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Biomedical subjects

Joan B Mannick

Publications and source records attributed to Joan B Mannick.

6 recordsLinked to original sources
PubMed2006

S-nitrosothiol depletion in amyotrophic lateral sclerosis.

Recent data suggest that either excessive or deficient levels of protein S-nitrosylation may contribute to disease. Disruption of S-nitrosothiol (SNO) homeostasis may result not only from altered nitric oxide (NO) synthase activity but also from alterations in the activity of denitrosylases that remove NO groups. A subset of patients with familial amyotrophic lateral sclerosis (ALS) have mutations in superoxide dismutase 1 (SOD1) that increase the denitrosylase activity of SOD1. Here, we show that the increased denitrosylase activity of SOD1 mutants leads to an aberrant decrease in intracellular protein and peptide S-nitrosylation in cell and animal models of ALS. Deficient S-nitrosylation is particularly prominent in the mitochondria of cells expressing SOD1 mutants. Our results suggest that SNO depletion disrupts the function and/or subcellular localization of proteins that are regulated by S-nitrosylation such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and thereby contributes to ALS pathogenesis. Repletion of intracellular SNO levels with SNO donor compounds rescues cells from mutant SOD1-induced death. These results suggest that aberrant depletion of intracellular SNOs contributes to motor neuron death in ALS, and raises the possibility that deficient S-nitrosylation is a general mechanism of disease pathogenesis. SNO donor compounds may provide new therapeutic options for diseases such as ALS that are associated with deficient S-nitrosylation.

Active Transport, Cell Nucleus↗
PubMed2006

Immunoregulatory and antimicrobial effects of nitrogen oxides.

The therapeutic effects of inhaled nitric oxide (NO) therapy are thought to be restricted to the pulmonary vasculature because of rapid inactivation of NO by hemoglobin in the bloodstream. However, recent data suggest that inhaled NO may not only be scavenged by the heme iron of hemoglobin but also may react with protein thiols in the bloodstream, including cysteine-93 of the hemoglobin B subunit. Reaction of NO with protein or peptide thiols is termed S-nitrosylation and results in the formation of relatively stable protein S-nitrosothiols that carry NO bioactivity to distal organs. Thus, inhaled NO-induced protein S-nitrosylation may allow inhaled NO to have multiple as yet undiscovered physiologic and pathophysiologic effects outside of the lung. Here we review the immunoregulatory and antimicrobial functions of NO and the potential effects of inhaled NO therapy on host defense.

Administration, Inhalation↗
PubMed2005

Assessment of S-nitrosothiols on diaminofluorescein gels.

S-Nitrosylation is the modification of a cysteine thiol on a protein or peptide by a nitric oxide (NO) group. Increasing evidence suggests that S-nitrosylation of critical cysteine residues regulates protein function and cell signaling. However, progress in the field has been hampered by a lack of accurate and easy methods for detecting S-nitrosylation and other labile NO-based modifications in samples. We have developed a rapid method for analyzing protein and peptide S-nitrosothiols on gels using the fluorescent probes 4,5-diaminofluorescein (DAF-2) and 3-amino,4-aminomethyl-2'7'-difluorescein (DAF-FM). Low micromolar levels of S-nitrosylated bovine serum albumin (BSA), but not control BSA, are detected on the gels. In addition, NO-based modifications of proteins and peptides on nonsulfur groups (e.g., carbon, oxygen, nitrogen) are detected on DAF gels. Analysis of intracellular proteins on DAF gels indicated that the NO donor compound S-nitrosoglutathione S-nitrosylates significantly more proteins in mitochondrial lysates than in cytoplasmic lysates. In summary, the use of DAF gels is an easy method to analyze in vitro protein and peptide S-nitrosylation. The assay is also the first gel-based method to identify not only S-nitrosothiols but also other labile NO-based modifications of proteins and peptides.

Fluorescein↗
PubMed2004

NO means no and yes: regulation of cell signaling by protein nitrosylation.

Protein nitrosylation is emerging as a key mechanism by which nitric oxide regulates cell signaling. Nitrosylation is the binding of a NO group to a metal or thiol (-SH) on a peptide or protein. Like phosphorylation, nitrosylation is a precisely targeted and rapidly reversible posttranslational modification that allows cells to flexibly and specifically respond to changes in their environment. An increasing number of proteins have been identified whose activity is regulated by intracellular nitrosylation. This review focuses on proteins regulated by endogenous nitrosylation, the chemistry underlying nitrosylation, the specificity and reversibility of nitrosylation reactions, methods to detect protein nitrosylation, and the role of coordinated protein nitrosylation/denitrosylation in cell signaling.

Animals↗
PubMed2003

Nitrosylation of cytochrome c during apoptosis.

Cytochrome c released from mitochondria into the cytoplasm plays a critical role in many forms of apoptosis by stimulating apoptosome formation and subsequent caspase activation. However, the mechanisms regulating cytochrome c apoptotic activity are not understood. Here we demonstrate that cytochrome c is nitrosylated on its heme iron during apoptosis. Nitrosylated cytochrome c is found predominantly in the cytoplasm in control cells. In contrast, when cytochrome c release from mitochondria is inhibited by overexpression of the anti-apoptotic proteins B cell lymphoma/leukemia (Bcl)-2 or Bcl-X(L), nitrosylated cytochrome c is found in the mitochondria. These data suggest that during apoptosis, cytochrome c is nitrosylated in mitochondria and then rapidly released into the cytoplasm in the absence of Bcl-2 or Bcl-X(L) overexpression. In vitro nitrosylation of cytochrome c increases caspase-3 activation in cell lysates. Moreover, the inhibition of intracellular cytochrome c nitrosylation is associated with a decrease in apoptosis, suggesting that cytochrome c nitrosylation is a proapoptotic modification. We conclude that nitrosylation of the heme iron of cytochrome c may be a novel mechanism of apoptosis regulation.

Acridine Orange↗