Biology subjects

Pavan, W. J.

Publications and source records attributed to Pavan, W. J..

5 recordsLinked to original sources

bioRxiv2025

Systemic neonatal AAV9 gene therapy delivery improves behavioral and phenotypic outcomes comparable to intracerebroventricular delivery in a mouse model of Niemann-Pick disease, type C1

Niemann-Pick disease, type C (NPC), is an inherited fatal lysosomal storage disorder caused by a mutation in the NPC1 or NPC2 genes and characterized by impaired lysosomal cholesterol export. Previous studies have demonstrated that delivery of the NPC1 gene to the central nervous system (CNS) via an adeno-associated virus (AAV) can substantially improve lifespan and mitigate signs of disease in Npc1-deficient mouse models of NPC. To determine the optimal parameters for an efficacious AAV-based gene therapy for NPC, we measured the survival and disease phenotypes of mice treated systemically as neonates or at weaning age, along with neonatal mice treated via intracerebroventricular (ICV) delivery, with a construct containing either a ubiquitous truncated EF1 promoter or a truncated Mecp2 promoter. While all constructs and delivery methods resulted in improvement compared with baseline, mice treated as neonates survived significantly longer and experienced slower disease progression compared with those treated systemically at weaning age. Systemic delivery to neonates was capable of increasing survival and phenotypic improvement comparable to that of ICV delivery, and neonatal systemic and ICV delivery were both similarly capable of near-total Purkinje cell rescue. We also found no difference between a ubiquitous EF1-derived promoter and an Mecp2-derived promoter. Ultimately, early treatment with maximal access to the CNS, whether via systemic or direct CNS delivery, is key to the efficacy of gene therapy in treating NPC.

neuroscience↗

bioRxiv2024

Optimization of systemic AAV9 gene therapy in Niemann-Pick disease type C1 mice

Niemann-Pick disease, type C1 (NPC1) is a rare, fatal neurodegenerative disorder caused by pathological variants in NPC1, which encodes a lysosomal cholesterol transporter. FDA-approved treatments are limited and do not target the underlying genetic defect. Both systemic and central nervous system (CNS) delivery of AAV9-hNPC1 have shown significant disease amelioration in NPC1 murine models. To assess the impact of dose in null Npc1m1N/m1N mice, we systemically administered three different doses of AAV9-hNPC1 at 4 weeks old. Then, to assess the impact of age, we administered the medium dose before phenotypic onset or at early- or late-stage of disease progression (4, 6 or 8 weeks old, respectively). Higher vector doses and earlier treatment were associated with significantly increased lifespan, slower disease progression, and enhanced CNS transduction. In Npc1I1061T/I1061T mice, a model recapitulating a common human hypomorphic variant, similar benefits ensued. Our findings help define dose ranges, treatment ages, and efficacy in hypomorphic models of NPC1 deficiency and suggest that higher doses of AAV9-hNPC1 in pre-symptomatic disease states are likely to yield better outcomes in NPC1 individuals. Summary BlurbSystemic AAV9-hNPC1 gene therapy in null Npc1m1N mice at higher doses or with earlier administration and treatment of hypomorphic Npc1I1061T mice delays disease progression and increases lifespan.

neuroscience↗

bioRxiv2022

The relationship between PD-L1 and quiescence in melanocyte stem cell aging.

A central aspect of life-long stem cell function in slow cycling stem cells is the proper regulation of cellular quiescence. How the quiescent state is achieved, whether all quiescent cells are equivalent, and if the quiescent stem cell pool changes with age are all questions that remain unanswered. Using quiescent melanocyte stem cells (qMcSC) as a model, we found that stem cell quiescence is neither a singular nor static process and can be heterogeneous. As one example of this heterogeneity, we show that a portion of qMcSCs expresses the immune checkpoint protein PD-L1 at the cell membrane (PD-L1mem+), PD-L1mem+ qMcSCs are better retained with age, and that the aged quiescent McSC pool is transcriptomically more deeply quiescent. Collectively these findings demonstrate that PD-L1 expression is a physiological attribute of quiescence in McSCs and PD-L1mem+ quiescent stem cells may be good targets for reactivation in the context of aging.

cell biology↗

bioRxiv2022

Expanded Analysis of Pigmentation Genetics in UK Biobank

The genetics of pigmentation is an excellent model for understanding gene interactions in a trait almost entirely unaffected by environment. We have analysed pigmentation phenotypes in UK Biobank using DISSECT, a tool which enables genome-wide association studies (GWAS) whilst accounting for relatedness between individuals, and thus allows a much larger cohort to be studied. We have increased the number of candidate genes associated with red and blonde hair colour, basal skin colour and tanning response to UV radiation. As previously described, we find almost all red hair individuals have two variant MC1R alleles; exome sequence data expands the number of associated coding variants. Rare red-headed individuals with only a single MC1R variant are enriched for an associated eQTL at the ASIP gene. We find that females are most likely to self-report red or blonde hair, paler skin and less tanning ability than men, and that variants at KITLG, MC1R, OCA2 and IRF4 show significant sex differences in effect. After taking sex into account, pigmentation phenotypes are not correlated with sex hormone levels, except for tanning ability, which shows a positive correlation with testosterone in men. Across the UK there is a correlation between place of birth and hair colour; red hair being more common in the north and west, whilst blonde hair is more common in the east. Combining GWAS with transcriptome data to generate a transcriptome wide association study identifies candidate genes whose expression in skin or melanocytes shows association with pigmentation phenotypes. A comparison of candidates associated with different pigmentation phenotypes finds that candidates for blonde hair, but not skin colour, are enriched for skin and hair genes suggesting that it may be hair shape and structure that impacts hair colour, rather than the melanocyte/keratinocyte interaction.

genetics↗

bioRxiv2017

Cell-type specific eQTL of primary melanocytes facilitates identification of melanoma susceptibility genes

Most expression quantitative trait loci (eQTL) studies to date have been performed in heterogeneous tissues as opposed to specific cell types. To better understand the cell-type specific regulatory landscape of human melanocytes, which give rise to melanoma but account for <5% of typical human skin biopsies, we performed an eQTL analysis in primary melanocyte cultures from 106 newborn males. We identified 597,335 cis-eQTL SNPs prior to LD-pruning and 4,997 eGenes (FDR<0.05), which are higher numbers than in any GTEx tissue type with a similar sample size. Melanocyte eQTLs differed considerably from those identified in the 44 GTEx tissues, including skin. Over a third of melanocyte eGenes, including key genes in melanin synthesis pathways, were not observed to be eGenes in two types of GTEx skin tissues or TCGA melanoma samples. The melanocyte dataset also identified cell-type specific trans-eQTLs with a pigmentation-associated SNP for four genes, likely through its cis-regulation of IRF4, encoding a transcription factor implicated in human pigmentation phenotypes. Melanocyte eQTLs are enriched in cis-regulatory signatures found in melanocytes as well as melanoma-associated variants identified through genome-wide association studies (GWAS). Co-localization of melanoma GWAS variants and eQTLs from melanocyte and skin eQTL datasets identified candidate melanoma susceptibility genes for six known GWAS loci including unique genes identified by the melanocyte dataset. Further, a transcriptome-wide association study using published melanoma GWAS data uncovered four new loci, where imputed expression levels of five genes (ZFP90, HEBP1, MSC, CBWD1, and RP11-383H13.1) were associated with melanoma at genome-wide significant P-values. Our data highlight the utility of lineage-specific eQTL resources for annotating GWAS findings and present a robust database for genomic research of melanoma risk and melanocyte biology.

genetics↗