Biology subjects

Sunassee, K.

Publications and source records attributed to Sunassee, K..

3 recordsLinked to original sources

bioRxiv2025

Characterisation of the dual roles of senescent-like T cells that arise during healthy and unhealthy ageing

Ageing is accompanied by progressive remodelling of the immune system, but chronic metabolic disease may accelerate this process and drive qualitatively distinct forms of immune dysfunction. Here, we used type 2 diabetes (T2D) as a model of unhealthy immune ageing to identify a distinct population of CD8 TEMRA cells that accumulates in older individuals with T2D. These cells were highly differentiated, oligoclonally expanded and had shorter telomeres, consistent with an increased replicative history and premature senescence-like state. Unlike conventional TEMRA cells, which can preserve cytotoxic function through acquisition of NK-cell receptors, T2D-associated TEMRA cells showed reduced surface expression of KLRG1, NKG2D and NKG2A together with defective receptor recycling. TGF{beta}1 was elevated in T2D and reproduced several features of this phenotype in vitro, including increased TEMRA differentiation, reduced NK-receptor expression, altered receptor trafficking and induction of p21. Functionally, these cells displayed reduced TCR-triggered degranulation, correlating with impaired cytotoxicity and altered tissue distribution in individuals with T2D. Rather than providing effective immune surveillance, the accumulation of these highly differentiated TEMRA cells with diminished effector capacity may compromise immune function. Together, these findings identify a distinct senescent-like CD8 TEMRA state linking metabolic inflammation to dysregulated T cell differentiation.

immunology↗

bioRxiv2024

Dual agonism of sodium iodide symporter function in vivo

New approaches are urgently needed to enhance the radioiodide (RAI) ablation of aggressive and metastatic thyroid cancer. We recently discovered that valosin-containing protein inhibitors (VCPi) such as clotrimazole and disulfiram transiently block sodium iodide symporter (NIS) proteasomal degradation, hence promoting RAI uptake. However, poor bioavailability diminishes their potential impact in vivo. Following 3D modelling and iterative drug design we appraised 26 novel analogues of clotrimazole, as well as albumin nano-encapsulated copper-diethyldithiocarbamate [Cu(DDC)2-alb] - a stabilised reformulation of a disulfiram metabolite. While several clotrimazole analogues specifically increased RAI uptake, the greatest impact was observed with Cu(DDC)2-alb in thyroid cancer cells as well as human primary thyrocytes from patients with thyroid hyperplasia. NanoBRET assays revealed that Cu(DDC)2 enhanced the plasma membrane accumulation of NIS in living cells. In BALB/c mice, both intraperitoneal and intravenous administration of Cu(DDC)2-alb significantly enhanced thyroidal 99mTc-uptake. RNA-Seq revealed the surprising observation that Cu(DDC)2-alb induced key thyroid transcription factors. Accordingly, expression of PAX8 and NKX2.1 was upregulated in thyroid glands from drug treated mice, with NIS levels correlating closely to 99mTc-uptake. As Cu(DDC)2 inhibits the VCP cofactor NPL4, with VCP being critical to the proteostatic processing of NIS protein, we identify a new dual agonist of RAI uptake in vivo, with the potential to directly impact RAI therapy for patients with aggressive thyroid cancer.

cancer biology↗

bioRxiv2023

Dissecting endocytic mechanisms reveals new molecular targets to enhance sodium iodide symporter activity with clinical relevance to radioiodide therapy

The sodium/iodide symporter (NIS) frequently shows diminished plasma membrane (PM) targeting in differentiated thyroid cancer (DTC), resulting in suboptimal radioiodide (RAI) treatment and poor prognosis. The mechanisms which govern the endocytosis of NIS away from the PM are ill-defined. Here, we challenged the hypothesis that new mechanistic understanding of NIS endocytosis would facilitate prediction of patient outcomes and enable specific drug modulation of RAI uptake in vivo. Through mutagenesis, NanoBiT interaction assays, cell surface biotinylation assays, RAI uptake and NanoBRET, we identify an acidic dipeptide within the NIS C-terminus which mediates binding to the {sigma}2 subunit of the Adaptor Protein 2 (AP2) heterotetramer. We discovered that the FDA-approved drug chloroquine modulates NIS accumulation at the PM in a functional manner that is AP2 dependent. In vivo, chloroquine treatment of BALB/c mice significantly enhanced thyroidal uptake of 99mTc pertechnetate in combination with the histone deacetylase (HDAC) inhibitor SAHA, accompanied by increased thyroidal NIS mRNA. Bioinformatic analyses validated the clinical relevance of AP2 genes with disease-free survival in RAI-treated DTC, enabling construction of an AP2 gene-related risk score classifier for predicting recurrence. We propose that NIS internalisation is orchestrated by the interaction of a C-terminal diacidic motif with AP2{sigma}2, together with the proto-oncogene PBF acting via AP22. Given that NIS internalisation was specifically druggable in vivo, our data provide new translatable potential for improving RAI therapy using FDA-approved drugs in patients with aggressive thyroid cancer. SummaryWe delineate the role of endocytic genes in regulating NIS activity at the plasma membrane and highlight the potential for systemic targeting of endocytosis to enhance radioiodine effectiveness in radioiodine-refractory cancer cells.

cancer biology↗