Evolution of Human Brain Size-Associated NOTCH2NL Genes Proceeds toward Reduced Protein Levels

Gerrald A. Lodewijk, Diana P. Fernandes, Iraklis Vretzakis, Jeanne E. Savage, Frank M.J. Jacobs

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Ever since the availability of genomes from Neanderthals, Denisovans, and ancient humans, the field of evolutionary genomics has been searching for protein-coding variants that may hold clues to how our species evolved over the last ∼600,000 years. In this study, we identify such variants in the human-specific NOTCH2NL gene family, which were recently identified as possible contributors to the evolutionary expansion of the human brain. We find evidence for the existence of unique protein-coding NOTCH2NL variants in Neanderthals and Denisovans which could affect their ability to activate Notch signaling. Furthermore, in the Neanderthal and Denisovan genomes, we find unusual NOTCH2NL configurations, not found in any of the modern human genomes analyzed. Finally, genetic analysis of archaic and modern humans reveals ongoing adaptive evolution of modern human NOTCH2NL genes, identifying three structural variants acting complementary to drive our genome to produce a lower dosage of NOTCH2NL protein. Because copy-number variations of the 1q21.1 locus, encompassing NOTCH2NL genes, are associated with severe neurological disorders, this seemingly contradicting drive toward low levels of NOTCH2NL protein indicates that the optimal dosage of NOTCH2NL may have not yet been settled in the human population.

Original languageEnglish
Pages (from-to)2531-2548
Number of pages18
JournalMolecular biology and evolution
Volume37
Issue number9
DOIs
Publication statusPublished - 1 Sep 2020

Keywords

  • archaic genomes
  • brain size
  • gene conversion
  • human evolutionary genomics
  • human-specific genes, segmental duplications
  • Neanderthal

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