T-Cell Leukemia Homeobox Protein 3 (TLX3)

RNX (HOX11L2, TLX3) belongs to a family of orphan homeobox genes that encode DNA-binding nuclear transcription factors. Members of the HOX11 gene family are characterized by a threonine-47 replacing cytosine in the highly conserved homeodomain. Rnx-deficient mice developed to term, but all died within 24 hours after birth from a central respiratory failure. The electromyographic activity of intercostal muscles coupled with the C4 ventral root activity assessed in a medulla-spinal cord preparation revealed a high respiratory rate with short inspiratory duration and frequent apnea. Furthermore, a coordinate pattern existed between the abnormal activity of inspiratory neurons in the ventrolateral medulla and C4 motorneuron output, indicating a central respiratory defect in Rnx.