• Molecules and Cells
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• 제44권8호
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• pp.591-601
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• 2021

Cilia are highly specialized organelles that extend from the cell membrane and function as cellular signaling hubs. Thus, cilia formation and the trafficking of signaling molecules into cilia are essential cellular processes. TULP3 and Tubby (TUB) are members of the tubby-like protein (TULP) family that regulate the ciliary trafficking of G-protein coupled receptors, but the functions of the remaining TULPs (i.e., TULP1 and TULP2) remain unclear. Herein, we explore whether these four structurally similar TULPs share a molecular function in ciliary protein trafficking. We found that TULP3 and TUB, but not TULP1 or TULP2, can rescue the defective cilia formation observed in TULP3-knockout (KO) hTERT RPE-1 cells. TULP3 and TUB also fully rescue the defective ciliary localization of ARL13B, INPP5E, and GPR161 in TULP3 KO RPE-1 cells, while TULP1 and TULP2 only mediate partial rescues. Furthermore, loss of TULP3 results in abnormal IFT140 localization, which can be fully rescued by TUB and partially rescued by TULP1 and TULP2. TUB's capacity for binding IFT-A is essential for its role in cilia formation and ciliary protein trafficking in RPE-1 cells, whereas its capacity for PIP₂ binding is required for proper cilia length and IFT140 localization. Finally, chimeric TULP1 containing the IFT-A binding domain of TULP3 fully rescues ciliary protein trafficking, but not cilia formation. Together, these two TULP domains play distinct roles in ciliary protein trafficking but are insufficient for cilia formation in RPE-1 cells. In addition, TULP1 and TULP2 play other unknown molecular roles that should be addressed in the future.

• Molecules and Cells
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• 제43권6호
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• pp.501-508
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• 2020

In eukaryotes, membraneous cellular compartmentation essentially requires vesicle trafficking for communications among distinct organelles. A donor organelle-generated vesicle releases its cargo into a target compartment by fusing two distinct vesicle and target membranes. Vesicle fusion, the final step of vesicle trafficking, is driven intrinsically by complex formation of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). Although SNAREs are well-conserved across eukaryotes, genomic studies revealed that plants have dramatically increased the number of SNARE genes than other eukaryotes. This increase is attributed to the sessile nature of plants, likely for more sensitive and harmonized responses to environmental stresses. In this review, we therefore try to summarize and discuss the current understanding of plant SNAREs function in responses to biotic and abiotic stresses.

• BMB Reports
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• 제47권7호
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• pp.361-368
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• 2014

Lipid components in biological membranes are essential for maintaining cellular function. Phosphoinositides, the phosphorylated derivatives of phosphatidylinositol (PI), regulate many critical cell processes involving membrane signaling, trafficking, and reorganization. Multiple metabolic pathways including phosphoinositide kinases and phosphatases and phospholipases tightly control spatio-temporal concentration of membrane phosphoinositides. Metabolizing enzymes responsible for PI 4,5-bisphosphate (PI(4,5)P2) production or degradation play a regulatory role in Toll-like receptor (TLR) signaling and trafficking. These enzymes include PI 4-phosphate 5-kinase, phosphatase and tensin homolog, PI 3-kinase, and phospholipase C. PI(4,5)P2 mediates the interaction with target cytosolic proteins to induce their membrane translocation, regulate vesicular trafficking, and serve as a precursor for other signaling lipids. TLR activation is important for the innate immune response and is implicated in diverse pathophysiological disorders. TLR signaling is controlled by specific interactions with distinct signaling and sorting adaptors. Importantly, TLR signaling machinery is differentially formed depending on a specific membrane compartment during signaling cascades. Although detailed mechanisms remain to be fully clarified, phosphoinositide metabolism is promising for a better understanding of such spatio-temporal regulation of TLR signaling and trafficking.

• Molecules and Cells
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• 제22권2호
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• pp.210-219
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• 2006

Dynamin-related protein 2A (AtDRP2A, formally ADL6), a member of the dynamin family, is critical for protein trafficking from the TGN to the central vacuole. However, the mechanism controlling its activity is not well understood in plant cells. We isolated Arabidopsis sec13 homolog1 (AtSeh1) that interacts with AtDRP2A by a yeast two-hybrid screening. AtSeh1 has four WD40 motifs and amino acid sequence homology to Sec13, a component of COPII vesicles. Coimmunoprecipitation and protein pull-down experiments demonstrated specific interaction between AtSeh1 and AtDRP2A. AtSeh1 bound to the pleckstrin homology domain of AtDRP2A in competition with the C-terminal domain of the latter, and this resulted in inhibition of the interaction between AtDRP2A and PtdIns3P in vitro. AtSeh1 localized to multiple locations: the nucleus, the prevacuolar compartment and the Golgi complex. Based on these results we propose that AtSeh1 plays a role in regulating cycling of AtDRP2A between membrane-bound and soluble forms.

• Molecules and Cells
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• 제43권12호
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• pp.1002-1010
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• 2020

Cilia are important eukaryotic cellular compartments required for diverse biological functions. Recent studies have revealed that protein targeting into the proper ciliary subcompartments is essential for ciliary function. In Drosophila chordotonal cilium, where mechano-electric transduction occurs, two transient receptor potential (TRP) superfamily ion channels, TRPV and TRPN, are restricted to the proximal and distal subcompartments, respectively. To understand the mechanisms underlying the sub-ciliary segregation of the two TRPs, we analyzed their localization under various conditions. In developing chordotonal cilia, TRPN was directly targeted to the ciliary tip from the beginning of its appearance and was retained in the distal subcompartment throughout development, whereas the ciliary localization of TRPV was considerably delayed. Lack of intraflagella transport-related proteins affected TRPV from the initial stage of its pre-ciliary trafficking, whereas it affected TRPN from the ciliary entry stage. The ectopic expression of the two TRP channels in both ciliated and non-ciliated cells revealed their intrinsic properties related to their localization. Taken together, our results suggest that sub-ciliary segregation of the two TRP channels relies on their distinct intrinsic properties, and begins at the initial stage of their pre-ciliary trafficking.

• Molecules and Cells
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• 제38권11호
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• pp.936-940
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• 2015

Synapsins were the first presynaptic proteins identified and have served as the flagship of the presynaptic protein field. Here we review recent studies demonstrating that different members of the synapsin family play different roles at presynaptic terminals employing different types of synaptic vesicles. The structural underpinnings for these functions are just beginning to be understood and should provide a focus for future efforts.

• Archives of Pharmacal Research
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• 제28권1호
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• pp.93-99
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• 2005

Intracellular trafficking of transferrin-conjugated dimethyldioctadecyl-ammonium bromide liposome $(T_f-liposome)/DNA$ complexes in HeLa cells was studied using the double-labeled fluorescence technique and confocal microscopy. The size of the $T_f-liposome/DNA$ complex was about 367 nm in diameter and the zeta-potential of it at a 5:1 (w/w) ratio was almost neutral. The intracellular pathway of the $T_f-liposome/DNA$ complex, noted as green (FITC), red (rhodamine) or yellow (FITC + rhodamine) fluorescence, was elucidated from the plasma membrane to the endosome (or lysosome), and finally to the nucleus. The results of this study indicate that plasmid DNA enters into the nucleus not only as a free form but as an associated form complexed with $T_f-liposome$. More interestingly, the $T_f-liposome$ undergoes a nuclear location in the form of ordered structures. This could be a very useful piece of information in designing a safe and advanced gene delivery system.

• Molecules and Cells
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• 제43권4호
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• pp.313-322
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• 2020

Eukaryotes transport biomolecules between intracellular organelles and between cells and the environment via vesicle trafficking. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE proteins) play pivotal roles in vesicle and membrane trafficking. These proteins are categorized as Qa, Qb, Qc, and R SNAREs and form a complex that induces vesicle fusion for targeting of vesicle cargos. As the core components of the SNARE complex, the SNAP25 Qbc SNAREs perform various functions related to cellular homeostasis. The Arabidopsis thaliana SNAP25 homolog AtSNAP33 interacts with Qa and R SNAREs and plays a key role in cytokinesis and in triggering innate immune responses. However, other Arabidopsis SNAP25 homologs, such as AtSNAP29 and AtSNAP30, are not well studied; this includes their localization, interactions, structures, and functions. Here, we discuss three biological functions of plant SNAP25 orthologs in the context of AtSNAP33 and highlight recent findings on SNAP25 orthologs in various plants. We propose future directions for determining the roles of the less well-characterized AtSNAP29 and AtSNAP30 proteins.

• 한국식품과학회지
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• 제45권2호
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• pp.137-141
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• 2013

플라보노이드는 식물의 주요 2차 대사산물 중 하나로 자외선 차단, 식물의 수분을 위한 곤충 유인 등 외부환경에 적응하는데 이로운 역할을 한다. 특히 플라보노이드는 항산화 효과가 우수한 것으로 알려져 노화방지와 생활습관 질병예방에 유용한 건강기능식품소재로 각광받고 있다. 하지만 플라보노이드의 생체이용률은 매우 낮으며 이러한 플라보노이드 흡수과정에 관한 생물학적기전은 최근에 조금씩 밝혀지기 시작하고 있다. 플라보노이드의 수송기전에는 세포 내에서 일어나는 소포체 매개 수송과 세포막 및 소기관 표면 단백질에 의한 막 수송체 매개 수송이 있다. 소포체 매개 수송의 경우 cellular trafficking에 의한 일련의 소포체 유래 vesicle의 융합 반응을 거쳐 식물 세포의 경우 액포 내에 플라보노이드가 축적되거나 세포 외부로 배출된다. 표면 단백질에 의해 플라보노이드의 세포막 흡수가 일어나게 되는데 ATP를 사용한 능동수송, 막 전위를 이용한 2차 수송에 관여하는 다수의 수송체들이 관여하는 것으로 보인다. 다양한 종류의 플라보노이드가 존재하는 만큼 플라보노이드 수송체도 다양하며 어쩌면 모든 플라보노이드의 특이적 수송체를 규명하는 것은 불가능 할 지도 모른다. 하지만 식품에 다량 존재하는 주요 플라보노이드를 모델 화합물로 이용한 연구를 수행하면 이에 관련된 주요 수송체 단백질과 관련 메커니즘에 대해 깊이 이해할 수 있고 이를 통해 생체 이용률을 향상시키는 방법을 생각해 볼 수 있으며 특히 낮은 혈중 농도 조건에서도 조직 세포 내에 플라보노이드 축적을 통해 건강 기능성을 최적화하는 노력을 기울이는데 적절한 과학적 방법을 제시해 줄 수 있을 것으로 기대한다.

• BMB Reports
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• 제53권7호
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• pp.357-366
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• 2020

Currently, most biological research relies on conventional experimental techniques that allow only static analyses at certain time points in vitro or ex vivo. However, if one could visualize cellular dynamics in living organisms, that would provide a unique opportunity to study key biological phenomena in vivo. Intravital microscopy (IVM) encompasses diverse optical systems for direct viewing of objects, including biological structures and individual cells in live animals. With the current development of devices and techniques, IVM addresses important questions in various fields of biological and biomedical sciences. In this mini-review, we provide a general introduction to IVM and examples of recent applications in the field of immunology, oncology, and vascular biology. We also introduce an advanced type of IVM, dubbed real-time IVM, equipped with video-rate resonant scanning. Since the realt-ime IVM can render cellular dynamics with high temporal resolution in vivo, it allows visualization and analysis of rapid biological processes.