• Molecules and Cells
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• 제37권2호
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• pp.89-94
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• 2014

Fission and fusion of mitochondrial tubules are the main processes determining mitochondrial shape and size in cells. As more evidence is found for the involvement of mitochondrial morphology in human pathology, it is important to elucidate the mechanisms of mitochondrial fission and fusion. Mitochondrial morphology is highly sensitive to changing environmental conditions, indicating the involvement of cellular signaling pathways. In addition, the well-established structural connection between the endoplasmic reticulum (ER) and mitochondria has recently been found to play a role in mitochondrial fission. This minireview describes the latest advancements in understanding the regulatory mechanisms controlling mitochondrial morphology, as well as the ER-mediated structural maintenance of mitochondria, with a specific emphasis on mitochondrial fission.

• Molecules and Cells
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• 제41권1호
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• pp.45-49
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• 2018

Autophagy is a lysosome-dependent degradation process that is essential for maintaining cellular homeostasis. In recent years, more studies have focused on the late stages of autophagy. Our group discovered and studied the terminal step of autophagy, namely autophagic lysosome reformation (ALR). ALR is the process that regenerates functional lysosomes from autolysosomes, thus maintaining lysosome homeostasis. ALR involves clathrin-mediated membrane budding from autolysosomes, elongation of membrane tubules along microtubules with the pulling force provided by the motor protein KIF5B, proto-lysosome scission by dynamin 2, and finally maturation of proto-lysosomes to functional lysosomes. In this review, we will summarize progress in unveiling the molecular mechanisms underlying ALR and its potential pathophysiological roles.

• 한국동물학회:학술대회논문집
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• 한국동물학회 2003년도 한국생물과학협회 학술발표대회
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• pp.23-23
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• 2003

No Abstract, See Full Text

• 생명과학회지
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• 제33권11호
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• pp.851-858
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• 2023

Unique cartilage matrix-associated protein (UCMA)은 γ-카르복실화(Gla) 잔기가 풍부한 간외 비타민 K 의존 단백질이다. UCMA는 조골세포 분화를 촉진하고 뼈 형성을 강화한다고 보고되고 있지만 고혈당 스트레스 하에서 조골세포에 미치는 영향에 대해서는 아직 알려진 바가 없다. 본 연구에서는 고혈당 조건하에서의 MC3T3-E1 조골세포에서 UCMA 효과를 조사하기 위해 MC3T3-E1 조골세포를 높은 포도당에 노출한 후 재조합 UCMA 단백질을 처리하였다. MC3T3-E1 세포에서 활성 산소종(ROS)의 생성은 고혈당 조건하에서 증가했으나 UCMA 단백질 처리 후 감소했음을 CellROX 및 MitoSOX 염색으로 확인하였다. 또한 고혈당 조건에서 UCMA 단백질을 함께 처리한 MC3T3-E1 세포에서 정량적 중합효소 연쇄반응 결과, 항산화 유전자인 nuclear factor erythroid 2-related factor 2 와 superoxide dismutase 1 발현이 증가하였다. 동일 조건하에서 UCMA 단백질 처리에 의해 heme oxygenase-1 발현 감소와 함께 세포질에서 핵으로의 전위가 감소되었고, 미토콘드리아 분열에 관여하는 dynamin-related protein 1 발현이 증가하였으며, AKT 신호 활성은 억제되었다. 종합적으로 UCMA는 고혈당에 노출된 조골세포에서 ROS 생성을 완화하고, 항산화 유전자 발현을 증가시키고, 미토콘드리아 역학에 영향을 미치며, AKT 신호를 조절하는 것으로 보인다. 본 연구는 UCMA의 세포 메커니즘에 대한 이해를 돕고, 대사 장애 관련한 골 합병증에 대한 새로운 치료제로서의 잠재적 사용 가능성을 제시하고 있다.

• BMB Reports
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• 제40권3호
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• pp.302-314
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• 2007

N type calcium channels (CaV2.2) play a key role in the gating of transmitter release at presynaptic nerve terminals. These channels are generally regarded as parts of a multimolecular complex that can modulate their open probability and ensure their location near the vesicle docking and fusion sites. However, the proteins that comprise this component remain poorly characterized. We have carried out the first open screen of presynaptic CaV2.2 complex members by an antibody-mediated capture of the channel from purified rat brain synaptosome lysate followed by mass spectroscopy. 589 unique peptides resulted in a high confidence match of 104 total proteins and 40 synaptosome proteome proteins. This screen identified several known CaV2.2 interacting proteins including syntaxin 1, VAMP, protein phosphatase 2A, $G_{o\alpha}$, G$\beta$ and spectrin and also a number of novel proteins, including clathrin, adaptin, dynamin, dynein, NSF and actin. The unexpected proteins were classified within a number of functional classes that include exocytosis, endocytosis, cytoplasmic matrix, modulators, chaperones, and cell-signaling molecules and this list was contrasted to previous reports that catalogue the synaptosome proteome. The failure to detect any postsynaptic density proteins suggests that the channel itself does not exhibit stable trans-synaptic attachments. Our results suggest that the channel is anchored to a cytoplasmic matrix related to the previously described particle web.

• Biomolecules & Therapeutics
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• 제30권5호
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• pp.409-417
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• 2022

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, and accumulating evidence indicates that mitochondrial dysfunction is associated with progressive deterioration in PD patients. Previous studies have shown that sinapic acid has a neuroprotective effect, but its mechanisms of action remain unclear. The neuroprotective effect of sinapic acid was assayed in a PD mouse model generated by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as well as in SH-SY5Y cells. Target protein expression was detected by western blotting. Sinapic acid treatment attenuated the behavioral defects and loss of dopaminergic neurons in the PD models. Sinapic acid also improved mitochondrial function in the PD models. MPTP treatment increased the abundance of mitochondrial fission proteins such as dynamin-related protein 1 (Drp1) and phospho-Drp1 Ser616. In addition, MPTP decreased the expression of the REV-ERB α protein. These changes were attenuated by sinapic acid treatment. We used the pharmacological REV-ERB α inhibitor SR8278 to confirmation of protective effect of sinapic acid. Treatment of SR8278 with sinapic acid reversed the protein expression of phospho-Drp1 Ser616 and REV-ERB α on MPTP-treated mice. Our findings demonstrated that sinapic acid protects against MPTP-induced PD and these effects might be related to the inhibiting abnormal mitochondrial fission through REV-ERB α.

• Tuberculosis and Respiratory Diseases
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• 제81권2호
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• pp.138-147
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• 2018

Background: Recent studies show that mitophagy, the autophagy-dependent turnover of mitochondria, mediates pulmonary epithelial cell death in response to cigarette smoke extract (CSE) exposure and contributes to the development of emphysema in vivo during chronic cigarette smoke (CS) exposure, although the underlying mechanisms remain unclear. Methods: In this study, we investigated the role of mitophagy in the regulation of CSE-exposed lung bronchial epithelial cell (Beas-2B) death. We also investigated the role of a phosphodiesterase 4 inhibitor, roflumilast, in CSE-induced mitophagy-dependent cell death. Results: Our results demonstrated that CSE induces mitophagy in Beas-2B cells through mitochondrial dysfunction and increased the expression levels of the mitophagy regulator protein, PTEN-induced putative kinase-1 (PINK1), and the mitochondrial fission protein, dynamin-1-like protein (DRP1). CSE-induced epithelial cell death was significantly increased in Beas-2B cells exposed to CSE but was decreased by small interfering RNA-dependent knockdown of DRP1. Treatment with roflumilast in Beas-2B cells inhibited CSE-induced mitochondrial dysfunction and mitophagy by inhibiting the expression of phospho-DRP1 and -PINK1. Roflumilast protected against cell death and increased cell viability, as determined by the lactate dehydrogenase release test and the MTT assay, respectively, in Beas-2B cells exposed to CSE. Conclusion: These findings suggest that roflumilast plays a protective role in CS-induced mitophagy-dependent cell death.

• 한국발생생물학회지:발생과생식
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• 제26권2호
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• pp.71-77
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• 2022

In response to luteinizing hormone (LH), a higher concentration of progesterone (P4) is produced in luteal cells of corpus luteum (CL). Mitochondria are an essential cellular organelle in steroidogenesis. The specific engagement of the concept regarding mitochondrial shaping with early stages of steroidogenesis was suggested in reproductive endocrine cells. Although the specific involvement of GTPase dynamin-related protein 1 (Drp1) with steroidogenesis has been demonstrated in luteal cells of bovine CL in vitro, its actual relationship with ovarian steroidogenesis during the estrous cycle remains unknown. In this study, while Fis1 and Opa1 protein levels did not show significant changes during the estrous cycle, Drp1, Mfn1, and Mfn2 proteins exhibited relatively lower levels at proestrus than at estrus or diestrus. 3β-HSD showed higher levels at proestrus than at estrus or diestrus. In addition, Drp1 phosphorylation (s637) was higher in proestrus than in estrus or diestrus. Immune-positive cells for Drp1, pDrp1 (s637), and 3β-HSD were all localized in the cytoplasm of luteal cells in the CL. The immune-positive cells for 3β-HSD were more frequently seen in the CL at proestrus than at estrus or diestrus. Immunoreactivity for Drp1 in luteal cells at proestrus was weaker than that at estrus or diestrus. However, pDrp1 (s637) immune-positive cells were mostly detected in luteal cells at proestrus. These results imply that steroidogenesis (P4 production) in the CL is closely related to phosphorylation of Drp1 at serine 637. Taken together, this study presents evidence that Drp1 phosphorylation at serine 637 is an important step in steroidogenesis in the CL.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2004년도 International Meeting of the Microbiological Society of Korea
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• pp.141-146
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• 2004

SPIN90 was identified to farm molecular complex with $\betaPIX$, WASP and Nck. This complex shows that SPIN90 interacts with Nck in a manner dependent upon cell adhesion to extracellular matrix, but $SPIN90{\cdot}{\beta}PIX{\cdot}WASP$ complex was stable even in suspended cells. This suggests that SPIN90 serves as an adaptor molecule to recruit other proteins to Nck at focal adhesions. SPIN90 was phosphorylated by ERK1, which was, itself, activated by cell adhesion and platelet-derived growth factor. Such phosphorylation of SPIN90 likely promotes the interaction of the $SPIN90{\cdot}{\beta}PIX{\cdot}WASP$ complex and Nck. It thus appears that the interaction of the $SPIN90{\cdot}{\beta}PIX{\cdot}WASP$ complex with Nck is crucial for stable cell adhesion and can be dynamically modulated by SPIN90 phosphorylation that is dependent on cell adhesion and ERX activation. SPIN90 directly binds syndapin I, syndapin isoform II-1 and II-s via its PRD region in vitro, in vivo and also associates with endocytosis core components such as clathrin and dynamin. In neuron and fibroblast, SPIN90 colocalizes with syndapins as puntate form, consistent with a role for SPIN90 in clathrin-mediated endocytosis pathway. Overexpression of SPIN90 N-term inhibits receptor-mediated endocytosis. Interestingly, SPIN90 PRD, binding interface of syndapin, significantly blocks internalization of transferrin, demonstrating SPIN90 involvement in endocytosis in vivo by interacting syndapin. Depletion of endogenous SPIN90 by introducing $\alpha-SPIN90$ also blocks receptor-mediated endocytosis. Actin polymerization could generate farce facilitating the pinch-out event in endocytosis, detach newly formed endocytic vesicle from the plasma membrane or push out them via the cytosol on actin tails. Here we found that SPIN90 localizes to high actin turn over cortical area, actin-membrane interface and membrane ruffle in PDGF treated cells. Overexpression of SPIN90 has an effect on cortical actin rearrangement as filopodia induction and it is mediated by the Arp2/3 complex at cell periphery. Consistent with a role in actin organization, CFP-SPIN90 present in actin comet tail generated by PIP5 $kinase\gamma$ overexpression. Therefore this study suggests that SPIN90 is functional linker between endocytosis and actin cytoskeleton.

• Molecules and Cells
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• 제42권12호
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• pp.893-905
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• 2019

Mitochondria are highly dynamic organelles that constantly undergo fission and fusion processes that closely related to their function. Disruption of mitochondrial dynamics has been demonstrated in acute kidney injury (AKI), which could eventually result in cell injury and death. Previously, we reported that augmenter of liver regeneration (ALR) alleviates renal tubular epithelial cell injury. Here, we gained further insights into whether the renoprotective roles of ALR are associated with mitochondrial dynamics. Changes in mitochondrial dynamics were examined in experimental models of renal ischemia-reperfusion (IR). In a model of hypoxia-reoxygenation (HR) injury in vitro, dynamin-related protein 1 (Drp1) and mitochondrial fission process protein 1 (MTFP1), two key proteins of mitochondrial fission, were downregulated in the Lv-ALR + HR group. ALR overexpression additionally had an impact on phosphorylation of Drp1 Ser637 during AKI. The inner membrane fusion protein, Optic Atrophy 1 (OPA1), was significantly increased whereas levels of outer membrane fusion proteins Mitofusin-1 and -2 (Mfn1, Mfn2) were not affected in the Lv-ALR + HR group, compared with the control group. Furthermore, the mTOR/4E-BP1 signaling pathway was highly activated in the Lv-ALR + HR group. ALR overexpression led to suppression of HR-induced apoptosis. Our collective findings indicate that ALR gene transfection alleviates mitochondrial injury, possibly through inhibiting fission and promoting fusion of the mitochondrial inner membrane, both of which contribute to reduction of HK-2 cell apoptosis. Additionally, fission processes are potentially mediated by promoting tubular cell survival through activating the mTOR/4E-BP1 signaling pathway.