Moore Matthew T, Lin Minshan, Vagnozzi Alicia N, Lopez de Boer Raquel, Brozost Elyse M, Jeannotte Lucie, Lindsay Schwarz, Philippidou Polyxeni
bioRxiv. 2025 Aug 1:2025.08.01.668179. doi: 10.1101/2025.08.01.668179.
Respiratory neurons in the brainstem must diversify and acquire unique properties during development to enable breathing at birth. Dbx1-expressing progenitors give rise to functionally and molecularly distinct excitatory respiratory populations, including rhythm-generating pre-Botzinger complex (preBotC) neurons and phrenic motor neuron (MN)-projecting rostral Ventral Respiratory Group (rVRG) neurons. These neurons are organized rostrocaudally within the ventral respiratory column (VRC) but, despite their critical functions in breathing, the mechanisms that control their organization and diversification are not well understood. Here, we generate a novel genetic tool to label brainstem neurons within the VRC. We find that rVRG neurons selectively express Hox5 genes through postnatal stages. Selective deletion of all Hox5 paralogs from Dbx1-derived neurons leads to respiratory dysfunction, perinatal death, and changes in the pattern and amplitude of phrenic MN firing. We show that Hox5 inactivation leads to a caudal expansion of putative preBotC neurons, likely at the expense of the rVRG. Collectively, our findings indicate that Hox5 proteins are required for the delineation and functional specialization of excitatory brainstem neurons essential for breathing.
脑干中的呼吸神经元在发育过程中必须多样化并获得独特的特性，以便在出生时能够呼吸。表达Dbx1的祖细胞产生功能和分子上不同的兴奋性呼吸群体，包括产生节律的前包钦格复合体（preBotC）神经元和投射到膈运动神经元（MN）的 Rostral Ventral Respiratory Group（rVRG）神经元。这些神经元在腹侧呼吸柱（VRC）内按头尾方向排列，但是，尽管它们在呼吸中具有关键功能，控制它们的组织和多样化的机制仍未得到很好的理解。在这里，我们生成了一种新型的遗传工具来标记VRC内的脑干神经元。我们发现rVRG神经元在出生后阶段选择性地表达Hox5基因。从Dbx1衍生的神经元中选择性删除所有Hox5旁系同源物会导致呼吸功能障碍、围产期死亡以及膈运动神经元放电模式和幅度的变化。我们表明Hox5失活导致假定的preBotC神经元向尾侧扩展，可能是以rVRG为代价。总的来说，我们的研究结果表明Hox5蛋白是呼吸必需的兴奋性脑干神经元的划分和功能特化所必需的。
