1: A highly photostable and bright green fluorescent protein.
Science of the Month - June 2022
Nature Biotechnology.
2022 Apr 25. doi: 10.1038/s41587-022-01278-2.
Hirano M, Ando R, Shimozono S, Sugiyama M, Takeda N, Kurokawa H, Deguchi R, Endo K, Haga K, Takai-Todaka R, Inaura S, Matsumura Y, Hama H, Okada Y, Fujiwara T, Morimoto T, Katayama K, Miyawaki A.
In fluorescence live imaging, increasing the excitation light intensity allows for brighter (or finer in super-resolution) observation of labeled structures. However, increased excitation light intensity leads to photobleaching of the dye or cell damage. If the former issue, photobleaching, could be resolved, how would the spatiotemporal scale of our fluorescence imaging expand? This paper presents an answer to this question using a photostable fluorescent protein derived from a jellyfish. We achieved high-speed, long-term, wide-field, super-resolution imaging of organelles without fear of photobleaching. By thoroughly implementing "no intervals" during observation, we were able, for example, to quantitatively analyze the tremors of the tubular structures of the endoplasmic reticulum. There are limits to the approach of increasing the expression level of fluorescent proteins to overcome the photobleaching problem. The time has come to consider how to brightly observe structures labeled with low-copy-number dyes. Photobleaching research is extremely difficult (the reasons for this are detailed in the supplementary text of the paper). For over a decade, I had been careful to avoid getting bogged down in the photobleaching problem, but I had decided that if, by some chance, I obtained a highly photostable fluorescent protein, I would name it StayGold. Having now delved into it, I am reminded once again. Indeed, photobleaching is a problem that one must tackle with the expectation of entering a labyrinth.
(Atsushi Miyawaki, Deputy Director, RIKEN Center for Brain Science, 66th)
2: Topical pH Sensing NIR Fluorophores for Intraoperative Imaging and Surgery of Disseminated Ovarian Cancer.
Advanced Sciene.
Yokomizo S, Henary M, Buabeng ER, Fukuda T, Monaco H, Baek Y, Manganiello S, Wang H, Kubota J, Ulumben AD, Lv X, Wang C, Inoue K, Fukushi M, Kang H, Bao K, Kashiwagi S, Choi HS.
In the March issue of this year, we featured the development of an intravenously injectable near-infrared fluorescent dye for intraoperative imaging to accurately identify the location of micro-ovarian cancers. With this systemic administration, there are concerns about the large dosage and significant side effects. Co-corresponding author Kashiwagi (76th), through joint research with chemistry groups at Massachusetts General Hospital and Georgia State University that design and synthesize fluorescent molecules, has also developed a "spray-on fluorescent dye for the surgical field." From candidate molecules created by adding charges or chemical modifications to the heptamethine structure, typified by indocyanine green (ICG) which is widely used in intraoperative imaging, we screened for a dye that exhibits increased fluorescence in the low-pH tumor microenvironment, is selectively taken up by organic anion-transporting polypeptides (OATPs) that are highly expressed in cancer tissues, and tends to be retained within cells. When a very small amount of this was sprayed directly onto a mouse model of disseminated ovarian cancer, micro-cancers could be detected with high definition from just 10 minutes after application for up to 4 hours. This dye is considered simple, economical, and highly safe, and we are exploring its expanded application to other superficial cancer surgeries and endoscopic examinations.
(Satoshi Kashiwagi, Department of Obstetrics and Gynecology, 76th)
3: Dopaminergic dysfunction and excitatory/inhibitory imbalance in treatment-resistant schizophrenia and novel neuromodulatory treatment.
Molecular Psychiatry.
2022 Apr 20. doi: 10.1038/s41380-022-01572-0.
Yokomizo S, Henary M, Buabeng ER, Fukuda T, Monaco H, Baek Y, Manganiello S, Wang H, Kubota J, Ulumben AD, Lv X, Wang C, Inoue K, Fukushi M, Kang H, Bao K, Kashiwagi S, Choi HS.
Schizophrenia is a chronic disorder (prevalence rate of 1%) characterized by hallucinations, delusions, avolition, flattened affect, and cognitive impairment. The mainstay of treatment is antipsychotic drugs with dopamine receptor antagonist effects, discovered half a century ago, which forms the basis of the dopamine hypothesis of schizophrenia. However, existing antipsychotics are ineffective for about 30% of patients, and their pathophysiology cannot be explained by the conventional dopamine hypothesis alone. Currently, the excitatory/inhibitory imbalance hypothesis is gaining attention as a hypothesis to explain the pathophysiology of schizophrenia. This hypothesis is based on the effects of glutamate receptor antagonists, which induce schizophrenia-like symptoms in healthy individuals, and posits that abnormalities in the excitatory glutamatergic nervous system impair the downstream inhibitory GABAergic nervous system, which in turn disinhibits further downstream neural systems, leading to diverse symptoms. Masataka Wada (4th year, Doctoral Programs) from the Department of Neuropsychiatry has published an opinion-based review in Molecular Psychiatry, one of the top journals in psychiatric research. The review discusses treatment-resistant schizophrenia from the perspectives of the dopamine hypothesis and the excitatory/inhibitory imbalance hypothesis, and outlines prospects for the development of novel neuromodulation (a technique that uses electricity or magnetism to change or regulate neural activity to improve symptoms and disabilities caused by functional abnormalities in the nervous system). This work is the result of discussions on current findings with clinical and basic researchers in Japan and abroad, conducted by Wada, who is currently developing transcranial magnetic stimulation therapy for treatment-resistant depression under the guidance of Yoshihiro Noda (Project Associate Professor, Department of Neuropsychiatry). Specifically, it discusses treatment-resistant schizophrenia based on the two pathophysiological hypotheses mentioned above, introduces the current findings of neuromodulation research, and proposes the development of deep phenotyping through comprehensive biomarker measurement, biotyping using multivariate analysis and machine learning, and closed-loop neuromodulation for biotypes using biomarkers. It is an interesting piece, and I hope you will take the time to read it.
(Shinichiro Nakajima, Department of Neuropsychiatry, 81st)