Two-dimensional gene expression fingerprinting

Upregulation of SLITRK5 in patients with epilepsy and in a rat model

SLIT and NTRK-like protein-5 (SLITRK5) is one of the six members of SLITRK protein family, which is widely expressed in central nervous system (CNS). In brain, SLITRK5 plays important roles in neurite outgrowth, dendritic branching, neuron differentiation, synaptogenesis, and signal transmission of neurons. Epilepsy is a common, chronic neurological disorder characterized by recurrent spontaneous seizures. The pathophysiological mechanism of epilepsy remains unclear. Neuronal apoptosis, abnormal nerve excitatory transmission, and synaptic remodeling are thought to be involved in the development of epilepsy. To explore whether there is a potential relationship between SLITRK5 and epilepsy, we investigated the expression and distribution of SLITRK5 in patients with temporal lobe epilepsy (TLE) and a rat model of epilepsy. We collected cerebral cortex samples from patients with drug-refractory temporal lobe epilepsy, and a rat model of epilepsy induced by lithium chloride/pilocarpine was established. The ways of immunohistochemistry, double-immunofluorescence labeling and western blot have been used in our study to research the expression and distribution of SLITRK5 in the temporal lobe epilepsy patients and epilepsy animal model. All of the results have shown that SLITRK5 is mainly localized in the cell cytoplasm of neurons both in patients with TLE and in epilepsy model. In addition, compared with nonepileptic controls, the expression of SLITRK5 was upregulated in the temporal neocortex of TLE patients. And both in the temporal neocortex and hippocampus of pilocarpine-induced epilepsy rats, the expression of SLITRK5 was increased at 24 h after status epilepticus (SE), with a relatively high level within 30 days, and reached the peak on the 7th day after SE. Our preliminary results revealed that SLITRK5 may have a potential relationship with epilepsy, which may be a foundation for the further study of the underlying mechanism between SLITRK5 and epilepsy and the therapeutic targets of antiepileptic drugs.

The Role of SliTrk5 in Central Nervous System

SLIT and NTRK-like protein-5 (SliTrk5) is one of the six members of SliTrk protein family, which is widely expressed in the central nervous system (CNS), regulating and participating in many essential steps of central nervous system development, including axon and dendritic growth, neuron differentiation, and synaptogenesis. SliTrk5, as a neuron transmembrane protein, contains two important conservative domains consisting of leucine repeats (LRRs) located at the amino terminal in the extracellular region and tyrosine residues (Tyr) located at the carboxyl terminal in the intracellular domains. These special structures make SliTrk5 play an important role in the pathological process of the CNS. A large number of studies have shown that SliTrk5 may be involved in the pathogenesis of CNS diseases, such as obsessive-compulsive-disorder (OCD), attention deficit/hyperactivity disorder (ADHD), glioma, autism spectrum disorders (ASDs), and Parkinson's disease (PD). Targeting SliTrk5 is expected to become a new target for the treatment of CNS diseases, promoting the functional recovery of CNS. The purpose of this article is to review the current research progression of the role of SliTrk5 in CNS and its potential mechanisms in CNS diseases.

Slitrks as emerging candidate genes involved in neuropsychiatric disorders

Slitrks are a family of structurally related transmembrane proteins belonging to the leucine-rich repeat (LRR) superfamily. Six family members exist (Slitrk1-6) and all are highly expressed in the central nervous system (CNS). Slitrks have been implicated in mediating basic neuronal processes, ranging from neurite outgrowth and dendritic elaboration to neuronal survival. Recent studies in humans and genetic mouse models have led to the identification of Slitrks as candidate genes that might be involved in the development of neuropsychiatric conditions, such as obsessive compulsive spectrum disorders and schizophrenia. Although these system-level approaches have suggested that Slitrks play prominent roles in CNS development, key questions remain regarding the molecular mechanisms through which they mediate neuronal signaling and connectivity.

Slitrk5 deficiency impairs corticostriatal circuitry and leads to obsessive-compulsive-like behaviors in mice

Obsessive-compulsive disorder (OCD) is a common psychiatric disorder defined by the presence of obsessive thoughts and repetitive compulsive actions, and it often encompasses anxiety and depressive symptoms. Recently, the corticostriatal circuitry has been implicated in the pathogenesis of OCD. However, the etiology, pathophysiology and molecular basis of OCD remain unknown. Several studies indicate that the pathogenesis of OCD has a genetic component. Here we demonstrate that loss of a neuron-specific transmembrane protein, SLIT and NTRK-like protein-5 (Slitrk5), leads to OCD-like behaviors in mice, which manifests as excessive self-grooming and increased anxiety-like behaviors, and is alleviated by the selective serotonin reuptake inhibitor fluoxetine. Slitrk5(-/-) mice show selective overactivation of the orbitofrontal cortex, abnormalities in striatal anatomy and cell morphology and alterations in glutamate receptor composition, which contribute to deficient corticostriatal neurotransmission. Thus, our studies identify Slitrk5 as an essential molecule at corticostriatal synapses and provide a new mouse model of OCD-like behaviors.

Jedi—a novel transmembrane protein expressed in early hematopoietic cells

Self-renewal and differentiation of hematopoietic stem and progenitor cells are defined by the ensembles of genes expressed by these cells. Here we report identification of a novel gene named Jedi, which is expressed predominantly in short- and long-term repopulating stem cells when compared to more mature bone marrow progenitors. Jedi mRNA encodes a transmembrane protein that contains multiple EGF-like repeats. Jedi and two earlier reported proteins, MEGF10 and MEGF11, share a substantial homology and are likely to represent a novel protein family. Studies of the potential role of Jedi in hematopoietic regulation demonstrated that the retrovirally mediated expression of Jedi in bone marrow cells decreased the number of myeloid progenitors in in vitro clonogenic assays. In addition, expression of Jedi in NIH 3T3 fibroblasts resulted in a decreased number of late and early myeloid progenitors in the non-adherent co-cultured bone marrow cells. Jedi shares a number of structural features with the Jagged/Serrate/Delta family of Notch ligands, and our experiments indicate that the extracellular domain of Jedi, similar to the corresponding domain of Jagged1, inhibits Notch signaling. On the basis of obtained results, we suggest that Jedi is involved in the fine regulation of the early stages of hematopoietic differentiation, presumably through the Notch signaling pathway.