Publication Date

1-24-2023

Journal

Proceedings of the National Academy of Sciences of the United States of America

DOI

10.1073/pnas.2209964120

PMID

36669111

PMCID

PMC9942790

PubMedCentral® Posted Date

1-20-2023

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Animals, Female, Humans, Mice, Pregnancy, Central Nervous System, Cilia, Ferrets, Hedgehog Proteins, Mice, Knockout, Signal Transduction, Sonic Hedgehog, polymicrogyria, holoprosencephaly, primary cilia, cortical gyration

Abstract

Sonic hedgehog signaling regulates processes of embryonic development across multiple tissues, yet factors regulating context-specific Shh signaling remain poorly understood. Exome sequencing of families with polymicrogyria (disordered cortical folding) revealed multiple individuals with biallelic deleterious variants in TMEM161B, which encodes a multi-pass transmembrane protein of unknown function. Tmem161b null mice demonstrated holoprosencephaly, craniofacial midline defects, eye defects, and spinal cord patterning changes consistent with impaired Shh signaling, but were without limb defects, suggesting a CNS-specific role of Tmem161b. Tmem161b depletion impaired the response to Smoothened activation in vitro and disrupted cortical histogenesis in vivo in both mouse and ferret models, including leading to abnormal gyration in the ferret model. Tmem161b localizes non-exclusively to the primary cilium, and scanning electron microscopy revealed shortened, dysmorphic, and ballooned ventricular zone cilia in the Tmem161b null mouse, suggesting that the Shh-related phenotypes may reflect ciliary dysfunction. Our data identify TMEM161B as a regulator of cerebral cortical gyration, as involved in primary ciliary structure, as a regulator of Shh signaling, and further implicate Shh signaling in human gyral development.

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