Full-length and internally deleted forms of interleukin-7 are present in horse (Equus caballus) lymph node tissue.

The research discusses the discovery of full-length and shorter forms of horse interleukin-7 (a type of protein that regulates immune system responses) from adult horse lymph nodes and the various responses it stimulates in a specific type of cell culture.

About the Research Objectives

• The research aimed at isolating horse IL-7 cDNA (a form of DNA synthesized from a messenger RNA template) from adult lymph node tissues using reverse transcription polymerase chain reaction (RT-PCR) – a laboratory technique used for creating copies of a specific part of the DNA.
• Along with the full-length (FL) frame of 531 base pairs long that encoded 176 amino acids, shorter sequences of 477, 396, and 264 base pairs were also identified.

Findings from the Nucleotide Sequence Analysis

• The analysis showed homology between the full-length sequence and shorter sequences except for the fact that the latter were missing certain internal sequences. This difference was considered consistent with multiple RNA splicing events – a process that removes non-coding regions from the RNA molecule to create mature RNA.
• Based on these findings, the shorter sequences were named as splice variants (SV) 1 (477 base pairs), 2 (396 base pairs), and 3 (264 base pairs).

Predicted Organization of Horse IL-7

• The sequence organization of horse IL-7 is hypothesized to be similar to that in humans. The researchers observed that SV1 lacks exon 5, SV2 lacks exons 3 and 5, and SV3 lacks exons 3, 4, and 5.
• Exons are distinct parts of a gene that contain the actual coding sequence for protein synthesis.

Protein Production and Stimulation of Cell Proliferation

• It was demonstrated that each of the open-reading frames (segments of the DNA that can potentially be translated into protein) has the potential to be stably expressed. This was tested by visualizing the protein products produced when the FL HIL-7 and each splice variant were cloned into a type of vector (pCI) and transferred into a certain type of cells (HEK 293 cells).
• Further, it was shown that the protein isoforms of horse IL-7 could stimulate proliferation in horse PBMC (peripheral blood mononuclear cell) cultures when added to the culture medium. PBMC cultures are commonly used for a variety of immunology research applications.