RESUMEN
Hepatocellular carcinoma (HCC) is one of the most prevalent tumors worldwide and the leading contributor to cancer-related deaths. The progression and metastasis of HCC are closely associated with altered mitochondrial metabolism, including mitochondrial stress response. Mitokines, soluble proteins produced and secreted in response to mitochondrial stress, play an essential immunomodulatory role. Immunotherapy has emerged as a crucial treatment option for HCC. However, a positive response to therapy is typically dependent on the interaction of tumor cells with immune regulation within the tumor microenvironment. Therefore, exploring the specific immunomodulatory mechanisms of mitokines in HCC is essential for improving the efficacy of immunotherapy. This study provides a comprehensive overview of the association between HCC and the immune microenvironment and highlights recent progress in understanding the involvement of mitochondrial function in preserving liver function. In addition, a systematic review of mitokines-mediated immunomodulation in HCC is presented. Finally, the potential diagnostic and therapeutic roles of mitokines in HCC are prospected and summarized. Recent progress in mitokine research represents a new prospect for mitochondrial therapy. Considering the potential of mitokines to regulate immune function, investigating them as a relevant molecular target holds great promise for the diagnosis and treatment of HCC.
RESUMEN
Mechercharmycin A (MCM-A) is a marine natural product belonging to a family of polyazole cyclopeptides with remarkable bioactivities and unique structures. Identification, heterologous expression, and genetic characterizations of the MCM biosynthetic gene cluster in Bacillus subtilis revealed that it is a ribosomally synthesized and post-translationally modified peptide (RiPP) possessing complex with distinctive modifications. Based on this heterologous expression system, two MCM analogs with comparable antitumor activity are generated by engineering the biosynthetic pathway. Combinatorial co-production of a precursor peptide with different modifying enzymes in Escherichia coli identifies a different timing of modifications, showing that a tRNAGlu-dependent highly regioselective dehydration is the first modification step, followed by polyazole formation through heterocyclization and dehydrogenation in an N- to C-terminal direction. Therefore, a rational biosynthetic pathway of MCMs is proposed, which unveils a subfamily of azol(in)e-containing RiPPs and sets the stage for further investigations of the enzymatic mechanism and synthetic biology.
Asunto(s)
Péptidos Cíclicos , Ribosomas , Péptidos/química , Péptidos Cíclicos/metabolismo , Procesamiento Proteico-Postraduccional , Ribosomas/metabolismo , TiazolesRESUMEN
Using a highly effective heterologous expression system, the YM-216391 (1) biosynthetic gene cluster was engineered to yield aurantizolicin (2) and the hybrid compound 3. Both of these compounds were isolated and fully structurally characterised and the bioactivity was evaluated. The results indicate that compound 3 exhibits significantly improved antitumor activity.
Asunto(s)
Antineoplásicos/metabolismo , Vías Biosintéticas , Oxazoles/metabolismo , Péptidos Cíclicos/metabolismo , Streptomyces coelicolor/metabolismo , Streptomyces/metabolismo , Secuencia de Aminoácidos , Antineoplásicos/química , Antineoplásicos/farmacología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Genes Bacterianos , Ingeniería Genética , Humanos , Familia de Multigenes , Neoplasias/tratamiento farmacológico , Oxazoles/química , Oxazoles/farmacología , Péptidos Cíclicos/química , Péptidos Cíclicos/genética , Péptidos Cíclicos/farmacología , Streptomyces/química , Streptomyces/genética , Streptomyces coelicolor/química , Streptomyces coelicolor/genéticaRESUMEN
Cyclopropanation of unactivated olefinic bonds via addition of a reactive one-carbon species is well developed in synthetic chemistry, whereas natural cyclopropane biosynthesis employing this strategy is very limited. Here, we identify a two-component cyclopropanase system, composed of a HemN-like radical S-adenosyl-L-methionine (SAM) enzyme C10P and a methyltransferase C10Q, catalyzes chemically challenging cyclopropanation in the antitumor antibiotic CC-1065 biosynthesis. C10P uses its [4Fe-4S] cluster for reductive cleavage of the first SAM to yield a highly reactive 5'-deoxyadenosyl radical, which abstracts a hydrogen from the second SAM to produce a SAM methylene radical that adds to an sp2-hybridized carbon of substrate to form a SAM-substrate adduct. C10Q converts this adduct to CC-1065 via an intramolecular SN2 cyclization mechanism with elimination of S-adenosylhomocysteine. This cyclopropanation strategy not only expands the enzymatic reactions catalyzed by the radical SAM enzymes and methyltransferases, but also sheds light on previously unnoticed aspects of the versatile SAM-based biochemistry.
Asunto(s)
Antibióticos Antineoplásicos/biosíntesis , Proteínas Bacterianas/metabolismo , Ciclopropanos/metabolismo , Indoles/metabolismo , Metiltransferasas/metabolismo , S-Adenosilmetionina/metabolismo , Streptomyces/enzimología , Proteínas Bacterianas/genética , Biocatálisis , Clonación Molecular , Duocarmicinas , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Hierro/metabolismo , Proteínas Hierro-Azufre/genética , Proteínas Hierro-Azufre/metabolismo , Metiltransferasas/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , S-Adenosilhomocisteína/metabolismo , Streptomyces/genética , Azufre/metabolismoRESUMEN
As a commercial antibiotic, bicyclomycin (BCM) is currently the only known natural product targeting the transcription termination factor rho. It belongs to a family of highly functionalized diketopiperazine (DKP) alkaloids and bears a unique O-bridged bicyclo[4.2.2]piperazinedione ring system, a C1 triol, and terminal exo-methylene groups. We have identified and characterized the BCM biosynthetic pathway by heterologous biotransformations, inâ vitro biochemical assays, and one-pot enzymatic synthesis. A tRNA-dependent cyclodipeptide synthase guides the heterodimerization of leucine and isoleucine to afford the DKP precursor; subsequently, six redox enzymes, including five α-ketoglutarate/Fe2+ -dependent dioxygenases and one cytochrome P450 monooxygenase, regio- and stereoselectively install four hydroxy groups (primary, secondary, and two tertiary), an exo-methylene moiety, and a medium-sized bridged ring through the functionalization of eight unactivated C-H bonds.
Asunto(s)
Antibacterianos/metabolismo , Oxidorreductasas/química , Antibacterianos/química , Compuestos Bicíclicos Heterocíclicos con Puentes/química , Compuestos Bicíclicos Heterocíclicos con Puentes/metabolismo , Carbono/química , Cromatografía Liquida , Dimerización , Genes Bacterianos , Hidrógeno/química , Espectrometría de Masas , Familia de Multigenes , Péptido Sintasas/metabolismo , ARN de Transferencia/química , Streptomyces/genéticaRESUMEN
CC-1065 is the first characterized member of a family of naturally occurring antibiotics including yatakemycin and duocarmycins with exceptionally potent antitumor activity. CC-1065 contains three benzodipyrroles (1a-, 1b-, and 1c-) of which the 1a-subunit is remarkable by being composed of a cyclopropane ring, and the mechanism for the biological formation of benzodipyrrole rings remains elusive. Previously, biosynthetic studies of CC-1065 were limited to radioactively labeled precursor feeding experiments, which showed that tyrosine (Tyr) and serine (Ser) were incorporated into the two benzodipyrrole (1b- and 1c-) subunits via the same mode but that this was different from the key cyclopropabenzodipyrrole (1a-) subunit with N1-C2-C3 derived from Ser. Herein, the biosynthetic gene cluster of CC-1065 has been cloned, analyzed, and characterized by a series of gene inactivations. Significantly, a key intermediate bearing a C7-OH group derived from a Δc10C mutant exhibited improved cytotoxicity. Moreover, this data inspired us to suspect that the 1a-subunit might employ the same precursor incorporation mode as the 1b- and 1c-subunits. Subsequently, 13C-labeled Tyr feeding experiments confirmed that the N1-C2-C3 is originated from Tyr via DOPA as an intermediate. Collectively, a biosynthetic pathway of benzodipyrrole is proposed featuring a revised and unified precursor incorporation mode, which implicates an oxidative cyclization strategy for the assembly of benzodipyrrole. This work sets the stage for further study of enzymatic mechanisms and combinatorial biosynthesis for new DNA alkylating analogues.
Asunto(s)
Antibióticos Antineoplásicos/biosíntesis , Vías Biosintéticas , Indoles/metabolismo , Pirroles/química , Ciclización , Duocarmicinas , Indoles/química , Tirosina/metabolismoRESUMEN
Nonribosomal peptide synthetases (NRPSs) usually catalyze the biosynthesis of peptide natural products by sequential selection, activation, and condensation of amino acid precursors. It was reported that some fatty acids, α-ketoacids, and α-hydroxyacids originating from amino acid metabolism as well as polyketide-derived units can also be used by NRPS assembly lines as an alternative to amino acids. Ecteinascidin 743 (ET-743), naphthyridinomycin (NDM), and quinocarcin (QNC) are three important antitumor natural products belonging to the tetrahydroisoquinoline family. Although ET-743 has been approved as an anticancer drug, the origin of an identical two-carbon (C(2)) fragment among these three antibiotics has not been elucidated despite much effort in the biosynthetic research in the past 30 y. Here we report that two unexpected two-component transketolases (TKases), NapB/NapD in the NDM biosynthetic pathway and QncN/QncL in QNC biosynthesis, catalyze the transfer of a glycolaldehyde unit from ketose to the lipoyl group to yield the glycolicacyl lipoic acid intermediate and then transfer the C(2) unit to an acyl carrier protein (ACP) to form glycolicacyl-S-ACP as an extender unit for NRPS. Our results demonstrate a unique NRPS extender unit directly derived from ketose phosphates through (α,ß-dihydroxyethyl)-thiamin diphosphate and a lipoyl group-tethered ester intermediate catalyzed by the TKase-ACP platform in the context of NDM and QNC biosynthesis, all of which also highlights the biosynthesis of ET-743. This hybrid system and precursor are distinct from the previously described universal modes involving the NRPS machinery. They exemplify an alternate strategy in hybrid NRPS biochemistry and enrich the diversity of precursors for NRPS combinatorial biosynthesis.
Asunto(s)
Cetosas/metabolismo , Péptidos/metabolismo , Streptomyces/metabolismo , Proteína Transportadora de Acilo/genética , Proteína Transportadora de Acilo/metabolismo , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Vías Biosintéticas , Electroforesis en Gel de Poliacrilamida , Cetosas/química , Cinética , Espectroscopía de Resonancia Magnética , Modelos Químicos , Datos de Secuencia Molecular , Estructura Molecular , Familia de Multigenes , Mutación , Naftiridinas/química , Naftiridinas/metabolismo , Péptido Sintasas/genética , Péptido Sintasas/metabolismo , Péptidos/química , Péptidos/genética , Homología de Secuencia de Aminoácido , Streptomyces/química , Streptomyces/genética , Especificidad por Sustrato , Tetrahidroisoquinolinas/química , Tetrahidroisoquinolinas/metabolismo , Transcetolasa/genética , Transcetolasa/metabolismoRESUMEN
YM-216391, an antitumor natural product, represents a new class of cyclic peptides containing a polyoxazole-thiazole moiety. Herein we describe its gene cluster encoding the biosynthetic paradigm featuring a ribosomally synthesizing precursor peptide followed by a series of novel posttranslational modifications, which include (i) cleavage of both N-terminal leader peptide and C-terminal extension peptide and cyclization in a head-to-tail fashion, (ii) conversion of an L-Ile to D-allo-Ile, and (iii) ß-hydroxylation of Phe by a P450 monooxygenase followed by further heterocyclization and oxidation to form a phenyloxazole moiety. The cluster was heterologously expressed in Streptomyces lividans to bypass difficult genetic manipulation. Deletion of the ymR3 gene, encoding a putative transcriptional regulator, increased the YM-216391 yield about 20-fold higher than the original yields for the heterologous expression of wild-type cluster, which set the stage for further combinatorial biosynthesis.
Asunto(s)
Clonación Molecular/métodos , Familia de Multigenes , Péptidos Cíclicos/biosíntesis , Ingeniería de Proteínas/métodos , Antineoplásicos , Productos Biológicos , Genes Bacterianos , Oxazoles , Péptidos Cíclicos/genética , Streptomyces/genéticaRESUMEN
AIMS: To detect the level of serum syndecan-1 of patients with type 2 diabetes. METHODS: Subjects with diabetes were categorized into 4 subgroups, oral-agents, insulin therapy for