Biomedical subjects

Ming Jing

Publications and source records attributed to Ming Jing.

6 recordsLinked to original sources

PubMed2026

Integrated single-cell and bulk transcriptomic analysis identifies a novel senescent fibroblast subtype associated with poor prognosis in acral melanoma.

BACKGROUND: Acral melanoma (AM) exhibits significant intratumoral heterogeneity, but its tumor microenvironment (TME) and immune regulation remain unclear. This study aims to dissect TME heterogeneity and establish a prognostic model based on key cell subpopulations. METHODS: We collected AM single-cell RNA sequencing (scRNA-seq) and bulk RNA-seq data from the Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA). Unsupervised clustering, CellChat, and Scissor analysis were performed to characterize cellular heterogeneity, cell-cell communication, and prognosis-related cell subpopulations. Kaplan-Meier analysis was used to assess the prognostic value of key genes, which were further validated by multiplex immunohistochemistry (mIHC). RESULTS: In AM, Mel_C2, C7, and C9 with high SEMA6A and KIT expression were strongly linked to poor prognosis. We further identified a senescent fibroblast subpopulation (sCAF_CDKN2A) characterized by high fibroblast senescence signature (FSS) scores. Integrating Scissor analysis of fibroblast subtypes with bulk prognostic data, we identified COL3A1, VCAN, and KIT as prognosis-associated genes upregulated in poor-outcome-related fibroblast subsets. Cell-cell communication analysis revealed that sCAF_CDKN2A engages in an immunosuppressive network, interacting with regulatory T cells (Tregs) via MIF signaling and receiving signals from exhausted CD8+ T cells through PPIA-BSG interactions. Using transcription factor expression patterns from these fibroblast subtypes, we constructed a prognostic model that effectively stratified patients into distinct risk groups with significant differences in overall survival (OS). mIHC confirmed significantly higher protein levels of SEMA6A and COL3A1 in tumor tissues compared to matched normal tissues. CONCLUSIONS: We established a novel prognostic model for AM and identified sCAF_CDKN2A as an immunosuppressive senescent fibroblast subpopulation driving poor prognosis.

Acral melanoma↗

PubMed2006

Degradation of tyrosine phosphatase PTPN3 (PTPH1) by association with oncogenic human papillomavirus E6 proteins.

Oncoproteins from DNA tumor viruses associate with critical cellular proteins to regulate cell proliferation, survival, and differentiation. Human papillomavirus (HPV) E6 oncoproteins have been previously shown to associate with a cellular HECT domain ubiquitin ligase termed E6AP (UBE3A). Here we show that the E6-E6AP complex associates with and targets the degradation of the protein tyrosine phosphatase PTPN3 (PTPH1) in vitro and in living cells. PTPN3 is a membrane-associated tyrosine phosphatase with FERM, PDZ, and PTP domains previously implicated in regulating tyrosine phosphorylation of growth factor receptors and p97 VCP (valosin-containing protein, termed Cdc48 in Saccharomyces cerevisiae) and is mutated in a subset of colon cancers. Degradation of PTPN3 by E6 requires E6AP, the proteasome, and an interaction between the carboxy terminus of E6 and the PDZ domain of PTPN3. In transduced keratinocytes, E6 confers reduced growth factor requirements, a function that requires the PDZ ligand of E6 and that can in part be replicated by inhibiting the expression of PTPN3. This report demonstrates the potential of E6 to regulate phosphotyrosine metabolism through the targeted degradation of a tyrosine phosphatase.

Amino Acid Sequence↗

PubMed2006

Critical role of 5'-AMP-activated protein kinase in the stimulation of glucose transport in response to inhibition of oxidative phosphorylation.

5'-AMP-activated protein kinase (AMPK) functions as an energy sensor to provide metabolic adaptation under conditions of ATP depletion, such as hypoxia and inhibition of oxidative phosphorylation. Whether activation of AMPK is critical for stimulation of glucose transport in response to inhibition of oxidative phosphorylation is unknown. Here we found that treatment of Glut1-expressing Clone 9 cells with sodium azide (5 mM for 2 h) or the AMPK activator 5'-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR, 2 mM for 2 h) stimulated the rate of glucose transport by two- to fourfold. Use of small interference RNA (siRNA) directed against AMPKalpha(1) or AMPKalpha(1) + AMPKalpha(2) (total AMPKalpha) resulted in a significant inhibition of the glucose transport response and the content of phosphorylated AMPKalpha(1) + phosphorylated AMPKalpha(2) (total p-AMPKalpha) and phosphorylated acetyl-CoA carboxylase (p-ACC) in response to azide. Transfection with siRNA directed against AMPKalpha(2) did not affect the glucose transport response. The efficacy of transfection with siRNAs in reducing AMPK content was confirmed by Western blotting. Incubation of cells with compound C, an inhibitor of AMPK, abrogated the glucose transport response and abolished the increase in total p-AMPK in azide-treated or hypoxia-exposed cells. Simultaneous exposure to azide and AICAR did not augment the rate of transport in response to AICAR alone. There was no evidence of coimmunoprecipitation of total p-AMPKalpha with Glut1. However, LKB1 was associated with total p-AMPKalpha. We conclude that activation of AMPK plays both a sufficient and a necessary role in the stimulation of glucose transport in response to inhibition of oxidative phosphorylation.

AMP-Activated Protein Kinase Kinases↗

PubMed2005

Role of 5'-AMP-activated protein kinase in stimulation of glucose transport in response to inhibition of oxidative phosphorylation.

Glucose transport is stimulated in a variety of cells and tissues in response to inhibition of oxidative phosphorylation. However, the underlying mechanisms and mediating steps remain largely unknown. In the present study we first tested whether a decrease in the redox state of the cell per se and the resultant increase in generation of reactive oxygen species (ROS) lead to stimulation of glucose transport. Clone 9 cells (expressing the Glut1 isoform of facilitative glucose transporters) were exposed to azide, lactate, and ethanol for 1 h. Although all three agents stimulated glucose transport and increased cell NADH-to-NAD(+) ratio and phospho-ERK1/2, signifying increased ROS generation, the response to the stimuli was not blocked by N-acetyl-l-cysteine (an agent that counteracts ROS); moreover, the response to azide was not blocked by diamide (an intracellular sulfhydryl oxidizing agent). We then found that cell AMP-to-ATP and ADP-to-ATP ratios were increased and 5'-AMP-activated protein kinase (AMPK) was stimulated by all three agents, as evidenced by increased phosphorylation of AMPK and acetyl-CoA carboxylase. We conclude that although azide, lactate, and ethanol increase NADH-to-NAD(+) ratios and ROS production, their stimulatory effect on glucose transport is not mediated by increased ROS generation. However, all three agents increased cell AMP-to-ATP ratio and stimulated AMPK, making it likely that the latter pathway plays an important role in the glucose transport response.

AMP-Activated Protein Kinases↗

PubMed2004

Reversal of insulin resistance postpartum is linked to enhanced skeletal muscle insulin signaling.

The restoration of maternal insulin sensitivity postpartum represents an important physiological and metabolic adaptation in a woman's reproductive lifespan. The present study was conducted to examine the potential cellular mechanisms underlying the changes in insulin sensitivity from late pregnancy to postpartum in human skeletal muscle. Nine nonobese women (age, 32 +/- 2 yr; body mass index, 21.2 +/- 0.8 kg/m(2)) with normal glucose tolerance were studied during late pregnancy (30-36 wk) and again approximately 1 yr postpartum using a euglycemic-hyperinsulinemic clamp (5 mm glucose, 40 mU/m(2).min insulin) to determine insulin sensitivity. Biopsies of the vastus lateralis muscle were obtained in the basal state before each clamp. Insulin sensitivity improved by 74% from late pregnancy to 1 yr postpartum (5.5 +/- 0.6 vs. 9.6 +/- 0.9 mg/kg fat-free mass.min; P < 0.005). Skeletal muscle insulin receptor (IR) protein expression increased by 42% postpartum, as measured by ELISA (4.0 +/- 0.6 vs. 5.7 +/- 0.6 ng/g protein; P < 0.05) and by Western blotting of the IR beta-subunit (28.7 +/- 4.7 vs. 42.0 +/- 4.8 arbitrary units; P < 0.003). However, in vitro studies showed that when adjusted for IR concentration, maximal insulin-stimulated (100 nm) IR tyrosine phosphorylation (0.75 +/- 0.06 vs. 0.92 +/- 0.08 U) and IR tyrosine kinase activity (183.8 +/- 27.0 vs. 204.3 +/- 23.7 fmol ATP/ng IR) were unchanged. There was a 69% increase in IR substrate-1 (IRS-1) protein expression (P = 0.05) in muscle postpartum. In addition, the p85alpha regulatory subunit of phosphatidylinositol 3-kinase was markedly reduced by 55% (P < 0.02) postpartum. The change in insulin sensitivity from late pregnancy to postpartum correlated highly with the corresponding change in IRS-1 protein (r = 0.84; P < 0.007). Downstream signaling proteins, including total Akt and p70s6 kinase, and the glucose transporter protein GLUT-4, were similar at both time points. These data suggest that reduced IR tyrosine kinase activity is not a major factor in the IR of pregnancy in lean women with normal glucose tolerance. Rather, the reversal of insulin resistance 1 yr postpartum is accompanied by increased skeletal muscle IRS-1 along with a down-regulation of the p85alpha subunit of phosphatidylinositol 3-kinase. These changes may allow for greater p85/p110 binding to IRS-1 and play a significant physiological role in the underlying metabolic adaptation to normal human pregnancy and restoration of insulin sensitivity postpartum.

Adult↗

PubMed2002

Modulation of insulin signaling in human skeletal muscle in response to exercise.

Exercise is widely recommended for the treatment of obesity, insulin resistance, and type II diabetes mellitus. Recent discoveries in the molecular and cellular regulation of insulin-mediated glucose metabolism in skeletal muscle have provided a deeper understanding of how exercise modulates insulin action.

Diabetes Mellitus, Type 2↗