During mouse development, the ventral spinal cord becomes organized into five progenitor domains that express different combinations of transcription factors and generate different subsets of neurons and glia. One of these domains, known as the p2 domain, generates two subtypes of interneurons, V2a and V2b. Here we have used genetic fate mapping and loss-of-function analysis to show that the transcription factor Sox1 is expressed in, and is required for, a third type of p2-derived interneuron, which we named V2c. These are close relatives of V2b interneurons, and, in the absence of Sox1, they switch to the V2b fate. In addition, we show that late-born V2a and V2b interneurons are heterogeneous, and subsets of these cells express the transcription factor Pax6. Our data demonstrate that interneuron diversification in the p2 domain is more complex than previously thought and directly implicate Sox1 in this process.

Neural stem/progenitor cells maintain their identity via continuous self-renewal and suppression of differentiation. Gain-of-function experiments in the chick revealed an involvement for Sox1-3 transcription factors in the maintenance of the undifferentiated neural progenitor (NP) identity. However, the mechanism(s) employed by each factor has not been resolved. Here, we derived cortical neural/ stem progenitor cells from wild-type and Sox1-null mouse embryos and found that Sox1 plays a key role in the suppression of neurogenic cell divisions. Loss of Sox1 leads to progressive depletion of self-renewing cells, elongation of the cell cycle of proliferating cells, and significant increase in the number of cells exiting the cell cycle. In proliferating NP cells, Sox1 acts via a prospero-related homeobox 1 (Prox1)-mediated pathway to block cell cycle exit that leads to neuronal differentiation in vivo and in vitro. Thus, our results demonstrate that Sox1 regulates the size of the cortical NP pool via suppression of Prox1-mediated neurogenic cell divisions. STEM CELLS 2011;29:89-98 Disclosure of potential conflicts of interest is found at the end of this article.

Spinal cord injury (SCI) is a major health burden and currently there is no effective medical intervention. Research performed over the last decade revealed that cells surrounding the central canal of the adult spinal cord and forming the ependymal layer acquire stem cell properties either in vitro or in response to injury. Following SCI activated ependymal cells generate progeny cells which migrate to the injury site but fail to produce the appropriate type of cells in sufficient number to limit the damage, rendering this physiological response mainly ineffective. Research is now focusing on the manipulation of ependymal cells to produce cells of the oligodendrocyte lineage which are primarily lost in such a situation leading to secondary neuronal degeneration. Thus, there is a need for a more focused approach to understand the molecular properties of adult ependymal cells in greater detail and develop effective strategies for guiding their response during SCI.

Spinal ventral interneurons regulate the activity of motor neurons, thereby controlling motor activities. Interneurons arise during embryonic development from distinct progenitor domains distributed orderly along the dorso-ventral axis of the neural tube. A single ventral progenitor population named p2 generates at least five V2 interneuron subsets. Whether the diversification of V2 precursors into multiple subsets occurs within the p2 progenitor domain or involves a later compartment of early-born V2 interneurons remains unsolved. Here, we provide evidence that the p2 domain produces an intermediate V2 precursor compartment characterized by the transient expression of the transcriptional repressor Vsx1. These cells display an original repertoire of cellular markers distinct from that of any V2 interneuron population. They have exited the cell cycle but have not initiated neuronal differentiation. They coexpress Vsx1 and Foxn4, suggesting that they can generate the known V2 interneuron populations as well as possible additional V2 subsets. Unlike V2 interneurons, the generation of Vsx1-positive precursors does not depend on the Notch signaling pathway but expression of Vsx1 in these cells requires Pax6. Hence, the p2 progenitor domain generates an intermediate V2 precursor compartment, characterized by the presence of the transcriptional repressor Vsx1, that contributes to V2 interneuron development.

No abstract

ATTRV30M amyloid neuropathy is a lethal autosomal dominant sensorimotor and autonomic neuropathy, caused by deposition of amyloid fibrils composed of aberrant transthyretin (TTR). Ages of onset and penetrance exhibit great variability and genetic factors have been implicated. Complement activation co-localizes with amyloid deposits in amyloidotic neuropathy and is possibly involved in the kinetics of amyloidogenesis. A candidate gene approach has recently identified C1q polymorphisms to correlate with disease onset in a Cypriot cohort of patients with ATTRV30M amyloid neuropathy. In the current study we use a double transgenic mouse model of ATTRV30M amyloid neuropathy in which C1q is ablated to elucidate further a possible modifier role for C1q. Amyloid deposition is found to be increased by 60% in the absence of C1q. Significant up regulation is also recorded in apoptotic and cellular stress markers reflecting extracellular toxicity of pre-fibrillar and fibrillar TTR. Our data further indicate that in the absence of C1q there is marked reduction of macrophages in association with amyloid deposits and thus less effective phagocytosis of TTR.

According to the amyloid hypothesis of Alzheimer’s disease (AD) the deposition of prefibrillar and fibrillar Aβ peptide sets off the pathogenic cascades of neuroinflammation and neurodegeneration that lead to synaptic and neuronal loss resulting in cognitive decline. Various approaches to reduce amyloid load by reducing production of the Aβ peptide or enhancing amyloid clearance by primary or secondary immunization have not proven successful in clinical trials. Interfering with the normal function of secretases and suboptimal timing of Aβ peptide removal have been put forward as possible explanations. Complement, an innate component of the immune system, has been found to modulate disease pathology and in particular neuronal loss in the AD mouse model but its mechanism of action is complex. C1Q has been shown to facilitate phagocytosis of Aβ peptide but its Ablation attenuates neuroinflammation. Experiments in AD mouse models show that inhibition of complement component C5a reduces amyloid deposition and alleviates neuroinflammation. Phagocytes including microglia, monocytes and neutrophils carry C5a receptors. Here, a widely used mouse model of AD, 5XFAD, was intermittently treated with the oral C5a receptor agonist EP67 and several neuronal and neuroinflammatory markers as well as memory function were assessed. EP67 treatment enhanced phagocytosis, resulting in a significant reduction of both fibrillar and non-fibrillar Aβ, reduced astrocytosis and preserved synaptic and neuronal markers as well as memory function. Timely and phasic recruitment of the innate immune system offers a new therapeutic avenue of treating pre-symptomatic Alzheimer disease.

Background: ATTRV30M amyloidosis is a lethal autosomal dominant sensorimotor and autonomic neuropathy caused by amyloid deposition composed of aggregated misfolded TTR monomers with the V30M mutation. The age of onset in patients with ATTRV30M varies in different foci and the mechanism behind it is still unknown. Methods:The tertiary neurology center following all ATTRV30M patients in Cyprus was used to collect demographic data to estimate; prevalence, incidence, penetrance, anticipation, time from disease onset to diagnosis and transplantation. Ocular, cardiac and leptomeningeal involvement in transplanted patients was explored. Correlation of C1q tagging SNPs with age of disease onset was carried out.Results: Prevalence and incidence for ATTRV30M neuropathy in Cyprus are 5.4/100,000 and 0.3/100,000 respectively. Mean age of onset is 40.6 years and anticipation is 8.3 years.Penetrance reaches 51% and 75% by the ages of 50 and 80 years respectively. In liver transplanted patients rates of ocular, cardiac and leptomeningeal involvement were estimated to be 60%, 20% and 16% respectively. C1q polymorphisms correlated with age of disease onset.Conclusion: ATTRV30M neuropathy has a rising prevalence in Cyprus due to improved survival of patients. Late onset complications are becoming a major problem. Complement C1q appears to be a modifier in this disease.