👤 Skyler Kuhn

The increased prevalence of opioid use disorder (OUD) makes it imperative to disentangle the biological mechanisms contributing to individual differences in OUD vulnerability. OUD shows strong heritability, however genetic variants contributing to vulnerability remain poorly defined. We performed a genome-wide association study using over 850 male and female heterogeneous stock (HS) rats to identify genes underlying behaviors associated with OUD such as nociception, as well as heroin-taking, extinction and seeking behaviors. By using an animal model of OUD, we were able to identify genetic variants associated with distinct OUD behaviors while maintaining a uniform environment, an experimental design not easily achieved in humans. Furthermore, we used a novel non-linear network-based clustering approach to characterize rats based on OUD vulnerability to assess genetic variants associated with OUD susceptibility. Our findings confirm the heritability of several OUD-like behaviors, including OUD susceptibility. Additionally, several genetic variants associated with nociceptive threshold prior to heroin experience, heroin consumption, escalation of intake, and motivation to obtain heroin were identified. Tom1, a microglial component, was implicated for nociception. Several genes involved in dopaminergic signaling, neuroplasticity and substance use disorders, including Brwd1, Pcp4, Phb1l2 and Mmp15 were implicated for the heroin traits. Additionally, an OUD vulnerable phenotype was associated with genetic variants for consumption and break point, suggesting a specific genetic contribution for OUD-like traits contributing to vulnerability. Together, these findings identify novel genetic markers related to the susceptibility to OUD-relevant behaviors in HS rats. Show less

A paradoxical increase of growth hormone (GH) following oral glucose load has been described in ∼30% of patients with acromegaly and has been related to the ectopic expression of the glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) in somatotropinomas. Recently, we identified germline pathogenic variants and somatic loss of heterozygosity of lysine demethylase 1A (KDM1A) in patients with GIP-dependent primary bilateral macronodular adrenal hyperplasia with Cushing's syndrome. The ectopic expression of GIPR in both adrenal and pituitary lesions suggests a common molecular mechanism. We aimed to analyze KDM1A gene sequence and KDM1A and GIPR expressions in somatotroph pituitary adenomas. We conducted a cohort study at university hospitals in France and in Italy. We collected pituitary adenoma specimens from acromegalic patients who had undergone pituitary surgery. We performed targeted exome sequencing (gene panel analysis) and array-comparative genomic hybridization on somatic DNA derived from adenomas and performed droplet digital PCR on adenoma samples to quantify KDM1A and GIPR expressions. One hundred and forty-six patients with sporadic acromegaly were studied; 72.6% presented unsuppressed classical GH response, whereas 27.4% displayed a paradoxical rise in GH after oral glucose load. We did not identify any pathogenic variant in the KDM1A gene in the adenomas of these patients. However, we identified a recurrent 1p deletion encompassing the KDM1A locus in 29 adenomas and observed a higher prevalence of paradoxical GH rise (P = .0166), lower KDM1A expression (4.47 ± 2.49 vs 8.56 ± 5.62, P < .0001), and higher GIPR expression (1.09 ± 0.92 vs 0.43 ± 0.51, P = .0012) in adenomas from patients with KDM1A haploinsufficiency compared with those with 2 KDM1A copies. Unlike in GIP-dependent primary bilateral macronodular adrenal hyperplasia, KDM1A genetic variations are not the cause of GIPR expression in somatotroph pituitary adenomas. Recurrent KDM1A haploinsufficiency, more frequently observed in GIPR-expressing adenomas, could be responsible for decreased KDM1A function resulting in transcriptional derepression on the GIPR locus. Show less

Systemic lupus erythematosus (SLE) increases cardiovascular disease (CVD) risk, and this is not explained by traditional risk factors. Characterization of blood immunologic signatures that associate with subclinical CVD and predict its progression has been challenging and may help identify subgroups at risk. Patients with SLE (n = 77) and healthy controls (HCs) (n = 27) underwent assessments of arterial stiffness, vascular wall inflammation, and coronary atherosclerosis burden with cardio-ankle vascular index (CAVI); fluorodeoxyglucose-positron emission tomography/computed tomography (CT) (target-to-background ratio [TBR]); and coronary CT angiography. Whole blood bulk RNA sequencing was performed in a subset of study participants (HC n = 10, SLE n = 20). In a partially overlapping subset (HC n = 24, SLE n = 64), serum inflammatory protein biomarkers were quantified with an Olink platform. CAVI, TBR, and noncalcified coronary plaque burden (NCB) were increased in patients with SLE compared to HCs. When comparing patients with SLE with high CAVI scores to those with low CAVI scores or to HCs, there was a down-regulation of genes in pathways involved in the cell cycle and differentially regulated pathways related to metabolism. Distinct serum proteins associated with increased CAVI (CCL23, colony-stimulating factor 1, latency-activating peptide transforming growth factor β1, interleukin 33 [IL-33], CD8A, and IL-12B), NCB (monocyte chemotactic protein 4 and FMS-like tyrosine kinase 3 ligand [Flt3L]), and TBR (CD5, IL-1α, AXIN1, cystatin D [CST5], and tumor necrosis factor receptor superfamily 9; P < 0.05). Blood gene expression patterns and serum proteins that associate with worse vascular phenotypes suggest dysregulated immune and metabolic pathways linked to premature CVD. Cytokines and chemokines identified in associations with arterial stiffness, inflammation, and NCB in SLE may allow for characterization of new CVD biomarkers in lupus. Show less

The increased prevalence of opioid use disorder (OUD) makes it imperative to disentangle the biological mechanisms contributing to individual differences in OUD vulnerability. OUD shows strong heritability, however genetic variants contributing toward vulnerability remain poorly defined. We performed a genome-wide association study using over 850 male and female heterogeneous stock (HS) rats to identify genes underlying behaviors associated with OUD such as nociception, as well as heroin-taking, extinction and seeking behaviors. By using an animal model of OUD, we were able to identify genetic variants associated with distinct OUD behaviors while maintaining a uniform environment, an experimental design not easily achieved in humans. Furthermore, we used a novel non-linear network-based clustering approach to characterize rats based on OUD vulnerability to assess genetic variants associated with OUD susceptibility. Our findings confirm the heritability of several OUD-like behaviors, including OUD susceptibility. Additionally, several genetic variants associated with nociceptive threshold prior to heroin experience, heroin consumption, escalation of intake, and motivation to obtain heroin were identified. Tom1, a microglial component, was implicated for nociception. Several genes involved in dopaminergic signaling, neuroplasticity and substance use disorders, including Brwd1, Pcp4, Phb1l2 and Mmp15 were implicated for the heroin traits. Additionally, an OUD vulnerable phenotype was associated with genetic variants for consumption and break point, suggesting a specific genetic contribution for OUD-like traits contributing to vulnerability. Together, these findings identify novel genetic markers related to the susceptibility to OUD-relevant behaviors in HS rats. Show less

Mutations in the lysosomal membrane protein CLN3 cause Juvenile Neuronal Ceroid Lipofuscinosis (JNCL). Activation of the lysosomal ion channel TRPML1 has previously been shown to be beneficial in several neurodegenerative disease models. Here, we tested whether TRPML1 activation rescues disease-associated phenotypes in CLN3-deficient retinal pigment epithelial (ARPE-19 CLN3-KO) cells. ARPE-19 CLN3-KO cells accumulate LAMP1 positive organelles and show lysosomal storage of mitochondrial ATPase subunit C (SubC), globotriaosylceramide (Gb3), and glycerophosphodiesters (GPDs), whereas lysosomal bis(monoacylglycero)phosphate (BMP/LBPA) lipid levels were significantly decreased. Activation of TRPML1 reduced lysosomal storage of Gb3 and SubC but failed to restore BMP levels in CLN3-KO cells. TRPML1-mediated decrease of storage was TFEB-independent, and we identified TRPML1-mediated enhanced lysosomal exocytosis as a likely mechanism for clearing storage including GPDs. Therefore, ARPE-19 CLN3-KO cells represent a human cell model for CLN3 disease showing many of the described core lysosomal deficits, some of which can be improved using TRPML1 agonists. Show less

Dietary fat absorption by the small intestine is a multistep process that regulates the uptake and delivery of essential nutrients and energy. One step of this process is the temporary storage of dietary fat in cytoplasmic lipid droplets (CLDs). The storage and mobilization of dietary fat is thought to be regulated by proteins that associate with the CLD; however, mechanistic details of this process are currently unknown. In this study we analyzed the proteome of CLDs isolated from enterocytes harvested from the small intestine of mice following a dietary fat challenge. In this analysis we identified 181 proteins associated with the CLD fraction, of which 37 are associated with known lipid related metabolic pathways. We confirmed the localization of several of these proteins on or around the CLD through confocal and electron microscopy, including perilipin 3, apolipoprotein A-IV, and acyl-CoA synthetase long-chain family member 5. The identification of the enterocyte CLD proteome provides new insight into potential regulators of CLD metabolism and the process of dietary fat absorption. Show less

This review focuses on a number of new data on biology and pathophysiology of the metabolic syndrome (MetS) and the involvement of nuclear receptors that have been presented during the last Endocrine Society meeting, held in Houston in June 2012. Several studies have reported beneficial effects of various orphan nuclear receptors, including SHP (Small Heterodimeric Partner, NR0B2) and LXR (Liver X Receptor, NR1H3 and NR1H2), on various components of MetS. By using an inactivation model of SHP, David Moore has shown that SHP exerts "antidiabetic" effects but associated with hepatic steatosis development. He also showed that DLPC (dilauroyl phosphatidylcholine), an unconventional phospholipid, exhibited anti-diabetic properties through its binding to LRH-1 (Liver Receptor Homolog-1, NR5A2), a molecular partner of SHP. Interestingly, Carolyn Cummins investigated LXR α and β isoforms knock-out mice and provided experimental evidence for the detailed mechanisms involved in the deleterious metabolic effects of glucocorticoids, pointing out to the functional interaction between LXRβ, and the glucocorticoid receptor. These new and original studies open new therapeutic opportunities for the management of metabolic disorders in humans by selective modulators of these receptors. Show less

A genetic locus controlling the electrophoretic mobility of an acid phosphatase in the rat (Rattus norvegicus) is described. The locus, designed Acp-2, is not expressed in erythrocytes but is expressed in all other tissues studied. The product of Acp-2 hydrolyzes a wide variety of phosphate monoesters and is inhibited by L(+)-tartaric acid. Inbred rat strains have fixed either allele Acp-2a or allele Acp-2b. Codominant expression is observed in the respective F1 hybrids. Backcross progenies revealed the expected 1:1 segregation ratio. Possible loose linkage was found between the Acp-2 and the Pep-3 gene loci at a recombination frequency of 0.36 +/- 0.06. Show less