# TIN2L phosphorylation and dyskeratosis congenita pathogenic variants in telomere maintenance

> **NIH NIH F31** · BAYLOR COLLEGE OF MEDICINE · 2020 · $10,405

## Abstract

Project Summary/Abstract
The goal of this project is to understand the function of phosphorylation of the long isoform of TIN2 and its relation
to pathogenic variants causing dyskeratosis congenita (DC). DC is an inherited bone marrow failure syndrome
caused by disruption of telomere maintenance and function. Patients are at risk of life-threatening
myelodysplastic syndrome, immunodeficiency, various cancers, pulmonary fibrosis, and liver disease.
Hematopoietic cell transplantation addresses low blood counts, yet a better understanding will be required to
treat other clinical features and the underlying cause. Monoallelic pathogenic variants in TINF2 (encodes TIN2)
account for approximately 11% of DC-spectrum disorders. Previous studies have focused on the shorter of two
TIN2 isoforms, and the mechanism by which pathogenic variants in TINF2 cause DC remains unclear. TIN2
interacts with TRF2, a shelterin component that directly binds telomeric DNA. Multiple DNA processing factors
are targeted to telomeres through interaction with TRF2. These factors are involved in regulating the length of
the telomeric single stranded 3’ overhang or are involved in telomere homologous recombination. Single
stranded 3’ overhang DNA is required for homologous recombination and excess telomere homologous
recombination can result in massive telomere shortening. Preliminary data leads to the hypothesis that (1)
dynamic phosphorylation of TINL regulates competition of TIN2L and processing factors for interaction
with TRF2 and localization to telomeres by altering TIN2L conformation and (2) TIN2L altered
phosphorylation or the DC-associated R282H disrupts this regulation, resulting in telomere loss via
hyperresection and homologous recombination. To test this hypothesis, this study first proposes to knock-in
a tag to the C-terminus of endogenous TIN2L. Tagged TIN2L will be monitored for cell-cycle specific
phosphorylation and recruitment to TRF2 and telomeres. The correlation of processing factor recruitment to
TRF2 and telomeres throughout the cell-cycle will be assessed. Next, it proposes to knock-in phosphodead and
phosphomimetic mutations and, in a separate cell line, to knock-out TIN2L and integrate inducible TIN2L wild
type or TIN2L R282H, the most common TIN2 DC variant. These cell lines will be used to evaluate the effect of
phosphorylation and R282H on the association of TIN2L and processing factors with TRF2 and telomeres.
Biochemical approaches will be used to assess the competition of TIN2L with processing factors for TRF2
binding, and to determine if phosphodead, phosphomimetic, or R282H mutations alter the conformation of TIN2L.
Finally, cell and molecular biological approaches using the above cell lines will be used to determine whether
these mutations lead to telomere dysfunction. Together, these proposed studies will provide insight into the
role of TIN2L in telomere biology, and will help us achieve the long term goal of improving the
understanding and...

## Key facts

- **NIH application ID:** 9949778
- **Project number:** 5F31HL142185-03
- **Recipient organization:** BAYLOR COLLEGE OF MEDICINE
- **Principal Investigator:** Lois Melissa Dodson
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $10,405
- **Award type:** 5
- **Project period:** 2018-07-01 → 2020-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9949778

## Citation

> US National Institutes of Health, RePORTER application 9949778, TIN2L phosphorylation and dyskeratosis congenita pathogenic variants in telomere maintenance (5F31HL142185-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9949778. Licensed CC0.

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