁰ vg per animal) via the superficial temporal vein within 24 hours of birth.

Results

Fluorescence microscopy and quantitative polymerase chain reaction confirmed higher levels of mCherry expression in the paraspinal and gluteus muscles in the D6-AAV2 injected mice. The results revealed that although D6-AAV2 was less efficient in the transduction of immortalized cells stronger mCherry signals were detected over the spine and pelvis by live imaging in the D6-AAV2-injected mice than were detected in the WT-AAV2-injected mice. In addition, D6-AAV2 lost the liver tropism observed for WT-AAV2.

Conclusions

An acidic oligopeptide displayed on AAV2 improves axial muscle tropism and decreases liver tropism after systemic delivery. This modification should be useful in creating AAV vectors that are suitable for gene therapy for diseases involving the proximal muscles.

Intrinsic and extrinsic effects of mafG deficiency on hematopoietic recovery following bone marrow transplant

OBJECTIVE

MafG is the small subunit of the transcription factor NF-E2 that controls terminal megakaryocyte maturation and platelet release. Studies were conducted to evaluate the intrinsic and extrinsic effects of mafG deficiency on bone marrow engraftment kinetics.

MATERIALS AND METHODS

We used mafG knockout mice either as donors or recipients in bone marrow transplantations with wild-type mice and compared the engraftment kinetics to transplantations using wild-type donors and recipients. We measured peripheral cell counts, the presence of circulating donor-derived cells by flow cytometry, changes in the cellularity of the bone marrow and splenic weight on day 5, 7, 14, and 1 month post-transplantation.

RESULTS

Compared to wild-type recipients, mafG recipients had delayed platelet and leukocyte recovery and lower spleen weight at early time points after transplantation. Intrinsic effects: When mafG-deficient bone marrow served as donor source, we observed more rapid recovery of bone marrow cellularity and increased splenic hematopoiesis. The finding of increased short-term hematopoietic stem cells and progenitors in the mafG-deficient bone marrow could explain the accelerated hematopoietic recovery after transplantation. Furthermore, the expression of Bach 2, which can form a heterodimer with mafG protein, was found to be greatly reduced, while Notch 1 expression was increased in mafG-deficient mice. Extrinsic effects: When mafG-deficient mice were transplant recipients, there were delays in recovery of normal levels of marrow and splenic hematopoiesis as well as circulating leukocytes and platelets.

CONCLUSIONS

Our study demonstrates that mafG expression has intrinsic and extrinsic effects on hematopoietic engraftment following bone marrow transplantation.

Sites and kinetics of donor thrombopoiesis following transplantation of whole bone marrow and progenitor subsets

INTRODUCTION

Little is known about the sites and kinetics of thrombopoiesis following bone marrow transplant. The spleen is a site of hematopoiesis in a healthy mouse, and hematopoietic activity increases in response to stress. We hypothesized that the spleen is a major site of early post-transplant thrombopoiesis.

METHODS

We transplanted whole bone marrow (WBM) or lineage depleted progenitor subsets fractionated based on expression of c-kit and Sca-1 from transgenic mice expressing green fluorescent protein into lethally irradiated C57BL/6 recipients. We also transplanted whole bone marrow cells into healthy and splenectomized mice. Post-transplant megakaryopoiesis was assessed by measuring circulating platelet number, percent donor-derived platelets, bone marrow cellularity, splenic weight, megakaryocyte size, and megakaryocyte concentration from hour 3 to day 28 post transplant.

RESULTS

Following transplant, circulating donor-derived platelets were derived only from c-kit expressing subsets. Donor-derived platelets first appeared on post-transplant day five. Splenectomy reduced the number of these earliest circulating platelets. Splenic megakaryopoiesis increased dramatically from day 7-14 post-transplant. However, splenectomy accelerated platelet engraftment during this time frame.

CONCLUSION

Overall, these results demonstrate that the first platelets are produced by c-kit expressing megakaryocyte progenitors in the bone marrow and spleen. After post-transplant day 5, the net effect of the spleen on thrombopoiesis is to slow engraftment due to immune effects or hypersplenism.

The role of the donor in the repair of the marrow vascular niche following hematopoietic stem cell transplant

Bone marrow sinusoids maintain homeostasis between developing hematopoietic cells and the circulation, and they provide niches for hematopoietic progenitors. Sinusoids are damaged by chemotherapy and radiation. Hematopoietic stem cells (HSCs) have been shown to produce endothelial progenitor cells that contribute to the repair of damaged blood vessels. Because HSCs home to the marrow during bone marrow transplant, these cells may play a role in repair of marrow sinusoids. Here, we explore the role of donor HSCs in the repair of damaged sinusoids following hematopoietic stem cell transplant. We used three methods to test this role: (a) expression of platelet endothelial cell adhesion molecule to identify endothelial progenitors and the presence of the Y chromosome to identify male donor cells in female recipients; (b) presence of the Y chromosome to identify male donor cells in female recipients, and expression of the panendothelial marker mouse endothelial cell antigen-32 to identify sinusoidal endothelium; and (c) use of Tie-2/green fluorescent protein mice as donors or recipients and presence of Dil-Ac-LDL to identify sinusoids. We found that sinusoids were predominantly host-derived posttransplant. Donor cells spread along the marrow vasculature early post-transplant in a pattern that matched stromal-derived factor-1 expression. Furthermore, these engrafting progenitors were positioned to provide physical support, as well as growth and survival signals in the form of vascular-endothelial growth factor-A. Occasionally, donor cells provide cellular "patches" in the damaged sinusoids, although this occurred at a low level compared with hematopoietic engraftment. Donor support for the repair of the marrow vascular niche may be a critical first step of hematopoietic engraftment.

Mesenchymal stem cells spontaneously express neural proteins in culture and are neurogenic after transplantation

Reports of neural transdifferentiation of mesenchymal stem cells (MSCs) suggest the possibility that these cells may serve as a source for stem cell-based regenerative medicine to treat neurological disorders. However, some recent studies controvert previous reports of MSC neurogenecity. In the current study, we evaluate the neural differentiation potential of mouse bone marrow-derived MSCs. Surprisingly, we found that MSCs spontaneously express certain neuronal phenotype markers in culture, in the absence of specialized induction reagents. A previously published neural induction protocol that elevates cytoplasmic cyclic AMP does not upregulate neuron-specific protein expression significantly in MSCs but does significantly increase expression of the astrocyte-specific glial fibrillary acidic protein. Finally, when grafted into the lateral ventricles of neonatal mouse brain, MSCs migrate extensively and differentiate into olfactory bulb granule cells and periventricular astrocytes, without evidence of cell fusion. These results indicate that MSCs may be "primed" toward a neural fate by the constitutive expression of neuronal antigens and that they seem to respond with an appropriate neural pattern of differentiation when exposed to the environment of the developing brain.

Adult human hematopoietic cells provide functional hemangioblast activity

The murine adult hematopoietic stem cell is able to function as a hemangioblast, contributing both to blood reconstitution and to blood vessel repair in response to ischemic injury. We developed a novel mouse xenotransplantation model of retinal neovascularization to test human hematopoietic cell plasticity. Immunocompromised nonobese diabetic (NOD)/scid mice underwent myeloablative conditioning and transplantation with human CD34+ umbilical cord blood. After multilineage reconstitution was established, retinal ischemia was induced to promote neovascularization. Our results demonstrate human retinal neovascularization, thus revealing the functional hemangioblast activity of human hematopoietic cells.

SDF-1alpha/CXCR4: a mechanism for hepatic oval cell activation and bone marrow stem cell recruitment to the injured liver of rats

Stromal derived factor-1 alpha (SDF-1alpha) and its receptor CXCR4 have been shown to play a role in the systematic movement of hematopoietic stem cells (HSC) in the fetal and adult stages of hematopoiesis. Under certain physiological conditions liver oval cells can participate in the regeneration of the liver. We have shown that a percentage of oval cells are of hematopoietic origin. Others have shown that bone marrow derived stem cells can participate in liver regeneration as well. In this study we examined the role of SDF-1alpha and its receptor CXCR4 as a possible mechanism for oval cell activation in oval cell aided liver regeneration. In massive liver injury models where oval cell repair is involved hepatocytes up-regulate the expression of SDF-1alpha, a potent chemoattractant for hematopoietic cells. However, when moderate liver injury occurs, proliferation of resident hepatocytes repairs the injury. Under these conditions SDF-1alpha expression is not up-regulated and oval cells are not activated in the liver. In addition, we show that oval cells express CXCR4, the only known receptor for SDF-1alpha. Lastly, in vitro chemotaxis assays demonstrated that oval cells migrate along a SDF-1alpha gradient which suggests that the SDF-1alpha/CXCR4 interaction is a mechanism by which the oval cell compartment could be activated and possibly recruit a second wave of bone marrow stem cells to the injured liver. In conclusion, these experiments begin to shed light on a possible mechanism, which may someday lead to a better understanding of the hepatic and hematopoietic interaction in oval cell aided liver regeneration.