Biology subjects

Nakajima, D.

Publications and source records attributed to Nakajima, D..

3 recordsLinked to original sources

bioRxiv2024

Ultra-deep proteomics by Thin-diaPASEF with a 60-cm long column system

Proteomics using mass spectrometry (MS) has significantly advanced, offering deep insights into complex proteomes. The timsTOF MS platform with its parallel accumulation-serial fragmentation (PASEF) technology has achieved high scan speeds and high-quality spectra. Bukers timsTOF HT, which features TIMS-XR technology, offers an improved dynamic range and analysis depth, supporting high sample loadings. Moreover, various improvements to the data-independent acquisition method based on the PASEF technology (diaPASEF) have been reported. Despite these advancements, most high-level deep proteomic reports are based on the Orbitrap Astral and Orbitrap Exploris 480, and analytical systems using timsTOF MS still require improvement. Here, Brukers timsTOF HT was used to validate and optimize key diaPASEF parameters, leading to the development of a Thin-diaPASEF method. This method provides a high quantitative accuracy and consistency. In our validation, 9,400 proteins were identified in a single shot from HEK cells (strictly controlled Protein false discovery rate < 1%), the highest number analyzed by the timsTOF MS series using standard human cultured cells. Furthermore, by combining Thin-diaPASEF with an improved Lycopersicon esculentum lectin method, over 5,000 proteins were identified in a 24-sample/d analysis, and we succeeded in constructing a system with high proteome coverage that can be used for biomarker discovery.

biochemistry↗

bioRxiv2023

Universal pretreatment development for low-input proteomics using Lauryl Maltose Neopentyl Glycol

In recent years, the demand for low-input proteomics, most notably single-cell proteomics (SCP), has increased. In this study, we developed a Lauryl Maltose Neopentyl Glycol (LMNG)-assisted sample preparation (LASP) method that suppresses the loss of proteins and peptides in samples by adding LMNG, a surfactant, to the digested solution and removing the LMNG simply via reversed phase solid-phase extraction. The advantage of removing LMNG during sample preparation for general proteomic analysis is that it prevents mass spectrometry (MS) contamination. When the LASP method was applied to the low-input SP3 method and on-bead digestion in immunoprecipitation-MS, the recovery of the digested peptides was greatly improved. Furthermore, we established a simple and operationally easy sample preparation method for SCP based on the LASP method (scpLASP) and identified a median of 1,175 proteins from a single HEK239F cell using liquid chromatography (LC)-MS/MS with a throughput of 80 samples per day.

biochemistry↗

bioRxiv2022

TRIAC disrupts cerebral thyroid hormone action via a negative feedback loop and heterogenous distribution among organs

3,3,5-triiodothyroacetic acid (TRIAC) is a metabolite of endogenous thyroid hormones (THs) that can bind to and activate TH receptors. As TRIAC was previously detected in sewage effluent, we aimed to investigate exogenous TRIACs potential for endocrine disruption. We administered either TRIAC or 3,3,5-triiodo-L-thyronine (LT3) to both euthyroid mice and 6-propyl-2-thiouracil-induced hypothyroid mice. In hypothyroid mice, TRIAC alleviated growth retardation, suppressed the hypothalamus-pituitary-thyroid (HPT) axis, and upregulated TH-responsive genes in the pituitary gland, liver, and heart. We observed that, unlike LT3, TRIAC does not upregulate the expression of TH-responsive genes in the cerebrum. Measurement of organ-specific TRIAC levels suggested that TRIAC was not efficiently trafficked into the cerebrum. Furthermore, by analyzing euthyroid mice, we found that cerebral TRIAC levels did not increase despite TRIAC administration at higher concentrations, whereas serum and cerebral TH levels were substantially decreased. Hence, TH-responsive genes in the cerebrum appear to be downregulated by TRIAC. In summary, TRIAC administration decreases circulating TH levels by suppressing the HPT axis, while the consequent attenuation of TH actions was compensated by TRIAC in peripheral tissues but not in the cerebrum due to the relative impermeability of the blood-brain barrier towards TRIAC. We verified that exogenous TRIAC disrupts TH actions in the cerebrum. This disruption is apparently due to the additive effects of circulating endogenous THs being depleted via a negative feedback loop involving the HPT axis and heterogenous distribution of TRIAC among different organs. Our findings indicate that environmental TRIAC poses a potential neurodevelopmental risk.

ecology↗