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Tsai WC, Aleem AM, Whittington C, Cortopassi WA, Kalyanaraman C, Baroz A, Iavarone AT, Skrzypczak-Jankun E, Jacobson MP, Offenbacher AR, Holman T. Mutagenesis, Hydrogen-Deuterium Exchange, and Molecular Docking Investigations Establish the Dimeric Interface of Human Platelet-Type 12-Lipoxygenase. Biochemistry 2021; 60:802-812. [PMID: 33635645 DOI: 10.1021/acs.biochem.1c00053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
It was previously shown that human platelet 12S-lipoxygenase (h12-LOX) exists as a dimer; however, the specific structure is unknown. In this study, we create a model of the dimer through a combination of computational methods, experimental mutagenesis, and hydrogen-deuterium exchange (HDX) investigations. Initially, Leu183 and Leu187 were replaced by negatively charged glutamate residues and neighboring aromatic residues were replaced with alanine residues (F174A/W176A/L183E/L187E/Y191A). This quintuple mutant disrupted both the hydrophobic and π-π interactions, generating an h12-LOX monomer. To refine the determinants for dimer formation further, the L183E/L187E mutant was generated and the equilibrium shifted mostly toward the monomer. We then submitted the predicted monomeric structure to protein-protein docking to create a model of the dimeric complex. A total of nine of the top 10 most energetically favorable docking conformations predict a TOP-to-TOP dimeric arrangement of h12-LOX, with the α-helices containing a Leu-rich region (L172, L183, L187, and L194), corroborating our experimental results showing the importance of these hydrophobic interactions for dimerization. This model was supported by HDX investigations that demonstrated the stabilization of four, non-overlapping peptides within helix α2 of the TOP subdomain for wt-h12-LOX, consistent with the dimer interface. Most importantly, our data reveal that the dimer and monomer of h12-LOX have distinct biochemical properties, suggesting that the structural changes due to dimerization have allosteric effects on active site catalysis and inhibitor binding.
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Affiliation(s)
- Wan-Chen Tsai
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Ansari Mukhtar Aleem
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Chris Whittington
- Department of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
| | - Wilian A Cortopassi
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco, San Francisco, California 94143, United States
| | - Chakrapani Kalyanaraman
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco, San Francisco, California 94143, United States
| | - Angel Baroz
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Anthony T Iavarone
- QB3/Chemistry Mass Spectrometry Facility, University of California, Berkeley, Berkeley, California 94720, United States
| | - Ewa Skrzypczak-Jankun
- Department of Urology, University of Toledo, Health Science Campus, Toledo, Ohio 43614, United States
| | - Matthew P Jacobson
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco, San Francisco, California 94143, United States
| | - Adam R Offenbacher
- Department of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
| | - Theodore Holman
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
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Hernandez-Perez M, Kulkarni A, Samala N, Sorrell C, El K, Haider I, Aleem AM, Holman TR, Rai G, Tersey SA, Mirmira RG, Anderson RM. A 12-lipoxygenase-Gpr31 signaling axis is required for pancreatic organogenesis in the zebrafish. FASEB J 2020; 34:14850-14862. [PMID: 32918516 PMCID: PMC7606739 DOI: 10.1096/fj.201902308rr] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 08/21/2020] [Accepted: 08/25/2020] [Indexed: 12/19/2022]
Abstract
12-Lipoxygenase (12-LOX) is a key enzyme in arachidonic acid metabolism, and alongside its major product, 12-HETE, plays a key role in promoting inflammatory signaling during diabetes pathogenesis. Although 12-LOX is a proposed therapeutic target to protect pancreatic islets in the setting of diabetes, little is known about the consequences of blocking its enzymatic activity during embryonic development. Here, we have leveraged the strengths of the zebrafish-genetic manipulation and pharmacologic inhibition-to interrogate the role of 12-LOX in pancreatic development. Lipidomics analysis during zebrafish development demonstrated that 12-LOX-generated metabolites of arachidonic acid increase sharply during organogenesis stages, and that this increase is blocked by morpholino-directed depletion of 12-LOX. Furthermore, we found that either depletion or inhibition of 12-LOX impairs both exocrine pancreas growth and unexpectedly, the generation of insulin-producing β cells. We demonstrate that morpholino-mediated knockdown of GPR31, a purported G-protein-coupled receptor for 12-HETE, largely phenocopies both the depletion and the inhibition of 12-LOX. Moreover, we show that loss of GPR31 impairs pancreatic bud fusion and pancreatic duct morphogenesis. Together, these data provide new insight into the requirement of 12-LOX in pancreatic organogenesis and islet formation, and additionally provide evidence that its effects are mediated via a signaling axis that includes the 12-HETE receptor GPR31.
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Affiliation(s)
- Marimar Hernandez-Perez
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Abhishek Kulkarni
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Niharika Samala
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Cody Sorrell
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kimberly El
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Isra Haider
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ansari Mukhtar Aleem
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Theodore R Holman
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Ganesha Rai
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Sarah A Tersey
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Raghavendra G Mirmira
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Medicine, Kovler Diabetes Center, The University of Chicago, Chicago, IL, USA
| | - Ryan M Anderson
- Department of Pediatrics, Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, USA,Department of Medicine, Kovler Diabetes Center, The University of Chicago, Chicago, IL, USA
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Aleem AM, Tsai WC, Tena J, Alvarez G, Deschamps J, Kalyanaraman C, Jacobson MP, Holman T. Probing the Electrostatic and Steric Requirements for Substrate Binding in Human Platelet-Type 12-Lipoxygenase. Biochemistry 2019; 58:848-857. [PMID: 30565457 DOI: 10.1021/acs.biochem.8b01167] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human platelet ALOX12 (hALOX12 or h12-LOX) has been implicated in a variety of human diseases. The present study investigates the active site of hALOX12 to more thoroughly understand how it positions the substrate and achieves nearly perfect regio- and stereospecificities (i.e., 100 ± 5% of the 12(S)-hydroperoxide product), utilizing site-directed mutagenesis. Specifically, we have determined that Arg402 is not as important in substrate binding as previously seen for hALOX15 but that His596 may play a role in anchoring the carboxy terminal of the arachidonic acid during catalysis. In addition, Phe414 creates a π-stacking interaction with a double bond of arachidonic acid (Δ11), and Ala417/Val418 define the bottom of the cavity. However, the influence of Ala417/Val418 on the profile is markedly less for hALOX12 than that seen in hALOX15. Mutating these two residues to larger amino acids (Ala417Ile/Val418Met) only increased the generation of 15-HpETE by 24 ± 2%, but conversely, smaller residues at these positions converted hALOX15 to almost 100% hALOX12 reactivity [Gan et al. (1996) J. Biol. Chem. 271, 25412-25418]. However, we were able to increase 15-HpETE to 46 ± 3% by restricting the width of the active site with the Ala417Ile/Val418Met/Ser594Thr mutation, indicating both depth and width of the active site are important. Finally, residue Leu407 is shown to play a critical role in positioning the substrate correctly, as seen by the increase of 15-HpETE to 21 ± 1% for the single Leu407Gly mutant. These results outline critical differences between the active site requirements of hALOX12 relative to hALOX15 and explain both their product specificity and inhibitory differences.
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Affiliation(s)
- Ansari Mukhtar Aleem
- Department of Chemistry and Biochemistry , University of California Santa Cruz , Santa Cruz , California 95064 , United States
| | - Wan-Chen Tsai
- Department of Chemistry and Biochemistry , University of California Santa Cruz , Santa Cruz , California 95064 , United States
| | - Jennyfer Tena
- Department of Chemistry and Biochemistry , University of California Santa Cruz , Santa Cruz , California 95064 , United States
| | | | - Joshua Deschamps
- Department of Chemistry and Biochemistry , University of California Santa Cruz , Santa Cruz , California 95064 , United States
| | - Chakrapani Kalyanaraman
- Department of Pharmaceutical Chemistry, School of Pharmacy , University of California San Francisco , San Francisco , California 94143 , United States
| | - Matthew P Jacobson
- Department of Pharmaceutical Chemistry, School of Pharmacy , University of California San Francisco , San Francisco , California 94143 , United States
| | - Theodore Holman
- Department of Chemistry and Biochemistry , University of California Santa Cruz , Santa Cruz , California 95064 , United States
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Al-Darwish AA, Al-Naim AF, Al-Mulhim KS, Al-Otaibi NK, Morsi MS, Aleem AM. Knowledge about cervical cancer early warning signs and symptoms, risk factors and vaccination among students at a medical school in Al-Ahsa, Kingdom of Saudi Arabia. Asian Pac J Cancer Prev 2015; 15:2529-32. [PMID: 24761859 DOI: 10.7314/apjcp.2014.15.6.2529] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cervical cancer is the second most common cancer among females and also the most preventable. In the literature there is abundant evidence that awareness regarding cervical cancer and its prevention is low in the developing countries. Medical students are the future health professionals and can play an important role in increasing awareness among the general population. To assess the knowledge regarding symptoms, risk factors and prevention of cervical carcinoma among medical students in th Kingdom of Saudi Arabia, the present study was planned. MATERIALS AND METHODS This cross-sectional study was conducted using a self-administered questionnaire with students at the College of Medicine, King Faisal University, Al-Ahsa, KSA, from December 2012 to May 2013. RESULTS The responses of 188 students (males 111, females 77) in their second, third, fourth, and fifth years were recorded and used in the data analysis. The majority of the students were not aware of the early warning signs, symptoms and risk factors. On average, only 43.7% males and 56% of females were aware about the early signs and symptoms whereas 51.4% males and 57.8% females had knowledge about the risk factors of cervical cancers. Some 55% males and 46.8% females were unable to select the correct answer regarding human papilloma virus (HPV) infection as the cause of cervical cancer. Majority of the students (67%) were not aware about the availability of vaccine against HPV. CONCLUSIONS Lack of knowledge regarding early signs and symptoms, risk factors and prevention of cervical cancer was observed in the present study.
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