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Hiroaki Takayama

Publications and source records attributed to Hiroaki Takayama.

At least 19 recordsLinked to original sources
PubMed2025

The SELENOP Polymorphism rs7579 Predicts Hepatic Steatosis in Females With Insulin Resistance in the General Population.

CONTEXT: Selenoprotein P is a hepatokine associated with several metabolic processes. Rs7579 (C > T) is a SeP-related functional single nucleotide polymorphism. OBJECTIVE: In this study, we aimed to identify the environmental factors affecting the relationship between rs7579 and metabolic diseases, such as metabolic dysfunction-associated steatotic liver disease, in the general population. METHODS: This cross-sectional study was based on the Shika Study, a survey of residents in the Noto Peninsula of Ishikawa Prefecture. We analyzed a total of 900 adults, measuring full-length selenoprotein P (FL-SeP) serum levels using a sol-particle homogeneous immunoassay. RESULTS: We observed that selenium and FL-SeP serum levels were associated with dyslipidemia. In males, serum selenium was associated with dyslipidemia and hepatic steatosis. However, in females, FL-SeP tended to be associated with diabetes. Participants carrying the TT genotype and hepatic steatosis exhibited higher levels of liver enzymes, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR), and the homeostasis model assessment of β-cell function than those without hepatic steatosis or with other genotypes. In females carrying the TT genotype of rs7579, hepatic steatosis, hypertension, diabetes, obesity, and metabolic syndrome were associated with higher HOMA-IR levels. CONCLUSION: In this study, we revealed that the association between metabolic diseases and HOMA-IR differed single nucleotide polymorphism genotype and sex dependently. In females carrying the TT genotype of rs7579, hepatic steatosis-associated metabolic disorders (diabetes, hypertension, obesity, and metabolic syndrome) were associated with higher HOMA-IR. The results of this study open the way to genetic signatures-based personalized preventive medicines.

CCDC152↗
PubMed2006

Synthesis and biological evaluation of several structural analogs of 2-arachidonoylglycerol, an endogenous cannabinoid receptor ligand.

2-Arachidonoylglycerol (2-AG (1)) is an endogenous ligand for the cannabinoid receptors (CB1 and CB2). There is growing evidence that 2-arachidonoylglycerol plays important physiological and pathophysiological roles in various mammalian tissues and cells, though the details remain to be clarified. In this study, we synthesized several remarkable analogs of 2-arachidonoylglycerol, closely related in chemical structure to 2-arachidonoylglycerol: an analog containing an isomer of arachidonic acid with migrated olefins (2-AGA118 (3)), an analog containing a one-carbon shortened fatty acyl moiety (2-AGA113 (4)), an analog containing an one-carbon elongated fatty acyl moiety (2-AGA114 (5)), a hydroxy group-containing analog (2-AGA105 (6)), a ketone group-containing analog (2-AGA109 (7)), and a methylene-linked analog (2-AGA104 (8)). We evaluated their biological activities as cannabinoid receptor agonists using NG108-15 cells which express the CB1 receptor and HL-60 cells which express the CB2 receptor. Notably, these structural analogs of 2-arachidonoylglycerol exhibited only weak agonistic activities toward either the CB1 receptor or the CB2 receptor, which is in good contrast to 2-arachidonoylglycerol which acted as a full agonist at these cannabinoid receptors. These results clearly indicate that the structure of 2-arachidonoylglycerol is strictly recognized by the cannabinoid receptors (CB1 and CB2) and provide further evidence that the cannabinoid receptors are primarily the intrinsic receptors for 2-arachidonoylglycerol.

Arachidonic Acids↗
PubMed2006

Probing a water channel near the A-ring of receptor-bound 1 alpha,25-dihydroxyvitamin D3 with selected 2 alpha-substituted analogues.

The crystal structure of the vitamin D receptor (VDR) in complex with 1 alpha,25(OH)2D3 revealed the presence of several water molecules near the A-ring linking the ligand C-2 position to the protein surface. Here, we report the crystal structures of the human VDR ligand binding domain bound to selected C-2 alpha substituted analogues, namely, methyl, propyl, propoxy, hydroxypropyl, and hydroxypropoxy. These specific replacements do not modify the structure of the protein or the ligand, but with the exception of the methyl substituent, all analogues affect the presence and/or the location of the above water molecules. The integrity of the channel interactions and specific C-2 alpha analogue directed additional interactions correlate with the binding affinity of the ligands. In contrast, the resulting loss or gain of H-bonds does not reflect the magnitude of HL60 cell differentiation. Our overall findings highlight a rational approach to the design of more potent ligands by building in features revealed in the crystal structures.

Binding Sites↗
PubMed2006

Biological activities of 2alpha-substituted analogues of 1alpha,25-dihydroxyvitamin D3 in transcriptional regulation and human promyelocytic leukemia (HL-60) cell proliferation and differentiation.

Biological activities of 2alpha-substituted 1alpha,25-dihydroxyvitamin D3 analogues were evaluated in vitro. Their binding affinity was examined with calf thymus cytosolic vitamin D receptor (VDR) and rat plasma vitamin D-binding protein (DBP). In addition, the transcriptional activity of the analogues was measured using a rat 25-hydroxyvitamin D3-24-hydroxylase gene promoter, a human osteocalcin gene promoter, and VDR-GAL4 system. This study investigated the biological activities of 2alpha-substituted analogues in comparison with 2beta-substitued analogues at the molecular level, with regard to the structural differences of alkyl, hydroxyalkyl, hydroxyalkoxy substituents at the 2-position of 1alpha,25-dihydroxyvitamin D3.

Animals↗
PubMed2005

The antagonism between 2-methyl-1,25-dihydroxyvitamin D3 and 2-methyl-20-epi-1,25-dihydroxyvitamin D3 in non-genomic pathway-mediated biological responses induced by 1alpha,25-dihydroxyvitamin D3 assessed by NB4 cell differentiation.

We synthesized all eight possible A-ring diastereomers of 2-methyl substituted analogs of 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] and also all eight A-ring diastereomers of 2-methyl-20-epi-1alpha,25(OH)2D3. Their biological activities, especially the antagonistic effect on non-genomic pathway-mediated responses induced by 1alpha,25(OH)2D3 or its 6-s-cis-conformer analog, 1alpha,25(OH)2-lumisterol3, were assessed using an NB4 cell differentiation system. Antagonistic activity was observed for the 1beta-hydroxyl diastereomers, including 2beta-methyl-1beta,25(OH)2D3 and 2beta-methyl-3-epi-1beta,25(OH)2D3. Very interestingly, 2beta-methyl-3-epi-1alpha,25(OH)2D3 also antagonized the non-genomic pathway, despite its 1alpha-hydroxyl group. Other 1alpha-hydroxyl diastereomers did not show antagonistic activity. 20-epimerization diminished the antagonistic effect of all of these analogs on the non-genomic pathway. These findings suggested that the combination of the 2-methyl substitution of the A-ring and 20-epimerization of the side chain could alter the biological activities in terms of antagonism of non-genomic pathway-mediated biological response. Based on a previous report, 2-methyl substitution alters the equilibrium of the A-ring conformation between the alpha- and beta-chair conformers. The 2beta-methyl diastereomers, which exhibited antagonism on non-genomic pathway-mediated response, were considered to prefer the beta-conformer. Further examination to elucidate the relationship between the altered ligand shape and receptors interaction will be important for molecular level understanding of the mechanism of antagonism of the non-genomic pathway.

Calcitriol↗
PubMed2005

Metabolism of 2 alpha-propoxy-1 alpha,25-dihydroxyvitamin D3 and 2 alpha-(3-hydroxypropoxy)-1 alpha,25-dihydroxyvitamin D3 by human CYP27A1 and CYP24A1.

Recently, we demonstrated that some A-ring-modified vitamin D3 analogs had unique biological activity. Of these analogs, 2alpha-propoxy-1alpha,25(OH)2D3 (C3O1) and 2alpha-(3-hydroxypropoxy)-1alpha,25(OH)2D3 (O2C3) were examined for metabolism by CYP27A1 and CYP24A1. Surprisingly, CYP27A1 catalyzed the conversion from C3O1 to O2C3, which has 3 times more affinity for vitamin D receptor than C3O1. Thus, the conversion from C3O1 to O2C3 by CYP27A1 is considered to be a metabolic activation process. Five metabolites were detected in the metabolism of C3O1 and O2C3 by human CYP24A1 including both C-23 and C-24 oxidation pathways. On the other hand, three metabolites of the C-24 oxidation pathway were detected in their metabolism by rat CYP24A1, indicating a species-based difference in the CYP24A1-dependent metabolism of C3O1 and O2C3 between humans and rats. Kinetic analysis revealed that the Km and kcat values of human CYP24A1 for O2C3 are, respectively, approximately 16 times more and 3 times less than those for 1alpha,25(OH)2D3. Thus, the catalytic efficiency, kcat/Km, of human CYP24A1 for O2C3 is only 2% of 1alpha,25(OH)2D3. These results and a high calcium effect of C3O1 and O2C3 in animal experiments using rats suggest that C3O1 and O2C3 are promising for clinical treatment of osteoporosis.

Animals↗
PubMed2004

Design and efficient synthesis of 2 alpha-(omega-hydroxyalkoxy)-1 alpha,25-dihydroxyvitamin D3 Analogues, including 2-epi-ED-71 and their 20-epimers with HL-60 cell differentiation activity.

A concise and efficient synthetic approach to 2 alpha-(omega-hydroxyalkoxy)-1 alpha,25-dihydroxyvitamin D(3) (4a-c), including 2-epi-ED-71, was developed starting from D-glucose as a chiral template for the construction of the 2 alpha-modified A-ring precursors (11a-c). It was found that the best ligand for the bovine thymus vitamin D receptor (VDR) in this series is 4b, which has 1.8 times greater binding affinity for the bovine thymus VDR than that of the natural hormone 1. Interestingly, potency in the induction of HL-60 cell differentiation for 4a-c was almost the same or weaker than that of 1 despite the strong binding affinity for the VDR. Next, we were interested in the "double modification"of 1 based on 4a-c with C20-epimerization, affording 2 alpha-(omega-hydroxyalkoxy)-20-epi-1 alpha,25-dihydroxyvitamin D(3) (20-epi-4a-c). All three 2 alpha-substituted 20-epi analogues of 1 (20-epi-4a-c) exhibited stronger binding affinities for the VDR, and their conformations in the ligand binding domain of VDR were analyzed by molecular modeling. Double-modified analogues of 20-epi-4a-c showed marked HL-60 cell differentiation activity, and 20-epi-4a possesses an activity 58-fold higher than that of the natural hormone 1.

Animals↗
PubMed2004

Metabolism of A-ring diastereomers of 1alpha,25-dihydroxyvitamin D3 by CYP24A1.

The metabolism of 1alpha,25(OH)(2)D(3) (1alpha,3beta) and its A-ring diastereomers, 1beta,25(OH)(2)D(3) (1beta,3beta), 1alpha,25(OH)(2)-3-epi-D(3) (1alpha,3alpha), and 1beta,25(OH)(2)-3-epi-D(3) (1beta,3alpha), was examined to compare the substrate specificity and reaction specificity of CYP24A1 between humans and rats. The ratio between C-23 and C-24 oxidation pathways in human CYP24A1-dependent metabolism of (1alpha,3alpha) and (1beta,3alpha) was 1:1, although the ratio for (1alpha,3beta) and (1beta,3beta) was 1:4. These results indicate that the orientation of the hydroxyl group at the C-3 position determines the ratio between C-23 and C-24 oxidation pathways. A remarkable increase of metabolites in the C-23 oxidation pathway was also observed in rat CYP24A1-dependent metabolism. The binding affinity of human CYP24A1 for A-ring diastereomers was (1alpha,3beta)>(1alpha,3alpha)>(1beta,3beta)>(1beta,3alpha), indicating that both hydroxyl groups at C-1 and C-3 positions significantly affect substrate-binding. The information obtained in this study is quite useful for understanding substrate recognition of CYP24A1 and designing new vitamin D analogs.

Animals↗
PubMed2004

2,2-Functionalized analogues of 1alpha,25-dihydroxyvitamin D3, the potent inducers of cell differentiation.

All four possible A-ring stereoisomers of 2,2-dimethyl-1,25-dihydroxyvitamin D(3) (4) were designed and convergently synthesized. Nine-step conversion of methyl hydroxypivalate 6 provided the desired A-ring enyne synthon (13a,b) in good overall yield. Cross-coupling reaction of the A-ring synthon 13a,b with the CD-ring portion in the presence of palladium catalyst, followed by deprotection, gave the vitamin analogues (4a-d). We also synthesized four stereoisomers of 2,2-ethano-1,25-dihydroxyvitamin D(3) (5), as novel spiro-ring analogues having cyclopropane fused at the C2 position. Biological potencies of the synthesized compounds were assessed in terms of the vitamin D receptor (VDR) binding affinity, as well as the HL-60 cell differentiation-inducing activity. The 2,2-ethano analogue 5a showed a comparable activity to the natural hormone 1, while the 2,2-dimethyl analogue 4a exhibited one-third of the activity of 1 in cell differentiation, with the reduced VDR binding affinity.

Calcitriol↗
PubMed2003

Dramatic enhancement of antagonistic activity on vitamin D receptor: a double functionalization of 1alpha-hydroxyvitamin D3 26,23-lactones.

The synthesis of novel vitamin D receptor antagonists, 24-methyl-1alpha-hydroxyvitamin D(3) 26,23-lactones, is reported. We found that the biological activities of the vitamin D(3) lactones were affected by the structure of the lactone part. Furthermore, introduction of a 2alpha-methyl group into the 24-methylvitamin D(3) lactones dramatically enhanced their anti-vitamin D activity. [reaction: see text]

Calcitriol↗
PubMed2003

Remarkable effect of 2[small alpha]-modification on the VDR antagonistic activity of 1small alpha-hydroxyvitamin D3-26,23-lactones.

Novel 2[small alpha]-methyl-, 2[small alpha]-(3-hydroxypropyl)- and 2[small alpha]-(3-hydroxypropoxy)-substituted 25-dehydro-1[small alpha]-hydroxyvitamin D-26,23-lactone derivatives were efficiently synthesized Reformatsky type allylation and palladium-catalyzed alkenylative cyclization processes, and their biological activities were evaluated. Introducing functional groups into the 2[small alpha]-position of the vitamin D-26,23-lactones resulted in remarkable enhancement of their antagonistic activity on vitamin D receptor (VDR).

Animals↗
PubMed2003

Concise synthesis and biological activities of 2alpha-alkyl- and 2alpha-(omega-hydroxyalkyl)-20-epi-1alpha,25-dihydroxyvitamin D3.

We found a concise route to the Trost A-ring precursor enyne for synthesizing 2alpha-alkylated 1alpha,25-dihydroxyvitamin D(3) (1) from D-glucose. The enynes were coupled with the 20-epi-CD ring part to study the effect of the double modification of 2alpha-substitution and 20-epimerization upon biological activities of 1. The novel three analogues of 2alpha-alkyl- and four analogues of 2alpha-(omega-hydroxyalkyl)-20-epi-1alpha,25-dihydroxyvitamin D(3) (5b-d and 6a-d) showed higher binding affinity for vitamin D receptor (VDR) and more potent activity in induction of HL-60 cell differentiation than those of the natural hormone 1.

Calcitriol↗
PubMed2003

Metabolism of 20-epimer of 1alpha,25-dihydroxyvitamin D3 by CYP24: species-based difference between humans and rats.

The 20-epi form of 1alpha,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)-20-epi-D(3)) is expected as drugs for leukemia, other cancers or psoriasis, because it shows several-hundred fold enhanced ability to induce cell differentiation and growth inhibition than 1alpha,25-dihydroxyvitamin D(3) while its calcemic activity is only slightly elevated. In this study, we compared the human and rat CYP24-dependent metabolism of 1alpha,25(OH)(2)-20-epi-D(3) by using the Escherichia coli expression system. The HPLC and LC-MS analyses of the metabolites revealed that rat CYP24 converted 1alpha,25(OH)(2)-20-epi-D(3) to 25,26,27-trinor-1alpha(OH)-24(COOH)-20-epi-D(3) through 1alpha,24,25(OH)(3)-20-epi-D(3) and 1alpha,25(OH)(2)-24-oxo-20-epi-D(3). The binding affinity of trinor-1alpha(OH)-24(COOH)-20-epi-D(3) for vitamin D receptor (VDR) was less than 1/4000 of that of 1alpha,25(OH)(2)-20-epi-D(3). These results suggest that rat CYP24 can almost completely inactivate 1alpha,25(OH)(2)-20-epi-D(3). On the other hand, human CYP24 mainly converted 1alpha,25(OH)(2)-20-epi-D(3) to its putative demethylated compound with a hydroxyl group, via 1alpha,24,25(OH)(3)-20-epi-D(3), 1alpha,25(OH)(2)-24-oxo-20-epi-D(3), and 1alpha,23,25(OH)(3)-24-oxo-20-epi-D(3). All of these metabolites showed considerable affinity for vitamin D receptor. These results clearly demonstrate the species-based difference between human and rat on the CYP24-dependent metabolism of 1alpha,25(OH)(2)-20-epi-D(3).

Animals↗
PubMed2003

Efficient synthesis of 2-modified 1alpha,25-dihydroxy-19-norvitamin D3 with Julia olefination: high potency in induction of differentiation on HL-60 cells.

Six novel 2-substituted analogues of 1alpha,25-dihydroxy-19-norvitamin D(3), 6a,b-8a,b, were efficiently synthesized utilizing (-)-quinic acid as the A-ring precursor. The C2-modified A-rings were prepared as 4-alkylated (3R,5R)-3,5-dihydroxycyclohexanones 12-15 from (-)-quinic acid based on radical allylation at the C4 position of methyl (-)-quinicate. The new type of the CD-ring coupling partner 23 was synthesized from 25-hydroxy Grundmann's ketone 19 to apply to the modified Julia olefination to construct a diene unit between the A-ring and the CD-ring. The coupling yields, including a deprotection step, were 47-62%. After the separation of the diastereomers based on C2 stereochemistry, the structure (2alpha or 2beta) was determined by (1)H NMR experiments and compared to DeLuca's 2-methyl- and 2-ethyl-1alpha,25-dihydroxy-19-norvitamin D(3). Thus, the synthesized 2alpha-(3-hydroxypropyl)-1alpha,25-dihydroxy-19-norvitamin D(3) (8a) showed almost the same potency in binding to the bovine thymus vitamin D receptor (VDR) as the natural hormone 1, while its beta-isomer 8b had only a 3% affinity. Both 2alpha-allyl- and 2alpha-propyl-1alpha,25-dihydroxy-19-norvitamin D(3) (6a and 7a) and their 2beta-analogues (6b and 7b) possessed a weak affinity for the VDR. The strong VDR ligand 8a was ca. 36-fold more potent in induction of HL-60 cell differentiation than 1, and interestingly, even the weaker ligand 8b showed a 6.7-fold higher potency in the cell differentiation activity than that of 1.

Animals↗
PubMed2003

Aggregation of RecA-derived peptides on single-stranded oligonucleotides triggered by schiff base-mediated crosslinking.

We here show that single-stranded oligonucleotides containing 5-formyl-2'-deoxyuridine (fdU) can crosslink the peptides derived from the DNA binding site of RecA protein through a Schiff base formation. The ability of crosslinking of fdU-containing oligonucleotides was investigated using a series of peptides whose amino acid residues spanning the center of the RecA-derived peptide were sequentially replaced with lysine. Circular dichroism (CD) spectroscopy, gel mobility shift assay and sedimentation experiment demonstrated that crosslinking reaction proceeded efficiently only when the peptides bound to the oligonucleotides.

Amino Acid Sequence↗
PubMed2003

Design and synthesis of potent vitamin D receptor antagonists with A-ring modifications: remarkable effects of 2alpha-methyl introduction on antagonistic activity.

Novel A-ring analogues of the vitamin D receptor (VDR) antagonist (3a), ZK-159222, and its 24-epimer (3b) were convergently synthesized. Preparation of the CD-ring portions with the side chains of 3a,b, followed by palladium-catalyzed cross-coupling with the A-ring enyne precursors (15a,b), (3S,4S,5R)- and (3S,4S,5S)-bis[(tert-butyldimethylsilyl)oxy]-4-methyloct-1-en-7-yne, afforded the 2alpha-methyl-introduced analogues (4a,b) and their 3-epimers (5a,b). The biological profiles of the hybrid analogues were assessed in terms of affinity for VDR, and antagonistic activity to inhibit HL-60 cell differentiation induced by the natural hormone, 1alpha,25-dihydroxyvitamin D(3). The analogue 4a showed an approximately fivefold higher antagonistic activity compared with 3a. The 2alpha-methyl introduction into 3a increased the receptor affinity, thereby enhancing VDR antagonism. This approach to design potent antagonists based on hybridization of structural motifs in the A-ring and in the side chain may prove to be valuable.

Animals↗
PubMed2003

Design, synthesis, and biological studies of the A-ring-modified 1,25-dihydroxyvitamin D3 analogs.

Antitumor effects of 1alpha,25-dihydroxyvitamin D3 analogs have recently become one of the major topics of the vitamin D research field. We focused on the structure-activity relationships of the A-ring moiety of the vitamin D molecule and found several strong agonists of the vitamin D receptor, using a design of introducing a functional group into the C2 position. In the first step, all eight possible diastereomers of novel 2-methyl-1,25-dihydroxyvitamin D3 were synthesized using the convergent method with palladium catalyzed coupling reaction. We studied conformational analysis of each isomer based on 1H NMR and computer calculations; and biologically, VDR binding affinity, potency of induction of HL-60 cell differentiation, and apoptosis were investigated in detail. The biological effect of double modification in a combination of the CD-ring side chain (20-epi, 20-epi-22R-methyl, and KH-1060 types) and the 2-methyl group was then evaluated. In this context, 5,6-trans derivatives of 2-methyl analogs were also synthesized and tested. Through these experiments, our accumulated knowledge that the 2a-methylated analog with the natural la,3fl-dihydroxyl groups possesses a strong and unique biological profile guided us the next synthetic goal, i.e., three kinds of longer functional groups: 2alpha-alkyl, 2alpha-hydroxyalkyl, and 2alpha-hydroxyalkoxyl groups, which were introduced into 1alpha,25-dihydroxyvitamin D3, stereoselectively. We found that five of our new 2alpha-modified analogs show higher VDR-binding affinity than that of the natural hormone. HL-60 cell differentiation induction activities and calcium mobilization were studied for some of these compounds. These are the first examples, including the pioneer 2a-methyl analog, that exhibit higher VDR-binding affinity than 1alpha,25-dihydroxyvitamin D3 with pure A-ring modifications. To explain the effect, docking studies of the synthetic ligands to VDR are also described. This study could stimulate the development of antitumor medicines of the vitamin D analogs.

Cell Differentiation↗