Kon-tiki enhances PS2 integrin adhesion and localizes its ligand, Thrombospondin, in the myotendinous junction.

Cell-extracellular-matrix adhesion is mediated by cell receptors, mainly integrins and transmembrane proteoglycans, which can functionally interact. How these receptors are regulated and coordinated is largely unknown. We show that the conserved transmembrane Drosophila proteoglycan Kon-tiki (Kon, also known as Perdido) interacts with the αPS2ßPS integrin (αPS2 is encoded by inflated and ßPS by myospheroid) to mediate muscle-tendon adhesion. kon and inflated double mutant embryos show a synergistic increase in muscle detachment. Furthermore, Kon modulates αPS2ßPS signaling at the muscle attachment, since phosphorylated Fak is reduced in kon mutants. This reduction in integrin signaling can be rescued by the expression of a truncated Kon protein containing its transmembrane and extracellular domains, suggesting that these domains are sufficient to mediate this signaling. We show that these domains are sufficient to properly localize the αPS2ßPS ligand, Thrombospondin, to the muscle attachment, and to partially rescue Kon-dependent muscle-tendon adhesion. We propose that Kon can engage in a protein complex with αPS2ßPS and enhance integrin-mediated signaling and adhesion by recruiting its ligand, which would increase integrin-binding affinity to the extracellular matrix, resulting in the consolidation of the myotendinous junction.

The conserved transmembrane proteoglycan Perdido/Kon-tiki is essential for myofibrillogenesis and sarcomeric structure in Drosophila.

Muscle differentiation requires the assembly of high-order structures called myofibrils, composed of sarcomeres. Even though the molecular organization of sarcomeres is well known, the mechanisms underlying myofibrillogenesis are poorly understood. It has been proposed that integrin-dependent adhesion nucleates myofibrils at the periphery of the muscle cell to sustain sarcomere assembly. Here, we report a role for the gene perdido (perd, also known as kon-tiki, a transmembrane chondroitin proteoglycan) in myofibrillogenesis. Expression of perd RNAi in muscles, prior to adult myogenesis, can induce misorientation and detachment of Drosophila adult abdominal muscles. In comparison to controls, perd-depleted muscles contain fewer myofibrils, which are localized at the cell periphery. These myofibrils are detached from each other and display a defective sarcomeric structure. Our results demonstrate that the extracellular matrix receptor Perd has a specific role in the assembly of myofibrils and in sarcomeric organization. We suggest that Perd acts downstream or in parallel to integrins to enable the connection of nascent myofibrils to the Z-bands. Our work identifies the Drosophila adult abdominal muscles as a model to investigate in vivo the mechanisms behind myofibrillogenesis.

Microglia mitochondrial complex I deficiency during development induces glial dysfunction and early lethality.

Primary mitochondrial diseases (PMDs) are associated with pediatric neurological disorders and are traditionally related to oxidative phosphorylation system (OXPHOS) defects in neurons. Interestingly, both PMD mouse models and patients with PMD show gliosis, and pharmacological depletion of microglia, the innate immune cells of the brain, ameliorates multiple symptoms in a mouse model. Given that microglia activation correlates with the expression of OXPHOS genes, we studied whether OXPHOS deficits in microglia may contribute to PMDs. We first observed that the metabolic rewiring associated with microglia stimulation in vitro (via IL-33 or TAU treatment) was partially changed by complex I (CI) inhibition (via rotenone treatment). In vivo, we generated a mouse model deficient for CI activity in microglia (MGcCI). MGcCI microglia showed metabolic rewiring and gradual transcriptional activation, which led to hypertrophy and dysfunction in juvenile (1-month-old) and adult (3-month-old) stages, respectively. MGcCI mice presented widespread reactive astrocytes, a decrease of synaptic markers accompanied by an increased number of parvalbumin neurons, a behavioral deficit characterized by prolonged periods of immobility, loss of weight and premature death that was partially rescued by pharmacologic depletion of microglia. Our data demonstrate that microglia development depends on mitochondrial CI and suggest a direct microglial contribution to PMDs.

The therapeutic relationship from the perspective of patients and nurses in the first days of admission: A cross-sectional study in acute mental health units.

The therapeutic relationship (TR) is essential in mental health nursing care and plays a fundamental role in the understanding and treatment of the patient's health status. Despite being a bidirectional construct, limited evidence is available to shed light on this issue in mental health units and even less so in the first days of admission. This study aimed to examine the association and differences between nurses' and patients' perspectives on the establishment of the therapeutic relationship in acute mental health units during the first days of hospitalization. A cross-sectional study was carried out in 12 Spanish mental health units. Data were collected from patients and nurses using the Working Alliance Inventory-Short (WAI-S) questionnaire. A total of 234 cases were analysed, including 234 patients and 58 nurses. The results showed a positive association between nurses' and patients' perspectives on the therapeutic relationship, but also revealed significant differences on each WAI-S dimension. Nurses assigned higher scores compared to patients on the perception of the quality of the therapeutic relationship. The dimensions with the greatest weight from the patients' perspective regarding the quality of the therapeutic relationship were the perception of greater agreement on goals and tasks among nurses. This study demonstrates the importance of establishing shared goals and tasks with nurses from the first days of hospitalization to improve the quality of the therapeutic relationship as perceived by patients. These findings underline the need to consider the different perspectives of both parties to promote a high-quality therapeutic relationship.

GAL4 Drivers Specific for Type Ib and Type Is Motor Neurons in Drosophila.

The Drosophila melanogaster larval neuromuscular system is extensively used by researchers to study neuronal cell biology, and Drosophila glutamatergic motor neurons have become a major model system. There are two main Types of glutamatergic motor neurons, Ib and Is, with different structural and physiological properties at synaptic level at the neuromuscular junction. To generate genetic tools to identify and manipulate motor neurons of each Type, we screened for GAL4 driver lines for this purpose. Here we describe GAL4 drivers specific for examples of neurons within each Type, Ib or Is. These drivers showed high expression levels and were expressed in only few motor neurons, making them amenable tools for specific studies of both axonal and synapse biology in identified Type I motor neurons.