Microplastics are created for commercial use, are shed from textiles, or result from the breakdown of larger plastic items. Recent reports have shown that microplastics accumulate in human tissues and may have adverse health consequences. Currently, there are no standardized environmental monitoring systems to track microplastic accumulation within human tissues. Using Raman spectroscopy, we investigated the temporal exposures to plastic pollution in Hawai'i and noted a significant increase in the accumulation of microplastics in discarded placentas over the past 15 years, with changes in the size and chemical composition of the polymers. These findings provide a rare insight into the vulnerability and sensitivity of Pacific Island residents to plastic pollution and illustrate how discarded human tissues can be used as an innovative environmental plastic pollution monitoring system.

Selenoprotein K (SELENOK) is a selenocysteine (Sec)-containing protein localized in the endoplasmic reticulum (ER) membrane where it interacts with the DHHC6 (where single letter symbols represent Asp-His-His-Cys amino acids) enzyme to promote protein acyl transferase (PAT) reactions. PAT reactions involve the DHHC enzymatic capture of palmitate via a thioester bond to cysteine (Cys) residues that form an unstable palmitoyl-DHHC intermediate, followed by transfer of palmitate to Cys residues of target proteins. How SELENOK facilitates this reaction has not been determined. Splenocyte microsomal preparations from wild-type mice versus SELENOK knockout mice were used to establish PAT assays and showed decreased PAT activity (~50%) under conditions of SELENOK deficiency. Using recombinant, soluble versions of DHHC6 along with SELENOK containing Sec₉₂, Cys₉₂, or alanine (Ala₉₂), we evaluated the stability of the acyl-DHHC6 intermediate and its capacity to transfer the palmitate residue to Cys residues on target peptides. Versions of SELENOK containing either Ala or Cys residues in place of Sec were equivalently less effective than Sec at stabilizing the acyl-DHHC6 intermediate or promoting PAT activity. These data suggest that Sec₉₂ in SELENOK serves to stabilize the palmitoyl-DHHC6 intermediate by reducing hydrolyzation of the thioester bond until transfer of the palmitoyl group to the Cys residue on the target protein can occur.

T cell activation triggers metabolic reprogramming to meet increased demands for energy and metabolites required for cellular proliferation. Ethanolamine phospholipid synthesis has emerged as a regulator of metabolic shifts in stem cells and cancer cells, which led us to investigate its potential role during T cell activation. As selenoprotein I (SELENOI) is an enzyme participating in two metabolic pathways for the synthesis of phosphatidylethanolamine (PE) and plasmenyl PE, we generated SELENOI-deficient mouse models to determine loss-of-function effects on metabolic reprogramming during T cell activation. Ex vivo and in vivo assays were carried out along with metabolomic, transcriptomic, and protein analyses to determine the role of SELENOI and the ethanolamine phospholipids synthesized by this enzyme in cell signaling and metabolic pathways that promote T cell activation and proliferation. SELENOI knockout (KO) in mouse T cells led to reduced de novo synthesis of PE and plasmenyl PE during activation and impaired proliferation. SELENOI KO did not affect T cell receptor signaling, but reduced activation of the metabolic sensor AMPK. AMPK was inhibited by high [ATP], consistent with results showing SELENOI KO causing ATP accumulation, along with disrupted metabolic pathways and reduced glycosylphosphatidylinositol (GPI) anchor synthesis/attachment CONCLUSIONS: T cell activation upregulates SELENOI-dependent PE and plasmenyl PE synthesis as a key component of metabolic reprogramming and proliferation.

Aims: Genome-wide association studies have shown an increased risk of type-2-diabetes (T2DM) in patients who carry single nucleotide polymorphisms in several genes. We investigated whether the same gene loci confer a risk for gestational diabetes mellitus (GDM) in women from Hawaii, and in particular, Pacific Islander and Filipino populations.Methods: Blood was collected from 291 women with GDM and 734 matched non-diabetic controls (Pacific Islanders: 71 GDM, 197 non-diabetic controls; Filipinos: 162 GDM, 395 controls; Japanese: 58 GDM, 142 controls). Maternal DNA was used to genotype and show allele frequencies of 25 different SNPs mapped to 18 different loci.Results: After adjusting for age, BMI, parity and gravidity by multivariable logistic regression, several SNPs showed significant associations with GDM and were ethnicity specific. In particular, SNPs rs1113132 (EXT2), rs1111875 (HHEX), rs2237892 (KCNQ1), rs2237895 (KCNQ1), rs10830963 (MTNR1B) and rs13266634 (SLC30A8) showed significant associations with GDM in Filipinos. For Japanese, SNPs rs4402960 (IGFBP2) and rs2237892 (KCNQ1) were significantly associated with GDM. For Pacific Islanders, SNPs rs10830963 (MTNR1B) and rs13266634 (SLC30A8) showed significant associations with GDM. Individually, none of the SNPs showed a consistent association with GDM across all three investigated ethnicities.Conclusion: Several SNPs associated with T2DM are found to confer increased risk for GDM in a multiethnic cohort in Hawaii.

TRAIL and IFNγ are promising anti-cancer cytokines and it has been shown that IFNγ may sensitize cancer cells to TRAIL. Adipose derived mesenchymal stem cells (ADSCs) are attractive vehicles for delivering anti-cancer agents. In this study, we evaluated the therapeutic potential of PhiC31 (φC31) recombinase and/or piggyBac transposase (pBt) modified ADSCs expressing either TRAIL, IFNγ, or co-expressing TRAIL/IFNγ in mouse models of melanoma. The expression and bioactivity of mouse IFNγ and TRAIL in φC31 and pBt modified cells were confirmed. We examined the effects of modified ADSCs on signal intensity of red fluorescence protein expressed by melanoma cells in subcutaneous tumors or established lung metastases and on survival (6 mice per group). We also conducted a flow cytometric analysis of systemic CD4+CD25+FOXP3+ T regulatory cells (Tregs) and histological analysis of melanoma tumors. Data were analyzed by Student t test, ANOVA, and log-rank tests. All statistical tests were two-sided. We demonstrated non-viral DNA-integrating vectors can be used for stable transgene expression. IFNγ inhibited melanoma cell growth in vitro probably via IFNγ-induced JAK/STAT1 signaling pathway activation. Murine TRAIL induced apoptosis in the human cell lines CAOV-4 and Ej-138, while MCF7 and B16F10 cells appeared to be insensitive to TRAIL. Treatment of melanoma cells with IFNγ did not influence their response to TRAIL. In contrast, results from in vivo studies showed that IFNγ-expressing ADSCs, engrafted into tumor stroma, inhibited tumor growth and angiogenesis, prevented systemic increase of Tregs, increased PD-L1 expression and CD8+ infiltration (but not interleukin-2+ cells), and prolonged the survival of mice (68 days, 95% confidence interval [CI] =52 to 86 days compared to 36 days, 95% CI =29 to 39 days for control, P < .001). For the first time, we employed DNA integrating vectors for safe and stable modification of MSCs. Our data indicate potential of non-virally modified IFNγ-expressing ADSCs for treatment of melanoma through direct effects of IFNγ. This study may have a significant role in the management of cancer in the future.

While miRs have been extensively studied in the context of malignancy and tumor progression, their functions in regulating T-cell activation are less clear. In initial studies, we found reduced levels of miR-15a/16 at 3 to 18 h post–T-cell receptor (TCR) stimulation, suggesting a role for decreased levels of this miR pair in shaping T-cell activation. To further explore this, we developed an inducible miR15a/16 transgenic mouse model to determine how elevating miR-15a/16 levels during early stages of activation would affect T-cell proliferation and to identify TCR signaling pathways regulated by this miR pair. Doxycycline (DOX)-induced expression of miR-15a/16 from 0 to 18 h post-TCR stimulation decreased ex vivo T-cell proliferation as well as in vivo antigen-specific T-cell proliferation. We also combined bioinformatics and proteomics approaches to identify the mitogen-activated protein kinase kinase 1 (MEK1) (Map2k1) as a target of miR-15a/16. MEK1 targeting by miR-15a/16 was confirmed using miR mimics that decreased Map2k1 mRNA containing the 3′-UTR target nucleotide sequence (UGCUGCUA) but did not decrease Map2k1 containing a mutated control sequence (AAAAAAAA). Phosphorylation of downstream signaling molecules, extracellular signal–regulated protein kinase 1/2 (ERK1/2) and Elk1, was also decreased by DOX-induced miR-15a/16 expression. In addition to MEK1, ERK1 was subsequently found to be targeted by miR-15a/16, with DOX-induced miR-15a/16 reducing total ERK1 levels in T cells. These findings show that TCR stimulation reduces miR-15a/16 levels at early stages of T-cell activation to facilitate increased MEK1 and ERK1, which promotes the sustained MEK1–ERK1/2–Elk1 signaling required for optimal proliferation.