Unique Hexokinase Messenger Ribonucleic Acids Lacking the Porin-Binding Domain are Developmentally Expressed in Mouse Spermatogenic Cells1

Mori, Chisato; Welch, J. E.; Fulcher, Kerry D.; O’Brien, Deborah A.; Eddy, E. M.

doi:10.1095/biolreprod49.2.191

Cited by 79 publications

(84 citation statements)

References 47 publications

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“…35 Relatively little is known about the functions of non-bound HK1. PBD-lacking transcripts are expressed in mouse spermatogenic cells, with alternative splicing of the upstream exons subject to developmental regulation, 15,18 similar to our observations on AltT2-containing transcripts in the peripheral nerve. The translated protein is localised in the sperm tail and not with the mitochondria.…”

Section: Discussionsupporting

confidence: 86%

“…The analysis of neural tissue-derived mRNA identified six of the eight testis AltT2-containing isoforms, with expression patterns differing between the peripheral nerve and the brain and between newborn and adult tissues (Figure 2b). An interesting and functionally important feature of AltT2-containing transcripts, shared with the testis-specific isoforms described by Mori et al, 18 was the skipping of the PDB-encoding exon of somatic HK1. All AltT2-containing transcripts included the exon T3 ATG initiation codon and its surrounding sequence, referred to as the 'spermatogenic cell-specific region (SSR)'.…”

Section: Genetic Analysesmentioning

confidence: 79%

“…We characterised AltT2-containing transcripts in mouse newborn and adult neural tissues in comparison with the testis, which is particularly enriched in alternative splicing, 21 and where the HK1 5 0 upstream region has been studied in detail. 13,15,18 RT-PCR with different combinations of primers in exons T1 and AltT2 (forward), and T3 and ubiquitous 2 (reverse) revealed a total of 13 alternative transcripts. In both the testis and neural cells, the overall level of AltT2-containing transcripts was markedly lower than the invariable coding region of HK1 (not shown).…”

Section: Genetic Analysesmentioning

confidence: 99%

“…All AltT2-containing transcripts included the exon T3 ATG initiation codon and its surrounding sequence, referred to as the 'spermatogenic cell-specific region (SSR)'. 18 New HK1 transcripts are deposited in Genbank (accession numbers EU430519 -EU430533).…”

Section: Genetic Analysesmentioning

confidence: 99%

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A mutation in an alternative untranslated exon of hexokinase 1 associated with Hereditary Motor and Sensory Neuropathy – Russe (HMSNR)

et al. 2009

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Hereditary Motor and Sensory Neuropathy -Russe (HMSNR) is a severe autosomal recessive disorder, identified in the Gypsy population. Our previous studies mapped the gene to 10q22-q23 and refined the gene region to B70 kb. Here we report the comprehensive sequencing analysis and fine mapping of this region, reducing it to B26 kb of fully characterised sequence spanning the upstream exons of Hexokinase 1 (HK1). We identified two sequence variants in complete linkage disequilibrium, a G4C in a novel alternative untranslated exon (AltT2) and a G4A in the adjacent intron, segregating with the disease in affected families and present in the heterozygote state in only 5/790 population controls. Sequence conservation of the AltT2 exon in 16 species with invariable preservation of the G allele at the mutated site, strongly favour the exonic change as the pathogenic mutation. Analysis of the Hk1 upstream region in mouse mRNA from testis and neural tissues showed an abundance of AltT2-containing transcripts generated by extensive, developmentally regulated alternative splicing. Expression is very low compared with ubiquitous Hk1 and all transcripts skip exon1, which encodes the protein domain responsible for binding to the outer mitochondrial membrane, and regulation of energy production and apoptosis. Hexokinase activity measurement and immunohistochemistry of the peripheral nerve showed no difference between patients and controls. The mutational mechanism and functional effects remain unknown and could involve disrupted translational regulation leading to increased anti-apoptotic activity (suggested by the profuse regenerative activity in affected nerves), or impairment of an unknown HK1 function in the peripheral nervous system (PNS).

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Section: Discussionsupporting

confidence: 86%

Section: Genetic Analysesmentioning

confidence: 79%

Section: Genetic Analysesmentioning

confidence: 99%

Section: Genetic Analysesmentioning

confidence: 99%

See 2 more Smart Citations

A mutation in an alternative untranslated exon of hexokinase 1 associated with Hereditary Motor and Sensory Neuropathy – Russe (HMSNR)

et al. 2009

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“…Three isozymes, glyceraldehyde 3-phosphate dehydrogenase-S (GAPDS), phosphoglycerate kinase-2, and lactate dehydrogenase-C 4 , are encoded by paralogous genes expressed only during spermatogenesis (5, 9-13). At least five other enzymes in the glycolytic pathway have unique structural or functional properties in spermatogenic cells (6,(14)(15)(16)(17)(18). GAPDS, one of the germ cell-specific isozymes, is tightly bound to the fibrous sheath, a cytoskeletal structure that defines the limits of the principal piece (4).…”

mentioning

confidence: 99%

Glyceraldehyde 3-phosphate dehydrogenase-S, a sperm-specific glycolytic enzyme, is required for sperm motility and male fertility

Miki

Goulding

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

544

457

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Although glycolysis is highly conserved, it is remarkable that several unique isozymes in this central metabolic pathway are found in mammalian sperm. Glyceraldehyde 3-phosphate dehydrogenase-S (GAPDS) is the product of a mouse gene expressed only during spermatogenesis and, like its human ortholog (GAPD2), is the sole GAPDH isozyme in sperm. It is tightly bound to the fibrous sheath, a cytoskeletal structure that extends most of the length of the sperm flagellum. We disrupted Gapds expression by gene targeting to selectively block sperm glycolysis and assess its relative importance for in vivo sperm function. Gapds ؊/؊ males were infertile and had profound defects in sperm motility, exhibiting sluggish movement without forward progression. Although mitochondrial oxygen consumption was unchanged, sperm from Gapds ؊/؊ mice had ATP levels that were only 10.4% of those in sperm from WT mice. These results imply that most of the energy required for sperm motility is generated by glycolysis rather than oxidative phosphorylation. Furthermore, the critical role of glycolysis in sperm and its dependence on this sperm-specific enzyme suggest that GAPDS is a potential contraceptive target, and that mutations or environmental agents that disrupt its activity could lead to male infertility. glycolysis ͉ gene targeting ͉ infertility S perm motility is essential for normal fertilization, and asthenozoospermia, or low sperm motility, is common in infertile men. In a recent study of 1,085 sperm samples from infertile men, 81% had defects in motility, and 19% had asthenozoospermia without other defects in sperm number or morphology (1). Motility is generated by the extremely long flagellum that comprises Ͼ90% of the length of a mammalian sperm. This process requires substantial ATP to support coordinated movement of the central axoneme and surrounding flagellar structures (2). ATP is hydrolyzed by dynein ATPases, which function as force-generating molecular motors along the axoneme. Although quiescent in the epididymis, mammalian sperm display vigorous forward movement, termed activated or progressive motility, immediately upon ejaculation or collection into physiological medium. The motility waveform changes in the female reproductive tract, with increases in both the amplitude and asymmetry of flagellar bending. These changes result in a whiplash-like motion, termed hyperactivated motility, which facilitates sperm transport in the oviduct and penetration of the zona pellucida surrounding the oocyte (3).Potential sources of ATP to support sperm motility are compartmentalized in distinct regions along the length of the flagellum. Oxidative phosphorylation is confined to the proximal segment of the flagellum where the mitochondria are localized (middle piece). In contrast, glycolysis appears to be restricted to the principal piece, which is distal to the middle piece and is the longest segment of the sperm flagellum (4-8). Several glycolytic enzymes in mammalian sperm are distinct from the isozymes present in somatic tissues. Thr...

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Properties and localization of a tyrosine phosphorylated form of hexokinase in mouse sperm

et al. 1996

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Mouse sperm possess a phosphotyrosine‐containing hexokinase type 1 (HK1) that is associated with the plasma membrane fraction of these cells (Kalab et al., 1994; J. Biol Chem 269:3810–3817.). This apparent plasma membrane association appears unique, since somatic HK1 is normally cytoplasmic or bound to the outer mitochondrial membrane via contact sites with a voltage‐dependent anion channel (porin) through a porin‐binding domain. In male germ cells, three cDNA clones have been described that encode unique HK1 isoforms (HK1‐sa, HK1‐sb, HK1‐sc) that do not contain porin binding domains (Mori et al., 1993: Biol Reprod 49:191–203). This suggests that these proteins might not be localized to the outer mitochondrial membrane and could have alternative functions in germ cells and/or sperm. We demonstrate in the mouse that male germ cells and sperm could potentially express four HK1 isoforms (HK1‐sa, HK1‐sb, HK1‐sc, and the somatic HK1). At the protein level, at least one of the HK1 isoforms becomes phosphorylated on tyrosine residues during spermatogenesis. Treatment of sperm membrane fractions to dissociate the phosphotyrosine‐containing HK1 (pY‐mHK1) yields results demonstrating that pY‐mHK1 has properties of an integral membrane protein. Indirect immunofluorescence using a monoclonal antibody to HK1 demonstrates specific staining both in the head and tail regions of sperm. Surface biotinylation of intact sperm followed by precipitation with either polyclonal HK1 antiserum or with avidin‐Sepharose suggests that pY‐mHK1 possesses an extracellular domain. These results suggest that mouse sperm contain at least one HK1 isoform that is present on the sperm head, has an extracellular domain, and behaves as an integral membrane protein. © 1996 Wiley‐Liss, Inc.

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Unique Hexokinase Messenger Ribonucleic Acids Lacking the Porin-Binding Domain are Developmentally Expressed in Mouse Spermatogenic Cells1

Cited by 79 publications

References 47 publications

A mutation in an alternative untranslated exon of hexokinase 1 associated with Hereditary Motor and Sensory Neuropathy – Russe (HMSNR)

A mutation in an alternative untranslated exon of hexokinase 1 associated with Hereditary Motor and Sensory Neuropathy – Russe (HMSNR)

Glyceraldehyde 3-phosphate dehydrogenase-S, a sperm-specific glycolytic enzyme, is required for sperm motility and male fertility

Properties and localization of a tyrosine phosphorylated form of hexokinase in mouse sperm

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