MYO7A

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Myosin VIIA
Identifiers
Symbols	MYO7A ; DFNA11; DFNB2; MYOVIIA; MYU7A; NSRD2; USH1B
External IDs	OMIM: 276903 MGI: 104510 HomoloGene: 219 GeneCards: MYO7A Gene
Gene ontology Molecular function • microfilament motor activity • protein binding • calmodulin binding • ATP binding • protein domain specific binding • spectrin binding • actin-dependent ATPase activity • protein homodimerization activity • ADP binding • protein N-terminus binding • actin filament binding Cellular component • photoreceptor outer segment • photoreceptor inner segment • cytoplasm • lysosomal membrane • cytosol • cell cortex • apical plasma membrane • myosin VII complex • photoreceptor connecting cilium • stereocilium • melanosome • synapse • upper tip-link density Biological process • phagolysosome assembly • intracellular protein transport • lysosome organization • visual perception • sensory perception of sound • metabolic process • actin filament-based movement • eye photoreceptor cell development • post-embryonic organ morphogenesis • sensory perception of light stimulus • equilibrioception • pigment granule transport • auditory receptor cell stereocilium organization Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	4647	17921
Ensembl	ENSG00000137474	ENSMUSG00000030761
UniProt	Q13402	P97479
RefSeq (mRNA)	NM_000260	NM_001256081
RefSeq (protein)	NP_000251	NP_001243010
Location (UCSC)	Chr 11: 77.13 – 77.22 Mb	Chr 7: 98.05 – 98.12 Mb
PubMed search

Myosin VIIA is protein that in humans is encoded by the MYO7A gene.^[1] Myosin VIIA is a member of the unconventional myosin superfamily of proteins.^[2] Myosins are actin binding molecular motors that use the enzymatic conversion of ATP - ADP + inorganic phosphate (Pi) to provide the energy for movement.

Myosins are mechanochemical proteins characterized by the presence of a motor domain, an actin-binding domain, a neck domain that interacts with other proteins, and a tail domain that serves as an anchor. Myosin VIIA is an unconventional myosin with a very short tail. Unconventional myosins have diverse functions in eukaryotic cells and are primarily thought to be involved in the movement or linkage of intra-cellular membranes and organelles to the actin cytoskeleton via interactions mediated by their highly divergent tail domains.

MYO7A is expressed in a number of mammalian tissues, including testis, kidney, lung, inner ear, retina and the ciliated epithelium of the nasal mucosa.

Clinical significance

Mutations in the MYO7A gene cause the Usher syndrome type 1B, a combined deafness/blindness disorder.^[2] Affected individuals are typically profoundly deaf at birth and then undergo progressive retinal degeneration.^[3]

Model organisms

Myo7a mutant mouse phenotype

Characteristic	Phenotype
Homozygote viability	Normal
Fertility	Normal
Body weight	Abnormal[4]
Anxiety	Normal
Neurological assessment	Abnormal[5]
Grip strength	Abnormal[6]
Hot plate	Abnormal[7]
Dysmorphology	Normal
Indirect calorimetry	Abnormal[8]
Glucose tolerance test	Abnormal[9]
Auditory brainstem response	Abnormal
DEXA	Abnormal[10]
Radiography	Abnormal[11]
Body temperature	Normal
Eye morphology	Normal
Clinical chemistry	Abnormal[12]
Plasma immunoglobulins	Normal
Haematology	Normal
Peripheral blood lymphocytes	Normal
Micronucleus test	Normal
Heart weight	Normal
Tail epidermis wholemount	Normal
Skin Histopathology	Normal
All tests and analysis from[13][14]

Model organisms have been used in the study of MYO7A function. A spontaneous mutant mouse line, called Myo7a^sh1-6J[15] was generated. Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.^[13][16] Twenty three tests were carried out on mutant mice and ten significant abnormalities were observed.^[13] Male homozygous mutant mice displayed a decreased body weight, a decrease in body fat, improved glucose tolerance and abnormal pelvic girdle bone morphology. Homozygous mutant mice of both sex displayed various abnormalities in a modified SHIRPA test, including abnormal gait, tail dragging and an absence of pinna reflex, a decrease in grip strength, an increased thermal pain threshold, severe hearing impairment and a number of abnormal indirect calorimetry and clinical chemistry parameters.^[13]

References

1. Hasson T, Skowron JF, Gilbert DJ, Avraham KB, Perry WL, Bement WM, Anderson BL, Sherr EH, Chen ZY, Greene LA, Ward DC, Corey DP, Mooseker MS, Copeland NG, Jenkins NA (Sep 1996). "Mapping of unconventional myosins in mouse and human". Genomics 36 (3): 431–9. doi:10.1006/geno.1996.0488. PMID 8884266.
2. Weil D, Blanchard S, Kaplan J, Guilford P, Gibson F, Walsh J, Mburu P, Varela A, Levilliers J, Weston MD (Mar 1995). "Defective myosin VIIA gene responsible for Usher syndrome type 1B". Nature 374 (6517): 60–1. doi:10.1038/374060a0. PMID 7870171.
3. Smith RJ, Berlin CI, Hejtmancik JF, Keats BJ, Kimberling WJ, Lewis RA, Möller CG, Pelias MZ, Tranebjaerg L (Mar 1994). "Clinical diagnosis of the Usher syndromes. Usher Syndrome Consortium". American Journal of Medical Genetics 50 (1): 32–8. doi:10.1002/ajmg.1320500107. PMID 8160750.
4. "Body weight data for Myo7a". Wellcome Trust Sanger Institute.
5. "Neurological assessment data for Myo7a". Wellcome Trust Sanger Institute.
6. "Grip strength data for Myo7a". Wellcome Trust Sanger Institute.
7. "Hot plate data for Myo7a". Wellcome Trust Sanger Institute.
8. "Indirect calorimetry data for Myo7a". Wellcome Trust Sanger Institute.
9. "Glucose tolerance test data for Myo7a". Wellcome Trust Sanger Institute.
10. "DEXA data for Myo7a". Wellcome Trust Sanger Institute.
11. "Radiography data for Myo7a". Wellcome Trust Sanger Institute.
12. "Clinical chemistry data for Myo7a". Wellcome Trust Sanger Institute.
13. Gerdin AK (2010). "The Sanger Mouse Genetics Programme: High throughput characterisation of knockout mice". Acta Ophthalmologica 88: 925–7. doi:10.1111/j.1755-3768.2010.4142.x.
14. Mouse Resources Portal, Wellcome Trust Sanger Institute.
15. "Mouse Genome Informatics".
16. van der Weyden L, White JK, Adams DJ, Logan DW (2011). "The mouse genetics toolkit: revealing function and mechanism". Genome Biology 12 (6): 224. doi:10.1186/gb-2011-12-6-224. PMC 3218837. PMID 21722353.

External links

• GeneReviews/NCBI/NIH/UW entry on Usher Syndrome Type I

Further reading

• Wolfrum U (2004). "The cellular function of the usher gene product myosin VIIa is specified by its ligands". Advances in Experimental Medicine and Biology 533: 133–42. doi:10.1007/978-1-4615-0067-4_17. PMID 15180257.
• el-Amraoui A, Sahly I, Picaud S, Sahel J, Abitbol M, Petit C (Aug 1996). "Human Usher 1B/mouse shaker-1: the retinal phenotype discrepancy explained by the presence/absence of myosin VIIA in the photoreceptor cells". Human Molecular Genetics 5 (8): 1171–8. doi:10.1093/hmg/5.8.1171. PMID 8842737.
• Adato A, Weil D, Kalinski H, Pel-Or Y, Ayadi H, Petit C, Korostishevsky M, Bonne-Tamir B (Oct 1997). "Mutation profile of all 49 exons of the human myosin VIIA gene, and haplotype analysis, in Usher 1B families from diverse origins". American Journal of Human Genetics 61 (4): 813–21. doi:10.1086/514899. PMC 1716000. PMID 9382091.
• Liu XZ, Hope C, Walsh J, Newton V, Ke XM, Liang CY, Xu LR, Zhou JM, Trump D, Steel KP, Bundey S, Brown SD (Sep 1998). "Mutations in the myosin VIIA gene cause a wide phenotypic spectrum, including atypical Usher syndrome". American Journal of Human Genetics 63 (3): 909–12. doi:10.1086/302026. PMC 1377414. PMID 9718356.
• Kimberling WJ, Möller CG, Davenport S, Priluck IA, Beighton PH, Greenberg J, Reardon W, Weston MD, Kenyon JB, Grunkemeyer JA (Dec 1992). "Linkage of Usher syndrome type I gene (USH1B) to the long arm of chromosome 11". Genomics 14 (4): 988–94. doi:10.1016/S0888-7543(05)80121-1. PMID 1478677.
• Hasson T, Heintzelman MB, Santos-Sacchi J, Corey DP, Mooseker MS (Oct 1995). "Expression in cochlea and retina of myosin VIIa, the gene product defective in Usher syndrome type 1B". Proceedings of the National Academy of Sciences of the United States of America 92 (21): 9815–9. doi:10.1073/pnas.92.21.9815. PMC 40893. PMID 7568224.
• Guilford P, Ayadi H, Blanchard S, Chaib H, Le Paslier D, Weissenbach J, Drira M, Petit C (Jun 1994). "A human gene responsible for neurosensory, non-syndromic recessive deafness is a candidate homologue of the mouse sh-1 gene". Human Molecular Genetics 3 (6): 989–93. doi:10.1093/hmg/3.6.989. PMID 7951250.
• Bement WM, Hasson T, Wirth JA, Cheney RE, Mooseker MS (Jul 1994). "Identification and overlapping expression of multiple unconventional myosin genes in vertebrate cell types". Proceedings of the National Academy of Sciences of the United States of America 91 (14): 6549–53. doi:10.1073/pnas.91.14.6549. PMC 44240. PMID 8022818.
• Wagenaar M, ter Rahe B, van Aarem A, Huygen P, Admiraal R, Bleeker-Wagemakers E, Pinckers A, Kimberling W, Cremers C (Nov 1995). "Clinical findings in obligate carriers of type I Usher syndrome". American Journal of Medical Genetics 59 (3): 375–9. doi:10.1002/ajmg.1320590319. PMID 8599365.
• Weil D, Levy G, Sahly I, Levi-Acobas F, Blanchard S, El-Amraoui A, Crozet F, Philippe H, Abitbol M, Petit C (Apr 1996). "Human myosin VIIA responsible for the Usher 1B syndrome: a predicted membrane-associated motor protein expressed in developing sensory epithelia". Proceedings of the National Academy of Sciences of the United States of America 93 (8): 3232–7. doi:10.1073/pnas.93.8.3232. PMC 39588. PMID 8622919.
• Tamagawa Y, Kitamura K, Ishida T, Ishikawa K, Tanaka H, Tsuji S, Nishizawa M (Jun 1996). "A gene for a dominant form of non-syndromic sensorineural deafness (DFNA11) maps within the region containing the DFNB2 recessive deafness gene". Human Molecular Genetics 5 (6): 849–52. doi:10.1093/hmg/5.6.849. PMID 8776602.
• Chen ZY, Hasson T, Kelley PM, Schwender BJ, Schwartz MF, Ramakrishnan M, Kimberling WJ, Mooseker MS, Corey DP (Sep 1996). "Molecular cloning and domain structure of human myosin-VIIa, the gene product defective in Usher syndrome 1B". Genomics 36 (3): 440–8. doi:10.1006/geno.1996.0489. PMID 8884267.
• Weston MD, Kelley PM, Overbeck LD, Wagenaar M, Orten DJ, Hasson T, Chen ZY, Corey D, Mooseker M, Sumegi J, Cremers C, Moller C, Jacobson SG, Gorin MB, Kimberling WJ (Nov 1996). "Myosin VIIA mutation screening in 189 Usher syndrome type 1 patients". American Journal of Human Genetics 59 (5): 1074–83. PMC 1914835. PMID 8900236.
• Lévy G, Levi-Acobas F, Blanchard S, Gerber S, Larget-Piet D, Chenal V, Liu XZ, Newton V, Steel KP, Brown SD, Munnich A, Kaplan J, Petit C, Weil D (Jan 1997). "Myosin VIIA gene: heterogeneity of the mutations responsible for Usher syndrome type IB". Human Molecular Genetics 6 (1): 111–6. doi:10.1093/hmg/6.1.111. PMID 9002678.
• Kelley PM, Weston MD, Chen ZY, Orten DJ, Hasson T, Overbeck LD, Pinnt J, Talmadge CB, Ing P, Mooseker MS, Corey D, Sumegi J, Kimberling WJ (Feb 1997). "The genomic structure of the gene defective in Usher syndrome type Ib (MYO7A)". Genomics 40 (1): 73–9. doi:10.1006/geno.1996.4545. PMID 9070921.
• Liu XZ, Walsh J, Mburu P, Kendrick-Jones J, Cope MJ, Steel KP, Brown SD (Jun 1997). "Mutations in the myosin VIIA gene cause non-syndromic recessive deafness". Nature Genetics 16 (2): 188–90. doi:10.1038/ng0697-188. PMID 9171832.
• Weil D, Küssel P, Blanchard S, Lévy G, Levi-Acobas F, Drira M, Ayadi H, Petit C (Jun 1997). "The autosomal recessive isolated deafness, DFNB2, and the Usher 1B syndrome are allelic defects of the myosin-VIIA gene". Nature Genetics 16 (2): 191–3. doi:10.1038/ng0697-191. PMID 9171833.
• Liu XZ, Walsh J, Tamagawa Y, Kitamura K, Nishizawa M, Steel KP, Brown SD (Nov 1997). "Autosomal dominant non-syndromic deafness caused by a mutation in the myosin VIIA gene". Nature Genetics 17 (3): 268–9. doi:10.1038/ng1197-268. PMID 9354784.