TY - JOUR

T1 - Defective tubulin detyrosination causes structural brain abnormalities with cognitive deficiency in humans and mice

AU - UK IBD Genetics Consortium and COLORS in IBD and Oxford IBD cohort study investigators and WGS500 Consortium

AU - Pagnamenta, Alistair T.

AU - Heemeryck, Pierre

AU - Martin, Hilary C.

AU - Bosc, Christophe

AU - Peris, Leticia

AU - Uszynski, Ivy

AU - Gory-Fauré, Sylvie

AU - Couly, Simon

AU - Deshpande, Charu

AU - Siddiqui, Ata

AU - Elmonairy, Alaa A.

AU - Jayawant, Sandeep

AU - Murthy, Sarada

AU - Walker, Ian

AU - Loong, Lucy

AU - Bauer, Peter

AU - Vossier, Frédérique

AU - Denarier, Eric

AU - Maurice, Tangui

AU - Barbier, Emmanuel L.

AU - Deloulme, Jean Christophe

AU - Taylor, Jenny C.

AU - Blair, Edward M.

AU - Andrieux, Annie

AU - Moutin, Marie Jo

AU - Канапин, Александр Артурович

PY - 2019/10/15

Y1 - 2019/10/15

N2 - Reversible detyrosination of tubulin, the building block of microtubules, is crucial for neuronal physiology. Enzymes responsible for detyrosination were recently identified as complexes of vasohibins (VASHs) one or two with small VASH-binding protein (SVBP). Here we report three consanguineous families, each containing multiple individuals with biallelic inactivation of SVBP caused by truncating variants (p.Q28∗ and p.K13Nfs∗18). Affected individuals show brain abnormalities with microcephaly, intellectual disability and delayed gross motor and speech development. Immunoblot testing in cells with pathogenic SVBP variants demonstrated that the encoded proteins were unstable and non-functional, resulting in a complete loss of VASH detyrosination activity. Svbp knockout mice exhibit drastic accumulation of tyrosinated tubulin and a reduction of detyrosinated tubulin in brain tissue. Similar alterations in tubulin tyrosination levels were observed in cultured neurons and associated with defects in axonal differentiation and architecture. Morphological analysis of the Svbp knockout mouse brains by anatomical magnetic resonance imaging showed a broad impact of SVBP loss, with a 7% brain volume decrease, numerous structural defects and a 30% reduction of some white matter tracts. Svbp knockout mice display behavioural defects, including mild hyperactivity, lower anxiety and impaired social behaviour. They do not, however, show prominent memory defects. Thus, SVBP-deficient mice recapitulate several features observed in human patients. Altogether, our data demonstrate that deleterious variants in SVBP cause this neurodevelopmental pathology, by leading to a major change in brain tubulin tyrosination and alteration of microtubule dynamics and neuron physiology.

AB - Reversible detyrosination of tubulin, the building block of microtubules, is crucial for neuronal physiology. Enzymes responsible for detyrosination were recently identified as complexes of vasohibins (VASHs) one or two with small VASH-binding protein (SVBP). Here we report three consanguineous families, each containing multiple individuals with biallelic inactivation of SVBP caused by truncating variants (p.Q28∗ and p.K13Nfs∗18). Affected individuals show brain abnormalities with microcephaly, intellectual disability and delayed gross motor and speech development. Immunoblot testing in cells with pathogenic SVBP variants demonstrated that the encoded proteins were unstable and non-functional, resulting in a complete loss of VASH detyrosination activity. Svbp knockout mice exhibit drastic accumulation of tyrosinated tubulin and a reduction of detyrosinated tubulin in brain tissue. Similar alterations in tubulin tyrosination levels were observed in cultured neurons and associated with defects in axonal differentiation and architecture. Morphological analysis of the Svbp knockout mouse brains by anatomical magnetic resonance imaging showed a broad impact of SVBP loss, with a 7% brain volume decrease, numerous structural defects and a 30% reduction of some white matter tracts. Svbp knockout mice display behavioural defects, including mild hyperactivity, lower anxiety and impaired social behaviour. They do not, however, show prominent memory defects. Thus, SVBP-deficient mice recapitulate several features observed in human patients. Altogether, our data demonstrate that deleterious variants in SVBP cause this neurodevelopmental pathology, by leading to a major change in brain tubulin tyrosination and alteration of microtubule dynamics and neuron physiology.

UR - http://www.scopus.com/inward/record.url?scp=85076195023&partnerID=8YFLogxK

U2 - 10.1093/hmg/ddz186

DO - 10.1093/hmg/ddz186

M3 - Article

C2 - 31363758

AN - SCOPUS:85076195023

VL - 28

SP - 3391

EP - 3405

JO - Human Molecular Genetics

JF - Human Molecular Genetics

SN - 0964-6906

IS - 20

ER -