A kinase-dead Csf1r mutation associated with adult-onset leukoencephalopathy has a dominant inhibitory impact on CSF1R signalling

in Development (2022), 149(8),

Amino acid substitutions in the kinase domain of the human CSF1R gene are associated with autosomal dominant adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). To model the ... [more ▼]

Amino acid substitutions in the kinase domain of the human CSF1R gene are associated with autosomal dominant adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). To model the human disease, we created a disease-associated mutation (pGlu631Lys; E631K) in the mouse Csf1r locus. Homozygous mutation (Csf1rE631K/E631K) phenocopied the Csf1r knockout, with prenatal mortality or severe postnatal growth retardation and hydrocephalus. Heterozygous mutation delayed the postnatal expansion of tissue macrophage populations in most organs. Bone marrow cells from Csf1rE631K/+mice were resistant to CSF1 stimulation in vitro, and Csf1rE631K/+ mice were unresponsive to administration of a CSF1-Fc fusion protein, which expanded tissue macrophage populations in controls. In the brain, microglial cell numbers and dendritic arborisation were reduced in Csf1rE631K/+ mice, as in patients with ALSP. The microglial phenotype is the opposite of microgliosis observed in Csf1r+/- mice. However, we found no evidence of brain pathology or impacts on motor function in aged Csf1rE631K/+ mice. We conclude that heterozygous disease-associated CSF1R mutations compromise CSF1R signalling. We speculate that leukoencephalopathy associated with dominant human CSF1R mutations requires an environmental trigger and/or epistatic interaction with common neurodegenerative disease-associated alleles. [less ▲]

Transcriptome of human foetal heart compared with cardiomyocytes from pluripotent stem cells

in Development (2015)

Pax1 and Pax9 activate Bapx1 to induce chondrogenic differentiation in the sclerotome.

in Development (2003), 130(3), 473-82

We have previously shown that the paired-box transcription factors Pax1 and Pax9 synergistically act in the proper formation of the vertebral column. Nevertheless, downstream events of the Pax1/Pax9 ... [more ▼]

We have previously shown that the paired-box transcription factors Pax1 and Pax9 synergistically act in the proper formation of the vertebral column. Nevertheless, downstream events of the Pax1/Pax9 action and their target genes remain to be elucidated. We show, by analyzing Pax1;Pax9 double mutant mice, that expression of Bapx1 in the sclerotome requires the presence of Pax1 and Pax9, in a gene dose-dependent manner. By using a retroviral system to overexpress Pax1 in chick presomitic mesoderm explants, we show that Pax1 can substitute for Shh in inducing Bapx1 expression and in initiating chondrogenic differentiation. Furthermore, we demonstrate that Pax1 and Pax9 can transactivate regulatory sequences in the Bapx1 promoter and that they physically interact with the Bapx1 promoter region. These results strongly suggest that Bapx1 is a direct target of Pax1 and Pax9. Together, we conclude that Pax1 and Pax9 are required and sufficient for the chondrogenic differentiation of sclerotomal cells. [less ▲]

Pax1 is expressed during development of the thymus epithelium and is required for normal T-cell maturation.

in Development (1996), 122(1), 23-30

Pax1 is a transcriptional regulatory protein expressed during mouse embryogenesis and has been shown to have an important function in vertebral column development. Expression of Pax1 mRNA in the embryonic ... [more ▼]

Pax1 is a transcriptional regulatory protein expressed during mouse embryogenesis and has been shown to have an important function in vertebral column development. Expression of Pax1 mRNA in the embryonic thymus has been reported previously. Here we show that Pax1 protein expression in thymic epithelial cells can be detected throughout thymic development and in the adult. Expression starts in the early endodermal epithelium lining the foregut region and includes the epithelium of the third pharyngeal pouch, a structure giving rise to part of the thymus epithelium. In early stages of thymus development a large proportion of thymus cells expresses Pax1. With increasing age, the proportion of Pax1-expressing cells is reduced and in the adult mouse only a small fraction of cortical thymic stromal cells retains strong Pax1 expression. Expression of Pax1 in thymus epithelium is necessary for establishing the thymus microenvironment required for normal T cell maturation. Mutations in the Pax-1 gene in undulated mice affect not only the total size of the thymus but also the maturation of thymocytes. The number of thymocytes is reduced about 2- to 5-fold, affecting mainly the CD4+8+ immature and CD4+ mature thymocyte subsets. The expression levels of major thymocyte surface markers remains unchanged with the exception of Thy-1 which was found to be expressed at 3- to 4-fold higher levels. [less ▲]

Expression and function of Pax 1 during development of the pectoral girdle.

in Development (1994), 120(10), 2773-85

Pax 1 is a member of the paired-box containing gene family. Expression has previously been observed in the developing sclerotomes and later in the anlagen of the intervertebral discs. Analysis of Pax 1 ... [more ▼]

Pax 1 is a member of the paired-box containing gene family. Expression has previously been observed in the developing sclerotomes and later in the anlagen of the intervertebral discs. Analysis of Pax 1-deficient undulated mice revealed an important role for this gene in the development of the axial skeleton, in which Pax 1 apparently functions as a mediator of notochordal signals during sclerotome differentiation. Here we demonstrate that Pax 1 is also transiently expressed in the developing limb buds. A comparative phenotypic analysis of different undulated alleles shows that this expression is of functional significance. In mice that are mutant for the Pax 1 gene severe developmental abnormalities are found in the pectoral girdle. These include fusions of skeletal elements which would normally remain separate, and failures in the differentiation of blastemas into cartilaginous structures. Although Pax 1 is also expressed in the developing hindlimb buds and Wolffian ridge, no malformations could be detected in the corresponding regions of Pax 1 mutant mice. These findings show that, in addition to its role in the developing vertebral column, Pax 1 has an important function in the development of parts of the appendicular skeleton. [less ▲]

The role of Pax-1 in axial skeleton development.

in Development (1994), 120(5), 1109-21

Previous studies have identified a single amino-acid substitution in the transcriptional regulator Pax-1 as the cause of the mouse skeletal mutant undulated (un). To evaluate the role of Pax-1 in the ... [more ▼]

Previous studies have identified a single amino-acid substitution in the transcriptional regulator Pax-1 as the cause of the mouse skeletal mutant undulated (un). To evaluate the role of Pax-1 in the formation of the axial skeleton we have studied Pax-1 protein expression in early sclerotome cells and during subsequent embryonic development, and we have characterized the phenotype of three different Pax-1 mouse mutants, un, undulated-extensive (unex) and Undulated short-tail (Uns). In the Uns mutation the whole Pax-1 locus is deleted, resulting in the complete absence of Pax-1 protein in these mice. The other two genotypes are interpreted as hypomorphs. We conclude that Pax-1 is necessary for normal vertebral column formation along the entire axis, although the severity of the phenotype is strongest in the lumbar region and the tail. Pax-1-deficient mice lack vertebral bodies and intervertebral discs. The proximal part of the ribs and the rib homologues are also missing or severely malformed, whereas neural arches are nearly normal. Pax-1 is thus required for the development of the ventral parts of vertebrae. Embryonic analyses reveal that although sclerotomes are formed in mutant embryos, abnormalities can be detected from day 10.5 p.c. onwards. The phenotypic analyses also suggest that the notochord still influences vertebral body formation some days after the sclerotomes are formed. Furthermore, the notochord diameter is larger in mutant embryos from day 12 p.c., due to increased cell proliferation. In the strongly affected genotypes the notochord persists as a rod-like structure and the nucleus pulposus is never properly formed. Since the notochord is Pax-1-negative these findings suggest a bidirectional interaction between notochord and paraxial mesoderm. The availability of these Pax-1 mutant alleles permitted us to define an early role for Pax-1 in sclerotome patterning as well as a late role in intervertebral disc development. Our observations suggest that Pax-1 function is required for essential steps in ventral sclerotome differentiation, i.e. for the transition from the mesenchymal stage to the onset of chondrogenesis. [less ▲]

Separate elements cause lineage restriction and specify boundaries of Hox-1.1 expression.

in Development (1991), 112(1), 279-87

The Hox genes are a class of putative developmental control genes that are thought to be involved in the specification of positional identity along the anteroposterior axis of the vertebrate embryo. It is ... [more ▼]

The Hox genes are a class of putative developmental control genes that are thought to be involved in the specification of positional identity along the anteroposterior axis of the vertebrate embryo. It is apparent from their expression pattern that their regulation is dependent upon positional information. In a previous analysis of the Hox-1.1 promoter in transgenic mice, we identified sequences that were sufficient to establish transgene expression in a specific region of the embryo. The construct used, however, did not contain enough regulatory sequences to reproduce all aspects of Hox-1.1 expression. In particular, neither a posterior boundary nor a restriction of expression to prevertebrae was achieved. Here we show correct regulation by Hox-1.1 sequences in transgenic mice and identify the elements responsible for different levels of control. Concomitant with the subdivision of mesodermal cells into different lineages during gastrulation and organogenesis, Hox-1.1 expression is restricted to successively smaller sets of cells. Distinct elements are required at different stages of development to execute this developmental programme. One position-responsive element (130 bp nontranslated leader) was shown to be crucial for the restriction of expression not only along the anteroposterior axis of the embryo, setting the posterior border, but also along the dorsoventral axis of the neural tube and to the lineage giving rise to the prevertebrae. Thus, Hox-1.1 expression is established in a specific region of the embryo and in a specific lineage of the mesoderm by restricting the activity of the promoter by the combined effect of several regulatory elements. [less ▲]

Position-specific activity of the Hox1.1 promoter in transgenic mice.

in Development (1990), 108(3), 435-42

During development, positional values have to be assigned to groups of cells. The murine Hox genes are a class of genes that are predicted to be involved at some stage in this process. During ... [more ▼]

During development, positional values have to be assigned to groups of cells. The murine Hox genes are a class of genes that are predicted to be involved at some stage in this process. During embryogenesis they are expressed in distinct overlapping region- and stage-specific patterns and therefore must be regulated in response to positional information. In this study, we have analysed the activity of Hox1.1 promoter sequences in transgenic mice. The use of lacZ as a marker allows a detailed analysis of expression at the single cell level during early embryonic development. We show that 3.6 kbp of promoter and 1.7 kbp of 3' sequences provide sufficient regulatory information to express a transgene in a spatial and temporal manner indistinguishable from the endogenous Hox1.1 gene during the period of development when Hox1.1 expression is established. The activation occurs in a strict order in specific ectodermal and mesodermal domains. Within each of these domains the transgene is activated over a period of four hours apparently randomly in single cells. In a following second period, Hox1.1 and transgene expression patterns diverge. In this period, transgene expression persists in many mesodermally derived cells that do not express Hox1.1 indicating the absence of a negative regulatory element in the transgene. The anterior boundary of transgene expression is identical to that of Hox1.1. However, no posterior boundary of transgene expression is set, suggesting that a separate element absent from the transgene specifies this boundary. [less ▲]