Department of biochemistry and Molecular biology
Sergey Krupenko, PhD
My research interests lay in the area of protein structure and function, enzyme mechanisms and enzyme regulation. At present my lab is focused on studies of one of the major enzymes of folate metabolism. Folate coenzymes carry out one-carbon transfers and play an essential role in several major cellular processes, including nucleic acid biosynthesis, mitochondrial and choloroplast protein biosynthesis, amino acid metabolism, methyl group biogenesis, vitamin metabolism and DNA/protein methylation. Higher animals are unable to synthesize folate and thus depend on the diet to provide the folate necessary for their metabolic function. Folate deficiency causes a number of severe disorders, increases the risk of vascular disease and also causes uracil misincorporation into DNA and chromosome breakage that is implicated in progression of cancer. Numerous enzymes are involved in folate metabolism interconverting the coenzymes by transferring one-carbon units. The multifunctional multidomain enzyme, 10-formyltetrahydrofolate dehydrogenase (FDH) regulates 10-formyltetrahydrofolate and tetrahydrofolate pools converting 10-formyltetrahydrofolate to tetrahydrofolate. The enzyme is a natural fusion of two unrelated proteins and has two catalytic centers, which work in concert to create enzyme activity. The mainstream project in my lab is directed to explore FDH structure and mechanism. This includes: characterization of the folate binding site of FDH and identification of amino acid residues important for folate binding and catalysis; study of the mechanisms of FDH activation; study of FDH oligomerization; resolution of the crystal structure of FDH and its domains expressed as separate proteins; study of the role of the flexibility of FDH domains in the protein structure and enzyme regulation. FDH substrate, 10-formyltetrahydrofolate, is also a substrate for two reactions in the de novo purine biosynthesis pathway. This allowed us to hypothesize that FDH may regualte purine biosynthesis by controlling the level of 10-formyltetrahydrofolate, thus influencing cellular metabolism. We have recently discovered that overexpression of FDH suppresses growth of several types of cancer cells. We have further observed that this enzyme being abundant in normal tissues is absent in most cancers. This suggests that in order to proliferate, cancer cells must "turn off" the enzyme and, in opposite, high enzyme levels will inhibit cancer cell proliferation. We propose that this enzyme suppresses cancer cells through inhibition of biosynthesis of purines, DNA/RNA precursors, thus inhibiting nucleic acid biosynthesis and cell growth/proliferation. This can also influence DNA repair and other purine-dependent processes that might contribute in the FDH suppressor effects and cancer cell apoptosis. The enzyme might also be relevant to individual proclivity of patients to carcinogenesis: its lower levels in certain types of tissues might indicate preexisting conditions for tumor development or early stages of initiated oncogenesis. Therefore, we have recently started a new project to investigate the role of FDH as a tumor suppressor, to explore the mechanisms of inhibitory effects of FDH on cancer cells and to elucidate the role of the enzyme in carcinogenesis. These studies apply cell culture models, human tumor xenografts in nude mice and apoptosis-related techniques to address the above questions. FDH will be further evaluated as a potential target for gene therapy.
Recent Publications | Additional Publications
Debroy S, Kramarenko II, Ghose S, Oleinik NV, Krupenko SA, Krupenko NI. A novel tumor suppressor function of glycine N-methyltransferase is independent of its catalytic activity but requires nuclear localization. PLoS One. 2013 Jul 30;8(7):e70062. doi: 10.1371/journal.pone.0070062. Print 2013. PMID: 23936142 [PubMed - in process]
Hoeferlin LA, Fekry B, Ogretmen B, Krupenko SA, Krupenko NI. Folate stress induces apoptosis via p53-dependent de novo ceramide synthesis and up-regulation of ceramide synthase 6. J Biol Chem. 2013 May 3;288(18):12880-90. doi: 10.1074/jbc.M113.461798. Epub 2013 Mar 21. PMID: 23519469 [PubMed - indexed for MEDLINE]
Strickland KC, Krupenko NI, Krupenko SA. Molecular mechanisms underlying the potentially adverse effects of folate. Clin Chem Lab Med. 2013 Mar 1;51(3):607-16. doi: 10.1515/cclm-2012-0561.
Hoeferlin LA, Oleinik NV, Krupenko NI, Krupenko SA. Activation of p21-dependent G1/G2 arrest in the absence of DNA damage as an antiapoptotic response to metabolic stress. Genes Cancer. 2011 Sep;2(9):889-99. PubMed PMID: 22593801; PubMed Central PMCID: PMC3352155.
Tsybovsky Y, Malakhau Y, Strickland KC, Krupenko SA. The mechanism of discrimination between oxidized and reduced coenzyme in the aldehyde dehydrogenase domain of Aldh1l1. Chem Biol Interact. 2013 Feb 25;202(1-3):62-9. doi: 10.1016/j.cbi.2012.12.015. Epub 2013 Jan 5. PMID: 23295222 [PubMed - indexed for MEDLINE]
Oleinik NV, Krupenko NI, Krupenko SA. Epigenetic silencing of ALDH1L1, a metabolic regulator of cellular proliferation in cancers. Genes Cancer. 2011 Feb;2(2):130-9. PubMed PMID: 21779486; PubMed Central PMCID: PMC3111244.
Carrasco MP, Enyedy EA, Krupenko NI, Krupenko SA, Nuti E, Tuccinardi T, Santamaria S, Rossello A, Martinelli A, Santos MA. Novel folate-hydroxamate based antimetabolites: synthesis and biological evaluation. Med Chem. 2011 Jul;7(4):265-74. PubMed PMID: 21568878.
Tsybovsky Y, Krupenko SA. Conserved catalytic residues of the ALDH1L1 aldehyde dehydrogenase domain control binding and discharging of the coenzyme. J Biol Chem. 2011 Jul 1;286(26):23357-67. Epub 2011 May 3. PubMed PMID: 21540484; PubMed Central PMCID: PMC3123100.
Strickland KC, Krupenko NI, Dubard ME, Hu CJ, Tsybovsky Y, Krupenko SA. Enzymatic properties of ALDH1L2, a mitochondrial 10-formyltetrahydrofolate dehydrogenase. Chem Biol Interact. 2011 May 30;191(1-3):129-36. Epub 2011 Jan 14. PubMed PMID: 21238436; PubMed Central PMCID: PMC3103650.
Strickland KC, Holmes RS, Oleinik NV, Krupenko NI, Krupenko SA. Phylogeny and evolution of aldehyde dehydrogenase-homologous folate enzymes. Chem Biol Interact. 2011 May 30;191(1-3):122-8. Epub 2011 Jan 6. PubMed PMID: 21215736; PubMed Central PMCID: PMC3103616.
Oleinik NV, Krupenko NI, Krupenko SA. ALDH1L1 inhibits cell motility via dephosphorylation of cofilin by PP1 and PP2A. Oncogene. 2010 Nov 25;29(47):6233-44. Epub 2010 Aug 23. PubMed PMID: 20729910; PubMed Central PMCID: PMC2992098.
Marques SM, Enyedy EA, Supuran CT, Krupenko NI, Krupenko SA, Santos MA. Pteridine-sulfonamide conjugates as dual inhibitors of carbonic anhydrases and dihydrofolate reductase with potential antitumor activity. Bioorg Med Chem. 2010 Jul 15;18(14):5081-9. Epub 2010 Jun 2. PubMed PMID: 20580561.
Krupenko NI, Dubard ME, Strickland KC, Moxley KM, Oleinik NV, Krupenko SA. ALDH1L2 is the mitochondrial homolog of 10-formyltetrahydrofolate dehydrogenase. J Biol Chem. 2010 May 24. [Epub ahead of print] PubMed PMID: 20498374.
Strickland KC, Hoeferlin LA, Oleinik NV, Krupenko NI, Krupenko SA. Acyl carrier protein-specific 4'-phosphopantetheinyl transferase activates 10-formyltetrahydrofolate dehydrogenase. J Biol Chem. 2010 Jan 15;285(3):1627-33. Epub 2009 Nov 20. PubMed PMID: 19933275; PubMed Central PMCID: PMC2804320.
Ghose S, Oleinik NV, Krupenko NI, Krupenko SA. 10-formyltetrahydrofolate dehydrogenase-induced c-Jun-NH2-kinase pathways diverge at the c-Jun-NH2-kinase substrate level in cells with different p53 status. Mol Cancer Res. 2009 Jan;7(1):99-107. PubMed PMID: 19147541; PubMed Central PMCID: PMC2632845.
Celtikci B, Leclerc D, Lawrance AK, Deng L, Friedman HC, Krupenko NI, Krupenko SA, Melnyk S, James SJ, Peterson AC, Rozen R. Altered expression of methylenetetrahydrofolate reductase modifies response to methotrexate in mice. Pharmacogenet Genomics. 2008 Jul;18(7):577-89. PubMed PMID: 18551038.
Krupenko SA. FDH: an aldehyde dehydrogenase fusion enzyme in folate metabolism. Chem Biol Interact. 2009 Mar 16;178(1-3):84-93. Epub 2008 Sep 19. Review. PubMed PMID: 18848533; PubMed Central PMCID: PMC2664990.