Association of cathepsin E deficiency with the increased territorial aggressive response of mice

Changes in Activity of Cysteine Cathepsins B and L in Brain Structures of Mice with Aggressive and Depressive-Like Behavior Formed under Conditions of Social Stress

We studied activity of lysosomal cysteine proteases, cathepsins B and L, in brain structures (frontal cortex, caudate nucleus, hippocampus, and hypothalamus) of C57Bl/6J mice with aggressive and depressive-like behavior formed under conditions of chronic social stress (repeated experience of victories and defeats within 20 days). Mice with depressive-like behavior showed increased activity of cathepsin В in the hypothalamus and nucleus caudatus and increased activity of cathepsin L in the hippocampus compared to control animals not subjected to agonistic confrontations. In mice with aggressive behavior, protease activity in the studied brain structures was not changed. In 4 h after immune system activation with LPS (250 μg/kg), cathepsin L activity in the hippocampus of control mice increased in comparison with mice receiving saline. In contrast to control animals, LPS caused a decrease in activity of the enzyme in the caudate nucleus and frontal cortex of aggressive mice and in the hippocampus of mice with depressive-like behavior.

Ginsenoside Re protects methamphetamine-induced dopaminergic neurotoxicity in mice via upregulation of dynorphin-mediated κ-opioid receptor and downregulation of substance P-mediated neurokinin 1 receptor

BACKGROUND

We previously reported that ginsenoside Re (GRe) attenuated against methamphetamine (MA)-induced neurotoxicity via anti-inflammatory and antioxidant potentials. We also demonstrated that dynorphin possesses anti-inflammatory and antioxidant potentials against dopaminergic loss, and that balance between dynorphin and substance P is important for dopaminergic neuroprotection. Thus, we examined whether GRe positively affects interactive modulation between dynorphin and substance P against MA neurotoxicity in mice.

METHODS

We examined changes in dynorphin peptide level, prodynorphin mRNA, and substance P mRNA, substance P-immunoreactivity, homeostasis in enzymatic antioxidant system, oxidative parameter, microglial activation, and pro-apoptotic parameter after a neurotoxic dose of MA to clarify the effects of GRe, prodynorphin knockout, pharmacological inhibition of κ-opioid receptor (i.e., nor-binaltorphimine), or neurokinin 1 (NK1) receptor (i.e., L-733,060) against MA insult in mice.

RESULTS

GRe attenuated MA-induced decreases in dynorphin level, prodynorphin mRNA expression in the striatum of wild-type (WT) mice. Prodynorphin knockout potentiated MA-induced dopaminergic toxicity in mice. The imbalance of enzymatic antioxidant system, oxidative burdens, microgliosis, and pro-apoptotic changes led to the dopaminergic neurotoxicity. Neuroprotective effects of GRe were more pronounced in prodynorphin knockout than in WT mice. Nor-binaltorphimine, a κ-opioid receptor antagonist, counteracted against protective effects of GRe. In addition, we found that GRe significantly attenuated MA-induced increases in substance P-immunoreactivity and substance P mRNA expression in the substantia nigra. These increases were more evident in prodynorphin knockout than in WT mice. Although, we observed that substance P-immunoreactivity was co-localized in NeuN-immunreactive neurons, GFAP-immunoreactive astrocytes, and Iba-1-immunoreactive microglia. NK1 receptor antagonist L-733,060 or GRe selectively inhibited microgliosis induced by MA. Furthermore, L-733,060 did not show any additive effects against GRe-mediated protective activity (i.e., antioxidant, antimicroglial, and antiapoptotic effects), indicating that NK1 receptor is one of the molecular targets of GRe.

CONCLUSIONS

Our results suggest that GRe protects MA-induced dopaminergic neurotoxicity via upregulatgion of dynorphin-mediated κ-opioid receptor and downregulation of substance P-mediated NK1 R.

Emerging roles of cathepsin E in host defense mechanisms

Cathepsin E is an intracellular aspartic proteinase of the pepsin superfamily, which is predominantly expressed in certain cell types, including the immune system cells and rapidly regenerating gastric mucosal and epidermal keratinocytes. The intracellular localization of this protein varies with different cell types. The endosomal localization is primarily found in antigen-presenting cells and gastric cells. The membrane association is observed with certain cell types such as erythrocytes, osteoclasts, gastric parietal cells and renal proximal tubule cells. This enzyme is also found in the endoplasmic reticulum, Golgi complex and cytosolic compartments in various cell types. In addition to its intracellular localization, cathepsin E occurs in the culture medium of activated phagocytes and cancer cells as the catalytically active enzyme. Its strategic expression and localization thus suggests the association of this enzyme with specific biological functions of the individual cell types. Recent genetic and pharmacological studies have particularly suggested that cathepsin E plays an important role in host defense against cancer cells and invading microorganisms. This review focuses emerging roles of cathepsin E in immune system cells and skin keratinocytes, and in host defense against cancer cells. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome.

A transcriptional network associated with natural variation in Drosophila aggressive behavior

A genome-wide screen of inbred Drosophila lines together with transcriptional network modeling reveals insights into the genetic bases of heritable aggression.

Background

Aggressive behavior is an important component of fitness in most animals. Aggressive behavior is genetically complex, with natural variation attributable to multiple segregating loci with allelic effects that are sensitive to the physical and social environment. However, we know little about the genes and genetic networks affecting natural variation in aggressive behavior. Populations of Drosophila melanogaster harbor quantitative genetic variation in aggressive behavior, providing an excellent model system for dissecting the genetic basis of naturally occurring variation in aggression.

Results

Correlating variation in transcript abundance with variation in complex trait phenotypes is a rapid method for identifying candidate genes. We quantified aggressive behavior in 40 wild-derived inbred lines of D. melanogaster and performed a genome-wide association screen for quantitative trait transcripts and single feature polymorphisms affecting aggression. We identified 266 novel candidate genes associated with aggressive behavior, many of which have pleiotropic effects on metabolism, development, and/or other behavioral traits. We performed behavioral tests of mutations in 12 of these candidate genes, and show that nine indeed affected aggressive behavior. We used the genetic correlations among the quantitative trait transcripts to derive a transcriptional genetic network associated with natural variation in aggressive behavior. The network consists of nine modules of correlated transcripts that are enriched for genes affecting common functions, tissue-specific expression patterns, and/or DNA sequence motifs.

Conclusions

Correlations among genetically variable transcripts that are associated with genetic variation in organismal behavior establish a foundation for understanding natural variation for complex behaviors in terms of networks of interacting genes.