Neonatal Pial Surface Electroporation

Over the past several years the pial surface has been identified as a germinal niche of importance during embryonic, perinatal and adult neuro- and ...

Cedars-Sinai Medical Center

The Potocki-Lupski syndrome (PTLS) is associated with a microduplication of 17p11.2. Clinical features include multiple congenital and neurobehavioral abnormalities and autistic features. We have generated a PTLS mouse model, Dp(11)17/+, that recapitulates some of the physical and neurobehavioral phenotypes present in patients. Here, we investigated the social behavior and gene expression pattern of this mouse model in a pure C57BL/6-Tyr(c-Brd) genetic background. Dp(11)17/+ male mice displayed normal home-cage behavior but increased anxiety and increased dominant behavior in specific tests. A subtle impairment in the preference for a social target versus an inanimate target and abnormal preference for social novelty (the preference to explore an unfamiliar mouse versus a familiar one) was also observed. Our results indicate that these animals could provide a valuable model to identify the specific gene(s) that confer abnormal social behaviors and that map within this delimited genomic deletion interval. In a first attempt to identify candidate genes and for elucidating the mechanisms of regulation of these important phenotypes, we directly assessed the relative transcription of genes within and around this genomic interval. In this mouse model, we found that candidates genes include not only most of the duplicated genes, but also normal-copy genes that flank the engineered interval; both categories of genes showed altered expression levels in the hippocampus of Dp(11)17/+ mice.

Abnormal social behaviors and altered gene expression rates in a mouse model for Potocki-Lupski syndrome.

Smith-Magenis Syndrome is a contiguous gene syndrome in which the dosage sensitive gene has been identified: the Retinoic Acid Induced 1 (RAI1). Little is known about the function of human RAI1.

Functional and cellular characterization of human Retinoic Acid Induced 1 (RAI1) mutations associated with Smith-Magenis Syndrome.

Mutations in the TRPC6 calcium channel (Transient receptor potential channel 6) gene have been associated with familiar forms of Focal and Segmental Glomerulosclerosis (FSGS) affecting children and adults. In addition, acquired glomerular diseases are associated with increased expression levels of TRPC6. However, the exact role of TRPC6 in the pathogenesis of FSGS remains to be elucidated. In this work we describe the generation and phenotypic characterization of three different transgenic mouse lines with podocyte-specific overexpression of the wild type or any of two mutant forms of Trpc6 (P111Q and E896K) previously related to FSGS. Consistent with the human phenotype a non-nephrotic range of albuminuria was detectable in almost all transgenic lines. The histological analysis demonstrated that the transgenic mice developed a kidney disease similar to human FSGS. Differences of 2-3 folds in the presence of glomerular lesions were found between the non transgenic and transgenic mice expressing Trpc6 in its wild type or mutant forms specifically in podocytes. Electron microscopy of glomerulus from transgenic mice showed extensive podocyte foot process effacement. We conclude that overexpression of Trpc6 (wild type or mutated) in podocytes is sufficient to cause a kidney disease consistent with FSGS. Our results contribute to reinforce the central role of podocytes in the etiology of FSGS. These mice constitute an important new model in which to study future therapies and outcomes of this complex disease.

Podocyte-specific overexpression of wild type or mutant trpc6 in mice is sufficient to cause glomerular disease.

A large fraction of genome variation between individuals is comprised of submicroscopic copy number variation of genomic DNA segments. We assessed the relative contribution of structural changes and gene dosage alterations on phenotypic outcomes with mouse models of Smith-Magenis and Potocki-Lupski syndromes. We phenotyped mice with 1n (Deletion/+), 2n (+/+), 3n (Duplication/+), and balanced 2n compound heterozygous (Deletion/Duplication) copies of the same region. Parallel to the observations made in humans, such variation in gene copy number was sufficient to generate phenotypic consequences: in a number of cases diametrically opposing phenotypes were associated with gain versus loss of gene content. Surprisingly, some neurobehavioral traits were not rescued by restoration of the normal gene copy number. Transcriptome profiling showed that a highly significant propensity of transcriptional changes map to the engineered interval in the five assessed tissues. A statistically significant overrepresentation of the genes mapping to the entire length of the engineered chromosome was also found in the top-ranked differentially expressed genes in the mice containing rearranged chromosomes, regardless of the nature of the rearrangement, an observation robust across different cell lineages of the central nervous system. Our data indicate that a structural change at a given position of the human genome may affect not only locus and adjacent gene expression but also "genome regulation." Furthermore, structural change can cause the same perturbation in particular pathways regardless of gene dosage. Thus, the presence of a genomic structural change, as well as gene dosage imbalance, contributes to the ultimate phenotype.

Phenotypic consequences of copy number variation: insights from Smith-Magenis and Potocki-Lupski syndrome mouse models.

Cimicifuga foetida, an Asian Cimicifuga species, has been employed as a cooling and detoxification agent in traditional Chinese medicine since ancient times. For this herb, two cycloartane triterpene glycosides isolated from the rhizomes have demonstrated cytotoxicity on rat tumor and human cancer cell lines. Since human Hsp27 is increased in various human cancers and exhibits cytoprotective activity that affects tumorigenesis and the susceptibility of tumours to cancer treatment, the purpose of this research was to study the expression of this protein in MCF-7 breast cancer cells. To accomplish this aim, MCF-7 cells were exposed to different concentrations of Cimicifuga foetida extract showing a reduction in cell number measured by the sulforhodamine assay. In addition, the expression of Hsp-27 mRNA detected by RT-PCR and Hsp-27 protein detected by immnofluorescence was present in all conditions, except when using the highest concentration of Cimicifuga foetida extract (2,000 jig /L). We conclude that Hsp 27 expression at 2,000 jig /L Cimicifuga foetida extract is diminished. This is the first report showing the Hsp-27 expression after exposure to Cimicifuga foetida extract in MCF-7 cells.

Effect of the standardized Cimicifuga foetida extract on Hsp 27 expression in the MCF-7 cell line.

Potocki-Lupski syndrome (PTLS) is a genomic disorder associated with an ∼3 Mb duplication in 17p11.2. Clinical features include leanness, intellectual disability, autistic features and developmental deficits. RAI1 gene dosage is associated with the PTLS phenotypes. To understand where and when Rai1 overexpression is detrimental, we generated a mouse that over-expresses Rai1 conditionally in forebrain neurons (I-Rai1). Phenotypic characterization of I-Rai1 mice showed significant underweight, hyperactivity and impaired learning and memory ability compared with wild-type littermates. Doxycycline administration can turn off the transgene expression allowing the restoration of Rai1 normal expression levels. When the transgene was turned off from conception to 3 months of age, no phenotypic differences were observed between I-Rai1 and their wild-type littermates. Surprisingly, we found that turning off the transgene expression before the onset of the phenotypes (1-3 months) or after the onset of the phenotypes (3-5 months) cannot prevent nor reverse the phenotypic outcomes. Our results indicate that Rai1 dosage in forebrain neurons is critical during the development and is related to body weight regulation, activity levels and learning and memory.

Article	Year
Abnormal social behaviors and altered gene expression rates in a mouse model for Potocki-Lupski syndrome. Human molecular genetics\| PubMed ID: 18469339	2008
Functional and cellular characterization of human Retinoic Acid Induced 1 (RAI1) mutations associated with Smith-Magenis Syndrome. BMC molecular biology\| PubMed ID: 20738874	2010
Podocyte-specific overexpression of wild type or mutant trpc6 in mice is sufficient to cause glomerular disease. PloS one\| PubMed ID: 20877463	2010
Phenotypic consequences of copy number variation: insights from Smith-Magenis and Potocki-Lupski syndrome mouse models. PLoS biology\| PubMed ID: 21124890	2010
Effect of the standardized Cimicifuga foetida extract on Hsp 27 expression in the MCF-7 cell line. Biological research\| PubMed ID: 22688911	2011
Correct developmental expression level of Rai1 in forebrain neurons is required for control of body weight, activity levels and learning and memory. Human molecular genetics\| PubMed ID: 24218365	2014

Jessica Molina

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