Biology subjects

Loftus, S. K.

Publications and source records attributed to Loftus, S. K..

5 recordsLinked to original sources

bioRxiv2026

Targeting melanosome pH is an effective method for the treatment of oculocutaneous albinism

Oculocutaneous albinism (OCA) is a genetic condition associated with impaired visual acuity and increased skin cancer risk. When OCA is due to defects in melanosome ion transport, abnormally acidic conditions in the melanosome lumen inhibit tyrosinase, the critical pigment synthetic enzyme. Hence, a therapeutic approach that optimizes melanosome pH to increase pigment production presents a potential treatment for OCA and a method for decreasing skin cancer risk. Here, we report that reduction in sAC (ADCY10) activity via naturally occurring human variants in ADCY10 restores OCA pigmentation, and sAC inhibition increases melanin synthesis in both human and mouse OCA models. These findings demonstrate that targeting melanosome pH is an effective, previously untapped therapeutic strategy for OCA and elevated skin cancer risk.

physiology↗

bioRxiv2025

Ampyrone (4-Aminoantipyrine) is a Direct Agonist of Human Tyrosinase and Potential Therapeutic for Oculocutaneous Albinism and Disorders of Hypopigmentation.

Significant loss of pigmentation can increase visual disability, skin cancer risk, and psychosocial stress. Tyrosinase (TYR) catalyzes the first and rate-limiting step of melanin synthesis. Inhibitors of TYR are well established and are currently used in clinical settings; however, there is a dearth of direct activators of TYR. Here, using a unique human TYR construct, high-throughput screening, and computational analysis techniques, we identified ampyrone as a TYR activator. Ampyrone increased the in vitro catalytic activity of the intramelanosomal domain of human TYR (hTYR) and its hypomorphic variant, P406L, a cause of oculocutaneous albinism type 1B (OCA1B). Moreover, ampyrone induced melanin synthesis in both wild-type and OCA1B human melanocytes, as well as 3-dimension (3D) human skin cultures. Our results reveal ampyrone as a lead compound for first-in-class TYR activators, potentially accelerating the discovery of novel therapies for patients with genetic and acquired diseases of hypopigmentation.

pharmacology and toxicology↗

bioRxiv2025

Neuronal titration of Snca via enhancer disruption mitigates disease onset in a Parkinson's disease mouse model

-synuclein (SNCA) is the greatest genetic risk factor for sporadic Parkinsons Disease (PD). Misfolding and overexpression of SNCA underlie pathognomonic features of PD, including SNCA aggregates and midbrain dopaminergic (mbDA) neurodegeneration. We recently identified an SNCA intronic sequence that harbors variation associated with PD risk and demonstrated its role as a neuronal cis-regulatory element (CRE). Here, we engineered a mouse model lacking this sequence, which exhibits significantly reduced Snca transcription in mbDA neurons. Employing a battery of motor, molecular, and histological assays in an established mouse model of PD, we demonstrate that mice lacking this Snca enhancer are protected against PD-relevant histopathology and motor impairments. By targeting a cell-dependent CRE to diminish PD onset/progression in mice, we introduce a potentially powerful therapeutic avenue for PD.

genetics↗

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↗