Related Experiment Video

Updated: Aug 7, 2026

Quantitative PCR-based Assay to Measure Sonic Hedgehog Signaling in Cellular Model of Ciliogenesis
07:26

Quantitative PCR-based Assay to Measure Sonic Hedgehog Signaling in Cellular Model of Ciliogenesis

Published on: January 31, 2025

Somatostatin modulates PI3K-Akt, eNOS and NHE activity in the ciliary epithelium

Sikha Ghosh1, Lars Choritz, John Geibel

  • 1Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT 06510, USA.

Molecular and Cellular Endocrinology
|June 13, 2006
PubMed

Insights

Somatostatin (SST) influences ocular ciliary epithelium (CE) function by regulating Na+/H+-exchanger activity and activating Akt/eNOS signaling pathways. This peptide plays a role in ocular neuroendocrine signaling.

Area of Science:

  • Ocular physiology
  • Neuroendocrinology
  • Cell signaling

Background:

  • Somatostatin (SST) is a peptide hormone produced by neuroendocrine cells.
  • Its role in ocular tissues, specifically the ciliary epithelium (CE), is not fully understood.

Purpose of the Study:

  • To investigate the expression of pro-SST and its receptors in the ocular CE.
  • To determine the effects of exogenous SST on CE function and intracellular signaling pathways.

Main Methods:

  • RT-PCR for pro-SST and SST receptor mRNA expression.
  • Radioimmunoassay for SST detection in ciliary processes and aqueous humor.
  • Immunohistochemistry for pro-SST, PC1, and PC2.
  • Functional assays for Na+/H+-exchanger (NHE) activity, Akt/eNOS phosphorylation, and cyclic GMP levels.
  • Inhibition studies using LY294002 (PI3K inhibitor).

Main Results:

  • Pro-SST and SST receptors (SSTR1, SSTR2A) mRNA were detected in the CE.
  • SST and proprotein convertases (PC1, PC2) showed distinct immunolabeling in the CE, suggesting local pro-SST processing.
  • Exogenous SST dose-dependently attenuated NHE activity.
  • SST increased phosphorylation of Akt-Ser473 and eNOS-Ser617.
  • SST did not affect intracellular cyclic GMP production.
  • PI3K inhibition blocked SST-induced Akt phosphorylation and partially inhibited eNOS phosphorylation but did not reverse NHE attenuation.

Conclusions:

  • The ocular ciliary epithelium expresses and processes somatostatin.
  • SST modulates ciliary epithelium function through distinct intracellular signaling pathways, including NHE activity and PI3K/Akt/eNOS.
  • These findings suggest a novel role for somatostatin in ocular physiology.

More Related Videos

Mechanism of Kemeng Fang's Inhibition of Podocyte Apoptosis in Rats with Membranous Nephropathy through the PI3K/AKT Signaling Pathway07:15

Mechanism of Kemeng Fang's Inhibition of Podocyte Apoptosis in Rats with Membranous Nephropathy through the PI3K/AKT Signaling Pathway

Published on: August 23, 2024

Related Concept Videos

PI3K/mTOR/AKT Signaling Pathway01:22

PI3K/mTOR/AKT Signaling Pathway

The mammalian target of rapamycin  (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1  (mTORC1) and mTOR complex 2  (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast,  mTORC2 consists of a rapamycin-insensitive companion...
The JAK-STAT Signaling Pathway01:20

The JAK-STAT Signaling Pathway

Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as  SH2...
mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
Cell Specific Gene Expression01:58

Cell Specific Gene Expression

Multicellular organisms contain a variety of structurally and functionally distinct cell types, but the DNA in all the cells originated from the same parent cells. The differences in the cells can be attributed to the differential gene expression. Liver cells, whose functions include detoxification of blood, production of bile to metabolize fats, and synthesis of proteins essential for metabolism, must express a specific set of genes to perform their functions. Gene expression also varies with...
Role Of Notch Signalling In Intestinal Stem Cell Renewal01:12

Role Of Notch Signalling In Intestinal Stem Cell Renewal

Notch signaling was first discovered in Drosophila melanogaster, where it is involved in cell lineage differentiation. Notch signaling regulates the maintenance and differentiation of intestinal stem cells or ISCs by controlling the expression of atonal homolog 1 or Atoh1. Atoh1 directs cells to differentiate into secretory cells.
Direct cell-to-cell contact is needed for the activation of Notch signaling. The signal is initiated when a notch ligand binds to a receptor on an adjacent cell, also...
Regulation of Angiogenesis and Blood Supply01:24

Regulation of Angiogenesis and Blood Supply

Rapidly dividing tumors, embryos, and wounded tissues require more oxygen than usual, lowering the oxygen concentration in the blood. At low oxygen or hypoxic conditions, an oxygen-sensitive transcription factor called the hypoxia-inducible factor 1 or HIF1 is activated. HIF1 is a dimeric protein of alpha (ɑ) and beta (β) subunits.  Under optimal oxygen conditions, HIF1β is present in the nucleus while HIF1ɑ remains in the cytosol. HIF1ɑ is hydroxylated by prolyl hydroxylase and factor...