Biology subjects

Kelly, T. J.

Publications and source records attributed to Kelly, T. J..

4 recordsLinked to original sources

bioRxiv2022

Epac2 in midbrain dopamine neurons contributes to cocaine reinforcement via facilitation of dopamine release

Repeated exposure to drugs of abuse results in an upregulation of cAMP signaling in the mesolimbic dopamine system, a molecular adaptation thought to be critically involved in the development of drug dependence. Exchange protein directly activated by cAMP (Epac2) is a major cAMP effector abundantly expressed in the brain. However, it remains unknown whether Epac2 contributes to cocaine reinforcement. Here, we report that Epac2 in the mesolimbic dopamine system promotes cocaine reinforcement via enhancement of dopamine release. Conditional knockout of Epac2 from midbrain dopamine neurons (Epac2-cKO) and the selective Epac2 inhibitor ESI-05 decreased cocaine self-administration in mice under both fixed-ratio and progressive-ratio reinforcement schedules and across a broad range of cocaine doses. In addition, Epac2-cKO led to reduced evoked dopamine release, whereas Epac2 agonism robustly enhanced dopamine release in the nucleus accumbens in vitro. This mechanism is central to the behavioral effects of Epac2 disruption, as chemogenetic activation of ventral tegmental area (VTA) dopamine neurons increased dopamine release and reversed the impairment of cocaine self-administration in Epac2-cKO mice. Conversely, chemogenetic inhibition of VTA dopamine neurons reduced dopamine release and cocaine self-administration in wild-type mice. Epac2-mediated enhancement of dopamine release may therefore represent a novel and powerful mechanism that contributes to cocaine reinforcement.

neuroscience↗

bioRxiv2022

Repurposing Live Attenuated Trivalent MMR Vaccine as Cost-effective Cancer Immunotherapy

Despite its rising promise, cancer immunotherapy remains out of reach for many patients because of the extensive cost of manufacturing immunotherapy products. In this study, we show that intratumoral injections of the trivalent measles, mumps, and rubella (MMR) live attenuated viral vaccine (LAVs) modulates a potent cytotoxic T-cell antitumor immune response, resulting in tumor growth inhibition and improved survival in syngeneic mouse models of hepatocellular carcinoma and colorectal cancer. Using an integrated transcriptomic and proteomic approach, we demonstrated that mechanistically, MMR exerts its antitumor activity by priming innate and adaptive antitumor immune responses, leading to immunologically coordinated cancer cells death. Our findings highlight a promising potential for LAVs, such as MMR, to be repurposed as cost-effective cancer immunotherapy.

immunology↗

bioRxiv2021

Chromosome specific telomere lengths and the minimal functional telomere revealed by nanopore sequencing

We developed a method to tag telomeres and measure telomere length by nanopore sequencing in the yeast S. cerevisiae. Nanopore allows long read sequencing through the telomere, subtelomere and into unique chromosomal sequence, enabling assignment of telomere length to a specific chromosome end. We observed chromosome end specific telomere lengths that were stable over 120 cell divisions. These stable chromosome specific telomere lengths may be explained by stochastic clonal variation or may represent a new biological mechanism that maintains equilibrium unique to each chromosomes end. We examined the role of RIF1 and TEL1 in telomere length regulation and found that TEL1 is epistatic to RIF1 at most telomeres, consistent with the literature. However, at telomeres that lack subtelomeric Y sequences, tel1{Delta} rif1{Delta} double mutants had a very small, but significant, increase in telomere length compared to the tel1{Delta} single mutant, suggesting an influence of Y elements on telomere length regulation. We sequenced telomeres in a telomerase-null mutant (est2{Delta}) and found the minimal telomere length to be around 75bp. In these est2{Delta} mutants there were many apparent telomere recombination events at individual telomeres before the generation of survivors, and these events were significantly reduced in est2{Delta} rad52{Delta} double mutants. The rate of telomere shortening in the absence of telomerase was similar across all chromosome ends at about 5 bp per generation. This new method gives quantitative, high resolution telomere length measurement at each individual chromosome end, suggests possible new biological mechanisms regulating telomere length, and provides capability to test new hypotheses.

molecular biology↗

bioRxiv2021

γδ intraepithelial lymphocytes facilitate pathological epithelial cell shedding via CD103-mediated granzyme release.

Excessive shedding of enterocytes into the intestinal lumen is observed in inflammatory bowel disease and is correlated with disease relapse. However, the mechanisms underlying this phenomenon remain unclear. Intraepithelial lymphocytes (IEL) expressing the {gamma}{delta} T-cell receptor (TCR) provide surveillance of the intestinal mucosa at steady-state, which is regulated, in part, by CD103. Intravital microscopy of lipopolysaccharide (LPS)-treated mice revealed that {gamma}{delta} IELs make extended contact with shedding enterocytes. These prolonged interactions require CD103 engagement by E-cadherin, as CD103 blockade significantly reduces LPS-induced shedding. Furthermore, we find that granzymes A and B, but not perforin, are required for cell shedding, and that these granzymes are released by {gamma}{delta} IELs both constitutively and following CD103/E-cadherin ligation. These findings indicate that extracellular granzyme facilitates shedding, likely through cleavage of extracellular matrix proteins. Our results uncover a previously unrecognized role for {gamma}{delta} IELs in facilitating pathological cell shedding in a CD103- and granzyme-dependent manner.

immunology↗