The N⁶-methyladenosine methyltransferase METTL16 enables erythropoiesis through safeguarding genome integrity

RNA修飾による赤血球造血制御機構を解明 --RNAのメチル化がDNA修復に必要--. 京都大学プレスリリース. 2022-11-10.Mice show METTL in DNA blood repair: RNA methylation shows important role in erythropoiesis. 京都大学プレスリリース. 2022-11-25.During erythroid differentiation, the maintenance of genome integrity is key for the success of multiple rounds of cell division. However, molecular mechanisms coordinating the expression of DNA repair machinery in erythroid progenitors are poorly understood. Here, we discover that an RNA N⁶-methyladenosine (m⁶A) methyltransferase, METTL16, plays an essential role in proper erythropoiesis by safeguarding genome integrity via the control of DNA-repair-related genes. METTL16-deficient erythroblasts exhibit defective differentiation capacity, DNA damage and activation of the apoptotic program. Mechanistically, METTL16 controls m⁶A deposition at the structured motifs in DNA-repair-related transcripts including Brca2 and Fancm mRNAs, thereby upregulating their expression. Furthermore, a pairwise CRISPRi screen revealed that the MTR4-nuclear RNA exosome complex is involved in the regulation of METTL16 substrate mRNAs in erythroblasts. Collectively, our study uncovers that METTL16 and the MTR4-nuclear RNA exosome act as essential regulatory machinery to maintain genome integrity and erythropoiesis

Malnutrition in Alzheimer's Disease, Dementia with Lewy Bodies, and Frontotemporal Lobar Degeneration: Comparison Using Serum Albumin, Total Protein, and Hemoglobin Level.

Malnutrition among dementia patients is an important issue. However, the biochemical markers of malnutrition have not been well studied in this population. The purpose of this study was to compare biochemical blood markers among patients with Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and frontotemporal lobar degeneration (FTLD). A total of 339 dementia outpatients and their family caregivers participated in this study. Low serum albumin was 7.2 times more prevalent among patients with DLB and 10.1 times more prevalent among those with FTLD than among those with AD, with adjustment for age. Low hemoglobin was 9.1 times more common in female DLB patients than in female AD patients, with adjustment for age. The levels of biochemical markers were not significantly correlated with cognitive function. Family caregivers of patients with low total protein, low albumin, or low hemoglobin were asked if the patients had loss of weight or appetite; 96.4% reported no loss of weight or appetite. In conclusion, nutritional status was worse in patients with DLB and FTLD than in those with AD. A multidimensional approach, including blood testing, is needed to assess malnutrition in patients with dementia

Exo-Cleavable Linkers: A Paradigm Shift for Enhanced Stability and Therapeutic Efficacy in Antibody-Drug Conjugates

Customized drug delivery systems have become paramount in the rapidly evolving field of precision medicine, and at the forefront of advances in this regard, antibody-drug conjugates (ADCs) present a symbiotic fusion of cytotoxic payloads and monoclonal antibodies (mAbs) facilitated by intricate chemical linkers. The search for ideal linkers that can dexterously provide the dual functionalities of enhancing circulatory stability and facilitating the effective release of the tumor payload is a present and formidable challenge. The valine-citrulline (Val-Cit) linker, which is used in a wide range of ADCs, despite its approval by the Food and Drug Administration, is associated with several inherent drawbacks, including hydrophobicity-induced aggregation, limited payload capacity, and premature payload release. This study presents a paradigm shift from the conventional linear linker archetype by introducing an exo-linker avant-garde approach that repositions the cleavable peptide linker at the exo-position of the PAB moiety. This molecular refinement not only offered the possibility to overcome the intrinsic drawbacks of the Val-Cit platform, but also significantly improved ADC stability, therapeutic efficacy, and pharmacokinetics. In vitro and in vivo biological evaluations, confirmed that ADCs designed using the exo-linker blueprint significantly attenuated premature payload release, while increasing the drug-to-antibody ratio, even with hydrophobic payloads, and this without inducing pronounced aggregation. Therefore, the fabricated exo-linker represents a significant improvement with respect to traditional Val-Cit ADCs. Moreover, under the influence of enzymes, such as carboxylesterases and human neutrophil elastase, the payload remained stably conjugated to the ADC, underscoring a favorable safety profile and highlighting potential for clinical translatability. Thus, our findings also demonstrate the potential of the novel exo-linker paradigm as well as the profound implications of nuanced molecular modifications for reshaping ADC design and functionality

AJICAP Second Generation: Improved Chemical Site-Specific Conjugation Technology for Antibody-Drug Conjugate Production

The site-directed chemical conjugation of antibodies remains an area of great interest and active efforts within the antibody-drug conjugate (ADC) community. We previously reported a unique site modification using a class of immunoglobulin-G (IgG) Fc-affinity reagents to establish a versatile, streamlined, and site-selective conjugation of native antibodies to enhance the therapeutic index of the resultant ADCs. This methodology, termed “AJICAP,” successfully modified Lys248 of native antibodies to produce site-specific ADC with a wider therapeutic index than the Food and Drug Administration-approved ADC, Kadcyla. However, the long reaction sequences, including the reduction-oxidation (redox) treatment, increased. In this manuscript, we aimed to present an updated Fc-affinity-mediated site-specific conjugation technology named “AJICAP second generation” without redox treatment utilizing a "one-pot” antibody modification reaction. The stability of Fc affinity reagents was improved owing to structural optimization, enabling the production of various ADCs without aggregation. In addition to Lys248 conjugation, Lys288 conjugated ADCs with homogenous drug-to-antibody ratio of 2 were produced using this technology after a proper modification of the spacer linkage of Fc-affinity peptide reagents. These two conjugation technologies were used to produce over 20 ADCs from several combinations of antibodies and drug linkers. The in vivo profile of Lys248 and Lys288 conjugated ADCs was also compared. Furthermore, non-traditional ADC applications, such as antibody-protein conjugates and antibody-oligonucleotide conjugates, were performed. These results strongly indicate that this Fc affinity conjugation approach is a promising strategy for manufacturing site-specific antibody conjugates

Prevalence of abnormal blood marker values (%).

<p>Prevalence of abnormal blood marker values (%).</p

Odds ratio of abnormal levels of biochemical blood markers (reference = AD).

<p>Odds ratio of abnormal levels of biochemical blood markers (reference = AD).</p

Differences of Behavioral and Psychological Symptoms of Dementia in Disease Severity in Four Major Dementias

<div><p>Background/Aims</p><p>Behavioral and psychological symptoms of dementia (BPSDs) negatively impact the prognosis of dementia patients and increase caregiver distress. The aims of this study were to clarify the differences of trajectories of 12 kinds of BPSDs by disease severity in four major dementias and to develop charts showing the frequency, severity, and associated caregiver distress (ACD) of BPSDs using the data of a Japan multicenter study (J-BIRD).</p><p>Methods</p><p>We gathered Neuropsychiatric Inventory (NPI) data of patients with Alzheimer’s disease (AD; n = 1091), dementia with Lewy bodies (DLB; n = 249), vascular dementia (VaD; n = 156), and frontotemporal lobar degeneration (FTLD; n = 102) collected during a 5-year period up to July 31, 2013 in seven centers for dementia in Japan. The NPI composite scores (frequency × severity) of 12 kinds of items were analyzed using a principal component analysis (PCA) in each dementia. The factor scores of the PCA were compared in each dementia by disease severity, which was determined with Clinical Dementia Rating (CDR).</p><p>Results</p><p>Significant increases with higher CDR scores were observed in 1) two of the three factor scores which were loaded for all items except euphoria in AD, 2) two of the four factor scores for apathy, aberrant motor behavior (AMB), sleep disturbances, agitation, irritability, disinhibition, and euphoria in DLB, and 3) one of the four factor scores for apathy, depression, anxiety, and sleep disturbances in VaD. However, no increases were observed in any of the five factor scores in FTLD.</p><p>Conclusions</p><p>As dementia progresses, several BPSDs become more severe, including 1) apathy and sleep disturbances in AD, DLB, and VaD, 2) all of the BPSDs except euphoria in AD, 3) AMB, agitation, irritability, disinhibition, and euphoria in DLB, and 4) depression and anxiety in VaD. Trajectories of BPSDs in FTLD were unclear.</p></div