MORN5, or MORN repeat containing 5, has the MORN motif found in multiple-copy proteins across animal and plant kingdoms. It is involved in craniofacial development and may interact with the BMP and TGFβ pathways. Its expression in craniofacial structures could be crucial for normal development, and its study in genetic models may help understand its functions [1].

In chicken embryos, MORN5 expression was first seen at stage HH17-18 (E2.5) on either side of the primitive oral cavity. From stage HH20 to HH29 (E3-E6), there was strong expression in the maxillary and mandibular prominences. MORN5 was downregulated after Noggin and/or RA treatment, and BMP pathway genes were downstream of MORN5 following siRNA knockdown. Also, in mice, MORN5 is conserved between mouse and human sperm and is associated with cytoskeletal structures in the sperm flagellum [1,2].

In conclusion, MORN5 plays important roles in craniofacial development and sperm function. Its regulation of BMP signaling in craniofacial development, as seen in the chicken model, and its association with sperm-tail cytoskeletal structures in mice, contribute to understanding these biological processes. These findings may be relevant to human non-syndromic cleft lip with or without cleft palate, based on the association of MORN5 variants with increased risk [1].

References:

1. Cela, Petra, Hampl, Marek, Fu, Katherine K, Richman, Joy M, Buchtova, Marcela. 2016. MORN5 Expression during Craniofacial Development and Its Interaction with the BMP and TGFβ Pathways. In Frontiers in physiology, 7, 378. doi:10.3389/fphys.2016.00378. https://pubmed.ncbi.nlm.nih.gov/27630576/

2. Kwon, Jun Tae, Ham, Sera, Jeon, Suyeon, Oh, Seungmin, Cho, Chunghee. 2017. Expression of uncharacterized male germ cell-specific genes and discovery of novel sperm-tail proteins in mice. In PloS one, 12, e0182038. doi:10.1371/journal.pone.0182038. https://pubmed.ncbi.nlm.nih.gov/28742876/