Christine Petit graduated in medicine from Pierre et Marie Curie University (Paris VI) and in basic biological sciences, genetics and biochemistry from Orsay University (Paris XI). She received her PhD at the Institut Pasteur. Her research training included microbiological genetics with Gunnar Lindhal and François Jacob, cell genetics, and human genetics with Jean Weissenbach and Pierre Tiollais, and immunology.
In 2002, she was appointed Professor at the Collège de France, and she has held the chair of Genetics and Cellular Physiology since then. She is also currently head of the Genetics and Physiology of Hearing Laboratory, an Inserm unit, at the Institut Pasteur.
Professor Petit is an elected Fellow of the Institute of Medicine of the National Academies, USA, and a member of the French Academy of Sciences.
Awards and distinctions
Named and Honorary Lectures
Research Contribution Christine Petit is a geneticist and a neurobiologist with a particular interest in deafness and hearing, who is internationally renowned for her work on human hereditary sensory disorders. She has pioneered research in this field, revealing the molecular physiology of the cochlea and discovering new physiological properties of this sensory organ.
She initiated the assessment of the molecular mechanisms underlying sound processing in the peripheral auditory system via the genes involved in deafness. Previously, the cochlea had resisted molecular characterization due to the very small number of cells of each type in the cochlea. She was the first to overcome difficulties of linkage analysis for human deafness that had hindered identification of the causative genes. Mainly through the development of an innovative candidate gene strategy, she then discovered more than twenty such genes, 90% of them encoding previously unknown proteins. Through in-depth, multidisciplinary analysis, involving engineered deaf mouse mutants, Christine Petit and her colleagues have unravelled the molecular mechanisms involved in the development and the functioning of the hair bundle (the sensory antenna of the hair cells), the synaptic connections between hair cells and auditory nerve fibres, the formation of the tectorial membrane which transfers the sensory stimulation to the hair bundle, and the maintenance of the ionic composition of the fluid surrounding hair cells. She revealed that the proteins encoded by the five genes responsible for type I Usher syndrome (deafness and blindness) – myosin-VIIa, harmonin, cadherin-23, protocadherin-15 and sans – operate as a protein complex in the hair bundle, as do the three defective proteins in type II Usher syndrome. She uncovered the role of the hair bundle links: embryonic lateral ones formed by the Usher-I protein complex in its cohesion and orientation, basal ones formed by the Usher-II protein complex in its functional polarity and lateral top ones in the suppressive masking implicated in speech intelligibility. She also discovered major components of the mechanotransduction machinery, myosinVIIa, sans and harmonin and elucidated their interactions and functions. Recently, she has identified a previously unsuspected coupling between the mechanotransduction machinery and the control of the hair bundle shape. She also initiated the genetic dissection of the development of the olfactory system through the identification of four genes causative for Kallmann’s syndrome and established that anosmin-1 (KAL1 gene) controls the patterning of the lateral olfactory tract to the olfactory cortex. Christine Petit’s work continuously moved across between basic science and medicine boundaries. By elucidating the pathogenesis of dozens of forms of deafness, including the most frequent form caused by a connexin defect, her discoveries have had a major impact on daily medical practice, regarding both diagnosis and therapeutic decisions and her groundbreaking work has been credited as the most influential on the human genetics of hearing and deafness.
Current research focus the overall aim of Christine Petit’s laboratory is to understand the cellular and molecular mechanisms underlying sound processing in the auditory system and how hearing impairment arise when these mechanisms become defective. The hair bundle, which plays a central role in sound processing, is a main focus of her research. How it is shaped, how basic functions such as mechanotransduction, frequency tuning, waveform distortion and suppressive masking are achieved, how the interaction between these functions is ensured and how its properties are coupled to its cytoarchitecture are some of the key issues that she is addressing. Recently, she has extended her study of sound processing to the central auditory system. Her new research aims include the development of novel approaches to prevent and to treat hearing impairment.