Journal of biochemistry最新文献

Human aldehyde dehydrogenase IV (hALDH4) role in the metabolism of aldehydic compounds is apodictic. Fisetin, a bioactive flavonoid, having myriad of pharmacological activities with inexhaustible therapeutic potentials. Howbeit, the interactive mechanism and inhibitory potential of fisetin on hALDH4 still remain unclear and untold. Here, multi-spectroscopic technique, molecular modelling and dynamic simulations were comprehensively explored to elucidate this. Fisetin quenched the intrinsic fluorescence of the hALDH4 and showed a significant inhibitory effect on the enzyme (IC50 = 17.45 μM) with kinetic inhibition constant, KI, of 25.97 μM. It reversibly inhibited the enzyme in a mixed competitive manner. The interaction, though predominantly electrostatic interaction, perturbed the intrinsic hALDH4 conformation by compromising the predominant α-helix structure. hALDH4 has one ligand competent site for fisetin with a binding constant (Ka) of 3.80 × 104 L·mol-1 at 25°C. The molecular docking and atomistic simulations demonstrated affinity of fisetin for hALDH4 causing the protein structural strain, resulting in unusual but stable conformations. These findings provided important insight into the kinetics and thermodynamics of fisetin and hALDH4 interaction; thus. shedding light on the potential treatment of hALDH-implicated pathological conditions.

The murine retrovirus integration site 1 (MRVI1) gene encodes an endoplasmic reticulum (ER)-associated membrane protein involved in calcium signalling, yet its molecular interaction network remains largely undefined. Here, we employed TurboID-based proximity labelling to construct the first comprehensive map of MRVI1-associated proteins in mammalian cells. This analysis identified >700 candidate interactors, including ER-localized factors and components of intracellular trafficking, consistent with the subcellular localization and signalling role of MRVI1. To investigate oncogenic modulation, we examined how co-expression of NPM-ALK-a constitutively active tyrosine kinase implicated in lymphoid malignancies-reshapes the MRVI1 interactome. Quantitative proteomics revealed that while the overall composition of MRVI1-associated proteins was largely preserved, a subset of interactions was selectively enhanced or attenuated by NPM-ALK. The association of MRVI1 with several signalling-related proteins was enhanced by NPM-ALK, including 12 proteins that have all been previously implicated in cancer-related pathways. In contrast, proteins whose interaction with MRVI1 was suppressed were functionally enriched in the Gene Ontology term 'negative regulation of apoptotic process'. Notably, anti-apoptotic regulators such as DDB1, PHB2 and NOTCH2 showed significantly reduced proximity labelling, suggesting that MRVI1 may participate in apoptosis-related networks disrupted during oncogenic transformation. Together, our findings demonstrate that MRVI1 forms a functionally diverse protein network that can be selectively remodelled by oncogenic signalling. This study not only uncovers potential mechanisms by which MRVI1 contributes to transformation but also provides a valuable proteomic resource for future investigation of MRVI1 function and regulation.

Microglia, the central nervous system's resident macrophages, are critical for immune defense, protecting neurons during infection. Their role in postnatal brain development, particularly after injury, remains unclear. Nucling, a protein up-regulated during cardiac muscle differentiation, regulates NF-κB, influencing apoptosis and cell proliferation. In this study, we examined the role of Nucling in microglial activation using wild-type (WT) and Nucling-knockout (KO) neonatal mice subjected to poly(I:C), a viral mimic. Poly(I:C) treatment increased Iba1-positive microglia in both genotypes; however, KO mice showed a significantly exaggerated response in both cortical and hippocampal regions. Furthermore, while proinflammatory M1 markers (iNOS, CD86, TNFα, IL-6) were upregulated in both WT and KO mice, the anti-inflammatory M2 marker Arginase 1 (Arg1) was induced in WT but significantly suppressed in KO mice, indicating impaired M2 polarization. These findings suggest that Nucling is essential for maintaining microglial polarization, supporting immunological processes against pathogens and aiding central nervous system development.

Rab GTPases are molecular switches that control intracellular vesicular transport by cycling between GDP- and GTP-bound states. Insects encode an insect-specific subset, RabX; Bombyx mori RabX6 (BmRabX6) has been implicated in testis development and neuropeptide secretion, but its structure and mechanism were unknown. Here we report the 3.1 Å crystal structure of BmRabX6 in complex with GDP and Mg2+ (PDB: 9VLB), the first structure of an insect-specific Rab GTPase. BmRabX6 adopts the canonical small GTPase fold with conserved P-loop and Switch I/II, and displays a GDP-binding mode similar to vertebrate Rabs. Two features distinguish BmRabX6. First, the catalytic glutamine required for GTP hydrolysis in typical Rabs is naturally replaced by methionine (Met69) and oriented away from the nucleotide, consistent with obligate GAP-assisted hydrolysis. Second, one residue of the hydrophobic effector-binding triad is histidine (His47), suggesting a potential shift toward a hydrophilic interface-mediated interaction distinct from canonical Rab-effector recognition. AlphaFold3-based complex modeling further identified BmH9J2P5 as a prioritized GTPase-activating protein (GAP) candidate interacting with BmRabX6. These adaptations suggest that BmRabX6 preserves core nucleotide cycling while employing divergent regulatory chemistry tuned to insect physiology. Our structure provides a framework for testing GAP dependence and effector specificity of RabX6 in reproductive and neuronal tissues and illustrates how strategic amino-acid substitutions diversify Rab function.

Type 2 diabetes, which is closely linked to obesity, results from complex genetic and environmental interactions. Despite high heritability estimates, genome-wide association studies have not fully explained the heritability, suggesting the involvement of epigenetic mechanisms. This review highlights two distinct genome-independent pathways for intergenerational transmission of diabetic risk: (1) epigenetic transmission via gametes, whereby parental exposures induce heritable epigenetic changes in germ cells, and (2) developmental programming, in which prenatal or early postnatal environments shape the metabolism of offspring. Both processes are increasingly understood to involve epigenetic modifications, including DNA methylation, histone modifications, and non-coding RNAs. These epigenetic modifications have been suggested to contribute to intergenerational disease transmission in both animal and human studies. Understanding these mechanisms is essential for developing preventive strategies targeting the intergenerational risk of metabolic diseases.

Pancreatic β cells maintain glucose homeostasis through insulin production, and their loss underlies both type 1 and type 2 diabetes. Among the signaling systems that govern β-cell biology, insulin and insulin-like growth factor (IGF) receptor pathways have long attracted attention as intrinsic modulators of β-cell growth, survival, and secretory competence. However, the physiological and pathological relevance of these receptors in β cells remains uncertain, reflecting model-specific discrepancies and the complex interplay between local autocrine and systemic endocrine effects. Recent analyses have expanded this view, revealing the coexistence of insulin receptor-dependent and insulin receptor-independent regulatory modules that govern β-cell adaptation to metabolic stress. Furthermore, molecular regulators, including inceptor and IGF2R, reshape our understanding of insulin/IGF receptor signaling as a flexible, adaptive network. Together, these insights suggest that precise modulation of receptor networks may hold the key to unlocking endogenous β-cell regenerative capacity.

Peroxisomes are dynamic organelles found in almost all eukaryotic cells and play a central role in intracellular metabolism. The number of peroxisomes is maintained through the balance of peroxisome biogenesis and degradation. Peroxisomes multiply by growth and division from preexisting peroxisomes but have also been shown to be synthesized de novo under experimental conditions. During de novo synthesis, pre-peroxisome vesicles mature in a stepwise process into functional peroxisomes. While the growth and division cycle is well studied, de novo synthesis, including whether it physiologically occurs, remains poorly understood. Although studies using several models have been proposed, the origin of the membranes required for peroxisome assembly remain controversial. This review provides an overview of the studies on de novo synthesis of peroxisomes in multiple organisms and discusses the evolutionary insights and biological meanings of peroxisome de novo synthesis.