NovelGNE mutations in Italian families with autosomal recessive hereditary inclusion-body myopathy
ABSTRACT The most common form of autosomal recessive (AR) hereditary inclusion-body myopathy (HIBM), originally described in Persian-Jewish families, is characterized by onset in early adult life with weakness and atrophy of distal lower limb muscles, which progress proximally and relatively spare the quadriceps. AR HIBM is associated with mutations in the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase gene (GNE) on chromosome 9p12-13. In the present study we have identified seven novel GNE mutations in patients from five unrelated Italian families with clinical and pathologic features indicative of AR HIBM. Four were missense mutations (c.1556A>G [p.N519S], c.79C>T [p.P27S], c.1798G>A [p.A600T] and c.616G>A [p.G206S]), two consisted in a single-base deletion (c.616delG [p.G206fsX4] and c.1130delT [p.I377fsX16]) and one in an intronic single-base insertion (c.1070+2dupT). These latter findings further extend the type of GNE mutations associated with HIBM. Furthermore, in one patient we also identified the c.737G>A [p.R246Q] missense mutation that corresponds to the one previously reported in a family from the Bahamas. Interestingly, in two of our families distinct mutations affected nucleotide c.616 in exon 3 (c.616delG and c.616G>A). The possibility of specific portions of the gene being more prone to mutations remains to be elucidated.
Full-textDOI: · Available from: Massimiliano Mirabella, Sep 29, 2014
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- "Amino acid substitution GNE exon Structural position (domain b , secondary structure, function) References 45 p.N519S 9 Kinase, α4; vicinity of the glucose and magnesium binding sites; Ser is present in structurally equivalent position of the Mlc protein, which does not bind glucose (Figure 1B); helix–helix contacts rearranged in Mlc; changes in the predicted secondary structure by CD spectroscopy (Penner et al. 2006) Broccolini et al. 2004 46 p.A524V 9 Kinase, α4; interface between α4 (glucose and magnesium binding helix) and α11; Ala is conserved among structurally similar proteins except HKI carrying Thr Behin et al. 2008 Darvish et al. 2002 Liewluck et al. 2006 47 p.F528C 9 Kinase, α4; interface between α4 (glucose and magnesium binding helix) and α11 Eisenberg et al. 2003 48 p.I557T 10 Kinase, β8; part of a ROK motif 1 Eisenberg et al. 2003 Tomimitsu et al. 2004 49 p.G559R 10 Kinase, β8α5; part of a ROK motif 1 Huizing et al. 2004 50 p.V572L 10 Kinase, α5α6; connection region between ROK motifs 1 and 2; vicinity of zinc and glucose binding; may be part of dimerization interface (Penner et al. 2006) Kayashima et al. 2002 Kim et al. 2006 Tomimitsu et al. 2002 51 p.G576E 10 Kinase, α5α6; vicinity of a zinc and substrate binding site (ROK motif 2); structural changes affect the dimerization interface due to introduction of a glutamyl side chain, resulting in trimer formation (instead of hexamer) (Penner et al. 2006) Eisenberg et al. 2001 52 p.I587T 10 Kinase, α6; vicinity of a zinc and substrate binding site (ROK motif 2) Behin et al. 2008 Eisenberg et al. 2003 53 p.A591T 10 Kinase, α6; interface with α6 Kim et al. 2006 54 p.A600T 10 Kinase, α6 ; interfaces with α7, α8, α9 Broccolini et al. 2004 55 p.A630T 11 Kinase, α7; vicinity of ADP binding; interface with α6 Nishino et al. 2002 56 p.A631T 11 Kinase, α7; vicinity of ADP binding; interface with α6 Behin et al. 2008 Eisenberg et al. 2001 57 p.A631V 11 Kinase, α7; vicinity of ADP binding; interface with α6 Nishino et al. 2002 Eisenberg et al. 2003 Tomimitsu et al. 2002 Vasconcelos et al. "
ABSTRACT: The bifunctional enzyme UDP-GlcNAc 2-epimerase/ ManNAc kinase (GNE/MNK), encoded by the GNE gene, catalyzes the first two committed, rate-limiting steps in the biosynthesis of N-acetylneuraminic acid (sialic acid). GNE/MNK is feedback inhibited by binding of the downstream product, CMP-sialic acid in its allosteric site. GNE mutations can result in two human disorders, hereditary inclusion body myopathy (HIBM) or sialuria. So far, no active site geometry predictions or conformational transitions involved with function are available for mammalian GNE/MNK. The N-terminal GNE domain is homologous to various prokaryotic 2-epimerases, some of which have solved crystallographic structures. The C-terminal MNK domain belongs to the sugar kinases superfamily; its crystallographic structure is solved at 2.84 A and three-dimensional structures have also been reported for several other kinases. In this work, we employed available structural data of GNE/MNK homologs to model the active sites of human GNE/MNK and identify critical amino acid residues responsible for interactions with substrates. In addition, we modeled effects of GNE/MNK missense mutations associated with HIBM or sialuria on helix arrangement, substrate binding, and enzyme action. We found that all reported mutations are associated with the active sites or secondary structure interfaces of GNE/MNK. The Persian-Jewish HIBM founder mutation p.M712T is located at the interface alpha4alpha10 and likely affects GlcNAc, Mg2+, and ATP binding. This work contributes to further understanding of GNE/MNK function and ligand binding, which may assist future studies for therapeutic options that target misfolded GNE/MNK in HIBM and/or sialuria.Glycobiology 11/2009; 20(3):322-37. DOI:10.1093/glycob/cwp176 · 3.14 Impact Factor
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- ", p. R246W or p.R246Q [19,22,28–30], p.303V or p.303X  , p.P511H or p.P511L  , and p.A631T and p.A631V     . Also some specific GNE mutations arose presumably independently in multiple ethnicities: p.R246Q in Italy, Bahamas and Taiwan   , p.D378Y in Japan and Ireland  , p.A524V in Thailand, Mexico and France   , p.I557T in Italy and Japan  , p. A631V in Germany, Ireland and Japan   , and p.V696M in Thailand, India and Algeria    . Fig. 1 "
ABSTRACT: Hereditary Inclusion Body Myopathy (HIBM) is an autosomal recessive, quadriceps sparing type commonly referred to as HIBM but also termed h-IBM or Inclusion Body Myopathy 2 (IBM2). The clinical manifestations begin with muscle weakness progressing over the next 10–20 years uniquely sparing the quadriceps until the most advanced stage of the disease. Histopathology of an HIBM muscle biopsy shows rimmed vacuoles on Gomori's trichrome stain, small fibers in groups and tubulofilaments without evidence of inflammation. In affected individuals distinct mutations have been identified in the GNE gene, which encodes the bifunctional enzyme uridine diphospho-N-acetylglucosamine (UDP-GlcNAc) 2-epimerase/N-acetyl-mannosamine (ManNAc) kinase (GNE/MNK). GNE/MNK catalyzes the first two committed steps in the biosynthesis of acetylneuraminic acid (Neu5Ac), an abundant and functionally important sugar. The generation of HIBM animal models has led to novel insights into both the disease and the role of GNE/MNK in pathophysiology. Recent advances in therapeutic approaches for HIBM, including administration of N-acetyl-mannosamine (ManNAc), a precursor of Neu5Ac will be discussed.Biochimica et Biophysica Acta 09/2009; 1792(9-1792):881-887. DOI:10.1016/j.bbadis.2009.07.001 · 4.66 Impact Factor
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- "GNE is a highly conserved gene identifi ed as 1 of 40 genes exclusively shared by vertebrates and bacteria (Salzberg, White et al. 2001). It encodes the bifunctional enzyme uridine diphosphate-N-acetylglucosamine 2—epimerase/N-acetylmannosamine kinase (GNE/MNK) which catalyzes the fi rst two sequential sialic acid pathway reactions critical to sialic acid synthesis, and HIBM2 mutations are distributed over the whole enzyme (Argov, Eisenberg et al. 2003; Krause, Schlotter-Weigel et al. 2003; Broccolini, Ricci et al. 2004; Huizing, Rakocevic et al. 2004; Saito, Tomimitsu et al. 2004). "
ABSTRACT: Hereditary Inclusion Body Myopathy (HIBM2) is a chronic progressive skeletal muscle wasting disorder which generally leads to complete disability before the age of 50 years. There is currently no effective therapeutic treatment for HIBM2. Development of this disease is related to expression in family members of an autosomal recessive mutation of the GNE gene, which encodes the bifunctional enzyme UDP-GlcNAc 2-epimerase/ManNAc kinase (GNE/MNK). This is the rate limiting bifunctional enzyme that catalyzes the first 2 steps of sialic acid biosynthesis. Decreased sialic acid production, consequently leads to decreased sialyation of a variety of glycoproteins including the critical muscle protein alpha-dystroglycan (alpha-DG). This in turn severely cripples muscle function and leads to the onset of the syndrome. We hypothesize that replacing the mutated GNE gene with the wildtype gene may restore functional capacity of GNE/MNK and therefore production of sialic acid, allowing for improvement in muscle function and/or delay in rate of muscle deterioration. We have constructed three GNE gene/CMV promoter plasmids (encoding the wildtype, HIBM2, and Sialuria forms of GNE) and demonstrated enhanced GNE gene activity following delivery to GNE-deficient CHO-Lec3 cells. GNE/MNK enzyme function was significantly increased and subsequent induction of sialic acid production was demonstrated after transfection into Lec3 cells with the wild type or R266Q mutant GNE vector. These data form the foundation for future preclinical and clinical studies for GNE gene transfer to treat HIBM2 patients.Gene regulation and systems biology 06/2008; 2:243-52.