Crosstalk Between Abnormal TSHR Signaling Activation and PTEN/PI3K in the Dedifferentiation of Thyroid Cancer Cells

Puerarin inhibits inflammation and oxidative stress in female BALB/c mouse models of Graves' disease

Background

Graves' disease (GD) is an autoimmune thyroid disorder. Our previous study has demonstrated a significant decrease in flavone levels among children with GD compared to the control group. Puerarin, a well-known flavonoid with anti-inflammatory and antioxidant properties. We wanted to investigate its potential impact on GD pathogenesis, aiming to determine whether increasing puerarin intake could prevent or delay the onset of GD.

Methods

Adenovirus with TSHR-289 subunit was used to establish a GD mice model, and mice were intragastrically administered with puerarin or sterilized water daily. Thyroid function and inflammatory cytokine levels were quantified using ELISA, lymphocyte subsets were analyzed via flow cytometry, oxidative stress (OS) markers were measured with a microplate reader, and the expression of pertinent signaling pathway proteins were assessed by Western blot.

Results

The results demonstrated that puerarin treatment significantly decreased thyroxin levels and alleviated thyroid pathological changes in GD mice. Furthermore, the immune imbalance of GD mice was improved, as evidenced by reduced inflammatory indexes, elevated antioxidant levels, and decreased malondialdehyde (MDA) levels compared to untreated GD mice. Puerarin-treated GD mice exhibited significantly lower expressions of heat shock protein (HSP): HSP70, HSP90, phosphorylated extracellular regulated kinases (p-ERK) and phosphorylated protein kinase B (p-AKT) than untreated GD mice. Moreover, low dosage puerarin (400 mg/kg) was associated with a better protective effect than high dosage (1,200 mg/kg).

Conclusions

Puerarin may have the potential to mitigate GD by inhibiting inflammatory and OS, through downregulating the expression of HSP70 and HSP90 and suppressing the activation of the PI3K/AKT/ERK signaling pathway. Furthermore, a lower dose exhibited superior protective effects compared to a higher dose.

Interaction kinetics between p115-RhoGEF and Gα13 are determined by unique molecular interactions affecting agonist sensitivity

The three RH-RhoGEFs (Guanine nucleotide exchange factors) p115-RhoGEF, LARG (leukemia-associated RhoGEF) and PDZ-RhoGEF link G-protein coupled receptors (GPCRs) with RhoA signaling through activation of Gα_12/13. In order to find functional differences in signaling between the different RH-RhoGEFs we examined their interaction with Gα₁₃ in high spatial and temporal resolution, utilizing a FRET-based single cell assay. We found that p115-RhoGEF interacts significantly shorter with Gα₁₃ than LARG and PDZ-RhoGEF, while narrowing the structural basis for these differences down to a single amino acid in the rgRGS domain of p115-RhoGEF. The mutation of this amino acid led to an increased interaction time with Gα₁₃ and an enhanced agonist sensitivity, comparable to LARG, while mutating the corresponding amino acid in Gα₁₃ the same effect could be achieved. While the rgRGS domains of RH-RhoGEFs showed GAP (GTPase-activating protein) activity towards Gα₁₃ in vitro, our approach suggests higher GAP activity of p115-RhoGEF in intact cells.

Apatinib Through Activating the RhoA/ROCK Signaling Pathway to Cause Dysfunction of Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) are associated with differentiated, organized, and contractile phenotype under the effect of various types of physiological conditions those are associated with migratory, proliferative, and synthetic phenotype under the effect of various types of stimuli, which dysfunction drives many cardiovascular diseases. Abnormal cell proliferation and invasion of VSMCs are among the primary causes of hypertension. Apatinib is a small-molecule tyrosine kinase inhibitor (TKI) that highly selectively binds to and strongly inhibits VEGFR-2. Previous studies have confirmed that the TKIs can raise blood pressure through RhoA/ROCK pathway. LARG is a key gene in the RhoA/ROCK pathway and plays a critical role in the continuous vasoconstriction function because it regulates part of signal transduction in VSMCs. In this study, an in vitro experiment was conducted to observe that apatinib caused dysfunction of MOVAS cells through the RhoA/ROCK signalling pathway and Y27632, a nonspecific ROCK inhibitor, and knockout of LARG gene can improve the proliferation, antiapoptosis, oxidative stress, and mitochondrial autophagy of apatinib-induced MOVAS cells. These findings suggest that activation of the RhoA/ROCK signalling pathway could be the underlying mechanism of apatinib-induced dysfunction of MOVAS cells, while ROCK inhibitor and knockout of LARG gene have potential therapeutic value.

The Mysterious Universe of the TSH Receptor

The thyroid-stimulating hormone receptor (TSH-R) is predominantly expressed in the basolateral membrane of thyrocytes, where it stimulates almost every aspect of their metabolism. Several extrathyroidal locations of the receptor have been found including: the pituitary, the hypothalamus, and other areas of the central nervous system; the periorbital tissue; the skin; the kidney; the adrenal; the liver; the immune system cells; blood cells and vascular tissues; the adipose tissue; the cardiac and skeletal muscles, and the bone. Although the functionality of the receptor has been demonstrated in most of these tissues, its physiological importance is still a matter of debate. A contribution to several pathological processes is evident in some cases, as is the case of Grave's disease in its multiple presentations. Conversely, in the context of other thyroid abnormalities, the contribution of the TSH-R and its ligand is still a matter of debate. This article reviews the several different sites of expression of the TSH-R and its potential role in both physiological and pathological processes.