Syntaxin 4 is essential for hearing in human and zebrafish

  • Hum Mol Genet. 2023 Mar 20;32(7):1184-1192. doi: 10.1093/hmg/ddac257.
Isabelle Schrauwen  1 ,  Amama Ghaffar  2 ,  Thashi Bharadwaj  1 ,  Khadim Shah  3 ,  Sakina Rehman  2 ,  Anushree Acharya  1 ,  Khurram Liaqat  1 ,  Nicole S Lin  1 ,  Jenna L Everard  1 ,  Anwar Khan  4 ,  Zubair M Ahmed  2 ,  Wasim Ahmad  5 ,  Saima Riazuddin  2 ,  Suzanne M Leal  1  6
Affiliations
  • 1. Center for Statistical Genetics, Sergievsky Center, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA.
  • 2. Department of Otorhinolaryngology - Head & Neck Surgery, School of Medicine University of Maryland, Baltimore, MD, USA.
  • 3. Department of Biotechnology, COMSATS University Islamabad, Abbottabad Campus, Khyber Pakhtunkhwa, Pakistan.
  • 4. Department of Biochemistry, Hazara University Mansehra, Khyber Pakhtunkhwa, Pakistan.
  • 5. Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University Islamabad, Islamabad, Pakistan.
  • 6. Taub Institute for Alzheimer's Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA.
PMID: 36355422 DOI: 10.1093/hmg/ddac257
Abstract

Congenital hearing impairment (HI) is a genetically highly heterogeneous disorder in which prompt recognition and intervention are crucial to optimize outcomes. In this study, we used exome Sequencing to investigate a large consanguineous Pakistani family with eight affected individuals showing bilateral severe-to-profound HI. This identified a homozygous splice region variant in STX4 (c.232 + 6T>C), which causes exon skipping and a frameshift, that segregated with HI (two-point logarithm of odds (LOD) score = 5.9). STX4, a member of the syntaxin family, is a component of the SNARE machinery involved in several vesicle transport and recycling pathways. In silico analysis showed that murine orthologue Stx4a is highly and widespread expressed in the developing and adult inner ear. Immunofluorescent imaging revealed localization of STX4A in the cell body, cell membrane and stereocilia of inner and outer hair cells. Furthermore, a morpholino-based knockdown of stx4 in zebrafish showed an abnormal startle response, morphological and developmental defects, and a disrupted mechanotransduction function in neuromast hair cells measured via FM1-43 uptake. Our findings indicate that STX4 dysfunction leads to HI in humans and zebrafish and supports the evolutionary conserved role of STX4 in inner ear development and hair cell functioning.