Biology subjects

Bunn, D.

Publications and source records attributed to Bunn, D..

3 recordsLinked to original sources

bioRxiv2024

Inhibition of Soluble Epoxide Hydrolase Ameliorates Cerebral Blood Flow Autoregulation and Cognition in Alzheimer's Disease and Diabetes-Related Dementia Rat Models

Alzheimers Disease and Alzheimers Disease-related dementias (AD/ADRD) pose major global healthcare challenges, with diabetes mellitus (DM) being a key risk factor. Both AD and DM-related ADRD are characterized by reduced cerebral blood flow, although the exact mechanisms remain unclear. We previously identified compromised cerebral hemodynamics as early signs in TgF344-AD and type 2 DM-ADRD (T2DN) rat models. Genome-wide studies have linked AD/ADRD to SNPs in soluble epoxide hydrolase (sEH). This study explored the effects of sEH inhibition with TPPU on cerebral vascular function and cognition in AD and DM-ADRD models. Chronic TPPU treatment improved cognition in both AD and DM-ADRD rats without affecting body weight. In DM-ADRD rats, TPPU reduced plasma glucose and HbA1C levels. Transcriptomic analysis of primary cerebral vascular smooth muscle cells from AD rats treated with TPPU revealed enhanced pathways related to cell contraction, alongside decreased oxidative stress and inflammation. Both AD and DM-ADRD rats exhibited impaired myogenic responses and autoregulation in the cerebral circulation, which were normalized with chronic sEH inhibition. Additionally, TPPU improved acetylcholine-induced vasodilation in the middle cerebral arteries (MCA) of DM-ADRD rats. Acute TPPU administration unexpectedly caused vasoconstriction in the MCA of DM-ADRD rats at lower doses. In contrast, higher doses or longer durations were required to induce effective vasodilation at physiological perfusion pressure in both control and ADRD rats. Additionally, TPPU decreased reactive oxygen species production in cerebral vessels of AD and DM-ADRD rats. These findings provide novel evidence that chronic sEH inhibition can reverse cerebrovascular dysfunction and cognitive impairments in AD/ADRD, offering a promising avenue for therapeutic development.

molecular biology↗

bioRxiv2023

Fusion crystallization reveals the behavior of both the 1TEL crystallization chaperone and the TNK1 UBA domain

Human thirty-eight-negative kinase-1 (TNK1) is implicated in cancer progression. The TNK1-UBA domain binds polyubiquitin and plays a regulatory role in TNK1 activity and stability. Sequence analysis suggests an unusual architecture for the TNK1 UBA domain, but an experimentally-validated molecular structure is undetermined. To gain insight into TNK1 regulation, we fused the UBA domain to the 1TEL crystallization chaperone and obtained crystals diffracting as far as 1.53 [A]. A 1TEL search model enabled solution of the X-ray phases. GG and GSGG linkers allowed the UBA to reproducibly find a productive binding mode against its host 1TEL polymer and to crystallize at protein concentrations as low as 0.1 mg/mL. Our studies support a mechanism of TELSAM fusion crystallization and show that TELSAM fusion crystals require fewer crystal contacts than traditional protein crystals. Modeling and experimental validation suggest the UBA domain may be selective for both the length and linkages of polyubiquitin chains.

biochemistry↗

bioRxiv2021

TELSAM polymers accelerate crystallization of fused target proteins by stabilizing minimal crystal contacts and in the absence of direct inter-TELSAM contacts

We extend investigation into the usefulness of genetic fusion to TELSAM polymers as an effective protein crystallization strategy. We tested various numbers of the target protein fused per turn of the TELSAM helical polymer and various TELSAM-target connection strategies. We provide definitive evidence that: 1. A TELSAM-target protein fusion can crystallize more rapidly than the same target protein alone, 2. TELSAM-target protein fusions can form well-ordered, diffracting crystals using either flexible or rigid TELSAM-target linkers, 3. Well-ordered crystals can be obtained when either 2 or 6 copies of the target protein are presented per turn of the TELSAM helical polymer, 4. The TELSAM polymers themselves need not directly contact one another in the crystal lattice, and 5. Fusion to TELSAM polymer confers immense avidity to stabilize exquisitely weak inter-target protein crystal contacts. We report features of TELSAM-target protein crystals and outline future work needed to define the requirements for reliably obtaining optimal crystals of TELSAM-target protein fusions.

biochemistry↗