Details for: CL0000749

Cell ID: CL0000749

Cell Name: ON-bipolar cell

Description: A bipolar neuron found in the retina and having connections with photoreceptors cells and neurons in the inner half of the inner plexiform layer. These cells depolarize in response to light stimulation of their corresponding photoreceptors.

Selected Context(s): Overall

Gene Significance Landscape

Display Options
Score:
Display
Genes

Contexts:

Cell Significance Index (CSI) is uniquely calculated to reveal cell-specific gene markers. More info here

Significant Genes List

Genes with the highest and lowest Percentile Rank Scores (PRS) for ON-bipolar cell within the selected context(s).

Gene ID: A unique numerical identifier for this specific gene.
Symbol: Shortened abbreviation or name that represents this gene.
Ensembl Gene ID: A unique identifier assigned by Ensembl for genomic data mapping.
CSI Score: A combined effect size and statistical significance measure for ON-bipolar cell. Higher scores indicate a stronger, more significant difference in expression.
(Previously described as "Fold Change", but now represents Cliff's Delta × –log10(p).)

Gene ID: A unique numerical identifier for this specific gene.
Symbol: Shortened abbreviation or name that represents this gene.
Ensembl Gene ID: A unique identifier assigned by Ensembl for genomic data mapping.
CSI Score: A combined effect size and statistical significance measure for ON-bipolar cell. Higher scores indicate a stronger, more significant difference in expression.
Average CSI: csi sum / gene count
Cell network configuration

This network visualizes key genes for ON-bipolar cell. It primarily includes:
1. Top genes highly significant for this cell (Num. Top Cell Genes - based on the 'Min. CSI' setting).
2. Any additional specific 'Context Genes' you add below.
The final network is a combined view. Choose an Interaction Source (pathways or protein interactions) and optionally compare CSI scores with a Baseline Cell Type.

Maximum number of selected genes.
Select a context for the baseline cell.
Select a context for the target cell.
Target Cell for CSI:  ON-bipolar cell (CL0000749)

 Legend
Nodes (Genes):
 Query Gene
Node size also reflects Target Cell CSI magnitude.
Node Color (Target Cell CSI in specific network):
 Very High
 High
 Medium
 Low
 Very Low
 N/A or Not Sig.
Edges (Interactions):
 STRING (Protein-Protein)
 ONTOLOGY (Shared Pathway)
 Colors vary by pathway category; default arrow applies.

Loading network (please wait)...

## Summary The [ON-bipolar cell](/details-cell/CL0000749) is a specialized retinal interneuron that depolarizes in response to light, playing a critical role in transmitting visual signals from photoreceptors to ganglion cells. Gene significance analysis reveals that this cell type is defined by an exceptionally high expression specificity of genes involved in mitochondrial oxidative phosphorylation. This signature suggests that the [ON-bipolar cell](/details-cell/CL0000749) operates as a metabolic powerhouse, maintaining a state of high energetic readiness to support the constant demands of synaptic transmission and ion homeostasis required for visual processing. ## Key Characteristics and Function **Overall**, the gene expression profile of the [ON-bipolar cell](/details-cell/CL0000749) is dominated by markers associated with three core biological functions: energy metabolism, neuronal signaling, and protein homeostasis. * **Mitochondrial Bioenergetics:** A striking feature of this cell is the high significance of numerous genes encoding subunits of the mitochondrial respiratory chain and ATP synthase. These include multiple components of Complex III ([UQCRB](/details-gene/7381)), Complex IV ([COX4I1](/details-gene/1327), [COX7A2](/details-gene/1347), [COX7C](/details-gene/1350), [COX6C](/details-gene/1345), [COX6A1](/details-gene/1337), [COX5B](/details-gene/1329)), and Complex V ([ATP5MG](/details-gene/10632), [ATP5MC2](/details-gene/517), [ATP5F1E](/details-gene/514)). This extensive and specific expression profile underscores a profound reliance on aerobic respiration to generate the ATP necessary for its continuous, graded signaling activity. Genes involved in mitochondrial protein import ([TOMM7](/details-gene/54543), [CHCHD2](/details-gene/51142)) and iron metabolism ([FTH1](/details-gene/2495), [FTL](/details-gene/2512)), which is crucial for electron transport chain function, are also highly significant. * **Synaptic Transmission and Calcium Homeostasis:** The cell's identity as a neuron is affirmed by the high specificity of [SYT1](/details-gene/6857) (Synaptotagmin-1), a key calcium sensor for fast neurotransmitter release. This is complemented by the high significance of [CALM2](/details-gene/805) (Calmodulin 2), a primary intracellular calcium sensor, and [SARAF](/details-gene/51669), a regulator of store-operated calcium entry. This suite of markers suggests that [ON-bipolar cells](/details-cell/CL0000749) possess sophisticated machinery to tightly regulate calcium dynamics, which are fundamental to both their response to photoreceptor input and their subsequent glutamate release. * **Protein Synthesis and Maintenance:** A third functional cluster points to active protein and RNA processing. Key markers include [SRP14](/details-gene/6727), a component of the signal recognition particle for protein targeting, and [SRSF5](/details-gene/6430), a pre-mRNA splicing factor. Additionally, genes involved in post-translational modification ([SUMO2](/details-gene/6613)) and protein degradation pathways ([SKP1](/details-gene/6500)) are significant, indicating a high rate of protein turnover required to maintain the integrity of the synaptic machinery. The high significance of [CIRBP](/details-gene/1153) (cold-inducible RNA-binding protein) may indicate a role in mRNA stability and translation under varying physiological conditions. The anti-marker profile further refines the cell's identity. The notably low significance of [B2M](/details-gene/567), an essential component of MHC class I molecules, is consistent with the immune-privileged status of the central nervous system, suggesting these neurons maintain a low profile to the immune system. ## Clinical Significance and Contextual Roles The pronounced metabolic signature of the [ON-bipolar cell](/details-cell/CL0000749) suggests a potential vulnerability to mitochondrial dysfunction. Pathologies affecting the electron transport chain or ATP synthesis could disproportionately impact these high-demand neurons, potentially contributing to the progression of retinopathies characterized by bioenergetic failure. For instance, [CHCHD2](/details-gene/51142), a significant marker involved in mitochondrial protein import, has been linked to neurodegenerative disorders, highlighting a potential shared pathway of vulnerability. Furthermore, the cell's reliance on precise calcium-dependent signaling, underscored by markers like [SYT1](/details-gene/6857), may implicate it in channelopathies or other disorders affecting ion homeostasis. Mutations in [SYT1](/details-gene/6857) are known to cause neurodevelopmental disorders, and its specific role in retinal circuitry warrants further investigation. The strong expression of genes for iron storage, [FTH1](/details-gene/2495) and [FTL](/details-gene/2512), also points to a critical need to manage iron, as dysregulation can lead to oxidative stress via Fenton reactions, a known factor in retinal degeneration. ## Potential Mechanisms and Research Directions 1. **Hypothesis: Metabolic Vulnerability as a Driver of Retinopathy.** The extreme enrichment of genes for oxidative phosphorylation (e.g., [UQCRB](/details-gene/7381), [COX4I1](/details-gene/1327)) suggests that the functional integrity of the ON visual pathway is exceptionally dependent on mitochondrial health. We hypothesize that [ON-bipolar cells](/details-cell/CL0000749) act as a metabolic bottleneck in the retina, making them among the first cell types to fail under conditions of systemic metabolic stress, hypoxia, or in diseases linked to mitochondrial gene defects. * **Surprising Findings:** It is not a single mitochondrial gene, but a vast cohort of genes spanning multiple respiratory complexes, that exhibit high expression specificity. This implies that the entire apparatus for aerobic respiration is a core defining feature of this cell's identity, suggesting a highly specialized and potentially inflexible metabolic program. * **Testable Questions:** Does pharmacological inhibition of mitochondrial Complex IV disproportionately impair the light-evoked synaptic output of [ON-bipolar cells](/details-cell/CL0000749) compared to other retinal neurons, such as [OFF-bipolar cells](/details-cell/CL0000748) or [amacrine cells](/details-cell/CL0000742), in ex-vivo retinal slice recordings? 2. **Hypothesis: Endoplasmic Reticulum Calcium Dynamics Modulate Sustained Visual Signaling.** The specific expression of [SARAF](/details-gene/51669), a regulator of store-operated calcium entry (SOCE), alongside canonical synaptic release machinery ([SYT1](/details-gene/6857)) and calcium sensors ([CALM2](/details-gene/805)), points towards a mechanism for sustaining neurotransmission. We hypothesize that [SARAF](/details-gene/51669)-mediated regulation of ER calcium stores is not merely for housekeeping but actively shapes the temporal properties of sustained glutamate release from bipolar cell terminals during prolonged light stimulation. * **Surprising Findings:** The high significance of [SARAF](/details-gene/51669), a protein known for mediating *slow* inactivation of SOCE ([Link](https://doi.org/10.1016/j.cell.2012.01.055)), is unexpected in a neuron that must respond to rapid changes in light. This suggests SOCE may play a role in adapting the gain or kinetics of the synaptic terminal over longer timescales (seconds to minutes) rather than participating in fast, millisecond-scale signaling. * **Testable Questions:** Using a retinal explant model, does shRNA-mediated knockdown of [SARAF](/details-gene/51669) alter the rate of synaptic depression or the total amount of glutamate released from [ON-bipolar cell](/details-cell/CL0000749) terminals in response to a long-duration (e.g., >30 seconds) light stimulus?