Repositioning of Cefuroxime as novel selective inhibitor of the thyroid hormone activating enzyme type 2 deiodinase

Leptin enhances the intracellular thyroid hormone activation in skeletal muscle to boost energy balance

Thyroid hormones (THs) are key modulators of energy metabolism and cross-talk with other endocrine and metabolic factors. Notably, leptin can increase hypothalamic control of TH synthesis as an adaptive metabolic response regulating body weight. In this study, we found that the TH signal is heightened in overweight humans and is lost with obesity. In mice, systemic and intracerebroventricular leptin injection induces the expression of type 2 deiodinase (D2), the TH-activating enzyme, in skeletal muscle. Mechanistically, leptin enhances the transcription of D2 by a STAT3- and α-melanocyte-stimulating hormone (α-MSH)/cyclic AMP (cAMP)-dependent regulation. Notably, mice lacking D2 or with a mutation in the TH receptor do not exhibit the metabolic effects of leptin, such as increased insulin sensitivity and oxygen consumption, indicating that leptin's peripheral metabolic effects in skeletal muscle are mediated by TH. These findings underscore the critical role of leptin in integrating the TH-induced metabolic activation, while also contributing to appetite suppression in response to perceived fat stores.

Thyroid Hormone Activation Regulates the Crosstalk between Breast Cancer and Mesenchymal Stem Cells

BACKGROUND

Thyroid Hormones (THs) critically impact human cancer. Although endowed with both tumor-promoting and inhibiting effects in different cancer types, excess of THs has been linked to enhanced tumor growth and progression. Breast cancer depends on the interaction between bulk tumor cells and the surrounding microenvironment in which mesenchymal stem cells (MSCs) exert powerful pro-tumorigenic activities.

METHODS

Primary human MSCs from healthy female donors were co-cultured with DIO2 knock out (D2KO) and wild type (WT) MCF7 breast cancer cells to assess cell growth, migration, invasion and the expression of known epithelial-mesenchymal transition (EMT)- and inflammation-related markers. Furthermore, a surgery-free intraductal delivery model, i.e., the Mouse-INtraDuctal (MIND) injection method, was used as a tool for in vivo characterization of breast tumor formation and progression.

RESULTS

In this study, we uncovered a novel role of THs in regulating the tumor-stroma crosstalk. MCF7 cells enhanced the intracellular activation of THs through the TH-activating enzyme, D2, fostering their EMT properties and the dialogue with MSCs. D2 inactivation reduced the invasiveness of MCF7 cells and their responsiveness to the pro-tumorigenic induction via MSCs, both in vivo and in vitro.

CONCLUSIONS

Thus, we argue that intracellular activation of THs via D2 is a critical requirement for invasive and metastatic conversion of breast cancer cells, advising the blocking of D2 as a potential therapeutic tool for cancer therapy.

Single-cell and bulk RNA sequencing reveal heterogeneity and diagnostic markers in papillary thyroid carcinoma lymph-node metastasis

PURPOSE

Papillary thyroid carcinoma (PTC) is characterized by lymph-node metastasis (LNM), which affects recurrence and prognosis. This study analyzed PTC LNM by single-cell RNA sequencing (scRNA-seq) data and bulk RNA sequencing (RNA-seq) to find diagnostic markers and therapeutic targets.

METHODS

ScRNA-seq data were clustered and malignant cells were identified. Differentially expressed genes (DEGs) were identified in malignant cells of scRNA-seq and bulk RNA-seq, respectively. PTC LNM diagnostic model was constructed based on intersecting DEGs using glmnet package. Next, PTC samples from 66 patients were used to validate the two most significant genes in the diagnostic model, S100A2 and type 2 deiodinase (DIO2) by quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and immunohistochemical (IHC). Further, the inhibitory effect of DIO2 on PTC cells was verified by cell biology behavior, western blot, cell cycle analysis, 5-ethynyl-2'-deoxyuridine (EdU) assay, and xenograft tumors.

RESULTS

Heterogeneity of PTC LNM was demonstrated by Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis. A total of 19 differential genes were used to construct the diagnostic model. S100A2 and DIO2 differ significantly at the RNA (p < 0.01) and protein level in LNM patient tissues (p < 0.001). And differed in PTC tissues with different pathologic typing (p < 0.001). Further, EdU (p < 0.001) and cell biology behavior revealed that PTC cells overexpressed DIO2 had reduced proliferative capacity. Cell cycle proteins were reduced and cells are more likely to be stuck in G2/M phase (p < 0.001).

CONCLUSIONS

This study explored the heterogeneity of PTC LNM using scRNA-seq. By combining with bulk RNA-seq data, diagnostic markers were explored and the model was established. Clinical diagnostic efficacy of S100A2 and DIO2 was validated and the treatment potential of DIO2 was discovered.

The histone methyltransferase SMYD1 is induced by thermogenic stimuli in adipose tissue

Aim: To study the expression of histone methyltransferase SMYD1 in white adipose tissue (WAT) and brown adipose tissue and during differentiation of preadipocytes to white and beige phenotypes. Methods: C57BL/6J mice fed a high-fat diet (and exposed to cold) and 3T3-L1 cells stimulated to differentiate into white and beige adipocytes were used. Results: SMYD1 expression increased in WAT of high-fat diet fed mice and in WAT and brown adipose tissue of cold-exposed mice, suggesting its role in thermogenesis. SMYD1 expression was higher in beige adipocytes than in white adipocytes, and its silencing leads to a decrease in mitochondrial content and in Pgc-1α expression. Conclusion: These data suggest a novel role for SMYD1 as a positive regulator of energy control in adipose tissue.

Thyroid Hormone Regulates the Lipid Content of Muscle Fibers, Thus Affecting Physical Exercise Performance

Skeletal muscle (SkM) lipid composition plays an essential role in physiological muscle maintenance and exercise performance. Thyroid hormones (THs) regulate muscle formation and fuel energy utilization by modulating carbohydrates and lipid and protein metabolism. The best-known effects of THs in SkM include the promotion of mitochondrial biogenesis, the fiber-type switch from oxidative to glycolytic fibers, and enhanced angiogenesis. To assess the role of THs on the lipidic composition of SkM fibers, we performed lipidomic analyses of SkM cells and tissues, glucose tolerance experiments, and exercise performance tests. Our data demonstrated that TH treatment induces remodeling of the lipid profile and changes the proportion of fatty acids in SkM. In brief, THs significantly reduced the ratio of stearic/oleic acid in the muscle similar to what is induced by physical activity. The increased proportion of unsaturated fatty acids was linked to an improvement in insulin sensitivity and endurance exercise. These findings point to THs as critical endocrine factors affecting exercise performance and indicate that homeostatic maintenance of TH signals, by improving cell permeability and receptor stability at the cell membrane, is crucial for muscle physiology.