Mini-medical school programs decrease perceived barriers of pursuing medical careers among underrepresented minority high school students.

CONTEXT: The percent of underrepresented minority (URM) students who apply to medical school has changed minimally in the past 40 years. Due to the lack of URM applicants, the consequent matriculation of URMs is grossly disproportionate from their percent representation of the US population. Increasing diversity among medical students and physicians has previously been identified as essential to decreasing healthcare disparities among US minorities. OBJECTIVES: The objective of our study was to recognize the barriers of applying to medical school among URMs in high school. METHODS: To identify and assess the prevalence of barriers, surveys were distributed to participants of Med-Achieve, a mini-medical school program of diverse high school students in New York City during the 2019-2020 academic year. RESULTS: Among students who will be first in their immediate family to attend college, 80.0% perceived a barrier to pursuing medical school. Specified barriers indicated include the cost of medical school (77%), a lack of guidance/role models (53.9%), and the predicted inability to do well in medical school classes (53.9%). At the end of the program, a statistically significant reduction in the barrier of lack of guidance/role models was seen. CONCLUSIONS: This study highlights the benefit of mini-medical school programs, especially programs with a mentoring component, to decrease the perceived barriers of applying to medical school among URMs. It also suggests the potential role of similar programs to increase diversity in medicine and to decrease healthcare disparities among minorities in the United States.

Comparison of visceral adipose tissue DNA methylation and gene expression profiles in female adolescents with obesity.

BACKGROUND: Epigenetic changes in visceral adipose tissue (VAT) with obesity and their effects on gene expression are poorly understood, especially during emergent obesity in youth. The current study tested the hypothesis that methylation and gene expression profiles of key growth factor and inflammatory pathways are altered in VAT from obese compared to non-obese youth. METHODS: VAT samples from adolescent females grouped as Lean (L; n = 15; age = 15 ± 3 years, BMI = 21.9 ± 3.0 kg/m2) or Obese (Ob; n = 15, age = 16 ± 2 years, BMI = 45.8 ± 9.8 kg/m2) were collected. Global methylation (n = 20) and gene expression (N = 30) patterns were profiled via microarray and interrogated for differences between groups by ANCOVA (p < 0.05), followed by biological pathway analyses. RESULTS: Overlapping differences in methylation and gene expression in 317 genes were found in VAT from obese compared to lean groups. PI3K/AKT Signaling (p = 1.83 × 10-6; 11/121 molecules in dataset/pathway) was significantly overrepresented in Ob VAT according to pathway analysis. Upregulations in the PI3K/AKT signaling pathway mRNAs TFAM (p = 0.03; fold change = 1.8) and PPP2R5C (p = 0.03, FC = 2.6) were confirmed via qRT-PCR. CONCLUSION: Our analyses show obesity-related differences in DNA methylation and gene expression in visceral adipose tissue of adolescent females. Specifically, we identified methylation site/gene expression pairs differentially regulated and mapped these differences to pathways including PI3K/AKT signaling, suggesting that PI3K/AKT signaling pathway dysfunction in obesity may be driven in part by changes in DNA methylation.

Sexual Dimorphism in Response to an NRF2 Inducer in a Model for Pachyonychia Congenita.

Sex is an influential factor regarding pathophysiology and therapeutic response in human disease. Pachyonychia congenita is caused by mutations in keratin genes and typified by dystrophic lesions affecting nails, glands, oral mucosa, and palmar-plantar epidermis. Painful palmar-plantar keratoderma (PPK) severely impairs mobility in pachyonychia congenita. Mice genetically null for keratin 16 (Krt16), one of the genes mutated in pachyonychia congenita, develop pachyonychia congenita-like PPK. In male Krt16-/- mice, oxidative stress associated with impaired glutathione synthesis and nuclear factor erythroid-derived 2 related factor 2 (NRF2)-dependent gene expression precedes PPK onset, which can be prevented by topical sulforaphane-mediated activation of NRF2. We report here that sulforaphane treatment fails to activate NRF2 and prevent PPK in female Krt16-/- mice despite a similar set of molecular circumstances. Follow-up studies reveal a temporal shift in PPK onset in Krt16-/- females, coinciding with sex-specific fluctuations in footpad skin glutathione levels. Dual treatment with sulforaphane and diarylpropionitrile, an estrogen receptor beta selective agonist, results in NRF2 activation, normalization of glutathione levels, and prevention of PPK in female Krt16-/- mice. These findings point to a sex difference in NRF2 responsiveness that needs be considered when exploring NRF2 as a therapeutic target in skin disorders.

Randomized, split-body, single-blinded clinical trial of topical broccoli sprout extract: Assessing the feasibility of its use in keratin-based disorders.

BACKGROUND: Epidermolysis bullosa simplex is a skin-blistering disorder caused by mutations in keratin (K)14 or K5. Treatment with nuclear factor (erythroid-derived 2)-like 2 inducer sulforaphane ameliorated skin blistering in Krt14-null mice, correlating with induction of K17. To be therapeutically useful for epidermolysis bullosa simplex, topical broccoli sprout extract (BSE), enriched for sulforaphane, would ideally induce the expression of homologous keratins (eg, K6, K17, K16) in the basal layer of human epidermis without impacting expression of defective keratins (K5/K14). OBJECTIVE: The purpose of this 1-week, randomized, split-body, single-blinded, placebo-controlled trial was to assess the impact of BSE on keratin expression. METHODS: Five subjects (34-71 years old) applied BSE (500 nmol of sulforaphane/mL) or vehicle alone to the inner aspect of the arm daily. Expression of keratin, nuclear factor (erythroid-derived 2)-like 2, and other markers was assessed using reverse transcription-polymerase chain reaction and indirect immunofluorescence. RESULTS: One subject (age 71 years) was excluded a posteriori because of poor tissue quality. Topical BSE activated nuclear factor (erythroid-derived 2)-like 2 and up-regulated K17 in the epidermis of all subjects, had variable effects on K16 and K6 expression, and did not alter expression of K14 or K5. LIMITATIONS: Small sample size is a limitation. CONCLUSION: BSE represents an attractive therapeutic candidate for K14-associated epidermolysis bullosa simplex.

Oxidative stress and dysfunctional NRF2 underlie pachyonychia congenita phenotypes.

Palmoplantar keratoderma (PPK) are debilitating lesions that arise in individuals with pachyonychia congenita (PC) and feature upregulation of danger-associated molecular patterns and skin barrier regulators. The defining features of PC-associated PPK are reproduced in mice null for keratin 16 (Krt16), which is commonly mutated in PC patients. Here, we have shown that PPK onset is preceded by oxidative stress in footpad skin of Krt16-/- mice and correlates with an inability of keratinocytes to sustain nuclear factor erythroid-derived 2 related factor 2-dependent (NRF2-dependent) synthesis of the cellular antioxidant glutathione (GSH). Additionally, examination of plantar skin biopsies from individuals with PC confirmed the presence of high levels of hypophosphorylated NRF2 in lesional tissue. In Krt16-/- mice, genetic ablation of Nrf2 worsened spontaneous skin lesions and accelerated PPK development in footpad skin. Hypoactivity of NRF2 in Krt16-/- footpad skin correlated with decreased levels or activity of upstream NRF2 activators, including PKCδ, receptor for activated C kinase 1 (RACK1), and p21. Topical application of the NRF2 activator sulforaphane to the footpad of Krt16-/- mice prevented the development of PPK and normalized redox balance via regeneration of GSH from existing cellular pools. Together, these findings point to oxidative stress and dysfunctional NRF2 as contributors to PPK pathogenesis, identify K16 as a regulator of NRF2 activation, and suggest that pharmacological activation of NRF2 should be further explored for PC treatment.

Thyroid hormone activates protein arginine methyltransferase 1 expression by directly inducing c-Myc transcription during Xenopus intestinal stem cell development.

Adult organ-specific stem cells are essential for organ homeostasis and tissue repair and regeneration. The formation of such stem cells during vertebrate development is poorly understood. Intestinal remodeling during thyroid hormone (T3)-dependent Xenopus metamorphosis resembles postembryonic intestinal maturation in mammals. During metamorphosis, the intestine is remodeled de novo via a yet unknown mechanism. Protein arginine methyltransferase 1 (PRMT1) is up-regulated in and required for adult intestinal stem cells during metamorphosis. PRMT1 up-regulation is the earliest known molecular event for the developing stem cells and is also conserved during zebrafish and mouse intestinal development. To analyze how PRMT1 is specifically up-regulated during the formation of the adult intestinal stem cells, we cloned the Xenopus PRMT1 promoter and characterized it in CaCo-2 cells, a human cell line with intestinal stem cell characteristics. Through a series deletion and mutational analyses, we showed that the stem cell-associated transcription factor c-Myc could bind to a conserved site in the first intron to activate the promoter. Furthermore, we demonstrated that during metamorphosis, both c-Myc and PRMT1 were highly up-regulated, specifically in the remodeling intestine but not the resorbing tail, and that c-Myc was induced by T3 prior to PRMT1 up-regulation. In addition, we showed that T3 directly activated the c-Myc gene during metamorphosis in the intestine via binding of the T3 receptor to the c-Myc promoter. These results suggest that T3 induces c-Myc transcription directly in the intestine, that c-Myc, in turn, activates PRMT1 expression, and that this is an important gene regulation cascade controlling intestinal stem cell development.

Spatio-temporal expression profile of stem cell-associated gene LGR5 in the intestine during thyroid hormone-dependent metamorphosis in Xenopus laevis.

BACKGROUND: The intestinal epithelium undergoes constant self-renewal throughout adult life across vertebrates. This is accomplished through the proliferation and subsequent differentiation of the adult stem cells. This self-renewal system is established in the so-called postembryonic developmental period in mammals when endogenous thyroid hormone (T3) levels are high. METHODOLOGY/PRINCIPAL FINDINGS: The T3-dependent metamorphosis in anurans like Xenopus laevis resembles the mammalian postembryonic development and offers a unique opportunity to study how the adult stem cells are developed. The tadpole intestine is predominantly a monolayer of larval epithelial cells. During metamorphosis, the larval epithelial cells undergo apoptosis and, concurrently, adult epithelial stem/progenitor cells develop de novo, rapidly proliferate, and then differentiate to establish a trough-crest axis of the epithelial fold, resembling the crypt-villus axis in the adult mammalian intestine. The leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) is a well-established stem cell marker in the adult mouse intestinal crypt. Here we have cloned and analyzed the spatiotemporal expression profile of LGR5 gene during frog metamorphosis. We show that the two duplicated LGR5 genes in Xenopus laevis and the LGR5 gene in Xenopus tropicalis are highly homologous to the LGR5 in other vertebrates. The expression of LGR5 is induced in the limb, tail, and intestine by T3 during metamorphosis. More importantly, LGR5 mRNA is localized to the developing adult epithelial stem cells of the intestine. CONCLUSIONS/SIGNIFICANCE: These results suggest that LGR5-expressing cells are the stem/progenitor cells of the adult intestine and that LGR5 plays a role in the development and/or maintenance of the adult intestinal stem cells during postembryonic development in vertebrates.