Zhou, h. | bioRxiv Science

bioRxiv2023

Vascular abnormalities in heart and brain are associated with cardiovascular and neurological symptoms in a novel mouse model for Williams syndrome

Williams syndrome is a developmental disorder caused by a microdeletion entailing the loss of a single copy of 25-27 genes on chromosome 7q11.23. Patients suffer from cardiovascular and neuropsychological symptoms. Structural abnormalities of the cardiovascular system in Williams syndrome have been attributed to the hemizygous loss of the elastin (ELN) gene. In contrast, the neuropsychological consequences of Williams syndrome, including sensorimotor deficits, hypersociability and cognitive impairments, have been mainly attributed to altered expression of transcription factors like LIMK1, GTF2I and GTF2IRD1, while the potential impact of altered cerebrovascular function has been largely overlooked. To study the relationship between Williams syndrome mutations and vascularization of both the heart and brain, we generated a mouse model carrying a relatively long microdeletion (LD) that includes the Ncf1 gene, thereby minimizing the confounding impact of hypertension. LD mice had elongated and tortuous aortas but, unlike Eln haploinsufficient mice, showed no signs of structural cardiac hypertrophy. Remarkably, LD mice also displayed structural abnormalities in coronary and brain vessels, including disorganized extracellular matrices. Importantly, LD mice faithfully replicated both cardiovascular and neuropsychological symptoms observed in patients. The phenotype was even more comprehensive than former models, with structure-function correlations evident in aberrant auditory and motor behaviors resembling those in patients with Williams syndrome. Together, our findings suggest that not only cardiovascular but also neuropsychological symptoms in Williams syndrome may be driven in part by vascular abnormalities affecting both heart and brain. Significance StatementWilliams syndrome is caused by microdeletion of 25-27 genes on chromosome 7q11.23, resulting in cardiovascular and neuropsychological symptoms. It remains unclear how the affected genes interact and whether cardiovascular deficits influence brain function. We developed and characterized a mouse model with the longest Williams syndrome microdeletion to date. This model reveals interactions between genes that can be compensatory or additive: haploinsufficiency of Ncf1 may counteract the cardiac hypertrophy caused by Eln deletion, while vascular defects that are potentially due to Eln haploinsufficiency extend to the brain and may worsen neuropsychological symptoms. Our findings support the hypothesis that structural vascular deficits putatively contribute to both cardiac and cognitive phenotypes in Williams syndrome, opening new avenues for understanding and treating this syndrome.

systems biology↗

bioRxiv2021

Knocking-out the human face genes TBX15 and PAX1 in mice alters facial and other physical morphology

DNA variants in or closed to the human TBX15 and PAX1 genes have been repeatedly associated with facial morphology in independent genome-wide association studies, while their functional roles in determining facial morphology remains to be understood. We generated Tbx15 knockout (Tbx15-/-) and Pax1 knockout (Pax1-/-) mice by applying the one-step CRISPR/Cas9 method. A total of 75 adult mice were used for subsequent phenotype analysis, including 38 Tbx15 mice (10 homozygous Tbx15-/-, 18 heterozygous Tbx15+/-, 10 wild-type WT) and 37 Pax1 mice (12 homozygous Pax1-/-, 15 heterozygous Pax1+/-, 10 WT mice). Facial and other physical morphological phenotypes were obtained from three-dimensional (3D) images acquired with the HandySCAN BLACK scanner. Compared to WT mice, the Tbx15-/- mutant mice had significantly shorter faces (P=1.08E-8, R2=0.61) and their ears were in a significantly lower position (P=3.54E-8, R2=0.62) manifesting an "ear dropping" characteristic. Besides these face alternations, Tbx15-/- mutant mice displayed significantly lower weight as well as shorter body and limb length. Pax1-/- mutant mice showed significantly longer noses (P=1.14E-5, R2=0.46) relative to WT mice, but otherwise displayed less obvious morphological alterations than Tbx15-/- mutant mice did. Because the Tbx15 and Pax1 effects on facial morphology we revealed here in mice are largely consistent with previously reported TBX15 and PAX1 face associations in humans, we suggest that the functional role these two genes play on determining the face of mice is similar to the functional impact their human homologues have on the face of humans. Author SummarySeveral independent genome-wide association studies (GWASs) on human facial morphology highlighted DNA variants in or closed to TBX15 and PAX1 with genome-wide significant association with human facial phenotypes. However, direct evidence on the functional involvement if these genes in the development and determination of facial morphology has not been established as of yet. In the current study, our in vivo gene editing experiments in mice for two well-replicated human face TBX15 and PAX1 genes provide novel evidence on the functional involvement of these two genes in facial and other physical morphology in mice, at least. Tbx15-/- mice showed a shortened facial length and manifesting an ear dropping characteristic, Pax1-/- mice showed an increased nose length. Our geometric morphometrics analysis further indicate that there are significant facial morphology differences between groups (Tbx15-/-and Tbx15+/-, Tbx15-/- and Tbx15+/+, Tbx15+/- and Tbx15+/+, Pax1-/- and Pax1+/+). We provide the first direct functional evidence that two well-known and replicated human face genes, Tbx15 and Pax1, impact facial and other body morphology in mice. The general agreement between our findings in knock-out mice with those from previous GWASs suggests that the functional evidence we established here in mice may also be relevant in humans.

genetics↗