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Hollfelder N, Erasmus JC, Hammaren R, Vicente M, Jakobsson M, Greeff JM, Schlebusch CM. Patterns of African and Asian admixture in the Afrikaner population of South Africa. BMC Biol 2020; 18:16. [PMID: 32089133 PMCID: PMC7038537 DOI: 10.1186/s12915-020-0746-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 01/31/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Afrikaner population of South Africa is the descendants of European colonists who started to colonize the Cape of Good Hope in the 1600s. In the early days of the colony, mixed unions between European males and non-European females gave rise to admixed children who later became incorporated into either the Afrikaner or the Coloured populations of South Africa. Differences in ancestry, social class, culture, sex ratio and geographic structure led to distinct and characteristic admixture patterns in the Afrikaner and Coloured populations. The Afrikaner population has a predominant European composition, whereas the Coloured population has more diverse ancestries. Genealogical records previously estimated the contribution of non-Europeans into the Afrikaners to be between 5.5 and 7.2%. RESULTS To investigate the genetic ancestry of the Afrikaner population today (11-13 generations after initial colonization), we genotyped approximately five million genome-wide markers in 77 Afrikaner individuals and compared their genotypes to populations across the world to determine parental source populations and admixture proportions. We found that the majority of Afrikaner ancestry (average 95.3%) came from European populations (specifically northwestern European populations), but that almost all Afrikaners had admixture from non-Europeans. The non-European admixture originated mostly from people who were brought to South Africa as slaves and, to a lesser extent, from local Khoe-San groups. Furthermore, despite a potentially small founding population, there is no sign of a recent bottleneck in the Afrikaner compared to other European populations. Admixture amongst diverse groups from Europe and elsewhere during early colonial times might have counterbalanced the effects of a small founding population. CONCLUSIONS While Afrikaners have an ancestry predominantly from northwestern Europe, non-European admixture signals are ubiquitous in the Afrikaner population. Interesting patterns and similarities could be observed between genealogical predictions and our genetic inferences. Afrikaners today have comparable inbreeding levels to current-day European populations.
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Affiliation(s)
- N Hollfelder
- Human Evolution, Department of Organismal Biology, Uppsala University, Norbyvägen 18C, SE-752 36, Uppsala, Sweden
| | - J C Erasmus
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, 0002, South Africa
| | - R Hammaren
- Human Evolution, Department of Organismal Biology, Uppsala University, Norbyvägen 18C, SE-752 36, Uppsala, Sweden
| | - M Vicente
- Human Evolution, Department of Organismal Biology, Uppsala University, Norbyvägen 18C, SE-752 36, Uppsala, Sweden
| | - M Jakobsson
- Human Evolution, Department of Organismal Biology, Uppsala University, Norbyvägen 18C, SE-752 36, Uppsala, Sweden
- Science for Life Laboratory, Uppsala University, Norbyvägen 18C, SE-752 36, Uppsala, Sweden
- Palaeo-Research Institute, University of Johannesburg, P.O. Box 524, Auckland Park, 2006, South Africa
| | - J M Greeff
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, 0002, South Africa.
| | - C M Schlebusch
- Human Evolution, Department of Organismal Biology, Uppsala University, Norbyvägen 18C, SE-752 36, Uppsala, Sweden.
- Science for Life Laboratory, Uppsala University, Norbyvägen 18C, SE-752 36, Uppsala, Sweden.
- Palaeo-Research Institute, University of Johannesburg, P.O. Box 524, Auckland Park, 2006, South Africa.
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Erasmus JC, Bruche S, Pizarro L, Maimari N, Pogglioli T, Tomlinson C, Lees J, Zalivina I, Wheeler A, Alberts A, Russo A, Braga VMM. Defining functional interactions during biogenesis of epithelial junctions. Nat Commun 2016; 7:13542. [PMID: 27922008 PMCID: PMC5150262 DOI: 10.1038/ncomms13542] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 10/13/2016] [Indexed: 12/26/2022] Open
Abstract
In spite of extensive recent progress, a comprehensive understanding of how actin cytoskeleton remodelling supports stable junctions remains to be established. Here we design a platform that integrates actin functions with optimized phenotypic clustering and identify new cytoskeletal proteins, their functional hierarchy and pathways that modulate E-cadherin adhesion. Depletion of EEF1A, an actin bundling protein, increases E-cadherin levels at junctions without a corresponding reinforcement of cell–cell contacts. This unexpected result reflects a more dynamic and mobile junctional actin in EEF1A-depleted cells. A partner for EEF1A in cadherin contact maintenance is the formin DIAPH2, which interacts with EEF1A. In contrast, depletion of either the endocytic regulator TRIP10 or the Rho GTPase activator VAV2 reduces E-cadherin levels at junctions. TRIP10 binds to and requires VAV2 function for its junctional localization. Overall, we present new conceptual insights on junction stabilization, which integrate known and novel pathways with impact for epithelial morphogenesis, homeostasis and diseases. Formation and reinforcement of E-cadherin-mediated adhesion depends on intracellular trafficking and interactions with the actin cytoskeleton, but how these are coordinated is not known. Here the authors conduct a focused phenotypic screen to identify new pathways regulating cell–cell junction homeostasis.
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Affiliation(s)
- J C Erasmus
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - S Bruche
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - L Pizarro
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK.,Computing Department, Imperial College London, London SW7 2AZ, UK
| | - N Maimari
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK.,Bioengineering Department, Faculty of Engineering, Imperial College London, London SW7 2AZ, UK
| | - T Pogglioli
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - C Tomlinson
- Department of Surgery &Cancer, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - J Lees
- Department Structural and Molecular Biology, University College London, London WC1E 6BT, UK
| | - I Zalivina
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - A Wheeler
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - A Alberts
- Van Andel Institute, Grand Rapids, Michigan 49503, USA
| | - A Russo
- Computing Department, Imperial College London, London SW7 2AZ, UK
| | - V M M Braga
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
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