Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder worldwide, causing dementia and affecting millions of individuals. One prominent characteristic in the brains of AD patients is glucose hypometabolism. In the context of galactose metabolism, intracellular glucose levels are heightened. Galactose mutarotase (GALM) plays a crucial role in maintaining normal galactose metabolism by catalyzing the conversion of β-D-galactose into α-D-galactose (α-D-G). The latter is then converted into glucose-6-phosphate, improving glucose metabolism levels. However, the involvement of GALM in AD progression is still unclear. In the present study, we found that the expression of GALM was significantly increased in AD patients and model mice. Genetic knockdown of GALM using adeno-associated virus did not change the expression of amyloid precursor protein (APP) and APP-cleaving enzymes including a disintegrin and metalloprotease 10 (ADAM10), β-site APP-cleaving enzyme 1 (BACE1), and presenilin-1 (PS1). Interestingly, genetic overexpression of GALM reduced APP and Aβ deposition by increasing the maturation of ADAM10, although it did not alter the expression of BACE1 and PS1. Further electrophysiological and behavioral experiments showed that GALM overexpression significantly ameliorated the deficits in hippocampal CA1 long-term potentiation (LTP) and spatial learning and memory in AD model mice. Importantly, direct α-D-G (20 mg/kg, i.p.) also inhibited Aβ deposition by increasing the maturation of ADAM10, thereby improving hippocampal CA1 LTP and spatial learning and memory in AD model mice. Taken together, our results indicate that GALM shifts APP processing towards α-cleavage, preventing Aβ generation by increasing the level of mature ADAM10. These findings indicate that GALM may be a potential therapeutic target for AD, and α-D-G has the potential to be used as a dietary supplement for the prevention and treatment of AD.
Animals ; ADAM10 Protein/metabolism* ; Alzheimer Disease/pathology* ; Amyloid Precursor Protein Secretases/metabolism* ; Disease Models, Animal ; Humans ; Mice ; Amyloid beta-Peptides/metabolism* ; Male ; Mice, Transgenic ; Membrane Proteins/metabolism* ; Cognitive Dysfunction/pathology* ; Mice, Inbred C57BL ; Amyloid beta-Protein Precursor/metabolism* ; Female ; Hippocampus/metabolism* ; Long-Term Potentiation/physiology*

OBJECTIVETo investigate the expression of miR-140-5p and ADAM10 in hypopharyngeal carcinoma tissues and their effects on the migration and invasion of FaDu cells and underlying mechanism.

METHODSThe miR-140-5p and ADAM10 mRNA levels in 33 cases of hypopharyngeal carcinoma tissues and adjacent normal tissues were measured by real-time quantitative polymerase chain reaction (RT-qPCR). Transwell migration assay and transwell invasion assay were used to test the metastasis ability of FaDu cells after upregulation or downregulation of miR-140-5p and downregulation of ADAM10. The protein expression levels of ADAM10 in hypopharyngeal carcinoma tissues and the FaDu cells after transfection were determined by Western blot assays.

RESULTSThe expression level of miR-140-5p was significantly downregulated in hypopharyngeal carcinoma tissues compared with adjacent tissues (t=-4.016, P<0.01), which was significantly correlated with tumor classification and lymph node metastasis (P<0.05). Conversely, mRNA and protein expressions of ADAM10 were significantly upregulated in tumor tissues (t=3.960, P<0.01; t=12.089, P<0.01), and were significantly downregulated in the FaDu cells after tranfected with si-ADAM10 (t=8.653, P<0.05; t=5.191, P<0.05). Transwell assay showed that compare with control group, the migration and invasive cells decreased significantly in hsa-mir-140-5p group (t=3.255, P<0.05; t=2.942, P<0.05), while increased significantly in anti-hsa-mir-140-5p group, (t=-13.521, P<0.05; t=-6.223, P<0.05). The migration and invasive cells in si-ADAM10 group were less than those in control group (t=4.759, P<0.05; t=3.663, P<0.05). The downregulation of ADAM10 attenuated the effect of anti-mir-140-5p in FaDu cells. Western blot assay showed that ADAM10 expression was apparently decreased in hsa-mir-140-5p group and increased in anti-mir-140-5p group compared with control group.

CONCLUSIONSThe expression of miR-140-5p was significantly downregulated in hypopharyngeal carcinoma tissues and correlated with tumor classification and lymph node metastasis. ADAM10 was upregulated in tumor tissues. MiR-140-5p suppresses the migration and invasion abilities of FaDu cells, possibly through downregulation of ADAM10.

ADAM Proteins ; metabolism ; ADAM10 Protein ; Amyloid Precursor Protein Secretases ; metabolism ; Cell Line, Tumor ; Cell Movement ; Down-Regulation ; Gene Expression Regulation, Neoplastic ; Humans ; Hypopharyngeal Neoplasms ; pathology ; Lymphatic Metastasis ; Membrane Proteins ; metabolism ; MicroRNAs ; metabolism ; RNA, Messenger ; metabolism ; Transfection

OBJECTIVETo investigate the main proteinases responsible for CD16b shedding under different stimulators.

METHODSHEK293 cell line stably expressing CD16b was constructed by lentivirus system. The cell line was then overexpressed with a disintegrin and metalloproteinase 10 (ADAM10) or ADAM17, suppressed with short hairpin RNA of ADAM10 or ADAM17, and reconstituted with ADAM10 or ADAM17, respectively. After each treatment, the cell line was stimulated with ionomycin or phorbol 12-myristate- 13-acetate (PMA) for 12 hours. The soluble CD16b released from cell membrane was detected by immunoprecipition and immunoblot. Quantitation was then implemented to compare the amount of soluble CD16b in cell supernatant after stimulation.

RESULTSHEK293 cell line stably expressing CD16b was successfully established. When CD16b expressing cell line was overexpressed with ADAM10, shedding of CD16b was increased after stimulation with ionomycin but not PMA; when the cell line overexpressed with ADAM17, shedding of CD16b was increased after stimulation with PMA but not ionomycin. Similarly, when ADAM10 was suppressed by short hairpin RNA, CD16b shedding was decreased after stimulation with ionomycin; when ADAM17 was suppressed by short hairpin RNA, CD16b shedding was decreased after stimulation with PMA. The shedding of CD16b was increased again when CD16b expressing cell line was reconstituted with ADAM10 and stimulated by ionomycin or reconstituted with ADAM17 and stimulated by PMA.

CONCLUSIONSBoth ADAM10 and ADAM17 could shed CD16b, but they possess differed preferences. ADAM10 is the main sheddase under stimulation of ionomycin, while ADAM17 is the main sheddase under stimulation of PMA.

ADAM Proteins ; genetics ; metabolism ; physiology ; ADAM10 Protein ; ADAM17 Protein ; Amyloid Precursor Protein Secretases ; genetics ; metabolism ; physiology ; Calcium Ionophores ; pharmacology ; Carcinogens ; pharmacology ; Cells, Cultured ; Drug Evaluation, Preclinical ; GPI-Linked Proteins ; metabolism ; Gene Knockdown Techniques ; HEK293 Cells ; Humans ; Ionomycin ; pharmacology ; Membrane Proteins ; genetics ; metabolism ; physiology ; Protein Processing, Post-Translational ; drug effects ; Protein Transport ; drug effects ; Proteolysis ; drug effects ; Receptors, IgG ; metabolism ; Tetradecanoylphorbol Acetate ; pharmacology ; Transfection

OBJECTIVETo study the effect of Panax notoginseng saponins (PNS) on expression of alpha-aecretase mRNA in the brains of senescence-accelerated SAMP8 mice.

METHODSAMP8 mice were randomly divided into the control group, the PNS high-dosage group (200 mg x kg(-1)), the PNS low-dosage group (100 mg x kg(-1)) and the huperzine A group (0.3 mg x kg(-1)), with eight mice in each group. The control group and each administration group were orally administered with the same volume of double distilled water once for consecutively two months. The expression of alpha-secretase (ADAM 9, ADAM10, ADAM17) mRNA was assayed by real-time fluorescence quantitative polymerase chain reaction (Real-time PCR).

RESULTThe expression of ADAM9 mRNA in PNS high-dosage group and huperzine A group were significantly higher than that of the control group (P < 0.05). The expression of ADAM10 in the PNS high-dosage group, the PNS low-dosage group and the huperzine A group showed no significant difference from the control group.

CONCLUSIONPNS can up-regulate expressions of ADAM9 mRNA and down-regulate expressions of ADAM10 mRNA in the brains of SAMP8 mice.

ADAM Proteins ; genetics ; ADAM10 Protein ; Alzheimer Disease ; drug therapy ; metabolism ; Amyloid Precursor Protein Secretases ; genetics ; Animals ; Disease Models, Animal ; Gene Expression Regulation, Enzymologic ; drug effects ; Membrane Proteins ; genetics ; Mice ; Panax notoginseng ; RNA, Messenger ; analysis ; Saponins ; pharmacology

The sigma-1 receptor is a molecular chaperone protein highly enriched in the brain. Recent studies linked it to many diseases, such as drug addition, Alzheimer's disease, stroke, depression, and even cancer. Sigma-1 receptor is enriched in lipid rafts, which are membrane microdomains essential in signaling processes. One of those signaling processes is ADAM17- and ADAM10-dependent ectodomain shedding. By using an alkaline phosphatase tagged substrate reporter system, we have shown that ADAM10-dependent BTC shedding was very sensitive to both membrane lipid component change and sigma-1 receptor agonist DHEAS treatment while ADAM17-dependent HB-EGF shedding was not; and overexpression of sigma-1 receptor diminished ADAM17- and ADAM10-dependent shedding. Our results indicate that sigma-1 receptor plays an important role in modifying the function of transmembrane proteases.
ADAM Proteins ; metabolism ; ADAM10 Protein ; ADAM17 Protein ; Amyloid Precursor Protein Secretases ; metabolism ; Animals ; Betacellulin ; COS Cells ; Cercopithecus aethiops ; Gene Expression ; HEK293 Cells ; Heparin-binding EGF-like Growth Factor ; Humans ; Intercellular Signaling Peptides and Proteins ; metabolism ; Membrane Microdomains ; metabolism ; Membrane Proteins ; metabolism ; Receptors, sigma ; agonists ; metabolism