Piezo1 agonist restores meningeal lymphatic vessels, drainage, and brain-CSF perfusion in craniosynostosis and aged mice.

Skull development coincides with the onset of cerebrospinal fluid (CSF) circulation, brain-CSF perfusion, and meningeal lymphangiogenesis, processes essential for brain waste clearance. How these processes are affected by craniofacial disorders such as craniosynostosis are poorly understood. We report that raised intracranial pressure and diminished CSF flow in craniosynostosis mouse models associate with pathological changes to meningeal lymphatic vessels that affect their sprouting, expansion, and long-term maintenance.

Understanding the development, pathogenesis, and injury response of meningeal lymphatic networks through the use of animal models.

Meningeal lymphatic vessels (MLVs) help maintain central nervous system (CNS) homeostasis via their ability to facilitate macromolecule waste clearance and neuroimmune trafficking. Although these vessels were overlooked for centuries, they have now been characterized in humans, non-human primates, and rodents. Recent studies in mice have explored the stereotyped growth and expansion of MLVs in dura mater, the various transcriptional, signaling, and environmental factors regulating their development and long-term maintenance, and the pathological changes these vessels undergo in injury, disease, or with aging.

Piezo1 agonist restores meningeal lymphatic vessels, drainage, and brain-CSF perfusion in craniosynostosis and aged mice.

Skull development coincides with the onset of cerebrospinal fluid (CSF) circulation, brain-CSF perfusion, and meningeal lymphangiogenesis, processes essential for brain waste clearance. How these processes are affected by craniofacial disorders such as craniosynostosis are poorly understood. We report that raised intracranial pressure and diminished CSF flow in craniosynostosis mouse models associates with pathological changes to meningeal lymphatic vessels that affect their sprouting, expansion, and long-term maintenance.

Loss of Twist1 and balanced retinoic acid signaling from the meninges causes cortical folding in mice.

Secondary lissencephaly evolved in mice due to effects on neurogenesis and the tangential distribution of neurons. Signaling pathways that help maintain lissencephaly are still poorly understood. We show that inactivating Twist1 in the primitive meninges causes cortical folding in mice.

Mapping the neuroethological signatures of pain, analgesia, and recovery in mice.

Ongoing pain is driven by the activation and modulation of pain-sensing neurons, affecting physiology, motor function, and motivation to engage in certain behaviors. The complexity of the pain state has evaded a comprehensive definition, especially in non-verbal animals. Here, in mice, we used site-specific electrophysiology to define key time points corresponding to peripheral sensitivity in acute paw inflammation and chronic knee pain models.

Cranium growth, patterning and homeostasis.

Craniofacial development requires precise spatiotemporal regulation of multiple signaling pathways that crosstalk to coordinate the growth and patterning of the skull with surrounding tissues. Recent insights into these signaling pathways and previously uncharacterized progenitor cell populations have refined our understanding of skull patterning, bone mineralization and tissue homeostasis. Here, we touch upon classical studies and recent advances with an emphasis on developmental and signaling mechanisms that regulate the osteoblast lineage for the calvaria, which forms the roof of the skull.

TWIST1, a gene associated with Saethre-Chotzen syndrome, regulates extraocular muscle organization in mouse.

Heterozygous loss of function mutations in TWIST1 cause Saethre-Chotzen syndrome, which is characterized by craniosynostosis, facial asymmetry, ptosis, strabismus, and distinctive ear appearance. Individuals with syndromic craniosynostosis have high rates of strabismus and ptosis, but the underlying pathology is unknown. Some individuals with syndromic craniosynostosis have been noted to have absence of individual extraocular muscles or abnormal insertions of the extraocular muscles on the globe.

Planar cell polarity and the pathogenesis of Tourette Disorder: New hypotheses and perspectives.

Planar cell polarity (PCP) signaling plays a fundamental role in shaping the development and ongoing function of the nervous system, beginning from early stages of neural tube closure and spanning the maintenance of functional synapses in adults. While mutations in core PCP signaling proteins have long been suspected to underlie neural tube closure defects in humans, recent findings also implicate their potential involvement in neurodevelopmental and neuropsychiatric disorders. Missense and loss-of-function mutations in CELSR3, a core component of PCP signaling complexes, are highly associated with Tourette Disorder.

The growth and expansion of meningeal lymphatic networks are affected in craniosynostosis.

Skull malformations are associated with vascular anomalies that can impair fluid balance in the central nervous system. We previously reported that humans with craniosynostosis and mutations in TWIST1 have dural venous sinus malformations. It is still unknown whether meningeal lymphatic networks, which are patterned alongside the venous sinuses, are also affected.

Recurrent Implication of Striatal Cholinergic Interneurons in a Range of Neurodevelopmental, Neurodegenerative, and Neuropsychiatric Disorders.

Cholinergic interneurons are "gatekeepers" for striatal circuitry and play pivotal roles in attention, goal-directed actions, habit formation, and behavioral flexibility. Accordingly, perturbations to striatal cholinergic interneurons have been associated with many neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. The role of acetylcholine in many of these disorders is well known, but the use of drugs targeting cholinergic systems fell out of favor due to adverse side effects and the introduction of other broadly acting compounds.

Neuronal-Specific TUBB3 Is Not Required for Normal Neuronal Function but Is Essential for Timely Axon Regeneration.

We generated a knockout mouse for the neuronal-specific β-tubulin isoform Tubb3 to investigate its role in nervous system formation and maintenance. Tubb3 mice have no detectable neurobehavioral or neuropathological deficits, and upregulation of mRNA and protein of the remaining β-tubulin isotypes results in equivalent total β-tubulin levels in Tubb3 and wild-type mice. Despite similar levels of total β-tubulin, adult dorsal root ganglia lacking TUBB3 have decreased growth cone microtubule dynamics and a decreased neurite outgrowth rate of 22% in vitro and in vivo.

Ocular Motor Nerve Development in the Presence and Absence of Extraocular Muscle.

Purpose: To spatially and temporally define ocular motor nerve development in the presence and absence of extraocular muscles (EOMs).

Methods: Myf5cre mice, which in the homozygous state lack EOMs, were crossed to an IslMN:GFP reporter line to fluorescently label motor neuron cell bodies and axons. Embryonic day (E) 11.

Transient Opening of the Mitochondrial Permeability Transition Pore Induces Microdomain Calcium Transients in Astrocyte Processes.

Astrocytes extend highly branched processes that form functionally isolated microdomains, facilitating local homeostasis by redistributing ions, removing neurotransmitters, and releasing factors to influence blood flow and neuronal activity. Microdomains exhibit spontaneous increases in calcium (Ca), but the mechanisms and functional significance of this localized signaling are unknown. By developing conditional, membrane-anchored GCaMP3 mice, we found that microdomain activity that occurs in the absence of inositol triphosphate (IP3)-dependent release from endoplasmic reticulum arises through Ca efflux from mitochondria during brief openings of the mitochondrial permeability transition pore.

Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects.

Duane retraction syndrome (DRS) is a congenital eye-movement disorder defined by limited outward gaze and retraction of the eye on attempted inward gaze. Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness. Using genotype-phenotype correlations in humans and Mafb-knockout mice, we propose a threshold model for variable loss of MAFB function.

Two unique TUBB3 mutations cause both CFEOM3 and malformations of cortical development.

One set of missense mutations in the neuron specific beta tubulin isotype 3 (TUBB3) has been reported to cause malformations of cortical development (MCD), while a second set has been reported to cause isolated or syndromic Congenital Fibrosis of the Extraocular Muscles type 3 (CFEOM3). Because TUBB3 mutations reported to cause CFEOM had not been associated with cortical malformations, while mutations reported to cause MCD had not been associated with CFEOM or other forms of paralytic strabismus, it was hypothesized that each set of mutations might alter microtubule function differently. Here, however, we report two novel de novo heterozygous TUBB3 amino acid substitutions, G71R and G98S, in four patients with both MCD and syndromic CFEOM3.

Canonical WNT signaling components in vascular development and barrier formation.

Canonical WNT signaling is required for proper vascularization of the CNS during embryonic development. Here, we used mice with targeted mutations in genes encoding canonical WNT pathway members to evaluate the exact contribution of these components in CNS vascular development and in specification of the blood-brain barrier (BBB) and blood-retina barrier (BRB). We determined that vasculature in various CNS regions is differentially sensitive to perturbations in canonical WNT signaling.

An inherited TUBB2B mutation alters a kinesin-binding site and causes polymicrogyria, CFEOM and axon dysinnervation.

Microtubules are essential components of axon guidance machinery. Among β-tubulin mutations, only those in TUBB3 have been shown to cause primary errors in axon guidance. All identified mutations in TUBB2B result in polymicrogyria, but it remains unclear whether TUBB2B mutations can cause axon dysinnervation as a primary phenotype.

Phenotypic spectrum of the tubulin-related disorders and functional implications of disease-causing mutations.

A spectrum of neurological disorders characterized by abnormal neuronal migration, differentiation, and axon guidance and maintenance have recently been attributed to missense and splice-site mutations in the genes that encode α-tubulin and β-tubulin isotypes TUBA1A, TUBA8, TUBB2B, and TUBB3, all of which putatively coassemble into neuronal microtubules. The resulting nervous system malformations can include different types of cortical malformations, defects in commissural fiber tracts, and degeneration of motor and sensory axons. Many clinical phenotypes and brain malformations are shared among the various mutations regardless of structural location and/or isotype, while others segregate with distinct amino acids or functional domains within tubulin.

Distinct alpha- and beta-tubulin isotypes are required for the positioning, differentiation and survival of neurons: new support for the 'multi-tubulin' hypothesis.

The many functions of the microtubule cytoskeleton are essential for shaping the development and maintaining the operation of the nervous system. With the recent discovery of congenital neurological disorders that result from mutations in genes that encode different alpha- and beta-tubulin isotypes (TUBA1A, TUBB2B, TUBA8 and TUBB3), scientists have a novel paradigm to assess how select perturbations in microtubule function affect a range of cellular processes in humans. Moreover, important phenotypic distinctions found among the syndromes suggest that different tubulin isotypes can be utilized for distinct cellular functions during nervous system development.

Evidence of an asymmetrical endophenotype in congenital fibrosis of extraocular muscles type 3 resulting from TUBB3 mutations.

Purpose: Orbital magnetic resonance imaging (MRI) was used to investigate the structural basis of motility abnormalities in congenital fibrosis of the extraocular muscles type 3 (CFEOM3), a disorder resulting from missense mutations in TUBB3, which encodes neuron-specific beta-tubulin isotype III.

Methods: Ophthalmic examinations in 13 volunteers from four CFEOM3 pedigrees and normal control subjects, were correlated with TUBB3 mutation and MRI findings that demonstrated extraocular muscle (EOM) size, location, contractility, and innervation.

Results: Volunteers included clinically affected and clinically unaffected carriers of R262C and D417N TUBB3 amino acid substitutions and one unaffected, mutation-negative family member.

The clinical spectrum of homozygous HOXA1 mutations.

We describe nine previously unreported individuals from six families who have homozygous mutations of HOXA1 and either the Bosley-Salih-Alorainy syndrome (BSAS) or the Athabascan brainstem dysgenesis syndrome (ABDS). Congenital heart disease was present in four BSAS patients, two of whom had neither deafness nor horizontal gaze restriction, thus raising the possibility that cardiovascular malformations might be a clinically isolated, or relatively isolated, manifestation of homozygous HOXA1 mutations. Two ABDS probands had relatively mild mental retardation.