PubMed Health⌕ Search

Biomedical subjects

Daniel J Garry

Publications and source records attributed to Daniel J Garry.

32 records · Page 2Linked to original sources
PubMed2004

Persistent expression of the ATP-binding cassette transporter, Abcg2, identifies cardiac SP cells in the developing and adult heart.

Stem cells are important in the maintenance and repair of adult tissues. A population of cells, termed side population (SP) cells, has stem cell characteristics as they have been shown to contribute to diverse lineages. In this study, we confirm that Abcg2 is a determinant of the SP cell phenotype. Therefore, we examined Abcg2 expression during murine embryogenesis and observed robust expression in the blood islands of the E8.5 yolk sac and in developing tissues including the heart. During the latter stages of embryogenesis, Abcg2 identifies a rare cell population in the developing organs. We further establish that the adult heart contains an Abcg2 expressing SP cell population and these progenitor cells are capable of proliferation and differentiation. We define the molecular signature of cardiac SP cells and compare it to embryonic stem cells and adult cardiomyocytes using emerging technologies. We propose that the cardiac SP cell population functions as a progenitor cell population for the development, maintenance, and repair of the heart.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2004

Myoglobin: an essential hemoprotein in striated muscle.

Myoglobin is a cytoplasmic hemoprotein, expressed solely in cardiac myocytes and oxidative skeletal muscle fibers, that reversibly binds O2 by its heme residue, a porphyrin ring:iron ion complex. Since the initial discovery of its structure over 40 years ago, wide-ranging work by many investigators has added importantly to our understanding of its function and regulation. Functionally, myoglobin is well accepted as an O2-storage protein in muscle, capable of releasing O2 during periods of hypoxia or anoxia. Myoglobin is also thought to buffer intracellular O2 concentration when muscle activity increases and to facilitate intracellular O2 diffusion by providing a parallel path that augments simple diffusion of dissolved O2. The use of gene targeting and other molecular biological techniques has revealed important new insights into the developmental and environmental regulation of myoglobin and provided additional functions for this hemoprotein such as scavenging nitric oxide and reactive O2 species. These recent findings, coupled with additional emerging technologies and the discovery of other tissue globins, provide a framework for addressing new questions about myoglobin and readdressing old ones.

Animals↗
PubMed2004

Cellular and molecular regulation of skeletal muscle side population cells.

Muscle progenitor cells (satellite cells) function in the maintenance and repair of adult skeletal muscle. Side population (SP) cells are enriched in repopulating activity and also reside in adult skeletal muscle. In this study, we observed that Abcg2 is a determinant of the SP cell phenotype. Using reverse transcription polymerase chain reaction and immunohistochemical techniques, we localized Abcg2-expressing cells in the interstitium and in close approximation to the vasculature of adult skeletal muscle. Muscle SP cells are able to differentiate into myotubes and increase in number after cardiotoxin-induced muscle injury. Similar to myogenic progenitor cells, muscle SP cells express Foxk1 and are decreased in number in Foxk1 mutant skeletal muscle. Using emerging technologies, we examine the molecular signature of muscle SP cells from normal, injured, and Foxk1 mutant skeletal muscle to define common and distinct molecular programs. We propose that muscle SP cells are progenitor cells that participate in repair and regeneration of adult skeletal muscle.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2003

Cardiac progenitor cells from adult myocardium: homing, differentiation, and fusion after infarction.

Potential repair by cell grafting or mobilizing endogenous cells holds particular attraction in heart disease, where the meager capacity for cardiomyocyte proliferation likely contributes to the irreversibility of heart failure. Whether cardiac progenitors exist in adult myocardium itself is unanswered, as is the question whether undifferentiated cardiac precursor cells merely fuse with preexisting myocytes. Here we report the existence of adult heart-derived cardiac progenitor cells expressing stem cell antigen-1. Initially, the cells express neither cardiac structural genes nor Nkx2.5 but differentiate in vitro in response to 5'-azacytidine, in part depending on Bmpr1a, a receptor for bone morphogenetic proteins. Given intravenously after ischemia/reperfusion, cardiac stem cell antigen 1 cells home to injured myocardium. By using a Cre/Lox donor/recipient pair (alphaMHC-Cre/R26R), differentiation was shown to occur roughly equally, with and without fusion to host cells.

Animals↗
PubMed2003

Transcriptional profiling and regulation of the extracellular matrix during muscle regeneration.

Muscle regeneration is a complex process requiring the coordinated interaction between the myogenic progenitor cells or satellite cells, growth factors, cytokines, inflammatory components, vascular components and the extracellular matrix (ECM). Previous studies have elegantly described the physiological modulation of the regenerative process in response to muscle injury, but the molecular response that characterizes stages of the repair process remains ill-defined. The recent completion of the Human and Mouse Genome Projects and the advent of technologies such as high-density oligonucleotide array analysis facilitate an expanded analysis of complex processes such as muscle regeneration. In the present study, we define cellular and molecular events that characterize stages of muscle injury and regeneration. Utilization of transcriptional profiling strategies revealed coordinated expression of growth factors [i.e., Tgfb1, Igf1, Egf, chemokine (C-C motif) ligand 6 and 7], the fetal myogenic program (Myod1, Myf5, Myf6), and the biomatrix (procollagen genes, Mmp3, Mmp9, biglycan, periostin) during muscle regeneration. Corroboration of the transcriptional profiling analysis included quantitative real-time RT-PCR and in situ hybridization analyses of selected candidate genes. In situ hybridization studies for periostin [osteoblast-specific factor 2 (fasciclin I-like)] and biglycan revealed that these genes are restricted to mesenchymal derivatives during embryogenesis and are significantly regulated during regeneration of the injured hindlimb skeletal muscle. We conclude that muscle regeneration is a complex process that requires the coordinated modulation of the inflammatory response, myogenic progenitor cells, growth factors, and ECM for complete restoration of muscle architecture.

3T3 Cells↗
PubMed2003

Hypoxia-induced left ventricular dysfunction in myoglobin-deficient mice.

Myoglobin-deficient mice are viable and have preserved cardiac function due to their ability to mount a complex compensatory response involving increased vascularization and the induction of the hypoxia gene program (hypoxia-inducible factor-1alpha, endothelial PAS, heat shock protein27, etc.). To further define and explore functional roles for myoglobin, we challenged age- and gender-matched wild-type and myoglobin-null mice to chronic hypoxia (10% oxygen for 1 day to 3 wk). We observed a 30% reduction in cardiac systolic function in the myoglobin mutant mice exposed to chronic hypoxia with no changes observed in the wild-type control hearts. The cardiac dysfunction observed in the hypoxic myoglobin-null mice was reversible with reexposure to normoxic conditions and could be prevented with treatment of an inhibitor of nitric oxide (NO) synthases. These results support the conclusion that hypoxia-induced cardiac dysfunction in myoglobin-null mice occurs via a NO-mediated mechanism. Utilizing enzymatic assays for NO synthases and immunohistochemical analyses, we observed a marked induction of inducible NO synthase in the hypoxic myoglobin mutant ventricle compared with the wild-type hypoxic control ventricle. These new data establish that myoglobin is an important cytoplasmic cardiac hemoprotein that functions in regulating NO homeostasis within cardiomyocytes.

Animals↗
PubMed2003

RNA amplification and transcriptional profiling for analysis of stem cell populations.

As stem cells constitute a rare cell pool, a global analysis of gene expression is typically not possible. Here, we use a T7-based RNA amplification method combined with high-density oligonucleotide array technology to analyze gene expression. We isolated RNA from ES cells (100-100,000 cells), subjected them to two rounds of amplification, and compared each sample using microarray analysis. RNA isolation and amplification was highly reproducible and sensitive for the analysis of low abundant transcripts. Greater than 93% of the transcripts expressed were changed less than 2-fold when comparing the results of amplified RNA (100 cells to 100,000 cells) to unamplified RNA (isolated from 1,000,000 cells). This transcriptional analysis resulted in minimal skewing of gene expression. Using this technology, we analyzed the genetic programs of ES cells, STO feeder cells, and adult cardiomyocytes. We conclude that these technologies can be applied to the analysis of the genetic programs of rare cell populations and ultimately this analysis will enhance our understanding of the regulatory mechanisms of stem cell populations.

Animals↗
PubMed2003

Emerging roles for myoglobin in the heart.

Myoglobin (Mb) is an intensely studied hemoprotein that is restricted mainly to the heart and oxidative myofibers in skeletal muscle. Previous physiologic and pharmacologic studies have supported a role for Mb in facilitated oxygen transport or as an oxygen reservoir in striated muscle. Transgenic and gene disruption technologies have been utilized to produce mice that lack Mb. Studies utilizing these transgenic mouse models support the notion that Mb may have multiple, diverse functions in the heart. Future studies using these emerging technologies will further enhance the understanding of the role of Mb and other hemoproteins in cardiovascular biology.

Animals↗
PubMed2003

Stem cell biology and therapeutic applications.

PURPOSE OF REVIEW: Chronic diseases are common and deadly. Stem cell therapies have received intense interest for the repopulation of damaged or diseased tissues. A detailed understanding of the similarities and differences between embryonic stem cells and somatic stem cells will enhance our understanding of mechanisms of tissue repair or cellular augmentation. In addition, emerging technologies will be useful in the definition of the molecular regulation of the respective stem cell populations. RECENT FINDINGS: A number of postnatal tissues have a population of somatic stem cells, which function in the maintenance and repair of tissues. Using molecular technologies these somatic stem cell populations have been shown to be pluripotent when placed in a permissive environment. Recent studies have utilized emerging technologies to define a molecular signature of embryonic stem cells and selected somatic stem cell populations. These strategies will be useful for the definition of a molecular program that promotes a stem cell phenotype (i.e. stemness phenotype). SUMMARY: Recent studies suggest that embryonic and somatic stem cell populations hold promise as sources for tissue engineering. The use of cell biological and molecular technologies will enhance our understanding of embryonic and somatic stem cell populations and their molecular regulatory events that promote multipotentiation.

Germ Cells↗
PubMed2002

Absence of p21CIP rescues myogenic progenitor cell proliferative and regenerative capacity in Foxk1 null mice.

Foxk1 is a forkhead/winged helix transcription factor that is restricted to myogenic progenitor cells in adult skeletal muscle. Mice lacking Foxk1 (Foxk1-/-) display growth retardation and a severe impairment in skeletal muscle regeneration following injury. Here we show that myogenic progenitor cells from Foxk1-/- mice are reduced in number and have perturbed cell cycle progression (G(0)/G(1) arrest). Molecular analysis of Foxk1-/- myogenic progenitor cells revealed increased expression of the cyclin-dependent kinase inhibitor, p21(CIP), independent of changes in other cell cycle inhibitors, including p53. Combinatorial mating of Foxk1-/- mice with p21(CIP)-/- mice, to generate double mutant progeny, resulted in a complete restoration of the growth deficit, skeletal muscle regeneration, myogenic progenitor cell number, and cell cycle progression that characterized the Foxk1-/- mice. We conclude that Foxk1 is essential for regulating cell cycle progression in the myogenic progenitor cell and that the cyclin-dependent kinase inhibitor, p21(CIP), may be a downstream target of Foxk1.

Animals↗
PubMed2002

Cardiac dysfunction in mice lacking cytochrome-c oxidase subunit VIaH.

Cytochrome-c oxidase subunit VIaH (COXVIaH) has been implicated in the modulation of COX activity. A gene-targeting strategy was undertaken to generate mice that lacked COXVIaH to determine its role in regulation of oxidative energy production and mechanical performance in cardiac muscle. Total COX activity was decreased in hearts from mutant mice, which appears to be a consequence of altered assembly of the holoenzyme COX. However, total myocardial ATP was not significantly different in wild-type and mutant mice. Myocardial performance was examined using the isolated working heart preparation. As left atrial filling pressure increased, hearts from mutant mice were unable to generate equivalent stroke work compared with hearts from wild-type mice. Direct measurement of left ventricular end-diastolic volume using magnetic resonance imaging revealed that cardiac dysfunction was a consequence of impaired ventricular filling or diastolic dysfunction. These findings suggest that a genetic deficiency of COXVIaH has a measurable impact on myocardial diastolic performance despite the presence of normal cellular ATP levels.

Animals↗
PubMed2002

Neuroglobin, a novel member of the globin family, is expressed in focal regions of the brain.

Hemoproteins are widely distributed among unicellular eukaryotes, plants, and animals. In addition to myoglobin and hemoglobin, a third hemoprotein, neuroglobin, has recently been isolated from vertebrate brain. Although the functional role of this novel member of the globin family remains unclear, neuroglobin contains a heme-binding domain and may participate in diverse processes such as oxygen transport, oxygen storage, nitric oxide detoxification, or modulation of terminal oxidase activity. In this study we utilized in situ hybridization (ISH) and RT-PCR analyses to examine the expression of neuroglobin in the normoxic and hypoxic murine brain. In the normoxic adult mouse, neuroglobin expression was observed in focal regions of the brain, including the lateral tegmental nuclei, the preoptic nucleus, amygdala, locus coeruleus, and nucleus of the solitary tract. Using ISH and RT-PCR techniques, no significant changes in neuroglobin expression in the adult murine brain was observed in response to chronic 10% oxygen. These results support the hypothesis that neuroglobin is a hemoprotein that is expressed in the brain and may have diverse functional roles.

Animals↗