Extracellular deposition of β-amyloid (Aβ) and intracellular hyperphosphorylated tau are the predominant pathological changes in Alzheimer's disease (AD). Increasing evidence demonstrates a critical role of a variety of small GTPases, namely Ras-related proteins (Rabs), in the pathogenesis of AD. As crucial regulators of intracellular membrane trafficking, alteration in Rab protein expression and function represents one of the primary factors contributing to the abnormal membrane trafficking in AD. Additionally, the Rab GTPases are also involved in the development of Aβ, tau and other pathological changes associated with AD. In this article, we conduct a comprehensive review on the primary functions of multiple Rab proteins and their involvement in the pathogenesis of AD.
Humans ; Alzheimer Disease ; rab GTP-Binding Proteins/metabolism* ; Amyloid beta-Peptides/metabolism* ; tau Proteins/metabolism*

OBJECTIVE: To investigate the effect of inhibition of RAB27 protein family, which plays a pivotal role in exosome secretion, on biological behaviors of triple-negative breast cancer cells. METHODS: Quantitative real-time PCR and Western blotting were used to examine the expressions of RAB27 family and exosome secretion in 3 triple-negative breast cancer cell lines (MDA-MB-231, MDA-MB-468, and Hs578T) and a normal breast epithelial cell line (MCF10A). The effect of small interfering RNA (siRNA)-mediated silencing of RAB27a and RAB27b on exosome secretion in the 3 breast cancer cell lines was detected using Western blotting, and the changes in cell proliferation, invasion and adhesion were evaluated. RESULTS: Compared with normal breast epithelial cells, the 3 triple-negative breast cancer cell lines exhibited more active exosome secretion (P < 0.001) and showed significantly higher expressions of RAB27a and RAB27b at both the mRNA and protein levels (P < 0.01). Silencing of RAB27a in the breast cancer cells significantly down-regulated exosome secretion (P < 0.001), while silencing of RAB27b did not significantly affect exosome secretion. The 3 breast cancer cell lines with RAB27a silencing-induced down-regulation of exosome secretion showed obvious inhibition of proliferation, invasion and adhesion (P < 0.01) as compared with the cell lines with RAB27b silencing. CONCLUSION RAB27a plays central role in the exosome secretion in triple-negative breast cancer cells, and inhibiting RAB27a can inhibit the proliferation, invasion and adhesion of the cells.
Humans ; rab GTP-Binding Proteins/metabolism* ; Triple Negative Breast Neoplasms ; Cell Line, Tumor ; rab27 GTP-Binding Proteins/metabolism* ; RNA, Small Interfering/genetics* ; Cell Proliferation/genetics* ; Gene Expression Regulation, Neoplastic

OBJECTIVE: To explore the interaction between Tubulin beta 4B class IVb (TUBB4B) and Agtpbp1/cytosolic carboxypeptidase- like1 (CCP1) in mouse primary spermatocytes (GC-2 cells) and the role of TUBB4B in regulating the development of GC-2 cells. METHODS: Lentiviral vectors were used to infect GC-2 cells to construct TUBB4B knockdown and negative control (NC-KD) cells. The stable cell lines with TUBB4B overexpression (Tubb4b-OE) and the negative control (NC-OE) cells were screened using purinomycin. RT-qPCR and Western blotting were used to verify successful cell modeling and explore the relationship between TUBB4B and CCP1 expressions in GC-2 cells. The effects of TUBB4B silencing and overexpression on the proliferation and cell cycle of GC-2 cells were evaluated using CCK8 assay and flow cytometry. The signaling pathway proteins showing significant changes in response to TUBB4B silencing or overexpression were identified using Western blotting and immunofluorescence assay and then labeled for verification at the cellular level. RESULTS: Both TUBB4B silencing and overexpression in GC-2 cells caused consistent changes in the mRNA and protein expressions of CCP1 (P < 0.05). Similarly, TUBB4B expression also showed consistent changes at the mRNA and protein after CCP1 knockdown and restoration (P < 0.05). TUBB4B knockdown and overexpression had no significant effect on proliferation rate or cell cycle of GC-2 cells, but caused significant changes in the key proteins of the nuclear factor kappa-B (NF-κB) signaling pathway (p65 and p-p65) and the mitogen-activated protein kinase (MAPK) signaling pathway (ErK1/2 and p-Erk1/2) (P < 0.05); CCP1 knockdown induced significant changes in PolyE expression in GC-2 cells (P < 0.05). CONCLUSIONS TUBB4B and CCP1 interact via a mutual positive regulation mechanism in GC-2 cells. CCP-1 can deglutamize TUBB4B, and the latter is involved in the regulation of NF-κB and MAPK signaling pathways in primary spermatocytes.
Animals ; Male ; Mice ; GTP-Binding Proteins/metabolism* ; Mitogen-Activated Protein Kinases/metabolism* ; NF-kappa B/metabolism* ; RNA, Messenger ; Serine-Type D-Ala-D-Ala Carboxypeptidase/metabolism* ; Signal Transduction ; Spermatocytes ; Tubulin/genetics*

Proto-Oncogene Proteins c-akt ; TOR Serine-Threonine Kinases ; GTP-Binding Protein alpha Subunits, Gi-Go/metabolism*

Humans ; Brain Neoplasms/metabolism* ; Cell Line, Tumor ; Cell Proliferation ; Gene Expression Regulation, Neoplastic ; Glioma/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Signal Transduction ; ATPases Associated with Diverse Cellular Activities/metabolism* ; Mitochondrial Proteins/metabolism* ; GTP-Binding Protein alpha Subunits/metabolism*

Tumor-associated macrophages (TAMs) play crucial roles in tumor progression and immune responses. However, mechanisms of driving TAMs to antitumor function remain unknown. Here, transcriptome profiling analysis of human oral cancer tissues indicated that regulator of G protein signaling 12 (RGS12) regulates pathologic processes and immune-related pathways. Mice with RGS12 knockout in macrophages displayed decreased M1 TAMs in oral cancer tissues, and extensive proliferation and invasion of oral cancer cells. RGS12 increased the M1 macrophages with features of increased ciliated cell number and cilia length. Mechanistically, RGS12 associates with and activates MYC binding protein 2 (MYCBP2) to degrade the cilia protein kinesin family member 2A (KIF2A) in TAMs. Our results demonstrate that RGS12 is an essential oral cancer biomarker and regulator for immunosuppressive TAMs activation.
Mice ; Humans ; Animals ; Tumor-Associated Macrophages/metabolism* ; Carcinoma, Squamous Cell ; Squamous Cell Carcinoma of Head and Neck ; Mouth Neoplasms ; GTP-Binding Proteins/metabolism* ; Head and Neck Neoplasms ; Ubiquitin-Protein Ligases/metabolism* ; Adaptor Proteins, Signal Transducing/metabolism* ; RGS Proteins/metabolism* ; Kinesins/metabolism* ; Repressor Proteins/metabolism*

To study the molecular mechanism of salt stress response of peanut small GTP binding protein gene AhRabG3f, a 1 914 bp promoter fragment upstream of the start codon of AhRabG3f gene (3f-P) from peanut was cloned. Subsequently, five truncated fragments (3f-P1-3f-P5) with lengths of 1 729, 1 379, 666, 510 and 179 bp were obtained through deletion at the 5' end, respectively. Plant expression vectors where these six promoter fragments were fused with the gus gene were constructed and transformed into tobacco by Agrobacterium-mediated method, respectively. GUS expression in transgenic tobacco and activity analysis were conducted. The gus gene expression can be detected in the transgenic tobacco harboring each promoter segment, among which the driving activity of the full-length promoter 3f-P was the weakest, while the driving activity of the promoter segment 3f-P3 was the strongest. Upon exposure of the transgenic tobacco to salt stress, the GUS activity driven by 3f-P, 3f-P1, 3f-P2 and 3f-P3 was 3.3, 1.2, 1.9 and 1.2 times compared to that of the transgenic plants without salt treatment. This suggests that the AhRabG3f promoter was salt-inducible and there might be positive regulatory elements between 3f-P and 3f-P3 in response to salt stress. The results of GUS activity driven by promoter fragments after salt treatment showed that elements included MYB and GT1 between 1 930 bp and 1 745 bp. Moreover, a TC-rich repeat between 682 bp and 526 bp might be positive cis-elements responsible for salt stress, and an MYC element between 1 395 bp and 682 bp might be a negative cis-element responsible for salt stress. This study may facilitate using the induced promoter to regulate the salt resistance of peanut.
Arachis/genetics* ; Fabaceae/genetics* ; GTP-Binding Proteins/metabolism* ; Gene Expression Regulation, Plant ; Glucuronidase/metabolism* ; Plant Proteins/metabolism* ; Plants, Genetically Modified/genetics* ; Salt Stress ; Stress, Physiological/genetics* ; Tobacco/genetics*

Objective: To investigate the effects of continuing exercise and load-bearing interval exercise on skeletal muscle tissue cell morphology, Ras-related proteins 5 (Rab5) mRNA and protein expression and glucose metabolism in skeletal muscle of type 2 diabetic mellitus (T2DM) rats. Methods: Eight SD rats were selected as controls group (CR), the others SD rats were fed with high fat and high sugar diet for 6 weeks before injecting STZ (35 mg/kg) to construct the T2DM model. Twenty-four T2DM rats were randomly devided into T2DM model group (DRM), continuing exercise group (DCRE) and load-bearing interval exercise group (DWRE), 8 rats in each group. DCRE exercise protocol, that was 15 m/min (10 min), 20 m/min (40 min), 15 m/min (10 min), during the first 1～2 weeks, and 18 m/min (10 min), 25 m/min (40 min), 15 m/min (10 min), during the second 3～8 weeks. DWRE exercise protocol: load weight 15% / 1～2 weeks, 30% / 3～4 weeks, 45% / 5～8 weeks, with 15 m/min (5 min), 12 groups and 3 min rest between groups. After 8 weeks, pathological and morphological changes of skeletal muscle were observed by HE. Rab5 and Glucose transporte 4 (GLUT4) mRNA expressions of skeletal muscle were tested by qRT-PCR. Rab5 protein expression in skeletal muscle was tested by immunofluorescence histochemistry and Western blot, and plasma Rab5 and Glycosylated Hemoglobin (GHb) concentrations were detected by ELISA. Results: Comparison with CR, DRM showed pathological damage of skeletal muscle, the expressions of Rab5 mRNA, protein and GLUT4 mRNA were all decreased in skeletal muscle (P＜0.01), the serum levels of Rab5 and GHb were both significantly elevated (P＜0.01). Comparison with DRM, both DCRE and DWRE significantly improved pathological damages of skeletal muscle, the expressions of Rab5 mRNA, protein and GLUT4 mRNA were all increased in skeletal muscle (P＜ 0.05, P＜0.01), the serum levels of Rab5 and GHb were decreased (P＜0.05, P＜0.01), and there was no statistical difference between DCRE and DWRE groups (P＞0.05). Conclusion: Two exercise modes can improve the pathological injury of skeletal muscle in type 2 diabetic rats, and enhance GLUT4 transport capacity by improving the expression of Rab5 gene and protein in skeletal muscle, and alleviate the imbalance of glucose metabolism homeostasis in skeletal muscle. However, there was no significant difference between the effects of two exercise modes on Rab5 protein and glucose metabolism in skeletal muscle.
Animals ; Diabetes Mellitus, Experimental/metabolism* ; Diabetes Mellitus, Type 2/metabolism* ; Glucose/metabolism* ; Glycated Hemoglobin ; Insulin ; Muscle, Skeletal/metabolism* ; Physical Conditioning, Animal/methods* ; RNA, Messenger/metabolism* ; Rats ; Rats, Sprague-Dawley ; rab5 GTP-Binding Proteins/metabolism*

Metformin is currently a strong candidate anti-tumor agent in multiple cancers. However, its anti-tumor effectiveness varies among different cancers or subpopulations, potentially due to tumor heterogeneity. It thus remains unclear which hepatocellular carcinoma (HCC) patient subpopulation(s) can benefit from metformin treatment. Here, through a genome-wide CRISPR-Cas9-based knockout screen, we find that DOCK1 levels determine the anti-tumor effects of metformin and that DOCK1 is a synthetic lethal target of metformin in HCC. Mechanistically, metformin promotes DOCK1 phosphorylation, which activates RAC1 to facilitate cell survival, leading to metformin resistance. The DOCK1-selective inhibitor, TBOPP, potentiates anti-tumor activity by metformin in vitro in liver cancer cell lines and patient-derived HCC organoids, and in vivo in xenografted liver cancer cells and immunocompetent mouse liver cancer models. Notably, metformin improves overall survival of HCC patients with low DOCK1 levels but not among patients with high DOCK1 expression. This study shows that metformin effectiveness depends on DOCK1 levels and that combining metformin with DOCK1 inhibition may provide a promising personalized therapeutic strategy for metformin-resistant HCC patients.
Animals ; Antineoplastic Agents/therapeutic use* ; Carcinoma, Hepatocellular/metabolism* ; Cell Line, Tumor ; Clustered Regularly Interspaced Short Palindromic Repeats ; Genome ; Humans ; Liver Neoplasms/metabolism* ; Metformin/therapeutic use* ; Mice ; Phosphorylation ; Synthetic Lethal Mutations ; Transcription Factors/metabolism* ; rac GTP-Binding Proteins/metabolism*

OBJECTIVE: To investigate the effects of Bax inhibitor 1 (BI- 1) and optic atrophy protein 1 (OPA1) on vascular calcification (VC). METHODS: Mouse models of VC were established in ApoE-deficient (ApoE^-/-) diabetic mice by high-fat diet feeding for 12 weeks followed by intraperitoneal injections with N^ε-carboxymethyl-lysine for 16 weeks. ApoE^-/- mice (control group), ApoE^-/- diabetic mice (VC group), ApoE^-/- diabetic mice with BI-1 overexpression (VC + BI-1^TG group), and ApoE^-/- diabetic mice with BI-1 overexpression and OPA1 knockout (VC+BI-1^TG+OPA1^-/- group) were obtained for examination of the degree of aortic calcification using von Kossa staining. The changes in calcium content in the aorta were analyzed using ELISA. The expressions of Runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP-2) were detected using immunohistochemistry, and the expression of cleaved caspase-3 was determined using Western blotting. Cultured mouse aortic smooth muscle cells were treated with 10 mmol/L β-glycerophosphate for 14 days to induce calcification, and the changes in BI-1 and OPA1 protein expressions were examined using Western blotting and cell apoptosis was detected using TUNEL staining. RESULTS: ApoE^-/- mice with VC showed significantly decreased expressions of BI-1 and OPA1 proteins in the aorta (P=0.0044) with obviously increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 (P= 0.0041). Overexpression of BI-1 significantly promoted OPA1 protein expression and reduced calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 (P=0.0006). OPA1 knockdown significantly increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 in the aorta (P=0.0007). CONCLUSION BI-1 inhibits VC possibly by promoting the expression of OPA1, reducing calcium deposition and inhibiting osteogenic differentiation and apoptosis of the vascular smooth muscle cells.
Animals ; Apolipoproteins E/metabolism* ; Calcium/metabolism* ; Caspase 3/metabolism* ; Cells, Cultured ; Core Binding Factor Alpha 1 Subunit/metabolism* ; Diabetes Mellitus, Experimental/pathology* ; GTP Phosphohydrolases/metabolism* ; Membrane Proteins/metabolism* ; Mice ; Mice, Knockout ; Muscle, Smooth, Vascular/pathology* ; Myocytes, Smooth Muscle/pathology* ; Optic Atrophy, Autosomal Dominant/pathology* ; Osteogenesis ; Vascular Calcification/pathology* ; bcl-2-Associated X Protein/metabolism*