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Analyzing the functions of Translationally controlled tumor protein2 during growth, development and autophagy of

Chanchal Choudhary¹, Bhavya Jain¹, Shweta Saran¹

¹School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.

Experimental Cell Research

|January 3, 2025

Abstract:

Translationally controlled tumor protein (TCTP) is a well conserved and ubiquitously expressed multifunctional protein found in many organisms and is involved in many pathophysiological processes like cell proliferation, differentiation, development and cell death. The role of TCTP in anti-apoptosis and cancer metastasis makes it a promising candidate for cancer therapy. Dictyostelium discoideum, a protist, has two isoforms (TCTP1 and TCTP2, now referred to as TPT1 and TPT2) of which we have earlier elucidated TPT1. Here, we analyzed the role of TPT2 in this organism. tpt2 transcript was present throughout growth and development and is localized in the prestalk/stalk regions of multicellular structures developed. tpt2 gene was disrupted with a BSR cassette using a double homologous recombination method. Disruption of tpt2 gene (tpt2‾) exhibit reduced cell proliferation and nutrient-uptake. Additionally, development in tpt2‾ was delayed by 2 h, formed small-sized aggregates that developed into stalky fruiting bodies with reduced spore viability. In contrast, overexpressed tpt2 (tpt2^OE) showed increased cell proliferation and development, formed large-size aggregates that developed into spory fruiting bodies with increased spore viability. TPT2 regulates prestalk/prespore ratio and cell-type differentiation as abrogation of tpt2 gene resulted in altered localization of cell-type markers and an inclination towards the prestalk/stalk pathway while tpt2^OE showed a prespore/spore biasness when mixed with wild-type cells. Deletion of either tpt1 or tpt2 gene showed increased autophagic flux indicating their involvement in negative regulation of autophagy. This study provides insights into the intricate involvement of TCTP in cellular dynamics and development of D. discoideum.

Insights

Translationally controlled tumor protein 2 (TPT2) in Dictyostelium discoideum regulates cell proliferation, development, and differentiation. Its absence or overexpression impacts multicellular structure formation and autophagy, highlighting TPT2

Area of Science:

Cell Biology
Developmental Biology
Molecular Biology

Background:

Translationally controlled tumor protein (TCTP) is a multifunctional protein implicated in cancer and development.
Dictyostelium discoideum possesses two TCTP isoforms, TPT1 and TPT2, with TPT1's function previously characterized.
The role of TPT2 in D. discoideum cellular dynamics and development remained largely unexplored.

Purpose of the Study:

To investigate the specific functions of TPT2 in the model organism Dictyostelium discoideum.
To elucidate TPT2's role in cell proliferation, nutrient uptake, and multicellular development.
To determine TPT2's influence on cell-type differentiation and autophagy.

Main Methods:

Gene disruption of tpt2 using double homologous recombination with a BSR cassette.
Analysis of tpt2 transcript localization during growth and development.
Phenotypic characterization of tpt2 knockout (tpt2‾) and TPT2 overexpressed (tpt2^OE) strains, including cell proliferation, aggregate formation, and fruiting body development.
Assessment of cell-type differentiation by examining marker localization and cell mixing experiments.
Evaluation of autophagic flux in tpt1 and tpt2 deletion mutants.

Main Results:

TPT2 transcript is localized in the prestalk/stalk regions of developing multicellular structures.
Disruption of tpt2 resulted in reduced cell proliferation, delayed development, smaller aggregates, and decreased spore viability.
TPT2 overexpression led to increased cell proliferation, accelerated development, larger aggregates, and enhanced spore viability.
TPT2 regulates the prestalk/prespore ratio, with tpt2‾ favoring prestalk/stalk differentiation and tpt2^OE showing a prespore/spore bias.
Deletion of tpt1 or tpt2 increased autophagic flux, indicating negative regulation of autophagy.

Conclusions:

TPT2 plays a crucial role in regulating cell proliferation, nutrient uptake, and developmental timing in D. discoideum.
TPT2 is essential for proper cell-type differentiation, influencing the balance between prestalk and prespore cell fates.
Both TPT1 and TPT2 are negative regulators of autophagy, contributing to cellular homeostasis.
This study provides significant insights into the multifaceted roles of TCTP family proteins in cellular processes and organismal development.

Read full analysis

Keywords:

Autophagy Cell differentiation Cell proliferation Cell-type patterning Dictyostelium TCTP

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