Kinesin family member 2A gates nociception.

Nociceptive axons undergo remodeling as they innervate their targets during development and in response to environmental insults and pathological conditions. How is nociceptive morphogenesis regulated? Here, we show that the microtubule destabilizer kinesin family member 2A (Kif2a) is a key regulator of nociceptive terminal structures and pain sensitivity. Ablation of Kif2a in sensory neurons causes hyperinnervation and hypersensitivity to noxious stimuli in young adult mice, whereas touch sensitivity and proprioception remain unaffected. Computational modeling predicts that structural remodeling is sufficient to explain the phenotypes. Furthermore, Kif2a deficiency triggers a transcriptional response comprising sustained upregulation of injury-related genes and homeostatic downregulation of highly specific channels and receptors at the late stage. The latter effect can be predicted to relieve the hyperexcitability of nociceptive neurons, despite persisting morphological aberrations, and indeed correlates with the resolution of pain hypersensitivity. Overall, we reveal a critical control node defining nociceptive terminal structure, which is regulating nociception.

BILATERAL CRYPTORCHIDISM IN PEDIATRIC SURGEON'S PRACTICE: CURRENT TACTICS OF PATIENT MANAGEMENT.

OBJECTIVE: The aim: To provide best practices of disease management to improve treatment outcomes for this group of patients. PATIENTS AND METHODS: Materials and methods: The paper is based on first-hand experience in observing and treating 117 children aged from 6 months to 13 years with bilateral congenital cryptorchidism during a ten-year follow-up period, who were referred for surgical treatment, and 3 newborn boys with undescended testicles and testicular torsion. A complex of clinical and laboratory, instrumental, endocrinological, and genetic research methods was used for the survey of all patients. RESULTS: Results: Recognizing the action of a common causative factor for bilateral cryptorchidism, which is a consequence of primary endocrine disorders, makes it possible to predict bilateral identity of the location of testicles in this pathology, which we observed in 81 patients: bilateral inguinal cryptorchidism was registered in 49 (41.88%) children, bilateral abdominal cryptorchidism - in 32 (27.35%) children, a combination of inguinal and abdominal cryptorchidism - in 24 (20.51%) children. The following types of treatment were used in the studied group of children: 1 - primary surgical intervention - 4 children, representing 3.42%. 2 - observation and non-surgical treatment by an endocrinologist - 113 (96.58%) children. 3 - comprehensive treatment (surgical correction after hormone treatment) - 67 (59.29%) children. According to the research, hormone therapy had a positive effect on descent of the testicles in 89 (78.76%) patients: the testicles descended into the scrotum - in 22 (24.72%) children; the testicles descended in the inguinal canal - in 32 (35.95%) children; the testicles descended to the level of the opening to the inguinal canal - in 35 (39.33%) children. CONCLUSION: Conclusions: 1. All doctors, starting from the maternity hospital, polyclinic, children's unit, should identify children with bilateral cryptorchidism. All children diagnosed with bilateral cryptorchidism are referred to a surgeon or endocrinologist. The parents of a child with bilateral cryptorchidism should immediately consult a doctor. The study of the reasons for late admission of children to the surgical hospital revealed that 76.92% of patients sought medical advice late, after 1 year of life. 2. At the stage of diagnosis and determination of treatment tactics, an examination by an endocrinologist and a geneticist is necessary; ignoring them is considered an error in diagnostic and therapeutic tactics, since the process of descent of the testicles into the scrotum is hormone-dependent. 3. The indications for primary surgical treatment of a child with bilateral cryptorchidism involve a combination of cryptorchidism with inguinal hernia and pain syndrome, which might be caused by testicular torsion. 4. Hormone therapy provides better results of surgical intervention in bilateral cryptorchidism. The ineffectiveness of two courses of hormone therapy necessitates surgical treatment. 5. Comprehensive treatment of children with bilateral cryptorchidism (non-surgical hormone therapy and surgical correction) has led to good postoperative results in 71.64% of patients, satisfactory results - in 22.39% of children, recurrences - in 5.97% of patients. 7. A long-term follow-up observation should be carried out by a surgeon and endocrinologist until patients reach their reproductive years.

Cracking the combinatorial code of neuronal wiring.

How transcription factors orchestrate the combinatorial expression of cell-surface proteins that, in turn, specify the wiring of the nervous system is an open question. In this issue of Neuron, Xie et al. reveal a new, unexpected layer of complexity.

Performance Degradations of MISFET-Based Hydrogen Sensors with a Pd-Ta2O5-SiO2-Si Structure During Long-Term Operation.

We present the generalized experimental results of performance degradation of hydrogen sensors based on metal-insulator-semiconductor field effect transistor (MISFET)with the structure Pd-Ta2O5-SiO2-Si. The n-channel MISFET elements were fabricated on silicon single chips together with temperature sensors and heater-resistors by means of conventional -technology. Two hundred cycles of responses to different hydrogen concentrations were measured during eight weeks using special measuring and temperature stabilization circuitries with a feedback loop based on the chip's thermo-sensor and heater. We show how the response parameters change during long-term tests of sensors under repeated hydrogen impacts. There were two stages of time-dependent response instability, the degradation of which depends on operating conditions, hydrogen concentrations, and time. To interpret results, we proposed the models, parameters of which were calculated using experimental data. These models can be used to predict performances of MISFET-based gas analysis devices for long-term operation.

Caspase-8 deficiency in mouse embryos triggers chronic RIPK1-dependent activation of inflammatory genes, independently of RIPK3.

Deletion of the Casp8 gene in epithelial tissues of mice results in severe inflammatory pathologies. Its ubiquitous deletion, or its specific deletion in endothelial cells, results in intrauterine death associated with capillary damage. These pathologies are all preventable by co-deletion of Casp8 and the genes encoding either the RIPK1 or the RIPK3 protein kinase. Since activation of RIPK3 in Caspase-8-deficient cells can trigger necroptotic cell death, and since RIPK1 can activate RIPK3, it is widely assumed that the inflammatory states resulting from Caspase-8 deficiency occur as a consequence of RIPK3-induced necroptosis. Here, we report that although on a Ripk3-null background Casp8 deletion in mice does not result in outright pathological changes, it triggers enhanced expression of a variety of inflammatory genes in utero, which gradually subsides after birth. Deletion of Ripk1, or even of only one of its two alleles, obliterates this activation. Resembling the embryonic pathology observed in RIPK3-expressing cells, the activation of inflammatory genes observed on a Ripk3-null background seems to be initiated in endothelial cells. Analysis of endothelial cells isolated from livers of Caspase-8-deficient embryos revealed neither an increase in the amount of RIPK1 in these cells after Casp8 deletion, nor triggering of RIPK1 phosphorylation. These findings indicate that the triggering of inflammation by Casp8 deletion in mice occurs, in part, independently of necroptosis or other functions of RIPK3, and rather reflects enhanced RIPK1-dependent signaling for activation of inflammatory genes.

MLKL, the Protein that Mediates Necroptosis, Also Regulates Endosomal Trafficking and Extracellular Vesicle Generation.

Activation of the pseudokinase mixed lineage kinase domain-like (MLKL) upon its phosphorylation by the protein kinase RIPK3 triggers necroptosis, a form of programmed cell death in which rupture of cellular membranes yields release of intracellular components. We report that MLKL also associated with endosomes and controlled the transport of endocytosed proteins, thereby enhancing degradation of receptors and ligands, modulating their induced signaling and facilitating the generation of extracellular vesicles. This role was exerted on two quantitative grades: a constitutive one independent of RIPK3, and an enhanced one, triggered by RIPK3, where the association of MLKL with the endosomes was enhanced, and it was found to bind endosomal sorting complexes required for transport (ESCRT) proteins and the flotillins and to be excluded, together with them, from cells within vesicles. We suggest that release of phosphorylated MLKL within extracellular vesicles serves as a mechanism for self-restricting the necroptotic activity of this protein.

Activation of the NLRP3 inflammasome by proteins that signal for necroptosis.

Necroptosis-a form of programmed necrotic cell death-and its resulting release of damage-associated molecular patterns (DAMPs) are believed to participate in the triggering of inflammatory processes. To assess the relative contribution of this cell death mode to inflammation, we need to know what other cellular effects can be exerted by molecules shown to trigger necrotic death, and the extent to which those effects might themselves contribute to inflammation. Here, we describe the technical approaches that have been applied to assess the impact of the main signaling molecules known to mediate activation of necroptosis upon generation of inflammatory cytokines in LPS-treated mouse bone marrow-derived dendritic cells. The findings obtained by this assessment indicated that signaling molecules known to initiate necroptosis can also initiate activation of the NLRP3 inflammasome, thereby inducing inflammation independently of cell death by triggering the generation of proinflammatory cytokines such as IL-1ß.

Keeping inflammation at bay.

Cells dying by apoptosis can trigger an anti-inflammatory gene response in other cells by releasing a compound called adenosine monophosphate.

The in vivo significance of necroptosis: lessons from exploration of caspase-8 function.

Emerging evidence indicates that necrotic cell death can be regulated by a specific set of signaling molecules. Studies showing that the same signaling molecules also trigger inflammation, and that when cells die necrotically some of the molecules they release facilitate inflammation, raised the possibility that the death induced by these signaling molecules ("necroptosis") serves to trigger inflammation. Here we briefly discuss the work done on the anti-inflammatory function of caspase-8 and its relation to the inhibitory effect of this enzyme on the induction of necroptosis. The studies imply that caspase-8 and the other proximal signaling proteins known to participate in the induction and regulation of necroptosis are too pleiotropic to serve as reliable molecular probes for determining the relative contribution of this death mode to in vivo processes.

Concepts of tissue injury and cell death in inflammation: a historical perspective.

Emerging evidence indicates that the molecular mechanisms of cell death have regulatory roles in inflammation and that the molecular changes that are associated with different forms of cell death affect the course of inflammation in different ways. In this Timeline article, we discuss how our understanding of the mechanisms and functional roles of tissue injury and cell death in inflammation has evolved on the basis of almost two centuries of study. We describe how such ideas have led to our current models of cell death and inflammation, and we highlight the remaining gaps in our knowledge of the subject.

How do cells sense foreign DNA? A new outlook on the function of STING.

STING, a protein mediating signaling activation by cytosolic DNA and known to act downstream of DNA sensor proteins, is shown also to bind DNA directly, raising the need to clarify the relative contributions of these distinct binding modes to DNA sensing.

Phosphorylation and dephosphorylation of the RIG-I-like receptors: a safety latch on a fateful pathway.

Activation of antiviral responses by RNA sensors RIG-I and MDA5 must be stringently controlled. In this issue of Immunity, Wies et al. (2013) show that a requirement for activation-induced dephosphorylation of these proteins reinforces this restriction.

Caspase-8 blocks kinase RIPK3-mediated activation of the NLRP3 inflammasome.

Caspase-8 deficiency in certain cells prompts chronic inflammation. One mechanism suggested to account for this inflammation is enhanced signaling for necrotic cell death, mediated by the protein kinases RIPK1 and RIPK3 that caspase-8 can cleave. We describe an activity of caspase-8 in dendritic cells that controls the initiation of inflammation in another way. Caspase-8 deficiency in these cells facilitated lipopolysaccharide-induced assembly and function of the NLRP3 inflammasome. This effect depended on the functions of RIPK1 and RIPK3, as well as of MLKL and PGAM5, two signaling proteins recently shown to contribute to RIPK3-mediated induction of necrosis. However, although enhancement of inflammasome assembly in the caspase-8-deficient cells shares proximal signaling events with the induction of necrosis, it occurred independently of cell death. These findings provide new insight into potentially pathological inflammatory processes to which RIPK1- and RIPK3-mediated signaling contributes.

'Necrosome'-induced inflammation: must cells die for it?

Necrosis, a form of death characterized by rupture of the cell membrane, is closely interlinked with inflammation. Cellular components released during necrotic death can trigger inflammation. Conversely, inflammation often yields tissue damage and, as a consequence, cell death. Which occurs first--necrosis or inflammation--in specific in vivo situations is currently difficult to tell. A way out of this 'chicken-and-egg' conundrum may be found via the recent finding that both necrotic cell death and inflammation can be initiated by a distinct set of signaling proteins, the 'necrosome', that includes receptor-interacting protein (RIP)1, RIP3 and caspase-8. Further clarifying the function of these signaling proteins should make it possible to establish when they induce inflammation directly and when inflammation is caused by necrotic cell death.

RIG-I RNA helicase activation of IRF3 transcription factor is negatively regulated by caspase-8-mediated cleavage of the RIP1 protein.

Excessive responses to pattern-recognition receptors are prevented by regulatory mechanisms that affect the amounts and activities of the downstream signaling proteins. We report that activation of the transcription factor IRF3 by the ribonucleic acid sensor RIG-I was restricted by caspase-8-mediated cleavage of the RIP1 protein, which resulted in conversion of RIP1 from a signaling enhancer to a signaling inhibitor. The proteins RIP1 and caspase-8 were recruited to the RIG-I complex after viral infection and served antagonistic regulatory roles. Conjugation of ubiquitin chains to RIP1 facilitated assembly of the RIG-I complex, resulting in enhanced phosphorylation of IRF3. However, the ubiquitination of RIP1 also rendered it susceptible to caspase-8-mediated cleavage that yielded an inhibitory RIP1 fragment. The dependence of RIP1 cleavage on the same molecular change as that facilitating RIG-I signaling allows for RIG-I signaling to be restricted in its duration without compromising its initial activation.

Anti-inflammatory functions of the "apoptotic" caspases.

The two main known functions of the caspases act antagonistically in regulating inflammation. "Inflammatory" caspases trigger inflammation by catalyzing the processing of IL-1ß precursors and other proinflammatory cytokines. In contrast, "apoptotic" caspases safeguard against the triggering of inflammation by imposing a cell-death form that withholds release of alarmins by dying cells and dictates generation of anti-inflammatory mediators. These antagonizing functions are exerted by evolution-related mechanisms. Studies of the function of caspase-8, an enzyme-mediating apoptotic cell-death induction in response to TNF-family ligands, reveal that it blocks inflammation in additional ways. One way is by restricting activation of the RIG-I complex by foreign ribonucleic acid. Chronic skin inflammation in mice with caspase-8-deficient epidermis is associated with constitutive activation of the RIG-I complex in keratinocytes. This activation is apparently prompted by nucleic acids released from epidermal cells that disintegrate during cornification, and becomes chronic because it is not restricted by caspase-8.

Caspase-8 deficiency in epidermal keratinocytes triggers an inflammatory skin disease.

Expression of enzymatically inactive caspase-8, or deletion of caspase-8 from basal epidermal keratinocytes, triggers chronic skin inflammation in mice. Unlike similar inflammation resulting from arrest of nuclear factor kappaB activation in the epidermal cells, the effect induced by caspase-8 deficiency did not depend on TNF, IL-1, dermal macrophage function, or expression of the toll-like receptor adapter proteins MyD88 or TRIF. Both interferon regulatory factor (IRF) 3 and TANK-binding kinase were constitutively phosphorylated in the caspase-8-deficient epidermis, and knockdown of IRF3 in the epidermis-derived cells from these mice abolished the expression of up-regulated genes. Temporal and spatial analyses of the alterations in gene expression that result from caspase-8 deficiency reveal that the changes are initiated before birth, around the time that cornification develops, and occur mainly in the suprabasal layer. Finally, we found that caspase-8-deficient keratinocytes display an enhanced response to gene activation by transfected DNA. Our findings suggest that an enhanced response to endogenous activators of IRF3 in the epidermis, presumably generated in association with keratinocyte differentiation, contributes to the skin inflammatory process triggered by caspase-8 deficiency.

12th international TNF conference: the good, the bad and the scientists.

Members of the TNF superfamily control numerous aspects of immune defense as well as various processes of homeostasis and embryonic development. Recent advances in our knowledge of both the beneficial and the deleterious activities of these cytokines were thoroughly discussed at this conference. Participants presented new information about signaling mechanisms that these cytokines activate, with special attention to cell-death regulation, ubiquitination of signaling-proteins as a means of regulating their function, and complex systems of gene and signaling regulation. Sessions were devoted specifically to aberrations in functions of the TNF-family that contribute to the pathology of infectious, autoimmune and neurodegenerative diseases and to cancer, and to the application of our knowledge to therapy.