In Vivo Function of the Chaperonin TRiC in α-Actin Folding during Sarcomere Assembly.

The TCP-1 ring complex (TRiC) is a multi-subunit group II chaperonin that assists nascent or misfolded proteins to attain their native conformation in an ATP-dependent manner. Functional studies in yeast have suggested that TRiC is an essential and generalized component of the protein-folding machinery of eukaryotic cells. However, TRiC's involvement in specific cellular processes within multicellular organisms is largely unknown because little validation of TRiC function exists in animals.

Evaluation of exon-skipping strategies for Duchenne muscular dystrophy utilizing dystrophin-deficient zebrafish.

Duchenne muscular dystophy (DMD) is a severe muscle wasting disease caused by mutations in the dystrophin gene. By utilizing antisense oligonucleotides, splicing of the dystrophin transcript can be altered so that exons harbouring a mutation are excluded from the mature mRNA. Although this approach has been shown to be effective to restore partially functional dystrophin protein, the level of dystrophin protein that is necessary to rescue a severe muscle pathology has not been addressed.

The zebrafish dystrophic mutant softy maintains muscle fibre viability despite basement membrane rupture and muscle detachment.

The skeletal muscle basement membrane fulfils several crucial functions during development and in the mature myotome and defects in its composition underlie certain forms of muscular dystrophy. A major component of this extracellular structure is the laminin polymer, which assembles into a resilient meshwork that protects the sarcolemma during contraction. Here we describe a zebrafish mutant, softy, which displays severe embryonic muscle degeneration as a result of initial basement membrane failure.

Leukocyte tyrosine kinase functions in pigment cell development.

A fundamental problem in developmental biology concerns how multipotent precursors choose specific fates. Neural crest cells (NCCs) are multipotent, yet the mechanisms driving specific fate choices remain incompletely understood. Sox10 is required for specification of neural cells and melanocytes from NCCs.

Involvement of galanin receptors 1 and 2 in the modulation of mouse vagal afferent mechanosensitivity.

It is established that the gut peptide galanin reduces neuronal excitability via galanin receptor subtypes GALR1 and GALR3 and increases excitability via subtype GALR2. We have previously shown that galanin potently reduces mechanosensitivity in the majority of gastro-oesophageal vagal afferents, and potentiates sensitivity in a minority. These actions may have implications for therapeutic inhibition of gut afferent signalling.

The zebrafish candyfloss mutant implicates extracellular matrix adhesion failure in laminin alpha2-deficient congenital muscular dystrophy.

Mutations in the human laminin alpha2 (LAMA2) gene result in the most common form of congenital muscular dystrophy (MDC1A). There are currently three models for the molecular basis of cellular pathology in MDC1A: (i) lack of LAMA2 leads to sarcolemmal weakness and failure, followed by cellular necrosis, as is the case in Duchenne muscular dystrophy (DMD); (ii) loss of LAMA2-mediated signaling during the development and maintenance of muscle tissue results in myoblast proliferation and fusion defects; (iii) loss of LAMA2 from the basement membrane of the Schwann cells surrounding the peripheral nerves results in a lack of motor stimulation, leading to effective denervation atrophy. Here we show that the degenerative muscle phenotype in the zebrafish dystrophic mutant, candyfloss (caf) results from mutations in the laminin alpha2 (lama2) gene.

Galanin receptor-1 knockout mice exhibit spontaneous epilepsy, abnormal EEGs and altered inhibition in the hippocampus.

Galanin is a widely-distributed neuropeptide that acts as an endogenous anticonvulsant. We have recently generated a galanin receptor type 1 knockout mouse (Galr1(-/-)) that develops spontaneous seizures. Our aim here was to characterize the seizures by making electroencephalogram (EEG) recordings from this animal, and also to elucidate the cellular basis of its epileptic phenotype by studying the neurophysiology of CA1 pyramidal neurons in acute hippocampal slices.

Learning and memory performance in mice lacking the GAL-R1 subtype of galanin receptor.

The neuropeptide galanin induces performance deficits in a wide range of cognitive tasks in rodents. Three G-protein-coupled galanin receptor subtypes, designated GAL-R1, GAL-R2 and GAL-R3, have been cloned. The present study examined the role of GAL-R1 in cognition by testing mice with a null mutation in Galr1 on several different types of learning and memory tasks.

Altered hippocampal expression of neuropeptides in seizure-prone GALR1 knockout mice.

Purpose: Mice carrying a deletion of the GALR1 galanin receptor have recently showed spontaneous seizure phenotype with 25% penetrance. To better understand the role of neuropeptides, which are known to undergo complex plasticity changes with development of epileptic seizures, we characterized their expression in the hippocampal formation in GALR1- knockout (-KO) mice with or without seizures and in wild-type (WT) mice.

Methods: Immunohistochemistry and in situ hybridization were used to study expression of galanin, neuropeptide Y (NPY), substance P, enkephalin, dynorphin, and cholecystokinin (CCK).

Flexor reflex excitability in mice lacking galanin receptor galanin-R1.

This study was conducted to examine the excitability of the nociceptive flexor reflex and its sensitization by repetitive stimulation of C-fibers in anesthetized mice that lack the galanin-R1 receptor. Repetitive stimulation of C-fibers induced a gradual increase in reflex magnitude during the stimulation (wind-up), and a subsequent increase in spinal reflex excitability (central sensitization). This occurred in GAL-R1 -/-, GAL-R1 +/-, and +/+ wild-type controls, with no significant differences observed between genotypes.

Galanin GAL-R1 receptor null mutant mice display increased anxiety-like behavior specific to the elevated plus-maze.

The neuropeptide galanin coexists with norepinephrine and serotonin in neural systems mediating emotion. Previous findings suggested that galanin modulates anxiety-related behaviors in rodents. Three galanin receptor subtypes have been cloned; however, understanding their functions has been limited by the lack of galanin receptor subtype-selective ligands.

The second galanin receptor GalR2 plays a key role in neurite outgrowth from adult sensory neurons.

Expression of the neuropeptide galanin is markedly upregulated within the adult dorsal root ganglion (DRG) after peripheral nerve injury. We demonstrated previously that the rate of peripheral nerve regeneration is reduced in galanin knock-out mice, with similar deficits observed in neurite outgrowth from cultured mutant DRG neurons. Here, we show that the addition of galanin peptide significantly enhanced neurite outgrowth from wild-type sensory neurons and fully rescued the observed deficits in mutant cultures.

Critical role for GALR1 galanin receptor in galanin regulation of neuroendocrine function and seizure activity.

The GALR1 galanin receptor is expressed at high levels within the central nervous system. To determine which specific actions of galanin are mediated by GALR1, we have developed mice with an insertional inactivating mutation within the gene encoding GALR1 (Galr1). Homozygous Galr1-/- mice are viable and capable of breeding.