Differentiation-coupled intron retention reveals a candidate NKG2D-TR-like isoform at the murine Klrk1 locus
- 1SUNY Upstate Medical University,
Abstract
NKG2D (encoded by KLRK1 in humans and Klrk1 in mice) is an activating receptor expressed by cytotoxic lymphocytes. In humans, NKG2D signaling is regulated post-transcriptionally: activated T cells retain intron 4 of KLRK1 to generate NKG2D-TR, a truncated dominant-negative isoform that limits receptor signaling. Whether mice, the principal preclinical model for NKG2D-directed therapies, possess an analogous regulatory mechanism remains unknown. Across four murine RNA-seq datasets comprising 50 samples and spanning T-cell differentiation, graft-versus-host disease, and acute and chronic LCMV infection, we examined the retained-intron isoform Klrk1-203. The transcript retains the canonical start codon, while its predicted stop codon lies within the terminal exon downstream of the final exon-exon junction, suggesting that it may escape nonsense-mediated decay. If translated, Klrk1-203 is predicted to encode a truncated product that retains the cytoplasmic and transmembrane domains but lacks most of the ligand-binding ectodomain. This predicted architecture resembles human NKG2D-TR, although the murine product contains a short C-terminal sequence encoded by the retained intron. Klrk1-203 was below the detection limit in unchallenged naive and early-effector T cells but was induced in differentiated effector and memory populations, reaching approximately one-fifth of total Klrk1 transcripts in one effector-memory sample. Read-level analyses independently demonstrated increased intron 4 retention with differentiation; however, short-read sequencing cannot fully distinguish Klrk1-203 from the co-retained Klrk1-204 transcript, making isoform-specific abundance dependent on model-based quantification. An independent coding-potential algorithm classified Klrk1-203 as non-coding, providing an important counterpoint to the structural predictions. Together, these findings identify Klrk1-203 as a candidate NMD-resistant, differentiation-associated regulator of murine NKG2D and a potential counterpart of human NKG2D-TR that warrants experimental validation.
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BibTeX
@misc{topkaya2026differentiationcoupled,
title = {{Differentiation-coupled intron retention reveals a candidate NKG2D-TR-like isoform at the murine Klrk1 locus}},
author = {I. H. Topkaya and M. Karimi},
howpublished = {bioRxiv},
year = {2026},
month = aug,
doi = {10.64898/2026.08.21.746301},
url = {https://www.biorxiv.org/content/10.64898/2026.08.21.746301v2},
note = {CC BY},
}
RIS
TY - UNPB
TI - Differentiation-coupled intron retention reveals a candidate NKG2D-TR-like isoform at the murine Klrk1 locus
AU - I. H. Topkaya
AU - M. Karimi
PY - 2026
DA - 2026/08/21
PB - bioRxiv
DO - 10.64898/2026.08.21.746301
UR - https://www.biorxiv.org/content/10.64898/2026.08.21.746301v2
AB - NKG2D (encoded by KLRK1 in humans and Klrk1 in mice) is an activating receptor expressed by cytotoxic lymphocytes. In humans, NKG2D signaling is regulated post-transcriptionally: activated T cells retain intron 4 of KLRK1 to generate NKG2D-TR, a truncated dominant-negative isoform that limits receptor signaling. Whether mice, the principal preclinical model for NKG2D-directed therapies, possess an analogous regulatory mechanism remains unknown. Across four murine RNA-seq datasets comprising 50 samples and spanning T-cell differentiation, graft-versus-host disease, and acute and chronic LCMV infection, we examined the retained-intron isoform Klrk1-203. The transcript retains the canonical start codon, while its predicted stop codon lies within the terminal exon downstream of the final exon-exon junction, suggesting that it may escape nonsense-mediated decay. If translated, Klrk1-203 is predicted to encode a truncated product that retains the cytoplasmic and transmembrane domains but lacks most of the ligand-binding ectodomain. This predicted architecture resembles human NKG2D-TR, although the murine product contains a short C-terminal sequence encoded by the retained intron. Klrk1-203 was below the detection limit in unchallenged naive and early-effector T cells but was induced in differentiated effector and memory populations, reaching approximately one-fifth of total Klrk1 transcripts in one effector-memory sample. Read-level analyses independently demonstrated increased intron 4 retention with differentiation; however, short-read sequencing cannot fully distinguish Klrk1-203 from the co-retained Klrk1-204 transcript, making isoform-specific abundance dependent on model-based quantification. An independent coding-potential algorithm classified Klrk1-203 as non-coding, providing an important counterpoint to the structural predictions. Together, these findings identify Klrk1-203 as a candidate NMD-resistant, differentiation-associated regulator of murine NKG2D and a potential counterpart of human NKG2D-TR that warrants experimental validation.
ER -