Honors & Awards
Postdoctoral Fellow, NIH, K99/R00 Pathway to Independence Award (2017-2022)
Postdoctoral Fellow, The Jane Coffin Childs Fund for Medical Research (2014-2017)
Predoctoral Fellow, The American Heart Association (2011-2013)
Doctor of Philosophy, Baylor College Of Medicine (2013)
Master of Science, National Taiwan University (2006)
Bachelor of Science, National Cheng Kung University (2004)
Liqun Luo, Postdoctoral Faculty Sponsor
Early adolescent Rai1 reactivation reverses transcriptional and social interaction deficits in a mouse model of Smith-Magenis syndrome.
Proceedings of the National Academy of Sciences of the United States of America
Haploinsufficiency of Retinoic Acid Induced 1 (RAI1) causes Smith-Magenis syndrome (SMS), a syndromic autism spectrum disorder associated with craniofacial abnormalities, intellectual disability, and behavioral problems. There is currently no cure for SMS. Here, we generated a genetic mouse model to determine the reversibility of SMS-like neurobehavioral phenotypes in Rai1 heterozygous mice. We show that normalizing the Rai1 level 3-4 wk after birth corrected the expression of genes related to neural developmental pathways and fully reversed a social interaction deficit caused by Rai1 haploinsufficiency. In contrast, Rai1 reactivation 7-8 wk after birth was not beneficial. We also demonstrated that the correct Rai1 dose is required in both excitatory and inhibitory neurons for proper social interactions. Finally, we found that Rai1 heterozygous mice exhibited a reduction of dendritic spines in the medial prefrontal cortex (mPFC) and that optogenetic activation of mPFC neurons in adults improved the social interaction deficit of Rai1 heterozygous mice. Together, these results suggest the existence of a postnatal temporal window during which restoring Rai1 can improve the transcriptional and social behavioral deficits in a mouse model of SMS. It is possible that circuit-level interventions would be beneficial beyond this critical window.
View details for DOI 10.1073/pnas.1806796115
View details for PubMedID 30275311
Respiratory Network Stability and Modulatory Response to Substance P Require Nalcn.
Respiration is a rhythmic activity as well as one that requires responsiveness to internal and external circumstances; both the rhythm and neuromodulatory responses of breathing are controlled by brainstem neurons in the preBötzinger complex (preBötC) and the retrotrapezoid nucleus (RTN), but the specific ion channels essential to these activities remain to be identified. Because deficiency of sodium leak channel, non-selective (Nalcn) causes lethal apnea in humans and mice, we investigated Nalcn function in these neuronal groups. We found that one-third of mice lacking Nalcn in excitatory preBötC neurons died soon after birth; surviving mice developed apneas in adulthood. Interestingly, in both preBötC and RTN neurons, the Nalcn current influences the resting membrane potential, contributes to maintenance of stable network activity, and mediates modulatory responses to the neuropeptide substance P. These findings reveal Nalcn's specific role in both rhythmic stability and responsiveness to neuropeptides within the respiratory network.
View details for DOI 10.1016/j.neuron.2017.03.024
View details for PubMedID 28392070
Molecular and Neural Functions of Rai1, the Causal Gene for Smith-Magenis Syndrome.
2016; 92 (2): 392-406
Haploinsufficiency of Retinoic Acid Induced 1 (RAI1) causes Smith-Magenis syndrome (SMS), which is associated with diverse neurodevelopmental and behavioral symptoms as well as obesity. RAI1 encodes a nuclear protein but little is known about its molecular function or the cell types responsible for SMS symptoms. Using genetically engineered mice, we found that Rai1 preferentially occupies DNA regions near active promoters and promotes the expression of a group of genes involved in circuit assembly and neuronal communication. Behavioral analyses demonstrated that pan-neural loss of Rai1 causes deficits in motor function, learning, and food intake. These SMS-like phenotypes are produced by loss of Rai1 function in distinct neuronal types: Rai1 loss in inhibitory neurons or subcortical glutamatergic neurons causes learning deficits, while Rai1 loss in Sim1(+) or SF1(+) cells causes obesity. By integrating molecular and organismal analyses, our study suggests potential therapeutic avenues for a complex neurodevelopmental disorder.
View details for DOI 10.1016/j.neuron.2016.09.019
View details for PubMedID 27693255
Atoh1-dependent rhombic lip neurons are required for temporal delay between independent respiratory oscillators in embryonic mice.
All motor behaviors require precise temporal coordination of different muscle groups. Breathing, for example, involves the sequential activation of numerous muscles hypothesized to be driven by a primary respiratory oscillator, the preBötzinger Complex, and at least one other as-yet unidentified rhythmogenic population. We tested the roles of Atoh1-, Phox2b-, and Dbx1-derived neurons (three groups that have known roles in respiration) in the generation and coordination of respiratory output. We found that Dbx1-derived neurons are necessary for all respiratory behaviors, whereas independent but coupled respiratory rhythms persist from at least three different motor pools after eliminating or silencing Phox2b- or Atoh1-expressing hindbrain neurons. Without Atoh1 neurons, however, the motor pools become temporally disorganized and coupling between independent respiratory oscillators decreases. We propose Atoh1 neurons tune the sequential activation of independent oscillators essential for the fine control of different muscles during breathing.
View details for DOI 10.7554/eLife.02265
View details for PubMedID 24842997
Atoh1 Governs the Migration of Postmitotic Neurons that Shape Respiratory Effectiveness at Birth and Chemoresponsiveness in Adulthood
2012; 75 (5): 799-809
Hindbrain neuronal networks serving respiratory, proprioceptive, and arousal functions share a developmental requirement for the bHLH transcription factor Atoh1. Loss of Atoh1 in mice results in respiratory failure and neonatal lethality; however, the neuronal identity and mechanism by which Atoh1-dependent cells sustain newborn breathing remains unknown. We uncovered that selective loss of Atoh1 from the postmitotic retrotrapezoid nucleus (RTN) neurons results in severely impaired inspiratory rhythm and pronounced neonatal death. Mice that escape neonatal death develop abnormal chemoresponsiveness as adults. Interestingly, the expression of Atoh1 in the RTN neurons is not required for their specification or maintenance, but is important for their proper localization and to establish essential connections with the preBötzinger Complex (preBötC). These results provide insights into the genetic regulation of neonatal breathing and shed light on the labile sites that might contribute to sudden death in newborn infants and altered chemoresponsiveness in adults.
View details for DOI 10.1016/j.neuron.2012.06.027
View details for Web of Science ID 000308684300008
View details for PubMedID 22958821