Downregulation of the Long Non-Coding RNA KLRK1-AS1 Disturbs Endothelial Barrier Integrity and Promotes Angiogenic Sprouting

Weiss, Elisa; Kulovic-Sissawo, Azra; van Bergen, Anke S.; Kremer, Veerle; Diniz, Mariana S.; Tocantins, Carolina; Pereira, Susana P.; Boon, Reinier A.; Hiden, Ursula

doi:10.3390/life16020279

Open AccessArticle

Downregulation of the Long Non-Coding RNA KLRK1-AS1 Disturbs Endothelial Barrier Integrity and Promotes Angiogenic Sprouting

by

Elisa Weiss

¹

,

Azra Kulovic-Sissawo

¹

,

Anke S. van Bergen

^2,3

,

Veerle Kremer

^2,3,

Mariana S. Diniz

^1,4,5,6

,

Carolina Tocantins

^1,4,5,6,

Susana P. Pereira

^7,8

,

Reinier A. Boon

^2,3,9,10,† and

Ursula Hiden

^1,*,†

¹

Research Unit Early Life Determinants (ELiD), Medical University of Graz, Auenbruggerplatz 14, 8036 Graz, Austria

²

Department of Physiology, Amsterdam University Medical Centers, De Boelelaan 1108, 1081HZ Amsterdam, The Netherlands

³

Amsterdam Cardiovascular Sciences, Microcirculation, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands

⁴

CNC-UC Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal

⁵

CIBB-Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal

⁶

Institute for Interdisciplinary Research (IIIUC), Doctoral Programme in Experimental Biology and Biomedicine (PDBEB), University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal

⁷

UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology (NOVA FCT), NOVA University of Lisbon, 2829-516 Caparica, Portugal

⁸

Associate Laboratory i4HB, Institute for Health and Bioeconomy, NOVA School of Science and Technology (NOVA FCT), NOVA University of Lisbon, 2829-516 Caparica, Portugal

⁹

Institute for Cardiovascular Regeneration, Centre for Molecular Medicine, Goethe University Frankfurt am Main, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany

¹⁰

German Centre for Cardiovascular Research DZHK, Partner Site Frankfurt Rhein/Main, 60590 Frankfurt am Main, Germany

^*

Author to whom correspondence should be addressed.

^†

These authors contributed equally to this work.

Life 2026, 16(2), 279; https://doi.org/10.3390/life16020279

Submission received: 17 December 2025 / Revised: 28 January 2026 / Accepted: 30 January 2026 / Published: 5 February 2026

(This article belongs to the Section Physiology and Pathology)

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Abstract

Endothelial integrity is essential for cardiovascular health, and circulating endothelial progenitor cells, particularly endothelial colony-forming cells (ECFCs), are key contributors to vascular repair and maintenance. Long non-coding RNAs (lncRNAs) have emerged as novel epigenetic regulators of endothelial physiology and pathology. Building on our previous work identifying the lncRNA KLRK1-AS1 as a positive modulator of ECFC wound healing, we aimed to elucidate its role in endothelial biology. Cord blood-derived ECFCs were subjected to siRNA-mediated silencing of KLRK1-AS1, followed by blinded evaluations of monolayer morphology, barrier stability using ECIS impedance measurements, assessments of proliferation, and spheroid-based angiogenic activity. SiRNA-mediated silencing of KLRK1-AS1 induced detectable alterations in ECFC monolayer morphology (p = 0.047), while proliferation remained unaffected. Notably, KLRK1-AS1 knockdown significantly compromised endothelial barrier integrity, resulting in a 44% reduction in impedance after 48 h (p < 0.001), suggesting weakened intercellular contacts. In contrast, loss of KLRK1-AS1 enhanced angiogenic behaviour, demonstrated by an increased number of sprouts (+62%, p = 0.031). Together, these findings indicate that KLRK1-AS1 supports a quiescent, stable endothelial phenotype, with intact barrier function, while its depletion shifts ECFCs toward a more angiogenic, activated state. Our results identify KLRK1-AS1 as a previously unrecognised regulator of endothelial function.

Keywords: long non-coding RNA (lncRNA); endothelial colony-forming cell (ECFC); proliferation; barrier integrity; angiogenesis; KLRK1-AS1; cardiovascular health

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MDPI and ACS Style

Weiss, E.; Kulovic-Sissawo, A.; van Bergen, A.S.; Kremer, V.; Diniz, M.S.; Tocantins, C.; Pereira, S.P.; Boon, R.A.; Hiden, U. Downregulation of the Long Non-Coding RNA KLRK1-AS1 Disturbs Endothelial Barrier Integrity and Promotes Angiogenic Sprouting. Life 2026, 16, 279. https://doi.org/10.3390/life16020279

AMA Style

Weiss E, Kulovic-Sissawo A, van Bergen AS, Kremer V, Diniz MS, Tocantins C, Pereira SP, Boon RA, Hiden U. Downregulation of the Long Non-Coding RNA KLRK1-AS1 Disturbs Endothelial Barrier Integrity and Promotes Angiogenic Sprouting. Life. 2026; 16(2):279. https://doi.org/10.3390/life16020279

Chicago/Turabian Style

Weiss, Elisa, Azra Kulovic-Sissawo, Anke S. van Bergen, Veerle Kremer, Mariana S. Diniz, Carolina Tocantins, Susana P. Pereira, Reinier A. Boon, and Ursula Hiden. 2026. "Downregulation of the Long Non-Coding RNA KLRK1-AS1 Disturbs Endothelial Barrier Integrity and Promotes Angiogenic Sprouting" Life 16, no. 2: 279. https://doi.org/10.3390/life16020279

APA Style

Weiss, E., Kulovic-Sissawo, A., van Bergen, A. S., Kremer, V., Diniz, M. S., Tocantins, C., Pereira, S. P., Boon, R. A., & Hiden, U. (2026). Downregulation of the Long Non-Coding RNA KLRK1-AS1 Disturbs Endothelial Barrier Integrity and Promotes Angiogenic Sprouting. Life, 16(2), 279. https://doi.org/10.3390/life16020279

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Downregulation of the Long Non-Coding RNA KLRK1-AS1 Disturbs Endothelial Barrier Integrity and Promotes Angiogenic Sprouting

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